Computational modeling and analysis for left ventricle motion using CT/Echo image fusion

NASA Astrophysics Data System (ADS)

Kim, Ji-Yeon; Kang, Nahyup; Lee, Hyoung-Euk; Kim, James D. K.

2014-03-01

In order to diagnose heart disease such as myocardial infarction, 2D strain through the speckle tracking echocardiography (STE) or the tagged MRI is often used. However out-of-plane strain measurement using STE or tagged MRI is inaccurate. Therefore, strain for whole organ which are analyzed by simulation of 3D cardiac model can be applied in clinical diagnosis. To simulate cardiac contraction in a cycle, cardiac physical properties should be reflected in cardiac model. The myocardial wall in left ventricle is represented as a transversely orthotropic hyperelastic material, with the fiber orientation varying sequentially from the epicardial surface, through about 0° at the midwall, to the endocardial surface. A time-varying elastance model is simulated to contract myocardial fiber, and physiological intraventricular systolic pressure curves are employed for the cardiac dynamics simulation in a cycle. And an exact description of the cardiac motion should be acquired in order that essential boundary conditions for cardiac simulation are obtained effectively. Real time cardiac motion can be acquired by using echocardiography and exact cardiac geometrical 3D model can be reconstructed using 3D CT data. In this research, image fusion technology from CT and echocardiography is employed in order to consider patient-specific left ventricle movement. Finally, longitudinal strain from speckle tracking echocardiography which is known to fit actual left ventricle deformation relatively well is used to verify these results.

Evaluation of respiratory and cardiac motion correction schemes in dual gated PET/CT cardiac imaging.

PubMed

Lamare, F; Le Maitre, A; Dawood, M; Schäfers, K P; Fernandez, P; Rimoldi, O E; Visvikis, D

2014-07-01

Cardiac imaging suffers from both respiratory and cardiac motion. One of the proposed solutions involves double gated acquisitions. Although such an approach may lead to both respiratory and cardiac motion compensation there are issues associated with (a) the combination of data from cardiac and respiratory motion bins, and (b) poor statistical quality images as a result of using only part of the acquired data. The main objective of this work was to evaluate different schemes of combining binned data in order to identify the best strategy to reconstruct motion free cardiac images from dual gated positron emission tomography (PET) acquisitions. A digital phantom study as well as seven human studies were used in this evaluation. PET data were acquired in list mode (LM). A real-time position management system and an electrocardiogram device were used to provide the respiratory and cardiac motion triggers registered within the LM file. Acquired data were subsequently binned considering four and six cardiac gates, or the diastole only in combination with eight respiratory amplitude gates. PET images were corrected for attenuation, but no randoms nor scatter corrections were included. Reconstructed images from each of the bins considered above were subsequently used in combination with an affine or an elastic registration algorithm to derive transformation parameters allowing the combination of all acquired data in a particular position in the cardiac and respiratory cycles. Images were assessed in terms of signal-to-noise ratio (SNR), contrast, image profile, coefficient-of-variation (COV), and relative difference of the recovered activity concentration. Regardless of the considered motion compensation strategy, the nonrigid motion model performed better than the affine model, leading to higher SNR and contrast combined with a lower COV. Nevertheless, when compensating for respiration only, no statistically significant differences were observed in the performance of the two motion models considered. Superior image SNR and contrast were seen using the affine respiratory motion model in combination with the diastole cardiac bin in comparison to the use of the whole cardiac cycle. In contrast, when simultaneously correcting for cardiac beating and respiration, the elastic respiratory motion model outperformed the affine model. In this context, four cardiac bins associated with eight respiratory amplitude bins seemed to be adequate. Considering the compensation of respiratory motion effects only, both affine and elastic based approaches led to an accurate resizing and positioning of the myocardium. The use of the diastolic phase combined with an affine model based respiratory motion correction may therefore be a simple approach leading to significant quality improvements in cardiac PET imaging. However, the best performance was obtained with the combined correction for both cardiac and respiratory movements considering all the dual-gated bins independently through the use of an elastic model based motion compensation.

Accelerated acquisition of tagged MRI for cardiac motion correction in simultaneous PET-MR: Phantom and patient studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Chuan, E-mail: chuan.huang@stonybrookmedicine.edu; Department of Radiology, Harvard Medical School, Boston, Massachusetts 02115; Departments of Radiology, Psychiatry, Stony Brook Medicine, Stony Brook, New York 11794

2015-02-15

Purpose: Degradation of image quality caused by cardiac and respiratory motions hampers the diagnostic quality of cardiac PET. It has been shown that improved diagnostic accuracy of myocardial defect can be achieved by tagged MR (tMR) based PET motion correction using simultaneous PET-MR. However, one major hurdle for the adoption of tMR-based PET motion correction in the PET-MR routine is the long acquisition time needed for the collection of fully sampled tMR data. In this work, the authors propose an accelerated tMR acquisition strategy using parallel imaging and/or compressed sensing and assess the impact on the tMR-based motion corrected PETmore » using phantom and patient data. Methods: Fully sampled tMR data were acquired simultaneously with PET list-mode data on two simultaneous PET-MR scanners for a cardiac phantom and a patient. Parallel imaging and compressed sensing were retrospectively performed by GRAPPA and kt-FOCUSS algorithms with various acceleration factors. Motion fields were estimated using nonrigid B-spline image registration from both the accelerated and fully sampled tMR images. The motion fields were incorporated into a motion corrected ordered subset expectation maximization reconstruction algorithm with motion-dependent attenuation correction. Results: Although tMR acceleration introduced image artifacts into the tMR images for both phantom and patient data, motion corrected PET images yielded similar image quality as those obtained using the fully sampled tMR images for low to moderate acceleration factors (<4). Quantitative analysis of myocardial defect contrast over ten independent noise realizations showed similar results. It was further observed that although the image quality of the motion corrected PET images deteriorates for high acceleration factors, the images were still superior to the images reconstructed without motion correction. Conclusions: Accelerated tMR images obtained with more than 4 times acceleration can still provide relatively accurate motion fields and yield tMR-based motion corrected PET images with similar image quality as those reconstructed using fully sampled tMR data. The reduction of tMR acquisition time makes it more compatible with routine clinical cardiac PET-MR studies.« less

Prognostic value of high-dose dobutamine stress magnetic resonance imaging in 1,493 consecutive patients: assessment of myocardial wall motion and perfusion.

PubMed

Korosoglou, Grigorios; Elhmidi, Yacine; Steen, Henning; Schellberg, Dieter; Riedle, Nina; Ahrens, Johannes; Lehrke, Stephanie; Merten, Constanze; Lossnitzer, Dirk; Radeleff, Jannis; Zugck, Christian; Giannitsis, Evangelos; Katus, Hugo A

2010-10-05

This study sought to determine the prognostic value of wall motion and perfusion assessment during high-dose dobutamine stress (DS) cardiac magnetic resonance imaging (MRI) in a large patient cohort. DS-MRI offers the possibility to integrate myocardial perfusion and wall motion analysis in a single examination for the detection of coronary artery disease (CAD). A total of 1,493 consecutive patients with suspected or known CAD underwent DS-MRI, using a standard protocol in a 1.5-T magnetic resonance scanner. Wall motion and perfusion were assessed at baseline and during stress, and outcome data including cardiac death, nonfatal myocardial infarction ("hard events"), and "late" revascularization performed >90 days after the MR scans were collected during a 2 ± 1 year follow-up period. Fifty-three hard events, including 14 cardiac deaths and 39 nonfatal infarctions, occurred during the follow-up period, whereas 85 patients underwent "late" revascularization. Using multivariable regression analysis, an abnormal result for wall motion or perfusion during stress yielded the strongest independent prognostic value for both hard events and late revascularization, clearly surpassing that of clinical and baseline magnetic resonance parameters (for wall motion: adjusted hazard ratio [HR] of 5.9 [95% confidence interval (CI): 2.5 to 13.6] for hard events and of 3.1 [95% CI: 1.7 to 5.6] for late revascularization, and for perfusion: adjusted HR of 5.4 [95% CI: 2.3 to 12.9] for hard events and of 6.2 [95% CI: 3.3 to 11.3] for late revascularization, p < 0.001 for all). DS-MRI can accurately identify patients who are at increased risk for cardiac death and myocardial infarction, separating them from those with normal findings, who have very low risk for future cardiac events. (Prognostic Value of High Dose Dobutamine Stress Magnetic Resonance Imaging; NCT00837005). Copyright © 2010 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Evaluation of respiratory and cardiac motion correction schemes in dual gated PET/CT cardiac imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lamare, F., E-mail: frederic.lamare@chu-bordeaux.fr; Fernandez, P.; CNRS, INCIA, UMR 5287, F-33400 Talence

Purpose: Cardiac imaging suffers from both respiratory and cardiac motion. One of the proposed solutions involves double gated acquisitions. Although such an approach may lead to both respiratory and cardiac motion compensation there are issues associated with (a) the combination of data from cardiac and respiratory motion bins, and (b) poor statistical quality images as a result of using only part of the acquired data. The main objective of this work was to evaluate different schemes of combining binned data in order to identify the best strategy to reconstruct motion free cardiac images from dual gated positron emission tomography (PET)more » acquisitions. Methods: A digital phantom study as well as seven human studies were used in this evaluation. PET data were acquired in list mode (LM). A real-time position management system and an electrocardiogram device were used to provide the respiratory and cardiac motion triggers registered within the LM file. Acquired data were subsequently binned considering four and six cardiac gates, or the diastole only in combination with eight respiratory amplitude gates. PET images were corrected for attenuation, but no randoms nor scatter corrections were included. Reconstructed images from each of the bins considered above were subsequently used in combination with an affine or an elastic registration algorithm to derive transformation parameters allowing the combination of all acquired data in a particular position in the cardiac and respiratory cycles. Images were assessed in terms of signal-to-noise ratio (SNR), contrast, image profile, coefficient-of-variation (COV), and relative difference of the recovered activity concentration. Results: Regardless of the considered motion compensation strategy, the nonrigid motion model performed better than the affine model, leading to higher SNR and contrast combined with a lower COV. Nevertheless, when compensating for respiration only, no statistically significant differences were observed in the performance of the two motion models considered. Superior image SNR and contrast were seen using the affine respiratory motion model in combination with the diastole cardiac bin in comparison to the use of the whole cardiac cycle. In contrast, when simultaneously correcting for cardiac beating and respiration, the elastic respiratory motion model outperformed the affine model. In this context, four cardiac bins associated with eight respiratory amplitude bins seemed to be adequate. Conclusions: Considering the compensation of respiratory motion effects only, both affine and elastic based approaches led to an accurate resizing and positioning of the myocardium. The use of the diastolic phase combined with an affine model based respiratory motion correction may therefore be a simple approach leading to significant quality improvements in cardiac PET imaging. However, the best performance was obtained with the combined correction for both cardiac and respiratory movements considering all the dual-gated bins independently through the use of an elastic model based motion compensation.« less

Improved cardiac motion detection from ultrasound images using TDIOF: a combined B-mode/ tissue Doppler approach

NASA Astrophysics Data System (ADS)

Tavakoli, Vahid; Stoddard, Marcus F.; Amini, Amir A.

2013-03-01

Quantitative motion analysis of echocardiographic images helps clinicians with the diagnosis and therapy of patients suffering from cardiac disease. Quantitative analysis is usually based on TDI (Tissue Doppler Imaging) or speckle tracking. These methods are based on two independent techniques - the Doppler Effect and image registration, respectively. In order to increase the accuracy of the speckle tracking technique and cope with the angle dependency of TDI, herein, a combined approach dubbed TDIOF (Tissue Doppler Imaging Optical Flow) is proposed. TDIOF is formulated based on the combination of B-mode and Doppler energy terms in an optical flow framework and minimized using algebraic equations. In this paper, we report on validations with simulated, physical cardiac phantom, and in-vivo patient data. It is shown that the additional Doppler term is able to increase the accuracy of speckle tracking, the basis for several commercially available echocardiography analysis techniques.

Physiome-model-based state-space framework for cardiac deformation recovery.

PubMed

Wong, Ken C L; Zhang, Heye; Liu, Huafeng; Shi, Pengcheng

2007-11-01

To more reliably recover cardiac information from noise-corrupted, patient-specific measurements, it is essential to employ meaningful constraining models and adopt appropriate optimization criteria to couple the models with the measurements. Although biomechanical models have been extensively used for myocardial motion recovery with encouraging results, the passive nature of such constraints limits their ability to fully count for the deformation caused by active forces of the myocytes. To overcome such limitations, we propose to adopt a cardiac physiome model as the prior constraint for cardiac motion analysis. The cardiac physiome model comprises an electric wave propagation model, an electromechanical coupling model, and a biomechanical model, which are connected through a cardiac system dynamics for a more complete description of the macroscopic cardiac physiology. Embedded within a multiframe state-space framework, the uncertainties of the model and the patient's measurements are systematically dealt with to arrive at optimal cardiac kinematic estimates and possibly beyond. Experiments have been conducted to compare our proposed cardiac-physiome-model-based framework with the solely biomechanical model-based framework. The results show that our proposed framework recovers more accurate cardiac deformation from synthetic data and obtains more sensible estimates from real magnetic resonance image sequences. With the active components introduced by the cardiac physiome model, cardiac deformations recovered from patient's medical images are more physiologically plausible.

Tracking brain motion during the cardiac cycle using spiral cine-DENSE MRI

PubMed Central

Zhong, Xiaodong; Meyer, Craig H.; Schlesinger, David J.; Sheehan, Jason P.; Epstein, Frederick H.; Larner, James M.; Benedict, Stanley H.; Read, Paul W.; Sheng, Ke; Cai, Jing

2009-01-01

Cardiac-synchronized brain motion is well documented, but the accurate measurement of such motion on the pixel-by-pixel basis has been hampered by the lack of proper imaging technique. In this article, the authors present the implementation of an autotracking spiral cine displacement-encoded stimulation echo (DENSE) magnetic resonance imaging (MRI) technique for the measurement of pulsatile brain motion during the cardiac cycle. Displacement-encoded dynamic MR images of three healthy volunteers were acquired throughout the cardiac cycle using the spiral cine-DENSE pulse sequence gated to the R wave of an electrocardiogram. Pixelwise Lagrangian displacement maps were computed, and 2D displacement as a function of time was determined for selected regions of interests. Different intracranial structures exhibited characteristic motion amplitude, direction, and pattern throughout the cardiac cycle. Time-resolved displacement curves revealed the pathway of pulsatile motion from brain stem to peripheral brain lobes. These preliminary results demonstrated that the spiral cine-DENSE MRI technique can be used to measure cardiac-synchronized pulsatile brain motion on the pixel-by-pixel basis with high temporal∕spatial resolution and sensitivity. PMID:19746774

Improvement of cardiac CT reconstruction using local motion vector fields.

PubMed

Schirra, Carsten Oliver; Bontus, Claas; van Stevendaal, Udo; Dössel, Olaf; Grass, Michael

2009-03-01

The motion of the heart is a major challenge for cardiac imaging using CT. A novel approach to decrease motion blur and to improve the signal to noise ratio is motion compensated reconstruction which takes motion vector fields into account in order to correct motion. The presented work deals with the determination of local motion vector fields from high contrast objects and their utilization within motion compensated filtered back projection reconstruction. Image registration is applied during the quiescent cardiac phases. Temporal interpolation in parameter space is used in order to estimate motion during strong motion phases. The resulting motion vector fields are during image reconstruction. The method is assessed using a software phantom and several clinical cases for calcium scoring. As a criterion for reconstruction quality, calcium volume scores were derived from both, gated cardiac reconstruction and motion compensated reconstruction throughout the cardiac phases using low pitch helical cone beam CT acquisitions. The presented technique is a robust method to determine and utilize local motion vector fields. Motion compensated reconstruction using the derived motion vector fields leads to superior image quality compared to gated reconstruction. As a result, the gating window can be enlarged significantly, resulting in increased SNR, while reliable Hounsfield units are achieved due to the reduced level of motion artefacts. The enlargement of the gating window can be translated into reduced dose requirements.

Temporally diffeomorphic cardiac motion estimation from three-dimensional echocardiography by minimization of intensity consistency error.

PubMed

Zhang, Zhijun; Ashraf, Muhammad; Sahn, David J; Song, Xubo

2014-05-01

Quantitative analysis of cardiac motion is important for evaluation of heart function. Three dimensional (3D) echocardiography is among the most frequently used imaging modalities for motion estimation because it is convenient, real-time, low-cost, and nonionizing. However, motion estimation from 3D echocardiographic sequences is still a challenging problem due to low image quality and image corruption by noise and artifacts. The authors have developed a temporally diffeomorphic motion estimation approach in which the velocity field instead of the displacement field was optimized. The optimal velocity field optimizes a novel similarity function, which we call the intensity consistency error, defined as multiple consecutive frames evolving to each time point. The optimization problem is solved by using the steepest descent method. Experiments with simulated datasets, images of anex vivo rabbit phantom, images of in vivo open-chest pig hearts, and healthy human images were used to validate the authors' method. Simulated and real cardiac sequences tests showed that results in the authors' method are more accurate than other competing temporal diffeomorphic methods. Tests with sonomicrometry showed that the tracked crystal positions have good agreement with ground truth and the authors' method has higher accuracy than the temporal diffeomorphic free-form deformation (TDFFD) method. Validation with an open-access human cardiac dataset showed that the authors' method has smaller feature tracking errors than both TDFFD and frame-to-frame methods. The authors proposed a diffeomorphic motion estimation method with temporal smoothness by constraining the velocity field to have maximum local intensity consistency within multiple consecutive frames. The estimated motion using the authors' method has good temporal consistency and is more accurate than other temporally diffeomorphic motion estimation methods.

Molecular Dynamics Simulation Reveals Correlated Inter-Lobe Motion in Protein Lysine Methyltransferase SMYD2.

PubMed

Spellmon, Nicholas; Sun, Xiaonan; Sirinupong, Nualpun; Edwards, Brian; Li, Chunying; Yang, Zhe

2015-01-01

SMYD proteins are an exciting field of study as they are linked to many types of cancer-related pathways. Cardiac and skeletal muscle development and function also depend on SMYD proteins opening a possible avenue for cardiac-related treatment. Previous crystal structure studies have revealed that this special class of protein lysine methyltransferases have a bilobal structure, and an open-closed motion may regulate substrate specificity. Here we use the molecular dynamics simulation to investigate the still-poorly-understood SMYD2 dynamics. Cross-correlation analysis reveals that SMYD2 exhibits a negative correlated inter-lobe motion. Principle component analysis suggests that this correlated dynamic is contributed to by a twisting motion of the C-lobe with respect to the N-lobe and a clamshell-like motion between the lobes. Dynamical network analysis defines possible allosteric paths for the correlated dynamics. There are nine communities in the dynamical network with six in the N-lobe and three in the C-lobe, and the communication between the lobes is mediated by a lobe-bridging β hairpin. This study provides insight into the dynamical nature of SMYD2 and could facilitate better understanding of SMYD2 substrate specificity.

Automated classification of LV regional wall motion based on spatio-temporal profiles from cardiac cine magnetic resonance imaging

NASA Astrophysics Data System (ADS)

Mantilla, Juan; Garreau, Mireille; Bellanger, Jean-Jacques; Paredes, José Luis

2013-11-01

Assessment of the cardiac Left Ventricle (LV) wall motion is generally based on visual inspection or quantitative analysis of 2D+t sequences acquired in short-axis cardiac cine-Magnetic Resonance Imaging (MRI). Most often, cardiac dynamic is globally analized from two particular phases of the cardiac cycle. In this paper, we propose an automated method to classify regional wall motion in LV function based on spatio-temporal pro les and Support Vector Machines (SVM). This approach allows to obtain a binary classi cation between normal and abnormal motion, without the need of pre-processing and by exploiting all the images of the cardiac cycle. In each short- axis MRI slice level (basal, median, and apical), the spatio-temporal pro les are extracted from the selection of a subset of diametrical lines crossing opposites LV segments. Initialized at end-diastole phase, the pro les are concatenated with their corresponding projections into the succesive temporal phases of the cardiac cycle. These pro les are associated to di erent types of information that derive from the image (gray levels), Fourier, Wavelet or Curvelet domains. The approach has been tested on a set of 14 abnormal and 6 healthy patients by using a leave-one-out cross validation and two kernel functions for SVM classi er. The best classi cation performance is yielded by using four-level db4 wavelet transform and SVM with a linear kernel. At each slice level the results provided a classi cation rate of 87.14% in apical level, 95.48% in median level and 93.65% in basal level.

Cardiac Magnetic Resonance Imaging for the Diagnosis of Coronary Artery Disease

PubMed Central

2010-01-01

Executive Summary In July 2009, the Medical Advisory Secretariat (MAS) began work on Non-Invasive Cardiac Imaging Technologies for the Diagnosis of Coronary Artery Disease (CAD), an evidence-based review of the literature surrounding different cardiac imaging modalities to ensure that appropriate technologies are accessed by patients suspected of having CAD. This project came about when the Health Services Branch at the Ministry of Health and Long-Term Care asked MAS to provide an evidentiary platform on effectiveness and cost-effectiveness of non-invasive cardiac imaging modalities. After an initial review of the strategy and consultation with experts, MAS identified five key non-invasive cardiac imaging technologies for the diagnosis of CAD. Evidence-based analyses have been prepared for each of these five imaging modalities: cardiac magnetic resonance imaging, single photon emission computed tomography, 64-slice computed tomographic angiography, stress echocardiography, and stress echocardiography with contrast. For each technology, an economic analysis was also completed (where appropriate). A summary decision analytic model was then developed to encapsulate the data from each of these reports (available on the OHTAC and MAS website). The Non-Invasive Cardiac Imaging Technologies for the Diagnosis of Coronary Artery Disease series is made up of the following reports, which can be publicly accessed at the MAS website at: www.health.gov.on.ca/mas or at www.health.gov.on.ca/english/providers/program/mas/mas_about.html Single Photon Emission Computed Tomography for the Diagnosis of Coronary Artery Disease: An Evidence-Based Analysis Stress Echocardiography for the Diagnosis of Coronary Artery Disease: An Evidence-Based Analysis Stress Echocardiography with Contrast for the Diagnosis of Coronary Artery Disease: An Evidence-Based Analysis 64-Slice Computed Tomographic Angiography for the Diagnosis of Coronary Artery Disease: An Evidence-Based Analysis Cardiac Magnetic Resonance Imaging for the Diagnosis of Coronary Artery Disease: An Evidence-Based Analysis Pease note that two related evidence-based analyses of non-invasive cardiac imaging technologies for the assessment of myocardial viability are also available on the MAS website: Positron Emission Tomography for the Assessment of Myocardial Viability: An Evidence-Based Analysis Magnetic Resonance Imaging for the Assessment of Myocardial Viability: an Evidence-Based Analysis The Toronto Health Economics and Technology Assessment Collaborative has also produced an associated economic report entitled: The Relative Cost-effectiveness of Five Non-invasive Cardiac Imaging Technologies for Diagnosing Coronary Artery Disease in Ontario [Internet]. Available from: http://theta.utoronto.ca/reports/?id=7 Objective The objective of this analysis was to determine the diagnostic accuracy of cardiac magnetic resonance imaging (MRI) for the diagnosis of patients with known/suspected coronary artery disease (CAD) compared to coronary angiography. Cardiac MRI Stress cardiac MRI is a non-invasive, x-ray free imaging technique that takes approximately 30 to 45 minutes to complete and can be performed using to two different methods, a) perfusion imaging following a first pass of an intravenous bolus of gadolinium contrast, or b) wall motion imaging. Stress is induced pharmacologically with either dobutamine, dipyridamole, or adenosine, as physical exercise is difficult to perform within the magnet bore and often induces motion artifacts. Alternatives to stress cardiac perfusion MRI include stress single-photon emission computed tomography (SPECT) and stress echocardiography (ECHO). The advantage of cardiac MRI is that it does not pose the radiation burden associated with SPECT. During the same sitting, cardiac MRI can also assess left and right ventricular dimensions, viability, and cardiac mass. It may also mitigate the need for invasive diagnostic coronary angiography in patients with intermediate risk factors for CAD. Evidence-Based Analysis Literature Search A literature search was performed on October 9, 2009 using OVID MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, the Cumulative Index to Nursing & Allied Health Literature (CINAHL), the Cochrane Library, and the International Agency for Health Technology Assessment (INAHTA) for studies published from January 1, 2005 to October 9, 2008. Abstracts were reviewed by a single reviewer and, for those studies meeting the eligibility criteria, full-text articles were obtained. Reference lists were also examined for any relevant studies not identified through the search. Articles with unknown eligibility were reviewed with a second clinical epidemiologist and then a group of epidemiologists until consensus was established. The quality of evidence was assessed as high, moderate, low or very low according to GRADE methodology. Given the large amount of clinical heterogeneity of the articles meeting the inclusion criteria, as well as suggestions from an Expert Advisory Panel Meeting held on October 5, 2009, the inclusion criteria were revised to examine the effectiveness of cardiac MRI for the detection of CAD. Inclusion Criteria Exclusion Criteria Heath technology assessments, systematic reviews, randomized controlled trials, observational studies ≥20 adult patients enrolled. Published 2004-2009 Licensed by Health Canada For diagnosis of CAD: Reference standard is coronary angiography Significant CAD defined as ≥ 50% coronary stenosis Patients with suspected or known CAD Reported results by patient, not segment Non-English studies Grey literature Planar imaging MUGA Patients with recent MI (i.e., within 1 month) Patients with non-ischemic heart disease Studies done exclusively in special populations (e.g., women, diabetics) Outcomes of Interest Sensitivity and specificity Area under the curve (AUC) Diagnostic odds ratio (DOR) Summary of Findings Stress cardiac MRI using perfusion analysis yielded a pooled sensitivity of 0.91 (95% CI: 0.89 to 0.92) and specificity of 0.79 (95% CI: 0.76 to 0.82) for the detection of CAD. Stress cardiac MRI using wall motion analysis yielded a pooled sensitivity of 0.81 (95% CI: 0.77 to 0.84) and specificity of 0.85 (95% CI: 0.81 to 0.89) for the detection of CAD. Based on DORs, there was no significant difference between pooled stress cardiac MRI using perfusion analysis and pooled stress cardiac MRI using wall motion analysis (P=0.26) for the detection of CAD. Pooled subgroup analysis of stress cardiac MRI using perfusion analysis showed no significant difference in the DORs between 1.5T and 3T MRI (P=0.72) for the detection of CAD. One study (N=60) was identified that examined stress cardiac MRI using wall motion analysis with a 3T MRI. The sensitivity and specificity of 3T MRI were 0.64 (95% CI: 0.44 to 0.81) and 1.00 (95% CI: 0.89 to 1.00), respectively, for the detection of CAD. The effectiveness of stress cardiac MRI for the detection of CAD in unstable patients with acute coronary syndrome was reported in only one study (N=35). Using perfusion analysis, the sensitivity and specificity were 0.72 (95% CI: 0.53 to 0.87) and 1.00 (95% CI: 0.54 to 1.00), respectively, for the detection of CAD. Ontario Health System Impact Analysis According to an expert consultant, in Ontario: Stress first pass perfusion is currently performed in small numbers in London (London Health Sciences Centre) and Toronto (University Health Network at the Toronto General Hospital site and Sunnybrook Health Sciences Centre). Stress wall motion is only performed as part of research protocols and not very often. Cardiac MRI machines use 1.5T almost exclusively, with 3T used in research for first pass perfusion. On November 25 2009, the Cardiac Imaging Expert Advisory Panel met and made the following comments about stress cardiac MRI for perfusion analysis: Accessibility to cardiac MRI is limited and generally used to assess structural abnormalities. Most MRIs in Ontario are already in 24–hour, constant use and it would thus be difficult to add cardiac MRI for CAD diagnosis as an additional indication. The performance of cardiac MRI for the diagnosis of CAD can be technically challenging. GRADE Quality of Evidence for Cardiac MRI in the Diagnosis of CAD The quality of the body of evidence was assessed according to the GRADE Working Group criteria for diagnostic tests. For perfusion analysis, the overall quality was determined to be low and for wall motion analysis the overall quality was very low. PMID:23074389

Cardiac magnetic resonance imaging for the diagnosis of coronary artery disease: an evidence-based analysis.

PubMed

2010-01-01

In July 2009, the Medical Advisory Secretariat (MAS) began work on Non-Invasive Cardiac Imaging Technologies for the Diagnosis of Coronary Artery Disease (CAD), an evidence-based review of the literature surrounding different cardiac imaging modalities to ensure that appropriate technologies are accessed by patients suspected of having CAD. This project came about when the Health Services Branch at the Ministry of Health and Long-Term Care asked MAS to provide an evidentiary platform on effectiveness and cost-effectiveness of non-invasive cardiac imaging modalities.After an initial review of the strategy and consultation with experts, MAS identified five key non-invasive cardiac imaging technologies for the diagnosis of CAD. Evidence-based analyses have been prepared for each of these five imaging modalities: cardiac magnetic resonance imaging, single photon emission computed tomography, 64-slice computed tomographic angiography, stress echocardiography, and stress echocardiography with contrast. For each technology, an economic analysis was also completed (where appropriate). A summary decision analytic model was then developed to encapsulate the data from each of these reports (available on the OHTAC and MAS website).The Non-Invasive Cardiac Imaging Technologies for the Diagnosis of Coronary Artery Disease series is made up of the following reports, which can be publicly accessed at the MAS website at: www.health.gov.on.ca/mas or at www.health.gov.on.ca/english/providers/program/mas/mas_about.htmlSINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY FOR THE DIAGNOSIS OF CORONARY ARTERY DISEASE: An Evidence-Based AnalysisSTRESS ECHOCARDIOGRAPHY FOR THE DIAGNOSIS OF CORONARY ARTERY DISEASE: An Evidence-Based AnalysisSTRESS ECHOCARDIOGRAPHY WITH CONTRAST FOR THE DIAGNOSIS OF CORONARY ARTERY DISEASE: An Evidence-Based Analysis64-Slice Computed Tomographic Angiography for the Diagnosis of Coronary Artery Disease: An Evidence-Based AnalysisCARDIAC MAGNETIC RESONANCE IMAGING FOR THE DIAGNOSIS OF CORONARY ARTERY DISEASE: An Evidence-Based AnalysisPease note that two related evidence-based analyses of non-invasive cardiac imaging technologies for the assessment of myocardial viability are also available on the MAS website:POSITRON EMISSION TOMOGRAPHY FOR THE ASSESSMENT OF MYOCARDIAL VIABILITY: An Evidence-Based AnalysisMAGNETIC RESONANCE IMAGING FOR THE ASSESSMENT OF MYOCARDIAL VIABILITY: an Evidence-Based AnalysisThe Toronto Health Economics and Technology Assessment Collaborative has also produced an associated economic report entitled:The Relative Cost-effectiveness of Five Non-invasive Cardiac Imaging Technologies for Diagnosing Coronary Artery Disease in Ontario [Internet]. Available from: http://theta.utoronto.ca/reports/?id=7 OBJECTIVE: The objective of this analysis was to determine the diagnostic accuracy of cardiac magnetic resonance imaging (MRI) for the diagnosis of patients with known/suspected coronary artery disease (CAD) compared to coronary angiography. Stress cardiac MRI is a non-invasive, x-ray free imaging technique that takes approximately 30 to 45 minutes to complete and can be performed using to two different methods, a) perfusion imaging following a first pass of an intravenous bolus of gadolinium contrast, or b) wall motion imaging. Stress is induced pharmacologically with either dobutamine, dipyridamole, or adenosine, as physical exercise is difficult to perform within the magnet bore and often induces motion artifacts. Alternatives to stress cardiac perfusion MRI include stress single-photon emission computed tomography (SPECT) and stress echocardiography (ECHO). The advantage of cardiac MRI is that it does not pose the radiation burden associated with SPECT. During the same sitting, cardiac MRI can also assess left and right ventricular dimensions, viability, and cardiac mass. It may also mitigate the need for invasive diagnostic coronary angiography in patients with intermediate risk factors for CAD. EVIDENCE-BASED ANALYSIS: A literature search was performed on October 9, 2009 using OVID MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, the Cumulative Index to Nursing & Allied Health Literature (CINAHL), the Cochrane Library, and the International Agency for Health Technology Assessment (INAHTA) for studies published from January 1, 2005 to October 9, 2008. Abstracts were reviewed by a single reviewer and, for those studies meeting the eligibility criteria, full-text articles were obtained. Reference lists were also examined for any relevant studies not identified through the search. Articles with unknown eligibility were reviewed with a second clinical epidemiologist and then a group of epidemiologists until consensus was established. The quality of evidence was assessed as high, moderate, low or very low according to GRADE methodology. Given the large amount of clinical heterogeneity of the articles meeting the inclusion criteria, as well as suggestions from an Expert Advisory Panel Meeting held on October 5, 2009, the inclusion criteria were revised to examine the effectiveness of cardiac MRI for the detection of CAD. Inclusion CriteriaExclusion CriteriaHeath technology assessments, systematic reviews, randomized controlled trials, observational studies≥20 adult patients enrolled.Published 2004-2009Licensed by Health CanadaFor diagnosis of CAD:Reference standard is coronary angiographySignificant CAD defined as ≥ 50% coronary stenosisPatients with suspected or known CADReported results by patient, not segmentNon-English studiesGrey literaturePlanar imagingMUGAPatients with recent MI (i.e., within 1 month)Patients with non-ischemic heart diseaseStudies done exclusively in special populations (e.g., women, diabetics) Sensitivity and specificityArea under the curve (AUC)Diagnostic odds ratio (DOR) SUMMARY OF FINDINGS: Stress cardiac MRI using perfusion analysis yielded a pooled sensitivity of 0.91 (95% CI: 0.89 to 0.92) and specificity of 0.79 (95% CI: 0.76 to 0.82) for the detection of CAD.Stress cardiac MRI using wall motion analysis yielded a pooled sensitivity of 0.81 (95% CI: 0.77 to 0.84) and specificity of 0.85 (95% CI: 0.81 to 0.89) for the detection of CAD.Based on DORs, there was no significant difference between pooled stress cardiac MRI using perfusion analysis and pooled stress cardiac MRI using wall motion analysis (P=0.26) for the detection of CAD.Pooled subgroup analysis of stress cardiac MRI using perfusion analysis showed no significant difference in the DORs between 1.5T and 3T MRI (P=0.72) for the detection of CAD.One study (N=60) was identified that examined stress cardiac MRI using wall motion analysis with a 3T MRI. The sensitivity and specificity of 3T MRI were 0.64 (95% CI: 0.44 to 0.81) and 1.00 (95% CI: 0.89 to 1.00), respectively, for the detection of CAD.The effectiveness of stress cardiac MRI for the detection of CAD in unstable patients with acute coronary syndrome was reported in only one study (N=35). Using perfusion analysis, the sensitivity and specificity were 0.72 (95% CI: 0.53 to 0.87) and 1.00 (95% CI: 0.54 to 1.00), respectively, for the detection of CAD. According to an expert consultant, in Ontario: Stress first pass perfusion is currently performed in small numbers in London (London Health Sciences Centre) and Toronto (University Health Network at the Toronto General Hospital site and Sunnybrook Health Sciences Centre).Stress wall motion is only performed as part of research protocols and not very often.Cardiac MRI machines use 1.5T almost exclusively, with 3T used in research for first pass perfusion.On November 25 2009, the Cardiac Imaging Expert Advisory Panel met and made the following comments about stress cardiac MRI for perfusion analysis: Accessibility to cardiac MRI is limited and generally used to assess structural abnormalities. Most MRIs in Ontario are already in 24-hour, constant use and it would thus be difficult to add cardiac MRI for CAD diagnosis as an additional indication.The performance of cardiac MRI for the diagnosis of CAD can be technically challenging. The quality of the body of evidence was assessed according to the GRADE Working Group criteria for diagnostic tests. For perfusion analysis, the overall quality was determined to be low and for wall motion analysis the overall quality was very low.

Evaluation of motion-correction methods for dual-gated cardiac positron emission tomography/computed tomography imaging.

PubMed

Klén, Riku; Noponen, Tommi; Koikkalainen, Juha; Lötjönen, Jyrki; Thielemans, Kris; Hoppela, Erika; Sipilä, Hannu; Teräs, Mika; Knuuti, Juhani

2016-09-01

Dual gating is a method of dividing the data of a cardiac PET scan into smaller bins according to the respiratory motion and the ECG of the patient. It reduces the undesirable motion artefacts in images, but produces several images for interpretation and decreases the quality of single images. By using motion-correction techniques, the motion artefacts in the dual-gated images can be corrected and the images can be combined into a single motion-free image with good statistics. The aim of the present study is to develop and evaluate motion-correction methods for cardiac PET studies. We have developed and compared two different methods: computed tomography (CT)/PET-based and CT-only methods. The methods were implemented and tested with a cardiac phantom and three patient datasets. In both methods, anatomical information of CT images is used to create models for the cardiac motion. In the patient study, the CT-only method reduced motion (measured as the centre of mass of the myocardium) on average 43%, increased the contrast-to-noise ratio on average 6.0% and reduced the target size on average 10%. Slightly better figures (51, 6.9 and 28%) were obtained with the CT/PET-based method. Even better results were obtained in the phantom study for both the CT-only method (57, 68 and 43%) and the CT/PET-based method (61, 74 and 52%). We conclude that using anatomical information of CT for motion correction of cardiac PET images, both respiratory and pulsatile motions can be corrected with good accuracy.

Human torso phantom for imaging of heart with realistic modes of cardiac and respiratory motion

DOEpatents

Boutchko, Rostyslav; Balakrishnan, Karthikayan; Gullberg, Grant T; O& #x27; Neil, James P

2013-09-17

A human torso phantom and its construction, wherein the phantom mimics respiratory and cardiac cycles in a human allowing acquisition of medical imaging data under conditions simulating patient cardiac and respiratory motion.

Annular dynamics of memo3D annuloplasty ring evaluated by 3D transesophageal echocardiography.

PubMed

Nishi, Hiroyuki; Toda, Koichi; Miyagawa, Shigeru; Yoshikawa, Yasushi; Fukushima, Satsuki; Yoshioka, Daisuke; Sawa, Yoshiki

2018-04-01

We assessed the mitral annular motion after mitral valve repair with the Sorin Memo 3D® (Sorin Group Italia S.r.L., Saluggia, Italy), which is a unique complete semirigid annuloplasty ring intended to restore the systolic profile of the mitral annulus while adapting to the physiologic dynamism of the annulus, using transesophageal real-time three-dimensional echocardiography. 17 patients (12 male; mean age 60.4 ± 14.9 years) who underwent mitral annuloplasty using the Memo 3D ring were investigated. Mitral annular motion was assessed using QLAB®version8 allowing for a full evaluation of the mitral annulus dynamics. The mitral annular dimensions were measured throughout the cardiac cycle using 4D MV assessment2® while saddle shape was assessed through sequential measurements by RealView®. Saddle shape configuration of the mitral annulus and posterior and anterior leaflet motion could be observed during systole and diastole. The mitral annular area changed during the cardiac cycle by 5.7 ± 1.8%.The circumference length and diameter also changed throughout the cardiac cycle. The annular height was significantly higher in mid-systole than in mid-diastole (p < 0.05). The Memo 3D ring maintained a physiological saddle-shape configuration throughout the cardiac cycle. Real-time three-dimensional echocardiography analysis confirmed the motion and flexibility of the Memo 3D ring upon implantation.

False dyssynchrony: problem with image-based cardiac functional analysis using x-ray computed tomography

NASA Astrophysics Data System (ADS)

Kidoh, Masafumi; Shen, Zeyang; Suzuki, Yuki; Ciuffo, Luisa; Ashikaga, Hiroshi; Fung, George S. K.; Otake, Yoshito; Zimmerman, Stefan L.; Lima, Joao A. C.; Higuchi, Takahiro; Lee, Okkyun; Sato, Yoshinobu; Becker, Lewis C.; Fishman, Elliot K.; Taguchi, Katsuyuki

2017-03-01

We have developed a digitally synthesized patient which we call "Zach" (Zero millisecond Adjustable Clinical Heart) phantom, which allows for an access to the ground truth and assessment of image-based cardiac functional analysis (CFA) using CT images with clinically realistic settings. The study using Zach phantom revealed a major problem with image-based CFA: "False dyssynchrony." Even though the true motion of wall segments is in synchrony, it may appear to be dyssynchrony with the reconstructed cardiac CT images. It is attributed to how cardiac images are reconstructed and how wall locations are updated over cardiac phases. The presence and the degree of false dyssynchrony may vary from scan-to-scan, which could degrade the accuracy and the repeatability (or precision) of image-based CT-CFA exams.

Directional analysis of cardiac motion field from gated fluorodeoxyglucose PET images using the Discrete Helmholtz Hodge Decomposition.

PubMed

Sims, J A; Giorgi, M C; Oliveira, M A; Meneghetti, J C; Gutierrez, M A

2018-04-01

Extract directional information related to left ventricular (LV) rotation and torsion from a 4D PET motion field using the Discrete Helmholtz Hodge Decomposition (DHHD). Synthetic motion fields were created using superposition of rotational and radial field components and cardiac fields produced using optical flow from a control and patient image. These were decomposed into curl-free (CF) and divergence-free (DF) components using the DHHD. Synthetic radial components were present in the CF field and synthetic rotational components in the DF field, with each retaining its center position, direction of motion and diameter after decomposition. Direction of rotation at apex and base for the control field were in opposite directions during systole, reversing during diastole. The patient DF field had little overall rotation with several small rotators. The decomposition of the LV motion field into directional components could assist quantification of LV torsion, but further processing stages seem necessary. Copyright © 2017 Elsevier Ltd. All rights reserved.

4D motion modeling of the coronary arteries from CT images for robotic assisted minimally invasive surgery

NASA Astrophysics Data System (ADS)

Zhang, Dong Ping; Edwards, Eddie; Mei, Lin; Rueckert, Daniel

2009-02-01

In this paper, we present a novel approach for coronary artery motion modeling from cardiac Computed Tomography( CT) images. The aim of this work is to develop a 4D motion model of the coronaries for image guidance in robotic-assisted totally endoscopic coronary artery bypass (TECAB) surgery. To utilize the pre-operative cardiac images to guide the minimally invasive surgery, it is essential to have a 4D cardiac motion model to be registered with the stereo endoscopic images acquired intraoperatively using the da Vinci robotic system. In this paper, we are investigating the extraction of the coronary arteries and the modelling of their motion from a dynamic sequence of cardiac CT. We use a multi-scale vesselness filter to enhance vessels in the cardiac CT images. The centerlines of the arteries are extracted using a ridge traversal algorithm. Using this method the coronaries can be extracted in near real-time as only local information is used in vessel tracking. To compute the deformation of the coronaries due to cardiac motion, the motion is extracted from a dynamic sequence of cardiac CT. Each timeframe in this sequence is registered to the end-diastole timeframe of the sequence using a non-rigid registration algorithm based on free-form deformations. Once the images have been registered a dynamic motion model of the coronaries can be obtained by applying the computed free-form deformations to the extracted coronary arteries. To validate the accuracy of the motion model we compare the actual position of the coronaries in each time frame with the predicted position of the coronaries as estimated from the non-rigid registration. We expect that this motion model of coronaries can facilitate the planning of TECAB surgery, and through the registration with real-time endoscopic video images it can reduce the conversion rate from TECAB to conventional procedures.

Real-Time Three-Dimensional Echocardiography: Characterization of Cardiac Anatomy and Function-Current Clinical Applications and Literature Review Update.

PubMed

Velasco, Omar; Beckett, Morgan Q; James, Aaron W; Loehr, Megan N; Lewis, Taylor G; Hassan, Tahmin; Janardhanan, Rajesh

2017-01-01

Our review of real-time three-dimensional echocardiography (RT3DE) discusses the diagnostic utility of RT3DE and provides a comparison with two-dimensional echocardiography (2DE) in clinical cardiology. A Pubmed literature search on RT3DE was performed using the following key words: transthoracic, two-dimensional, three-dimensional, real-time, and left ventricular (LV) function. Articles included perspective clinical studies and meta-analyses in the English language, and focused on the role of RT3DE in human subjects. Application of RT3DE includes analysis of the pericardium, right ventricular (RV) and LV cavities, wall motion, valvular disease, great vessels, congenital anomalies, and traumatic injury, such as myocardial contusion. RT3DE, through a transthoracic echocardiography (TTE), allows for increasingly accurate volume and valve motion assessment, estimated LV ejection fraction, and volume measurements. Chamber motion and LV mass approximation have been more accurately evaluated by RT3DE by improved inclusion of the third dimension and quantification of volumetric movement. Moreover, RT3DE was shown to have no statistical significance when comparing the ejection fractions of RT3DE to cardiac magnetic resonance (CMR). Analysis of RT3DE data sets of the LV endocardial exterior allows for the volume to be directly quantified for specific phases of the cardiac cycle, ranging from end systole to end diastole, eliminating error from wall motion abnormalities and asymmetrical left ventricles. RT3DE through TTE measures cardiac function with superior diagnostic accuracy in predicting LV mass, systolic function, along with LV and RV volume when compared with 2DE with comparable results to CMR.

Enhancing ejection fraction measurement through 4D respiratory motion compensation in cardiac PET imaging

NASA Astrophysics Data System (ADS)

Tang, Jing; Wang, Xinhui; Gao, Xiangzhen; Segars, W. Paul; Lodge, Martin A.; Rahmim, Arman

2017-06-01

ECG gated cardiac PET imaging measures functional parameters such as left ventricle (LV) ejection fraction (EF), providing diagnostic and prognostic information for management of patients with coronary artery disease (CAD). Respiratory motion degrades spatial resolution and affects the accuracy in measuring the LV volumes for EF calculation. The goal of this study is to systematically investigate the effect of respiratory motion correction on the estimation of end-diastolic volume (EDV), end-systolic volume (ESV), and EF, especially on the separation of normal and abnormal EFs. We developed a respiratory motion incorporated 4D PET image reconstruction technique which uses all gated-frame data to acquire a motion-suppressed image. Using the standard XCAT phantom and two individual-specific volunteer XCAT phantoms, we simulated dual-gated myocardial perfusion imaging data for normally and abnormally beating hearts. With and without respiratory motion correction, we measured the EDV, ESV, and EF from the cardiac-gated reconstructed images. For all the phantoms, the estimated volumes increased and the biases significantly reduced with motion correction compared with those without. Furthermore, the improvement of ESV measurement in the abnormally beating heart led to better separation of normal and abnormal EFs. The simulation study demonstrated the significant effect of respiratory motion correction on cardiac imaging data with motion amplitude as small as 0.7 cm. The larger the motion amplitude the more improvement respiratory motion correction brought about on the EF measurement. Using data-driven respiratory gating, we also demonstrated the effect of respiratory motion correction on estimating the above functional parameters from list mode patient data. Respiratory motion correction has been shown to improve the accuracy of EF measurement in clinical cardiac PET imaging.

Five-dimensional motion compensation for respiratory and cardiac motion with cone-beam CT of the thorax region

NASA Astrophysics Data System (ADS)

Sauppe, Sebastian; Hahn, Andreas; Brehm, Marcus; Paysan, Pascal; Seghers, Dieter; Kachelrieß, Marc

2016-03-01

We propose an adapted method of our previously published five-dimensional (5D) motion compensation (MoCo) algorithm1, developed for micro-CT imaging of small animals, to provide for the first time motion artifact-free 5D cone-beam CT (CBCT) images from a conventional flat detector-based CBCT scan of clinical patients. Image quality of retrospectively respiratory- and cardiac-gated volumes from flat detector CBCT scans is deteriorated by severe sparse projection artifacts. These artifacts further complicate motion estimation, as it is required for MoCo image reconstruction. For high quality 5D CBCT images at the same x-ray dose and the same number of projections as todays 3D CBCT we developed a double MoCo approach based on motion vector fields (MVFs) for respiratory and cardiac motion. In a first step our already published four-dimensional (4D) artifact-specific cyclic motion-compensation (acMoCo) approach is applied to compensate for the respiratory patient motion. With this information a cyclic phase-gated deformable heart registration algorithm is applied to the respiratory motion-compensated 4D CBCT data, thus resulting in cardiac MVFs. We apply these MVFs on double-gated images and thereby respiratory and cardiac motion-compensated 5D CBCT images are obtained. Our 5D MoCo approach processing patient data acquired with the TrueBeam 4D CBCT system (Varian Medical Systems). Our double MoCo approach turned out to be very efficient and removed nearly all streak artifacts due to making use of 100% of the projection data for each reconstructed frame. The 5D MoCo patient data show fine details and no motion blurring, even in regions close to the heart where motion is fastest.

XD-GRASP: Golden-angle radial MRI with reconstruction of extra motion-state dimensions using compressed sensing.

PubMed

Feng, Li; Axel, Leon; Chandarana, Hersh; Block, Kai Tobias; Sodickson, Daniel K; Otazo, Ricardo

2016-02-01

To develop a novel framework for free-breathing MRI called XD-GRASP, which sorts dynamic data into extra motion-state dimensions using the self-navigation properties of radial imaging and reconstructs the multidimensional dataset using compressed sensing. Radial k-space data are continuously acquired using the golden-angle sampling scheme and sorted into multiple motion-states based on respiratory and/or cardiac motion signals derived directly from the data. The resulting undersampled multidimensional dataset is reconstructed using a compressed sensing approach that exploits sparsity along the new dynamic dimensions. The performance of XD-GRASP is demonstrated for free-breathing three-dimensional (3D) abdominal imaging, two-dimensional (2D) cardiac cine imaging and 3D dynamic contrast-enhanced (DCE) MRI of the liver, comparing against reconstructions without motion sorting in both healthy volunteers and patients. XD-GRASP separates respiratory motion from cardiac motion in cardiac imaging, and respiratory motion from contrast enhancement in liver DCE-MRI, which improves image quality and reduces motion-blurring artifacts. XD-GRASP represents a new use of sparsity for motion compensation and a novel way to handle motions in the context of a continuous acquisition paradigm. Instead of removing or correcting motion, extra motion-state dimensions are reconstructed, which improves image quality and also offers new physiological information of potential clinical value. © 2015 Wiley Periodicals, Inc.

XD-GRASP: Golden-Angle Radial MRI with Reconstruction of Extra Motion-State Dimensions Using Compressed Sensing

PubMed Central

Feng, Li; Axel, Leon; Chandarana, Hersh; Block, Kai Tobias; Sodickson, Daniel K.; Otazo, Ricardo

2015-01-01

Purpose To develop a novel framework for free-breathing MRI called XD-GRASP, which sorts dynamic data into extra motion-state dimensions using the self-navigation properties of radial imaging and reconstructs the multidimensional dataset using compressed sensing. Methods Radial k-space data are continuously acquired using the golden-angle sampling scheme and sorted into multiple motion-states based on respiratory and/or cardiac motion signals derived directly from the data. The resulting under-sampled multidimensional dataset is reconstructed using a compressed sensing approach that exploits sparsity along the new dynamic dimensions. The performance of XD-GRASP is demonstrated for free-breathing three-dimensional (3D) abdominal imaging, two-dimensional (2D) cardiac cine imaging and 3D dynamic contrast-enhanced (DCE) MRI of the liver, comparing against reconstructions without motion sorting in both healthy volunteers and patients. Results XD-GRASP separates respiratory motion from cardiac motion in cardiac imaging, and respiratory motion from contrast enhancement in liver DCE-MRI, which improves image quality and reduces motion-blurring artifacts. Conclusion XD-GRASP represents a new use of sparsity for motion compensation and a novel way to handle motions in the context of a continuous acquisition paradigm. Instead of removing or correcting motion, extra motion-state dimensions are reconstructed, which improves image quality and also offers new physiological information of potential clinical value. PMID:25809847

A priori motion models for four-dimensional reconstruction in gated cardiac SPECT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lalush, D.S.; Tsui, B.M.W.; Cui, Lin

1996-12-31

We investigate the benefit of incorporating a priori assumptions about cardiac motion in a fully four-dimensional (4D) reconstruction algorithm for gated cardiac SPECT. Previous work has shown that non-motion-specific 4D Gibbs priors enforcing smoothing in time and space can control noise while preserving resolution. In this paper, we evaluate methods for incorporating known heart motion in the Gibbs prior model. The new model is derived by assigning motion vectors to each 4D voxel, defining the movement of that volume of activity into the neighboring time frames. Weights for the Gibbs cliques are computed based on these {open_quotes}most likely{close_quotes} motion vectors.more » To evaluate, we employ the mathematical cardiac-torso (MCAT) phantom with a new dynamic heart model that simulates the beating and twisting motion of the heart. Sixteen realistically-simulated gated datasets were generated, with noise simulated to emulate a real Tl-201 gated SPECT study. Reconstructions were performed using several different reconstruction algorithms, all modeling nonuniform attenuation and three-dimensional detector response. These include ML-EM with 4D filtering, 4D MAP-EM without prior motion assumption, and 4D MAP-EM with prior motion assumptions. The prior motion assumptions included both the correct motion model and incorrect models. Results show that reconstructions using the 4D prior model can smooth noise and preserve time-domain resolution more effectively than 4D linear filters. We conclude that modeling of motion in 4D reconstruction algorithms can be a powerful tool for smoothing noise and preserving temporal resolution in gated cardiac studies.« less

Higher-Order Motion-Compensation for In Vivo Cardiac Diffusion Tensor Imaging in Rats

PubMed Central

Welsh, Christopher L.; DiBella, Edward V. R.; Hsu, Edward W.

2015-01-01

Motion of the heart has complicated in vivo applications of cardiac diffusion MRI and diffusion tensor imaging (DTI), especially in small animals such as rats where ultra-high-performance gradient sets are currently not available. Even with velocity compensation via, for example, bipolar encoding pulses, the variable shot-to-shot residual motion-induced spin phase can still give rise to pronounced artifacts. This study presents diffusion-encoding schemes that are designed to compensate for higher-order motion components, including acceleration and jerk, which also have the desirable practical features of minimal TEs and high achievable b-values. The effectiveness of these schemes was verified numerically on a realistic beating heart phantom, and demonstrated empirically with in vivo cardiac diffusion MRI in rats. Compensation for acceleration, and lower motion components, was found to be both necessary and sufficient for obtaining diffusion-weighted images of acceptable quality and SNR, which yielded the first in vivo cardiac DTI demonstrated in the rat. These findings suggest that compensation for higher order motion, particularly acceleration, can be an effective alternative solution to high-performance gradient hardware for improving in vivo cardiac DTI. PMID:25775486

Atlas-based analysis of cardiac shape and function: correction of regional shape bias due to imaging protocol for population studies.

PubMed

Medrano-Gracia, Pau; Cowan, Brett R; Bluemke, David A; Finn, J Paul; Kadish, Alan H; Lee, Daniel C; Lima, Joao A C; Suinesiaputra, Avan; Young, Alistair A

2013-09-13

Cardiovascular imaging studies generate a wealth of data which is typically used only for individual study endpoints. By pooling data from multiple sources, quantitative comparisons can be made of regional wall motion abnormalities between different cohorts, enabling reuse of valuable data. Atlas-based analysis provides precise quantification of shape and motion differences between disease groups and normal subjects. However, subtle shape differences may arise due to differences in imaging protocol between studies. A mathematical model describing regional wall motion and shape was used to establish a coordinate system registered to the cardiac anatomy. The atlas was applied to data contributed to the Cardiac Atlas Project from two independent studies which used different imaging protocols: steady state free precession (SSFP) and gradient recalled echo (GRE) cardiovascular magnetic resonance (CMR). Shape bias due to imaging protocol was corrected using an atlas-based transformation which was generated from a set of 46 volunteers who were imaged with both protocols. Shape bias between GRE and SSFP was regionally variable, and was effectively removed using the atlas-based transformation. Global mass and volume bias was also corrected by this method. Regional shape differences between cohorts were more statistically significant after removing regional artifacts due to imaging protocol bias. Bias arising from imaging protocol can be both global and regional in nature, and is effectively corrected using an atlas-based transformation, enabling direct comparison of regional wall motion abnormalities between cohorts acquired in separate studies.

Registration Methods for IVUS: Transversal and Longitudinal Transducer Motion Compensation.

PubMed

Talou, Gonzalo D Maso; Blanco, Pablo J; Larrabide, Ignacio; Bezerra, Cristiano Guedes; Lemos, Pedro A; Feijoo, Raul A

2017-04-01

Intravascular ultrasound (IVUS) is a fundamental imaging technique for atherosclerotic plaque assessment, interventionist guidance, and, ultimately, as a tissue characterization tool. The studies acquired by this technique present the spatial description of the vessel during the cardiac cycle. However, the study frames are not properly sorted. As gating methods deal with the cardiac phase classification of the frames, the gated studies lack motion compensation between vessel and catheter. In this study, we develop registration strategies to arrange the vessel data into its rightful spatial sequence. Registration is performed by compensating longitudinal and transversal relative motion between vessel and catheter. Transversal motion is identified through maximum likelihood estimator optimization, while longitudinal motion is estimated by a neighborhood similarity estimator among the study frames. A strongly coupled implementation is proposed to compensate for both motion components at once. Loosely coupled implementations (DLT and DTL) decouple the registration process, resulting in more computationally efficient algorithms in detriment of the size of the set of candidate solutions. The DTL outperforms DLT and coupled implementations in terms of accuracy by a factor of 1.9 and 1.4, respectively. Sensitivity analysis shows that perivascular tissue must be considered to obtain the best registration outcome. Evidences suggest that the method is able to measure axial strain along the vessel wall. The proposed registration sorts the IVUS frames for spatial location, which is crucial for a correct interpretation of the vessel wall kinematics along the cardiac phases.

Radiotherapy beyond cancer: Target localization in real-time MRI and treatment planning for cardiac radiosurgery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ipsen, S.; Blanck, O.; Rades, D.

2014-12-15

Purpose: Atrial fibrillation (AFib) is the most common cardiac arrhythmia that affects millions of patients world-wide. AFib is usually treated with minimally invasive, time consuming catheter ablation techniques. While recently noninvasive radiosurgery to the pulmonary vein antrum (PVA) in the left atrium has been proposed for AFib treatment, precise target location during treatment is challenging due to complex respiratory and cardiac motion. A MRI linear accelerator (MRI-Linac) could solve the problems of motion tracking and compensation using real-time image guidance. In this study, the authors quantified target motion ranges on cardiac magnetic resonance imaging (MRI) and analyzed the dosimetric benefitsmore » of margin reduction assuming real-time motion compensation was applied. Methods: For the imaging study, six human subjects underwent real-time cardiac MRI under free breathing. The target motion was analyzed retrospectively using a template matching algorithm. The planning study was conducted on a CT of an AFib patient with a centrally located esophagus undergoing catheter ablation, representing an ideal case for cardiac radiosurgery. The target definition was similar to the ablation lesions at the PVA created during catheter treatment. Safety margins of 0 mm (perfect tracking) to 8 mm (untracked respiratory motion) were added to the target, defining the planning target volume (PTV). For each margin, a 30 Gy single fraction IMRT plan was generated. Additionally, the influence of 1 and 3 T magnetic fields on the treatment beam delivery was simulated using Monte Carlo calculations to determine the dosimetric impact of MRI guidance for two different Linac positions. Results: Real-time cardiac MRI showed mean respiratory target motion of 10.2 mm (superior–inferior), 2.4 mm (anterior–posterior), and 2 mm (left–right). The planning study showed that increasing safety margins to encompass untracked respiratory motion leads to overlapping structures even in the ideal scenario, compromising either normal tissue dose constraints or PTV coverage. The magnetic field caused a slight increase in the PTV dose with the in-line MRI-Linac configuration. Conclusions: The authors’ results indicate that real-time tracking and motion compensation are mandatory for cardiac radiosurgery and MRI-guidance is feasible, opening the possibility of treating cardiac arrhythmia patients completely noninvasively.« less

Improved workflow for quantification of left ventricular volumes and mass using free-breathing motion corrected cine imaging.

PubMed

Cross, Russell; Olivieri, Laura; O'Brien, Kendall; Kellman, Peter; Xue, Hui; Hansen, Michael

2016-02-25

Traditional cine imaging for cardiac functional assessment requires breath-holding, which can be problematic in some situations. Free-breathing techniques have relied on multiple averages or real-time imaging, producing images that can be spatially and/or temporally blurred. To overcome this, methods have been developed to acquire real-time images over multiple cardiac cycles, which are subsequently motion corrected and reformatted to yield a single image series displaying one cardiac cycle with high temporal and spatial resolution. Application of these algorithms has required significant additional reconstruction time. The use of distributed computing was recently proposed as a way to improve clinical workflow with such algorithms. In this study, we have deployed a distributed computing version of motion corrected re-binning reconstruction for free-breathing evaluation of cardiac function. Twenty five patients and 25 volunteers underwent cardiovascular magnetic resonance (CMR) for evaluation of left ventricular end-systolic volume (ESV), end-diastolic volume (EDV), and end-diastolic mass. Measurements using motion corrected re-binning were compared to those using breath-held SSFP and to free-breathing SSFP with multiple averages, and were performed by two independent observers. Pearson correlation coefficients and Bland-Altman plots tested agreement across techniques. Concordance correlation coefficient and Bland-Altman analysis tested inter-observer variability. Total scan plus reconstruction times were tested for significant differences using paired t-test. Measured volumes and mass obtained by motion corrected re-binning and by averaged free-breathing SSFP compared favorably to those obtained by breath-held SSFP (r = 0.9863/0.9813 for EDV, 0.9550/0.9685 for ESV, 0.9952/0.9771 for mass). Inter-observer variability was good with concordance correlation coefficients between observers across all acquisition types suggesting substantial agreement. Both motion corrected re-binning and averaged free-breathing SSFP acquisition and reconstruction times were shorter than breath-held SSFP techniques (p < 0.0001). On average, motion corrected re-binning required 3 min less than breath-held SSFP imaging, a 37% reduction in acquisition and reconstruction time. The motion corrected re-binning image reconstruction technique provides robust cardiac imaging that can be used for quantification that compares favorably to breath-held SSFP as well as multiple average free-breathing SSFP, but can be obtained in a fraction of the time when using cloud-based distributed computing reconstruction.

Sci—Thur AM: YIS - 01: Dosimetric Analysis of Respiratory Induced Cardiac Intrafraction Motion in Left-sided Breast Cancer Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

El-Sherif, O; Xhaferllari, I; Patrick, J

2014-08-15

Introduction: Long-term cardiac side effects in left-sided breast cancer patients (BREL) after post-operative radiotherapy has become one of the most debated issues in radiation oncology. Through breathing-adapted radiotherapy the volume of the heart exposed to radiation can be significantly reduced by delivering the radiation only at the end of inspiration phase of the respiratory cycle, this is referred to as inspiration gating (IG). The purpose of this study is to quantify the potential reduction in cardiac exposure during IG compared to conventional BREL radiotherapy and to assess the dosimetric impact of cardiac motion due to natural breathing. Methods: 24 BRELmore » patients treated with tangential parallel opposed photon beams were included in this study. All patients received a standard fast helical planning CT (FH-CT) and a 4D-CT. Treatment plans were created on the FH-CT using a clinical treatment planning system. The original treatment plan was then superimposed onto the end of inspiration CT and all 10 phases of the 4D-CT to quantify the dosimetric impact of respiratory motion and IG through 4D dose accumulation. Results: Through IG the mean dose to the heart, left ventricle, and left anterior descending artery (LAD) can be reduced in comparison to the clinical standard BREL treatment by as much as 8.39%, 10.11%, and 13.71% respectively (p < 0.05). Conclusion: Failure to account for respiratory motion can lead to under or overestimation in the calculated DVH for the heart, and it's sub-structures. IG can reduce cardiac exposure especially to the LAD during BREL radiotherapy.« less

The effect of heart motion on parameter bias in dynamic cardiac SPECT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ross, S.G.; Gullberg, G.T.; Huesman, R.H.

1996-12-31

Dynamic cardiac SPECT can be used to estimate kinetic rate parameters which describe the wash-in and wash-out of tracer activity between the blood and the myocardial tissue. These kinetic parameters can in turn be correlated to myocardial perfusion. There are, however, many physical aspects associated with dynamic SPECT which can introduce errors into the estimates. This paper describes a study which investigates the effect of heart motion on kinetic parameter estimates. Dynamic SPECT simulations are performed using a beating version of the MCAT phantom. The results demonstrate that cardiac motion has a significant effect on the blood, tissue, and backgroundmore » content of regions of interest. This in turn affects estimates of wash-in, while it has very little effect on estimates of wash-out. The effect of cardiac motion on parameter estimates appears not to be as great as effects introduced by photon noise and geometric collimator response. It is also shown that cardiac motion results in little extravascular contamination of the left ventricle blood region of interest.« less

Improved virtual cardiac phantom with variable diastolic filling rates and coronary artery velocities

NASA Astrophysics Data System (ADS)

Sturgeon, Gregory M.; Richards, Taylor W.; Samei, E.; Segars, W. P.

2017-03-01

To facilitate studies of measurement uncertainty in computed tomography angiography (CTA), we investigated the cardiac motion profile and resulting coronary artery motion utilizing innovative dynamic virtual and physical phantoms. The four-chamber cardiac finite element (FE) model developed in the Living Heart Project (LHP) served as the computational basis for our virtual cardiac phantom. This model provides deformation or strain information at high temporal and spatial resolution, exceeding that of speckle tracking echocardiography or tagged MRI. This model was extended by fitting its motion profile to left ventricular (LV) volume-time curves obtained from patient echocardiography data. By combining the dynamic patient variability from echo with the local strain information from the FE model, a series of virtual 4D cardiac phantoms were developed. Using the computational phantoms, we characterized the coronary motion and its effect on plaque imaging under a range of heart rates subject to variable diastolic function. The coronary artery motion was sampled at 248 spatial locations over 500 consecutive time frames. The coronary artery velocities were calculated as their average velocity during an acquisition window centered at each time frame, which minimized the discretization error. For the initial set of twelve patients, the diastatic coronary artery velocity ranged from 36.5 mm/s to 2.0 mm/s with a mean of 21.4 mm/s assuming an acquisition time of 75 ms. The developed phantoms have great potential in modeling cardiac imaging, providing a known truth and multiple realistic cardiac motion profiles to evaluate different image acquisition or reconstruction methods.

Classification of coronary artery calcifications according to motion artifacts in chest CT using a convolutional neural network

NASA Astrophysics Data System (ADS)

Šprem, Jurica; de Vos, Bob D.; de Jong, Pim A.; Viergever, Max A.; Išgum, Ivana

2017-02-01

Coronary artery calcification (CAC) is a strong and independent predictor of cardiovascular events (CVEs). CAC can be quantified in chest CT scans acquired in lung screening. However, in these images the reproducibility of CAC quantification is compromised by cardiac motion that occurs during scanning, thereby limiting the reproducibility of CVE risk assessment. We present a system for the identification of CACs strongly affected by cardiac motion artifacts by using a convolutional neural network (CNN). This study included 125 chest CT scans from the National Lung Screening Trial (NLST). Images were acquired with CT scanners from four different vendors (GE, Siemens, Philips, Toshiba) with varying tube voltage, image resolution settings, and without ECG synchronization. To define the reference standard, an observer manually identified CAC lesions and labeled each according to the presence of cardiac motion: strongly affected (positive), mildly affected/not affected (negative). A CNN was designed to automatically label the identified CAC lesions according to the presence of cardiac motion by analyzing a patch from the axial CT slice around each lesion. From 125 CT scans, 9201 CAC lesions were analyzed. 8001 lesions were used for training (19% positive) and the remaining 1200 (50% positive) were used for testing. The proposed CNN achieved a classification accuracy of 85% (86% sensitivity, 84% specificity). The obtained results demonstrate that the proposed algorithm can identify CAC lesions that are strongly affected by cardiac motion. This could facilitate further investigation into the relation of CAC scoring reproducibility and the presence of cardiac motion artifacts.

Motion estimation of magnetic resonance cardiac images using the Wigner-Ville and hough transforms

NASA Astrophysics Data System (ADS)

Carranza, N.; Cristóbal, G.; Bayerl, P.; Neumann, H.

2007-12-01

Myocardial motion analysis and quantification is of utmost importance for analyzing contractile heart abnormalities and it can be a symptom of a coronary artery disease. A fundamental problem in processing sequences of images is the computation of the optical flow, which is an approximation of the real image motion. This paper presents a new algorithm for optical flow estimation based on a spatiotemporal-frequency (STF) approach. More specifically it relies on the computation of the Wigner-Ville distribution (WVD) and the Hough Transform (HT) of the motion sequences. The latter is a well-known line and shape detection method that is highly robust against incomplete data and noise. The rationale of using the HT in this context is that it provides a value of the displacement field from the STF representation. In addition, a probabilistic approach based on Gaussian mixtures has been implemented in order to improve the accuracy of the motion detection. Experimental results in the case of synthetic sequences are compared with an implementation of the variational technique for local and global motion estimation, where it is shown that the results are accurate and robust to noise degradations. Results obtained with real cardiac magnetic resonance images are presented.

A hybrid spatiotemporal and Hough-based motion estimation approach applied to magnetic resonance cardiac images

NASA Astrophysics Data System (ADS)

Carranza, N.; Cristóbal, G.; Sroubek, F.; Ledesma-Carbayo, M. J.; Santos, A.

2006-08-01

Myocardial motion analysis and quantification is of utmost importance for analyzing contractile heart abnormalities and it can be a symptom of a coronary artery disease. A fundamental problem in processing sequences of images is the computation of the optical flow, which is an approximation to the real image motion. This paper presents a new algorithm for optical flow estimation based on a spatiotemporal-frequency (STF) approach, more specifically on the computation of the Wigner-Ville distribution (WVD) and the Hough Transform (HT) of the motion sequences. The later is a well-known line and shape detection method very robust against incomplete data and noise. The rationale of using the HT in this context is because it provides a value of the displacement field from the STF representation. In addition, a probabilistic approach based on Gaussian mixtures has been implemented in order to improve the accuracy of the motion detection. Experimental results with synthetic sequences are compared against an implementation of the variational technique for local and global motion estimation, where it is shown that the results obtained here are accurate and robust to noise degradations. Real cardiac magnetic resonance images have been tested and evaluated with the current method.

Quantification of the uncertainty in coronary CTA plaque measurements using dynamic cardiac phantom and 3D-printed plaque models

NASA Astrophysics Data System (ADS)

Richards, Taylor; Sturgeon, Gregory M.; Ramirez-Giraldo, Juan Carlos; Rubin, Geoffrey; Segars, Paul; Samei, Ehsan

2017-03-01

The purpose of this study was to quantify the accuracy of coronary computed tomography angiography (CTA) stenosis measurements using newly developed physical coronary plaque models attached to a base dynamic cardiac phantom (Shelley Medical DHP-01). Coronary plaque models (5 mm diameter, 50% stenosis, and 32 mm long) were designed and 3D-printed with tissue equivalent materials (calcified plaque with iodine enhanced lumen). Realistic cardiac motion was achieved by fitting known cardiac motion vectors to left ventricle volume-time curves to create synchronized heart motion profiles executed by the base cardiac phantom. Realistic coronary CTA acquisition was accomplished by synthesizing corresponding ECG waveforms for gating and reconstruction purposes. All scans were acquired using a retrospective gating technique on a dual-source CT system (Siemens SOMATOM FLASH) with 75ms temporal resolution. Multi-planar reformatted images were reconstructed along vessel centerlines and the enhanced lumens were manually segmented by 5 independent operators. On average, the stenosis measurement accuracy was 0.9% positive bias for the motion free condition (0 bpm). The measurement accuracy monotonically decreased to 18.5% negative bias at 90 bpm. Contrast-tonoise (CNR), vessel circularity, and segmentation conformity also decreased monotonically with increasing heart rate. These results demonstrate successful implementation of the base cardiac phantom with 3D-printed coronary plaque models, adjustable motion profiles, and coordinated ECG waveforms. They further show the utility of the model to ascertain metrics of coronary CT accuracy and image quality under a variety of plaque, motion, and acquisition conditions.

Techniques for efficient, real-time, 3D visualization of multi-modality cardiac data using consumer graphics hardware.

PubMed

Levin, David; Aladl, Usaf; Germano, Guido; Slomka, Piotr

2005-09-01

We exploit consumer graphics hardware to perform real-time processing and visualization of high-resolution, 4D cardiac data. We have implemented real-time, realistic volume rendering, interactive 4D motion segmentation of cardiac data, visualization of multi-modality cardiac data and 3D display of multiple series cardiac MRI. We show that an ATI Radeon 9700 Pro can render a 512x512x128 cardiac Computed Tomography (CT) study at 0.9 to 60 frames per second (fps) depending on rendering parameters and that 4D motion based segmentation can be performed in real-time. We conclude that real-time rendering and processing of cardiac data can be implemented on consumer graphics cards.

SU-E-T-622: Planning Technique for Passively-Scattered Involved-Node Proton Therapy of Mediastinal Lymphoma with Consideration of Cardiac Motion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flampouri, S; Li, Z; Hoppe, B

2015-06-15

Purpose: To develop a treatment planning method for passively-scattered involved-node proton therapy of mediastinal lymphoma robust to breathing and cardiac motions. Methods: Beam-specific planning treatment volumes (bsPTV) are calculated for each proton field to incorporate pertinent uncertainties. Geometric margins are added laterally to each beam while margins for range uncertainty due to setup errors, breathing, and calibration curve uncertainties are added along each beam. The calculation of breathing motion and deformation effects on proton range includes all 4DCT phases. The anisotropic water equivalent margins are translated to distances on average 4DCT. Treatment plans are designed so each beam adequately coversmore » the corresponding bsPTV. For targets close to the heart, cardiac motion effects on dosemaps are estimated by using a library of anonymous ECG-gated cardiac CTs (cCT). The cCT, originally contrast-enhanced, are partially overridden to allow meaningful proton dose calculations. Targets similar to the treatment targets are drawn on one or more cCT sets matching the anatomy of the patient. Plans based on the average cCT are calculated on individual phases, then deformed to the average and accumulated. When clinically significant dose discrepancies occur between planned and accumulated doses, the patient plan is modified to reduce the cardiac motion effects. Results: We found that bsPTVs as planning targets create dose distributions similar to the conventional proton planning distributions, while they are a valuable tool for visualization of the uncertainties. For large targets with variability in motion and depth, integral dose was reduced because of the anisotropic margins. In most cases, heart motion has a clinically insignificant effect on target coverage. Conclusion: A treatment planning method was developed and used for proton therapy of mediastinal lymphoma. The technique incorporates bsPTVs compensating for all common sources of uncertainties and estimation of the effects of cardiac motion not commonly performed.« less

Monitoring cardiac motion in CT using a continuous wave radar embedded in the patient table.

PubMed

Pfanner, Florian; Allmendinger, Thomas; Bohn, Birgit; Flohr, Thomas; Kachelrieß, Marc

2014-08-01

To avoid motion artifacts, medical imaging devices are often synchronized with the patient's cardiac motion. Today, the ECG is used to determine the heartbeat and therewith trigger the imaging device. However, the ECG requires additional effort to prepare the patient, e.g., mount and wire electrodes and it is not able to determine the motion of the heart. An interesting alternative to assess the cardiac motion is continuous wave radar. The aim of this work is to evaluate such a radar system focusing on measuring the cardiac motion. A radar system operating in the 860 MHz band is used. In the intended application of the radar system, the antennas are located close to the patient's body, for example, inside the table of a CT system. The radar waves propagate into the patient's body and are reflected at tissue boundaries, for example, at the borderline between muscle and adipose tissue, or at the boundaries of organs. Here, the authors focus on the detection of cardiac motion. The radar system consists of hardware as well as of dedicated signal processing software to extract the desired information from the radar signals. The radar system hardware and the signal processing algorithms were tested with data from ten volunteers. As a reference, the ECG was recorded simultaneously with the radar measurements. Additionally, ultrasound measurements are performed and compared with the motion information from the radar data. According to the authors' measurements on volunteers (test persons), the heartbeat and heart rate can be detected well using the proposed radar system. The authors were further able to extract the amplitude and phase of the heart motion itself from the radar data. This was confirmed by the ultrasound measurements. However, this motion assessment is dependent on the antenna position and it remains unclear which antenna sees the motion that is the most relevant to CT imaging. A continuous wave radar operating in the near field of the antennas can be used to determine the heartbeat and the cardiac motion of humans without special patient preparation. The authors' radar system is very close to the patient because it is embedded in the patient table, but it has no direct contact to the patient or to the patient skin (as it would be necessary to acquire the ECG of the patient). Therefore, radar motion monitoring does not require special patient preparation. In contrast to other methods used today, this is a significant improvement. The authors' radar system may allow to trigger a CT scan in dependency of the cardiac phase, without requiring an ECG, and it allows to determine quiet, and thus favorable, heart phases prior to the scan start.

Prototype development of an electrical impedance based simultaneous respiratory and cardiac monitoring system for gated radiotherapy.

PubMed

Kohli, Kirpal; Liu, Jeff; Schellenberg, Devin; Karvat, Anand; Parameswaran, Ash; Grewal, Parvind; Thomas, Steven

2014-10-14

In radiotherapy, temporary translocations of the internal organs and tumor induced by respiratory and cardiac activities can undesirably lead to significantly lower radiation dose on the targeted tumor but more harmful radiation on surrounding healthy tissues. Respiratory and cardiac gated radiotherapy offers a potential solution for the treatment of tumors located in the upper thorax. The present study focuses on the design and development of simultaneous acquisition of respiratory and cardiac signal using electrical impedance technology for use in dual gated radiotherapy. An electronic circuitry was developed for monitoring the bio-impedance change due to respiratory and cardiac motions and extracting the cardiogenic ECG signal. The system was analyzed in terms of reliability of signal acquisition, time delay, and functionality in a high energy radiation environment. The resulting signal of the system developed was also compared with the output of the commercially available Real-time Position Management™ (RPM) system in both time and frequency domains. The results demonstrate that the bioimpedance-based method can potentially provide reliable tracking of respiratory and cardiac motion in humans, alternative to currently available methods. When compared with the RPM system, the impedance-based system developed in the present study shows similar output pattern but different sensitivities in monitoring different respiratory rates. The tracking of cardiac motion was more susceptible to interference from other sources than respiratory motion but also provided synchronous output compared with the ECG signal extracted. The proposed hardware-based implementation was observed to have a worst-case time delay of approximately 33 ms for respiratory monitoring and 45 ms for cardiac monitoring. No significant effect on the functionality of the system was observed when it was tested in a radiation environment with the electrode lead wires directly exposed to high-energy X-Rays. The developed system capable of rendering quality signals for tracking both respiratory and cardiac motions can potentially provide a solution for simultaneous dual-gated radiotherapy.

Development of a force-reflecting robotic platform for cardiac catheter navigation.

PubMed

Park, Jun Woo; Choi, Jaesoon; Pak, Hui-Nam; Song, Seung Joon; Lee, Jung Chan; Park, Yongdoo; Shin, Seung Min; Sun, Kyung

2010-11-01

Electrophysiological catheters are used for both diagnostics and clinical intervention. To facilitate more accurate and precise catheter navigation, robotic cardiac catheter navigation systems have been developed and commercialized. The authors have developed a novel force-reflecting robotic catheter navigation system. The system is a network-based master-slave configuration having a 3-degree of freedom robotic manipulator for operation with a conventional cardiac ablation catheter. The master manipulator implements a haptic user interface device with force feedback using a force or torque signal either measured with a sensor or estimated from the motor current signal in the slave manipulator. The slave manipulator is a robotic motion control platform on which the cardiac ablation catheter is mounted. The catheter motions-forward and backward movements, rolling, and catheter tip bending-are controlled by electromechanical actuators located in the slave manipulator. The control software runs on a real-time operating system-based workstation and implements the master/slave motion synchronization control of the robot system. The master/slave motion synchronization response was assessed with step, sinusoidal, and arbitrarily varying motion commands, and showed satisfactory performance with insignificant steady-state motion error. The current system successfully implemented the motion control function and will undergo safety and performance evaluation by means of animal experiments. Further studies on the force feedback control algorithm and on an active motion catheter with an embedded actuation mechanism are underway. © 2010, Copyright the Authors. Artificial Organs © 2010, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Reanimating patients: cardio-respiratory CT and MR motion phantoms based on clinical CT patient data

NASA Astrophysics Data System (ADS)

Mayer, Johannes; Sauppe, Sebastian; Rank, Christopher M.; Sawall, Stefan; Kachelrieß, Marc

2017-03-01

Until today several algorithms have been developed that reduce or avoid artifacts caused by cardiac and respiratory motion in computed tomography (CT). The motion information is converted into so-called motion vector fields (MVFs) and used for motion compensation (MoCo) during the image reconstruction. To analyze these algorithms quantitatively there is the need for ground truth patient data displaying realistic motion. We developed a method to generate a digital ground truth displaying realistic cardiac and respiratory motion that can be used as a tool to assess MoCo algorithms. By the use of available MoCo methods we measured the motion in CT scans with high spatial and temporal resolution and transferred the motion information onto patient data with different anatomy or imaging modality, thereby reanimating the patient virtually. In addition to these images the ground truth motion information in the form of MVFs is available and can be used to benchmark the MVF estimation of MoCo algorithms. We here applied the method to generate 20 CT volumes displaying detailed cardiac motion that can be used for cone-beam CT (CBCT) simulations and a set of 8 MR volumes displaying respiratory motion. Our method is able to reanimate patient data virtually. In combination with the MVFs it serves as a digital ground truth and provides an improved framework to assess MoCo algorithms.

Validation of cardiac accelerometer sensor measurements.

PubMed

Remme, Espen W; Hoff, Lars; Halvorsen, Per Steinar; Naerum, Edvard; Skulstad, Helge; Fleischer, Lars A; Elle, Ole Jakob; Fosse, Erik

2009-12-01

In this study we have investigated the accuracy of an accelerometer sensor designed for the measurement of cardiac motion and automatic detection of motion abnormalities caused by myocardial ischaemia. The accelerometer, attached to the left ventricular wall, changed its orientation relative to the direction of gravity during the cardiac cycle. This caused a varying gravity component in the measured acceleration signal that introduced an error in the calculation of myocardial motion. Circumferential displacement, velocity and rotation of the left ventricular apical region were calculated from the measured acceleration signal. We developed a mathematical method to separate translational and gravitational acceleration components based on a priori assumptions of myocardial motion. The accuracy of the measured motion was investigated by comparison with known motion of a robot arm programmed to move like the heart wall. The accuracy was also investigated in an animal study. The sensor measurements were compared with simultaneously recorded motion from a robot arm attached next to the sensor on the heart and with measured motion by echocardiography and a video camera. The developed compensation method for the varying gravity component improved the accuracy of the calculated velocity and displacement traces, giving very good agreement with the reference methods.

The Cardiac Atlas Project--an imaging database for computational modeling and statistical atlases of the heart.

PubMed

Fonseca, Carissa G; Backhaus, Michael; Bluemke, David A; Britten, Randall D; Chung, Jae Do; Cowan, Brett R; Dinov, Ivo D; Finn, J Paul; Hunter, Peter J; Kadish, Alan H; Lee, Daniel C; Lima, Joao A C; Medrano-Gracia, Pau; Shivkumar, Kalyanam; Suinesiaputra, Avan; Tao, Wenchao; Young, Alistair A

2011-08-15

Integrative mathematical and statistical models of cardiac anatomy and physiology can play a vital role in understanding cardiac disease phenotype and planning therapeutic strategies. However, the accuracy and predictive power of such models is dependent upon the breadth and depth of noninvasive imaging datasets. The Cardiac Atlas Project (CAP) has established a large-scale database of cardiac imaging examinations and associated clinical data in order to develop a shareable, web-accessible, structural and functional atlas of the normal and pathological heart for clinical, research and educational purposes. A goal of CAP is to facilitate collaborative statistical analysis of regional heart shape and wall motion and characterize cardiac function among and within population groups. Three main open-source software components were developed: (i) a database with web-interface; (ii) a modeling client for 3D + time visualization and parametric description of shape and motion; and (iii) open data formats for semantic characterization of models and annotations. The database was implemented using a three-tier architecture utilizing MySQL, JBoss and Dcm4chee, in compliance with the DICOM standard to provide compatibility with existing clinical networks and devices. Parts of Dcm4chee were extended to access image specific attributes as search parameters. To date, approximately 3000 de-identified cardiac imaging examinations are available in the database. All software components developed by the CAP are open source and are freely available under the Mozilla Public License Version 1.1 (http://www.mozilla.org/MPL/MPL-1.1.txt). http://www.cardiacatlas.org a.young@auckland.ac.nz Supplementary data are available at Bioinformatics online.

TU-F-BRF-07: Accuracy of Routine Treatment Planning 4D and DIBH CT Delineation of the Left Anterior Descending Artery in Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, B; Lin, L; Freedmen, G

2014-06-15

Purpose: To assess the feasibility of routine treatment planning 4DCT and deep inspiration breath-hold (DIBH) to accurately contour the left anterior descending artery (LAD), a primary indicator of cardiac toxicity, for radiotherapy treatment planning of breast cancer. Methods: Ten subjects were imaged with a cardiac-gated MRI protocol to determine the displacement of a ROI that included the LAD. The subjects performed a series of breath-hold maneuvers to obtain short-axis and radial views, which were resampled to create a 3D-volume. Tissue motion was determined using a multi-resolution 3D optical flow deformable image registration algorithm. The ROI motion was then used asmore » a spatial boundary to characterize the blurring motion of the LAD in ten patients during clinical 4DCT and DIBH protocols. A radiologist contoured the LAD. Coronary motion-induced blurring artifacts were quantified by applying an unsharp filter to accentuate the LAD despite motion-blurring. The 4DCT maximum inhalation and exhalation respiratory phases were co-registered to determine the LAD displacement during tidal respiration, as visualized in 4DCT. Results: The average 90{sup th} percentile heart motion for the ROI was 0.7±0.1mm(LR), 1.3±0.6mm(SI), 0.6±0.2mm(AP) in the cardiac-gated MRI cohort. The average relative increase in the number of voxels comprising the LAD contour was 69.4±4.5% for the DIBH. During tidal respiration, the average relative increase in the LAD contour was 69.3±5.9% and 67.9±4.6% for inhalation and exhalation respiratory phases respectively. The average 90{sup th} percentile LAD motion was 4.8±1.1mm(LR), 0.9±0.4mm(SI), 1.9±0.6mm(AP) for the 4DCT cohort, in the absence of cardiac-gating. Conclusion: Uncompensated coronary motion was the dominant form of motion blurring present in the CT images due to the high frequency of the cardiac cycle relative to the respiratory cycle. The 4D and DIBH CT contour delineation of the LAD was consistently overestimated without cardiac-gating, which could have led to inaccurate dose volume histogram indicators in clinical practice.« less

Electrocardiographically gated 16-section CT of the thorax: cardiac motion suppression.

PubMed

Hofmann, Lars K; Zou, Kelly H; Costello, Philip; Schoepf, U Joseph

2004-12-01

Thirty patients underwent 16-section multi-detector row computed tomographic (CT) angiography of the thorax with retrospective electrocardiographic gating. Institutional review board approval was obtained for retrospective analysis of CT scan data and records; patient informed consent was not required. Images reconstructed at six different time points (0%, 20%, 40%, 50%, 60%, 80%) within the R-R interval on the electrocardiogram were analyzed by two radiologists for diagnostic quality, to identify suitable reconstruction intervals for optimal suppression of cardiac motion. Five regions of interest (left coronary artery, aortic root, ascending and descending aorta, pulmonary arteries) were evaluated. Best image quality was achieved by referencing image reconstruction to middiastole (50%-60%) for the left coronary artery, aortic root, and ascending aorta. The pulmonary arteries are best displayed during mid- to late diastole (80%). (c) RSNA, 2004

Large-deflection statics analysis of active cardiac catheters through co-rotational modelling.

PubMed

Peng Qi; Chen Qiu; Mehndiratta, Aadarsh; I-Ming Chen; Haoyong Yu

2016-08-01

This paper presents a co-rotational concept for large-deflection formulation of cardiac catheters. Using this approach, the catheter is first discretized with a number of equal length beam elements and nodes, and the rigid body motions of an individual beam element are separated from its deformations. Therefore, it is adequate for modelling arbitrarily large deflections of a catheter with linear elastic analysis at the local element level. A novel design of active cardiac catheter of 9 Fr in diameter at the beginning of the paper is proposed, which is based on the contra-rotating double helix patterns and is improved from the previous prototypes. The modelling section is followed by MATLAB simulations of various deflections when the catheter is exerted different types of loads. This proves the feasibility of the presented modelling approach. To the best knowledge of the authors, it is the first to utilize this methodology for large-deflection static analysis of the catheter, which will enable more accurate control of robot-assisted cardiac catheterization procedures. Future work would include further experimental validations.

Improving best-phase image quality in cardiac CT by motion correction with MAM optimization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rohkohl, Christopher; Bruder, Herbert; Stierstorfer, Karl

2013-03-15

Purpose: Research in image reconstruction for cardiac CT aims at using motion correction algorithms to improve the image quality of the coronary arteries. The key to those algorithms is motion estimation, which is currently based on 3-D/3-D registration to align the structures of interest in images acquired in multiple heart phases. The need for an extended scan data range covering several heart phases is critical in terms of radiation dose to the patient and limits the clinical potential of the method. Furthermore, literature reports only slight quality improvements of the motion corrected images when compared to the most quiet phasemore » (best-phase) that was actually used for motion estimation. In this paper a motion estimation algorithm is proposed which does not require an extended scan range but works with a short scan data interval, and which markedly improves the best-phase image quality. Methods: Motion estimation is based on the definition of motion artifact metrics (MAM) to quantify motion artifacts in a 3-D reconstructed image volume. The authors use two different MAMs, entropy, and positivity. By adjusting the motion field parameters, the MAM of the resulting motion-compensated reconstruction is optimized using a gradient descent procedure. In this way motion artifacts are minimized. For a fast and practical implementation, only analytical methods are used for motion estimation and compensation. Both the MAM-optimization and a 3-D/3-D registration-based motion estimation algorithm were investigated by means of a computer-simulated vessel with a cardiac motion profile. Image quality was evaluated using normalized cross-correlation (NCC) with the ground truth template and root-mean-square deviation (RMSD). Four coronary CT angiography patient cases were reconstructed to evaluate the clinical performance of the proposed method. Results: For the MAM-approach, the best-phase image quality could be improved for all investigated heart phases, with a maximum improvement of the NCC value by 100% and of the RMSD value by 81%. The corresponding maximum improvements for the registration-based approach were 20% and 40%. In phases with very rapid motion the registration-based algorithm obtained better image quality, while the image quality of the MAM algorithm was superior in phases with less motion. The image quality improvement of the MAM optimization was visually confirmed for the different clinical cases. Conclusions: The proposed method allows a software-based best-phase image quality improvement in coronary CT angiography. A short scan data interval at the target heart phase is sufficient, no additional scan data in other cardiac phases are required. The algorithm is therefore directly applicable to any standard cardiac CT acquisition protocol.« less

TU-EF-304-04: A Heart Motion Model for Proton Scanned Beam Chest Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, B; Kiely, J Blanco; Lin, L

Purpose: To model fast-moving heart surface motion as a function of cardiac-phase in order to compensate for the lack of cardiac-gating in evaluating accurate dose to coronary structures. Methods: Ten subjects were prospectively imaged with a breath-hold, cardiac-gated MRI protocol to determine heart surface motion. Radial and planar views of the heart were resampled into a 3-dimensional volume representing one heartbeat. A multi-resolution optical flow deformable image registration algorithm determined tissue displacement during the cardiac-cycle. The surface of the heart was modeled as a thin membrane comprised of voxels perpendicular to a pencil beam scanning (PBS) beam. The membrane’s out-of-planemore » spatial displacement was modeled as a harmonic function with Lame’s equations. Model accuracy was assessed with the root mean squared error (RMSE). The model was applied to a cohort of six chest wall irradiation patients with PBS plans generated on phase-sorted 4DCT. Respiratory motion was separated from the cardiac motion with a previously published technique. Volumetric dose painting was simulated and dose accumulated to validate plan robustness (target coverage variation accepted within 2%). Maximum and mean heart surface dose assessed the dosimetric impact of heart and coronary artery motion. Results: Average and maximum heart surface displacements were 2.54±0.35mm and 3.6mm from the end-diastole phase to the end-systole cardiac-phase respectively. An average RMSE of 0.11±0.04 showed the model to be accurate. Observed errors were greatest between the circumflex artery and mitral valve level of the heart anatomy. Heart surface displacements correspond to a 3.6±1.0% and 5.1±2.3% dosimetric impact on the maximum and mean heart surface DVH indicators respectively. Conclusion: Although heart surface motion parallel to beam’s direction was substantial, its maximum dosimetric impact was 5.1±2.3%. Since PBS delivers low doses to coronary structures relative to photon radiotherapy, it is unknown whether this variation would be clinically significant for late effects.« less

Prognostic value of dobutamine stress echocardiography in patients referred because of suspected coronary artery disease.

PubMed

Kamaran, M; Teague, S M; Finkelhor, R S; Dawson, N; Bahler, R C

1995-11-01

To determine whether dobutamine stress echocardiography (DSE) provides prognostic information beyond that available from routine clinical data, we reviewed the outcome of 210 consecutive patients referred for DSE to evaluate chest pain, perioperative risk, and myocardial viability. Dobutamine was infused in increments of 10 micrograms/kg/min in 5-minute stages to a maximum of 40 micrograms/kg/min. The dobutamine stress echocardiogram was considered abnormal only if dobutamine induced a new wall motion abnormality as determined by review of the digitized echocardiographic images in a quad screen format and on videotape. Thirty percent of tests were abnormal. An abnormal test was more common (p < or = 0.02) in men and patients with angina pectoris, in patients taking nitrate therapy, or those with prior myocardial infarction or abnormal left ventricular wall motion at rest. Twenty-two deaths, 17 of which were cardiac, occurred over a median follow-up of 240 days (range 30 to 760). Sixteen cardiac deaths occurred in the 63 patients with versus 1 cardiac death among the 147 without a new wall motion abnormality (p < or = 0.0001). Other variables associated with cardiac death (p < or = 0.05) were age > 65 years, nitrate therapy, ventricular ectopy during DSE, suspected angina pectoris, and hospitalization at the time of DSE. When cardiac death, myocardial infarction, and revascularization procedures were all considered as adverse outcomes, a new wall motion abnormality continued to be the most powerful predictor of an adverse cardiac event.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac motion correction based on partial angle reconstructed images in x-ray CT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Seungeon; Chang, Yongjin; Ra, Jong Beom, E-mail: jbra@kaist.ac.kr

2015-05-15

Purpose: Cardiac x-ray CT imaging is still challenging due to heart motion, which cannot be ignored even with the current rotation speed of the equipment. In response, many algorithms have been developed to compensate remaining motion artifacts by estimating the motion using projection data or reconstructed images. In these algorithms, accurate motion estimation is critical to the compensated image quality. In addition, since the scan range is directly related to the radiation dose, it is preferable to minimize the scan range in motion estimation. In this paper, the authors propose a novel motion estimation and compensation algorithm using a sinogrammore » with a rotation angle of less than 360°. The algorithm estimates the motion of the whole heart area using two opposite 3D partial angle reconstructed (PAR) images and compensates the motion in the reconstruction process. Methods: A CT system scans the thoracic area including the heart over an angular range of 180° + α + β, where α and β denote the detector fan angle and an additional partial angle, respectively. The obtained cone-beam projection data are converted into cone-parallel geometry via row-wise fan-to-parallel rebinning. Two conjugate 3D PAR images, whose center projection angles are separated by 180°, are then reconstructed with an angular range of β, which is considerably smaller than a short scan range of 180° + α. Although these images include limited view angle artifacts that disturb accurate motion estimation, they have considerably better temporal resolution than a short scan image. Hence, after preprocessing these artifacts, the authors estimate a motion model during a half rotation for a whole field of view via nonrigid registration between the images. Finally, motion-compensated image reconstruction is performed at a target phase by incorporating the estimated motion model. The target phase is selected as that corresponding to a view angle that is orthogonal to the center view angles of two conjugate PAR images. To evaluate the proposed algorithm, digital XCAT and physical dynamic cardiac phantom datasets are used. The XCAT phantom datasets were generated with heart rates of 70 and 100 bpm, respectively, by assuming a system rotation time of 300 ms. A physical dynamic cardiac phantom was scanned using a slowly rotating XCT system so that the effective heart rate will be 70 bpm for a system rotation speed of 300 ms. Results: In the XCAT phantom experiment, motion-compensated 3D images obtained from the proposed algorithm show coronary arteries with fewer motion artifacts for all phases. Moreover, object boundaries contaminated by motion are well restored. Even though object positions and boundary shapes are still somewhat different from the ground truth in some cases, the authors see that visibilities of coronary arteries are improved noticeably and motion artifacts are reduced considerably. The physical phantom study also shows that the visual quality of motion-compensated images is greatly improved. Conclusions: The authors propose a novel PAR image-based cardiac motion estimation and compensation algorithm. The algorithm requires an angular scan range of less than 360°. The excellent performance of the proposed algorithm is illustrated by using digital XCAT and physical dynamic cardiac phantom datasets.« less

Motion-compensated compressed sensing for dynamic contrast-enhanced MRI using regional spatiotemporal sparsity and region tracking: Block LOw-rank Sparsity with Motion-guidance (BLOSM)

PubMed Central

Chen, Xiao; Salerno, Michael; Yang, Yang; Epstein, Frederick H.

2014-01-01

Purpose Dynamic contrast-enhanced MRI of the heart is well-suited for acceleration with compressed sensing (CS) due to its spatiotemporal sparsity; however, respiratory motion can degrade sparsity and lead to image artifacts. We sought to develop a motion-compensated CS method for this application. Methods A new method, Block LOw-rank Sparsity with Motion-guidance (BLOSM), was developed to accelerate first-pass cardiac MRI, even in the presence of respiratory motion. This method divides the images into regions, tracks the regions through time, and applies matrix low-rank sparsity to the tracked regions. BLOSM was evaluated using computer simulations and first-pass cardiac datasets from human subjects. Using rate-4 acceleration, BLOSM was compared to other CS methods such as k-t SLR that employs matrix low-rank sparsity applied to the whole image dataset, with and without motion tracking, and to k-t FOCUSS with motion estimation and compensation that employs spatial and temporal-frequency sparsity. Results BLOSM was qualitatively shown to reduce respiratory artifact compared to other methods. Quantitatively, using root mean squared error and the structural similarity index, BLOSM was superior to other methods. Conclusion BLOSM, which exploits regional low rank structure and uses region tracking for motion compensation, provides improved image quality for CS-accelerated first-pass cardiac MRI. PMID:24243528

Simultaneous Assessment of Myocardial Perfusion, Wall Motion, and Deformation during Myocardial Contrast Echocardiography: A Feasibility Study.

PubMed

Zoppellaro, Giacomo; Venneri, Lucia; Khattar, Rajdeep S; Li, Wei; Senior, Roxy

2016-06-01

Ultrasound contrast agents may be used for the assessment of regional wall motion and myocardial perfusion, but are generally considered not suitable for deformation analysis. The aim of our study was to assess the feasibility of deformation imaging on contrast-enhanced images using a novel methodology. We prospectively enrolled 40 patients who underwent stress echocardiography with continuous intravenous infusion of SonoVue for the assessment of myocardial perfusion imaging with flash replenishment technique. We compared longitudinal strain (Lε) values, assessed with a vendor-independent software (2D CPA), on 68 resting contrast-enhanced and 68 resting noncontrast recordings. Strain analysis on contrast recordings was evaluated in the first cardiac cycles after the flash. Tracking of contrast images was deemed feasible in all subjects and in all views. Contrast administration improved image quality and increased the number of segments used for deformation analysis. Lε of noncontrast and contrast-enhanced images were statistically different (-18.8 ± 4.5% and -22.8 ± 5.4%, respectively; P < 0.001), but their correlation was good (ICC 0.65, 95%CI 0.42-0.78). Patients with resting wall-motion abnormalities showed lower Lε values on contrast recordings (-18.6 ± 6.0% vs. -24.2 ± 5.5%, respectively; P < 0.01). Intra-operator and inter-operator reproducibility was good for both noncontrast and contrast images with no statistical differences. Our study shows that deformation analysis on postflash contrast-enhanced images is feasible and reproducible. Therefore, it would be possible to perform a simultaneous evaluation of wall-motion abnormalities, volumes, ejection fraction, perfusion defects, and cardiac deformation on the same contrast recording. © 2016, Wiley Periodicals, Inc.

Dual respiratory and cardiac motion estimation in PET imaging: Methods design and quantitative evaluation.

PubMed

Feng, Tao; Wang, Jizhe; Tsui, Benjamin M W

2018-04-01

The goal of this study was to develop and evaluate four post-reconstruction respiratory and cardiac (R&C) motion vector field (MVF) estimation methods for cardiac 4D PET data. In Method 1, the dual R&C motions were estimated directly from the dual R&C gated images. In Method 2, respiratory motion (RM) and cardiac motion (CM) were separately estimated from the respiratory gated only and cardiac gated only images. The effects of RM on CM estimation were modeled in Method 3 by applying an image-based RM correction on the cardiac gated images before CM estimation, the effects of CM on RM estimation were neglected. Method 4 iteratively models the mutual effects of RM and CM during dual R&C motion estimations. Realistic simulation data were generated for quantitative evaluation of four methods. Almost noise-free PET projection data were generated from the 4D XCAT phantom with realistic R&C MVF using Monte Carlo simulation. Poisson noise was added to the scaled projection data to generate additional datasets of two more different noise levels. All the projection data were reconstructed using a 4D image reconstruction method to obtain dual R&C gated images. The four dual R&C MVF estimation methods were applied to the dual R&C gated images and the accuracy of motion estimation was quantitatively evaluated using the root mean square error (RMSE) of the estimated MVFs. Results show that among the four estimation methods, Methods 2 performed the worst for noise-free case while Method 1 performed the worst for noisy cases in terms of quantitative accuracy of the estimated MVF. Methods 4 and 3 showed comparable results and achieved RMSE lower by up to 35% than that in Method 1 for noisy cases. In conclusion, we have developed and evaluated 4 different post-reconstruction R&C MVF estimation methods for use in 4D PET imaging. Comparison of the performance of four methods on simulated data indicates separate R&C estimation with modeling of RM before CM estimation (Method 3) to be the best option for accurate estimation of dual R&C motion in clinical situation. © 2018 American Association of Physicists in Medicine.

Comparison of left anterior descending coronary artery hemodynamics before and after angioplasty.

PubMed

Ramaswamy, S D; Vigmostad, S C; Wahle, A; Lai, Y G; Olszewski, M E; Braddy, K C; Brennan, T M H; Rossen, J D; Sonka, M; Chandran, K B

2006-02-01

Coronary artery disease (CAD) is characterized by the progression of atherosclerosis, a complex pathological process involving the initiation, deposition, development, and breakdown of the plaque. The blood flow mechanics in arteries play a critical role in the targeted locations and progression of atherosclerotic plaque. In coronary arteries with motion during the cardiac contraction and relaxation, the hemodynamic flow field is substantially different from the other arterial sites with predilection of atherosclerosis. In this study, our efforts focused on the effects of arterial motion and local geometry on the hemodynamics of a left anterior descending (LAD) coronary artery before and after clinical intervention to treat the disease. Three-dimensional (3D) arterial segments were reconstructed at 10 phases of the cardiac cycle for both pre- and postintervention based on the fusion of intravascular ultrasound (IVUS) and biplane angiographic images. An arbitrary Lagrangian-Eulerian formulation was used for the computational fluid dynamic analysis. The measured arterial translation was observed to be larger during systole after intervention and more out-of-plane motion was observed before intervention, indicating substantial alterations in the cardiac contraction after angioplasty. The time averaged axial wall shear stress ranged from -0.2 to 9.5 Pa before intervention compared to -0.02 to 3.53 Pa after intervention. Substantial oscillatory shear stress was present in the preintervention flow dynamics compared to that in the postintervention case.

Test suite for image-based motion estimation of the brain and tongue

NASA Astrophysics Data System (ADS)

Ramsey, Jordan; Prince, Jerry L.; Gomez, Arnold D.

2017-03-01

Noninvasive analysis of motion has important uses as qualitative markers for organ function and to validate biomechanical computer simulations relative to experimental observations. Tagged MRI is considered the gold standard for noninvasive tissue motion estimation in the heart, and this has inspired multiple studies focusing on other organs, including the brain under mild acceleration and the tongue during speech. As with other motion estimation approaches, using tagged MRI to measure 3D motion includes several preprocessing steps that affect the quality and accuracy of estimation. Benchmarks, or test suites, are datasets of known geometries and displacements that act as tools to tune tracking parameters or to compare different motion estimation approaches. Because motion estimation was originally developed to study the heart, existing test suites focus on cardiac motion. However, many fundamental differences exist between the heart and other organs, such that parameter tuning (or other optimization) with respect to a cardiac database may not be appropriate. Therefore, the objective of this research was to design and construct motion benchmarks by adopting an "image synthesis" test suite to study brain deformation due to mild rotational accelerations, and a benchmark to model motion of the tongue during speech. To obtain a realistic representation of mechanical behavior, kinematics were obtained from finite-element (FE) models. These results were combined with an approximation of the acquisition process of tagged MRI (including tag generation, slice thickness, and inconsistent motion repetition). To demonstrate an application of the presented methodology, the effect of motion inconsistency on synthetic measurements of head- brain rotation and deformation was evaluated. The results indicated that acquisition inconsistency is roughly proportional to head rotation estimation error. Furthermore, when evaluating non-rigid deformation, the results suggest that inconsistent motion can yield "ghost" shear strains, which are a function of slice acquisition viability as opposed to a true physical deformation.

Test Suite for Image-Based Motion Estimation of the Brain and Tongue

PubMed Central

Ramsey, Jordan; Prince, Jerry L.; Gomez, Arnold D.

2017-01-01

Noninvasive analysis of motion has important uses as qualitative markers for organ function and to validate biomechanical computer simulations relative to experimental observations. Tagged MRI is considered the gold standard for noninvasive tissue motion estimation in the heart, and this has inspired multiple studies focusing on other organs, including the brain under mild acceleration and the tongue during speech. As with other motion estimation approaches, using tagged MRI to measure 3D motion includes several preprocessing steps that affect the quality and accuracy of estimation. Benchmarks, or test suites, are datasets of known geometries and displacements that act as tools to tune tracking parameters or to compare different motion estimation approaches. Because motion estimation was originally developed to study the heart, existing test suites focus on cardiac motion. However, many fundamental differences exist between the heart and other organs, such that parameter tuning (or other optimization) with respect to a cardiac database may not be appropriate. Therefore, the objective of this research was to design and construct motion benchmarks by adopting an “image synthesis” test suite to study brain deformation due to mild rotational accelerations, and a benchmark to model motion of the tongue during speech. To obtain a realistic representation of mechanical behavior, kinematics were obtained from finite-element (FE) models. These results were combined with an approximation of the acquisition process of tagged MRI (including tag generation, slice thickness, and inconsistent motion repetition). To demonstrate an application of the presented methodology, the effect of motion inconsistency on synthetic measurements of head-brain rotation and deformation was evaluated. The results indicated that acquisition inconsistency is roughly proportional to head rotation estimation error. Furthermore, when evaluating non-rigid deformation, the results suggest that inconsistent motion can yield “ghost” shear strains, which are a function of slice acquisition viability as opposed to a true physical deformation. PMID:28781414

Myocardial strain estimation from CT: towards computer-aided diagnosis on infarction identification

NASA Astrophysics Data System (ADS)

Wong, Ken C. L.; Tee, Michael; Chen, Marcus; Bluemke, David A.; Summers, Ronald M.; Yao, Jianhua

2015-03-01

Regional myocardial strains have the potential for early quantification and detection of cardiac dysfunctions. Although image modalities such as tagged and strain-encoded MRI can provide motion information of the myocardium, they are uncommon in clinical routine. In contrary, cardiac CT images are usually available, but they only provide motion information at salient features such as the cardiac boundaries. To estimate myocardial strains from a CT image sequence, we adopted a cardiac biomechanical model with hyperelastic material properties to relate the motion on the cardiac boundaries to the myocardial deformation. The frame-to-frame displacements of the cardiac boundaries are obtained using B-spline deformable image registration based on mutual information, which are enforced as boundary conditions to the biomechanical model. The system equation is solved by the finite element method to provide the dense displacement field of the myocardium, and the regional values of the three principal strains and the six strains in cylindrical coordinates are computed in terms of the American Heart Association nomenclature. To study the potential of the estimated regional strains on identifying myocardial infarction, experiments were performed on cardiac CT image sequences of ten canines with artificially induced myocardial infarctions. The leave-one-subject-out cross validations show that, by using the optimal strain magnitude thresholds computed from ROC curves, the radial strain and the first principal strain have the best performance.

Photo-consistency registration of a 4D cardiac motion model to endoscopic video for image guidance of robotic coronary artery bypass

NASA Astrophysics Data System (ADS)

Figl, Michael; Rueckert, Daniel; Edwards, Eddie

2009-02-01

The aim of the work described in this paper is registration of a 4D preoperative motion model of the heart to the video view of the patient through the intraoperative endoscope. The heart motion is cyclical and can be modelled using multiple reconstructions of cardiac gated coronary CT. We propose the use of photoconsistency between the two views through the da Vinci endoscope to align to the preoperative heart surface model from CT. The temporal alignment from the video to the CT model could in principle be obtained from the ECG signal. We propose averaging of the photoconsistency over the cardiac cycle to improve the registration compared to a single view. Though there is considerable motion of the heart, after correct temporal alignment we suggest that the remaining motion should be close to rigid. Results are presented for simulated renderings and for real video of a beating heart phantom. We found much smoother sections at the minimum when using multiple phases for the registration, furthermore convergence was found to be better when more phases are used.

Accelerometer-Based Method for Extracting Respiratory and Cardiac Gating Information for Dual Gating during Nuclear Medicine Imaging

PubMed Central

Pänkäälä, Mikko; Paasio, Ari

2014-01-01

Both respiratory and cardiac motions reduce the quality and consistency of medical imaging specifically in nuclear medicine imaging. Motion artifacts can be eliminated by gating the image acquisition based on the respiratory phase and cardiac contractions throughout the medical imaging procedure. Electrocardiography (ECG), 3-axis accelerometer, and respiration belt data were processed and analyzed from ten healthy volunteers. Seismocardiography (SCG) is a noninvasive accelerometer-based method that measures accelerations caused by respiration and myocardial movements. This study was conducted to investigate the feasibility of the accelerometer-based method in dual gating technique. The SCG provides accelerometer-derived respiratory (ADR) data and accurate information about quiescent phases within the cardiac cycle. The correct information about the status of ventricles and atria helps us to create an improved estimate for quiescent phases within a cardiac cycle. The correlation of ADR signals with the reference respiration belt was investigated using Pearson correlation. High linear correlation was observed between accelerometer-based measurement and reference measurement methods (ECG and Respiration belt). Above all, due to the simplicity of the proposed method, the technique has high potential to be applied in dual gating in clinical cardiac positron emission tomography (PET) to obtain motion-free images in the future. PMID:25120563

Real-world applications of artificial neural networks to cardiac monitoring using radar and recent theoretical developments

NASA Astrophysics Data System (ADS)

Padgett, Mary Lou; Johnson, John L.; Vemuri, V. Rao

1997-04-01

This paper focuses on use of a new image filtering technique, Pulsed Coupled Neural Network factoring to enhance both the analysis and visual interpretation of noisy sinusoidal time signals, such as those produced by LLNL's Microwave Impulse Radar motion sensor. Separation of a slower, carrier wave from faster, finer detailed signals and from scattered noise is illustrated. The resulting images clearly illustrate the changes over time of simulated heart motion patterns. Such images can potentially assist a field medic in interpretation of the extent of combat injuries. These images can also be transmitted or stored and retrieved for later analysis.

Demons versus Level-Set motion registration for coronary 18F-sodium fluoride PET.

PubMed

Rubeaux, Mathieu; Joshi, Nikhil; Dweck, Marc R; Fletcher, Alison; Motwani, Manish; Thomson, Louise E; Germano, Guido; Dey, Damini; Berman, Daniel S; Newby, David E; Slomka, Piotr J

2016-02-27

Ruptured coronary atherosclerotic plaques commonly cause acute myocardial infarction. It has been recently shown that active microcalcification in the coronary arteries, one of the features that characterizes vulnerable plaques at risk of rupture, can be imaged using cardiac gated 18 F-sodium fluoride ( 18 F-NaF) PET. We have shown in previous work that a motion correction technique applied to cardiac-gated 18 F-NaF PET images can enhance image quality and improve uptake estimates. In this study, we further investigated the applicability of different algorithms for registration of the coronary artery PET images. In particular, we aimed to compare demons vs. level-set nonlinear registration techniques applied for the correction of cardiac motion in coronary 18 F-NaF PET. To this end, fifteen patients underwent 18 F-NaF PET and prospective coronary CT angiography (CCTA). PET data were reconstructed in 10 ECG gated bins; subsequently these gated bins were registered using demons and level-set methods guided by the extracted coronary arteries from CCTA, to eliminate the effect of cardiac motion on PET images. Noise levels, target-to-background ratios (TBR) and global motion were compared to assess image quality. Compared to the reference standard of using only diastolic PET image (25% of the counts from PET acquisition), cardiac motion registration using either level-set or demons techniques almost halved image noise due to the use of counts from the full PET acquisition and increased TBR difference between 18 F-NaF positive and negative lesions. The demons method produces smoother deformation fields, exhibiting no singularities (which reflects how physically plausible the registration deformation is), as compared to the level-set method, which presents between 4 and 8% of singularities, depending on the coronary artery considered. In conclusion, the demons method produces smoother motion fields as compared to the level-set method, with a motion that is physiologically plausible. Therefore, level-set technique will likely require additional post-processing steps. On the other hand, the observed TBR increases were the highest for the level-set technique. Further investigations of the optimal registration technique of this novel coronary PET imaging technique are warranted.

Demons versus level-set motion registration for coronary 18F-sodium fluoride PET

NASA Astrophysics Data System (ADS)

Rubeaux, Mathieu; Joshi, Nikhil; Dweck, Marc R.; Fletcher, Alison; Motwani, Manish; Thomson, Louise E.; Germano, Guido; Dey, Damini; Berman, Daniel S.; Newby, David E.; Slomka, Piotr J.

2016-03-01

Ruptured coronary atherosclerotic plaques commonly cause acute myocardial infarction. It has been recently shown that active microcalcification in the coronary arteries, one of the features that characterizes vulnerable plaques at risk of rupture, can be imaged using cardiac gated 18F-sodium fluoride (18F-NaF) PET. We have shown in previous work that a motion correction technique applied to cardiac-gated 18F-NaF PET images can enhance image quality and improve uptake estimates. In this study, we further investigated the applicability of different algorithms for registration of the coronary artery PET images. In particular, we aimed to compare demons vs. level-set nonlinear registration techniques applied for the correction of cardiac motion in coronary 18F-NaF PET. To this end, fifteen patients underwent 18F-NaF PET and prospective coronary CT angiography (CCTA). PET data were reconstructed in 10 ECG gated bins; subsequently these gated bins were registered using demons and level-set methods guided by the extracted coronary arteries from CCTA, to eliminate the effect of cardiac motion on PET images. Noise levels, target-to-background ratios (TBR) and global motion were compared to assess image quality. Compared to the reference standard of using only diastolic PET image (25% of the counts from PET acquisition), cardiac motion registration using either level-set or demons techniques almost halved image noise due to the use of counts from the full PET acquisition and increased TBR difference between 18F-NaF positive and negative lesions. The demons method produces smoother deformation fields, exhibiting no singularities (which reflects how physically plausible the registration deformation is), as compared to the level-set method, which presents between 4 and 8% of singularities, depending on the coronary artery considered. In conclusion, the demons method produces smoother motion fields as compared to the level-set method, with a motion that is physiologically plausible. Therefore, level-set technique will likely require additional post-processing steps. On the other hand, the observed TBR increases were the highest for the level-set technique. Further investigations of the optimal registration technique of this novel coronary PET imaging technique are warranted.

Changes in dynamic embryonic heart wall motion in response to outflow tract banding measured using video densitometry

NASA Astrophysics Data System (ADS)

Stovall, Stephanie; Midgett, Madeline; Thornburg, Kent; Rugonyi, Sandra

2016-11-01

Abnormal blood flow during early cardiovascular development has been identified as a key factor in the pathogenesis of congenital heart disease; however, the mechanisms by which altered hemodynamics induce cardiac malformations are poorly understood. This study used outflow tract (OFT) banding to model increased afterload, pressure, and blood flow velocities at tubular stages of heart development and characterized the immediate changes in cardiac wall motion due to banding in chicken embryo models with light microscopy-based video densitometry. Optical videos were used to acquire two-dimensional heart image sequences over the cardiac cycle, from which intensity data were extracted along the heart centerline at several locations in the heart ventricle and OFT. While no changes were observed in the synchronous contraction of the ventricle with banding, the peristaltic-like wall motion in the OFT was significantly affected. Our data provide valuable insight into early cardiac biomechanics and its characterization using a simple light microscopy-based imaging modality.

Optimisation of reconstruction--reprojection-based motion correction for cardiac SPECT.

PubMed

Kangasmaa, Tuija S; Sohlberg, Antti O

2014-07-01

Cardiac motion is a challenging cause of image artefacts in myocardial perfusion SPECT. A wide range of motion correction methods have been developed over the years, and so far automatic algorithms based on the reconstruction--reprojection principle have proved to be the most effective. However, these methods have not been fully optimised in terms of their free parameters and implementational details. Two slightly different implementations of reconstruction--reprojection-based motion correction techniques were optimised for effective, good-quality motion correction and then compared with each other. The first of these methods (Method 1) was the traditional reconstruction-reprojection motion correction algorithm, where the motion correction is done in projection space, whereas the second algorithm (Method 2) performed motion correction in reconstruction space. The parameters that were optimised include the type of cost function (squared difference, normalised cross-correlation and mutual information) that was used to compare measured and reprojected projections, and the number of iterations needed. The methods were tested with motion-corrupt projection datasets, which were generated by adding three different types of motion (lateral shift, vertical shift and vertical creep) to motion-free cardiac perfusion SPECT studies. Method 2 performed slightly better overall than Method 1, but the difference between the two implementations was small. The execution time for Method 2 was much longer than for Method 1, which limits its clinical usefulness. The mutual information cost function gave clearly the best results for all three motion sets for both correction methods. Three iterations were sufficient for a good quality correction using Method 1. The traditional reconstruction--reprojection-based method with three update iterations and mutual information cost function is a good option for motion correction in clinical myocardial perfusion SPECT.

Myocardial motion estimation of tagged cardiac magnetic resonance images using tag motion constraints and multi-level b-splines interpolation.

PubMed

Liu, Hong; Yan, Meng; Song, Enmin; Wang, Jie; Wang, Qian; Jin, Renchao; Jin, Lianghai; Hung, Chih-Cheng

2016-05-01

Myocardial motion estimation of tagged cardiac magnetic resonance (TCMR) images is of great significance in clinical diagnosis and the treatment of heart disease. Currently, the harmonic phase analysis method (HARP) and the local sine-wave modeling method (SinMod) have been proven as two state-of-the-art motion estimation methods for TCMR images, since they can directly obtain the inter-frame motion displacement vector field (MDVF) with high accuracy and fast speed. By comparison, SinMod has better performance over HARP in terms of displacement detection, noise and artifacts reduction. However, the SinMod method has some drawbacks: 1) it is unable to estimate local displacements larger than half of the tag spacing; 2) it has observable errors in tracking of tag motion; and 3) the estimated MDVF usually has large local errors. To overcome these problems, we present a novel motion estimation method in this study. The proposed method tracks the motion of tags and then estimates the dense MDVF by using the interpolation. In this new method, a parameter estimation procedure for global motion is applied to match tag intersections between different frames, ensuring specific kinds of large displacements being correctly estimated. In addition, a strategy of tag motion constraints is applied to eliminate most of errors produced by inter-frame tracking of tags and the multi-level b-splines approximation algorithm is utilized, so as to enhance the local continuity and accuracy of the final MDVF. In the estimation of the motion displacement, our proposed method can obtain a more accurate MDVF compared with the SinMod method and our method can overcome the drawbacks of the SinMod method. However, the motion estimation accuracy of our method depends on the accuracy of tag lines detection and our method has a higher time complexity. Copyright © 2015 Elsevier Inc. All rights reserved.

Echocardiography as an indication of continuous-time cardiac quiescence

NASA Astrophysics Data System (ADS)

Wick, C. A.; Auffermann, W. F.; Shah, A. J.; Inan, O. T.; Bhatti, P. T.; Tridandapani, S.

2016-07-01

Cardiac computed tomography (CT) angiography using prospective gating requires that data be acquired during intervals of minimal cardiac motion to obtain diagnostic images of the coronary vessels free of motion artifacts. This work is intended to assess B-mode echocardiography as a continuous-time indication of these quiescent periods to determine if echocardiography can be used as a cost-efficient, non-ionizing modality to develop new prospective gating techniques for cardiac CT. These new prospective gating approaches will not be based on echocardiography itself but on CT-compatible modalities derived from the mechanics of the heart (e.g. seismocardiography and impedance cardiography), unlike the current standard electrocardiogram. To this end, echocardiography and retrospectively-gated CT data were obtained from ten patients with varied cardiac conditions. CT reconstructions were made throughout the cardiac cycle. Motion of the interventricular septum (IVS) was calculated from both echocardiography and CT reconstructions using correlation-based, deviation techniques. The IVS was chosen because it (1) is visible in echocardiography images, whereas the coronary vessels generally are not, and (2) has been shown to be a suitable indicator of cardiac quiescence. Quiescent phases were calculated as the minima of IVS motion and CT volumes were reconstructed for these phases. The diagnostic quality of the CT reconstructions from phases calculated from echocardiography and CT data was graded on a four-point Likert scale by a board-certified radiologist fellowship-trained in cardiothoracic radiology. Using a Wilcoxon signed-rank test, no significant difference in the diagnostic quality of the coronary vessels was found between CT volumes reconstructed from echocardiography- and CT-selected phases. Additionally, there was a correlation of 0.956 between the echocardiography- and CT-selected phases. This initial work suggests that B-mode echocardiography can be used as a tool to develop CT-compatible gating techniques based on modalities derived from cardiac mechanics rather than relying on the ECG alone.

Characterization of cardiac quiescence from retrospective cardiac computed tomography using a correlation-based phase-to-phase deviation measure

PubMed Central

Wick, Carson A.; McClellan, James H.; Arepalli, Chesnal D.; Auffermann, William F.; Henry, Travis S.; Khosa, Faisal; Coy, Adam M.; Tridandapani, Srini

2015-01-01

Purpose: Accurate knowledge of cardiac quiescence is crucial to the performance of many cardiac imaging modalities, including computed tomography coronary angiography (CTCA). To accurately quantify quiescence, a method for detecting the quiescent periods of the heart from retrospective cardiac computed tomography (CT) using a correlation-based, phase-to-phase deviation measure was developed. Methods: Retrospective cardiac CT data were obtained from 20 patients (11 male, 9 female, 33–74 yr) and the left main, left anterior descending, left circumflex, right coronary artery (RCA), and interventricular septum (IVS) were segmented for each phase using a semiautomated technique. Cardiac motion of individual coronary vessels as well as the IVS was calculated using phase-to-phase deviation. As an easily identifiable feature, the IVS was analyzed to assess how well it predicts vessel quiescence. Finally, the diagnostic quality of the reconstructed volumes from the quiescent phases determined using the deviation measure from the vessels in aggregate and the IVS was compared to that from quiescent phases calculated by the CT scanner. Three board-certified radiologists, fellowship-trained in cardiothoracic imaging, graded the diagnostic quality of the reconstructions using a Likert response format: 1 = excellent, 2 = good, 3 = adequate, 4 = nondiagnostic. Results: Systolic and diastolic quiescent periods were identified for each subject from the vessel motion calculated using the phase-to-phase deviation measure. The motion of the IVS was found to be similar to the aggregate vessel (AGG) motion. The diagnostic quality of the coronary vessels for the quiescent phases calculated from the aggregate vessel (PAGG) and IVS (PIV S) deviation signal using the proposed methods was comparable to the quiescent phases calculated by the CT scanner (PCT). The one exception was the RCA, which improved for PAGG for 18 of the 20 subjects when compared to PCT (PCT = 2.48; PAGG = 2.07, p = 0.001). Conclusions: A method for quantifying the motion of specific coronary vessels using a correlation-based, phase-to-phase deviation measure was developed and tested on 20 patients receiving cardiac CT exams. The IVS was found to be a suitable predictor of vessel quiescence. The diagnostic quality of the quiescent phases detected by the proposed methods was comparable to those calculated by the CT scanner. The ability to quantify coronary vessel quiescence from the motion of the IVS can be used to develop new CTCA gating techniques and quantify the resulting potential improvement in CTCA image quality. PMID:25652511

Characterization of cardiac quiescence from retrospective cardiac computed tomography using a correlation-based phase-to-phase deviation measure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wick, Carson A.; McClellan, James H.; Arepalli, Chesnal D.

2015-02-15

Purpose: Accurate knowledge of cardiac quiescence is crucial to the performance of many cardiac imaging modalities, including computed tomography coronary angiography (CTCA). To accurately quantify quiescence, a method for detecting the quiescent periods of the heart from retrospective cardiac computed tomography (CT) using a correlation-based, phase-to-phase deviation measure was developed. Methods: Retrospective cardiac CT data were obtained from 20 patients (11 male, 9 female, 33–74 yr) and the left main, left anterior descending, left circumflex, right coronary artery (RCA), and interventricular septum (IVS) were segmented for each phase using a semiautomated technique. Cardiac motion of individual coronary vessels as wellmore » as the IVS was calculated using phase-to-phase deviation. As an easily identifiable feature, the IVS was analyzed to assess how well it predicts vessel quiescence. Finally, the diagnostic quality of the reconstructed volumes from the quiescent phases determined using the deviation measure from the vessels in aggregate and the IVS was compared to that from quiescent phases calculated by the CT scanner. Three board-certified radiologists, fellowship-trained in cardiothoracic imaging, graded the diagnostic quality of the reconstructions using a Likert response format: 1 = excellent, 2 = good, 3 = adequate, 4 = nondiagnostic. Results: Systolic and diastolic quiescent periods were identified for each subject from the vessel motion calculated using the phase-to-phase deviation measure. The motion of the IVS was found to be similar to the aggregate vessel (AGG) motion. The diagnostic quality of the coronary vessels for the quiescent phases calculated from the aggregate vessel (P{sub AGG}) and IVS (P{sub IV} {sub S}) deviation signal using the proposed methods was comparable to the quiescent phases calculated by the CT scanner (P{sub CT}). The one exception was the RCA, which improved for P{sub AGG} for 18 of the 20 subjects when compared to P{sub CT} (P{sub CT} = 2.48; P{sub AGG} = 2.07, p = 0.001). Conclusions: A method for quantifying the motion of specific coronary vessels using a correlation-based, phase-to-phase deviation measure was developed and tested on 20 patients receiving cardiac CT exams. The IVS was found to be a suitable predictor of vessel quiescence. The diagnostic quality of the quiescent phases detected by the proposed methods was comparable to those calculated by the CT scanner. The ability to quantify coronary vessel quiescence from the motion of the IVS can be used to develop new CTCA gating techniques and quantify the resulting potential improvement in CTCA image quality.« less

High performance MRI simulations of motion on multi-GPU systems.

PubMed

Xanthis, Christos G; Venetis, Ioannis E; Aletras, Anthony H

2014-07-04

MRI physics simulators have been developed in the past for optimizing imaging protocols and for training purposes. However, these simulators have only addressed motion within a limited scope. The purpose of this study was the incorporation of realistic motion, such as cardiac motion, respiratory motion and flow, within MRI simulations in a high performance multi-GPU environment. Three different motion models were introduced in the Magnetic Resonance Imaging SIMULator (MRISIMUL) of this study: cardiac motion, respiratory motion and flow. Simulation of a simple Gradient Echo pulse sequence and a CINE pulse sequence on the corresponding anatomical model was performed. Myocardial tagging was also investigated. In pulse sequence design, software crushers were introduced to accommodate the long execution times in order to avoid spurious echoes formation. The displacement of the anatomical model isochromats was calculated within the Graphics Processing Unit (GPU) kernel for every timestep of the pulse sequence. Experiments that would allow simulation of custom anatomical and motion models were also performed. Last, simulations of motion with MRISIMUL on single-node and multi-node multi-GPU systems were examined. Gradient Echo and CINE images of the three motion models were produced and motion-related artifacts were demonstrated. The temporal evolution of the contractility of the heart was presented through the application of myocardial tagging. Better simulation performance and image quality were presented through the introduction of software crushers without the need to further increase the computational load and GPU resources. Last, MRISIMUL demonstrated an almost linear scalable performance with the increasing number of available GPU cards, in both single-node and multi-node multi-GPU computer systems. MRISIMUL is the first MR physics simulator to have implemented motion with a 3D large computational load on a single computer multi-GPU configuration. The incorporation of realistic motion models, such as cardiac motion, respiratory motion and flow may benefit the design and optimization of existing or new MR pulse sequences, protocols and algorithms, which examine motion related MR applications.

Induced apnea enhances image quality and visualization of cardiopulmonary anatomic during contrastenhanced cardiac computerized tomographic angiography in children

PubMed Central

Chakravarthy, Murali; Sunilkumar, Gubbihalli; Pargaonkar, Sumant; Hosur, Rajathadri; Harivelam, Chidananda; Kavaraganahalli, Deepak; Srinivasan, Pradeep

2015-01-01

Objective: The purpose of our study was to determine the effect of induced apnea on quality of cardiopulmonary structures during computerized tomographic (CT) angiography images in children with congenital heart diseases. Methods: Pediatric patients with congenital heart defects undergoing cardiac CT angiography at our facility in the past 3 years participated in this study. The earlier patients underwent cardiac CT angiography without induced apnea and while, later, apnea was induced in patients, which was followed by electrocardiogram gated cardiac CT angiography. General anesthesia was induced using sleep dose of intravenous propofol. After the initial check CT, on request by the radiologist, apnea was induced by the anesthesiologist by administering 1 mg/kg of intravenous suxamethonium. Soon after apnea ensued, the contrast was injected, and CT angiogram carried out. CT images in the “apnea group” were compared with those in “nonapnea group.” After the completion of the procedure, the patients were mask ventilated with 100% oxygen till the spontaneous ventilation was restored. Results: We studied 46 patients, of whom 36 with apnea and yet another 10 without. The quality of the image, visualization of structures such as cardiac wall, outflow tracts, lung field, aortopulmonary shunts, and coronary arteries were analyzed and subjected to statistical analysis (Mann–Whitney U, Fischer's exact test and Pearson's Chi-square test). In the induced apnea group, overall image quality was considered excellent in 89% (n = 33) of the studies, while in the “no apnea group,” only 30% of studies were excellent. Absent or minimal motion artifacts were seen in a majority of the studies in apnea group (94%). In the nonapnea group, the respiratory and body motion artifacts were severe in 50%, moderate in 30%, and minimal in 20%, but they were significantly lesser in the apnea group. All the studied parameters were statistically significant in the apnea group in contrast to nonapnea group (P < 0.000). Conclusion: The image quality of cardiac CT angiography greatly improves, and motion artifact significantly decreases with the use of induced apnea in pediatrics patients being evaluated for congenital heart disease. This technique poses no additional morbidity of significance. PMID:25849686

Atrioventricular junction (AVJ) motion tracking: a software tool with ITK/VTK/Qt.

PubMed

Pengdong Xiao; Shuang Leng; Xiaodan Zhao; Hua Zou; Ru San Tan; Wong, Philip; Liang Zhong

2016-08-01

The quantitative measurement of the Atrioventricular Junction (AVJ) motion is an important index for ventricular functions of one cardiac cycle including systole and diastole. In this paper, a software tool that can conduct AVJ motion tracking from cardiovascular magnetic resonance (CMR) images is presented by using Insight Segmentation and Registration Toolkit (ITK), The Visualization Toolkit (VTK) and Qt. The software tool is written in C++ by using Visual Studio Community 2013 integrated development environment (IDE) containing both an editor and a Microsoft complier. The software package has been successfully implemented. From the software engineering practice, it is concluded that ITK, VTK, and Qt are very handy software systems to implement automatic image analysis functions for CMR images such as quantitative measure of motion by visual tracking.

Speeding up 3D speckle tracking using PatchMatch

NASA Astrophysics Data System (ADS)

Zontak, Maria; O'Donnell, Matthew

2016-03-01

Echocardiography provides valuable information to diagnose heart dysfunction. A typical exam records several minutes of real-time cardiac images. To enable complete analysis of 3D cardiac strains, 4-D (3-D+t) echocardiography is used. This results in a huge dataset and requires effective automated analysis. Ultrasound speckle tracking is an effective method for tissue motion analysis. It involves correlation of a 3D kernel (block) around a voxel with kernels in later frames. The search region is usually confined to a local neighborhood, due to biomechanical and computational constraints. For high strains and moderate frame-rates, however, this search region will remain large, leading to a considerable computational burden. Moreover, speckle decorrelation (due to high strains) leads to errors in tracking. To solve this, spatial motion coherency between adjacent voxels should be imposed, e.g., by averaging their correlation functions.1 This requires storing correlation functions for neighboring voxels, thus increasing memory demands. In this work, we propose an efficient search using PatchMatch, 2 a powerful method to find correspondences between images. Here we adopt PatchMatch for 3D volumes and radio-frequency signals. As opposed to an exact search, PatchMatch performs random sampling of the search region and propagates successive matches among neighboring voxels. We show that: 1) Inherently smooth offset propagation in PatchMatch contributes to spatial motion coherence without any additional processing or memory demand. 2) For typical scenarios, PatchMatch is at least 20 times faster than the exact search, while maintaining comparable tracking accuracy.

Relationship between cardiac quiescent periods derived from seismocardiography and echocardiography.

PubMed

Wick, Carson A; Inan, Omer T; Bhatti, Pamela; Tridandapani, Srini

2015-08-01

The seismocardiogram (SCG) is a measure of chest wall acceleration due to cardiac motion that could potentially supplement the electrocardiogram (ECG) to more reliably predict cardiac quiescence. Accurate prediction is critical for modalities requiring minimal motion during imaging data acquisition, such as cardiac computed tomography (CT) and magnetic resonance imaging (MRI). For seven healthy subjects, SCG and B-mode echocardiography were used to identify quiescent periods on a beat-by-beat basis. Quiescent periods were detected as time intervals when the magnitude of the velocity signals calculated from SCG and echocardiography were less than a specified threshold. The quiescent periods detected from SCG were compared to those detected from B-mode echocardiography. The quiescent periods of the SCG were found to occur before those detected by echocardiography. A linear relationship between the delay from SCG- to echocardiography-detected phases with respect to heart rate was found. This delay could potentially be used to predict cardiac quiescence from SCG-observed quiescence for use with cardiac imaging modalities such as CT and MRI.

Non-model-based correction of respiratory motion using beat-to-beat 3D spiral fat-selective imaging.

PubMed

Keegan, Jennifer; Gatehouse, Peter D; Yang, Guang-Zhong; Firmin, David N

2007-09-01

To demonstrate the feasibility of retrospective beat-to-beat correction of respiratory motion, without the need for a respiratory motion model. A high-resolution three-dimensional (3D) spiral black-blood scan of the right coronary artery (RCA) of six healthy volunteers was acquired over 160 cardiac cycles without respiratory gating. One spiral interleaf was acquired per cardiac cycle, prior to each of which a complete low-resolution fat-selective 3D spiral dataset was acquired. The respiratory motion (3D translation) on each cardiac cycle was determined by cross-correlating a region of interest (ROI) in the fat around the artery in the low-resolution datasets with that on a reference end-expiratory dataset. The measured translations were used to correct the raw data of the high-resolution spiral interleaves. Beat-to-beat correction provided consistently good results, with the image quality being better than that obtained with a fixed superior-inferior tracking factor of 0.6 and better than (N = 5) or equal to (N = 1) that achieved using a subject-specific retrospective 3D translation motion model. Non-model-based correction of respiratory motion using 3D spiral fat-selective imaging is feasible, and in this small group of volunteers produced better-quality images than a subject-specific retrospective 3D translation motion model. (c) 2007 Wiley-Liss, Inc.

A Five-Dimensional Mathematical Model for Regional and Global Changes in Cardiac Uptake and Motion

NASA Astrophysics Data System (ADS)

Pretorius, P. H.; King, M. A.; Gifford, H. C.

2004-10-01

The objective of this work was to simultaneously introduce known regional changes in contraction pattern and perfusion to the existing gated Mathematical Cardiac Torso (MCAT) phantom heart model. We derived a simple integral to calculate the fraction of the ellipsoidal volume that makes up the left ventricle (LV), taking into account the stationary apex and the moving base. After calculating the LV myocardium volume of the existing beating heart model, we employed the property of conservation of mass to manipulate the LV ejection fraction to values ranging between 13.5% and 68.9%. Multiple dynamic heart models that differ in degree of LV wall thickening, base-to-apex motion, and ejection fraction, are thus available for use with the existing MCAT methodology. To introduce more complex regional LV contraction and perfusion patterns, we used composites of dynamic heart models to create a central region with little or no motion or perfusion, surrounded by a region in which the motion and perfusion gradually reverts to normal. To illustrate this methodology, the following gated cardiac acquisitions for different clinical situations were simulated analytically: 1) reduced regional motion and perfusion; 2) same perfusion as in (1) without motion intervention; and 3) washout from the normal and diseased myocardial regions. Both motion and perfusion can change dynamically during a single rotation or multiple rotations of a simulated single-photon emission computed tomography acquisition system.

Gravity Compensation Method for Combined Accelerometer and Gyro Sensors Used in Cardiac Motion Measurements.

PubMed

Krogh, Magnus Reinsfelt; Nghiem, Giang M; Halvorsen, Per Steinar; Elle, Ole Jakob; Grymyr, Ole-Johannes; Hoff, Lars; Remme, Espen W

2017-05-01

A miniaturized accelerometer fixed to the heart can be used for monitoring of cardiac function. However, an accelerometer cannot differentiate between acceleration caused by motion and acceleration due to gravity. The accuracy of motion measurements is therefore dependent on how well the gravity component can be estimated and filtered from the measured signal. In this study we propose a new method for estimating the gravity, based on strapdown inertial navigation, using a combined accelerometer and gyro. The gyro was used to estimate the orientation of the gravity field and thereby remove it. We compared this method with two previously proposed gravity filtering methods in three experimental models using: (1) in silico computer simulated heart motion; (2) robot mimicked heart motion; and (3) in vivo measured motion on the heart in an animal model. The new method correlated excellently with the reference (r 2  > 0.93) and had a deviation from reference peak systolic displacement (6.3 ± 3.9 mm) below 0.2 ± 0.5 mm for the robot experiment model. The new method performed significantly better than the two previously proposed methods (p < 0.001). The results show that the proposed method using gyro can measure cardiac motion with high accuracy and performs better than existing methods for filtering the gravity component from the accelerometer signal.

Simulation of the Beating Heart Based on Physically Modeling aDeformable Balloon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rohmer, Damien; Sitek, Arkadiusz; Gullberg, Grant T.

2006-07-18

The motion of the beating heart is complex and createsartifacts in SPECT and x-ray CT images. Phantoms such as the JaszczakDynamic Cardiac Phantom are used to simulate cardiac motion forevaluationof acquisition and data processing protocols used for cardiacimaging. Two concentric elastic membranes filled with water are connectedto tubing and pump apparatus for creating fluid flow in and out of theinner volume to simulate motion of the heart. In the present report, themovement of two concentric balloons is solved numerically in order tocreate a computer simulation of the motion of the moving membranes in theJaszczak Dynamic Cardiac Phantom. A system ofmore » differential equations,based on the physical properties, determine the motion. Two methods aretested for solving the system of differential equations. The results ofboth methods are similar providing a final shape that does not convergeto a trivial circular profile. Finally,a tomographic imaging simulationis performed by acquiring static projections of the moving shape andreconstructing the result to observe motion artifacts. Two cases aretaken into account: in one case each projection angle is sampled for ashort time interval and the other case is sampled for a longer timeinterval. The longer sampling acquisition shows a clear improvement indecreasing the tomographic streaking artifacts.« less

Free-breathing imaging of the heart using 2D cine-GRICS (generalized reconstruction by inversion of coupled systems) with assessment of ventricular volumes and function.

PubMed

Vuissoz, Pierre-André; Odille, Freddy; Fernandez, Brice; Lohezic, Maelene; Benhadid, Adnane; Mandry, Damien; Felblinger, Jacques

2012-02-01

To assess cardiac function by means of a novel free-breathing cardiac magnetic resonance imaging (MRI) strategy. A stack of ungated 2D steady-state free precession (SSFP) slices was acquired during free breathing and reconstructed as cardiac cine imaging based on the generalized reconstruction by inversion of coupled systems (GRICS). A motion-compensated sliding window approach allows reconstructing cine movies with most motion artifacts cancelled. The proposed reconstruction uses prior knowledge from respiratory belts and electrocardiogram recordings and features a piecewise linear model that relates the electrocardiogram signal to cardiac displacements. The free-breathing protocol was validated in six subjects against a standard breath-held protocol. Image sharpness, as assessed by the image gradient entropy, was comparable to that of breath-held images and significantly better than in uncorrected images. Volumetric parameters of cardiac function in the left ventricle (LV) and right ventricle (RV) were similar, including end-systolic volumes, end-diastolic volumes and mass, stroke volumes, and ejection fractions (with differences of 3% ± 2.4 in the LV and 2.9% ± 4.4 in the RV). The duration of the free-breathing protocol was nearly the same as the breath-held protocol. Free-breathing cine-GRICS enables accurate assessment of volumetric parameters of cardiac function with efficient correction of motion. Copyright © 2011 Wiley Periodicals, Inc.

Motion-aware stroke volume quantification in 4D PC-MRI data of the human aorta.

PubMed

Köhler, Benjamin; Preim, Uta; Grothoff, Matthias; Gutberlet, Matthias; Fischbach, Katharina; Preim, Bernhard

2016-02-01

4D PC-MRI enables the noninvasive measurement of time-resolved, three-dimensional blood flow data that allow quantification of the hemodynamics. Stroke volumes are essential to assess the cardiac function and evolution of different cardiovascular diseases. The calculation depends on the wall position and vessel orientation, which both change during the cardiac cycle due to the heart muscle contraction and the pumped blood. However, current systems for the quantitative 4D PC-MRI data analysis neglect the dynamic character and instead employ a static 3D vessel approximation. We quantify differences between stroke volumes in the aorta obtained with and without consideration of its dynamics. We describe a method that uses the approximating 3D segmentation to automatically initialize segmentation algorithms that require regions inside and outside the vessel for each temporal position. This enables the use of graph cuts to obtain 4D segmentations, extract vessel surfaces including centerlines for each temporal position and derive motion information. The stroke volume quantification is compared using measuring planes in static (3D) vessels, planes with fixed angulation inside dynamic vessels (this corresponds to the common 2D PC-MRI) and moving planes inside dynamic vessels. Seven datasets with different pathologies such as aneurysms and coarctations were evaluated in close collaboration with radiologists. Compared to the experts' manual stroke volume estimations, motion-aware quantification performs, on average, 1.57% better than calculations without motion consideration. The mean difference between stroke volumes obtained with the different methods is 7.82%. Automatically obtained 4D segmentations overlap by 85.75% with manually generated ones. Incorporating motion information in the stroke volume quantification yields slight but not statistically significant improvements. The presented method is feasible for the clinical routine, since computation times are low and essential parts run fully automatically. The 4D segmentations can be used for other algorithms as well. The simultaneous visualization and quantification may support the understanding and interpretation of cardiac blood flow.

A mechanical simulator of cardiac wall kinematics.

PubMed

Cutrì, Elena; Bagnoli, Paola; Marcelli, Emanuela; Biondi, Federico; Cercenelli, Laura; Costantino, Maria Laura; Plicchi, Gianni; Fumero, Roberto

2010-01-01

Aim of this study is to develop a mechanical simulator (MS) reproducing cardiac wall kinematics [i.e., radial (R), longitudinal (L) and rotational (RT) motions] to test piezoelectric gyroscopic sensors (GS) that are able to measure cardiac torsion that has proved to be a sensitive index of cardiac performance. The MS consists of three brushless motors controlled by a dedicated software either separately or simultaneously reproducing the three main cardiac wall movements (R, L, RT) obtained by implementing different physiologic or pathologic velocity profiles derived from in vivo data. GS accuracy (max % error) was experimentally tested by connecting it to the MS driven in velocity in different working conditions [i.e., cardiac period (515-1030 ms), RT angle (4-16 degrees), GS axis inclination (0-90 degrees) with respect to the cardiac rotation axis]. The MS reproduced the tested velocity profiles well. The GS showed high accuracy in measuring both physiologic and pathologic RT velocity profiles, whereas they proved insensitive to R and L motions. GS axis inclination influenced measurements; however, it was possible to correct this taking the inclination angle cosine into account. The MS proved to be a useful tool to study cardiac wall kinematics and test GS reliability with a view to in vivo application.

Evaluation of the clinical efficacy of the PeTrack motion tracking system for respiratory gating in cardiac PET imaging

NASA Astrophysics Data System (ADS)

Manwell, Spencer; Chamberland, Marc J. P.; Klein, Ran; Xu, Tong; deKemp, Robert

2017-03-01

Respiratory gating is a common technique used to compensate for patient breathing motion and decrease the prevalence of image artifacts that can impact diagnoses. In this study a new data-driven respiratory gating method (PeTrack) was compared with a conventional optical tracking system. The performance of respiratory gating of the two systems was evaluated by comparing the number of respiratory triggers, patient breathing intervals and gross heart motion as measured in the respiratory-gated image reconstructions of rubidium-82 cardiac PET scans in test and control groups consisting of 15 and 8 scans, respectively. We found evidence suggesting that PeTrack is a robust patient motion tracking system that can be used to retrospectively assess patient motion in the event of failure of the conventional optical tracking system.

Influence of cardiac motion on stent lumen visualization in third generation dual-source CT employing a pulsatile heart model.

PubMed

Petri, Nils; Gassenmaier, Tobias; Allmendinger, Thomas; Flohr, Thomas; Voelker, Wolfram; Bley, Thorsten A

2017-02-01

To detect an in-stent restenosis, an invasive coronary angiography is commonly performed. Owing to the risk associated with this procedure, a non-invasive method to detect or exclude an in-stent restenosis is desirable. The purpose of this study was to evaluate the influence of cardiac motion on stent lumen visibility in a third-generation dual-source CT scanner (SOMATOM Force; Siemens Healthcare, Forchheim, Germany), employing a pulsatile heart model (CoroSim ® ; Mecora, Aachen, Germany). 13 coronary stents with a diameter of 3.0 mm were implanted in plastic tubes filled with a contrast medium and then fixed onto the pulsatile phantom heart model. The scans were performed while the heart model mimicked the heartbeat. Coronary stents were scanned in an orientation parallel to the scanner z-axis. The evaluation of the stents was performed by employing a medium sharp convolution kernel optimized for vascular imaging. The mean visible stent lumen was reduced from 65.6 ± 5.7% for the stents at rest to 60.8 ± 4.4% for the stents in motion (p-value: <0.001). While the difference in lumen visibility between stents in motion and at rest was significant, the use of this third-generation dual-source CT scanner enabled a high stent lumen visibility under the influence of cardiac motion. Whether this translates into a clinical setting has to be evaluated in further patient studies. Advances in knowledge: The employed modern CT scanner enables a high stent lumen visibility even under the influence of cardiac motion, which is important to detect or exclude an in-stent restenosis.

Performance of Automated Software in the Assessment of Segmental Left Ventricular Function in Cardiac CT: Comparison with Cardiac Magnetic Resonance.

PubMed

Wang, Rui; Meinel, Felix G; Schoepf, U Joseph; Canstein, Christian; Spearman, James V; De Cecco, Carlo N

2015-12-01

To evaluate the accuracy, reliability and time saving potential of a novel cardiac CT (CCT)-based, automated software for the assessment of segmental left ventricular function compared to visual and manual quantitative assessment of CCT and cardiac magnetic resonance (CMR). Forty-seven patients with suspected or known coronary artery disease (CAD) were enrolled in the study. Wall thickening was calculated. Segmental LV wall motion was automatically calculated and shown as a colour-coded polar map. Processing time for each method was recorded. Mean wall thickness in both systolic and diastolic phases on polar map, CCT, and CMR was 9.2 ± 0.1 mm and 14.9 ± 0.2 mm, 8.9 ± 0.1 mm and 14.5 ± 0.1 mm, 8.3 ± 0.1 mm and 13.6 ± 0.1 mm, respectively. Mean wall thickening was 68.4 ± 1.5 %, 64.8 ± 1.4 % and 67.1 ± 1.4 %, respectively. Agreement for the assessment of LV wall motion between CCT, CMR and polar maps was good. Bland-Altman plots and ICC indicated good agreement between CCT, CMR and automated polar maps of the diastolic and systolic segmental wall thickness and thickening. The processing time using polar map was significantly decreased compared with CCT and CMR. Automated evaluation of segmental LV function with polar maps provides similar measurements to manual CCT and CMR evaluation, albeit with substantially reduced analysis time. • Cardiac computed tomography (CCT) can accurately assess segmental left ventricular wall function. • A novel automated software permits accurate and fast evaluation of wall function. • The software may improve the clinical implementation of segmental functional analysis.

WE-EF-BRA-03: Catheter- Free Ablation with External Photon Radiation: Treatment Planning, Delivery Considerations, and Correlation of Effects with Delivered Dose

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deisher, A; Anderson, S; Cusma, J

Purpose: To plan, target, and calculate delivered dose in atrioventricular node (AVN) ablation with volume-modulated arc therapy (VMAT) in an intact porcine model. Methods: Seven pigs underwent AVN irradiation, with prescription doses ranging between 25 and 55Gy in a single fraction. Cardiac CT scans were acquired at expiration. Two physicians contoured AVN targets on 10 phases, providing estimates of target motion and inter-physician variability. Treatment planning was conducted on a static phase-averaged CT. The volume designated to receive prescription dose covered the full extent of AVN cardiac motion, expanded by 4mm for setup uncertainty. Optimization limited doses to risk structuresmore » according to single-fraction tumor treatment protocols. Orthogonal kV images were used to align bony anatomy at time of treatment. Localization was further refined with respiratory-gated cone-beam CT, and range of cardiac motion was verified under fluoroscopy. Beam delivery was respiratory-gated for expiration with a mean efficiency of 60%. Deformable registration of the 10 cardiac CT phases was used to calculate actual delivered dose for comparison to electro-anatomical and visually evident lesions. Results: The mean [minimum,maximum] amplitude of AVN cardiac motion was LR 2.9 [1.7,3.9]mm, AP 6.6 [4.4,10.4]mm, and SI 5.6 [2.0,9.9]mm. Incorporating cardiac motion into the dose calculation showed the volume receiving full dose was 40–80% of the volume indicated on the static planning image, although the contoured AVN target received full dose in all animals. Initial results suggest the dimensions of the electro-anatomical lesion are correlated with the 40Gy isodose volume. Conclusion: Image-guidance techniques allow for accurate and precise delivery of VMAT for catheter-free arrhythmia ablation. An arsenal of advanced radiation planning, dose optimization, and image-guided delivery techniques was employed to assess and mitigate effects of cardiac and respiratory motion. Feasibility of delivery to the pulmonary veins and left ventricular myocardium will be investigated in future studies. D. Packer Disclosures: Abiomed, Biosense Webster, Inc., Boston Scientific Corp., CardioFocus, Inc., Johnson and Johnson, Excerpta Medica, Ortho-McNeil-Jannsen, Sanofi Aventis, CardioInsight Technologies, InfoBionic, SIEMENS, Medtronic, Inc., CardioDx, Inc., CardioInsight Technologies, FoxP2 Medica, Mediasphere Medical, Wiley-Blackwell, St. Jude Medical, Endosense, Thermedical, EP Advocate LLC, Hansen Medical, American Heart Association, EpiEP, NIH.« less

Functional video-based analysis of 3D cardiac structures generated from human embryonic stem cells.

PubMed

Nitsch, Scarlett; Braun, Florian; Ritter, Sylvia; Scholz, Michael; Schroeder, Insa S

2018-05-01

Human embryonic stem cells (hESCs) differentiated into cardiomyocytes (CM) often develop into complex 3D structures that are composed of various cardiac cell types. Conventional methods to study the electrophysiology of cardiac cells are patch clamp and microelectrode array (MEAs) analyses. However, these methods are not suitable to investigate the contractile features of 3D cardiac clusters that detach from the surface of the culture dishes during differentiation. To overcome this problem, we developed a video-based motion detection software relying on the optical flow by Farnebäck that we call cBRA (cardiac beat rate analyzer). The beating characteristics of the differentiated cardiac clusters were calculated based on the local displacement between two subsequent images. Two differentiation protocols, which profoundly differ in the morphology of cardiac clusters generated and in the expression of cardiac markers, were used and the resulting CM were characterized. Despite these differences, beat rates and beating variabilities could be reliably determined using cBRA. Likewise, stimulation of β-adrenoreceptors by isoproterenol could easily be identified in the hESC-derived CM. Since even subtle changes in the beating features are detectable, this method is suitable for high throughput cardiotoxicity screenings. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Imaging of cardiac perfusion of free-breathing small animals using dynamic phase-correlated micro-CT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sawall, Stefan; Kuntz, Jan; Socher, Michaela

Purpose:Mouse models of cardiac diseases have proven to be a valuable tool in preclinical research. The high cardiac and respiratory rates of free breathing mice prohibit conventional in vivo cardiac perfusion studies using computed tomography even if gating methods are applied. This makes a sacrification of the animals unavoidable and only allows for the application of ex vivo methods. Methods: To overcome this issue the authors propose a low dose scan protocol and an associated reconstruction algorithm that allows for in vivo imaging of cardiac perfusion and associated processes that are retrospectively synchronized to the respiratory and cardiac motion ofmore » the animal. The scan protocol consists of repetitive injections of contrast media within several consecutive scans while the ECG, respiratory motion, and timestamp of contrast injection are recorded and synchronized to the acquired projections. The iterative reconstruction algorithm employs a six-dimensional edge-preserving filter to provide low-noise, motion artifact-free images of the animal examined using the authors' low dose scan protocol. Results: The reconstructions obtained show that the complete temporal bolus evolution can be visualized and quantified in any desired combination of cardiac and respiratory phase including reperfusion phases. The proposed reconstruction method thereby keeps the administered radiation dose at a minimum and thus reduces metabolic inference to the animal allowing for longitudinal studies. Conclusions: The authors' low dose scan protocol and phase-correlated dynamic reconstruction algorithm allow for an easy and effective way to visualize phase-correlated perfusion processes in routine laboratory studies using free-breathing mice.« less

Nuclear cardiology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Penkava, R.R.

1985-05-01

Radionuclide cardiac imaging is a safe, noninvasive alternative to cardiac catheterization for observation and evaluation of cardiac wall motion and calculation of ejection fraction. Nuclide imaging offers a greater degree of sensitivity and specificity in detecting myocardial ischemia and infarction than do conventional electrocardiographic and cardiac enzyme studies. It is especially useful in problem cases. Myocardial infarction can usually be evaluated with respect to size and relative age of infarction.

High performance MRI simulations of motion on multi-GPU systems

PubMed Central

2014-01-01

Background MRI physics simulators have been developed in the past for optimizing imaging protocols and for training purposes. However, these simulators have only addressed motion within a limited scope. The purpose of this study was the incorporation of realistic motion, such as cardiac motion, respiratory motion and flow, within MRI simulations in a high performance multi-GPU environment. Methods Three different motion models were introduced in the Magnetic Resonance Imaging SIMULator (MRISIMUL) of this study: cardiac motion, respiratory motion and flow. Simulation of a simple Gradient Echo pulse sequence and a CINE pulse sequence on the corresponding anatomical model was performed. Myocardial tagging was also investigated. In pulse sequence design, software crushers were introduced to accommodate the long execution times in order to avoid spurious echoes formation. The displacement of the anatomical model isochromats was calculated within the Graphics Processing Unit (GPU) kernel for every timestep of the pulse sequence. Experiments that would allow simulation of custom anatomical and motion models were also performed. Last, simulations of motion with MRISIMUL on single-node and multi-node multi-GPU systems were examined. Results Gradient Echo and CINE images of the three motion models were produced and motion-related artifacts were demonstrated. The temporal evolution of the contractility of the heart was presented through the application of myocardial tagging. Better simulation performance and image quality were presented through the introduction of software crushers without the need to further increase the computational load and GPU resources. Last, MRISIMUL demonstrated an almost linear scalable performance with the increasing number of available GPU cards, in both single-node and multi-node multi-GPU computer systems. Conclusions MRISIMUL is the first MR physics simulator to have implemented motion with a 3D large computational load on a single computer multi-GPU configuration. The incorporation of realistic motion models, such as cardiac motion, respiratory motion and flow may benefit the design and optimization of existing or new MR pulse sequences, protocols and algorithms, which examine motion related MR applications. PMID:24996972

Temporal Fourier analysis applied to equilibrium radionuclide cineangiography. Importance in the study of global and regional left ventricular wall motion.

PubMed

Cardot, J C; Berthout, P; Verdenet, J; Bidet, A; Faivre, R; Bassand, J P; Bidet, R; Maurat, J P

1982-01-01

Regional and global left ventricular wall motion was assessed in 120 patients using radionuclide cineangiography (RCA) and contrast angiography. Functional imaging procedures based on a temporal Fourier analysis of dynamic image sequences were applied to the study of cardiac contractility. Two images were constructed by taking the phase and amplitude values of the first harmonic in the Fourier transform for each pixel. These two images aided in determining the perimeter of the left ventricle to calculate the global ejection fraction. Regional left ventricular wall motion was studied by analyzing the phase value and by examining the distribution histogram of these values. The accuracy of global ejection fraction calculation was improved by the Fourier technique. This technique increased the sensitivity of RCA for determining segmental abnormalities especially in the left anterior oblique view (LAO).

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, Benjamin M., E-mail: benjamin.white@uphs.upenn.edu; Vennarini, Sabina; Lin, Lilie

Purpose: To assess the feasibility of radiation therapy treatment planning 4-dimensional computed tomography (4DCT) and deep-inspiration breath-hold (DIBH) CT to accurately contour the left anterior descending artery (LAD), a primary indicator of radiation-induced cardiac toxicity for patients undergoing radiation therapy. Methods and Materials: Ten subjects were prospectively imaged with a cardiac-gated MRI protocol to determine cardiac motion effects, including the displacement of a region of interest comprising the LAD. A series of planar views were obtained and resampled to create a 3-dimensional (3D) volume. A 3D optical flow deformable image registration algorithm determined tissue displacement during the cardiac cycle. Themore » measured motion was then used as a spatial boundary to characterize motion blurring of the radiologist-delineated LAD structure for a cohort of 10 consecutive patients enrolled prospectively on a breast study including 4DCT and DIBH scans. Coronary motion–induced blurring artifacts were quantified by applying an unsharp filter to accentuate the LAD structure despite the presence of motion blurring. The 4DCT maximum inhalation and exhalation respiratory phases were coregistered to determine the LAD displacement during tidal respiration, as visualized in 4DCT. Results: The average 90th percentile heart motion for the region of interest was 0.7 ± 0.1 mm (left–right [LR]), 1.3 ± 0.6 mm (superior–inferior [SI]), and 0.6 ± 0.2 mm (anterior–posterior [AP]) in the cardiac-gated MRI cohort. The average relative increase in the number of voxels comprising the LAD contour was 69.4% ± 4.5% for the DIBH. The LAD volume overestimation had the dosimetric impact of decreasing the reported mean LAD dose by 23% ± 9% on average in the DIBH. During tidal respiration the average relative LAD contour increase was 69.3% ± 5.9% and 67.9% ± 4.6% for inhalation and exhalation respiratory phases, respectively. The average 90th percentile LAD motion was 4.8 ± 1.1 mm (LR), 0.9 ± 0.4 mm (SI), and 1.9 ± 0.6 mm (AP) for the 4DCT cohort, in the absence of cardiac gating. Conclusions: An anisotropic margin of 2.7 mm (LR), 4.1 mm (SI), and 2.4 mm (AP) was quantitatively determined to account for motion blurring and patient setup error while placing minimum constraint on the plan optimization.« less

Free-breathing 3D Cardiac MRI Using Iterative Image-Based Respiratory Motion Correction

PubMed Central

Moghari, Mehdi H.; Roujol, Sébastien; Chan, Raymond H.; Hong, Susie N.; Bello, Natalie; Henningsson, Markus; Ngo, Long H.; Goddu, Beth; Goepfert, Lois; Kissinger, Kraig V.; Manning, Warren J.; Nezafat, Reza

2012-01-01

Respiratory motion compensation using diaphragmatic navigator (NAV) gating with a 5 mm gating window is conventionally used for free-breathing cardiac MRI. Due to the narrow gating window, scan efficiency is low resulting in long scan times, especially for patients with irregular breathing patterns. In this work, a new retrospective motion compensation algorithm is presented to reduce the scan time for free-breathing cardiac MRI that increasing the gating window to 15 mm without compromising image quality. The proposed algorithm iteratively corrects for respiratory-induced cardiac motion by optimizing the sharpness of the heart. To evaluate this technique, two coronary MRI datasets with 1.3 mm3 resolution were acquired from 11 healthy subjects (7 females, 25±9 years); one using a NAV with a 5 mm gating window acquired in 12.0±2.0 minutes and one with a 15 mm gating window acquired in 7.1±1.0 minutes. The images acquired with a 15 mm gating window were corrected using the proposed algorithm and compared to the uncorrected images acquired with the 5 mm and 15 mm gating windows. The image quality score, sharpness, and length of the three major coronary arteries were equivalent between the corrected images and the images acquired with a 5 mm gating window (p-value>0.05), while the scan time was reduced by a factor of 1.7. PMID:23132549

Vortical features for myocardial rotation assessment in hypertrophic cardiomyopathy using cardiac tagged magnetic resonance.

PubMed

Sanz-Estébanez, Santiago; Cordero-Grande, Lucilio; Sevilla, Teresa; Revilla-Orodea, Ana; de Luis-García, Rodrigo; Martín-Fernández, Marcos; Alberola-López, Carlos

2018-07-01

Left ventricular rotational motion is a feature of normal and diseased cardiac function. However, classical torsion and twist measures rely on the definition of a rotational axis which may not exist. This paper reviews global and local rotation descriptors of myocardial motion and introduces new curl-based (vortical) features built from tensorial magnitudes, intended to provide better comprehension about fibrotic tissue characteristics mechanical properties. Fifty-six cardiomyopathy patients and twenty-two healthy volunteers have been studied using tagged magnetic resonance by means of harmonic phase analysis. Rotation descriptors are built, with no assumption about a regular geometrical model, from different approaches. The extracted vortical features have been tested by means of a sequential cardiomyopathy classification procedure; they have proven useful for the regional characterization of the left ventricular function by showing great separability not only between pathologic and healthy patients but also, and specifically, between heterogeneous phenotypes within cardiomyopathies. Copyright © 2018 Elsevier B.V. All rights reserved.

Terminal echocardiographic findings during death process in man and dogs.

PubMed

Wang, F S; Lien, W P; Fong, T E

1991-01-01

Serial echocardiographic imaging was performed to assess terminal mechanical changes of cardiac chambers and valves, as well as sequential echocardiographic features of blood stasis, inside the heart after mechanical asystole in 7 hospitalized adults who died without apparent cardiac disease and in 7 experimental dogs sacrificed by a means of asphyxia. Marked reduction of wall motion became manifest shortly after the electrocardiograms had generated into a slow junctional rhythm with intraventricular conduction defect, an idioventricular rhythm, or an extreme sinus bradycardia. Total cessation of cardiac wall and valve motion followed; the aortic valve remained closed, with mitral and tricuspid valves semiopen after total cardiac asystole. Liquid whole blood inside the heart became echogenic shortly before mechanical asystole had approached, and homogenous echogenicity usually first appeared on the right side of the heart. As the death process progressed and total asystole persisted, the acoustic intensity of the intracavitary echoes increased, tending to form amorphous masses, with some showing rather well-defined borders. Such echocardiographic features were noted to indicate red thrombi in experimental dogs. The cardiac dimensions (left ventricle and aorta) decreased after total cardiac asystole.

Towards real-time MRI-guided 3D localization of deforming targets for non-invasive cardiac radiosurgery

NASA Astrophysics Data System (ADS)

Ipsen, S.; Blanck, O.; Lowther, N. J.; Liney, G. P.; Rai, R.; Bode, F.; Dunst, J.; Schweikard, A.; Keall, P. J.

2016-11-01

Radiosurgery to the pulmonary vein antrum in the left atrium (LA) has recently been proposed for non-invasive treatment of atrial fibrillation (AF). Precise real-time target localization during treatment is necessary due to complex respiratory and cardiac motion and high radiation doses. To determine the 3D position of the LA for motion compensation during radiosurgery, a tracking method based on orthogonal real-time MRI planes was developed for AF treatments with an MRI-guided radiotherapy system. Four healthy volunteers underwent cardiac MRI of the LA. Contractile motion was quantified on 3D LA models derived from 4D scans with 10 phases acquired in end-exhalation. Three localization strategies were developed and tested retrospectively on 2D real-time scans (sagittal, temporal resolution 100 ms, free breathing). The best-performing method was then used to measure 3D target positions in 2D-2D orthogonal planes (sagittal-coronal, temporal resolution 200-252 ms, free breathing) in 20 configurations of a digital phantom and in the volunteer data. The 3D target localization accuracy was quantified in the phantom and qualitatively assessed in the real data. Mean cardiac contraction was  ⩽  3.9 mm between maximum dilation and contraction but anisotropic. A template matching approach with two distinct template phases and ECG-based selection yielded the highest 2D accuracy of 1.2 mm. 3D target localization showed a mean error of 3.2 mm in the customized digital phantoms. Our algorithms were successfully applied to the 2D-2D volunteer data in which we measured a mean 3D LA motion extent of 16.5 mm (SI), 5.8 mm (AP) and 3.1 mm (LR). Real-time target localization on orthogonal MRI planes was successfully implemented for highly deformable targets treated in cardiac radiosurgery. The developed method measures target shifts caused by respiration and cardiac contraction. If the detected motion can be compensated accordingly, an MRI-guided radiotherapy system could potentially enable completely non-invasive treatment of AF.

Automated motion artifact removal for intravital microscopy, without a priori information.

PubMed

Lee, Sungon; Vinegoni, Claudio; Sebas, Matthew; Weissleder, Ralph

2014-03-28

Intravital fluorescence microscopy, through extended penetration depth and imaging resolution, provides the ability to image at cellular and subcellular resolution in live animals, presenting an opportunity for new insights into in vivo biology. Unfortunately, physiological induced motion components due to respiration and cardiac activity are major sources of image artifacts and impose severe limitations on the effective imaging resolution that can be ultimately achieved in vivo. Here we present a novel imaging methodology capable of automatically removing motion artifacts during intravital microscopy imaging of organs and orthotopic tumors. The method is universally applicable to different laser scanning modalities including confocal and multiphoton microscopy, and offers artifact free reconstructions independent of the physiological motion source and imaged organ. The methodology, which is based on raw data acquisition followed by image processing, is here demonstrated for both cardiac and respiratory motion compensation in mice heart, kidney, liver, pancreas and dorsal window chamber.

Automated motion artifact removal for intravital microscopy, without a priori information

PubMed Central

Lee, Sungon; Vinegoni, Claudio; Sebas, Matthew; Weissleder, Ralph

2014-01-01

Intravital fluorescence microscopy, through extended penetration depth and imaging resolution, provides the ability to image at cellular and subcellular resolution in live animals, presenting an opportunity for new insights into in vivo biology. Unfortunately, physiological induced motion components due to respiration and cardiac activity are major sources of image artifacts and impose severe limitations on the effective imaging resolution that can be ultimately achieved in vivo. Here we present a novel imaging methodology capable of automatically removing motion artifacts during intravital microscopy imaging of organs and orthotopic tumors. The method is universally applicable to different laser scanning modalities including confocal and multiphoton microscopy, and offers artifact free reconstructions independent of the physiological motion source and imaged organ. The methodology, which is based on raw data acquisition followed by image processing, is here demonstrated for both cardiac and respiratory motion compensation in mice heart, kidney, liver, pancreas and dorsal window chamber. PMID:24676021

Bard Denali inferior vena cava filter fracture and embolization resulting in cardiac tamponade: a device failure analysis.

PubMed

Kuo, William T; Robertson, Scott W

2015-01-01

A 46-year-old woman underwent inferior vena cava filter placement before bariatric surgery and returned within 6 months for routine removal. She complained of a 1-week history of severe chest pain, and during retrieval, two fractured filter components were identified including one arm in the right ventricle. The filter body and one fragment were successfully retrieved, but the fragment in the right ventricle was refractory to percutaneous retrieval. During open-heart surgery, the fragment was found traversing through the ventricular wall resulting in cardiac tamponade. Electron microscopic fragment analysis revealed high-cycle metal fatigue indicating the filter design failed to withstand this patient's natural inferior vena cava biomechanical motions. Copyright © 2015 SIR. Published by Elsevier Inc. All rights reserved.

A Real-Time Cardiac Arrhythmia Classification System with Wearable Sensor Networks

PubMed Central

Hu, Sheng; Wei, Hongxing; Chen, Youdong; Tan, Jindong

2012-01-01

Long term continuous monitoring of electrocardiogram (ECG) in a free living environment provides valuable information for prevention on the heart attack and other high risk diseases. This paper presents the design of a real-time wearable ECG monitoring system with associated cardiac arrhythmia classification algorithms. One of the striking advantages is that ECG analog front-end and on-node digital processing are designed to remove most of the noise and bias. In addition, the wearable sensor node is able to monitor the patient's ECG and motion signal in an unobstructive way. To realize the real-time medical analysis, the ECG is digitalized and transmitted to a smart phone via Bluetooth. On the smart phone, the ECG waveform is visualized and a novel layered hidden Markov model is seamlessly integrated to classify multiple cardiac arrhythmias in real time. Experimental results demonstrate that the clean and reliable ECG waveform can be captured in multiple stressed conditions and the real-time classification on cardiac arrhythmia is competent to other workbenches. PMID:23112746

New techniques for motion-artifact-free in vivo cardiac microscopy

PubMed Central

Vinegoni, Claudio; Lee, Sungon; Aguirre, Aaron D.; Weissleder, Ralph

2015-01-01

Intravital imaging microscopy (i.e., imaging in live animals at microscopic resolution) has become an indispensable tool for studying the cellular micro-dynamics in cancer, immunology and neurobiology. High spatial and temporal resolution, combined with large penetration depth and multi-reporter visualization capability make fluorescence intravital microscopy compelling for heart imaging. However, tissue motion caused by cardiac contraction and respiration critically limits its use. As a result, in vitro cell preparations or non-contracting explanted heart models are more commonly employed. Unfortunately, these approaches fall short of understanding the more complex host physiology that may be dynamic and occur over longer periods of time. In this review, we report on novel technologies, which have been recently developed by our group and others, aimed at overcoming motion-induced artifacts and capable of providing in vivo subcellular resolution imaging in the beating mouse heart. The methods are based on mechanical stabilization, image processing algorithms, gated/triggered acquisition schemes or a combination of both. We expect that in the immediate future all these methodologies will have considerable applications in expanding our understanding of the cardiac biology, elucidating cardiomyocyte function and interactions within the organism in vivo, and ultimately improving the treatment of cardiac diseases. PMID:26029116

Moving domain computational fluid dynamics to interface with an embryonic model of cardiac morphogenesis.

PubMed

Lee, Juhyun; Moghadam, Mahdi Esmaily; Kung, Ethan; Cao, Hung; Beebe, Tyler; Miller, Yury; Roman, Beth L; Lien, Ching-Ling; Chi, Neil C; Marsden, Alison L; Hsiai, Tzung K

2013-01-01

Peristaltic contraction of the embryonic heart tube produces time- and spatial-varying wall shear stress (WSS) and pressure gradients (∇P) across the atrioventricular (AV) canal. Zebrafish (Danio rerio) are a genetically tractable system to investigate cardiac morphogenesis. The use of Tg(fli1a:EGFP) (y1) transgenic embryos allowed for delineation and two-dimensional reconstruction of the endocardium. This time-varying wall motion was then prescribed in a two-dimensional moving domain computational fluid dynamics (CFD) model, providing new insights into spatial and temporal variations in WSS and ∇P during cardiac development. The CFD simulations were validated with particle image velocimetry (PIV) across the atrioventricular (AV) canal, revealing an increase in both velocities and heart rates, but a decrease in the duration of atrial systole from early to later stages. At 20-30 hours post fertilization (hpf), simulation results revealed bidirectional WSS across the AV canal in the heart tube in response to peristaltic motion of the wall. At 40-50 hpf, the tube structure undergoes cardiac looping, accompanied by a nearly 3-fold increase in WSS magnitude. At 110-120 hpf, distinct AV valve, atrium, ventricle, and bulbus arteriosus form, accompanied by incremental increases in both WSS magnitude and ∇P, but a decrease in bi-directional flow. Laminar flow develops across the AV canal at 20-30 hpf, and persists at 110-120 hpf. Reynolds numbers at the AV canal increase from 0.07±0.03 at 20-30 hpf to 0.23±0.07 at 110-120 hpf (p< 0.05, n=6), whereas Womersley numbers remain relatively unchanged from 0.11 to 0.13. Our moving domain simulations highlights hemodynamic changes in relation to cardiac morphogenesis; thereby, providing a 2-D quantitative approach to complement imaging analysis.

[Evaluation of left ventricular perfusion and regional wall motion in myocardial infarction: using 201Tl myocardial SPECT and 99mTc-HSAD multigated cardiac blood pool emission computed tomography].

PubMed

Nanjyo, S

1994-09-01

In order to evaluate left ventricular regional wall motion and regional myocardial perfusion, 99mTc-HSAD multigated cardiac blood pool emission computed tomography (cardiac pool SPECT) and 201Tl myocardial SPECT (Tl) were performed on 12 patients with acute myocardial infarction (AMI), 6 patients had treated with only thrombolysis in group I and 6 patients had treated with thrombolysis and selective PTCA in group II, 17 patients with old myocardial infarction (OMI) in group III and 5 normal volunteers (controls). The relationship between left ventricular regional wall motion and regional myocardial perfusion was estimated. The relationship between % length shortening (%LS) by cardiac pool SPECT and %Tl uptake (%TU) was good (r = 0.820) in group III. The value for %TU in the segments of akinesia was low (35%) and in the those of severe hypokinesia was higher (48%). In all phases, two groups showed significant relationships between %LS and %TU in group I and II. The %TU was unchanged in the akinetic segment, the %LS changed 30% in group I and the %LS changed to 49% in group II. If the %TU is more than 50% (AMI) or 40% (OMI), we would observe viable muscle. The combination of Tl and cardiac pool SPECT are useful for evaluating myocardial viability in the patients with AMI.

ECG-gated interventional cardiac reconstruction for non-periodic motion.

PubMed

Rohkohl, Christopher; Lauritsch, Günter; Biller, Lisa; Hornegger, Joachim

2010-01-01

The 3-D reconstruction of cardiac vasculature using C-arm CT is an active and challenging field of research. In interventional environments patients often do have arrhythmic heart signals or cannot hold breath during the complete data acquisition. This important group of patients cannot be reconstructed with current approaches that do strongly depend on a high degree of cardiac motion periodicity for working properly. In a last year's MICCAI contribution a first algorithm was presented that is able to estimate non-periodic 4-D motion patterns. However, to some degree that algorithm still depends on periodicity, as it requires a prior image which is obtained using a simple ECG-gated reconstruction. In this work we aim to provide a solution to this problem by developing a motion compensated ECG-gating algorithm. It is built upon a 4-D time-continuous affine motion model which is capable of compactly describing highly non-periodic motion patterns. A stochastic optimization scheme is derived which minimizes the error between the measured projection data and the forward projection of the motion compensated reconstruction. For evaluation, the algorithm is applied to 5 datasets of the left coronary arteries of patients that have ignored the breath hold command and/or had arrhythmic heart signals during the data acquisition. By applying the developed algorithm the average visibility of the vessel segments could be increased by 27%. The results show that the proposed algorithm provides excellent reconstruction quality in cases where classical approaches fail. The algorithm is highly parallelizable and a clinically feasible runtime of under 4 minutes is achieved using modern graphics card hardware.

Prognostic value of cardiac power output to left ventricular mass in patients with left ventricular dysfunction and dobutamine stress echo negative by wall motion criteria.

PubMed

Cortigiani, Lauro; Sorbo, Simone; Miccoli, Mario; Scali, Maria Chiara; Simioniuc, Anca; Morrone, Doralisa; Bovenzi, Francesco; Marzilli, Mario; Dini, Frank Lloyd

2017-02-01

Cardiac power output to left ventricular mass (power/mass) is an index of myocardial efficiency reflecting the rate at which cardiac work is delivered with respect to the potential energy stored in the left ventricular mass. In the present study, we sought to investigate the capability of power/mass assessed at peak of dobutamine stress echocardiography to predict mortality in patients with ischaemic cardiomyopathy and no inducible ischaemia. One-hundred eleven patients (95 males; age 68 ± 10 years) with 35 ± 7% mean left ventricular ejection fraction and a dobutamine stress echocardiography (up to 40 µg/kg/min) negative by wall motion criteria formed the study population. Power/mass at peak stress was obtained as the product of a constant (K = 2.22 × 10 -1 ) with cardiac output and the mean arterial pressure divided by left ventricular mass to convert the units to W/100 g. Patients were followed up for a median of 29 months (inter-quartile range 16-72 months). All-cause mortality was the only accepted clinical end point. Mean peak-stress power/mass was 0.70 ± 0.31 W/100 g. During follow-up, 29 deaths (26%) were registered. With a receiver operating characteristic analysis, a peak-stress power/mass ≤0.50 W/100 g [area under curve 0.72 (95% CI 0.63; 0.80), sensitivity 59%, specificity 80%] was the best value for predicting mortality. Univariate prognostic indicators were age, male sex, peak-stress ejection fraction, peak-stress stroke volume, peak-stress cardiac output, peak-stress cardiac power output ≤1.48 W, and peak-stress power/mass ≤0.50 W/100 g. At multivariate analysis, age (HR 1.08, 95% CI 1.04; 1.14; P = 0.004) and peak-stress power/mass ≤0.50 W/100 g (HR 4.05, 95% CI 1.36; 12.00; P = 0.01) provided independent prognostic information. Three-year mortality was 14% in patients with peak-stress power/mass >0.50 W/100 g and 47% in those with peak-stress power/mass ≤0.50 W/100 g (log-rank 20.4; P < 0.0001). Power/mass assessed at peak of dobutamine stress echocardiography allows effective prognostication in patients with ischaemic cardiomyopathy and test result negative by wall motion criteria. In particular, a peak-stress power/mass ≤50 W/100 g is a strong and multivariable predictor of mortality. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

Normal and Pathological NCAT Image and PhantomData Based onPhysiologically Realistic Left Ventricle Finite-Element Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Veress, Alexander I.; Segars, W. Paul; Weiss, Jeffrey A.

2006-08-02

The 4D NURBS-based Cardiac-Torso (NCAT) phantom, whichprovides a realistic model of the normal human anatomy and cardiac andrespiratory motions, is used in medical imaging research to evaluate andimprove imaging devices and techniques, especially dynamic cardiacapplications. One limitation of the phantom is that it lacks the abilityto accurately simulate altered functions of the heart that result fromcardiac pathologies such as coronary artery disease (CAD). The goal ofthis work was to enhance the 4D NCAT phantom by incorporating aphysiologically based, finite-element (FE) mechanical model of the leftventricle (LV) to simulate both normal and abnormal cardiac motions. Thegeometry of the FE mechanical modelmore » was based on gated high-resolutionx-ray multi-slice computed tomography (MSCT) data of a healthy malesubject. The myocardial wall was represented as transversely isotropichyperelastic material, with the fiber angle varying from -90 degrees atthe epicardial surface, through 0 degreesat the mid-wall, to 90 degreesat the endocardial surface. A time varying elastance model was used tosimulate fiber contraction, and physiological intraventricular systolicpressure-time curves were applied to simulate the cardiac motion over theentire cardiac cycle. To demonstrate the ability of the FE mechanicalmodel to accurately simulate the normal cardiac motion as well abnormalmotions indicative of CAD, a normal case and two pathologic cases weresimulated and analyzed. In the first pathologic model, a subendocardialanterior ischemic region was defined. A second model was created with atransmural ischemic region defined in the same location. The FE baseddeformations were incorporated into the 4D NCAT cardiac model through thecontrol points that define the cardiac structures in the phantom whichwere set to move according to the predictions of the mechanical model. Asimulation study was performed using the FE-NCAT combination toinvestigate how the differences in contractile function between thesubendocardial and transmural infarcts manifest themselves in myocardialSPECT images. The normal FE model produced strain distributions that wereconsistent with those reported in the literature and a motion consistentwith that defined in the normal 4D NCAT beating heart model based ontagged MRI data. The addition of a subendocardial ischemic region changedthe average transmural circumferential strain from a contractile value of0.19 to a tensile value of 0.03. The addition of a transmural ischemicregion changed average circumferential strain to a value of 0.16, whichis consistent with data reported in the literature. Model resultsdemonstrated differences in contractile function between subendocardialand transmural infarcts and how these differences in function aredocumented in simulated myocardial SPECT images produced using the 4DNCAT phantom. In comparison to the original NCAT beating heart model, theFE mechanical model produced a more accurate simulation for the cardiacmotion abnormalities. Such a model, when incorporated into the 4D NCATphantom, has great potential for use in cardiac imaging research. Withits enhanced physiologically-based cardiac model, the 4D NCAT phantom canbe used to simulate realistic, predictive imaging data of a patientpopulation with varying whole-body anatomy and with varying healthy anddiseased states of the heart that will provide a known truth from whichto evaluate and improve existing and emerging 4D imaging techniques usedin the diagnosis of cardiac disease.« less

Visualization of Heart Sounds and Motion Using Multichannel Sensor

NASA Astrophysics Data System (ADS)

Nogata, Fumio; Yokota, Yasunari; Kawamura, Yoko

2010-06-01

As there are various difficulties associated with auscultation techniques, we have devised a technique for visualizing heart motion in order to assist in the understanding of heartbeat for both doctors and patients. Auscultatory sounds were first visualized using FFT and Wavelet analysis to visualize heart sounds. Next, to show global and simultaneous heart motions, a new technique for visualization was established. The visualization system consists of a 64-channel unit (63 acceleration sensors and one ECG sensor) and a signal/image analysis unit. The acceleration sensors were arranged in a square array (8×8) with a 20-mm pitch interval, which was adhered to the chest surface. The heart motion of one cycle was visualized at a sampling frequency of 3 kHz and quantization of 12 bits. The visualized results showed a typical waveform motion of the strong pressure shock due to closing tricuspid valve and mitral valve of the cardiac apex (first sound), and the closing aortic and pulmonic valve (second sound) in sequence. To overcome difficulties in auscultation, the system can be applied to the detection of heart disease and to the digital database management of the auscultation examination in medical areas.

Motion-compensated compressed sensing for dynamic imaging

NASA Astrophysics Data System (ADS)

Sundaresan, Rajagopalan; Kim, Yookyung; Nadar, Mariappan S.; Bilgin, Ali

2010-08-01

The recently introduced Compressed Sensing (CS) theory explains how sparse or compressible signals can be reconstructed from far fewer samples than what was previously believed possible. The CS theory has attracted significant attention for applications such as Magnetic Resonance Imaging (MRI) where long acquisition times have been problematic. This is especially true for dynamic MRI applications where high spatio-temporal resolution is needed. For example, in cardiac cine MRI, it is desirable to acquire the whole cardiac volume within a single breath-hold in order to avoid artifacts due to respiratory motion. Conventional MRI techniques do not allow reconstruction of high resolution image sequences from such limited amount of data. Vaswani et al. recently proposed an extension of the CS framework to problems with partially known support (i.e. sparsity pattern). In their work, the problem of recursive reconstruction of time sequences of sparse signals was considered. Under the assumption that the support of the signal changes slowly over time, they proposed using the support of the previous frame as the "known" part of the support for the current frame. While this approach works well for image sequences with little or no motion, motion causes significant change in support between adjacent frames. In this paper, we illustrate how motion estimation and compensation techniques can be used to reconstruct more accurate estimates of support for image sequences with substantial motion (such as cardiac MRI). Experimental results using phantoms as well as real MRI data sets illustrate the improved performance of the proposed technique.

Instant images of the human heart using a new, whole-body MR imaging system.

PubMed

Rzedzian, R R; Pykett, I L

1987-08-01

An extremely rapid MR imaging technique is described, and its use on a new 2.0-T high-speed MR system is demonstrated. This implementation permits complete filling of the two-dimensional spatial-frequency domain (k-space) within an acquisition window of 26 msec. With this acquisition window placed under the spin-echo signal envelope generated by a 90-180 degree pulse pair, the image contrast is the same as that of a conventional spin-echo pulse sequence. Resultant proton images have a motion-independent voxel resolution of 0.08 cm3 and a signal-to-noise ratio for cardiac muscle of approximately 30:1 (for TE = 30 msec) with no signal averaging. The pulse sequence yields images that are chemical shift-resolved. The total proton density distribution is optionally presented with lipid and water signals displayed in two different colors. Cardiac function is observed by displaying multiple images, acquired at different times in successive cardiac periods, in a cyclic movie format. Such motion pictures are obtained within a single period of suspended respiration, thereby assuring freedom from respiratory related motion artifacts. As preliminary examples, we present MR images of the normal adult human heart that have total acquisition times of only 40 msec/image and that show the major cardiac anatomy. Frames from movie loops show contraction of cardiac chambers and left ventricular wall thickening. The extremely rapid acquisition time of this technique suggests that it may hold promise for the routine and cost-effective evaluation of cardiac anatomy and function.

Assessment of phase based dose modulation for improved dose efficiency in cardiac CT on an anthropomorphic motion phantom

NASA Astrophysics Data System (ADS)

Budde, Adam; Nilsen, Roy; Nett, Brian

2014-03-01

State of the art automatic exposure control modulates the tube current across view angle and Z based on patient anatomy for use in axial full scan reconstructions. Cardiac CT, however, uses a fundamentally different image reconstruction that applies a temporal weighting to reduce motion artifacts. This paper describes a phase based mA modulation that goes beyond axial and ECG modulation; it uses knowledge of the temporal view weighting applied within the reconstruction algorithm to improve dose efficiency in cardiac CT scanning. Using physical phantoms and synthetic noise emulation, we measure how knowledge of sinogram temporal weighting and the prescribed cardiac phase can be used to improve dose efficiency. First, we validated that a synthetic CT noise emulation method produced realistic image noise. Next, we used the CT noise emulation method to simulate mA modulation on scans of a physical anthropomorphic phantom where a motion profile corresponding to a heart rate of 60 beats per minute was used. The CT noise emulation method matched noise to lower dose scans across the image within 1.5% relative error. Using this noise emulation method to simulate modulating the mA while keeping the total dose constant, the image variance was reduced by an average of 11.9% on a scan with 50 msec padding, demonstrating improved dose efficiency. Radiation dose reduction in cardiac CT can be achieved while maintaining the same level of image noise through phase based dose modulation that incorporates knowledge of the cardiac reconstruction algorithm.

Dual-Gated Motion-Frozen Cardiac PET with Flurpiridaz F 18.

PubMed

Slomka, Piotr J; Rubeaux, Mathieu; Le Meunier, Ludovic; Dey, Damini; Lazewatsky, Joel L; Pan, Tinsu; Dweck, Marc R; Newby, David E; Germano, Guido; Berman, Daniel S

2015-12-01

A novel PET radiotracer, Flurpiridaz F 18, has undergone phase II clinical trial evaluation as a high-resolution PET cardiac perfusion imaging agent. In a subgroup of patients imaged with this agent, we assessed the feasibility and benefit of simultaneous correction of respiratory and cardiac motion. In 16 patients, PET imaging was performed on a 4-ring scanner in dual cardiac and respiratory gating mode. Four sets of data were reconstructed with high-definition reconstruction (HD•PET): ungated and 8-bin electrocardiography-gated images using 5-min acquisition, optimal respiratory gating (ORG)-as developed for oncologic imaging-using a narrow range of breathing amplitude around end-expiration level with 35% of the counts in a 7-min acquisition, and 4-bin respiration-gated and 8-bin electrocardiography-gated images (32 bins in total) using the 7-min acquisition (dual-gating, using all data). Motion-frozen (MF) registration algorithms were applied to electrocardiography-gated and dual-gated data, creating cardiac-MF and dual-MF images. We computed wall thickness, wall/cavity contrast, and contrast-to-noise ratio for standard, ORG, cardiac-MF, and dual-MF images to assess image quality. The wall/cavity contrast was similar for ungated (9.3 ± 2.9) and ORG (9.5 ± 3.2) images and improved for cardiac-MF (10.8 ± 3.6) and dual-MF images (14.8 ± 8.0) (P < 0.05). The contrast-to-noise ratio was 22.2 ± 9.1 with ungated, 24.7 ± 12.2 with ORG, 35.5 ± 12.8 with cardiac-MF, and 42.1 ± 13.2 with dual-MF images (all P < 0.05). The wall thickness was significantly decreased (P < 0.05) with dual-MF (11.6 ± 1.9 mm) compared with ungated (13.9 ± 2.8 mm), ORG (13.1 ± 2.9 mm), and cardiac-MF images (12.1 ± 2.7 mm). Dual (respiratory/cardiac)-gated perfusion imaging with Flurpiridaz F 18 is feasible and improves image resolution, contrast, and contrast-to-noise ratio when MF registration methods are applied. © 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Optically gated beating-heart imaging

PubMed Central

Taylor, Jonathan M.

2014-01-01

The constant motion of the beating heart presents an obstacle to clear optical imaging, especially 3D imaging, in small animals where direct optical imaging would otherwise be possible. Gating techniques exploit the periodic motion of the heart to computationally “freeze” this movement and overcome motion artifacts. Optically gated imaging represents a recent development of this, where image analysis is used to synchronize acquisition with the heartbeat in a completely non-invasive manner. This article will explain the concept of optical gating, discuss a range of different implementation strategies and their strengths and weaknesses. Finally we will illustrate the usefulness of the technique by discussing applications where optical gating has facilitated novel biological findings by allowing 3D in vivo imaging of cardiac myocytes in their natural environment of the beating heart. PMID:25566083

Predicting motion sickness during parabolic flight

NASA Technical Reports Server (NTRS)

Harm, Deborah L.; Schlegel, Todd T.

2002-01-01

BACKGROUND: There are large individual differences in susceptibility to motion sickness. Attempts to predict who will become motion sick have had limited success. In the present study, we examined gender differences in resting levels of salivary amylase and total protein, cardiac interbeat intervals (R-R intervals), and a sympathovagal index and evaluated their potential to correctly classify individuals into two motion sickness severity groups. METHODS: Sixteen subjects (10 men and 6 women) flew four sets of 10 parabolas aboard NASA's KC-135 aircraft. Saliva samples for amylase and total protein were collected preflight on the day of the flight and motion sickness symptoms were recorded during each parabola. Cardiovascular parameters were collected in the supine position 1-5 days before the flight. RESULTS: There were no significant gender differences in sickness severity or any of the other variables mentioned above. Discriminant analysis using salivary amylase, R-R intervals and the sympathovagal index produced a significant Wilks' lambda coefficient of 0.36, p=0.006. The analysis correctly classified 87% of the subjects into the none-mild sickness or the moderate-severe sickness group. CONCLUSIONS: The linear combination of resting levels of salivary amylase, high-frequency R-R interval levels, and a sympathovagal index may be useful in predicting motion sickness severity.

Predicting Motion Sickness During Parabolic Flight

NASA Technical Reports Server (NTRS)

Harm, Deborah L.; Schlegel, Todd T.

2002-01-01

Background: There are large individual differences in susceptibility to motion sickness. Attempts to predict who will become motion sick have had limited success. In the present study we examined gender differences in resting levels of salivary amylase and total protein, cardiac interbeat intervals (R-R intervals), and a sympathovagal index and evaluated their potential to correctly classify individuals into two motion sickness severity groups. Methods: Sixteen subjects (10 men and 6 women) flew 4 sets of 10 parabolas aboard NASA's KC-135 aircraft. Saliva samples for amylase and total protein were collected preflight on the day of the flight and motion sickness symptoms were recorded during each parabola. Cardiovascular parameters were collected in the supine position 1-5 days prior to the flight. Results: There were no significant gender differences in sickness severity or any of the other variables mentioned above. Discriminant analysis using salivary amylase, R-R intervals and the sympathovagal index produced a significant Wilks' lambda coefficient of 0.36, p= 0.006. The analysis correctly classified 87% of the subjects into the none-mild sickness or the moderate-severe sickness group. Conclusions: The linear combination of resting levels of salivary amylase, high frequency R-R interval levels, and a sympathovagal index may be useful in predicting motion sickness severity.

CUQI: cardiac ultrasound video quality index

PubMed Central

Razaak, Manzoor; Martini, Maria G.

2016-01-01

Abstract. Medical images and videos are now increasingly part of modern telecommunication applications, including telemedicinal applications, favored by advancements in video compression and communication technologies. Medical video quality evaluation is essential for modern applications since compression and transmission processes often compromise the video quality. Several state-of-the-art video quality metrics used for quality evaluation assess the perceptual quality of the video. For a medical video, assessing quality in terms of “diagnostic” value rather than “perceptual” quality is more important. We present a diagnostic-quality–oriented video quality metric for quality evaluation of cardiac ultrasound videos. Cardiac ultrasound videos are characterized by rapid repetitive cardiac motions and distinct structural information characteristics that are explored by the proposed metric. Cardiac ultrasound video quality index, the proposed metric, is a full reference metric and uses the motion and edge information of the cardiac ultrasound video to evaluate the video quality. The metric was evaluated for its performance in approximating the quality of cardiac ultrasound videos by testing its correlation with the subjective scores of medical experts. The results of our tests showed that the metric has high correlation with medical expert opinions and in several cases outperforms the state-of-the-art video quality metrics considered in our tests. PMID:27014715

Effects of intrafractional motion on water equivalent pathlength in respiratory-gated heavy charged particle beam radiotherapy.

PubMed

Mori, Shinichiro; Chen, George T Y; Endo, Masahiro

2007-09-01

To analyze the water equivalent pathlength (WEL) fluctuations resulting from cardiac motion and display these variations on a beam's-eye-view image; the analysis provides insight into the accuracy of lung tumor irradiation with heavy charged particle beams. Volumetric cine computed tomography (CT) images were obtained on 7 lung cancer patients under free-breathing conditions with a 256-multislice CT scanner. Cardiac phase was determined by selecting systole and diastole. A WEL difference image (DeltaWEL) was calculated by subtracting the WEL image at end-systole from that at end-diastole at respiratory exhalation phase. Two calculation regions were defined: Region 1 was limited to the volume defined by planes bounding the heart; Region 2 included the entire body thickness for a given beam's-eye-view angle. The DeltaWEL values observed in Region 1 showed fluctuations at the periphery of the heart that varied from 20.4 (SD, 5.2) mm WEL to -15.6 (3.2) mm WEL. The areas over which these range perturbation values were observed were 36.8 (32.4) mm(2) and 6.0 (2.8) mm(2) for positive and negative WEL, respectively. The WEL fluctuations in Region 2 increased by approximately 3-4 mm WEL, whereas negative WEL fluctuations changed by approximately -4 to -5 mm WEL, compared with WEL for Region 1; areas over 20 mm WEL changes in Region 2 increased by 9 mm(2) for positive DeltaWEL and 2 mm(2) for negative DeltaWEL. Cine CT with a 256-multislice CT scanner captures both volumetric cardiac and respiratory motion with a temporal resolution sufficient to estimate range fluctuations by these motions. This information can be used to assess the range perturbations that charged particle beams may experience in irradiation of lung or esophageal tumors adjacent to the heart.

Simultaneous total cavopulmonary connection and cardiac re-synchronisation therapy.

PubMed

Nakanishi, Keisuke; Kawasaki, Shiori; Amano, Atsushi

2017-08-01

We report the simultaneous use of cardiac re-synchronisation therapy and total cavopulmonary connection in a patient with dyssynchrony, wide QRS, and cardiac failure. To our knowledge, this simultaneous approach has not been reported previously. On follow-up, we noted that QRS width and brain natriuretic peptide levels improved. In addition, speckle tracking revealed improved synchronisation of ventricular wall motion.

Wavelet-space correlation imaging for high-speed MRI without motion monitoring or data segmentation.

PubMed

Li, Yu; Wang, Hui; Tkach, Jean; Roach, David; Woods, Jason; Dumoulin, Charles

2015-12-01

This study aims to (i) develop a new high-speed MRI approach by implementing correlation imaging in wavelet-space, and (ii) demonstrate the ability of wavelet-space correlation imaging to image human anatomy with involuntary or physiological motion. Correlation imaging is a high-speed MRI framework in which image reconstruction relies on quantification of data correlation. The presented work integrates correlation imaging with a wavelet transform technique developed originally in the field of signal and image processing. This provides a new high-speed MRI approach to motion-free data collection without motion monitoring or data segmentation. The new approach, called "wavelet-space correlation imaging", is investigated in brain imaging with involuntary motion and chest imaging with free-breathing. Wavelet-space correlation imaging can exceed the speed limit of conventional parallel imaging methods. Using this approach with high acceleration factors (6 for brain MRI, 16 for cardiac MRI, and 8 for lung MRI), motion-free images can be generated in static brain MRI with involuntary motion and nonsegmented dynamic cardiac/lung MRI with free-breathing. Wavelet-space correlation imaging enables high-speed MRI in the presence of involuntary motion or physiological dynamics without motion monitoring or data segmentation. © 2014 Wiley Periodicals, Inc.

Wavelet-space Correlation Imaging for High-speed MRI without Motion Monitoring or Data Segmentation

PubMed Central

Li, Yu; Wang, Hui; Tkach, Jean; Roach, David; Woods, Jason; Dumoulin, Charles

2014-01-01

Purpose This study aims to 1) develop a new high-speed MRI approach by implementing correlation imaging in wavelet-space, and 2) demonstrate the ability of wavelet-space correlation imaging to image human anatomy with involuntary or physiological motion. Methods Correlation imaging is a high-speed MRI framework in which image reconstruction relies on quantification of data correlation. The presented work integrates correlation imaging with a wavelet transform technique developed originally in the field of signal and image processing. This provides a new high-speed MRI approach to motion-free data collection without motion monitoring or data segmentation. The new approach, called “wavelet-space correlation imaging”, is investigated in brain imaging with involuntary motion and chest imaging with free-breathing. Results Wavelet-space correlation imaging can exceed the speed limit of conventional parallel imaging methods. Using this approach with high acceleration factors (6 for brain MRI, 16 for cardiac MRI and 8 for lung MRI), motion-free images can be generated in static brain MRI with involuntary motion and nonsegmented dynamic cardiac/lung MRI with free-breathing. Conclusion Wavelet-space correlation imaging enables high-speed MRI in the presence of involuntary motion or physiological dynamics without motion monitoring or data segmentation. PMID:25470230

Effects of eating on vection-induced motion sickness, cardiac vagal tone, and gastric myoelectric activity

NASA Technical Reports Server (NTRS)

Uijtdehaage, S. H.; Stern, R. M.; Koch, K. L.

1992-01-01

This study investigated the effect of food ingestion on motion sickness severity and its physiological mechanisms. Forty-six fasted subjects were assigned either to a meal group or to a no-meal group. Electrogastrographic (EGG) indices (normal 3 cpm activity and abnormal 4-9 cpm tachyarrhythmia) and respiratory sinus arrhythmia (RSA) were measured before and after a meal and during a subsequent exposure to a rotating drum in which illusory self-motion was induced. The results indicated that food intake enhanced cardiac parasympathetic tone (RSA) and increased gastric 3 cpm activity. Postprandial effects on motion sickness severity remain equivocal due to group differences in RSA baseline levels. During drum rotation, dysrhythmic activity of the stomach (tachyarrhythmia) and vagal withdrawal were observed. Furthermore, high levels of vagal tone prior to drum rotation predicted a low incidence of motion sickness symptoms, and were associated positively with gastric 3 cpm activity and negatively with tachyarrhythmia. These data suggest that enhanced levels of parasympathetic activity can alleviate motion sickness symptoms by suppressing, in part, its dysrhythmic gastric underpinnings.

Gastric myoelectrical and autonomic cardiac reactivity to laboratory stressors

PubMed Central

GIANAROS, PETER J.; QUIGLEY, KAREN S.; MORDKOFF, J. TOBY; STERN, ROBERT M.

2010-01-01

We evaluated the effects of two laboratory stressors (speech preparation and isometric handgrip) on gastric myoelectrical and autonomic cardiac activity, and the extent to which autonomic responses to these stressors and somatization predict reports of motion sickness during exposure to a rotating optokinetic drum. Both stressors prompted a decrease in preejection period (PEP) and respiratory sinus arrhythmia (RSA), and an increase in a dysrhythmic pattern of gastric myoelectrical activity, termed gastric tachyarrhythmia. Stressor-induced decreases in RSA and higher somatization scores predicted increased reports of motion sickness during drum rotation. These results demonstrate that laboratory stressors concurrently affect gastric myoelectrical activity and autonomic control of the heart, and that stressor-induced decreases in RSA and higher levels of somatization predict motion sickness susceptibility. PMID:11446577

In vivo dose measurement using TLDs and MOSFET dosimeters for cardiac radiosurgery.

PubMed

Gardner, Edward A; Sumanaweera, Thilaka S; Blanck, Oliver; Iwamura, Alyson K; Steel, James P; Dieterich, Sonja; Maguire, Patrick

2012-05-10

In vivo measurements were made of the dose delivered to animal models in an effort to develop a method for treating cardiac arrhythmia using radiation. This treatment would replace RF energy (currently used to create cardiac scar) with ionizing radiation. In the current study, the pulmonary vein ostia of animal models were irradiated with 6 MV X-rays in order to produce a scar that would block aberrant signals characteristic of atrial fibrillation. The CyberKnife radiosurgery system was used to deliver planned treatments of 20-35 Gy in a single fraction to four animals. The Synchrony system was used to track respiratory motion of the heart, while the contractile motion of the heart was untracked. The dose was measured on the epicardial surface near the right pulmonary vein and on the esophagus using surgically implanted TLD dosimeters, or in the coronary sinus using a MOSFET dosimeter placed using a catheter. The doses measured on the epicardium with TLDs averaged 5% less than predicted for those locations, while doses measured in the coronary sinus with the MOSFET sensor nearest the target averaged 6% less than the predicted dose. The measurements on the esophagus averaged 25% less than predicted. These results provide an indication of the accuracy with which the treatment planning methods accounted for the motion of the target, with its respiratory and cardiac components. This is the first report on the accuracy of CyberKnife dose delivery to cardiac targets.

The potential of multi-slice computed tomography based volumetry for demonstrating reverse remodeling induced by cardiac resynchronization therapy.

PubMed

Langer, Christoph; Schroeder, Janina; Peterschroeder, Andreas; Vaske, Bernhard; Faber, Lothar; Welge, Dirk; Niethammer, Matthias; Lamp, Barbara; Butz, Thomas; Bitter, Thomas; Oldenburg, Olaf; Horstkotte, Dieter

2010-07-01

Multi-slice computed tomography (MSCT) was proved to provide precise cardiac volumetric assessment. Cardiac resynchronization therapy (CRT) is an effective treatment for selected patients with heart failure and reduced ejection fraction (HFREF). In HFREF patients we investigated the potential of MSCT based wall motion analysis in order to demonstrate CRT-induced reversed remodeling. Besides six patients with normal cardiac pump function serving as control group seven HFREF patients underwent contrast enhanced MSCT before and after CRT. Short cardiac axis views of the left ventricle (LV) in end-diastole (ED) and end-systole (ES) served for planimetry. Pre- and post-CRT MSCT based volumetry was compared with 2D echo. To demonstrate CRT-induced reverse remodeling, MSCT based multi-segment color-coded polar maps were introduced. With regard to the HFREF patients pre-CRT MSCT based volumetry correlated with 2D echo data for LV-EDV (MSCT 278.3+/-75.0mL vs. echo 274.4+/-85.6mL) r=0.380, p=0.401, LV-ESV (MSCT 226.7+/-75.4mL vs. echo 220.1+/-74.0mL) r=0.323, p=0.479 and LV-EF (MSCT 20.2+/-8.8% vs. echo 20.0+/-11.9%) r=0.617, p=0.143. Post-CRT MSCT correlated well with 2D echo: LV-EDV (MSCT 218.9+/-106.4mL vs. echo 188.7+/-93.1mL) r=0.87, p=0.011, LV-ESV (MSCT 145+/-71.5mL vs. echo 125.6+/-78mL) r=0.84, p=0.018 and LV-EF (MSCT 29.6+/-11.3mL vs. echo 38.6+/-14.6mL) r=0.89, p=0.007. There was a significant increase of the mid-ventricular septum in terms of absolute LV wall thickening of the responders (pre 0.9+/-2.1mm vs. post 3.3+/-2.2mm; p<0.0005). MSCT based volumetry involving multi-segment color-coded polar maps offers wall motion analysis to demonstrate CRT-induced reverse remodeling which needs to be further validated. 2010 Elsevier Ltd. All rights reserved.

An MR-based Model for Cardio-Respiratory Motion Compensation of Overlays in X-Ray Fluoroscopy

PubMed Central

Fischer, Peter; Faranesh, Anthony; Pohl, Thomas; Maier, Andreas; Rogers, Toby; Ratnayaka, Kanishka; Lederman, Robert; Hornegger, Joachim

2017-01-01

In X-ray fluoroscopy, static overlays are used to visualize soft tissue. We propose a system for cardiac and respiratory motion compensation of these overlays. It consists of a 3-D motion model created from real-time MR imaging. Multiple sagittal slices are acquired and retrospectively stacked to consistent 3-D volumes. Slice stacking considers cardiac information derived from the ECG and respiratory information extracted from the images. Additionally, temporal smoothness of the stacking is enhanced. Motion is estimated from the MR volumes using deformable 3-D/3-D registration. The motion model itself is a linear direct correspondence model using the same surrogate signals as slice stacking. In X-ray fluoroscopy, only the surrogate signals need to be extracted to apply the motion model and animate the overlay in real time. For evaluation, points are manually annotated in oblique MR slices and in contrast-enhanced X-ray images. The 2-D Euclidean distance of these points is reduced from 3.85 mm to 2.75 mm in MR and from 3.0 mm to 1.8 mm in X-ray compared to the static baseline. Furthermore, the motion-compensated overlays are shown qualitatively as images and videos. PMID:28692969

Distribution of late gadolinium enhancement in various types of cardiomyopathies: Significance in differential diagnosis, clinical features and prognosis.

PubMed

Satoh, Hiroshi; Sano, Makoto; Suwa, Kenichiro; Saitoh, Takeji; Nobuhara, Mamoru; Saotome, Masao; Urushida, Tsuyoshi; Katoh, Hideki; Hayashi, Hideharu

2014-07-26

The recent development of cardiac magnetic resonance (CMR) techniques has allowed detailed analyses of cardiac function and tissue characterization with high spatial resolution. We review characteristic CMR features in ischemic and non-ischemic cardiomyopathies (ICM and NICM), especially in terms of the location and distribution of late gadolinium enhancement (LGE). CMR in ICM shows segmental wall motion abnormalities or wall thinning in a particular coronary arterial territory, and the subendocardial or transmural LGE. LGE in NICM generally does not correspond to any particular coronary artery distribution and is located mostly in the mid-wall to subepicardial layer. The analysis of LGE distribution is valuable to differentiate NICM with diffusely impaired systolic function, including dilated cardiomyopathy, end-stage hypertrophic cardiomyopathy (HCM), cardiac sarcoidosis, and myocarditis, and those with diffuse left ventricular (LV) hypertrophy including HCM, cardiac amyloidosis and Anderson-Fabry disease. A transient low signal intensity LGE in regions of severe LV dysfunction is a particular feature of stress cardiomyopathy. In arrhythmogenic right ventricular cardiomyopathy/dysplasia, an enhancement of right ventricular (RV) wall with functional and morphological changes of RV becomes apparent. Finally, the analyses of LGE distribution have potentials to predict cardiac outcomes and response to treatments.

Use of self-gated radial cardiovascular magnetic resonance to detect and classify arrhythmias (atrial fibrillation and premature ventricular contraction).

PubMed

Piekarski, Eve; Chitiboi, Teodora; Ramb, Rebecca; Feng, Li; Axel, Leon

2016-11-25

Arrhythmia can significantly alter the image quality of cardiovascular magnetic resonance (CMR); automatic detection and sorting of the most frequent types of arrhythmias during the CMR acquisition could potentially improve image quality. New CMR techniques, such as non-Cartesian CMR, can allow self-gating: from cardiac motion-related signal changes, we can detect cardiac cycles without an electrocardiogram. We can further use this data to obtain a surrogate for RR intervals (valley intervals: VV). Our purpose was to evaluate the feasibility of an automated method for classification of non-arrhythmic (NA) (regular cycles) and arrhythmic patients (A) (irregular cycles), and for sorting of common arrhythmia patterns between atrial fibrillation (AF) and premature ventricular contraction (PVC), using the cardiac motion-related signal obtained during self-gated free-breathing radial cardiac cine CMR with compressed sensing reconstruction (XD-GRASP). One hundred eleven patients underwent cardiac XD-GRASP CMR between October 2015 and February 2016; 33 were included for retrospective analysis with the proposed method (6 AF, 8 PVC, 19 NA; by recent ECG). We analyzed the VV, using pooled statistics (histograms) and sequential analysis (Poincaré plots), including the median (medVV), the weighted mean (meanVV), the total number of VV values (VVval), and the total range (VVTR) and half range (VVHR) of the cumulative frequency distribution of VV, including the median to half range (medVV/VVHR) and the half range to total range (VVHR/VVTR) ratios. We designed a simple algorithm for using the VV results to differentiate A from NA, and AF from PVC. Between NA and A, meanVV, VVval, VVTR, VVHR, medVV/VVHR and VVHR/VVTR ratios were significantly different (p values = 0.00014, 0.0027, 0.000028, 5×10 -9 , 0.002, respectively). Between AF and PVC, meanVV, VVval and medVV/VVHR ratio were significantly different (p values = 0.018, 0.007, 0.044, respectively). Using our algorithm, sensitivity, specificity, and accuracy were 93 %, 95 % and 94 % to discriminate between NA and A, and 83 %, 71 %, and 77 % to discriminate between AF and PVC, respectively; areas under the ROC curve were 0.93 and 0.89. Our study shows we can reliably detect arrhythmias and differentiate AF from PVC, using self-gated cardiac cine XD-GRASP CMR.

Fast left ventricle tracking in CMR images using localized anatomical affine optical flow

NASA Astrophysics Data System (ADS)

Queirós, Sandro; Vilaça, João. L.; Morais, Pedro; Fonseca, Jaime C.; D'hooge, Jan; Barbosa, Daniel

2015-03-01

In daily cardiology practice, assessment of left ventricular (LV) global function using non-invasive imaging remains central for the diagnosis and follow-up of patients with cardiovascular diseases. Despite the different methodologies currently accessible for LV segmentation in cardiac magnetic resonance (CMR) images, a fast and complete LV delineation is still limitedly available for routine use. In this study, a localized anatomically constrained affine optical flow method is proposed for fast and automatic LV tracking throughout the full cardiac cycle in short-axis CMR images. Starting from an automatically delineated LV in the end-diastolic frame, the endocardial and epicardial boundaries are propagated by estimating the motion between adjacent cardiac phases using optical flow. In order to reduce the computational burden, the motion is only estimated in an anatomical region of interest around the tracked boundaries and subsequently integrated into a local affine motion model. Such localized estimation enables to capture complex motion patterns, while still being spatially consistent. The method was validated on 45 CMR datasets taken from the 2009 MICCAI LV segmentation challenge. The proposed approach proved to be robust and efficient, with an average distance error of 2.1 mm and a correlation with reference ejection fraction of 0.98 (1.9 +/- 4.5%). Moreover, it showed to be fast, taking 5 seconds for the tracking of a full 4D dataset (30 ms per image). Overall, a novel fast, robust and accurate LV tracking methodology was proposed, enabling accurate assessment of relevant global function cardiac indices, such as volumes and ejection fraction

Dynamic characteristic mechanism of atrial septal defect using real-time three-dimensional echocardiography and evaluation of right ventricular functions.

PubMed

Sharen, Gao-Wa; Zhang, Jun; Qin, Chuan; Lv, Qing

2017-02-01

The dynamic characteristics of the area of the atrial septal defect (ASD) were evaluated using the technique of real-time three-dimensional echocardiography (RT 3DE), the potential factors responsible for the dynamic characteristics of the area of ASD were observed, and the overall and local volume and functions of the patients with ASD were measured. RT 3DE was performed on the 27 normal controls and 28 patients with ASD. Based on the three-dimensional data workstations, the area of ASD was measured at P wave vertex, R wave vertex, T wave starting point, and T wave terminal point and in the T-P section. The right atrial volume in the same time phase of the cardiac cycle and the motion displacement distance of the tricuspid annulus in the corresponding period were measured. The measured value of the area of ASD was analyzed. The changes in the right atrial volume and the motion displacement distance of the tricuspid annulus in the normal control group and the ASD group were compared. The right ventricular ejection fractions in the normal control group and the ASD group were compared using the RT 3DE long-axis eight-plane (LA 8-plane) method. Real-time three-dimensional volume imaging was performed in the normal control group and ASD group (n=30). The right ventricular inflow tract, outflow tract, cardiac apex muscular trabecula dilatation, end-systolic volume, overall dilatation, end-systolic volume, and appropriate local and overall ejection fractions in both two groups were measured with the four-dimensional right ventricular quantitative analysis method (4D RVQ) and compared. The overall right ventricular volume and the ejection fraction measured by the LA 8-plane method and 4D RVQ were subjected to a related analysis. Dynamic changes occurred to the area of ASD in the cardiac cycle. The rules for dynamic changes in the area of ASD and the rules for changes in the right atrial volume in the cardiac cycle were consistent. The maximum value of the changes in the right atrial volume occurred in the end-systolic period when the peak of the curve appeared. The minimum value of the changes occurred in the end-systolic period and was located at the lowest point of the volume variation curve. The area variation curve for ASD and the motion variation curve for the tricuspid annulus in the cardiac cycle were the same. The displacement of the tricuspid annulus exhibited directionality. The measured values of the area of ASD at P wave vertex, R wave vertex, T wave starting point, T wave terminal point and in the T-P section were properly correlated with the right atrial volume (P<0.001). The area of ASD and the motion displacement distance of the tricuspid annulus were negatively correlated (P<0.05). The right atrial volumes in the ASD group in the cardiac cycle in various time phases increased significantly as compared with those in the normal control group (P=0.0001). The motion displacement distance of the tricuspid annulus decreased significantly in the ASD group as compared with that in the normal control group (P=0.043). The right ventricular ejection fraction in the ASD group was lower than that in the normal control group (P=0.032). The ejection fraction of the cardiac apex trabecula of the ASD patients was significantly lower than the ejection fractions of the right ventricular outflow tract and inflow tract and overall ejection fraction. The difference was statistically significant (P=0.005). The right ventricular local and overall dilatation and end-systolic volumes in the ASD group increased significantly as compared with those in the normal control group (P=0.031). The aRVEF and the overall ejection fraction decreased in the ASD group as compared with those in the normal control group (P=0.0005). The dynamic changes in the area of ASD and the motion curves for the right atrial volume and tricuspid annulus have the same dynamic characteristics. RT 3DE can be used to accurately evaluate the local and overall volume and functions of the right ventricle. The local and overall volume loads of the right ventricle in the ASD patients increase significantly as compared with those of the normal people. The right ventricular cardiac apex and the overall systolic function decrease.

Automatic generation of endocardial surface meshes with 1-to-1 correspondence from cine-MR images

NASA Astrophysics Data System (ADS)

Su, Yi; Teo, S.-K.; Lim, C. W.; Zhong, L.; Tan, R. S.

2015-03-01

In this work, we develop an automatic method to generate a set of 4D 1-to-1 corresponding surface meshes of the left ventricle (LV) endocardial surface which are motion registered over the whole cardiac cycle. These 4D meshes have 1- to-1 point correspondence over the entire set, and is suitable for advanced computational processing, such as shape analysis, motion analysis and finite element modelling. The inputs to the method are the set of 3D LV endocardial surface meshes of the different frames/phases of the cardiac cycle. Each of these meshes is reconstructed independently from border-delineated MR images and they have no correspondence in terms of number of vertices/points and mesh connectivity. To generate point correspondence, the first frame of the LV mesh model is used as a template to be matched to the shape of the meshes in the subsequent phases. There are two stages in the mesh correspondence process: (1) a coarse matching phase, and (2) a fine matching phase. In the coarse matching phase, an initial rough matching between the template and the target is achieved using a radial basis function (RBF) morphing process. The feature points on the template and target meshes are automatically identified using a 16-segment nomenclature of the LV. In the fine matching phase, a progressive mesh projection process is used to conform the rough estimate to fit the exact shape of the target. In addition, an optimization-based smoothing process is used to achieve superior mesh quality and continuous point motion.

Atlas-Based Ventricular Shape Analysis for Understanding Congenital Heart Disease.

PubMed

Farrar, Genevieve; Suinesiaputra, Avan; Gilbert, Kathleen; Perry, James C; Hegde, Sanjeet; Marsden, Alison; Young, Alistair A; Omens, Jeffrey H; McCulloch, Andrew D

2016-12-01

Congenital heart disease is associated with abnormal ventricular shape that can affect wall mechanics and may be predictive of long-term adverse outcomes. Atlas-based parametric shape analysis was used to analyze ventricular geometries of eight adolescent or adult single-ventricle CHD patients with tricuspid atresia and Fontans. These patients were compared with an "atlas" of non-congenital asymptomatic volunteers, resulting in a set of z-scores which quantify deviations from the control population distribution on a patient-by-patient basis. We examined the potential of these scores to: (1) quantify abnormalities of ventricular geometry in single ventricle physiologies relative to the normal population; (2) comprehensively quantify wall motion in CHD patients; and (3) identify possible relationships between ventricular shape and wall motion that may reflect underlying functional defects or remodeling in CHD patients. CHD ventricular geometries at end-diastole and end-systole were individually compared with statistical shape properties of an asymptomatic population from the Cardiac Atlas Project. Shape analysis-derived model properties, and myocardial wall motions between end-diastole and end-systole, were compared with physician observations of clinical functional parameters. Relationships between altered shape and altered function were evaluated via correlations between atlas-based shape and wall motion scores. Atlas-based shape analysis identified a diverse set of specific quantifiable abnormalities in ventricular geometry or myocardial wall motion in all subjects. Moreover, this initial cohort displayed significant relationships between specific shape abnormalities such as increased ventricular sphericity and functional defects in myocardial deformation, such as decreased long-axis wall motion. These findings suggest that atlas-based ventricular shape analysis may be a useful new tool in the management of patients with CHD who are at risk of impaired ventricular wall mechanics and chamber remodeling.

A novel dual gating approach using joint inertial sensors: implications for cardiac PET imaging

NASA Astrophysics Data System (ADS)

Jafari Tadi, Mojtaba; Teuho, Jarmo; Lehtonen, Eero; Saraste, Antti; Pänkäälä, Mikko; Koivisto, Tero; Teräs, Mika

2017-10-01

Positron emission tomography (PET) is a non-invasive imaging technique which may be considered as the state of art for the examination of cardiac inflammation due to atherosclerosis. A fundamental limitation of PET is that cardiac and respiratory motions reduce the quality of the achieved images. Current approaches for motion compensation involve gating the PET data based on the timing of quiescent periods of cardiac and respiratory cycles. In this study, we present a novel gating method called microelectromechanical (MEMS) dual gating which relies on joint non-electrical sensors, i.e. tri-axial accelerometer and gyroscope. This approach can be used for optimized selection of quiescent phases of cardiac and respiratory cycles. Cardiomechanical activity according to echocardiography observations was investigated to confirm whether this dual sensor solution can provide accurate trigger timings for cardiac gating. Additionally, longitudinal chest motions originating from breathing were measured by accelerometric- and gyroscopic-derived respiratory (ADR and GDR) tracking. The ADR and GDR signals were evaluated against Varian real-time position management (RPM) signals in terms of amplitude and phase. Accordingly, high linear correlation and agreement were achieved between the reference electrocardiography, RPM, and measured MEMS signals. We also performed a Ge-68 phantom study to evaluate possible metal artifacts caused by the integrated read-out electronics including mechanical sensors and semiconductors. The reconstructed phantom images did not reveal any image artifacts. Thus, it was concluded that MEMS-driven dual gating can be used in PET studies without an effect on the quantitative or visual accuracy of the PET images. Finally, the applicability of MEMS dual gating for cardiac PET imaging was investigated with two atherosclerosis patients. Dual gated PET images were successfully reconstructed using only MEMS signals and both qualitative and quantitative assessments revealed encouraging results that warrant further investigation of this method.

Coronary calcium visualization using dual energy chest radiography with sliding organ registration

NASA Astrophysics Data System (ADS)

Wen, Di; Nye, Katelyn; Zhou, Bo; Gilkeson, Robert C.; Wilson, David L.

2016-03-01

Coronary artery calcification (CAC) is the lead biomarker for atherosclerotic heart disease. We are developing a new technique to image CAC using ubiquitously ordered, low cost, low radiation dual energy (DE) chest radiography (using the two-shot GE Revolution XRd system). In this paper, we proposed a novel image processing method (CorCalDx) based on sliding organ registration to create a bone-image-like, coronary calcium image (CCI) that significantly reduces motion artifacts and improves CAC conspicuity. Experiments on images of a physical dynamic cardiac phantom showed that CorCalDx reduced 73% of the motion artifact area as compared to standard DE over a range of heart rates up to 90 bpm and varying x-ray radiation exposures. Residual motion artifact in the phantom CCI is greatly suppressed in gray level and area (0.88% of the heart area). In a Functional Measurement Test (FMT) with 20 clinical exams, image quality improvement of CorCalDx against standard DE (measured from -10 to +10) was significantly suggested (p<0.0001) by three radiologists for cardiac motion artifacts (7.2+/-2.1) and cardiac anatomy visibility (6.1+/-3.5). CorCalDx was always chosen best in every image tested. In preliminary assessments of 12 patients with 18 calcifications, 90% of motion artifact regions in standard DE results were removed in CorCalDx results, with 100% sensitivity of calcification detection, showing great potential of CorCalDx to improve CAC detection and grading in DE chest radiography.

A novel Bayesian respiratory motion model to estimate and resolve uncertainty in image-guided cardiac interventions.

PubMed

Peressutti, Devis; Penney, Graeme P; Housden, R James; Kolbitsch, Christoph; Gomez, Alberto; Rijkhorst, Erik-Jan; Barratt, Dean C; Rhode, Kawal S; King, Andrew P

2013-05-01

In image-guided cardiac interventions, respiratory motion causes misalignments between the pre-procedure roadmap of the heart used for guidance and the intra-procedure position of the heart, reducing the accuracy of the guidance information and leading to potentially dangerous consequences. We propose a novel technique for motion-correcting the pre-procedural information that combines a probabilistic MRI-derived affine motion model with intra-procedure real-time 3D echocardiography (echo) images in a Bayesian framework. The probabilistic model incorporates a measure of confidence in its motion estimates which enables resolution of the potentially conflicting information supplied by the model and the echo data. Unlike models proposed so far, our method allows the final motion estimate to deviate from the model-produced estimate according to the information provided by the echo images, so adapting to the complex variability of respiratory motion. The proposed method is evaluated using gold-standard MRI-derived motion fields and simulated 3D echo data for nine volunteers and real 3D live echo images for four volunteers. The Bayesian method is compared to 5 other motion estimation techniques and results show mean/max improvements in estimation accuracy of 10.6%/18.9% for simulated echo images and 20.8%/41.5% for real 3D live echo data, over the best comparative estimation method. Copyright © 2013 Elsevier B.V. All rights reserved.

SU-F-T-673: Effects of Cardiac Induced Brain Pulsations On Proton Minibeams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eagle, J; Marsh, S; Lee, E

Purpose: To quantify the dosimetric impact of internal motion within the brain on spatially modulated proton minibeam radiation therapy (pMRT) for small animal research. Methods: The peak-to-valley dose ratio (PVDR) is an essential dosimetric factor for pMRT. Motion of an animal brain caused by cardiac-induced pulsations (CIP) can impact dose deposition. For synchrotron generated high dose rate X-ray microbeams this effect is evaded due to the quasi-instantaneous delivery. By comparison, pMRT potentially suffers increased spread due to lower dose rates. However, for a given dose rate it is less susceptible to beam spread than microbeams, due to the spatial modulationmore » being an order of magnitude larger. Monte Carlo simulations in TOPAS were used to model the beam spread for a 50.5MeV pMRT beam. Motion effects were simulated for a 50mm thick brass collimator with 0.3mm slit width and 1.0mm center-to-center spacing in a water phantom. The maximum motion in a rat brain due to CIP has been reported to be 0.06mm. Motion was simulated with a peak amplitude in the range 0–0.2mm. Results: The impact of 0.06mm peak motion was minimal and reduced the PVDR by about 1% at a depth of 10mm. For 0.2mm peak motion the PVDR was reduced by 16% at a depth of 10mm. Conclusion: For the pMRT beam the magnitude of cardiac-induced brain motion has minimal impact on the PVDR for the investigated collimator geometry. For more narrow beams the effect is likely to be larger. This indicates that delivery of pMRT to small animal brains should not be affected considerably by beamlines with linac compatible dose rates.« less

Cardiac fluid dynamics meets deformation imaging.

PubMed

Dal Ferro, Matteo; Stolfo, Davide; De Paris, Valerio; Lesizza, Pierluigi; Korcova, Renata; Collia, Dario; Tonti, Giovanni; Sinagra, Gianfranco; Pedrizzetti, Gianni

2018-02-20

Cardiac function is about creating and sustaining blood in motion. This is achieved through a proper sequence of myocardial deformation whose final goal is that of creating flow. Deformation imaging provided valuable contributions to understanding cardiac mechanics; more recently, several studies evidenced the existence of an intimate relationship between cardiac function and intra-ventricular fluid dynamics. This paper summarizes the recent advances in cardiac flow evaluations, highlighting its relationship with heart wall mechanics assessed through the newest techniques of deformation imaging and finally providing an opinion of the most promising clinical perspectives of this emerging field. It will be shown how fluid dynamics can integrate volumetric and deformation assessments to provide a further level of knowledge of cardiac mechanics.

Echocardiographic assessment of cardiac disease

NASA Technical Reports Server (NTRS)

Popp, R. L.

1976-01-01

The physical principles and current applications of echocardiography in assessment of heart diseases are reviewed. Technical considerations and unresolved points relative to the use of echocardiography in various disease states are stressed. The discussion covers normal mitral valve motion, mitral stenosis, aortic regurgitation, atrial masses, mitral valve prolapse, and idiopathic hypertrophic subaortic stenosis. Other topics concern tricuspic valve abnormalities, aortic valve disease, pulmonic valve, pericardial effusion, intraventricular septal motion, and left ventricular function. The application of echocardiography to congenital heart disease diagnosis is discussed along with promising ultrasonic imaging systems. The utility of echocardiography in quantitative evaluation of cardiac disease is demonstrated.

In vivo dose measurement using TLDs and MOSFET dosimeters for cardiac radiosurgery

PubMed Central

Sumanaweera, Thilaka S.; Blanck, Oliver; Iwamura, Alyson K.; Steel, James P.; Dieterich, Sonja; Maguire, Patrick

2012-01-01

In vivo measurements were made of the dose delivered to animal models in an effort to develop a method for treating cardiac arrhythmia using radiation. This treatment would replace RF energy (currently used to create cardiac scar) with ionizing radiation. In the current study, the pulmonary vein ostia of animal models were irradiated with 6 MV X‐rays in order to produce a scar that would block aberrant signals characteristic of atrial fibrillation. The CyberKnife radiosurgery system was used to deliver planned treatments of 20–35 Gy in a single fraction to four animals. The Synchrony system was used to track respiratory motion of the heart, while the contractile motion of the heart was untracked. The dose was measured on the epicardial surface near the right pulmonary vein and on the esophagus using surgically implanted TLD dosimeters, or in the coronary sinus using a MOSFET dosimeter placed using a catheter. The doses measured on the epicardium with TLDs averaged 5% less than predicted for those locations, while doses measured in the coronary sinus with the MOSFET sensor nearest the target averaged 6% less than the predicted dose. The measurements on the esophagus averaged 25% less than predicted. These results provide an indication of the accuracy with which the treatment planning methods accounted for the motion of the target, with its respiratory and cardiac components. This is the first report on the accuracy of CyberKnife dose delivery to cardiac targets. PACS numbers: 87.53.Ly, 87.53.Bn PMID:22584173

Position Estimation of an Epicardial Crawling Robot on the Beating Heart by Modeling of Physiological Motion

PubMed Central

Wood, Nathan A.; del Agua, Diego Moral; Zenati, Marco A.; Riviere, Cameron N.

2012-01-01

HeartLander, a small mobile robot designed to provide treatments to the surface of the beating heart, overcomes a major difficulty of minimally invasive cardiac surgery, providing a stable operating platform. This is achieved inherently in the way the robot adheres to and crawls over the surface of the heart. This mode of operation does not require physiological motion compensation to provide this stable environment; however, modeling of physiological motion is advantageous in providing more accurate position estimation as well as synchronization of motion to the physiological cycles. The work presented uses an Extended Kalman Filter framework to estimate parameters of non-stationary Fourier series models of the motion of the heart due to the respiratory and cardiac cycles as well as the position of the robot as it moves over the surface of the heart. The proposed method is demonstrated in the laboratory with HeartLander operating on a physiological motion simulator. Improved performance is demonstrated in comparison to the filtering methods previously used with HeartLander. The use of detected physiological cycle phases to synchronize locomotion of HeartLander is also described. PMID:23066511

Position Estimation of an Epicardial Crawling Robot on the Beating Heart by Modeling of Physiological Motion.

PubMed

Wood, Nathan A; Del Agua, Diego Moral; Zenati, Marco A; Riviere, Cameron N

2011-12-05

HeartLander, a small mobile robot designed to provide treatments to the surface of the beating heart, overcomes a major difficulty of minimally invasive cardiac surgery, providing a stable operating platform. This is achieved inherently in the way the robot adheres to and crawls over the surface of the heart. This mode of operation does not require physiological motion compensation to provide this stable environment; however, modeling of physiological motion is advantageous in providing more accurate position estimation as well as synchronization of motion to the physiological cycles. The work presented uses an Extended Kalman Filter framework to estimate parameters of non-stationary Fourier series models of the motion of the heart due to the respiratory and cardiac cycles as well as the position of the robot as it moves over the surface of the heart. The proposed method is demonstrated in the laboratory with HeartLander operating on a physiological motion simulator. Improved performance is demonstrated in comparison to the filtering methods previously used with HeartLander. The use of detected physiological cycle phases to synchronize locomotion of HeartLander is also described.

Application of Cardiac Gating to Improve the Reproducibility of Intravoxel Incoherent Motion Measurements in the Head and Neck.

PubMed

Kang, Koung Mi; Choi, Seung Hong; Kim, Dong Eun; Yun, Tae Jin; Kim, Ji-Hoon; Sohn, Chul-Ho; Park, Sun-Won

2017-07-10

To prospectively evaluate whether cardiac gating can improve the reproducibility of intravoxel incoherent motion (IVIM) parameters in the head and neck, we performed IVIM diffusion-weighted imaging (DWI) using 4 b values (4b), 4 b values with cardiac gating (4b gating) and 17 b values (17b). We performed IVIM DWI twice per person on nine healthy volunteers using 4b, 4b gating and 17b and five patients with head and neck masses using 4b gating and 17b. The ADC, perfusion fraction (f), diffusion coefficient (D) and perfusion-related diffusion coefficient (D*) were calculated in the brain, masticator muscle, parotid gland, submandibular gland, tonsil and masses. Intraclass coefficient (ICC), Bland-Altman analysis (BAA) and coefficient of variation (CV) were used to assess short-term test-retest reproducibility. Kruskal-Wallis test and Mann-Whitney test were used to investigate whether 4b, 4b gating or 17b had significant influences on the parameters. For normal tissues and masses, ICC was excellent for all maps except the D* map. All parameters showed the lowest CV in the 4b gating. BAA also revealed the narrowest 95% limits of agreement using 4b gating for all parameters. In the subgroup analysis, almost all parameters in brain, muscle, parotid gland and submandibular gland showed the best reproducibility using 4b gating. In the muscle, parotid gland and submandibular gland, the values of ADC, f and D were not significantly different between among the three methods. 4b gating was more reproducible with respect to measurements of IVIM parameters in comparison with 4b or 17b.

Prognostic value of exercise echocardiography: validation of a new risk index combining echocardiographic, treadmill, and exercise electrocardiographic parameters.

PubMed

Mazur, Wojciech; Rivera, Jose M; Khoury, Alexander F; Basu, Abhijeet G; Perez-Verdia, Alejandro; Marks, Gary F; Chang, Su Min; Olmos, Leopoldo; Quiñones, Miguel A; Zoghbi, William A

2003-04-01

Exercise (Ex) echocardiography has been shown to have significant prognostic power, independent of other known predictors of risk from an Ex stress test. The purpose of this study was to evaluate a risk index, incorporating echocardiographic and conventional Ex variables, for a more comprehensive risk stratification and identification of a very low-risk group. Two consecutive, mutually exclusive populations referred for treadmill Ex echocardiography with the Bruce protocol were investigated: hypothesis-generating (388 patients; 268 males; age 55 +/- 13 years) and hypothesis-testing (105 patients; 61 males age: 54 +/- 14 years).Cardiac events included cardiac death, myocardial infarction, late revascularization (>90 days), hospital admission for unstable angina, and admission for heart failure. Mean follow-up in the hypothesis-generating population was 3.1 years. There were 38 cardiac events. Independent predictors of events by multivariate analysis were: Ex wall motion score index (odds ratio [OR] = 2.77/Unit; P <.001); ischemic S-T depression > or = 1 mm (OR = 2.84; P =.002); and treadmill time (OR = 0.87/min; P =.037). A risk index was generated on the basis of the multivariate Cox regression model as: risk index = 1.02 (Ex wall motion score index) + 1.04 (S-T change) - 0.14 (treadmill time). The validity of this index was tested in the hypothesis-testing population. Event rates at 3 years were lowest (0%) in the lower quartile of risk index (-1.22 to -0.47), highest (29.6%) in the upper quartile (+0.66 to +2.02), and intermediate (19.2% to 15.3%) in the intermediate quartiles. The OR of the risk index for predicting cardiac events was 2.94/Unit ([95% confidence interval: 1.4 to 6.2]; P =.0043). Echocardiographic and Ex parameters are independent powerful predictors of cardiac events after treadmill stress testing. A risk index can be derived with these parameters for a more comprehensive risk stratification with Ex echocardiography.

Moving Domain Computational Fluid Dynamics to Interface with an Embryonic Model of Cardiac Morphogenesis

PubMed Central

Lee, Juhyun; Moghadam, Mahdi Esmaily; Kung, Ethan; Cao, Hung; Beebe, Tyler; Miller, Yury; Roman, Beth L.; Lien, Ching-Ling; Chi, Neil C.; Marsden, Alison L.; Hsiai, Tzung K.

2013-01-01

Peristaltic contraction of the embryonic heart tube produces time- and spatial-varying wall shear stress (WSS) and pressure gradients (∇P) across the atrioventricular (AV) canal. Zebrafish (Danio rerio) are a genetically tractable system to investigate cardiac morphogenesis. The use of Tg(fli1a:EGFP)y1 transgenic embryos allowed for delineation and two-dimensional reconstruction of the endocardium. This time-varying wall motion was then prescribed in a two-dimensional moving domain computational fluid dynamics (CFD) model, providing new insights into spatial and temporal variations in WSS and ∇P during cardiac development. The CFD simulations were validated with particle image velocimetry (PIV) across the atrioventricular (AV) canal, revealing an increase in both velocities and heart rates, but a decrease in the duration of atrial systole from early to later stages. At 20-30 hours post fertilization (hpf), simulation results revealed bidirectional WSS across the AV canal in the heart tube in response to peristaltic motion of the wall. At 40-50 hpf, the tube structure undergoes cardiac looping, accompanied by a nearly 3-fold increase in WSS magnitude. At 110-120 hpf, distinct AV valve, atrium, ventricle, and bulbus arteriosus form, accompanied by incremental increases in both WSS magnitude and ∇P, but a decrease in bi-directional flow. Laminar flow develops across the AV canal at 20-30 hpf, and persists at 110-120 hpf. Reynolds numbers at the AV canal increase from 0.07±0.03 at 20-30 hpf to 0.23±0.07 at 110-120 hpf (p< 0.05, n=6), whereas Womersley numbers remain relatively unchanged from 0.11 to 0.13. Our moving domain simulations highlights hemodynamic changes in relation to cardiac morphogenesis; thereby, providing a 2-D quantitative approach to complement imaging analysis. PMID:24009714

Nonrigid registration-based coronary artery motion correction for cardiac computed tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhagalia, Roshni; Pack, Jed D.; Miller, James V.

2012-07-15

Purpose: X-ray computed tomography angiography (CTA) is the modality of choice to noninvasively monitor and diagnose heart disease with coronary artery health and stenosis detection being of particular interest. Reliable, clinically relevant coronary artery imaging mandates high spatiotemporal resolution. However, advances in intrinsic scanner spatial resolution (CT scanners are available which combine nearly 900 detector columns with focal spot oversampling) can be tempered by motion blurring, particularly in patients with unstable heartbeats. As a result, recently numerous methods have been devised to improve coronary CTA imaging. Solutions involving hardware, multisector algorithms, or {beta}-blockers are limited by cost, oversimplifying assumptions aboutmore » cardiac motion, and populations showing contraindications to drugs, respectively. This work introduces an inexpensive algorithmic solution that retrospectively improves the temporal resolution of coronary CTA without significantly affecting spatial resolution. Methods: Given the goal of ruling out coronary stenosis, the method focuses on 'deblurring' the coronary arteries. The approach makes no assumptions about cardiac motion, can be used on exams acquired at high heart rates (even over 75 beats/min), and draws on a fast and accurate three-dimensional (3D) nonrigid bidirectional labeled point matching approach to estimate the trajectories of the coronary arteries during image acquisition. Motion compensation is achieved by employing a 3D warping of a series of partial reconstructions based on the estimated motion fields. Each of these partial reconstructions is created from data acquired over a short time interval. For brevity, the algorithm 'Subphasic Warp and Add' (SWA) reconstruction. Results: The performance of the new motion estimation-compensation approach was evaluated by a systematic observer study conducted using nine human cardiac CTA exams acquired over a range of average heart rates between 68 and 86 beats/min. Algorithm performance was based-lined against exams reconstructed using standard filtered-backprojection (FBP). The study was performed by three experienced reviewers using the American Heart Association's 15-segment model. All vessel segments were evaluated to quantify their viability to allow a clinical diagnosis before and after motion estimation-compensation using SWA. To the best of the authors' knowledge this is the first such observer study to show that an image processing-based software approach can improve the clinical diagnostic value of CTA for coronary artery evaluation. Conclusions: Results from the observer study show that the SWA method described here can dramatically reduce coronary artery motion and preserve real pathology, without affecting spatial resolution. In particular, the method successfully mitigated motion artifacts in 75% of all initially nondiagnostic coronary artery segments, and in over 45% of the cases this improvement was enough to make a previously nondiagnostic vessel segment clinically diagnostic.« less

Residual motion compensation in ECG-gated interventional cardiac vasculature reconstruction

NASA Astrophysics Data System (ADS)

Schwemmer, C.; Rohkohl, C.; Lauritsch, G.; Müller, K.; Hornegger, J.

2013-06-01

Three-dimensional reconstruction of cardiac vasculature from angiographic C-arm CT (rotational angiography) data is a major challenge. Motion artefacts corrupt image quality, reducing usability for diagnosis and guidance. Many state-of-the-art approaches depend on retrospective ECG-gating of projection data for image reconstruction. A trade-off has to be made regarding the size of the ECG-gating window. A large temporal window is desirable to avoid undersampling. However, residual motion will occur in a large window, causing motion artefacts. We present an algorithm to correct for residual motion. Our approach is based on a deformable 2D-2D registration between the forward projection of an initial, ECG-gated reconstruction, and the original projection data. The approach is fully automatic and does not require any complex segmentation of vasculature, or landmarks. The estimated motion is compensated for during the backprojection step of a subsequent reconstruction. We evaluated the method using the publicly available CAVAREV platform and on six human clinical datasets. We found a better visibility of structure, reduced motion artefacts, and increased sharpness of the vessels in the compensated reconstructions compared to the initial reconstructions. At the time of writing, our algorithm outperforms the leading result of the CAVAREV ranking list. For the clinical datasets, we found an average reduction of motion artefacts by 13 ± 6%. Vessel sharpness was improved by 25 ± 12% on average.

Cardiac imaging with multi-sector data acquisition in volumetric CT: variation of effective temporal resolution and its potential clinical consequences

NASA Astrophysics Data System (ADS)

Tang, Xiangyang; Hsieh, Jiang; Taha, Basel H.; Vass, Melissa L.; Seamans, John L.; Okerlund, Darin R.

2009-02-01

With increasing longitudinal detector dimension available in diagnostic volumetric CT, step-and-shoot scan is becoming popular for cardiac imaging. In comparison to helical scan, step-and-shoot scan decouples patient table movement from cardiac gating/triggering, which facilitates the cardiac imaging via multi-sector data acquisition, as well as the administration of inter-cycle heart beat variation (arrhythmia) and radiation dose efficiency. Ideally, a multi-sector data acquisition can improve temporal resolution at a factor the same as the number of sectors (best scenario). In reality, however, the effective temporal resolution is jointly determined by gantry rotation speed and patient heart beat rate, which may significantly lower than the ideal or no improvement (worst scenario). Hence, it is clinically relevant to investigate the behavior of effective temporal resolution in cardiac imaging with multi-sector data acquisition. In this study, a 5-second cine scan of a porcine heart, which cascades 6 porcine cardiac cycles, is acquired. In addition to theoretical analysis and motion phantom study, the clinical consequences due to the effective temporal resolution variation are evaluated qualitative or quantitatively. By employing a 2-sector image reconstruction strategy, a total of 15 (the permutation of P(6, 2)) cases between the best and worst scenarios are studied, providing informative guidance for the design and optimization of CT cardiac imaging in volumetric CT with multi-sector data acquisition.

Distribution of late gadolinium enhancement in various types of cardiomyopathies: Significance in differential diagnosis, clinical features and prognosis

PubMed Central

Satoh, Hiroshi; Sano, Makoto; Suwa, Kenichiro; Saitoh, Takeji; Nobuhara, Mamoru; Saotome, Masao; Urushida, Tsuyoshi; Katoh, Hideki; Hayashi, Hideharu

2014-01-01

The recent development of cardiac magnetic resonance (CMR) techniques has allowed detailed analyses of cardiac function and tissue characterization with high spatial resolution. We review characteristic CMR features in ischemic and non-ischemic cardiomyopathies (ICM and NICM), especially in terms of the location and distribution of late gadolinium enhancement (LGE). CMR in ICM shows segmental wall motion abnormalities or wall thinning in a particular coronary arterial territory, and the subendocardial or transmural LGE. LGE in NICM generally does not correspond to any particular coronary artery distribution and is located mostly in the mid-wall to subepicardial layer. The analysis of LGE distribution is valuable to differentiate NICM with diffusely impaired systolic function, including dilated cardiomyopathy, end-stage hypertrophic cardiomyopathy (HCM), cardiac sarcoidosis, and myocarditis, and those with diffuse left ventricular (LV) hypertrophy including HCM, cardiac amyloidosis and Anderson-Fabry disease. A transient low signal intensity LGE in regions of severe LV dysfunction is a particular feature of stress cardiomyopathy. In arrhythmogenic right ventricular cardiomyopathy/dysplasia, an enhancement of right ventricular (RV) wall with functional and morphological changes of RV becomes apparent. Finally, the analyses of LGE distribution have potentials to predict cardiac outcomes and response to treatments. PMID:25068019

An update on technical and methodological aspects for cardiac PET applications.

PubMed

Presotto, Luca; Busnardo, Elena; Gianolli, Luigi; Bettinardi, Valentino

2016-12-01

Positron emission tomography (PET) is indicated for a large number of cardiac diseases: perfusion and viability studies are commonly used to evaluate coronary artery disease; PET can also be used to assess sarcoidosis and endocarditis, as well as to investigate amyloidosis. Furthermore, a hot topic for research is plaque characterization. Most of these studies are technically very challenging. High count rates and short acquisition times characterize perfusion scans while very small targets have to be imaged in inflammation/infection and plaques examinations. Furthermore, cardiac PET suffers from respiratory and cardiac motion blur. Each type of studies has specific requirements from the technical and methodological point of view, thus PET systems with overall high performances are required. Furthermore, in the era of hybrid PET/computed tomography (CT) and PET/Magnetic Resonance Imaging (MRI) systems, the combination of complementary functional and anatomical information can be used to improve diagnosis and prognosis. Moreover, PET images can be qualitatively and quantitatively improved exploiting information from the other modality, using advanced algorithms. In this review we will report the latest technological and methodological innovations for PET cardiac applications, with particular reference to the state of the art of the hybrid PET/CT and PET/MRI. We will also report the most recent advancements in software, from reconstruction algorithms to image processing and analysis programs.

Building and using a statistical 3D motion atlas for analyzing myocardial contraction in MRI

NASA Astrophysics Data System (ADS)

Rougon, Nicolas F.; Petitjean, Caroline; Preteux, Francoise J.

2004-05-01

We address the issue of modeling and quantifying myocardial contraction from 4D MR sequences, and present an unsupervised approach for building and using a statistical 3D motion atlas for the normal heart. This approach relies on a state-of-the-art variational non rigid registration (NRR) technique using generalized information measures, which allows for robust intra-subject motion estimation and inter-subject anatomical alignment. The atlas is built from a collection of jointly acquired tagged and cine MR exams in short- and long-axis views. Subject-specific non parametric motion estimates are first obtained by incremental NRR of tagged images onto the end-diastolic (ED) frame. Individual motion data are then transformed into the coordinate system of a reference subject using subject-to-reference mappings derived by NRR of cine ED images. Finally, principal component analysis of aligned motion data is performed for each cardiac phase, yielding a mean model and a set of eigenfields encoding kinematic ariability. The latter define an organ-dedicated hierarchical motion basis which enables parametric motion measurement from arbitrary tagged MR exams. To this end, the atlas is transformed into subject coordinates by reference-to-subject NRR of ED cine frames. Atlas-based motion estimation is then achieved by parametric NRR of tagged images onto the ED frame, yielding a compact description of myocardial contraction during diastole.

Image reconstruction in higher dimensions: myocardial perfusion imaging of tracer dynamics with cardiac motion due to deformation and respiration

DOE PAGES

Shrestha, Uttam M.; Seo, Youngho; Botvinick, Elias H.; ...

2015-10-09

Myocardial perfusion imaging (MPI) using slow rotating large field of view cameras requires spatiotemporal reconstruction of dynamically acquired data to capture the time variation of the radiotracer concentration. In vivo, MPI contains additional degrees of freedom involving unavoidable motion of the heart due to quasiperiodic beating and the effects of respiration, which can severely degrade the quality of the images. This work develops a technique for a single photon emission computed tomography (SPECT) that reconstructs the distribution of the radiotracer concentration in the myocardium using a tensor product of different sets of basis functions that approximately describe the spatiotemporal variationmore » of the radiotracer concentration and the motion of the heart. In this study the temporal B-spline basis functions are chosen to reflect the dynamics of the radiotracer, while the intrinsic deformation and the extrinsic motion of the heart are described by a product of a discrete set of Gaussian basis functions. Reconstruction results are presented showing the dynamics of the tracer in the myocardium as it deforms due to cardiac beating, and is displaced due to respiratory motion. We find these results are compared with the conventional 4D-spatiotemporal reconstruction method that models only the temporal changes of the tracer activity. The higher dimensional reconstruction method proposed here improves bias, yet the signal-to-noise ratio (SNR) decreases slightly due to redistribution of the counts over the cardiac-respiratory gates. Finally, there is a trade-off between the number of gates and the number of projections per gate to achieve high contrast images.« less

Image reconstruction in higher dimensions: myocardial perfusion imaging of tracer dynamics with cardiac motion due to deformation and respiration

NASA Astrophysics Data System (ADS)

Shrestha, Uttam M.; Seo, Youngho; Botvinick, Elias H.; Gullberg, Grant T.

2015-11-01

Myocardial perfusion imaging (MPI) using slow rotating large field of view cameras requires spatiotemporal reconstruction of dynamically acquired data to capture the time variation of the radiotracer concentration. In vivo, MPI contains additional degrees of freedom involving unavoidable motion of the heart due to quasiperiodic beating and the effects of respiration, which can severely degrade the quality of the images. This work develops a technique for a single photon emission computed tomography (SPECT) that reconstructs the distribution of the radiotracer concentration in the myocardium using a tensor product of different sets of basis functions that approximately describe the spatiotemporal variation of the radiotracer concentration and the motion of the heart. In this study the temporal B-spline basis functions are chosen to reflect the dynamics of the radiotracer, while the intrinsic deformation and the extrinsic motion of the heart are described by a product of a discrete set of Gaussian basis functions. Reconstruction results are presented showing the dynamics of the tracer in the myocardium as it deforms due to cardiac beating, and is displaced due to respiratory motion. These results are compared with the conventional 4D-spatiotemporal reconstruction method that models only the temporal changes of the tracer activity. The higher dimensional reconstruction method proposed here improves bias, yet the signal-to-noise ratio (SNR) decreases slightly due to redistribution of the counts over the cardiac-respiratory gates. Additionally, there is a trade-off between the number of gates and the number of projections per gate to achieve high contrast images.

Image reconstruction in higher dimensions: myocardial perfusion imaging of tracer dynamics with cardiac motion due to deformation and respiration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shrestha, Uttam M.; Seo, Youngho; Botvinick, Elias H.

Myocardial perfusion imaging (MPI) using slow rotating large field of view cameras requires spatiotemporal reconstruction of dynamically acquired data to capture the time variation of the radiotracer concentration. In vivo, MPI contains additional degrees of freedom involving unavoidable motion of the heart due to quasiperiodic beating and the effects of respiration, which can severely degrade the quality of the images. This work develops a technique for a single photon emission computed tomography (SPECT) that reconstructs the distribution of the radiotracer concentration in the myocardium using a tensor product of different sets of basis functions that approximately describe the spatiotemporal variationmore » of the radiotracer concentration and the motion of the heart. In this study the temporal B-spline basis functions are chosen to reflect the dynamics of the radiotracer, while the intrinsic deformation and the extrinsic motion of the heart are described by a product of a discrete set of Gaussian basis functions. Reconstruction results are presented showing the dynamics of the tracer in the myocardium as it deforms due to cardiac beating, and is displaced due to respiratory motion. We find these results are compared with the conventional 4D-spatiotemporal reconstruction method that models only the temporal changes of the tracer activity. The higher dimensional reconstruction method proposed here improves bias, yet the signal-to-noise ratio (SNR) decreases slightly due to redistribution of the counts over the cardiac-respiratory gates. Finally, there is a trade-off between the number of gates and the number of projections per gate to achieve high contrast images.« less

Image reconstruction in higher dimensions: myocardial perfusion imaging of tracer dynamics with cardiac motion due to deformation and respiration.

PubMed

Shrestha, Uttam M; Seo, Youngho; Botvinick, Elias H; Gullberg, Grant T

2015-11-07

Myocardial perfusion imaging (MPI) using slow rotating large field of view cameras requires spatiotemporal reconstruction of dynamically acquired data to capture the time variation of the radiotracer concentration. In vivo, MPI contains additional degrees of freedom involving unavoidable motion of the heart due to quasiperiodic beating and the effects of respiration, which can severely degrade the quality of the images. This work develops a technique for a single photon emission computed tomography (SPECT) that reconstructs the distribution of the radiotracer concentration in the myocardium using a tensor product of different sets of basis functions that approximately describe the spatiotemporal variation of the radiotracer concentration and the motion of the heart. In this study the temporal B-spline basis functions are chosen to reflect the dynamics of the radiotracer, while the intrinsic deformation and the extrinsic motion of the heart are described by a product of a discrete set of Gaussian basis functions. Reconstruction results are presented showing the dynamics of the tracer in the myocardium as it deforms due to cardiac beating, and is displaced due to respiratory motion. These results are compared with the conventional 4D-spatiotemporal reconstruction method that models only the temporal changes of the tracer activity. The higher dimensional reconstruction method proposed here improves bias, yet the signal-to-noise ratio (SNR) decreases slightly due to redistribution of the counts over the cardiac-respiratory gates. Additionally, there is a trade-off between the number of gates and the number of projections per gate to achieve high contrast images.

A method to synchronize signals from multiple patient monitoring devices through a single input channel for inclusion in list-mode acquisitions

DOE Office of Scientific and Technical Information (OSTI.GOV)

O’Connor, J. Michael; Pretorius, P. Hendrik; Johnson, Karen

2013-12-15

Purpose: This technical note documents a method that the authors developed for combining a signal to synchronize a patient-monitoring device with a second physiological signal for inclusion into list-mode acquisition. Our specific application requires synchronizing an external patient motion-tracking system with a medical imaging system by multiplexing the tracking input with the ECG input. The authors believe that their methodology can be adapted for use in a variety of medical imaging modalities including single photon emission computed tomography (SPECT) and positron emission tomography (PET). Methods: The authors insert a unique pulse sequence into a single physiological input channel. This sequencemore » is then recorded in the list-mode acquisition along with the R-wave pulse used for ECG gating. The specific form of our pulse sequence allows for recognition of the time point being synchronized even when portions of the pulse sequence are lost due to collisions with R-wave pulses. This was achieved by altering our software used in binning the list-mode data to recognize even a portion of our pulse sequence. Limitations on heart rates at which our pulse sequence could be reliably detected were investigated by simulating the mixing of the two signals as a function of heart rate and time point during the cardiac cycle at which our pulse sequence is mixed with the cardiac signal. Results: The authors have successfully achieved accurate temporal synchronization of our motion-tracking system with acquisition of SPECT projections used in 17 recent clinical research cases. In our simulation analysis the authors determined that synchronization to enable compensation for body and respiratory motion could be achieved for heart rates up to 125 beats-per-minute (bpm). Conclusions: Synchronization of list-mode acquisition with external patient monitoring devices such as those employed in motion-tracking can reliably be achieved using a simple method that can be implemented using minimal external hardware and software modification through a single input channel, while still recording cardiac gating signals.« less

Image quality improvement in MDCT cardiac imaging via SMART-RECON method

NASA Astrophysics Data System (ADS)

Li, Yinsheng; Cao, Ximiao; Xing, Zhanfeng; Sun, Xuguang; Hsieh, Jiang; Chen, Guang-Hong

2017-03-01

Coronary CT angiography (CCTA) is a challenging imaging task currently limited by the achievable temporal resolution of modern Multi-Detector CT (MDCT) scanners. In this paper, the recently proposed SMARTRECON method has been applied in MDCT-based CCTA imaging to improve the image quality without any prior knowledge of cardiac motion. After the prospective ECG-gated data acquisition from a short-scan angular span, the acquired data were sorted into several sub-sectors of view angles; each corresponds to a 1/4th of the short-scan angular range. Information of the cardiac motion was thus encoded into the data in each view angle sub-sector. The SMART-RECON algorithm was then applied to jointly reconstruct several image volumes, each of which is temporally consistent with the data acquired in the corresponding view angle sub-sector. Extensive numerical simulations were performed to validate the proposed technique and investigate the performance dependence.

Regional Pericarditis Status Post Cardiac Ablation: A Case Report

PubMed Central

Orme, Joseph; Eddin, Moneer; Loli, Akil

2014-01-01

Context: Regional pericarditis is elusive and difficult to diagnosis. Healthcare providers should be familiar with post-cardiac ablation complications as this procedure is now widespread and frequently performed. The management of regional pericarditis differs greatly from that of acute myocardial infarction. Case report: A 52 year-old male underwent atrial fibrillation ablation and developed severe mid-sternal chest pain the following day with electrocardiographic findings suggestive of acute myocardial infarction, and underwent coronary angiography, a left ventriculogram, and 2D transthoracic echocardiogram, all of which were unremarkable without evidence of obstructive coronary disease, wall motion abnormalities, or pericardial effusions. Ultimately, the patient was diagnosed with regional pericarditis. After diagnosis, the patient's presenting symptoms resolved with treatment including nonsteroidal anti-inflammatory agents and colchicine. Conclusion: This is the first reported case study of regional pericarditis status post cardiac ablation. Electrocardiographic findings were classic for an acute myocardial infarction; however, coronary angiography and left ventriculogram demonstrated no acute coronary occlusion or ventricular wall motion abnormalities. Healthcare professionals must remember that the electrocardiographic findings in pericarditis are not always classic and that pericarditis can occur status post cardiac ablation. PMID:25317395

Regional pericarditis status post cardiac ablation: a case report.

PubMed

Orme, Joseph; Eddin, Moneer; Loli, Akil

2014-09-01

Regional pericarditis is elusive and difficult to diagnosis. Healthcare providers should be familiar with post-cardiac ablation complications as this procedure is now widespread and frequently performed. The management of regional pericarditis differs greatly from that of acute myocardial infarction. A 52 year-old male underwent atrial fibrillation ablation and developed severe mid-sternal chest pain the following day with electrocardiographic findings suggestive of acute myocardial infarction, and underwent coronary angiography, a left ventriculogram, and 2D transthoracic echocardiogram, all of which were unremarkable without evidence of obstructive coronary disease, wall motion abnormalities, or pericardial effusions. Ultimately, the patient was diagnosed with regional pericarditis. After diagnosis, the patient's presenting symptoms resolved with treatment including nonsteroidal anti-inflammatory agents and colchicine. This is the first reported case study of regional pericarditis status post cardiac ablation. Electrocardiographic findings were classic for an acute myocardial infarction; however, coronary angiography and left ventriculogram demonstrated no acute coronary occlusion or ventricular wall motion abnormalities. Healthcare professionals must remember that the electrocardiographic findings in pericarditis are not always classic and that pericarditis can occur status post cardiac ablation.

MRXCAT: Realistic numerical phantoms for cardiovascular magnetic resonance

PubMed Central

2014-01-01

Background Computer simulations are important for validating novel image acquisition and reconstruction strategies. In cardiovascular magnetic resonance (CMR), numerical simulations need to combine anatomical information and the effects of cardiac and/or respiratory motion. To this end, a framework for realistic CMR simulations is proposed and its use for image reconstruction from undersampled data is demonstrated. Methods The extended Cardiac-Torso (XCAT) anatomical phantom framework with various motion options was used as a basis for the numerical phantoms. Different tissue, dynamic contrast and signal models, multiple receiver coils and noise are simulated. Arbitrary trajectories and undersampled acquisition can be selected. The utility of the framework is demonstrated for accelerated cine and first-pass myocardial perfusion imaging using k-t PCA and k-t SPARSE. Results MRXCAT phantoms allow for realistic simulation of CMR including optional cardiac and respiratory motion. Example reconstructions from simulated undersampled k-t parallel imaging demonstrate the feasibility of simulated acquisition and reconstruction using the presented framework. Myocardial blood flow assessment from simulated myocardial perfusion images highlights the suitability of MRXCAT for quantitative post-processing simulation. Conclusion The proposed MRXCAT phantom framework enables versatile and realistic simulations of CMR including breathhold and free-breathing acquisitions. PMID:25204441

A robust and accurate center-frequency estimation (RACE) algorithm for improving motion estimation performance of SinMod on tagged cardiac MR images without known tagging parameters.

PubMed

Liu, Hong; Wang, Jie; Xu, Xiangyang; Song, Enmin; Wang, Qian; Jin, Renchao; Hung, Chih-Cheng; Fei, Baowei

2014-11-01

A robust and accurate center-frequency (CF) estimation (RACE) algorithm for improving the performance of the local sine-wave modeling (SinMod) method, which is a good motion estimation method for tagged cardiac magnetic resonance (MR) images, is proposed in this study. The RACE algorithm can automatically, effectively and efficiently produce a very appropriate CF estimate for the SinMod method, under the circumstance that the specified tagging parameters are unknown, on account of the following two key techniques: (1) the well-known mean-shift algorithm, which can provide accurate and rapid CF estimation; and (2) an original two-direction-combination strategy, which can further enhance the accuracy and robustness of CF estimation. Some other available CF estimation algorithms are brought out for comparison. Several validation approaches that can work on the real data without ground truths are specially designed. Experimental results on human body in vivo cardiac data demonstrate the significance of accurate CF estimation for SinMod, and validate the effectiveness of RACE in facilitating the motion estimation performance of SinMod. Copyright © 2014 Elsevier Inc. All rights reserved.

Spillover Compensation in the Presence of Respiratory Motion Embedded in SPECT Perfusion Data

NASA Astrophysics Data System (ADS)

Pretorius, P. Hendrik; King, Michael A.

2008-02-01

Spillover from adjacent significant accumulations of extra-cardiac activity decreases diagnostic accuracy of SPECT perfusion imaging in especially the inferior/septal cardiac region. One method of compensating for the spillover at some location outside of a structure is to estimate it as the counts blurred into this location when a template (3D model) of the structure undergoes simulated imaging followed by reconstruction. The objective of this study was to determine what impact uncorrected respiratory motion has on such spillover compensation of extra-cardiac activity in the right coronary artery (RCA) territory, and if it is possible to use manual segmentation to define the extra-cardiac activity template(s) used in spillover correction. Two separate MCAT phantoms (1283 matrices) were simulated to represent the source and attenuation distributions of patients with and without respiratory motion. For each phantom the heart was modeled: 1) with a normal perfusion pattern and 2) with an RCA defect equal to 50% of the normal myocardium count level. After Monte Carlo simulation of 64times64times120 projections with appropriate noise, data were reconstructed using the rescaled block iterative (RBI) algorithm with 30 subsets and 5 iterations with compensation for attenuation, scatter and resolution. A 3D Gaussian post-filter with a sigma of 0.476 cm was used to suppress noise. Manual segmentation of the liver in filtered emission slices was used to create 3D binary templates. The true liver distribution (with and without respiratory motion included) was also used as binary templates. These templates were projected using a ray-driven projector simulating the imaging system with the exclusion of Compton scatter and reconstructed using the same protocol as for the emission data, excluding scatter compensation. Reconstructed templates were scaled using reconstructed emission count levels from the liver, and spillover subtracted outside the template. It was evident from the polar maps that the manually segmented template reconstructions were unable to remove all the spillover originating in the liver from the inferior wall. This was especially noticeable when a perfusion defect is present. Templates based on the true liver distribution appreciably improved spillover correction. Thus the emerging combined SPECT/CT technology may play a vital role in identifying and segmenting extra-cardiac structures more reliably thereby facilitating spillover correction. This study also indicates that compensation for respiratory motion might play an important role in spillover compensation.

Three-dimensional self-gated cardiac MR imaging for the evaluation of myocardial infarction in mouse model on a 3T clinical MR system.

PubMed

Zhang, Xiaoyong; Qiu, Bensheng; Wei, Zijun; Yan, Fei; Shi, Caiyun; Su, Shi; Liu, Xin; Ji, Jim X; Xie, Guoxi

2017-01-01

To develop and assess a three-dimensional (3D) self-gated technique for the evaluation of myocardial infarction (MI) in mouse model without the use of external electrocardiogram (ECG) trigger and respiratory motion sensor on a 3T clinical MR system. A 3D T1-weighted GRE sequence with stack-of-stars sampling trajectories was developed and performed on six mice with MIs that were injected with a gadolinium-based contrast agent at a 3T clinical MR system. Respiratory and cardiac self-gating signals were derived from the Cartesian mapping of the k-space center along the partition encoding direction by bandpass filtering in image domain. The data were then realigned according to the predetermined self-gating signals for the following image reconstruction. In order to accelerate the data acquisition, image reconstruction was based on compressed sensing (CS) theory by exploiting temporal sparsity of the reconstructed images. In addition, images were also reconstructed from the same realigned data by conventional regridding method for demonstrating the advantageous of the proposed reconstruction method. Furthermore, the accuracy of detecting MI by the proposed method was assessed using histological analysis as the standard reference. Linear regression and Bland-Altman analysis were used to assess the agreement between the proposed method and the histological analysis. Compared to the conventional regridding method, the proposed CS method reconstructed images with much less streaking artifact, as well as a better contrast-to-noise ratio (CNR) between the blood and myocardium (4.1 ± 2.1 vs. 2.9 ± 1.1, p = 0.031). Linear regression and Bland-Altman analysis demonstrated that excellent correlation was obtained between infarct sizes derived from the proposed method and histology analysis. A 3D T1-weighted self-gating technique for mouse cardiac imaging was developed, which has potential for accurately evaluating MIs in mice at 3T clinical MR system without the use of external ECG trigger and respiratory motion sensor.

Utility of Deep Inspiration Breath Hold for Left-Sided Breast Radiation Therapy in Preventing Early Cardiac Perfusion Defects: A Prospective Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zagar, Timothy M., E-mail: zagar@med.unc.edu; Kaidar-Person, Orit; Tang, Xiaoli

Purpose: To evaluate early cardiac single photon computed tomography (SPECT) findings after left breast/chest wall postoperative radiation therapy (RT) in the setting of deep inspiration breath hold (DIBH). Methods and Materials: We performed a prospective single-institution single-arm study of patients who were planned for tangential RT with DIBH to the left breast/chest wall (± internal mammary nodes). The DIBH was done by use of a controlled surface monitoring technique (AlignRT, Vision RT Ltd, London, UK). The RT was given with tangential fields and a heart block. Radiation-induced cardiac perfusion and wall motion changes were assessed by pre-RT and 6-month post-RTmore » SPECT scans. A cumulative SPECT summed-rest score was used to quantify perfusion in predefined left ventricle segments. The incidence of wall motion abnormalities was assessed in each of these same segments. Results: A total of 20 patients with normal pre-RT scans were studied; their median age was 56 years (range, 39-72 years). Seven (35%) patients also received irradiation to the left internal mammary chain, and 5 (25%) received an additional RT field to supraclavicular nodes. The median heart dose was 94 cGy (range, 56-200 cGy), and the median V25{sub Gy} was zero (range, 0-0.1). None of the patients had post-RT perfusion or wall motion abnormalities. Conclusions: Our results suggest that DIBH and conformal cardiac blocking for patients receiving tangential RT for left-sided breast cancer is an effective means to avoid early RT-associated cardiac perfusion defects.« less

Cardiac gating with a pulse oximeter for dual-energy imaging

NASA Astrophysics Data System (ADS)

Shkumat, N. A.; Siewerdsen, J. H.; Dhanantwari, A. C.; Williams, D. B.; Paul, N. S.; Yorkston, J.; Van Metter, R.

2008-11-01

The development and evaluation of a prototype cardiac gating system for double-shot dual-energy (DE) imaging is described. By acquiring both low- and high-kVp images during the resting phase of the cardiac cycle (diastole), heart misalignment between images can be reduced, thereby decreasing the magnitude of cardiac motion artifacts. For this initial implementation, a fingertip pulse oximeter was employed to measure the peripheral pulse waveform ('plethysmogram'), offering potential logistic, cost and workflow advantages compared to an electrocardiogram. A gating method was developed that accommodates temporal delays due to physiological pulse propagation, oximeter waveform processing and the imaging system (software, filter-wheel, anti-scatter Bucky-grid and flat-panel detector). Modeling the diastolic period allowed the calculation of an implemented delay, timp, required to trigger correctly during diastole at any patient heart rate (HR). The model suggests a triggering scheme characterized by two HR regimes, separated by a threshold, HRthresh. For rates at or below HRthresh, sufficient time exists to expose on the same heartbeat as the plethysmogram pulse [timp(HR) = 0]. Above HRthresh, a characteristic timp(HR) delays exposure to the subsequent heartbeat, accounting for all fixed and variable system delays. Performance was evaluated in terms of accuracy and precision of diastole-trigger coincidence and quantitative evaluation of artifact severity in gated and ungated DE images. Initial implementation indicated 85% accuracy in diastole-trigger coincidence. Through the identification of an improved HR estimation method (modified temporal smoothing of the oximeter waveform), trigger accuracy of 100% could be achieved with improved precision. To quantify the effect of the gating system on DE image quality, human observer tests were conducted to measure the magnitude of cardiac artifact under conditions of successful and unsuccessful diastolic gating. Six observers independently measured the artifact in 111 patient DE images. The data indicate that successful diastolic gating results in a statistically significant reduction (p < 0.001) in the magnitude of cardiac motion artifact, with residual artifact attributed primarily to gross patient motion.

ADAPTIVE REAL-TIME CARDIAC MRI USING PARADISE: VALIDATION BY THE PHYSIOLOGICALLY IMPROVED NCAT PHANTOM

PubMed Central

Sharif, Behzad; Bresler, Yoram

2013-01-01

Patient-Adaptive Reconstruction and Acquisition Dynamic Imaging with Sensitivity Encoding (PARADISE) is a dynamic MR imaging scheme that optimally combines parallel imaging and model-based adaptive acquisition. In this work, we propose the application of PARADISE to real-time cardiac MRI. We introduce a physiologically improved version of a realistic four-dimensional cardiac-torso (NCAT) phantom, which incorporates natural beat-to-beat heart rate and motion variations. Cardiac cine imaging using PARADISE is simulated and its performance is analyzed by virtue of the improved phantom. Results verify the effectiveness of PARADISE for high resolution un-gated real-time cardiac MRI and its superiority over conventional acquisition methods. PMID:24398475

Respiratory motion estimation in x-ray angiography for improved guidance during coronary interventions

NASA Astrophysics Data System (ADS)

Baka, N.; Lelieveldt, B. P. F.; Schultz, C.; Niessen, W.; van Walsum, T.

2015-05-01

During percutaneous coronary interventions (PCI) catheters and arteries are visualized by x-ray angiography (XA) sequences, using brief contrast injections to show the coronary arteries. If we could continue visualizing the coronary arteries after the contrast agent passed (thus in non-contrast XA frames), we could potentially lower contrast use, which is advantageous due to the toxicity of the contrast agent. This paper explores the possibility of such visualization in mono-plane XA acquisitions with a special focus on respiratory based coronary artery motion estimation. We use the patient specific coronary artery centerlines from pre-interventional 3D CTA images to project on the XA sequence for artery visualization. To achieve this, a framework for registering the 3D centerlines with the mono-plane 2D + time XA sequences is presented. During the registration the patient specific cardiac and respiratory motion is learned. We investigate several respiratory motion estimation strategies with respect to accuracy, plausibility and ease of use for motion prediction in XA frames with and without contrast. The investigated strategies include diaphragm motion based prediction, and respiratory motion extraction from the guiding catheter tip motion. We furthermore compare translational and rigid respiratory based heart motion. We validated the accuracy of the 2D/3D registration and the respiratory and cardiac motion estimations on XA sequences of 12 interventions. The diaphragm based motion model and the catheter tip derived motion achieved 1.58 mm and 1.83 mm median 2D accuracy, respectively. On a subset of four interventions we evaluated the artery visualization accuracy for non-contrast cases. Both diaphragm, and catheter tip based prediction performed similarly, with about half of the cases providing satisfactory accuracy (median error < 2 mm).

A net-shaped multicellular formation facilitates the maturation of hPSC-derived cardiomyocytes through mechanical and electrophysiological stimuli

PubMed Central

Liu, Taoyan; Huang, Chengwu; Li, Hongxia; Wu, Fujian; Luo, Jianwen; Lu, Wenjing

2018-01-01

The use of human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) is limited in drug discovery and cardiac disease mechanism studies due to cell immaturity. Although many approaches have been reported to improve the maturation of hiPSC-CMs, the elucidation of the process of maturation is crucial. We applied a small-molecule-based differentiation method to generate cardiomyocytes (CMs) with multiple aggregation forms. The motion analysis revealed significant physical differences in the differently shaped CMs, and the net-shaped CMs had larger motion amplitudes and faster velocities than the sheet-shaped CMs. The net-shaped CMs displayed accelerated maturation at the transcriptional level and were more similar to CMs with a prolonged culture time (30 days) than to sheet-d15. Ion channel genes and gap junction proteins were up-regulated in net-shaped CMs, indicating that robust contraction was coupled with enhanced ion channel and connexin expression. The net-shaped CMs also displayed improved myofibril ultrastructure under transmission electron microscopy. In conclusion, different multicellular hPSC-CM structures, such as the net-shaped pattern, are formed using the conditioned induction method, providing a useful tool to improve cardiac maturation. PMID:29661985

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dasari, Paul K. R.; Shazeeb, Mohammed Salman; Könik, Arda

Purpose: Binning list-mode acquisitions as a function of a surrogate signal related to respiration has been employed to reduce the impact of respiratory motion on image quality in cardiac emission tomography (SPECT and PET). Inherent in amplitude binning is the assumption that there is a monotonic relationship between the amplitude of the surrogate signal and respiratory motion of the heart. This assumption is not valid in the presence of hysteresis when heart motion exhibits a different relationship with the surrogate during inspiration and expiration. The purpose of this study was to investigate the novel approach of using the Bouc–Wen (BW)more » model to provide a signal accounting for hysteresis when binning list-mode data with the goal of thereby improving motion correction. The study is based on the authors’ previous observations that hysteresis between chest and abdomen markers was indicative of hysteresis between abdomen markers and the internal motion of the heart. Methods: In 19 healthy volunteers, they determined the internal motion of the heart and diaphragm in the superior–inferior direction during free breathing using MRI navigators. A visual tracking system (VTS) synchronized with MRI acquisition tracked the anterior–posterior motions of external markers placed on the chest and abdomen. These data were employed to develop and test the Bouc–Wen model by inputting the VTS derived chest and abdomen motions into it and using the resulting output signals as surrogates for cardiac motion. The data of the volunteers were divided into training and testing sets. The training set was used to obtain initial values for the model parameters for all of the volunteers in the set, and for set members based on whether they were or were not classified as exhibiting hysteresis using a metric derived from the markers. These initial parameters were then employed with the testing set to estimate output signals. Pearson’s linear correlation coefficient between the abdomen, chest, average of chest and abdomen markers, and Bouc–Wen derived signals versus the true internal motion of the heart from MRI was used to judge the signals match to the heart motion. Results: The results show that the Bouc–Wen model generated signals demonstrated strong correlation with the heart motion. This correlation was slightly larger on average than that of the external surrogate signals derived from the abdomen marker, and average of the abdomen and chest markers, but was not statistically significantly different from them. Conclusions: The results suggest that the proposed model has the potential to be a unified framework for modeling hysteresis in respiratory motion in cardiac perfusion studies and beyond.« less

Intraventricular flow alterations due to dyssynchronous wall motion

NASA Astrophysics Data System (ADS)

Pope, Audrey M.; Lai, Hong Kuan; Samaee, Milad; Santhanakrishnan, Arvind

2015-11-01

Roughly 30% of patients with systolic heart failure suffer from left ventricular dyssynchrony (LVD), in which mechanical discoordination of the ventricle walls leads to poor hemodynamics and suboptimal cardiac function. There is currently no clear mechanistic understanding of how abnormalities in septal-lateral (SL) wall motion affects left ventricle (LV) function, which is needed to improve the treatment of LVD using cardiac resynchronization therapy. We use an experimental flow phantom with an LV physical model to study mechanistic effects of SL wall motion delay on LV function. To simulate mechanical LVD, two rigid shafts were coupled to two segments (apical and mid sections) along the septal wall of the LV model. Flow through the LV model was driven using a piston pump, and stepper motors coupled to the above shafts were used to locally perturb the septal wall segments relative to the pump motion. 2D PIV was used to examine the intraventricular flow through the LV physical model. Alterations to SL delay results in a reduction in the kinetic energy (KE) of the flow field compared to synchronous SL motion. The effect of varying SL motion delay from 0% (synchronous) to 100% (out-of-phase) on KE and viscous dissipation will be presented. This research was supported by the Oklahoma Center for Advancement of Science and Technology (HR14-022).

Groupwise registration of cardiac perfusion MRI sequences using normalized mutual information in high dimension

NASA Astrophysics Data System (ADS)

Hamrouni, Sameh; Rougon, Nicolas; Pr"teux, Françoise

2011-03-01

In perfusion MRI (p-MRI) exams, short-axis (SA) image sequences are captured at multiple slice levels along the long-axis of the heart during the transit of a vascular contrast agent (Gd-DTPA) through the cardiac chambers and muscle. Compensating cardio-thoracic motions is a requirement for enabling computer-aided quantitative assessment of myocardial ischaemia from contrast-enhanced p-MRI sequences. The classical paradigm consists of registering each sequence frame on a reference image using some intensity-based matching criterion. In this paper, we introduce a novel unsupervised method for the spatio-temporal groupwise registration of cardiac p-MRI exams based on normalized mutual information (NMI) between high-dimensional feature distributions. Here, local contrast enhancement curves are used as a dense set of spatio-temporal features, and statistically matched through variational optimization to a target feature distribution derived from a registered reference template. The hard issue of probability density estimation in high-dimensional state spaces is bypassed by using consistent geometric entropy estimators, allowing NMI to be computed directly from feature samples. Specifically, a computationally efficient kth-nearest neighbor (kNN) estimation framework is retained, leading to closed-form expressions for the gradient flow of NMI over finite- and infinite-dimensional motion spaces. This approach is applied to the groupwise alignment of cardiac p-MRI exams using a free-form Deformation (FFD) model for cardio-thoracic motions. Experiments on simulated and natural datasets suggest its accuracy and robustness for registering p-MRI exams comprising more than 30 frames.

Meshless deformable models for 3D cardiac motion and strain analysis from tagged MRI.

PubMed

Wang, Xiaoxu; Chen, Ting; Zhang, Shaoting; Schaerer, Joël; Qian, Zhen; Huh, Suejung; Metaxas, Dimitris; Axel, Leon

2015-01-01

Tagged magnetic resonance imaging (TMRI) provides a direct and noninvasive way to visualize the in-wall deformation of the myocardium. Due to the through-plane motion, the tracking of 3D trajectories of the material points and the computation of 3D strain field call for the necessity of building 3D cardiac deformable models. The intersections of three stacks of orthogonal tagging planes are material points in the myocardium. With these intersections as control points, 3D motion can be reconstructed with a novel meshless deformable model (MDM). Volumetric MDMs describe an object as point cloud inside the object boundary and the coordinate of each point can be written in parametric functions. A generic heart mesh is registered on the TMRI with polar decomposition. A 3D MDM is generated and deformed with MR image tagging lines. Volumetric MDMs are deformed by calculating the dynamics function and minimizing the local Laplacian coordinates. The similarity transformation of each point is computed by assuming its neighboring points are making the same transformation. The deformation is computed iteratively until the control points match the target positions in the consecutive image frame. The 3D strain field is computed from the 3D displacement field with moving least squares. We demonstrate that MDMs outperformed the finite element method and the spline method with a numerical phantom. Meshless deformable models can track the trajectory of any material point in the myocardium and compute the 3D strain field of any particular area. The experimental results on in vivo healthy and patient heart MRI show that the MDM can fully recover the myocardium motion in three dimensions. Copyright © 2014. Published by Elsevier Inc.

Meshless deformable models for 3D cardiac motion and strain analysis from tagged MRI

PubMed Central

Wang, Xiaoxu; Chen, Ting; Zhang, Shaoting; Schaerer, Joël; Qian, Zhen; Huh, Suejung; Metaxas, Dimitris; Axel, Leon

2016-01-01

Tagged magnetic resonance imaging (TMRI) provides a direct and noninvasive way to visualize the in-wall deformation of the myocardium. Due to the through-plane motion, the tracking of 3D trajectories of the material points and the computation of 3D strain field call for the necessity of building 3D cardiac deformable models. The intersections of three stacks of orthogonal tagging planes are material points in the myocardium. With these intersections as control points, 3D motion can be reconstructed with a novel meshless deformable model (MDM). Volumetric MDMs describe an object as point cloud inside the object boundary and the coordinate of each point can be written in parametric functions. A generic heart mesh is registered on the TMRI with polar decomposition. A 3D MDM is generated and deformed with MR image tagging lines. Volumetric MDMs are deformed by calculating the dynamics function and minimizing the local Laplacian coordinates. The similarity transformation of each point is computed by assuming its neighboring points are making the same transformation. The deformation is computed iteratively until the control points match the target positions in the consecutive image frame. The 3D strain field is computed from the 3D displacement field with moving least squares. We demonstrate that MDMs outperformed the finite element method and the spline method with a numerical phantom. Meshless deformable models can track the trajectory of any material point in the myocardium and compute the 3D strain field of any particular area. The experimental results on in vivo healthy and patient heart MRI show that the MDM can fully recover the myocardium motion in three dimensions. PMID:25157446

A statistical model of catheter motion from interventional x-ray images: application to image-based gating

NASA Astrophysics Data System (ADS)

Panayiotou, M.; King, A. P.; Ma, Y.; Housden, R. J.; Rinaldi, C. A.; Gill, J.; Cooklin, M.; O'Neill, M.; Rhode, K. S.

2013-11-01

The motion and deformation of catheters that lie inside cardiac structures can provide valuable information about the motion of the heart. In this paper we describe the formation of a novel statistical model of the motion of a coronary sinus (CS) catheter based on principal component analysis of tracked electrode locations from standard mono-plane x-ray fluoroscopy images. We demonstrate the application of our model for the purposes of retrospective cardiac and respiratory gating of x-ray fluoroscopy images in normal dose x-ray fluoroscopy images, and demonstrate how a modification of the technique allows application to very low dose scenarios. We validated our method on ten mono-plane imaging sequences comprising a total of 610 frames from ten different patients undergoing radiofrequency ablation for the treatment of atrial fibrillation. For normal dose images we established systole, end-inspiration and end-expiration gating with success rates of 100%, 92.1% and 86.9%, respectively. For very low dose applications, the method was tested on the same ten mono-plane x-ray fluoroscopy sequences without noise and with added noise at signal to noise ratio (SNR) values of √50, √10, √8, √6, √5, √2 and √1 to simulate the image quality of increasingly lower dose x-ray images. The method was able to detect the CS catheter even in the lowest SNR images with median errors not exceeding 2.6 mm per electrode. Furthermore, gating success rates of 100%, 71.4% and 85.7% were achieved at the low SNR value of √2, representing a dose reduction of more than 25 times. Thus, the technique has the potential to extract useful information whilst substantially reducing the radiation exposure.

Segmentation of left ventricle myocardium in porcine cardiac cine MR images using a hybrid of fully convolutional neural networks and convolutional LSTM

NASA Astrophysics Data System (ADS)

Zhang, Dongqing; Icke, Ilknur; Dogdas, Belma; Parimal, Sarayu; Sampath, Smita; Forbes, Joseph; Bagchi, Ansuman; Chin, Chih-Liang; Chen, Antong

2018-03-01

In the development of treatments for cardiovascular diseases, short axis cardiac cine MRI is important for the assessment of various structural and functional properties of the heart. In short axis cardiac cine MRI, Cardiac properties including the ventricle dimensions, stroke volume, and ejection fraction can be extracted based on accurate segmentation of the left ventricle (LV) myocardium. One of the most advanced segmentation methods is based on fully convolutional neural networks (FCN) and can be successfully used to do segmentation in cardiac cine MRI slices. However, the temporal dependency between slices acquired at neighboring time points is not used. Here, based on our previously proposed FCN structure, we proposed a new algorithm to segment LV myocardium in porcine short axis cardiac cine MRI by incorporating convolutional long short-term memory (Conv-LSTM) to leverage the temporal dependency. In this approach, instead of processing each slice independently in a conventional CNN-based approach, the Conv-LSTM architecture captures the dynamics of cardiac motion over time. In a leave-one-out experiment on 8 porcine specimens (3,600 slices), the proposed approach was shown to be promising by achieving average mean Dice similarity coefficient (DSC) of 0.84, Hausdorff distance (HD) of 6.35 mm, and average perpendicular distance (APD) of 1.09 mm when compared with manual segmentations, which improved the performance of our previous FCN-based approach (average mean DSC=0.84, HD=6.78 mm, and APD=1.11 mm). Qualitatively, our model showed robustness against low image quality and complications in the surrounding anatomy due to its ability to capture the dynamics of cardiac motion.

Rigid-body transformation of list-mode projection data for respiratory motion correction in cardiac PET.

PubMed

Livieratos, L; Stegger, L; Bloomfield, P M; Schafers, K; Bailey, D L; Camici, P G

2005-07-21

High-resolution cardiac PET imaging with emphasis on quantification would benefit from eliminating the problem of respiratory movement during data acquisition. Respiratory gating on the basis of list-mode data has been employed previously as one approach to reduce motion effects. However, it results in poor count statistics with degradation of image quality. This work reports on the implementation of a technique to correct for respiratory motion in the area of the heart at no extra cost for count statistics and with the potential to maintain ECG gating, based on rigid-body transformations on list-mode data event-by-event. A motion-corrected data set is obtained by assigning, after pre-correction for detector efficiency and photon attenuation, individual lines-of-response to new detector pairs with consideration of respiratory motion. Parameters of respiratory motion are obtained from a series of gated image sets by means of image registration. Respiration is recorded simultaneously with the list-mode data using an inductive respiration monitor with an elasticized belt at chest level. The accuracy of the technique was assessed with point-source data showing a good correlation between measured and true transformations. The technique was applied on phantom data with simulated respiratory motion, showing successful recovery of tracer distribution and contrast on the motion-corrected images, and on patient data with C15O and 18FDG. Quantitative assessment of preliminary C15O patient data showed improvement in the recovery coefficient at the centre of the left ventricle.

Automatic intrinsic cardiac and respiratory gating from cone-beam CT scans of the thorax region

NASA Astrophysics Data System (ADS)

Hahn, Andreas; Sauppe, Sebastian; Lell, Michael; Kachelrieß, Marc

2016-03-01

We present a new algorithm that allows for raw data-based automated cardiac and respiratory intrinsic gating in cone-beam CT scans. It can be summarized in three steps: First, a median filter is applied to an initially reconstructed volume. The forward projection of this volume contains less motion information and is subtracted from the original projections. This results in new raw data that contain only moving and not static anatomy like bones, that would otherwise impede the cardiac or respiratory signal acquisition. All further steps are applied to these modified raw data. Second, the raw data are cropped to a region of interest (ROI). The ROI in the raw data is determined by the forward projection of a binary volume of interest (VOI) that includes the diaphragm for respiratory gating and most of the edge of the heart for cardiac gating. Third, the mean gray value in this ROI is calculated for every projection and the respiratory/cardiac signal is acquired using a bandpass filter. Steps two and three are carried out simultaneously for 64 or 1440 overlapping VOI inside the body for the respiratory or cardiac signal respectively. The signals acquired from each ROI are compared and the most consistent one is chosen as the desired cardiac or respiratory motion signal. Consistency is assessed by the standard deviation of the time between two maxima. The robustness and efficiency of the method is evaluated using simulated and measured patient data by computing the standard deviation of the mean signal difference between the ground truth and the intrinsic signal.

Detection and quantification of coronary calcium from dual energy chest x-rays: Phantom feasibility study.

PubMed

Zhou, Bo; Wen, Di; Nye, Katelyn; Gilkeson, Robert C; Eck, Brendan; Jordan, David; Wilson, David L

2017-10-01

We have demonstrated the ability to identify coronary calcium, a reliable biomarker of coronary artery disease, using nongated, 2-shot, dual energy (DE) chest x-ray imaging. Here we will use digital simulations, backed up by measurements, to characterize DE calcium signals and the role of potential confounds such as beam hardening, x-ray scatter, cardiac motion, and pulmonary artery pulsation. For the DE calcium signal, we will consider quantification, as compared to CT calcium score, and visualization. We created stylized and anatomical digital 3D phantoms including heart, lung, coronary calcium, spine, ribs, pulmonary artery, and adipose. We simulated high and low kVp x-ray acquisitions with x-ray spectra, energy dependent attenuation, scatter, ideal detector, and automatic exposure control (AEC). Phantoms allowed us to vary adipose thickness, cardiac motion, etc. We used specialized dual energy coronary calcium (DECC) processing that includes corrections for scatter and beam hardening. Beam hardening over a wide range of adipose thickness (0-30 cm) reduced the change in intensity of a coronary artery calcification (ΔI CAC ) by < 3% in DECC images. Scatter correction errors of ±50% affected the calcium signal (ΔI CAC ) in DECC images ±9%. If a simulated pulmonary artery fills with blood between exposures, it can give rise to a residual signal in DECC images, explaining pulmonary artery visibility in some clinical images. Residual misregistration can be mostly compensated by integrating signals in an enlarged region encompassing registration artifacts. DECC calcium score compared favorably to CT mass and volume scores over a number of phantom perturbations. Simulations indicate that proper DECC processing can faithfully recover coronary calcium signals. Beam hardening, errors in scatter estimation, cardiac motion, calcium residual misregistration etc., are all manageable. Simulations are valuable as we continue to optimize DE coronary calcium image processing and quantitative analysis. © 2017 American Association of Physicists in Medicine.

Outcome by Exercise Echocardiography in Patients with Low Pretest Probability of Coronary Artery Disease.

PubMed

Peteiro, Jesus; Bouzas-Mosquera, Alberto; Broullon, Javier; Sanchez-Fernandez, Gabriel; Perez-Cebey, Lucia; Yañez, Juan; Martinez, Dolores; Vazquez-Rodriguez, Jose M

2016-08-01

Recommendations for testing in patients with low pretest probability of coronary artery disease differ in guidelines from no testing at all to different tests. The aim of this study was to assess the value of exercise echocardiography (ExE) to define outcome in this population. A retrospective analysis was conducted of 1,436 patients with low pretest probability of coronary artery disease (<15%) who underwent initial ExE. Overall mortality, major adverse cardiac events (MACEs), defined as cardiac death or nonfatal myocardial infarction, and revascularization during follow-up, were assessed. Ischemia (development of new wall motion abnormalities with exercise) and fixed wall motion abnormalities were measured. The mean age was 50 ± 12 years. Resting wall motion abnormalities were seen in 13 patients (0.9%) and ischemia in 108 (7.5%). During follow-up, 38 patients died, 10 of cardiac death (annualized death rate, 0.39%); 20 patients had MACEs (annualized MACE rate, 0.21%); and 48 patients (29 with ischemia) underwent revascularization (annualized revascularization rate, 0.51%). The number and percentage of MACEs in the abnormal and normal ExE groups were similar (two [1.7%] vs 18 [1.4%], P = .70), as was the annualized MACE rate (0.31% vs 0.21%, P = .50). Peak left ventricular ejection fraction exhibited a nonsignificant trend for predicting MACEs (P = .11). The number of studies needed to detect an abnormal finding was 12.6 and to detect a patient with extensive ischemia was 26.1. ExE offers limited prognostic information in patients with low pretest probability of coronary artery disease. The small number of abnormal findings on ExE and low event rates and the large number of studies needed to detect an abnormal finding limit further the value of imaging in this population. Copyright © 2016 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.

Motion correction options in PET/MRI.

PubMed

Catana, Ciprian

2015-05-01

Subject motion is unavoidable in clinical and research imaging studies. Breathing is the most important source of motion in whole-body PET and MRI studies, affecting not only thoracic organs but also those in the upper and even lower abdomen. The motion related to the pumping action of the heart is obviously relevant in high-resolution cardiac studies. These two sources of motion are periodic and predictable, at least to a first approximation, which means certain techniques can be used to control the motion (eg, by acquiring the data when the organ of interest is relatively at rest). Additionally, nonperiodic and unpredictable motion can also occur during the scan. One obvious limitation of methods relying on external devices (eg, respiratory bellows or the electrocardiogram signal to monitor the respiratory or cardiac cycle, respectively) to trigger or gate the data acquisition is that the complex motion of internal organs cannot be fully characterized. However, detailed information can be obtained using either the PET or MRI data (or both) allowing the more complete characterization of the motion field so that a motion model can be built. Such a model and the information derived from simple external devices can be used to minimize the effects of motion on the collected data. In the ideal case, all the events recorded during the PET scan would be used to generate a motion-free or corrected PET image. The detailed motion field can be used for this purpose by applying it to the PET data before, during, or after the image reconstruction. Integrating all these methods for motion control, characterization, and correction into a workflow that can be used for routine clinical studies is challenging but could potentially be extremely valuable given the improvement in image quality and reduction of motion-related image artifacts. Copyright © 2015 Elsevier Inc. All rights reserved.

Heart deformation analysis for automated quantification of cardiac function and regional myocardial motion patterns: A proof of concept study in patients with cardiomyopathy and healthy subjects.

PubMed

Lin, Kai; Collins, Jeremy D; Chowdhary, Varun; Markl, Michael; Carr, James C

2016-10-01

To test the performance of HDA in characterizing left ventricular (LV) function and regional myocardial motion patterns in the context of cardiomyopathy based on cine cardiovascular magnetic resonance (CMR). Following the approval of the institutional review board (IRB), standard cine images of 45 subjects, including 15 healthy volunteers, 15 patients with hypertrophic cardiomyopathy (HCM) and 15 patients with dilated cardiomyopathy (DCM) were retrospectively analyzed using HDA. The variations of LV ejection fraction (LVEF), LV mass (LVM), and regional myocardial motion indices, including radial (Drr), circumferential (Dcc) displacement, radial (Vrr) and circumferential (Vcc) velocity, radial (Err), circumferential (Ecc) and shear (Ess) strain and radial (SRr) and circumferential (SRc) strain rate, were calculated and compared among subject groups. Inter-study reproducibility of HDA-derived myocardial motion indices were tested on 15 volunteers by using intra-class correlation coefficient (ICC) and coefficient of variation (CoV). HDA identified significant differences in cardiac function and motion indices between subject groups. DCM patients had significantly lower LVEF (33.5±9.65%), LVM (105.88±21.93g), peak Drr (0.29±0.11cm), Vrr-sys (2.14±0.72cm/s), Err (0.17±0.08), Ecc (-0.08±0.03), SRr-sys (0.91±0.44s(-1)) and SRc-sys (-0.64±0.27s(-1)) compared to the other two groups. HCM patients demonstrated increased LVM (171.69±34.19) and lower peak Vcc-dia (0.78±0.30cm/s) than other subjects. Good inter-study reproducibility was found for all HDA-derived myocardial indices in healthy volunteers (ICC=0.664-0.942, CoV=15.1%-37.1%). Without the need for operator interaction, HDA is a reproducible method for the automated characterization of global and regional LV function in the context of cardiomyopathy. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Live dynamic OCT imaging of cardiac structure and function in mouse embryos with 43 Hz direct volumetric data acquisition

NASA Astrophysics Data System (ADS)

Wang, Shang; Singh, Manmohan; Lopez, Andrew L.; Wu, Chen; Raghunathan, Raksha; Schill, Alexander; Li, Jiasong; Larin, Kirill V.; Larina, Irina V.

2016-03-01

Efficient phenotyping of cardiac dynamics in live mouse embryos has significant implications on understanding of early mammalian heart development and congenital cardiac defects. Recent studies established optical coherence tomography (OCT) as a powerful tool for live embryonic heart imaging in various animal models. However, current four-dimensional (4D) OCT imaging of the beating embryonic heart largely relies on gated data acquisition or postacquisition synchronization, which brings errors when cardiac cycles lack perfect periodicity and is time consuming and computationally expensive. Here, we report direct 4D OCT imaging of the structure and function of cardiac dynamics in live mouse embryos achieved by employing a Fourier domain mode-locking swept laser source that enables ~1.5 MHz A-line rate. Through utilizing both forward and backward scans of a resonant mirror, we obtained a ~6.4 kHz frame rate, which allows for a direct volumetric data acquisition speed of ~43 Hz, around 20 times of the early-stage mouse embryonic heart rate. Our experiments were performed on mouse embryos at embryonic day 9.5. Time-resolved 3D cardiodynamics clearly shows the heart structure in motion. We present analysis of cardiac wall movement and its velocity from the primitive atrium and ventricle. Our results suggest that the combination of ultrahigh-speed OCT imaging with live embryo culture could be a useful embryonic heart phenotyping approach for mouse mutants modeling human congenital heart diseases.

Long-term prognostic value of a comprehensive assessment of cardiac magnetic resonance indexes after an ST-segment elevation myocardial infarction.

PubMed

Merlos, Pilar; López-Lereu, Maria P; Monmeneu, Jose V; Sanchis, Juan; Núñez, Julio; Bonanad, Clara; Valero, Ernesto; Miñana, Gema; Chaustre, Fabián; Gómez, Cristina; Oltra, Ricardo; Palacios, Lorena; Bosch, Maria J; Navarro, Vicente; Llácer, Angel; Chorro, Francisco J; Bodí, Vicente

2013-08-01

A variety of cardiac magnetic resonance indexes predict mid-term prognosis in ST-segment elevation myocardial infarction patients. The extent of transmural necrosis permits simple and accurate prediction of systolic recovery. However, its long-term prognostic value beyond a comprehensive clinical and cardiac magnetic resonance evaluation is unknown. We hypothesized that a simple semiquantitative assessment of the extent of transmural necrosis is the best resonance index to predict long-term outcome soon after a first ST-segment elevation myocardial infarction. One week after a first ST-segment elevation myocardial infarction we carried out a comprehensive quantification of several resonance parameters in 206 consecutive patients. A semiquantitative assessment (altered number of segments in the 17-segment model) of edema, baseline and post-dobutamine wall motion abnormalities, first pass perfusion, microvascular obstruction, and the extent of transmural necrosis was also performed. During follow-up (median 51 months), 29 patients suffered a major adverse cardiac event (8 cardiac deaths, 11 nonfatal myocardial infarctions, and 10 readmissions for heart failure). Major cardiac events were associated with more severely altered quantitative and semiquantitative resonance indexes. After a comprehensive multivariate adjustment, the extent of transmural necrosis was the only resonance index independently related to the major cardiac event rate (hazard ratio=1.34 [1.19-1.51] per each additional segment displaying>50% transmural necrosis, P<.001). A simple and non-time consuming semiquantitative analysis of the extent of transmural necrosis is the most powerful cardiac magnetic resonance index to predict long-term outcome soon after a first ST-segment elevation myocardial infarction. Copyright © 2013 Sociedad Española de Cardiología. Published by Elsevier Espana. All rights reserved.

Respiratory motion compensated overlay of surface models from cardiac MR on interventional x-ray fluoroscopy for guidance of cardiac resynchronization therapy procedures

NASA Astrophysics Data System (ADS)

Manzke, R.; Bornstedt, A.; Lutz, A.; Schenderlein, M.; Hombach, V.; Binner, L.; Rasche, V.

2010-02-01

Various multi-center trials have shown that cardiac resynchronization therapy (CRT) is an effective procedure for patients with end-stage drug invariable heart failure (HF). Despite the encouraging results of CRT, at least 30% of patients do not respond to the treatment. Detailed knowledge of the cardiac anatomy (coronary venous tree, left ventricle), functional parameters (i.e. ventricular synchronicity) is supposed to improve CRT patient selection and interventional lead placement for reduction of the number of non-responders. As a pre-interventional imaging modality, cardiac magnetic resonance (CMR) imaging has the potential to provide all relevant information. With functional information from CMR optimal implantation target sites may be better identified. Pre-operative CMR could also help to determine whether useful vein target segments are available for lead placement. Fused with X-ray, the mainstay interventional modality, improved interventional guidance for lead-placement could further help to increase procedure outcome. In this contribution, we present novel and practicable methods for a) pre-operative functional and anatomical imaging of relevant cardiac structures to CRT using CMR, b) 2D-3D registration of CMR anatomy and functional meshes with X-ray vein angiograms and c) real-time capable breathing motion compensation for improved fluoroscopy mesh overlay during the intervention based on right ventricular pacer lead tracking. With these methods, enhanced interventional guidance for left ventricular lead placement is provided.

Current Status of 3-Dimensional Speckle Tracking Echocardiography: A Review from Our Experiences

PubMed Central

Ishizu, Tomko; Aonuma, Kazutaka

2014-01-01

Cardiac function analysis is the main focus of echocardiography. Left ventricular ejection fraction (LVEF) has been the clinical standard, however, LVEF is not enough to investigate myocardial function. For the last decade, speckle tracking echocardiography (STE) has been the novel clinical tool for regional and global myocardial function analysis. However, 2-dimensional imaging methods have limitations in assessing 3-dimensional (3D) cardiac motion. In contrast, 3D echocardiography also has been widely used, in particular, to measure LV volume measurements and assess valvular diseases. Joining the technology bandwagon, 3D-STE was introduced in 2008. Experimental studies and clinical investigations revealed the reliability and feasibility of 3D-STE-derived data. In addition, 3D-STE provides a novel deformation parameter, area change ratio, which have the potential for more accurate assessment of overall and regional myocardial function. In this review, we introduced the features of the methodology, validation, and clinical application of 3D-STE based on our experiences for 7 years. PMID:25031794

Three-dimensional quantification of cardiac surface motion: a newly developed three-dimensional digital motion-capture and reconstruction system for beating heart surgery.

PubMed

Watanabe, Toshiki; Omata, Sadao; Odamura, Motoki; Okada, Masahumi; Nakamura, Yoshihiko; Yokoyama, Hitoshi

2006-11-01

This study aimed to evaluate our newly developed 3-dimensional digital motion-capture and reconstruction system in an animal experiment setting and to characterize quantitatively the three regional cardiac surface motions, in the left anterior descending artery, right coronary artery, and left circumflex artery, before and after stabilization using a stabilizer. Six pigs underwent a full sternotomy. Three tiny metallic markers (diameter 2 mm) coated with a reflective material were attached on three regional cardiac surfaces (left anterior descending, right coronary, and left circumflex coronary artery regions). These markers were captured by two high-speed digital video cameras (955 frames per second) as 2-dimensional coordinates and reconstructed to 3-dimensional data points (about 480 xyz-position data per second) by a newly developed computer program. The remaining motion after stabilization ranged from 0.4 to 1.01 mm at the left anterior descending, 0.91 to 1.52 mm at the right coronary artery, and 0.53 to 1.14 mm at the left circumflex regions. Significant differences before and after stabilization were evaluated in maximum moving velocity (left anterior descending 456.7 +/- 178.7 vs 306.5 +/- 207.4 mm/s; right coronary artery 574.9 +/- 161.7 vs 446.9 +/- 170.7 mm/s; left circumflex 578.7 +/- 226.7 vs 398.9 +/- 192.6 mm/s; P < .0001) and maximum acceleration (left anterior descending 238.8 +/- 137.4 vs 169.4 +/- 132.7 m/s2; right coronary artery 315.0 +/- 123.9 vs 242.9 +/- 120.6 m/s2; left circumflex 307.9 +/- 151.0 vs 217.2 +/- 132.3 m/s2; P < .0001). This system is useful for a precise quantification of the heart surface movement. This helps us better understand the complexity of the heart, its motion, and the need for developing a better stabilizer for beating heart surgery.

Hereditary Lysozyme Amyloidosis Variant p.Leu102Ser Associates with Unique Phenotype

PubMed Central

Nasr, Samih H.; Dasari, Surendra; Mills, John R.; Theis, Jason D.; Zimmermann, Michael T.; Fonseca, Rafael; Vrana, Julie A.; Lester, Steven J.; McLaughlin, Brooke M.; Gillespie, Robert; Highsmith, W. Edward; Lee, John J.; Dispenzieri, Angela

2017-01-01

Lysozyme amyloidosis (ALys) is a rare form of hereditary amyloidosis that typically manifests with renal impairment, gastrointestinal (GI) symptoms, and sicca syndrome, whereas cardiac involvement is exceedingly rare and neuropathy has not been reported. Here, we describe a 40-year-old man with renal impairment, cardiac and GI symptoms, and peripheral neuropathy. Renal biopsy specimen analysis revealed amyloidosis with extensive involvement of glomeruli, vessels, and medulla. Amyloid was also detected in the GI tract. Echocardiographic and electrocardiographic findings were consistent with cardiac involvement. Proteomic analysis of Congo red–positive renal and GI amyloid deposits detected abundant lysozyme C protein. DNA sequencing of the lysozyme gene in the patient and his mother detected a heterozygous c.305T>C alteration in exon 3, which causes a leucine to serine substitution at codon 102 (Human Genome Variation Society nomenclature: p.Leu102Ser; legacy designation: L84S). We also detected the mutant peptide in the proband’s renal and GI amyloid deposits. PolyPhen analysis predicted that the mutation damages the encoded protein. Molecular dynamics simulations suggested that the pathogenesis of ALys p.Leu102Ser is mediated by shifting the position of the central β-hairpin coordinated with an antiparallel motion of the C-terminal helix, which may alter the native-state structural ensemble of the molecule, leading to aggregation-prone intermediates. PMID:28049649

Cardiac image modelling: Breadth and depth in heart disease.

PubMed

Suinesiaputra, Avan; McCulloch, Andrew D; Nash, Martyn P; Pontre, Beau; Young, Alistair A

2016-10-01

With the advent of large-scale imaging studies and big health data, and the corresponding growth in analytics, machine learning and computational image analysis methods, there are now exciting opportunities for deepening our understanding of the mechanisms and characteristics of heart disease. Two emerging fields are computational analysis of cardiac remodelling (shape and motion changes due to disease) and computational analysis of physiology and mechanics to estimate biophysical properties from non-invasive imaging. Many large cohort studies now underway around the world have been specifically designed based on non-invasive imaging technologies in order to gain new information about the development of heart disease from asymptomatic to clinical manifestations. These give an unprecedented breadth to the quantification of population variation and disease development. Also, for the individual patient, it is now possible to determine biophysical properties of myocardial tissue in health and disease by interpreting detailed imaging data using computational modelling. For these population and patient-specific computational modelling methods to develop further, we need open benchmarks for algorithm comparison and validation, open sharing of data and algorithms, and demonstration of clinical efficacy in patient management and care. The combination of population and patient-specific modelling will give new insights into the mechanisms of cardiac disease, in particular the development of heart failure, congenital heart disease, myocardial infarction, contractile dysfunction and diastolic dysfunction. Copyright © 2016. Published by Elsevier B.V.

In vivo high-resolution structural imaging of large arteries in small rodents using two-photon laser scanning microscopy

NASA Astrophysics Data System (ADS)

Megens, Remco T. A.; Reitsma, Sietze; Prinzen, Lenneke; Oude Egbrink, Mirjam G. A.; Engels, Wim; Leenders, Peter J. A.; Brunenberg, Ellen J. L.; Reesink, Koen D.; Janssen, Ben J. A.; Ter Haar Romeny, Bart M.; Slaaf, Dick W.; van Zandvoort, Marc A. M. J.

2010-01-01

In vivo (molecular) imaging of the vessel wall of large arteries at subcellular resolution is crucial for unraveling vascular pathophysiology. We previously showed the applicability of two-photon laser scanning microscopy (TPLSM) in mounted arteries ex vivo. However, in vivo TPLSM has thus far suffered from in-frame and between-frame motion artifacts due to arterial movement with cardiac and respiratory activity. Now, motion artifacts are suppressed by accelerated image acquisition triggered on cardiac and respiratory activity. In vivo TPLSM is performed on rat renal and mouse carotid arteries, both surgically exposed and labeled fluorescently (cell nuclei, elastin, and collagen). The use of short acquisition times consistently limit in-frame motion artifacts. Additionally, triggered imaging reduces between-frame artifacts. Indeed, structures in the vessel wall (cell nuclei, elastic laminae) can be imaged at subcellular resolution. In mechanically damaged carotid arteries, even the subendothelial collagen sheet (~1 μm) is visualized using collagen-targeted quantum dots. We demonstrate stable in vivo imaging of large arteries at subcellular resolution using TPLSM triggered on cardiac and respiratory cycles. This creates great opportunities for studying (diseased) arteries in vivo or immediate validation of in vivo molecular imaging techniques such as magnetic resonance imaging (MRI), ultrasound, and positron emission tomography (PET).

The safety and clinical usefulness of dobutamine stress echocardiography among octogenarians.

PubMed

O'Driscoll, Jamie M; Marciniak, Anna; Ray, Kausik K; Schmid, Katharina; Smith, Robert; Sharma, Rajan

2014-07-01

Increasing numbers of octogenarians are being referred for investigation of chest pain. While dobutamine stress echocardiography (DSE) has been shown to be useful in younger patients, its role among octogenarians remains unclear. This investigation aimed to investigate the safety and prognostic benefits of DSE on cardiac events and total mortality in octogenarians. 550 consecutive patients aged ≥80 years underwent DSE for suspected cardiac chest pain. All subjects were followed-up prospectively until March 2011, and the study end-points were a major cardiac event and total mortality. One hundred and eighty-three (33%) patients had a positive DSE result, 271 (49%) had a normal study, and 164 (30%) had fixed-wall motion abnormalities. During a mean follow-up of 2.14±1.13 years, there were 217 (39%) cardiac events and 63 (11%) deaths, of which 46 (73%) were cardiac. The absolute risk of cardiac events increased with burden of ischaemia on DSE, from 13%/year (none), to 26%/year (1-3 ischaemic (LV) segments), and 38%/year (>3 ischaemic LV segments), p<0.001. Any ischaemia was associated with an additional 13 cardiac events per 100 person-years. In multivariate analysis, compared with non-ischaemic patients, the relative hazard of cardiac events for 1-3 and >3 ischaemic LV segments were 1.34 (95% CI 1.13 to 1.29) and 1.86 (95% CI 1.16 to 2.98), respectively. Addition of echocardiographic parameters to basic models improved the C statistic from 0.77 to 0.89 (p<0.001). Among octogenarians referred with suspected cardiac chest pain, DSE is safe and, importantly, identifies a subset at high risk of cardiac events. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Evaluation of Rigid-Body Motion Compensation in Cardiac Perfusion SPECT Employing Polar-Map Quantification

PubMed Central

Pretorius, P. Hendrik; Johnson, Karen L.; King, Michael A.

2016-01-01

We have recently been successful in the development and testing of rigid-body motion tracking, estimation and compensation for cardiac perfusion SPECT based on a visual tracking system (VTS). The goal of this study was to evaluate in patients the effectiveness of our rigid-body motion compensation strategy. Sixty-four patient volunteers were asked to remain motionless or execute some predefined body motion during an additional second stress perfusion acquisition. Acquisitions were performed using the standard clinical protocol with 64 projections acquired through 180 degrees. All data were reconstructed with an ordered-subsets expectation-maximization (OSEM) algorithm using 4 projections per subset and 5 iterations. All physical degradation factors were addressed (attenuation, scatter, and distance dependent resolution), while a 3-dimensional Gaussian rotator was used during reconstruction to correct for six-degree-of-freedom (6-DOF) rigid-body motion estimated by the VTS. Polar map quantification was employed to evaluate compensation techniques. In 54.7% of the uncorrected second stress studies there was a statistically significant difference in the polar maps, and in 45.3% this made a difference in the interpretation of segmental perfusion. Motion correction reduced the impact of motion such that with it 32.8 % of the polar maps were statistically significantly different, and in 14.1% this difference changed the interpretation of segmental perfusion. The improvement shown in polar map quantitation translated to visually improved uniformity of the SPECT slices. PMID:28042170

Phase analysis in the Wolff-Parkinson-White syndrome with surgically proven accessory conduction pathways: concise communication

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakajima, K.; Bunko, H.; Tada, A.

1984-01-01

Twenty-one patients with the Wolff-Parkinson-White (WPW) syndrome who underwent surgical division of the accessory conduction pathway (ACP) were studied by gated blood-pool scintigraphy. In each case, a functional image of the phase was generated, based on the fundamental frequency of the Fourier transform. The location of the ACP was confirmed by electrophysiologic study, epicardial mapping, and surgery. Phase analysis identified the side of preexcitation correctly in 16 out of 20 patients with WPW syndrome with a delta wave. All patients with right-cardiac type (N=9) had initial contraction in the right ventricle (RV). In patients with left-cardiac type (N=10), six hadmore » initial movement in the left ventricle (LV); but in the other four the ACPs in the anterior or lateral wall of the left ventricle (LV) could not be detected. In patients with multiple ACPs (N=2), one right-cardiac type had initial contraction in the RV, while in the other (with an intermittent WPW syndrome) the ACP was not detected. These observations indicate that abnormal wall motion is associated with the conduction anomalies of the WPW syndrome. We conclude that phase analysis can correctly identify the side of initial contraction in the WPW syndrome before and after surgery. However, as a method of preoperative study, it seems difficult to determine the precise site of the ACP by phase analysis alone.« less

SU-C-303-06: Treatment Planning Study for Non-Invasive Cardiac Arrhythmia Ablation with Scanned Carbon Ions in An Animal Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eichhorn, A; Constantinescu, A; Prall, M

Purpose: Scanned carbon ion beams might offer a non-invasive alternative treatment for cardiac arrhythmia, which are a major health-burden. We studied the feasibility of this procedure in an animal model. The underlying treatment planning and motion mitigation strategies will be presented. Methods: The study was carried out in 15 pigs, randomly distributed to 3 target groups: atrioventricular node (AVN, 8 animals with 25, 40, and 55 Gy target dose), left ventricular free-wall (LV, 4 animals with 40 Gy) and superior pulmonary vein (SPV, 3 animals with 40 Gy). Breathing motion was suppressed by repeated enforced breathholds at end exhale. Cardiacmore » motion was mitigated by an inhomogeneous rescanning scheme with up to 15 rescans. The treatment planning was performed using the GSI in-house software TRiP4D on cardiac-gated 4DCTs, applying a range-considering ITV based on an extended CTV. For AVN and SPV isotropic 5 mm margins were applied to the CTV, while for the LV 2mm+2% range margins were used. The opposing fields for AVN and LV targets were optimized independently (SFUD), while SPV treatments were optimized as IMPT deliveries, including dose restrictions to the radiosensitive AVN. Results: Median value of D{sub 95} over all rescanning simulations was 99.1% (AVN), 98.0% (SPV) and 98.3% (LV) for the CTV and 94.7% (AVN) and 92.7% (SPV) for the PTV, respectively. The median D{sub 5}-D{sub 95} was improved with rescanning compared to unmitigated delivery from 13.3 to 6.5% (CTV) and from 23.4 to 11.6% (PTV). ICRP dose limits for aorta, trachea, esophagus and skin were respected. The maximal dose in the coronary arteries was limited to 30 Gy. Conclusion: We demonstrated the feasibility of a homogeneous dose delivery to different cardiac structures in a porcine model using a time-optimized inhomogeneous rescanning scheme. The presented treatment planning strategies were applied in a pig study with the analysis ongoing. Funding: This work was supported in part by the Helmholtz Association, the American Heart Association Midwest Affiliate Postdoctoral Fellowship Grant, the Mayo Clinic Foundation, and the Goldsmith Foundation.« less

A New Parameter for Cardiac Efficiency Analysis

NASA Astrophysics Data System (ADS)

Borazjani, Iman; Rajan, Navaneetha Krishnan; Song, Zeying; Hoffmann, Kenneth; MacMahon, Eileen; Belohlavek, Marek

2014-11-01

Detecting and evaluating a heart with suboptimal pumping efficiency is a significant clinical goal. However, the routine parameters such as ejection fraction, quantified with current non-invasive techniques are not predictive of heart disease prognosis. Furthermore, they only represent left-ventricular (LV) ejection function and not the efficiency, which might be affected before apparent changes in the function. We propose a new parameter, called the hemodynamic efficiency (H-efficiency) and defined as the ratio of the useful to total power, for cardiac efficiency analysis. Our results indicate that the change in the shape/motion of the LV will change the pumping efficiency of the LV even if the ejection fraction is kept constant at 55% (normal value), i.e., H-efficiency can be used for suboptimal cardiac performance diagnosis. To apply H-efficiency on a patient-specific basis, we are developing a system that combines echocardiography (echo) and computational fluid dynamics (CFD) to provide the 3D pressure and velocity field to directly calculate the H-efficiency parameter. Because the method is based on clinically used 2D echo, which has faster acquisition time and lower cost relative to other imaging techniques, it can have a significant impact on a large number of patients. This work is partly supported by the American Heart Association.

Determination of Three-Dimensional Left Ventricle Motion to Analyze Ventricular Dyssyncrony in SPECT Images

NASA Astrophysics Data System (ADS)

Rebelo, Marina de Sá; Aarre, Ann Kirstine Hummelgaard; Clemmesen, Karen-Louise; Brandão, Simone Cristina Soares; Giorgi, Maria Clementina; Meneghetti, José Cláudio; Gutierrez, Marco Antonio

2009-12-01

A method to compute three-dimension (3D) left ventricle (LV) motion and its color coded visualization scheme for the qualitative analysis in SPECT images is proposed. It is used to investigate some aspects of Cardiac Resynchronization Therapy (CRT). The method was applied to 3D gated-SPECT images sets from normal subjects and patients with severe Idiopathic Heart Failure, before and after CRT. Color coded visualization maps representing the LV regional motion showed significant difference between patients and normal subjects. Moreover, they indicated a difference between the two groups. Numerical results of regional mean values representing the intensity and direction of movement in radial direction are presented. A difference of one order of magnitude in the intensity of the movement on patients in relation to the normal subjects was observed. Quantitative and qualitative parameters gave good indications of potential application of the technique to diagnosis and follow up of patients submitted to CRT.

[Development of an automated processing method to detect coronary motion for coronary magnetic resonance angiography].

PubMed

Asou, Hiroya; Imada, N; Sato, T

2010-06-20

On coronary MR angiography (CMRA), cardiac motions worsen the image quality. To improve the image quality, detection of cardiac especially for individual coronary motion is very important. Usually, scan delay and duration were determined manually by the operator. We developed a new evaluation method to calculate static time of individual coronary artery. At first, coronary cine MRI was taken at the level of about 3 cm below the aortic valve (80 images/R-R). Chronological change of the signals were evaluated with Fourier transformation of each pixel of the images were done. Noise reduction with subtraction process and extraction process were done. To extract higher motion such as coronary arteries, morphological filter process and labeling process were added. Using these imaging processes, individual coronary motion was extracted and individual coronary static time was calculated automatically. We compared the images with ordinary manual method and new automated method in 10 healthy volunteers. Coronary static times were calculated with our method. Calculated coronary static time was shorter than that of ordinary manual method. And scan time became about 10% longer than that of ordinary method. Image qualities were improved in our method. Our automated detection method for coronary static time with chronological Fourier transformation has a potential to improve the image quality of CMRA and easy processing.

Statistical Analysis of speckle noise reduction techniques for echocardiographic Images

NASA Astrophysics Data System (ADS)

Saini, Kalpana; Dewal, M. L.; Rohit, Manojkumar

2011-12-01

Echocardiography is the safe, easy and fast technology for diagnosing the cardiac diseases. As in other ultrasound images these images also contain speckle noise. In some cases this speckle noise is useful such as in motion detection. But in general noise removal is required for better analysis of the image and proper diagnosis. Different Adaptive and anisotropic filters are included for statistical analysis. Statistical parameters such as Signal-to-Noise Ratio (SNR), Peak Signal-to-Noise Ratio (PSNR), and Root Mean Square Error (RMSE) calculated for performance measurement. One more important aspect that there may be blurring during speckle noise removal. So it is prefered that filter should be able to enhance edges during noise removal.

2D XD-GRASP provides better image quality than conventional 2D cardiac cine MRI for patients who cannot suspend respiration

PubMed Central

Piekarski, Eve; Chitiboi, Teodora; Ramb, Rebecca; Latson, Larry A; Bhatla, Puneet; Feng, Li; Axel, Leon

2017-01-01

Object Residual respiratory motion degrades image quality in conventional cardiac cine MRI (CCMR). We evaluated whether a free-breathing (FB) radial imaging CCMR sequence with compressed sensing reconstruction (eXtra-Dimension (e.g. cardiac and respiratory phases) Golden-angle RAdial Sparse Parallel, or XD-GRASP) could provide better image quality than a conventional Cartesian breath-held (BH) sequence, in an unselected population of patients undergoing clinical CCMR. Material and Methods 101 patients who underwent BH and FB imaging in a mid-ventricular short-axis plane at a matching location were included. Visual and quantitative image analysis was performed by two blinded experienced readers, using a 5-point qualitative scale to score overall image quality and visual signal-to-noise ratio (SNR) grade, with measures of noise and sharpness. End-diastole (ED) and end-systole (ES) left-ventricular areas were also measured and compared for both BH and FB images. Results Image quality was generally better with the BH cines (overall quality grade BH vs FB: 4 vs 2.9, p<0.001; noise 0.06 vs 0.08 p< 0.001; SNR grade: 4.1 vs 3, p<0.001), except for sharpness (p=0.48). There were no significant differences between BH and FB images regarding ED or ES areas (p=0.35 and 0.12). 18 of the 101 patients had impaired BH image quality (grades 1 or 2). In this subgroup, image quality of the FB images was better (p=0.0032), as was the SNR grade (p=0.003), but there were no significant differences regarding noise and sharpness (p=0.45, p=0.47). Conclusion Although FB XD-GRASP CCMR was visually inferior to conventional BH cardiac cine in general, it provided improved image quality in the subgroup of patients presenting respiratory motion-induced artifacts on breath-held images. PMID:29067539

Cardiac gating with a pulse oximeter for dual-energy imaging.

PubMed

Shkumat, N A; Siewerdsen, J H; Dhanantwari, A C; Williams, D B; Paul, N S; Yorkston, J; Van Metter, R

2008-11-07

The development and evaluation of a prototype cardiac gating system for double-shot dual-energy (DE) imaging is described. By acquiring both low- and high-kVp images during the resting phase of the cardiac cycle (diastole), heart misalignment between images can be reduced, thereby decreasing the magnitude of cardiac motion artifacts. For this initial implementation, a fingertip pulse oximeter was employed to measure the peripheral pulse waveform ('plethysmogram'), offering potential logistic, cost and workflow advantages compared to an electrocardiogram. A gating method was developed that accommodates temporal delays due to physiological pulse propagation, oximeter waveform processing and the imaging system (software, filter-wheel, anti-scatter Bucky-grid and flat-panel detector). Modeling the diastolic period allowed the calculation of an implemented delay, t(imp), required to trigger correctly during diastole at any patient heart rate (HR). The model suggests a triggering scheme characterized by two HR regimes, separated by a threshold, HR(thresh). For rates at or below HR(thresh), sufficient time exists to expose on the same heartbeat as the plethysmogram pulse [t(imp)(HR) = 0]. Above HR(thresh), a characteristic t(imp)(HR) delays exposure to the subsequent heartbeat, accounting for all fixed and variable system delays. Performance was evaluated in terms of accuracy and precision of diastole-trigger coincidence and quantitative evaluation of artifact severity in gated and ungated DE images. Initial implementation indicated 85% accuracy in diastole-trigger coincidence. Through the identification of an improved HR estimation method (modified temporal smoothing of the oximeter waveform), trigger accuracy of 100% could be achieved with improved precision. To quantify the effect of the gating system on DE image quality, human observer tests were conducted to measure the magnitude of cardiac artifact under conditions of successful and unsuccessful diastolic gating. Six observers independently measured the artifact in 111 patient DE images. The data indicate that successful diastolic gating results in a statistically significant reduction (p < 0.001) in the magnitude of cardiac motion artifact, with residual artifact attributed primarily to gross patient motion.

A System for Seismocardiography-Based Identification of Quiescent Heart Phases: Implications for Cardiac Imaging

PubMed Central

Wick, Carson A.; Su, Jin-Jyh; McClellan, James H.; Brand, Oliver; Bhatti, Pamela T.; Buice, Ashley L.; Stillman, Arthur E.; Tang, Xiangyang; Tridandapani, Srini

2013-01-01

Seismocardiography (SCG), a representation of mechanical heart motion, may more accurately determine periods of cardiac quiescence within a cardiac cycle than the electrically derived electrocardiogram (EKG) and, thus, may have implications for gating in cardiac computed tomography. We designed and implemented a system to synchronously acquire echocardiography, EKG, and SCG data. The device was used to study the variability between EKG and SCG and characterize the relationship between the mechanical and electrical activity of the heart. For each cardiac cycle, the feature of the SCG indicating Aortic Valve Closure was identified and its time position with respect to the EKG was observed. This position was found to vary for different heart rates and between two human subjects. A color map showing the magnitude of the SCG acceleration and computed velocity was derived, allowing for direct visualization of quiescent phases of the cardiac cycle with respect to heart rate. PMID:22581141

Congenital Complete Absence of Pericardium Masquerading as Pulmonary Embolism

PubMed Central

Tariq, Saad; Mahmood, Sultan; Madeira, Samuel; Tarasov, Ethan

2013-01-01

Congenital absence of the pericardium is a rare cardiac condition, which can be either isolated or associated with other cardiac and extracardiac anomalies. There are six different types, depending on the severity of the involvement. Most of the patients with this defect are asymptomatic, especially the ones with complete absence of the pericardium. However, some patients are symptomatic, reporting symptoms that include chest pain, palpitations, dyspnea, and syncope. Diagnosis is established by the characteristic features on chest X-ray, echocardiogram, chest computed tomography (CT), and/or cardiac magnetic resonance imging (MRI). We present here a case of a 23 year-old-male, who presented to our hospital with complaints of pleuritic chest pain and exertional dyspnea, of a two-week duration. He was physically active and his past history was otherwise insignificant. His chest CT with contrast was interpreted as showing evidence of multiple emboli, predominantly in the left lung, and he was started on a heparin and warfarin therapy. A repeat chest CT with contrast three weeks later showed no significant change from the previous CT scan. Both scans showed that the heart was abnormally rotated to the left side of the chest. An echocardiogram raised the suspicion of congenital absence of the pericardium, with a posteriorly displaced heart. In retrospect, motion artifact on the left lung, attributed to cardiac pulsations and the lack of pericardium, resulted in a CT chest appearance, mimicking findings of pulmonary embolism. The misdiagnosis of pulmonary embolism was attributed to the artifact caused by excessive cardiac motion artifact on the chest CT scan. In non-gated CT angiograms, excessive motion causes an artifact that blurs the pulmonary vessels, reminiscent of a ′seagull′ or a ′boomerang′. Physicians need to be aware of this phenomenon, as well as the characteristic radiological features of this congenital anomaly, to enable them to make a correct diagnosis. PMID:23580923

TU-F-17A-06: Motion Stability and Dosimetric Impact of Spirometer-Based DIBH-RT of Left-Sided Breast Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

McKenzie, E; Yang, W; Burnison, M

2014-06-15

Purpose: Patients undergoing radiotherapy (RT) for left-sided breast cancer have increased risk of coronary artery disease. Deep Inhalation Breath Hold assisted RT (DIBH-RT) is shown to increase the geometric separation of the target area and heart, reducing cardiac radiation dose. The purposes of this study are to use Cine MV portal images to determine the stability of spirometer-guided DIBH-RT and examine the dosimetric cardiopulmonary impact of this technique. Methods: Twenty consecutive patients with left-sided breast cancer were recruited to the IRB-approved study. Free-breathing (FB) and DIBH-CT's were acquired at simulation. Rigid registration of the FB-CT and DIBH-CT was performed usingmore » primarily breast tissue. Treatment plans were created for each FB-CT and DIBH-CT using identical paired tangent fields with field-in-field or electronic compensation techniques. Dosimetric evaluation included mean and maximum (Dmax) doses for the left anterior descending artery (LAD), mean heart dose, and left lung V20. Cine MV portal images were acquired for medial and lateral fields during treatment. Analysis of Cine images involved chest wall segmentation using an algorithm developed in-house. Intra- and inter-fractional chest wall motion were determined through affine registration to the first frame of each Cine. Results: Dose to each cardiac structure evaluated was significantly (p<0.001) reduced with the DIBH plans. Mean heart dose decreased from 2.9(0.9–6.6) to 1.6(0.6–5.3) Gy; mean LAD dose from 16.6(3–43.6) to 7.4(1.7–32.7) Gy; and LAD Dmax from 35.4 (6.1–53) to 18.4(2.5–51.2) Gy. No statistically significant reduction was found for the left lung V20. Average AP and SI median chest wall motion (intrafractional) was 0.1 (SD=0.9) and 0.5 (SD=1.1) mm, respectively. Average AP inter-fractional chest wall motion was 2.0 (SD=1.4) mm. Conclusion: Spirometer-based DIBH treatments of the left breast are reproducible both inter- and intra-fractionally, and provide a statistically and potentially clinically useful dosimetric advantage to cardiac structures.« less

CFD simulation of flow through heart: a perspective review.

PubMed

Khalafvand, S S; Ng, E Y K; Zhong, L

2011-01-01

The heart is an organ which pumps blood around the body by contraction of muscular wall. There is a coupled system in the heart containing the motion of wall and the motion of blood fluid; both motions must be computed simultaneously, which make biological computational fluid dynamics (CFD) difficult. The wall of the heart is not rigid and hence proper boundary conditions are essential for CFD modelling. Fluid-wall interaction is very important for real CFD modelling. There are many assumptions for CFD simulation of the heart that make it far from a real model. A realistic fluid-structure interaction modelling the structure by the finite element method and the fluid flow by CFD use more realistic coupling algorithms. This type of method is very powerful to solve the complex properties of the cardiac structure and the sensitive interaction of fluid and structure. The final goal of heart modelling is to simulate the total heart function by integrating cardiac anatomy, electrical activation, mechanics, metabolism and fluid mechanics together, as in the computational framework.

Incremental value of normal adenosine perfusion cardiac magnetic resonance: Long-term outcome.

PubMed

Sozzi, Fabiola B; Iacuzio, Laura; Civaia, Filippo; Canetta, Ciro; Berthier, Frederic; Rusek, Stephane; Rossi, Philippe; Lombardi, Federico; Dreyfus, Gilles; Dor, Vincent

2015-06-01

The purpose of the study was to determine the long-term prognostic value of normal adenosine stress cardiac magnetic resonance imaging (CMR) in patients referred for evaluation of myocardial ischemia. We reviewed 300 consecutive patients (age 65 ± 11 years, 74% male) with suspected or known coronary disease and normal wall motion who had undergone adenosine stress CMR negative for ischemia and scar. Most patients were at intermediate risk of coronary artery disease. The end points studied were all causes of mortality and major adverse cardiac events, including cardiac death, myocardial infarction, revascularization, and hospitalization for unstable angina. During a mean follow-up of 5.5 years (mean = 5.4 ± 1.1), 16 patients died because of various causes (cardiac death in 5 patients). Three patients had a nonfatal myocardial infarction, 7 patients were hospitalized for revascularization, and 11 were medically treated for unstable angina. The annual cardiac event rate was 1.3% (0.78% in the first 3 years and 1.9% between the fourth and sixth years). The predictors of major adverse cardiac events in a multivariate analysis model were as follows: advanced age (hazard ratio [HR] 1.15, 95% confidence interval [95% CI] 1.02-1.30), diabetes (HR 17.5, 95% CI 2.2-140), and the habit of smoking (HR 5.9, 95% CI 1.0-35.5). For all causes of mortality, the only predictor was diabetes (HR 11.4, 95% CI 1.76-74.2). Patients with normal stress CMR had an excellent outcome during the 3 years after the study. The cardiac event rate was higher between the fourth and sixth years. Over a 5.5-year period, a low event rate and excellent prognosis occurred in patients with normal adenosine stress CMR. Low- to intermediate-risk patients with a normal CMR are at low risk for subsequent cardiac events. Copyright © 2015 Elsevier Inc. All rights reserved.

An evaluation of data-driven motion estimation in comparison to the usage of external-surrogates in cardiac SPECT imaging

PubMed Central

Mukherjee, Joyeeta Mitra; Hutton, Brian F; Johnson, Karen L; Pretorius, P Hendrik; King, Michael A

2014-01-01

Motion estimation methods in single photon emission computed tomography (SPECT) can be classified into methods which depend on just the emission data (data-driven), or those that use some other source of information such as an external surrogate. The surrogate-based methods estimate the motion exhibited externally which may not correlate exactly with the movement of organs inside the body. The accuracy of data-driven strategies on the other hand is affected by the type and timing of motion occurrence during acquisition, the source distribution, and various degrading factors such as attenuation, scatter, and system spatial resolution. The goal of this paper is to investigate the performance of two data-driven motion estimation schemes based on the rigid-body registration of projections of motion-transformed source distributions to the acquired projection data for cardiac SPECT studies. Comparison is also made of six intensity based registration metrics to an external surrogate-based method. In the data-driven schemes, a partially reconstructed heart is used as the initial source distribution. The partially-reconstructed heart has inaccuracies due to limited angle artifacts resulting from using only a part of the SPECT projections acquired while the patient maintained the same pose. The performance of different cost functions in quantifying consistency with the SPECT projection data in the data-driven schemes was compared for clinically realistic patient motion occurring as discrete pose changes, one or two times during acquisition. The six intensity-based metrics studied were mean-squared difference (MSD), mutual information (MI), normalized mutual information (NMI), pattern intensity (PI), normalized cross-correlation (NCC) and entropy of the difference (EDI). Quantitative and qualitative analysis of the performance is reported using Monte-Carlo simulations of a realistic heart phantom including degradation factors such as attenuation, scatter and system spatial resolution. Further the visual appearance of motion-corrected images using data-driven motion estimates was compared to that obtained using the external motion-tracking system in patient studies. Pattern intensity and normalized mutual information cost functions were observed to have the best performance in terms of lowest average position error and stability with degradation of image quality of the partial reconstruction in simulations. In all patients, the visual quality of PI-based estimation was either significantly better or comparable to NMI-based estimation. Best visual quality was obtained with PI-based estimation in 1 of the 5 patient studies, and with external-surrogate based correction in 3 out of 5 patients. In the remaining patient study there was little motion and all methods yielded similar visual image quality. PMID:24107647

SU-E-I-80: Quantification of Respiratory and Cardiac Motion Effect in SPECT Acquisitions Using Anthropomorphic Models: A Monte Carlo Simulation Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Papadimitroulas, P; Kostou, T; Kagadis, G

Purpose: The purpose of the present study was to quantify, evaluate the impact of cardiac and respiratory motion on clinical nuclear imaging protocols. Common SPECT and scintigraphic scans are studied using Monte Carlo (MC) simulations, comparing the resulted images with and without motion. Methods: Realistic simulations were executed using the GATE toolkit and the XCAT anthropomorphic phantom as a reference model for human anatomy. Three different radiopharmaceuticals based on 99mTc were studied, namely 99mTc-MDP, 99mTc—N—DBODC and 99mTc—DTPA-aerosol for bone, myocardium and lung scanning respectively. The resolution of the phantom was set to 3.5 mm{sup 3}. The impact of the motionmore » on spatial resolution was quantified using a sphere with 3.5 mm diameter and 10 separate time frames, in the ECAM modeled SPECT scanner. Finally, respiratory motion impact on resolution and imaging of lung lesions was investigated. The MLEM algorithm was used for data reconstruction, while the literature derived biodistributions of the pharmaceuticals were used as activity maps in the simulations. Results: FWHM was extracted for a static and a moving sphere which was ∼23 cm away from the entrance of the SPECT head. The difference in the FWHM was 20% between the two simulations. Profiles in thorax were compared in the case of bone scintigraphy, showing displacement and blurring of the bones when respiratory motion was inserted in the simulation. Large discrepancies were noticed in the case of myocardium imaging when cardiac motion was incorporated during the SPECT acquisition. Finally the borders of the lungs are blurred when respiratory motion is included resulting to a dislocation of ∼2.5 cm. Conclusion: As we move to individualized imaging and therapy procedures, quantitative and qualitative imaging is of high importance in nuclear diagnosis. MC simulations combined with anthropomorphic digital phantoms can provide an accurate tool for applications like motion correction techniques’ optimization. This research has been co-funded by the European Union (European Social Fund) and Greek national resources under the framework of the ‘Archimedes III: Funding of Research Groups in TEI of Athens’ project of the ‘Education & Lifelong Learning’ Operational Programme.« less

Cardiac Amyloidosis Shows Decreased Diastolic Function as Assessed by Echocardiographic Parameterized Diastolic Filling.

PubMed

Salman, Katrin; Cain, Peter A; Fitzgerald, Benjamin T; Sundqvist, Martin G; Ugander, Martin

2017-07-01

Cardiac amyloidosis is a rare but serious condition with poor survival. One of the early findings by echocardiography is impaired diastolic function, even before the development of cardiac symptoms. Early diagnosis is important, permitting initiation of treatment aimed at improving survival. The parameterized diastolic filling (PDF) formalism entails describing the left ventricular filling pattern during early diastole using the mathematical equation for the motion of a damped harmonic oscillator. We hypothesized that echocardiographic PDF analysis could detect differences in diastolic function between patients with amyloidosis and controls. Pulsed-wave Doppler echocardiography of transmitral flow was measured in 13 patients with amyloid heart disease and 13 age- and gender matched controls. E- waves (2 to 3 per subject) were analyzed using in-house developed software. Nine PDF-derived parameters were obtained in addition to conventional echocardiographic parameters of diastolic function. Compared to controls, cardiac amyloidosis patients had a larger left atrial area (23.7 ± 7.5 cm 2 vs. 18.5 ± 4.8 cm 2 , p = 0.04), greater interventricular septum wall thickness (14.4 ± 2.6 mm vs. 9.3 ± 1.3 mm, p < 0.001), lower e' (0.06 ± 0.02 m/s vs. 0.09 ± 0.02 m/s, p < 0.001) and higher E/e' (18.0 ± 12.9 vs. 7.7 ± 1.3, p = 0.001). The PDF parameter peak resistive force was greater in cardiac amyloidosis patients compared to controls (17.9 ± 5.7 mN vs. 13.1 ± 3.1 mN, p = 0.03), and other PDF parameters did not differ. PDF analysis revealed that patients with cardiac amyloidosis had a greater peak resistive force compared to controls, consistent with a greater degree of diastolic dysfunction. PDF analysis may be useful in characterizing diastolic function in amyloid heart disease. Copyright © 2017 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Dictionary learning-based spatiotemporal regularization for 3D dense speckle tracking

NASA Astrophysics Data System (ADS)

Lu, Allen; Zontak, Maria; Parajuli, Nripesh; Stendahl, John C.; Boutagy, Nabil; Eberle, Melissa; O'Donnell, Matthew; Sinusas, Albert J.; Duncan, James S.

2017-03-01

Speckle tracking is a common method for non-rigid tissue motion analysis in 3D echocardiography, where unique texture patterns are tracked through the cardiac cycle. However, poor tracking often occurs due to inherent ultrasound issues, such as image artifacts and speckle decorrelation; thus regularization is required. Various methods, such as optical flow, elastic registration, and block matching techniques have been proposed to track speckle motion. Such methods typically apply spatial and temporal regularization in a separate manner. In this paper, we propose a joint spatiotemporal regularization method based on an adaptive dictionary representation of the dense 3D+time Lagrangian motion field. Sparse dictionaries have good signal adaptive and noise-reduction properties; however, they are prone to quantization errors. Our method takes advantage of the desirable noise suppression, while avoiding the undesirable quantization error. The idea is to enforce regularization only on the poorly tracked trajectories. Specifically, our method 1.) builds data-driven 4-dimensional dictionary of Lagrangian displacements using sparse learning, 2.) automatically identifies poorly tracked trajectories (outliers) based on sparse reconstruction errors, and 3.) performs sparse reconstruction of the outliers only. Our approach can be applied on dense Lagrangian motion fields calculated by any method. We demonstrate the effectiveness of our approach on a baseline block matching speckle tracking and evaluate performance of the proposed algorithm using tracking and strain accuracy analysis.

Fully automated registration of first-pass myocardial perfusion MRI using independent component analysis.

PubMed

Milles, J; van der Geest, R J; Jerosch-Herold, M; Reiber, J H C; Lelieveldt, B P F

2007-01-01

This paper presents a novel method for registration of cardiac perfusion MRI. The presented method successfully corrects for breathing motion without any manual interaction using Independent Component Analysis to extract physiologically relevant features together with their time-intensity behavior. A time-varying reference image mimicking intensity changes in the data of interest is computed based on the results of ICA, and used to compute the displacement caused by breathing for each frame. Qualitative and quantitative validation of the method is carried out using 46 clinical quality, short-axis, perfusion MR datasets comprising 100 images each. Validation experiments showed a reduction of the average LV motion from 1.26+/-0.87 to 0.64+/-0.46 pixels. Time-intensity curves are also improved after registration with an average error reduced from 2.65+/-7.89% to 0.87+/-3.88% between registered data and manual gold standard. We conclude that this fully automatic ICA-based method shows an excellent accuracy, robustness and computation speed, adequate for use in a clinical environment.

Towards an interactive electromechanical model of the heart

PubMed Central

Talbot, Hugo; Marchesseau, Stéphanie; Duriez, Christian; Sermesant, Maxime; Cotin, Stéphane; Delingette, Hervé

2013-01-01

In this work, we develop an interactive framework for rehearsal of and training in cardiac catheter ablation, and for planning cardiac resynchronization therapy. To this end, an interactive and real-time electrophysiology model of the heart is developed to fit patient-specific data. The proposed interactive framework relies on two main contributions. First, an efficient implementation of cardiac electrophysiology is proposed, using the latest graphics processing unit computing techniques. Second, a mechanical simulation is then coupled to the electrophysiological signals to produce realistic motion of the heart. We demonstrate that pathological mechanical and electrophysiological behaviour can be simulated. PMID:24427533

Dynamic heart model for the mathematical cardiac torso (MCAT) phantom to represent the invariant total heart volume

NASA Astrophysics Data System (ADS)

Pretorius, P. H.; King, Michael A.; Tsui, Benjamin M.; LaCroix, Karen; Xia, Weishi

1998-07-01

This manuscript documents the alteration of the heart model of the MCAT phantom to better represent cardiac motion. The objective of the inclusion of motion was to develop a digital simulation of the heart such that the impact of cardiac motion on single photon emission computed tomography (SPECT) imaging could be assessed and methods of quantitating cardiac function could be investigated. The motion of the dynamic MCAT's heart is modeled by a 128 time frame volume curve. Eight time frames are averaged together to obtain a gated perfusion acquisition of 16 time frames and ensure motion within every time frame. The position of the MCAT heart was changed during contraction to rotate back and forth around the long axis through the center of the left ventricle (LV) using the end systolic time frame as turning point. Simple respiratory motion was also introduced by changing the orientation of the heart model in a 2 dimensional (2D) plane with every time frame. The averaging effect of respiratory motion in a specific time frame was modeled by randomly selecting multiple heart locations between two extreme orientations. Non-gated perfusion phantoms were also generated by averaging over all time frames. Maximal chamber volumes were selected to fit a profile of a normal healthy person. These volumes were changed during contraction of the ventricles such that the increase in volume in the atria compensated for the decrease in volume in the ventricles. The myocardium were modeled to represent shortening of muscle fibers during contraction with the base of the ventricles moving towards a static apex. The apical region was modeled with moderate wall thinning present while myocardial mass was conserved. To test the applicability of the dynamic heart model, myocardial wall thickening was measured using maximum counts and full width half maximum measurements, and compared with published trends. An analytical 3D projector, with attenuation and detector response included, was used to generate radionuclide projection data sets. After reconstruction a linear relationship was obtained between maximum myocardial counts and myocardium thickness, similar to published results. A numeric difference in values from different locations exist due to different amounts of attenuation present. Similar results were obtained for FWHM measurements. Also, a hot apical region on the polar maps without attenuation compensation turns into an apical defect with attenuation compensation. The apical decrease was more prominent in ED than ES due to the change in the partial volume effect. Both of these agree with clinical trends. It is concluded that the dynamic MCAT (dMCAT) phantom can be used to study the influence of various physical parameters on radionuclide perfusion imaging.

High-Resolution Tissue Doppler Imaging of the Zebrafish Heart During Its Regeneration

PubMed Central

Su, Ta-Han; Shih, Cho-Chiang

2015-01-01

Abstract The human heart cannot regenerate after injury, whereas the adult zebrafish can fully regenerate its heart even after 20% of the ventricle is amputated. Many studies have begun to reveal the cellular and molecular mechanisms underlying this regenerative process, which have exciting implications for human cardiac diseases. However, the dynamic functions of the zebrafish heart during regeneration are not yet understood. This study established a high-resolution echocardiography for tissue Doppler imaging (TDI) of the zebrafish heart to explore the cardiac functions during different regeneration phases. Experiments were performed on AB-line adult zebrafish (n=40) in which 15% of the ventricle was surgically removed. An 80-MHz ultrasound TDI based on color M-mode imaging technology was employed. The cardiac flow velocities and patterns from both the ventricular chamber and myocardium were measured at different regeneration phases relative to the day of amputation. The peak velocities of early diastolic inflow, early diastolic myocardial motion, late diastolic myocardial motion, early diastolic deceleration slope, and heart rate were increased at 3 days after the myocardium amputation, but these parameters gradually returned to close to their baseline values for the normal heart at 7 days after amputation. The peak velocities of late diastolic inflow, ventricular systolic outflow, and systolic myocardial motion did not significantly differ during the heart regeneration. PMID:25517185

Fetal cardiac cine imaging using highly accelerated dynamic MRI with retrospective motion correction and outlier rejection

PubMed Central

Lloyd, David F.A.; Price, Anthony N.; Kuklisova Murgasova, Maria; Aljabar, Paul; Malik, Shaihan J.; Lohezic, Maelene; Rutherford, Mary A.; Pushparajah, Kuberan; Razavi, Reza; Hajnal, Joseph V.

2017-01-01

Purpose Development of a MRI acquisition and reconstruction strategy to depict fetal cardiac anatomy in the presence of maternal and fetal motion. Methods The proposed strategy involves i) acquisition and reconstruction of highly accelerated dynamic MRI, followed by image‐based ii) cardiac synchronization, iii) motion correction, iv) outlier rejection, and finally v) cardiac cine reconstruction. Postprocessing entirely was automated, aside from a user‐defined region of interest delineating the fetal heart. The method was evaluated in 30 mid‐ to late gestational age singleton pregnancies scanned without maternal breath‐hold. Results The combination of complementary acquisition/reconstruction and correction/rejection steps in the pipeline served to improve the quality of the reconstructed 2D cine images, resulting in increased visibility of small, dynamic anatomical features. Artifact‐free cine images successfully were produced in 36 of 39 acquired data sets; prolonged general fetal movements precluded processing of the remaining three data sets. Conclusions The proposed method shows promise as a motion‐tolerant framework to enable further detail in MRI studies of the fetal heart and great vessels. Processing data in image‐space allowed for spatial and temporal operations to be applied to the fetal heart in isolation, separate from extraneous changes elsewhere in the field of view. Magn Reson Med 79:327–338, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. PMID:28370252

Self-gated golden-angle spiral 4D flow MRI.

PubMed

Bastkowski, Rene; Weiss, Kilian; Maintz, David; Giese, Daniel

2018-01-17

The acquisition of 4D flow magnetic resonance imaging (MRI) in cardiovascular applications has recently made large progress toward clinical feasibility. The need for simultaneous compensation of cardiac and breathing motion still poses a challenge for widespread clinical use. Especially, breathing motion, addressed by gating approaches, can lead to unpredictable and long scan times. The current work proposes a time-efficient self-gated 4D flow sequence that exploits up to 100% of the acquired data and operates at a predictable scan time. A self-gated golden-angle spiral 4D flow sequence was implemented and tested in 10 volunteers. Data were retrospectively binned into respiratory and cardiac states and reconstructed using a conjugate-gradient sensitivity encoding reconstruction. Net flow curves, stroke volumes, and peak flow in the aorta were evaluated and compared to a conventional Cartesian 4D flow sequence. Additionally, flow quantities reconstructed from 50% to 100% of the self-gated 4D flow data were compared. Self-gating signals for respiratory and cardiac motion were extracted for all volunteers. Flow quantities were in agreement with the standard Cartesian scan. Mean differences in stroke volumes and peak flow of 7.6 ± 11.5 and 4.0 ± 79.9 mL/s were obtained, respectively. By retrospectively increasing breathing navigator efficiency while decreasing acquisition times (15:06-07:33 minutes), 50% of the acquired data were sufficient to measure stroke volumes with errors under 9.6 mL. The feasibility to acquire respiratory and cardiac self-gated 4D flow data at a predictable scan time was demonstrated. Magn Reson Med, 2018. © 2018 International Society for Magnetic Resonance in Medicine. © 2018 International Society for Magnetic Resonance in Medicine.

Correction of motion artifacts in OCT-AFI data collected in airways (Conference Presentation)

NASA Astrophysics Data System (ADS)

Abouei, Elham; Lane, Pierre M.; Pahlevaninezhad, Hamid; Lee, Anthony; Lam, Stephen; MacAulay, Calum E.

2016-03-01

Abstract: Optical coherence tomography (OCT) provides in vivo imaging with near-histologic resolution of tissue morphology. OCT has been successfully employed in clinical practice in non-pulmonary fields of medicine such as ophthalmology and cardiology. Studies suggest that OCT has the potential to be a powerful tool for the detection and localization of malignant and non-malignant pulmonary diseases. The combination of OCT with autofluorescence imaging (AFI) provides valuable information about the structural and metabolic state of tissues. Successful application of OCT or OCT-AFI to the field of pulmonary medicine requires overcoming several challenges. This work address those associated with motion: cardiac cycle, breathing and non-uniform rotation distortion (NURD) artifacts. Mechanically rotated endoscopic probes often suffer from image degradation due to NURD. In addition cardiac and breathing motion artifacts may be present in-vivo that are not seen ex-vivo. These motion artifacts can be problematic in OCT-AFI systems with slower acquisition rates and have been observed to generate identifiable prominent artifacts which make confident interpretation of observed structures (blood vessels, etc) difficult. Understanding and correcting motion artifact could improve the image quality and interpretation. In this work, the motion artifacts in pulmonary OCT-AFI data sets are estimated in both AFI and OCT images using a locally adaptive registration algorithm that can be used to correct/reduce such artifacts. Performance of the algorithm is evaluated on images of a NURD phantom and on in-vivo OCT-AFI datasets of peripheral lung airways.

AFFINE-CORRECTED PARADISE: FREE-BREATHING PATIENT-ADAPTIVE CARDIAC MRI WITH SENSITIVITY ENCODING

PubMed Central

Sharif, Behzad; Bresler, Yoram

2013-01-01

We propose a real-time cardiac imaging method with parallel MRI that allows for free breathing during imaging and does not require cardiac or respiratory gating. The method is based on the recently proposed PARADISE (Patient-Adaptive Reconstruction and Acquisition Dynamic Imaging with Sensitivity Encoding) scheme. The new acquisition method adapts the PARADISE k-t space sampling pattern according to an affine model of the respiratory motion. The reconstruction scheme involves multi-channel time-sequential imaging with time-varying channels. All model parameters are adapted to the imaged patient as part of the experiment and drive both data acquisition and cine reconstruction. Simulated cardiac MRI experiments using the realistic NCAT phantom show high quality cine reconstructions and robustness to modeling inaccuracies. PMID:24390159

Optical Mapping of Membrane Potential and Epicardial Deformation in Beating Hearts.

PubMed

Zhang, Hanyu; Iijima, Kenichi; Huang, Jian; Walcott, Gregory P; Rogers, Jack M

2016-07-26

Cardiac optical mapping uses potentiometric fluorescent dyes to image membrane potential (Vm). An important limitation of conventional optical mapping is that contraction is usually arrested pharmacologically to prevent motion artifacts from obscuring Vm signals. However, these agents may alter electrophysiology, and by abolishing contraction, also prevent optical mapping from being used to study coupling between electrical and mechanical function. Here, we present a method to simultaneously map Vm and epicardial contraction in the beating heart. Isolated perfused swine hearts were stained with di-4-ANEPPS and fiducial markers were glued to the epicardium for motion tracking. The heart was imaged at 750 Hz with a video camera. Fluorescence was excited with cyan or blue LEDs on alternating camera frames, thus providing a 375-Hz effective sampling rate. Marker tracking enabled the pixel(s) imaging any epicardial site within the marked region to be identified in each camera frame. Cyan- and blue-elicited fluorescence have different sensitivities to Vm, but other signal features, primarily motion artifacts, are common. Thus, taking the ratio of fluorescence emitted by a motion-tracked epicardial site in adjacent frames removes artifacts, leaving Vm (excitation ratiometry). Reconstructed Vm signals were validated by comparison to monophasic action potentials and to conventional optical mapping signals. Binocular imaging with additional video cameras enabled marker motion to be tracked in three dimensions. From these data, epicardial deformation during the cardiac cycle was quantified by computing finite strain fields. We show that the method can simultaneously map Vm and strain in a left-sided working heart preparation and can image changes in both electrical and mechanical function 5 min after the induction of regional ischemia. By allowing high-resolution optical mapping in the absence of electromechanical uncoupling agents, the method relieves a long-standing limitation of optical mapping and has potential to enhance new studies in coupled cardiac electromechanics. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Mass emergency water-based foam depopulation of poultry.

PubMed

Benson, E R; Alphin, R L; Rankin, M K; Caputo, M P; Hougentogler, D P; Johnson, A L

2012-12-01

When an avian influenza or virulent Newcastle disease outbreak occurs within commercial poultry, a large number of birds that are infected or suspected of infection must be destroyed on site to prevent the rapid spread of disease. The choice of mass emergency depopulation procedures is limited, and all options have limitations. Water-based foam mass emergency depopulation of poultry was developed in 2006 and conditionally approved by the U.S. Department of Agriculture and American Veterinary Medical Association. Water-based foam causes mechanical hypoxia and can be used for broilers, layers, turkeys, and ducks. The time to physiologic states was evaluated for broilers, layer hens, turkeys, and ducks, comparing water-based foam and CO2 gas using electroencephalogram (unconsciousness and brain death), electrocardiogram (altered terminal cardiac activity), and accelerometer (motion cessation). In broilers, turkeys, and layer hens, water-based foam results in equivalent times to unconsciousness, terminal convulsions, and altered terminal cardiac activity. With Pekin ducks, however, CO2 gas resulted in shorter times to key physiologic states, in particular unconsciousness, altered terminal cardiac activity, motion cessation, and brain death.

Relationship of gastric myoelectrical and cardiac parasympathetic activity to chemotherapy-induced nausea

PubMed Central

Gianaros, Peter J.; Stern, Robert M.; Morrow, Gary R.; Hickok, Jane T.

2010-01-01

Objectives We evaluated (a) whether pretreatment levels of gastric tachyarrhythmia, a dysrhythmic pattern of gastric myoelectrical activity, or cardiac parasympathetic activity are associated with the development of chemotherapy-induced nausea and (b) whether chemotherapy-induced nausea is preceded by an increase in gastric tachyarrhythmia and a decrease in cardiac parasympathetic activity, as has been observed during motion sickness. Methods Electrogastrograms and estimates of respiratory sinus arrhythmia (RSA) were obtained from cancer chemotherapy patients before treatment and for approximately 24 hours after treatment. Results Higher levels of pretreatment gastric tachyarrhythmia were observed on chemotherapy sessions that were followed by posttreatment reports of nausea. Pretreatment levels of RSA, however, did not differ between chemotherapy treatments that were and were not followed by nausea. No statistically significant changes in gastric tachyarrhythmia or RSA were observed prior to first reports of nausea following chemotherapy. Conclusions In contrast to motion sickness, chemotherapy-induced nausea may not be related to an increase in dysrhythmic gastric myoelectrical activity; however, higher levels of pretreatment gastric tachyarrhythmia may be related to posttreatment reports of chemotherapy-induced nausea. PMID:11399283

OCT-based angiography in real time with hand-held probe

NASA Astrophysics Data System (ADS)

Gelikonov, Grigory V.; Moiseev, Alexander A.; Ksenofontov, Sergey Y.; Terpelov, Dmitry A.; Gelikonov, Valentine M.

2018-03-01

This work is dedicated to development of the OCT system capable to visualize blood vessel network for everyday clinical use. Following problems were solved during the development: compensation of specific natural tissue displacements, induced by contact scanning mode and physiological motion of patients (e.g. respiratory and cardiac motions) and on-line visualization of vessel net to provide the feedback for system operator.

A combination of spatial and recursive temporal filtering for noise reduction when using region of interest (ROI) fluoroscopy for patient dose reduction in image guided vascular interventions with significant anatomical motion

NASA Astrophysics Data System (ADS)

Setlur Nagesh, S. V.; Khobragade, P.; Ionita, C.; Bednarek, D. R.; Rudin, S.

2015-03-01

Because x-ray based image-guided vascular interventions are minimally invasive they are currently the most preferred method of treating disorders such as stroke, arterial stenosis, and aneurysms; however, the x-ray exposure to the patient during long image-guided interventional procedures could cause harmful effects such as cancer in the long run and even tissue damage in the short term. ROI fluoroscopy reduces patient dose by differentially attenuating the incident x-rays outside the region-of-interest. To reduce the noise in the dose-reduced regions previously recursive temporal filtering was successfully demonstrated for neurovascular interventions. However, in cardiac interventions, anatomical motion is significant and excessive recursive filtering could cause blur. In this work the effects of three noise-reduction schemes, including recursive temporal filtering, spatial mean filtering, and a combination of spatial and recursive temporal filtering, were investigated in a simulated ROI dose-reduced cardiac intervention. First a model to simulate the aortic arch and its movement was built. A coronary stent was used to simulate a bioprosthetic valve used in TAVR procedures and was deployed under dose-reduced ROI fluoroscopy during the simulated heart motion. The images were then retrospectively processed for noise reduction in the periphery, using recursive temporal filtering, spatial filtering and a combination of both. Quantitative metrics for all three noise reduction schemes are calculated and are presented as results. From these it can be concluded that with significant anatomical motion, a combination of spatial and recursive temporal filtering scheme is best suited for reducing the excess quantum noise in the periphery. This new noise-reduction technique in combination with ROI fluoroscopy has the potential for substantial patient-dose savings in cardiac interventions.

Three-dimensional ballistocardiography and respiratory motion in sustained microgravity

NASA Technical Reports Server (NTRS)

Prisk, G. K.; Verhaeghe, S.; Padeken, D.; Hamacher, H.; Paiva, M.; West, J. B. (Principal Investigator)

2001-01-01

BACKGROUND: We measured the three-dimensional ballistocardiogram (BCG) in a free-floating subject in sustained microgravity during spaceflight to test the usefulness of such measurements for future non-invasive monitoring of cardiac function, and to examine the effects of respiratory movement on the BCG in three axes. METHODS: Acceleration was measured using a three-axis accelerometer fastened to the lumbar region of the subject while simultaneous recordings of ECG, and respiratory motion via impedance plethysmography were also made. Data were recorded during a 146-s period of inactivity on the part of the subject during which time there was no contact with the spacecraft. RESULTS: Total body motion due to respiratory activity was consistent with that calculated from the known action of the diaphragm and conservation of momentum. The accelerations due to cardiac activity, ensemble averaged over the R-R interval, were greatest along the head-to-foot axis. Maximum amplitude of the HIJK complex of the BCG generated by ventricular ejection was greatest in the head to foot axis (approximately 70 x 10(-3) m x s(-2)), but there were also substantial accelerations along the dorsoventral axis of up to 43 10(-3) m x s(-2), that are not measured interrestrial two-dimensional studies. The amplitude of the BCG was strongly affected by lung volume, with accelerations being reduced 50 to 70% between end-inspiration and end-expiration. CONCLUSIONS: These data suggest a greatly reduced transmission of the cardiac motion to the body at end-expiration (FRC) than at higher lung volumes. The BCG might be further developed as a non-invasive means of monitoring parameters such as stroke volume in microgravity.

A comparison study: image-based vs signal-based retrospective gating on microCT

NASA Astrophysics Data System (ADS)

Liu, Xuan; Salmon, Phil L.; Laperre, Kjell; Sasov, Alexander

2017-09-01

Retrospective gating on animal studies with microCT has gained popularity in recent years. Previously, we use ECG signals for cardiac gating and breathing airflow or video signals of abdominal motion for respiratory gating. This method is adequate and works well for most applications. However, through the years, researchers have noticed some pitfalls in the method. For example, the additional signal acquisition step may increase failure rate in practice. X-Ray image-based gating, on the other hand, does not require any extra step in the scanning. Therefore we investigate imagebased gating techniques. This paper presents a comparison study of the image-based versus signal-based approach to retrospective gating. The two application areas we have studied are respiratory and cardiac imaging for both rats and mice. Image-based respiratory gating on microCT is relatively straightforward and has been done by several other researchers and groups. This method retrieves an intensity curve of a region of interest (ROI) placed in the lung area on all projections. From scans on our systems based on step-and-shoot scanning mode, we confirm that this method is very effective. A detailed comparison between image-based and signal-based gating methods is given. For cardiac gating, breathing motion is not negligible and has to be dealt with. Another difficulty in cardiac gating is the relatively smaller amplitude of cardiac movements comparing to the respirational movements, and the higher heart rate. Higher heart rate requires high speed image acquisition. We have been working on our systems to improve the acquisition speed. A dual gating technique has been developed to achieve adequate cardiac imaging.

Evaluation of interpolation methods for surface-based motion compensated tomographic reconstruction for cardiac angiographic C-arm data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mueller, Kerstin; Schwemmer, Chris; Hornegger, Joachim

2013-03-15

Purpose: For interventional cardiac procedures, anatomical and functional information about the cardiac chambers is of major interest. With the technology of angiographic C-arm systems it is possible to reconstruct intraprocedural three-dimensional (3D) images from 2D rotational angiographic projection data (C-arm CT). However, 3D reconstruction of a dynamic object is a fundamental problem in C-arm CT reconstruction. The 2D projections are acquired over a scan time of several seconds, thus the projection data show different states of the heart. A standard FDK reconstruction algorithm would use all acquired data for a filtered backprojection and result in a motion-blurred image. In thismore » approach, a motion compensated reconstruction algorithm requiring knowledge of the 3D heart motion is used. The motion is estimated from a previously presented 3D dynamic surface model. This dynamic surface model results in a sparse motion vector field (MVF) defined at control points. In order to perform a motion compensated reconstruction, a dense motion vector field is required. The dense MVF is generated by interpolation of the sparse MVF. Therefore, the influence of different motion interpolation methods on the reconstructed image quality is evaluated. Methods: Four different interpolation methods, thin-plate splines (TPS), Shepard's method, a smoothed weighting function, and a simple averaging, were evaluated. The reconstruction quality was measured on phantom data, a porcine model as well as on in vivo clinical data sets. As a quality index, the 2D overlap of the forward projected motion compensated reconstructed ventricle and the segmented 2D ventricle blood pool was quantitatively measured with the Dice similarity coefficient and the mean deviation between extracted ventricle contours. For the phantom data set, the normalized root mean square error (nRMSE) and the universal quality index (UQI) were also evaluated in 3D image space. Results: The quantitative evaluation of all experiments showed that TPS interpolation provided the best results. The quantitative results in the phantom experiments showed comparable nRMSE of Almost-Equal-To 0.047 {+-} 0.004 for the TPS and Shepard's method. Only slightly inferior results for the smoothed weighting function and the linear approach were achieved. The UQI resulted in a value of Almost-Equal-To 99% for all four interpolation methods. On clinical human data sets, the best results were clearly obtained with the TPS interpolation. The mean contour deviation between the TPS reconstruction and the standard FDK reconstruction improved in the three human cases by 1.52, 1.34, and 1.55 mm. The Dice coefficient showed less sensitivity with respect to variations in the ventricle boundary. Conclusions: In this work, the influence of different motion interpolation methods on left ventricle motion compensated tomographic reconstructions was investigated. The best quantitative reconstruction results of a phantom, a porcine, and human clinical data sets were achieved with the TPS approach. In general, the framework of motion estimation using a surface model and motion interpolation to a dense MVF provides the ability for tomographic reconstruction using a motion compensation technique.« less

Noninvasive iPhone Measurement of Left Ventricular Ejection Fraction Using Intrinsic Frequency Methodology.

PubMed

Pahlevan, Niema M; Rinderknecht, Derek G; Tavallali, Peyman; Razavi, Marianne; Tran, Thao T; Fong, Michael W; Kloner, Robert A; Csete, Marie; Gharib, Morteza

2017-07-01

The study is based on previously reported mathematical analysis of arterial waveform that extracts hidden oscillations in the waveform that we called intrinsic frequencies. The goal of this clinical study was to compare the accuracy of left ventricular ejection fraction derived from intrinsic frequencies noninvasively versus left ventricular ejection fraction obtained with cardiac MRI, the most accurate method for left ventricular ejection fraction measurement. After informed consent, in one visit, subjects underwent cardiac MRI examination and noninvasive capture of a carotid waveform using an iPhone camera (The waveform is captured using a custom app that constructs the waveform from skin displacement images during the cardiac cycle.). The waveform was analyzed using intrinsic frequency algorithm. Outpatient MRI facility. Adults able to undergo MRI were referred by local physicians or self-referred in response to local advertisement and included patients with heart failure with reduced ejection fraction diagnosed by a cardiologist. Standard cardiac MRI sequences were used, with periodic breath holding for image stabilization. To minimize motion artifact, the iPhone camera was held in a cradle over the carotid artery during iPhone measurements. Regardless of neck morphology, carotid waveforms were captured in all subjects, within seconds to minutes. Seventy-two patients were studied, ranging in age from 20 to 92 years old. The main endpoint of analysis was left ventricular ejection fraction; overall, the correlation between ejection fraction-iPhone and ejection fraction-MRI was 0.74 (r = 0.74; p < 0.0001; ejection fraction-MRI = 0.93 × [ejection fraction-iPhone] + 1.9). Analysis of carotid waveforms using intrinsic frequency methods can be used to document left ventricular ejection fraction with accuracy comparable with that of MRI. The measurements require no training to perform or interpret, no calibration, and can be repeated at the bedside to generate almost continuous analysis of left ventricular ejection fraction without arterial cannulation.

In vivo imaging of cardiac development and function in zebrafish using light sheet microscopy.

PubMed

Weber, Michael; Huisken, Jan

2015-01-01

Detailed studies of heart development and function are crucial for our understanding of cardiac failures and pave the way for better diagnostics and treatment. However, the constant motion and close incorporation into the cardiovascular system prevent in vivo studies of the living, unperturbed heart. The complementary strengths of the zebrafish model and light sheet microscopy provide a useful platform to fill this gap. High-resolution images of the embryonic vertebrate heart are now recorded from within the living animal: deep inside the unperturbed heart we can follow cardiac contractions and measure action potentials and calcium transients. Three-dimensional reconstructions of the entire beating heart with cellular resolution give new insights into its ever-changing morphology and facilitate studies into how individual cells form the complex cardiac network. In addition, cardiac dynamics and robustness are now examined with targeted optical manipulation. Overall, the combination of zebrafish and light sheet microscopy represents a promising addition for cardiac research and opens the door to a better understanding of heart function and development.

Cardiac elastography: detecting pathological changes in myocardium tissues

NASA Astrophysics Data System (ADS)

Konofagou, Elisa E.; Harrigan, Timothy; Solomon, Scott

2003-05-01

Estimation of the mechanical properties of the cardiac muscle has been shown to play a crucial role in the detection of cardiovascular disease. Elastography was recently shown feasible on RF cardiac data in vivo. In this paper, the role of elastography in the detection of ischemia/infarct is explored with simulations and in vivo experiments. In finite-element simulations of a portion of the cardiac muscle containing an infarcted region, the cardiac cycle was simulated with successive compressive and tensile strains ranging between -30% and 20%. The incremental elastic modulus was also mapped uisng adaptive methods. We then demonstrated this technique utilizing envelope-detected sonographic data (Hewlett-Packard Sonos 5500) in a patient with a known myocardial infarction. In cine-loop and M-Mode elastograms from both normal and infarcted regions in simulations and experiments, the infarcted region was identifed by the up to one order of magnitude lower incremental axial displacements and strains, and higher modulus. Information on motion, deformation and mechanical property should constitute a unique tool for noninvasive cardiac diagnosis.

Local motion-compensated method for high-quality 3D coronary artery reconstruction

PubMed Central

Liu, Bo; Bai, Xiangzhi; Zhou, Fugen

2016-01-01

The 3D reconstruction of coronary artery from X-ray angiograms rotationally acquired on C-arm has great clinical value. While cardiac-gated reconstruction has shown promising results, it suffers from the problem of residual motion. This work proposed a new local motion-compensated reconstruction method to handle this issue. An initial image was firstly reconstructed using a regularized iterative reconstruction method. Then a 3D/2D registration method was proposed to estimate the residual vessel motion. Finally, the residual motion was compensated in the final reconstruction using the extended iterative reconstruction method. Through quantitative evaluation, it was found that high-quality 3D reconstruction could be obtained and the result was comparable to state-of-the-art method. PMID:28018741

Medical applications of shortwave FM radar: remote monitoring of cardiac and respiratory motion.

PubMed

Mostov, K; Liptsen, E; Boutchko, R

2010-03-01

This article introduces the use of low power continuous wave frequency modulated radar for medical applications, specifically for remote monitoring of vital signs in patients. Gigahertz frequency radar measures the electromagnetic wave signal reflected from the surface of a human body and from tissue boundaries. Time series analysis of the measured signal provides simultaneous information on range, size, and reflective properties of multiple targets in the field of view of the radar. This information is used to extract the respiratory and cardiac rates of the patient in real time. The results from several preliminary human subject experiments are provided. The heart and respiration rate frequencies extracted from the radar signal match those measured independently for all the experiments, including a case when additional targets are simultaneously resolved in the field of view and a case when only the patient's extremity is visible to the radar antennas. Micropower continuous wave FM radar is a reliable, robust, inexpensive, and harmless tool for real-time monitoring of the cardiac and respiratory rates. Additionally, it opens a range of new and exciting opportunities in diagnostic and critical care medicine. Differences between the presented approach and other types of radars used for biomedical applications are discussed.

Dobutamine stress MRI. Part I. Safety and feasibility of dobutamine cardiovascular magnetic resonance in patients suspected of myocardial ischemia.

PubMed

Kuijpers, Dirkjan; Janssen, Caroline H C; van Dijkman, Paul R M; Oudkerk, Matthijs

2004-10-01

The aim of the study was to evaluate safety and feasibility of dobutamine cardiovascular magnetic resonance (CMR) in patients with proven or suspected coronary artery disease. Dobutamine CMR was evaluated retrospectively in 400 consecutive patients with suspicion of myocardial ischemia. Dobutamine was infused using an incremental protocol up to 40 microg/kg body weight per minute. All anti-anginal medication was stopped 4 days before the CMR study and infusion time of dobutamine was 6 min per stage. Hemodynamic data, CMR findings and side effects were reported. Patients with contraindications to CMR (metallic implants and claustrophobia) were excluded from analysis. Dobutamine CMR was successfully performed in 355 (89%) patients. Forty-five (11%) patients could not be investigated adequately because of non-cardiac side effects in 29 (7%) and cardiac side effects in 16 (4%) patients. Hypotension (1.5%) and arrhythmias (1%) were the most frequent cardiac side effects. One patient developed a severe complication (ventricular fibrillation) at the end of the study. There were no myocardial infarctions or fatal complications of the stress test. The most frequent non-cardiac side effects were nausea, vomiting and claustrophobia. Age >70 years, prior myocardial infarction and rest wall motion abnormalities showed no significant differences with side effects (P>0.05). Dobutamine CMR is safe and feasible in patients with suspicion of myocardial ischemia. Copyright 2004 Springer-Verlag

Non-Water-Suppressed 1H MR Spectroscopy with Orientational Prior Knowledge Shows Potential for Separating Intra- and Extramyocellular Lipid Signals in Human Myocardium.

PubMed

Fillmer, Ariane; Hock, Andreas; Cameron, Donnie; Henning, Anke

2017-12-04

Conditions such as type II diabetes are linked with elevated lipid levels in the heart, and significantly increased risk of heart failure; however, metabolic processes underlying the development of cardiac disease in type II diabetes are not fully understood. Here we present a non-invasive method for in vivo investigation of cardiac lipid metabolism: namely, IVS-McPRESS. This technique uses metabolite-cycled, non-water suppressed 1 H cardiac magnetic resonance spectroscopy with prospective and retrospective motion correction. High-quality IVS-McPRESS data acquired from healthy volunteers allowed us to investigate the frequency shift of extramyocellular lipid signals, which depends on the myocardial fibre orientation. Assuming consistent voxel positioning relative to myofibres, the myofibre angle with the magnetic field was derived from the voxel orientation. For separation and individual analysis of intra- and extramyocellular lipid signals, the angle myocardial fibres in the spectroscopy voxel take with the magnetic field should be within ±24.5°. Metabolite and lipid concentrations were analysed with respect to BMI. Significant correlations between BMI and unsaturated fatty acids in intramyocellular lipids, and methylene groups in extramyocellular lipids were found. The proposed IVS-McPRESS technique enables non-invasive investigation of cardiac lipid metabolism and may thus be a useful tool to study healthy and pathological conditions.

The characterisation of blood rotation in a human heart chamber based on statistical analysis of vorticity maps

NASA Astrophysics Data System (ADS)

Wong, Kelvin K. L.; Kelso, Richard M.; Worthley, Stephen G.; Sanders, Prashanthan; Mazumdar, Jagannath; Abbott, Derek

2008-12-01

Modelling of non-stationary cardiac structures is complicated by the complexity of their intrinsic and extrinsic motion. The first known study of haemodynamics due to the beating of heart was made by Leonardo Da Vinci, giving the idea of fluid-solid interaction by describing how vortices develop during cardiac structural interaction with the blood. Heart morphology affects in changes of cardio dynamics during the systolic and diastolic phrases. In a chamber of the heart, vortices are discovered to exist as the result of the unique morphological changes of the cardiac chamber wall by using flow-imaging techniques such as phase contrast magnetic resonance imaging. The first part of this paper attempts to quantify vortex characteristics by means of calculating vorticity numerically and devising two dimensional vortical flow maps. The technique relies on determining the properties of vorticity using a statistical quantification of the flow maps and comparison of these quantities based on different scenarios. As the characteristics of our vorticity maps vary depending on the phase of a cardiac cycle, there is a need for robust quantification method to analyse vorticity. In the second part of the paper, the approach is then utilised for examining vortices within the human right atrium. Our study has shown that a proper quantification of vorticity for the flow field can indicate the strength and number of vortices within a heart chamber.

Digital anthropomorphic phantoms of non-rigid human respiratory and voluntary body motion for investigating motion correction in emission imaging

NASA Astrophysics Data System (ADS)

Könik, Arda; Connolly, Caitlin M.; Johnson, Karen L.; Dasari, Paul; Segars, Paul W.; Pretorius, P. H.; Lindsay, Clifford; Dey, Joyoni; King, Michael A.

2014-07-01

The development of methods for correcting patient motion in emission tomography has been receiving increased attention. Often the performance of these methods is evaluated through simulations using digital anthropomorphic phantoms, such as the commonly used extended cardiac torso (XCAT) phantom, which models both respiratory and cardiac motion based on human studies. However, non-rigid body motion, which is frequently seen in clinical studies, is not present in the standard XCAT phantom. In addition, respiratory motion in the standard phantom is limited to a single generic trend. In this work, to obtain a more realistic representation of motion, we developed a series of individual-specific XCAT phantoms, modeling non-rigid respiratory and non-rigid body motions derived from the magnetic resonance imaging (MRI) acquisitions of volunteers. Acquisitions were performed in the sagittal orientation using the Navigator methodology. Baseline (no motion) acquisitions at end-expiration were obtained at the beginning of each imaging session for each volunteer. For the body motion studies, MRI was again acquired only at end-expiration for five body motion poses (shoulder stretch, shoulder twist, lateral bend, side roll, and axial slide). For the respiratory motion studies, an MRI was acquired during free/regular breathing. The magnetic resonance slices were then retrospectively sorted into 14 amplitude-binned respiratory states, end-expiration, end-inspiration, six intermediary states during inspiration, and six during expiration using the recorded Navigator signal. XCAT phantoms were then generated based on these MRI data by interactive alignment of the organ contours of the XCAT with the MRI slices using a graphical user interface. Thus far we have created five body motion and five respiratory motion XCAT phantoms from the MRI acquisitions of six healthy volunteers (three males and three females). Non-rigid motion exhibited by the volunteers was reflected in both respiratory and body motion phantoms with a varying extent and character for each individual. In addition to these phantoms, we recorded the position of markers placed on the chest of the volunteers for the body motion studies, which could be used as external motion measurement. Using these phantoms and external motion data, investigators will be able to test their motion correction approaches for realistic motion obtained from different individuals. The non-uniform rational B-spline data and the parameter files for these phantoms are freely available for downloading and can be used with the XCAT license.

Reparative resynchronization in ischemic heart failure: an emerging strategy.

PubMed

Yamada, Satsuki; Terzic, Andre

2014-08-01

Cardiac dyssynchrony refers to disparity in cardiac wall motion, a serious consequence of myocardial infarction associated with poor outcome. Infarct-induced scar is refractory to device-based cardiac resynchronization therapy, which relies on viable tissue. Leveraging the prospect of structural and functional regeneration, reparative resynchronization has emerged as a potentially achievable strategy. In proof-of-concept studies, stem-cell therapy eliminates contractile deficit originating from infarcted regions and secures long-term synchronization with tissue repair. Limited clinical experience suggests benefit of cell interventions in acute and chronic ischemic heart disease as adjuvant to standard of care. A regenerative resynchronization option for dyssynchronous heart failure thus merits validation.

Interventional endocardial motion estimation from electroanatomical mapping data: application to scar characterization.

PubMed

Porras, Antonio R; Piella, Gemma; Berruezo, Antonio; Hoogendoorn, Corne; Andreu, David; Fernandez-Armenta, Juan; Sitges, Marta; Frangi, Alejandro F

2013-05-01

Scar presence and its characteristics play a fundamental role in several cardiac pathologies. To accurately define the extent and location of the scar is essential for a successful ventricular tachycardia ablation procedure. Nowadays, a set of widely accepted electrical voltage thresholds applied to local electrograms recorded are used intraoperatively to locate the scar. Information about cardiac mechanics could be considered to characterize tissues with different viability properties. We propose a novel method to estimate endocardial motion from data obtained with an electroanatomical mapping system together with the endocardial geometry segmented from preoperative 3-D magnetic resonance images, using a statistical atlas constructed with bilinear models. The method was validated using synthetic data generated from ultrasound images of nine volunteers and was then applied to seven ventricular tachycardia patients. Maximum bipolar voltages, commonly used to intraoperatively locate scar tissue, were compared to endocardial wall displacement and strain for all the patients. The results show that the proposed method allows endocardial motion and strain estimation and that areas with low-voltage electrograms also present low strain values.

Comparison of water-based foam and carbon dioxide gas emergency depopulation methods of turkeys.

PubMed

Rankin, M K; Alphin, R L; Benson, E R; Johnson, A L; Hougentogler, D P; Mohankumar, P

2013-12-01

Recommended response strategies for outbreaks of avian influenza and other highly contagious poultry diseases include surveillance, quarantine, depopulation, disposal, and decontamination. The best methods of emergency mass depopulation should maximize human health and safety while minimizing disease spread and animal welfare concerns. The goal of this project was to evaluate the effectiveness of 2 mass depopulation methods on adult tom turkeys. The methods tested were carbon dioxide gassing and water-based foam. The time to unconsciousness, motion cessation, brain death, and altered terminal cardiac activity were recorded for each bird through the use of an electroencephalogram, accelerometer, and electrocardiogram. Critical times for physiological events were extracted from sensor data and compiled in a spreadsheet for statistical analysis. A statistically significant difference was observed in time to brain death, with water-based foam resulting in faster brain death (µ = 190 s) than CO2 gas (µ = 242 s). Though not statistically significant, differences were found comparing the time to unconsciousness (foam: µ = 64 s; CO2 gas: µ = 90 s), motion cessation (foam: µ = 182 s; CO2 gas: µ = 153 s), and altered terminal cardiac activity (foam: µ = 208 s; CO2 gas µ = 242 s) between foam and CO2 depopulation treatments. The results of this study demonstrate that water-based foam can be used to effectively depopulate market size male turkeys.

Tissue Motion and Assembly During Early Cardiovascular Morphogenesis

NASA Astrophysics Data System (ADS)

Rongish, Brenda

2010-03-01

Conventional dogma in the field of cardiovascular developmental biology suggests that cardiac precursor cells migrate to the embryonic midline to form a tubular heart. These progenitors are believed to move relative to their extracellular matrix (ECM); responding to stimulatory and inhibitory cues in their environment. The tubular heart that is formed by 30 hours post fertilization is comprised of two concentric layers: the muscular myocardium and the endothelial-like endocardium, which are separated by a thick layer of ECM believed to be secreted predominantly by the myocardial cells. Here we describe the origin and motility of fluorescently tagged endocardial precursors in transgenic (Tie1-YFP) quail embryos (R. Lansford, Caltech) using epifluorescence time-lapse imaging. To visualize the environment of migrating endocardial progenitors, we labeled two ECM components, fibronectin and fibrillin-2, via in vivo microinjection of fluorochrome-conjugated monoclonal antibodies. Dynamic imaging was performed at stages encompassing tubular heart assembly and early looping. We established the motion of endocardial precursor cells and presumptive cardiac ECM fibrils using both object tracking and particle image velocimetry (image cross correlation). We determined the relative importance of directed cell autonomous motility versus passive tissue movements in endocardial morphogenesis. The data show presumptive endocardial cells and cardiac ECM fibrils are swept passively into the anterior and posterior poles of the elongating tubular heart. These quantitative data indicate the contribution of cell autonomous motility displayed by endocardial precursors is limited. Thus, tissue motion drives most of the cell displacements during endocardial morphogenesis.

A method to improve the B0 homogeneity of the heart in vivo.

PubMed

Jaffer, F A; Wen, H; Balaban, R S; Wolff, S D

1996-09-01

A homogeneous static (B0) magnetic field is required for many NMR experiments such as echo planar imaging, localized spectroscopy, and spiral scan imaging. Although semi-automated techniques have been described to improve the B0 field homogeneity, none has been applied to the in vivo heart. The acquisition of cardiac field maps is complicated by motion, blood flow, and chemical shift artifact from epicardial fat. To overcome these problems, an ungated three-dimensional (3D) chemical shift image (CSI) was collected to generate a time and motion-averaged B0 field map. B0 heterogeneity in the heart was minimized by using a previous algorithm that solves for the optimal shim coil currents for an input field map, using up to third-order current-bounded shims (1). The method improved the B0 homogenelty of the heart in all 11 normal volunteers studied. After application of the algorithm to the unshimmed cardiac field maps, the standard deviation of proton frequency decreased by 43%, the magnitude 1H spectral linewidth decreased by 24%, and the peak-peak gradient decreased by 35%. Simulations of the high-order (second- and third-order) shims in B0 field correction of the heart show that high order shims are important, resulting for nearly half of the improvement in homogeneity for several subjects. The T2* of the left ventricular anterior wall before and after field correction was determined at 4.0 Tesis. Finally, results show that cardiac shimming is of benefit in cardiac 31P NMR spectroscopy and cardiac echo planar imaging.

ECG-based 4D-dose reconstruction of cardiac arrhythmia ablation with carbon ion beams: application in a porcine model

NASA Astrophysics Data System (ADS)

Richter, Daniel; Immo Lehmann, H.; Eichhorn, Anna; Constantinescu, Anna M.; Kaderka, Robert; Prall, Matthias; Lugenbiel, Patrick; Takami, Mitsuru; Thomas, Dierk; Bert, Christoph; Durante, Marco; Packer, Douglas L.; Graeff, Christian

2017-09-01

Noninvasive ablation of cardiac arrhythmia by scanned particle radiotherapy is highly promising, but especially challenging due to cardiac and respiratory motion. Irradiations for catheter-free ablation in intact pigs were carried out at the GSI Helmholtz Center in Darmstadt using scanned carbon ions. Here, we present real-time electrocardiogram (ECG) data to estimate time-resolved (4D) delivered dose. For 11 animals, surface ECGs and temporal structure of beam delivery were acquired during irradiation. R waves were automatically detected from surface ECGs. Pre-treatment ECG-triggered 4D-CT phases were synchronized to the R-R interval. 4D-dose calculation was performed using GSI’s in-house 4D treatment planning system. Resulting dose distributions were assessed with respect to coverage (D95 and V95), heterogeneity (HI  =  D5-D95) and normal tissue exposure. Final results shown here were performed offline, but first calculations were started shortly after irradiation The D95 for TV and PTV was above 95% for 10 and 8 out of 11 animals, respectively. HI was reduced for PTV versus TV volumes, especially for some of the animals targeted at the atrioventricular junction, indicating residual interplay effects due to cardiac motion. Risk structure exposure was comparable to static and 4D treatment planning simulations. ECG-based 4D-dose reconstruction is technically feasible in a patient treatment-like setting. Further development of the presented approach, such as real-time dose calculation, may contribute to safe, successful treatments using scanned ion beams for cardiac arrhythmia ablation.

Estimation of two-dimensional motion velocity using ultrasonic signals beamformed in Cartesian coordinate for measurement of cardiac dynamics

NASA Astrophysics Data System (ADS)

Kaburaki, Kaori; Mozumi, Michiya; Hasegawa, Hideyuki

2018-07-01

Methods for the estimation of two-dimensional (2D) velocity and displacement of physiological tissues are necessary for quantitative diagnosis. In echocardiography with a phased array probe, the accuracy in the estimation of the lateral motion is lower than that of the axial motion. To improve the accuracy in the estimation of the lateral motion, in the present study, the coordinate system for ultrasonic beamforming was changed from the conventional polar coordinate to the Cartesian coordinate. In a basic experiment, the motion velocity of a phantom, which was moved at a constant speed, was estimated by the conventional and proposed methods. The proposed method reduced the bias error and standard deviation in the estimated motion velocities. In an in vivo measurement, intracardiac blood flow was analyzed by the proposed method.

Dynamic CT perfusion imaging of the myocardium: a technical note on improvement of image quality.

PubMed

Muenzel, Daniela; Kabus, Sven; Gramer, Bettina; Leber, Vivian; Vembar, Mani; Schmitt, Holger; Wildgruber, Moritz; Fingerle, Alexander A; Rummeny, Ernst J; Huber, Armin; Noël, Peter B

2013-01-01

To improve image and diagnostic quality in dynamic CT myocardial perfusion imaging (MPI) by using motion compensation and a spatio-temporal filter. Dynamic CT MPI was performed using a 256-slice multidetector computed tomography scanner (MDCT). Data from two different patients-with and without myocardial perfusion defects-were evaluated to illustrate potential improvements for MPI (institutional review board approved). Three datasets for each patient were generated: (i) original data (ii) motion compensated data and (iii) motion compensated data with spatio-temporal filtering performed. In addition to the visual assessment of the tomographic slices, noise and contrast-to-noise-ratio (CNR) were measured for all data. Perfusion analysis was performed using time-density curves with regions-of-interest (ROI) placed in normal and hypoperfused myocardium. Precision in definition of normal and hypoperfused areas was determined in corresponding coloured perfusion maps. The use of motion compensation followed by spatio-temporal filtering resulted in better alignment of the cardiac volumes over time leading to a more consistent perfusion quantification and improved detection of the extend of perfusion defects. Additionally image noise was reduced by 78.5%, with CNR improvements by a factor of 4.7. The average effective radiation dose estimate was 7.1±1.1 mSv. The use of motion compensation and spatio-temporal smoothing will result in improved quantification of dynamic CT MPI using a latest generation CT scanner.

Rationale and methodology of a collaborative learning project in congenital cardiac care

PubMed Central

Wolf, Michael J.; Lee, Eva K.; Nicolson, Susan C.; Pearson, Gail D.; Witte, Madolin K.; Huckaby, Jeryl; Gaies, Michael; Shekerdemian, Lara S.; Mahle, William T.

2018-01-01

Background Collaborative learning is a technique through which individuals or teams learn together by capitalizing on one another’s knowledge, skills, resources, experience, and ideas. Clinicians providing congenital cardiac care may benefit from collaborative learning given the complexity of the patient population and team approach to patient care. Rationale and development Industrial system engineers first performed broad-based time-motion and process analyses of congenital cardiac care programs at 5 Pediatric Heart Network core centers. Rotating multidisciplinary team site visits to each center were completed to facilitate deep learning and information exchange. Through monthly conference calls and an in-person meeting, we determined that duration of mechanical ventilation following infant cardiac surgery was one key variation that could impact a number of clinical outcomes. This was underscored by one participating center’s practice of early extubation in the majority of its patients. A consensus clinical practice guideline using collaborative learning was developed and implemented by multidisciplinary teams from the same 5 centers. The 1-year prospective initiative was completed in May 2015, and data analysis is under way. Conclusion Collaborative learning that uses multidisciplinary team site visits and information sharing allows for rapid structured fact-finding and dissemination of expertise among institutions. System modeling and machine learning approaches objectively identify and prioritize focused areas for guideline development. The collaborative learning framework can potentially be applied to other components of congenital cardiac care and provide a complement to randomized clinical trials as a method to rapidly inform and improve the care of children with congenital heart disease. PMID:26995379

Rationale and methodology of a collaborative learning project in congenital cardiac care.

PubMed

Wolf, Michael J; Lee, Eva K; Nicolson, Susan C; Pearson, Gail D; Witte, Madolin K; Huckaby, Jeryl; Gaies, Michael; Shekerdemian, Lara S; Mahle, William T

2016-04-01

Collaborative learning is a technique through which individuals or teams learn together by capitalizing on one another's knowledge, skills, resources, experience, and ideas. Clinicians providing congenital cardiac care may benefit from collaborative learning given the complexity of the patient population and team approach to patient care. Industrial system engineers first performed broad-based time-motion and process analyses of congenital cardiac care programs at 5 Pediatric Heart Network core centers. Rotating multidisciplinary team site visits to each center were completed to facilitate deep learning and information exchange. Through monthly conference calls and an in-person meeting, we determined that duration of mechanical ventilation following infant cardiac surgery was one key variation that could impact a number of clinical outcomes. This was underscored by one participating center's practice of early extubation in the majority of its patients. A consensus clinical practice guideline using collaborative learning was developed and implemented by multidisciplinary teams from the same 5 centers. The 1-year prospective initiative was completed in May 2015, and data analysis is under way. Collaborative learning that uses multidisciplinary team site visits and information sharing allows for rapid structured fact-finding and dissemination of expertise among institutions. System modeling and machine learning approaches objectively identify and prioritize focused areas for guideline development. The collaborative learning framework can potentially be applied to other components of congenital cardiac care and provide a complement to randomized clinical trials as a method to rapidly inform and improve the care of children with congenital heart disease. Copyright © 2016 Elsevier Inc. All rights reserved.

Population of anatomically variable 4D XCAT adult phantoms for imaging research and optimization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Segars, W. P.; Bond, Jason; Frush, Jack

2013-04-15

Purpose: The authors previously developed the 4D extended cardiac-torso (XCAT) phantom for multimodality imaging research. The XCAT consisted of highly detailed whole-body models for the standard male and female adult, including the cardiac and respiratory motions. In this work, the authors extend the XCAT beyond these reference anatomies by developing a series of anatomically variable 4D XCAT adult phantoms for imaging research, the first library of 4D computational phantoms. Methods: The initial anatomy of each phantom was based on chest-abdomen-pelvis computed tomography data from normal patients obtained from the Duke University database. The major organs and structures for each phantommore » were segmented from the corresponding data and defined using nonuniform rational B-spline surfaces. To complete the body, the authors manually added on the head, arms, and legs using the original XCAT adult male and female anatomies. The structures were scaled to best match the age and anatomy of the patient. A multichannel large deformation diffeomorphic metric mapping algorithm was then used to calculate the transform from the template XCAT phantom (male or female) to the target patient model. The transform was applied to the template XCAT to fill in any unsegmented structures within the target phantom and to implement the 4D cardiac and respiratory models in the new anatomy. Each new phantom was refined by checking for anatomical accuracy via inspection of the models. Results: Using these methods, the authors created a series of computerized phantoms with thousands of anatomical structures and modeling cardiac and respiratory motions. The database consists of 58 (35 male and 23 female) anatomically variable phantoms in total. Like the original XCAT, these phantoms can be combined with existing simulation packages to simulate realistic imaging data. Each new phantom contains parameterized models for the anatomy and the cardiac and respiratory motions and can, therefore, serve as a jumping point from which to create an unlimited number of 3D and 4D variations for imaging research. Conclusions: A population of phantoms that includes a range of anatomical variations representative of the public at large is needed to more closely mimic a clinical study or trial. The series of anatomically variable phantoms developed in this work provide a valuable resource for investigating 3D and 4D imaging devices and the effects of anatomy and motion in imaging. Combined with Monte Carlo simulation programs, the phantoms also provide a valuable tool to investigate patient-specific dose and image quality, and optimization for adults undergoing imaging procedures.« less

Internal Motion Estimation by Internal-external Motion Modeling for Lung Cancer Radiotherapy.

PubMed

Chen, Haibin; Zhong, Zichun; Yang, Yiwei; Chen, Jiawei; Zhou, Linghong; Zhen, Xin; Gu, Xuejun

2018-02-27

The aim of this study is to develop an internal-external correlation model for internal motion estimation for lung cancer radiotherapy. Deformation vector fields that characterize the internal-external motion are obtained by respectively registering the internal organ meshes and external surface meshes from the 4DCT images via a recently developed local topology preserved non-rigid point matching algorithm. A composite matrix is constructed by combing the estimated internal phasic DVFs with external phasic and directional DVFs. Principle component analysis is then applied to the composite matrix to extract principal motion characteristics, and generate model parameters to correlate the internal-external motion. The proposed model is evaluated on a 4D NURBS-based cardiac-torso (NCAT) synthetic phantom and 4DCT images from five lung cancer patients. For tumor tracking, the center of mass errors of the tracked tumor are 0.8(±0.5)mm/0.8(±0.4)mm for synthetic data, and 1.3(±1.0)mm/1.2(±1.2)mm for patient data in the intra-fraction/inter-fraction tracking, respectively. For lung tracking, the percent errors of the tracked contours are 0.06(±0.02)/0.07(±0.03) for synthetic data, and 0.06(±0.02)/0.06(±0.02) for patient data in the intra-fraction/inter-fraction tracking, respectively. The extensive validations have demonstrated the effectiveness and reliability of the proposed model in motion tracking for both the tumor and the lung in lung cancer radiotherapy.

Motion compensation using origin ensembles in awake small animal positron emission tomography

NASA Astrophysics Data System (ADS)

Gillam, John E.; Angelis, Georgios I.; Kyme, Andre Z.; Meikle, Steven R.

2017-02-01

In emission tomographic imaging, the stochastic origin ensembles algorithm provides unique information regarding the detected counts given the measured data. Precision in both voxel and region-wise parameters may be determined for a single data set based on the posterior distribution of the count density allowing uncertainty estimates to be allocated to quantitative measures. Uncertainty estimates are of particular importance in awake animal neurological and behavioral studies for which head motion, unique for each acquired data set, perturbs the measured data. Motion compensation can be conducted when rigid head pose is measured during the scan. However, errors in pose measurements used for compensation can degrade the data and hence quantitative outcomes. In this investigation motion compensation and detector resolution models were incorporated into the basic origin ensembles algorithm and an efficient approach to computation was developed. The approach was validated against maximum liklihood—expectation maximisation and tested using simulated data. The resultant algorithm was then used to analyse quantitative uncertainty in regional activity estimates arising from changes in pose measurement precision. Finally, the posterior covariance acquired from a single data set was used to describe correlations between regions of interest providing information about pose measurement precision that may be useful in system analysis and design. The investigation demonstrates the use of origin ensembles as a powerful framework for evaluating statistical uncertainty of voxel and regional estimates. While in this investigation rigid motion was considered in the context of awake animal PET, the extension to arbitrary motion may provide clinical utility where respiratory or cardiac motion perturb the measured data.

An integrated platform for image-guided cardiac resynchronization therapy

NASA Astrophysics Data System (ADS)

Ma, Ying Liang; Shetty, Anoop K.; Duckett, Simon; Etyngier, Patrick; Gijsbers, Geert; Bullens, Roland; Schaeffter, Tobias; Razavi, Reza; Rinaldi, Christopher A.; Rhode, Kawal S.

2012-05-01

Cardiac resynchronization therapy (CRT) is an effective procedure for patients with heart failure but 30% of patients do not respond. This may be due to sub-optimal placement of the left ventricular (LV) lead. It is hypothesized that the use of cardiac anatomy, myocardial scar distribution and dyssynchrony information, derived from cardiac magnetic resonance imaging (MRI), may improve outcome by guiding the physician for optimal LV lead positioning. Whole heart MR data can be processed to yield detailed anatomical models including the coronary veins. Cine MR data can be used to measure the motion of the LV to determine which regions are late-activating. Finally, delayed Gadolinium enhancement imaging can be used to detect regions of scarring. This paper presents a complete platform for the guidance of CRT using pre-procedural MR data combined with live x-ray fluoroscopy. The platform was used for 21 patients undergoing CRT in a standard catheterization laboratory. The patients underwent cardiac MRI prior to their procedure. For each patient, a MRI-derived cardiac model, showing the LV lead targets, was registered to x-ray fluoroscopy using multiple views of a catheter looped in the right atrium. Registration was maintained throughout the procedure by a combination of C-arm/x-ray table tracking and respiratory motion compensation. Validation of the registration between the three-dimensional (3D) roadmap and the 2D x-ray images was performed using balloon occlusion coronary venograms. A 2D registration error of 1.2 ± 0.7 mm was achieved. In addition, a novel navigation technique was developed, called Cardiac Unfold, where an entire cardiac chamber is unfolded from 3D to 2D along with all relevant anatomical and functional information and coupled to real-time device detection. This allowed more intuitive navigation as the entire 3D scene was displayed simultaneously on a 2D plot. The accuracy of the unfold navigation was assessed off-line using 13 patient data sets by computing the registration error of the LV pacing lead electrodes which was found to be 2.2 ± 0.9 mm. Furthermore, the use of Unfold Navigation was demonstrated in real-time for four clinical cases.

Chasing the reflected wave back into the heart: a new hypothesis while the jury is still out

PubMed Central

Codreanu, Ion; Robson, Matthew D; Rider, Oliver J; Pegg, Tammy J; Jung, Bernd A; Dasanu, Constantin A; Clarke, Kieran; Holloway, Cameron J

2011-01-01

Background: Arterial stiffness directly influences cardiac function and is independently associated with cardiovascular risk. However, the influence of the aortic reflected pulse pressure wave on left ventricular function has not been well characterized. The aim of this study was to obtain detailed information on regional ventricular wall motion patterns corresponding to the propagation of the reflected aortic wave on ventricular segments. Methods: Left ventricular wall motion was investigated in a group of healthy volunteers (n = 14, age 23 ± 3 years), using cardiac magnetic resonance navigator-gated tissue phase mapping. The left ventricle was divided into 16 segments and regional wall motion was studied in high temporal detail. Results: Corresponding to the expected timing of the reflected aortic wave reaching the left ventricle, a characteristic “notch” of regional myocardial motion was seen in all radial, circumferential, and longitudinal velocity graphs. This notch was particularly prominent in septal segments adjacent to the left ventricular outflow tract on radial velocity graphs and in anterior and posterior left ventricular segments on circumferential velocity graphs. Similarly, longitudinal velocity graphs demonstrated a brief deceleration in the upward recoil motion of the entire ventricle at the beginning of diastole. Conclusion: These results provide new insights into the possible influence of the reflected aortic waves on ventricular segments. Although the association with the reflected wave appears to us to be unambiguous, it represents a novel research concept, and further studies enabling the actual recording of the pulse wave are required. PMID:21731888

Patient-Specific Simulation of Cardiac Blood Flow From High-Resolution Computed Tomography.

PubMed

Lantz, Jonas; Henriksson, Lilian; Persson, Anders; Karlsson, Matts; Ebbers, Tino

2016-12-01

Cardiac hemodynamics can be computed from medical imaging data, and results could potentially aid in cardiac diagnosis and treatment optimization. However, simulations are often based on simplified geometries, ignoring features such as papillary muscles and trabeculae due to their complex shape, limitations in image acquisitions, and challenges in computational modeling. This severely hampers the use of computational fluid dynamics in clinical practice. The overall aim of this study was to develop a novel numerical framework that incorporated these geometrical features. The model included the left atrium, ventricle, ascending aorta, and heart valves. The framework used image registration to obtain patient-specific wall motion, automatic remeshing to handle topological changes due to the complex trabeculae motion, and a fast interpolation routine to obtain intermediate meshes during the simulations. Velocity fields and residence time were evaluated, and they indicated that papillary muscles and trabeculae strongly interacted with the blood, which could not be observed in a simplified model. The framework resulted in a model with outstanding geometrical detail, demonstrating the feasibility as well as the importance of a framework that is capable of simulating blood flow in physiologically realistic hearts.

Mechanical Dyssynchrony Precedes QRS Widening in ATP‐Sensitive K+ Channel–Deficient Dilated Cardiomyopathy

PubMed Central

Yamada, Satsuki; Arrell, D. Kent; Kane, Garvan C.; Nelson, Timothy J.; Perez‐Terzic, Carmen M.; Behfar, Atta; Purushothaman, Saranya; Prinzen, Frits W.; Auricchio, Angelo; Terzic, Andre

2013-01-01

Background Contractile discordance exacerbates cardiac dysfunction, aggravating heart failure outcome. Dissecting the genesis of mechanical dyssynchrony would enable an early diagnosis before advanced disease. Methods and Results High‐resolution speckle‐tracking echocardiography was applied in a knockout murine surrogate of adult‐onset human cardiomyopathy caused by mutations in cardioprotective ATP‐sensitive K+ (KATP) channels. Preceding the established criteria of cardiac dyssynchrony, multiparametric speckle‐based strain resolved nascent erosion of dysfunctional regions within cardiomyopathic ventricles of the KATP channel–null mutant exposed to hemodynamic stress. Not observed in wild‐type counterparts, intraventricular disparity in wall motion, validated by the degree, direction, and delay of myocardial speckle patterns, unmasked the disease substrate from asymptomatic to overt heart failure. Mechanical dyssynchrony preceded widening of the QRS complex and exercise intolerance and progressed into global myocardial discoordination and decompensated cardiac pump function, precipitating a low output syndrome. Conclusions The present study, with the use of high‐resolution imaging, prospectively resolved the origin and extent of intraventricular motion disparity in a KATP channel–knockout model of dilated cardiomyopathy. Mechanical dyssynchrony established as an early marker of cardiomyopathic disease offers novel insight into the pathodynamics of dyssynchronous heart failure. PMID:24308936

Computational Modeling of Open-Irrigated Electrodes for Radiofrequency Cardiac Ablation Including Blood Motion-Saline Flow Interaction

PubMed Central

González-Suárez, Ana; Berjano, Enrique; Guerra, Jose M.; Gerardo-Giorda, Luca

2016-01-01

Radiofrequency catheter ablation (RFCA) is a routine treatment for cardiac arrhythmias. During RFCA, the electrode-tissue interface temperature should be kept below 80°C to avoid thrombus formation. Open-irrigated electrodes facilitate power delivery while keeping low temperatures around the catheter. No computational model of an open-irrigated electrode in endocardial RFCA accounting for both the saline irrigation flow and the blood motion in the cardiac chamber has been proposed yet. We present the first computational model including both effects at once. The model has been validated against existing experimental results. Computational results showed that the surface lesion width and blood temperature are affected by both the electrode design and the irrigation flow rate. Smaller surface lesion widths and blood temperatures are obtained with higher irrigation flow rate, while the lesion depth is not affected by changing the irrigation flow rate. Larger lesions are obtained with increasing power and the electrode-tissue contact. Also, larger lesions are obtained when electrode is placed horizontally. Overall, the computational findings are in close agreement with previous experimental results providing an excellent tool for future catheter research. PMID:26938638

Application of the 4-D XCAT Phantoms in Biomedical Imaging and Beyond.

PubMed

Segars, W Paul; Tsui, B M W; Cai, Jing; Yin, Fang-Fang; Fung, George S K; Samei, Ehsan

2018-03-01

The four-dimensional (4-D) eXtended CArdiac-Torso (XCAT) series of phantoms was developed to provide accurate computerized models of the human anatomy and physiology. The XCAT series encompasses a vast population of phantoms of varying ages from newborn to adult, each including parameterized models for the cardiac and respiratory motions. With great flexibility in the XCAT's design, any number of body sizes, different anatomies, cardiac or respiratory motions or patterns, patient positions and orientations, and spatial resolutions can be simulated. As such, the XCAT phantoms are gaining a wide use in biomedical imaging research. There they can provide a virtual patient base from which to quantitatively evaluate and improve imaging instrumentation, data acquisition, techniques, and image reconstruction and processing methods which can lead to improved image quality and more accurate clinical diagnoses. The phantoms have also found great use in radiation dosimetry, radiation therapy, medical device design, and even the security and defense industry. This review paper highlights some specific areas in which the XCAT phantoms have found use within biomedical imaging and other fields. From these examples, we illustrate the increasingly important role that computerized phantoms and computer simulation are playing in the research community.

Echocardiography: pericardial thickening and constrictive pericarditis.

PubMed

Schnittger, I; Bowden, R E; Abrams, J; Popp, R L

1978-09-01

A total of 167 patients with pericardial thickening noted on M node echocardiography were studied retrospectively. After the echocardiogram, 72 patients underwent cardiac surgery, cardiac catheterization or autopsy for various heart diseases; 96 patients had none of these procedures. In 49 patients the pericardium was directly visualized at surgery or autopsy; 76 percent of these had pericardial thickening or adhesions. In another 8 percent, pericardial adhesions were absent, but no comment had been made about the appearance of the pericardium itself. In the remaining 16 percent, no comment had been made about the pericardium or percardial space. Cardiac catheterization in 64 patients revealed 24 with hemodynamic findings of constrictive pericarditis or effusive constrictive disease. Seven echocardiographic patterns consistent with pericardial adhesions or pericardial thickening are described and related when possible to the subsequent findings at heart surgery or autopsy. The clinical diagnoses of 167 patients with pericardial thickening are presented. The hemodynamic diagnosis of constrictive pericardial disease was associated with the echocardiographic finding of pericardial thickening, but there were no consistent echocardiographic patterns of pericardial thickening diagnostic of constriction. However, certain other echocardiographic abnormalities of left ventricular posterior wall motion and interventricular septal motion and a high E-Fo slope were suggestive of constriction.

Real-time fusion of endoscopic views with dynamic 3-D cardiac images: a phantom study.

PubMed

Szpala, Stanislaw; Wierzbicki, Marcin; Guiraudon, Gerard; Peters, Terry M

2005-09-01

Minimally invasive robotically assisted cardiac surgical systems currently do not routinely employ 3-D image guidance. However, preoperative magnetic resonance and computed tomography (CT) images have the potential to be used in this role, if appropriately registered with the patient anatomy and animated synchronously with the motion of the actual heart. This paper discusses the fusion of optical images of a beating heart phantom obtained from an optically tracked endoscope, with volumetric images of the phantom created from a dynamic CT dataset. High quality preoperative dynamic CT images are created by first extracting the motion parameters of the heart from the series of temporal frames, and then applying this information to animate a high-quality heart image acquired at end systole. Temporal synchronization of the endoscopic and CT model is achieved by selecting the appropriate CT image from the dynamic set, based on an electrocardiographic trigger signal. The spatial error between the optical and virtual images is 1.4 +/- 1.1 mm, while the time discrepancy is typically 50-100 ms. Index Terms-Image guidance, image warping, minimally invasive cardiac surgery, virtual endoscopy, virtual reality.

Mapping cardiac fiber orientations from high-resolution DTI to high-frequency 3D ultrasound

NASA Astrophysics Data System (ADS)

Qin, Xulei; Wang, Silun; Shen, Ming; Zhang, Xiaodong; Wagner, Mary B.; Fei, Baowei

2014-03-01

The orientation of cardiac fibers affects the anatomical, mechanical, and electrophysiological properties of the heart. Although echocardiography is the most common imaging modality in clinical cardiac examination, it can only provide the cardiac geometry or motion information without cardiac fiber orientations. If the patient's cardiac fiber orientations can be mapped to his/her echocardiography images in clinical examinations, it may provide quantitative measures for diagnosis, personalized modeling, and image-guided cardiac therapies. Therefore, this project addresses the feasibility of mapping personalized cardiac fiber orientations to three-dimensional (3D) ultrasound image volumes. First, the geometry of the heart extracted from the MRI is translated to 3D ultrasound by rigid and deformable registration. Deformation fields between both geometries from MRI and ultrasound are obtained after registration. Three different deformable registration methods were utilized for the MRI-ultrasound registration. Finally, the cardiac fiber orientations imaged by DTI are mapped to ultrasound volumes based on the extracted deformation fields. Moreover, this study also demonstrated the ability to simulate electricity activations during the cardiac resynchronization therapy (CRT) process. The proposed method has been validated in two rat hearts and three canine hearts. After MRI/ultrasound image registration, the Dice similarity scores were more than 90% and the corresponding target errors were less than 0.25 mm. This proposed approach can provide cardiac fiber orientations to ultrasound images and can have a variety of potential applications in cardiac imaging.

Intravital imaging of cardiac function at the single-cell level.

PubMed

Aguirre, Aaron D; Vinegoni, Claudio; Sebas, Matt; Weissleder, Ralph

2014-08-05

Knowledge of cardiomyocyte biology is limited by the lack of methods to interrogate single-cell physiology in vivo. Here we show that contracting myocytes can indeed be imaged with optical microscopy at high temporal and spatial resolution in the beating murine heart, allowing visualization of individual sarcomeres and measurement of the single cardiomyocyte contractile cycle. Collectively, this has been enabled by efficient tissue stabilization, a prospective real-time cardiac gating approach, an image processing algorithm for motion-artifact-free imaging throughout the cardiac cycle, and a fluorescent membrane staining protocol. Quantification of cardiomyocyte contractile function in vivo opens many possibilities for investigating myocardial disease and therapeutic intervention at the cellular level.

Patient-specific CFD simulation of intraventricular haemodynamics based on 3D ultrasound imaging.

PubMed

Bavo, A M; Pouch, A M; Degroote, J; Vierendeels, J; Gorman, J H; Gorman, R C; Segers, P

2016-09-09

The goal of this paper is to present a computational fluid dynamic (CFD) model with moving boundaries to study the intraventricular flows in a patient-specific framework. Starting from the segmentation of real-time transesophageal echocardiographic images, a CFD model including the complete left ventricle and the moving 3D mitral valve was realized. Their motion, known as a function of time from the segmented ultrasound images, was imposed as a boundary condition in an Arbitrary Lagrangian-Eulerian framework. The model allowed for a realistic description of the displacement of the structures of interest and for an effective analysis of the intraventricular flows throughout the cardiac cycle. The model provides detailed intraventricular flow features, and highlights the importance of the 3D valve apparatus for the vortex dynamics and apical flow. The proposed method could describe the haemodynamics of the left ventricle during the cardiac cycle. The methodology might therefore be of particular importance in patient treatment planning to assess the impact of mitral valve treatment on intraventricular flow dynamics.

Enhancing Long-Term Motivation of Cardiac Patients by Applying Exergaming in Rehabilitation Training.

PubMed

Volmer, Joe; Burkert, Malte; Krumm, Heiko; Abodahab, Abdurrahman; Dinklage, Patrick; Feltmann, Marius; Kröger, Chris; Panta, Pernes; Schäfer, Felix; Scheidt, David; Sellung, Marcel; Singerhoff, Hauke; Steingrefer, Christofer; Schmidt, Thomas; Hoffmann, Jan-Dirk; Willemsen, Detlev; Reiss, Nils

2017-01-01

Although regular physical activities reduce mortality and increase quality of life many cardiac patients discontinue training due to lack of motivation, lack of time or having health concerns because of a too high training intensity. Therefore, we developed an exergaming based system to enhance long-term motivation in the context of rehabilitation training. We combined different hardware components such as vital sensors, a virtual reality headset, a motion detecting camera, a bicycle ergometer and a motion platform to create an immersive and fun experience for the training user without having to worry about any negative health impact. Our evaluation shows that the system is well accepted by the users and is capable of tackling the aforementioned reasons for an inactive lifestyle. The system is designed to be easily extensible, safe to use and enables professionals to adjust and to telemonitor the training at any time.

Respiratory motion correction in emission tomography image reconstruction.

PubMed

Reyes, Mauricio; Malandain, Grégoire; Koulibaly, Pierre Malick; González Ballester, Miguel A; Darcourt, Jacques

2005-01-01

In Emission Tomography imaging, respiratory motion causes artifacts in lungs and cardiac reconstructed images, which lead to misinterpretations and imprecise diagnosis. Solutions like respiratory gating, correlated dynamic PET techniques, list-mode data based techniques and others have been tested with improvements over the spatial activity distribution in lungs lesions, but with the disadvantages of requiring additional instrumentation or discarding part of the projection data used for reconstruction. The objective of this study is to incorporate respiratory motion correction directly into the image reconstruction process, without any additional acquisition protocol consideration. To this end, we propose an extension to the Maximum Likelihood Expectation Maximization (MLEM) algorithm that includes a respiratory motion model, which takes into account the displacements and volume deformations produced by the respiratory motion during the data acquisition process. We present results from synthetic simulations incorporating real respiratory motion as well as from phantom and patient data.

Resveratrol Improves Myocardial Perfusion in a Swine Model of Hypercholesterolemia and Chronic Myocardial Ischemia

PubMed Central

Robich, Michael P.; Osipov, Robert M.; Nezafat, Reza; Feng, Jun; Clements, Richard T.; Bianchi, Cesario; Boodhwani, Munir; Coady, Michael A.; Laham, Roger J.; Sellke, Frank W.

2010-01-01

Introduction Resveratrol may provide protection against coronary artery disease. We hypothesized that supplemental resveratrol will improve cardiac perfusion in the ischemic territory of swine with hypercholesterolemia and chronic myocardial ischemia. Methods and Results Yorkshire swine were fed either a normal diet (control, n=7), a hypercholesterolemic diet (HCC, n=7), or a hypercholesterolemic diet with supplemental resveratrol (100 mg/kg/day orally, HCRV, n=7). Four weeks later, an ameroid constrictor was placed on the left circumflex artery. Animals underwent cardiac magnetic resonance imaging and coronary angiography 7 weeks later, prior to sacrifice and tissue harvest. Total cholesterol was lowered about 30% in HCRV animals (p<0.001). Regional wall motion analysis demonstrated a significant decrease in inferolateral function from baseline to 7 weeks in HCC swine (p=0.04). There was no significant change in regional function in HCRV swine from baseline to 7 weeks (p=0.32). Tissue blood flow during stress was 2.8 fold greater in HCRV swine when compared to HCC swine (p=0.04). Endothelial dependent microvascular relaxation response to Substance P was diminished in HCC swine which was rescued by resveratrol treatment (p=0.004). Capillary density (PECAM-1 staining) demonstrated fewer capillaries in both HCC and HCRV swine v. control swine (p=0.02). Immunoblot analysis demonstrated significantly greater expression in HCRV v. HCC swine of the following markers of angiogenesis: VEGF (p=0.002), peNOS(ser1177)(p=0.04), NFkB (p=0.004), and pAkt(thr308)(p=0.001). Conclusion Supplemental resveratrol attenuates regional wall motion abnormalities, improves myocardial perfusion in the collateral dependent region, preserves endothelial dependent coronary vessel function, and upregulates markers of angiogenesis associated with the VEGF signaling pathway. PMID:20837905

Cardiac contraction motion compensation in gated myocardial perfusion SPECT: A comparative study.

PubMed

Salehi, Narges; Rahmim, Arman; Fatemizadeh, Emad; Akbarzadeh, Afshin; Farahani, Mohammad Hossein; Farzanefar, Saeed; Ay, Mohammad Reza

2018-05-01

Cardiac contraction significantly degrades quality and quantitative accuracy of gated myocardial perfusion SPECT (MPS) images. In this study, we aimed to explore different techniques in motion-compensated temporal processing of MPS images and their impact on image quality and quantitative accuracy. 50 patients without known heart condition underwent gated MPS. 3D motion compensation methods using Motion Freezing by Cedars Sinai (MF), Log-domain Diffeomorphic Demons (LDD) and Free-Form Deformation (FFD) were applied to warp all image phases to fit the end-diastolic (ED) phase. Afterwards, myocardial wall thickness, myocardial to blood pool contrast, and image contrast-to noise ratio (CNR) were measured in summed images with no motion compensation (NoMC) and compensated images (MF, LDD and FFD). Total Perfusion Defect (TPD) was derived from Cedars-Sinai software, on the basis of sex-specific normal limits. Left ventricle (LV) lateral wall thickness was reduced after applying motion compensation (p < 0.05). Myocardial to blood pool contrast and CNR in compensated images were greater than NoMC (p < 0.05). TPD_LDD was in good agreement with the corresponding TPD_MF (p = 0.13). All methods have improved image quality and quantitative performance relative to NoMC. LDD and FFD are fully automatic and do not require any manual intervention, while MF is dependent on contour definition. In terms of diagnostic parameters LDD is in good agreement with MF which is a clinically accepted method. Further investigation along with diagnostic reference standards, in order to specify diagnostic value of each technique is recommended. Copyright © 2018 Associazione Italiana di Fisica Medica. All rights reserved.

Cardiac T1 Imaging

PubMed Central

Jerosch-Herold, Michael; Kwong, Raymond Y.

2014-01-01

T1 mapping of the heart has evolved into a valuable tool to evaluate myocardial tissue properties, with or without contrast injection, including assessment of myocardial edema and free water content, extra-cellular volume (expansion), and most recently cardiomyocyte hypertrophy. The MRI pulse sequence techniques developed for these applications have had to address at least two important considerations for cardiac applications: measure magnetization inversion recoveries during cardiac motion with sufficient temporal resolution for the shortest expected T1 values, and, secondly, obtain these measurements within a time during which a patient can comfortably suspend breathing. So-called Look-Locker techniques, and variants thereof, which all sample multiple points of a magnetization recovery after each magnetization preparation have therefore become a mainstay in this field. The rapid pace of advances and new findings based on cardiac T1 mapping for assessment of diffuse fibrosis, or myocardial edema show that these techniques enrich the capabilities of MRI for myocardial tissue profiling, which is arguably unmatched by other cardiac imaging modalities. PMID:24509619

Relationship between heart rate and quiescent interval of the cardiac cycle in children using MRI.

PubMed

Zhang, Wei; Bogale, Saivivek; Golriz, Farahnaz; Krishnamurthy, Rajesh

2017-11-01

Imaging the heart in children comes with the challenge of constant cardiac motion. A prospective electrocardiography-triggered CT scan allows for scanning during a predetermined phase of the cardiac cycle with least motion. This technique requires knowing the optimal quiescent intervals of cardiac cycles in a pediatric population. To evaluate high-temporal-resolution cine MRI of the heart in children to determine the relationship of heart rate to the optimal quiescent interval within the cardiac cycle. We included a total of 225 consecutive patients ages 0-18 years who had high-temporal-resolution cine steady-state free-precession sequence performed as part of a magnetic resonance imaging (MRI) or magnetic resonance angiography study of the heart. We determined the location and duration of the quiescent interval in systole and diastole for heart rates ranging 40-178 beats per minute (bpm). We performed the Wilcoxon signed rank test to compare the duration of quiescent interval in systole and diastole for each heart rate group. The duration of the quiescent interval at heart rates <80 bpm and >90 bpm was significantly longer in diastole and systole, respectively (P<.0001 for all ranges, except for 90-99 bpm [P=.02]). For heart rates 80-89 bpm, diastolic interval was longer than systolic interval, but the difference was not statistically significant (P=.06). We created a chart depicting optimal quiescent intervals across a range of heart rates that could be applied for prospective electrocardiography-triggered CT imaging of the heart. The optimal quiescent interval at heart rates <80 bpm is in diastole and at heart rates ≥90 bpm is in systole. The period of quiescence at heart rates 80-89 bpm is uniformly short in systole and diastole.

An Exploratory Study of Functional Status in Post Cardiac Arrest Survivors Discharged To Home

DTIC Science & Technology

2005-08-01

estimate of the calories burned throughout the day. It measured vertical acceleration (i.e., up and down motion) and total caloric expenditure (i.e...an estimate of caloric expenditure and the intensity of one’s activity; the higher the intensity, the more calories the unit registered. A small...number of daily steps taken. It measures vertical acceleration (i.e., up and down motion) and total caloric expenditure (i.e., the calories one’s

Quantification of motion of the thoracic aorta after ascending aortic repair of type-A dissection.

PubMed

Suh, Ga-Young; Fleischmann, Dominik; Beygui, Ramin E; Cheng, Christopher P

2017-05-01

To quantify cardiac and respiratory deformations of the thoracic aorta after ascending aortic graft repair. Eight patients were scanned with cardiac-resolved computed tomography angiography during inspiratory/expiratory breath-holds. Aortic centerlines and lumen were extracted to compute the arclength, curvature, angulation, and cross-section shape. From systole to diastole, the angle of graft [Formula: see text] arch increased by 2.4[Formula: see text] ± 1.8[Formula: see text] (P < 0.01) and the angle of arch [Formula: see text] descending aorta decreased by 2.4[Formula: see text] ± 2.6[Formula: see text] (P < 0.05), while the effective diameter of the proximal arch decreased by 2.4 ± 1.9% (P < 0.01), a greater change than those of the graft or distal arch (P < 0.05). From inspiration to expiration, the angle of graft [Formula: see text] arch increased by 2.8[Formula: see text] ± 2.6[Formula: see text] (P < 0.02) with the peak curvature increase (P < 0.05). Shorter graft length was correlated with greater cardiac-induced graft [Formula: see text] arch angulation, and longer graft length was correlated with greater respiratory-induced arch [Formula: see text] descending aorta angulation (R [Formula: see text] 0.50). The thoracic aorta changed curvature and angulation with cardiac and respiratory influences, driven by aortic root and arch motion. The thoracic aortic geometry and deformation are correlated with the ascending aortic graft length.

A Fiber-Based Ratiometric Optical Cardiac Mapping Channel Using a Diffraction Grating and Split Detector

PubMed Central

Brown, Ninita H.; Dobrovolny, Hana M.; Gauthier, Daniel J.; Wolf, Patrick D.

2007-01-01

Optical fiber-based mapping systems are used to record the cardiac action potential (AP) throughout the myocardium. The optical AP contains a contraction-induced motion artifact (MA), which makes it difficult to accurately measure the action potential duration (APD). MA is removed by preventing contraction with electrical-mechanical uncoupling drugs, such as 2,3-butanedione monoxime (BDM). We designed a novel fiber-based ratiometric optical channel using a blue light emitting diode, a diffraction grating, and a split photodetector that can accurately measure the cardiac AP without the need for BDM. The channel was designed based on simulations using the optical design software ZEMAX. The channel has an electrical bandwidth of 150 Hz and an root mean-square dark noise of 742 μV. The channel successfully recorded the cardiac AP from the wall of five rabbit heart preparations without the use of BDM. After 20-point median filtering, the mean signal/noise ratio was 25.3 V/V. The APD measured from the base of a rabbit heart was 134 ± 8.4 ms, compared to 137.6 ± 3.3 ms from simultaneous microelectrode recordings. This difference was not statistically significant (p-value = 0.3). The quantity of MA removed was also measured using the motion ratio. The reduction in MA was significant (p-value = 0.0001). This fiber-based system is the first of its kind to enable optical APD measurements in the beating heart wall without the use of BDM. PMID:17416627

Towards robust specularity detection and inpainting in cardiac images

NASA Astrophysics Data System (ADS)

Alsaleh, Samar M.; Aviles, Angelica I.; Sobrevilla, Pilar; Casals, Alicia; Hahn, James

2016-03-01

Computer-assisted cardiac surgeries had major advances throughout the years and are gaining more popularity over conventional cardiac procedures as they offer many benefits to both patients and surgeons. One obvious advantage is that they enable surgeons to perform delicate tasks on the heart while it is still beating, avoiding the risks associated with cardiac arrest. Consequently, the surgical system needs to accurately compensate the physiological motion of the heart which is a very challenging task in medical robotics since there exist different sources of disturbances. One of which is the bright light reflections, known as specular highlights, that appear on the glossy surface of the heart and partially occlude the field of view. This work is focused on developing a robust approach that accurately detects and removes those highlights to reduce their disturbance to the surgeon and the motion compensation algorithm. As a first step, we exploit both color attributes and Fuzzy edge detector to identify specular regions in each acquired image frame. These two techniques together work as restricted thresholding and are able to accurately identify specular regions. Then, in order to eliminate the specularity artifact and give the surgeon a better perception of the heart, the second part of our solution is dedicated to correct the detected regions using inpainting to propagate and smooth the results. Our experimental results, which we carry out in realistic datasets, reveal how efficient and precise the proposed solution is, as well as demonstrate its robustness and real-time performance.

Direct Three-Dimensional Myocardial Strain Tensor Quantification and Tracking using zHARP★

PubMed Central

Abd-Elmoniem, Khaled Z.; Stuber, Matthias; Prince, Jerry L.

2008-01-01

Images of myocardial strain can be used to diagnose heart disease, plan and monitor treatment, and to learn about cardiac structure and function. Three-dimensional (3-D) strain is typically quantified using many magnetic resonance (MR) images obtained in two or three orthogonal planes. Problems with this approach include long scan times, image misregistration, and through-plane motion. This article presents a novel method for calculating cardiac 3-D strain using a stack of two or more images acquired in only one orientation. The zHARP pulse sequence encodes in-plane motion using MR tagging and out-of-plane motion using phase encoding, and has been previously shown to be capable of computing 3D displacement within a single image plane. Here, data from two adjacent image planes are combined to yield a 3-D strain tensor at each pixel; stacks of zHARP images can be used to derive stacked arrays of 3D strain tensors without imaging multiple orientations and without numerical interpolation. The performance and accuracy of the method is demonstrated in-vitro on a phantom and in-vivo in four healthy adult human subjects. PMID:18511332

Characterization of cardiac flow in heart disease patients by computational fluid dynamics and 4D flow MRI

NASA Astrophysics Data System (ADS)

Lantz, Jonas; Gupta, Vikas; Henriksson, Lilian; Karlsson, Matts; Persson, Ander; Carhall, Carljohan; Ebbers, Tino

2017-11-01

In this study, cardiac blood flow was simulated using Computational Fluid Dynamics and compared to in vivo flow measurements by 4D Flow MRI. In total, nine patients with various heart diseases were studied. Geometry and heart wall motion for the simulations were obtained from clinical CT measurements, with 0.3x0.3x0.3 mm spatial resolution and 20 time frames covering one heartbeat. The CFD simulations included pulmonary veins, left atrium and ventricle, mitral and aortic valve, and ascending aorta. Mesh sizes were on the order of 6-16 million cells, depending on the size of the heart, in order to resolve both papillary muscles and trabeculae. The computed flow field agreed visually very well with 4D Flow MRI, with characteristic vortices and flow structures seen in both techniques. Regression analysis showed that peak flow rate as well as stroke volume had an excellent agreement for the two techniques. We demonstrated the feasibility, and more importantly, fidelity of cardiac flow simulations by comparing CFD results to in vivo measurements. Both qualitative and quantitative results agreed well with the 4D Flow MRI measurements. Also, the developed simulation methodology enables ``what if'' scenarios, such as optimization of valve replacement and other surgical procedures. Funded by the Wallenberg Foundation.

Added value of cardiac computed tomography for evaluation of mechanical aortic valve: Emphasis on evaluation of pannus with surgical findings as standard reference.

PubMed

Suh, Young Joo; Lee, Sak; Im, Dong Jin; Chang, Suyon; Hong, Yoo Jin; Lee, Hye-Jeong; Hur, Jin; Choi, Byoung Wook; Chang, Byung-Chul; Shim, Chi Young; Hong, Geu-Ru; Kim, Young Jin

2016-07-01

The added value of cardiac computed tomography (CT) with transesophageal echocardiography (TEE) for evaluating mechanical aortic valve (AV) dysfunction has not yet been investigated. The purposes of this study were to investigate the added value of cardiac CT for evaluation of mechanical AVs and diagnoses of pannus compared to TEE, with surgical findings of redo-aortic valve replacement (AVR) used as a standard reference. 25 patients who underwent redo-AVR due to mechanical AV dysfunction and cardiac CT before redo-AVR were included. The presence of pannus, encroachment ratio by pannus, and limitation of motion (LOM) were evaluated on CT. The diagnostic performance of pannus detection was compared using TEE, CT, and CT+TEE, with surgical findings as a standard reference. The added value of CT for diagnosing the cause of mechanical AV dysfunction was assessed compared to TTE+TEE. In two patients, CT analysis was not feasible due to severe metallic artifacts. On CT, pannus and LOM were found in 100% (23/23) and 60.9% (14/23). TEE identified pannus in 48.0% of patients (12/25). CT, TEE, and CT+TEE correctly identified pannus with sensitivity of 92.0%, 48.0%, and 92.0%, respectively (P=0.002 for CT vs. TEE). In 11 of 13 cases (84.6%) with inconclusive or negative TEE results for pannus, CT detected the pannus. Among 13 inconclusive cases of TTE+TEE for the cause of mechanical AV dysfunction, CT suggested 6 prosthetic valve obstruction (PVO) by pannus, 4 low-flow low-gradient PVO, and one LOM without significant PVO. Cardiac CT showed added diagnostic value with TEE in the detection of pannus as the cause of mechanical AV dysfunction. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Association of Central Adiposity With Adverse Cardiac Mechanics: Findings From the Hypertension Genetic Epidemiology Network Study.

PubMed

Selvaraj, Senthil; Martinez, Eva E; Aguilar, Frank G; Kim, Kwang-Youn A; Peng, Jie; Sha, Jin; Irvin, Marguerite R; Lewis, Cora E; Hunt, Steven C; Arnett, Donna K; Shah, Sanjiv J

2016-06-01

Central obesity, defined by increased waist circumference or waist:hip ratio (WHR), is associated with increased cardiovascular events, including heart failure. However, the pathophysiological link between central obesity and adverse cardiovascular outcomes remains poorly understood. We hypothesized that central obesity and larger WHR are independently associated with worse cardiac mechanics (reduced left ventricular strain and systolic [s'] and early diastolic [e'] tissue velocities). We performed speckle-tracking analysis of echocardiograms from participants in the Hypertension Genetic Epidemiology Network (HyperGEN) study, a population- and family-based epidemiological study (n=2181). Multiple indices of systolic and diastolic cardiac mechanics were measured. We evaluated the association between central obesity and cardiac mechanics using multivariable-adjusted linear mixed-effects models to account for relatedness among participants. The mean age of the cohort was 51±14 years, 58% were women, and 47% were black. Mean body mass index was 30.8±7.1 kg/m(2), waist circumference was 102±17 cm, WHR was 0.91±0.08, and 80% had central obesity based on waist circumference and WHR criteria. After adjusting for multiple potential confounders (including age, sex, race, physical activity, body mass index, heart rate, smoking status, systolic blood pressure, fasting glucose, total cholesterol, antihypertensive medication use, glomerular filtration rate, left ventricular mass index, wall motion abnormalities, and ejection fraction), central obesity and WHR remained associated with worse global longitudinal strain, early diastolic strain rate, s' velocity, and e' velocity (P<0.05 for all comparisons). There were no significant statistical interactions between WHR and obesity status. In this cross-sectional study of participants with multiple comorbidities, central obesity was found to be associated with adverse cardiac mechanics. © 2016 American Heart Association, Inc.

Fetal motion estimation from noninvasive cardiac signal recordings.

PubMed

Biglari, Hadis; Sameni, Reza

2016-11-01

Fetal motility is a widely accepted indicator of the well-being of a fetus. In previous research, it has be shown that fetal motion (FM) is coherent with fetal heart rate accelerations and an indicator for active/rest cycles of the fetus. The most common approach for FM and fetal heart rate (FHR) assessment is by Doppler ultrasound (DUS). While DUS is the most common approach for studying the mechanical activities of the heart, noninvasive fetal electrocardiogram (ECG) and magnetocardiogram (MCG) recording and processing techniques have been considered as a possible competitor (or complement) for the DUS. In this study, a fully automatic and robust framework is proposed for the extraction, ranking and alignment of fetal QRS-complexes from noninvasive fetal ECG/MCG. Using notions from subspace tracking, two measures, namely the actogram and rotatogram, are defined for fetal motion tracking. The method is applied to four fetal ECG/MCG databases, including twin MCG recordings. By defining a novel measure of causality, it is shown that there is significant coherency and causal relationship between the actogram/rotatogram and FHR accelerations/decelerations. Using this measure, it is shown that in many cases, the actogram and rotatogram precede the FHR variations, which supports the idea of motion-induced FHR accelerations/decelerations for these cases and raises attention for the non-motion-induced FHR variations, which can be associated to the fetal central nervous system developments. The results of this study can lead to novel perspectives of the fetal sympathetic and parasympathetic brain systems and future requirements of fetal cardiac monitoring.

Left ventricle changes early after breath-holding in deep water in elite apnea divers.

PubMed

Pingitore, Alessandro; Gemignani, Angelo; Menicucci, Danilo; Passera, Mirko; Frassi, Francesca; Marabotti, Claudio; Piarulli, Andrea; Benassi, Antonio; L'Abbate, Antonio; Bedini, Remo

2010-01-01

To study by ultrasounds cardiac morphology and function early after breath-hold diving in deep water in elite athletes. Fifteen healthy male divers (age 28 +/- 3 years) were studied using Doppler-echocardiography, immediately before (basal condition, BC) and two minutes after breath-hold diving (40 meters, acute post-apnea condition, APAC). Each subject performed a series of three consecutive breath-hold dives (20-30 and 40 m depth). End-diastolic left ventricular (LV) diameter (EDD) and end-diastolic LV volume (EDV) increased significantly (p < 0.01). Stroke volume (SV), cardiac index (CI), septal and posterior systolic wall-thickening (SWT) also significantly increased after diving (p < 0.01). No wall motion abnormalities were detected, and wall motion score index was unchanged between BC and APAC. Doppler mitral E wave increased significantly (p < 0.01), whereas the A wave was unchanged. Systemic vascular resistance (SVR) decreased significantly after diving (p < 0.05). In the factor analysis, filtering out the absolute values smaller than 0.7 in the loading matrix, it resulted that factor I consists of EDV, posterior SWT, SV and CI, factor II of diastolic blood pressure, waves A and E and factor III of heart rate and SVR. Systo-diastolic functions were improved in the early period after deep breath-hold diving due to favorable changes in loading conditions relative to pre-diving, namely the recruitment of left ventricular preload reserve and the reduction in afterload.

Motion correction for improved estimation of heart rate using a visual spectrum camera

NASA Astrophysics Data System (ADS)

Tarbox, Elizabeth A.; Rios, Christian; Kaur, Balvinder; Meyer, Shaun; Hirt, Lauren; Tran, Vy; Scott, Kaitlyn; Ikonomidou, Vasiliki

2017-05-01

Heart rate measurement using a visual spectrum recording of the face has drawn interest over the last few years as a technology that can have various health and security applications. In our previous work, we have shown that it is possible to estimate the heart beat timing accurately enough to perform heart rate variability analysis for contactless stress detection. However, a major confounding factor in this approach is the presence of movement, which can interfere with the measurements. To mitigate the effects of movement, in this work we propose the use of face detection and tracking based on the Karhunen-Loewe algorithm in order to counteract measurement errors introduced by normal subject motion, as expected during a common seated conversation setting. We analyze the requirements on image acquisition for the algorithm to work, and its performance under different ranges of motion, changes of distance to the camera, as well and the effect of illumination changes due to different positioning with respect to light sources on the acquired signal. Our results suggest that the effect of face tracking on visual-spectrum based cardiac signal estimation depends on the amplitude of the motion. While for larger-scale conversation-induced motion it can significantly improve estimation accuracy, with smaller-scale movements, such as the ones caused by breathing or talking without major movement errors in facial tracking may interfere with signal estimation. Overall, employing facial tracking is a crucial step in adapting this technology to real-life situations with satisfactory results.

Development of 4D mathematical observer models for the task-based evaluation of gated myocardial perfusion SPECT

NASA Astrophysics Data System (ADS)

Lee, Taek-Soo; Frey, Eric C.; Tsui, Benjamin M. W.

2015-04-01

This paper presents two 4D mathematical observer models for the detection of motion defects in 4D gated medical images. Their performance was compared with results from human observers in detecting a regional motion abnormality in simulated 4D gated myocardial perfusion (MP) SPECT images. The first 4D mathematical observer model extends the conventional channelized Hotelling observer (CHO) based on a set of 2D spatial channels and the second is a proposed model that uses a set of 4D space-time channels. Simulated projection data were generated using the 4D NURBS-based cardiac-torso (NCAT) phantom with 16 gates/cardiac cycle. The activity distribution modelled uptake of 99mTc MIBI with normal perfusion and a regional wall motion defect. An analytical projector was used in the simulation and the filtered backprojection (FBP) algorithm was used in image reconstruction followed by spatial and temporal low-pass filtering with various cut-off frequencies. Then, we extracted 2D image slices from each time frame and reorganized them into a set of cine images. For the first model, we applied 2D spatial channels to the cine images and generated a set of feature vectors that were stacked for the images from different slices of the heart. The process was repeated for each of the 1,024 noise realizations, and CHO and receiver operating characteristics (ROC) analysis methodologies were applied to the ensemble of the feature vectors to compute areas under the ROC curves (AUCs). For the second model, a set of 4D space-time channels was developed and applied to the sets of cine images to produce space-time feature vectors to which the CHO methodology was applied. The AUC values of the second model showed better agreement (Spearman’s rank correlation (SRC) coefficient = 0.8) to human observer results than those from the first model (SRC coefficient = 0.4). The agreement with human observers indicates the proposed 4D mathematical observer model provides a good predictor of the performance of human observers in detecting regional motion defects in 4D gated MP SPECT images. The result supports the use of the observer model in the optimization and evaluation of 4D image reconstruction and compensation methods for improving the detection of motion abnormalities in 4D gated MP SPECT images.

Motion-corrected whole-heart PET-MR for the simultaneous visualisation of coronary artery integrity and myocardial viability: an initial clinical validation.

PubMed

Munoz, Camila; Kunze, Karl P; Neji, Radhouene; Vitadello, Teresa; Rischpler, Christoph; Botnar, René M; Nekolla, Stephan G; Prieto, Claudia

2018-05-12

Cardiac PET-MR has shown potential for the comprehensive assessment of coronary heart disease. However, image degradation due to physiological motion remains a challenge that could hinder the adoption of this technology in clinical practice. The purpose of this study was to validate a recently proposed respiratory motion-corrected PET-MR framework for the simultaneous visualisation of myocardial viability ( 18 F-FDG PET) and coronary artery anatomy (coronary MR angiography, CMRA) in patients with chronic total occlusion (CTO). A cohort of 14 patients was scanned with the proposed PET-CMRA framework. PET and CMRA images were reconstructed with and without the proposed motion correction approach for comparison purposes. Metrics of image quality including visible vessel length and sharpness were obtained for CMRA for both the right and left anterior descending coronary arteries (RCA, LAD), and relative increase in 18 F-FDG PET signal after motion correction for standard 17-segment polar maps was computed. Resulting coronary anatomy by CMRA and myocardial integrity by PET were visually compared against X-ray angiography and conventional Late Gadolinium Enhancement (LGE) MRI, respectively. Motion correction increased CMRA visible vessel length by 49.9% and 32.6% (RCA, LAD) and vessel sharpness by 12.3% and 18.9% (RCA, LAD) on average compared to uncorrected images. Coronary lumen delineation on motion-corrected CMRA images was in good agreement with X-ray angiography findings. For PET, motion correction resulted in an average 8% increase in 18 F-FDG signal in the inferior and inferolateral segments of the myocardial wall. An improved delineation of myocardial viability defects and reduced noise in the 18 F-FDG PET images was observed, improving correspondence to subendocardial LGE-MRI findings compared to uncorrected images. The feasibility of the PET-CMRA framework for simultaneous cardiac PET-MR imaging in a short and predictable scan time (~11 min) has been demonstrated in 14 patients with CTO. Motion correction increased visible length and sharpness of the coronary arteries by CMRA, and improved delineation of the myocardium by 18 F-FDG PET, resulting in good agreement with X-ray angiography and LGE-MRI.

Comparison of treadmill exercise stress cardiac MRI to stress echocardiography in healthy volunteers for adequacy of left ventricular endocardial wall visualization: A pilot study

PubMed Central

Thavendiranathan, Paaladinesh; Dickerson, Jennifer A.; Scandling, Debbie; Balasubramanian, Vijay; Pennell, Michael L.; Hinton, Alice; Raman, Subha V.; Simonetti, Orlando P.

2013-01-01

Purpose To compare exercise stress cardiac magnetic resonance (cardiac MR) to echocardiography in healthy volunteers with respect to adequacy of endocardial visualization and confidence of stress study interpretation. Materials and Methods 28 healthy volunteers (aged 28 ± 11 years, 15 males) underwent exercise stress echo and cardiac MR one week apart assigned randomly to one test first. Stress cardiac MR was performed using an MRI-compatible treadmill; stress echo was performed as per routine protocol. Cardiac MR and echo images were independently reviewed and scored for adequacy of endocardial visualization and confidence in interpretation of the stress study. Results Heart rate at the time of imaging was similar between the studies. Average time from cessation of exercise to start of imaging (21 vs. 31 seconds, p<0.001) and time to acquire stress images (20 vs. 51 seconds, p<0.001) was shorter for cardiac MR. The number of myocardial segments adequately visualized was significantly higher by cardiac MR at rest (99.8% versus 96.4%, p=0.002) and stress (99.8% versus 94.1%, p=0.001). The proportion of subjects in whom there was high confidence in the interpretation was higher for cardiac MR than echo (96% vs 60%, p=0.005). Conclusion Exercise stress cardiac MR to assess peak exercise wall motion is feasible and can be performed at least as rapidly as stress echo. PMID:24123562

Free-breathing diffusion tensor imaging and tractography of the human heart in healthy volunteers using wavelet-based image fusion.

PubMed

Wei, Hongjiang; Viallon, Magalie; Delattre, Benedicte M A; Moulin, Kevin; Yang, Feng; Croisille, Pierre; Zhu, Yuemin

2015-01-01

Free-breathing cardiac diffusion tensor imaging (DTI) is a promising but challenging technique for the study of fiber structures of the human heart in vivo. This work proposes a clinically compatible and robust technique to provide three-dimensional (3-D) fiber architecture properties of the human heart. To this end, 10 short-axis slices were acquired across the entire heart using a multiple shifted trigger delay (TD) strategy under free breathing conditions. Interscan motion was first corrected automatically using a nonrigid registration method. Then, two post-processing schemes were optimized and compared: an algorithm based on principal component analysis (PCA) filtering and temporal maximum intensity projection (TMIP), and an algorithm that uses the wavelet-based image fusion (WIF) method. The two methods were applied to the registered diffusion-weighted (DW) images to cope with intrascan motion-induced signal loss. The tensor fields were finally calculated, from which fractional anisotropy (FA), mean diffusivity (MD), and 3-D fiber tracts were derived and compared. The results show that the comparison of the FA values (FA(PCATMIP) = 0.45 ±0.10, FA(WIF) = 0.42 ±0.05, P=0.06) showed no significant difference, while the MD values ( MD(PCATMIP)=0.83 ±0.12×10(-3) mm (2)/s, MD(WIF)=0.74±0.05×10(-3) mm (2)/s, P=0.028) were significantly different. Improved helix angle variations through the myocardium wall reflecting the rotation characteristic of cardiac fibers were observed with WIF. This study demonstrates that the combination of multiple shifted TD acquisitions and dedicated post-processing makes it feasible to retrieve in vivo cardiac tractographies from free-breathing DTI acquisitions. The substantial improvements were observed using the WIF method instead of the previously published PCATMIP technique.

Two-dimensional XD-GRASP provides better image quality than conventional 2D cardiac cine MRI for patients who cannot suspend respiration.

PubMed

Piekarski, Eve; Chitiboi, Teodora; Ramb, Rebecca; Latson, Larry A; Bhatla, Puneet; Feng, Li; Axel, Leon

2018-02-01

Residual respiratory motion degrades image quality in conventional cardiac cine MRI (CCMRI). We evaluated whether a free-breathing (FB) radial imaging CCMRI sequence with compressed sensing reconstruction [extradimensional (e.g. cardiac and respiratory phases) golden-angle radial sparse parallel, or XD-GRASP] could provide better image quality than a conventional Cartesian breath-held (BH) sequence in an unselected population of patients undergoing clinical CCMRI. One hundred one patients who underwent BH and FB imaging in a midventricular short-axis plane at a matching location were included. Visual and quantitative image analysis was performed by two blinded experienced readers, using a five-point qualitative scale to score overall image quality and visual signal-to-noise ratio (SNR) grade, with measures of noise and sharpness. End-diastolic and end-systolic left ventricular areas were also measured and compared for both BH and FB images. Image quality was generally better with the BH cines (overall quality grade for BH vs FB images 4 vs 2.9, p < 0.001; noise 0.06 vs 0.08 p < 0.001; SNR grade 4.1 vs 3, p < 0.001), except for sharpness (p = 0.48). There were no significant differences between BH and FB images regarding end-diastolic or end-systolic areas (p = 0.35 and p = 0.12). Eighteen of the 101 patients had poor BH image quality (grade 1 or 2). In this subgroup, the quality of the FB images was better (p = 0.0032), as was the SNR grade (p = 0.003), but there were no significant differences regarding noise and sharpness (p = 0.45 and p = 0.47). Although FB XD-GRASP CCMRI was visually inferior to conventional BH CCMRI in general, it provided improved image quality in the subgroup of patients with respiratory-motion-induced artifacts on BH images.

Feature-based respiratory motion tracking in native fluoroscopic sequences for dynamic roadmaps during minimally invasive procedures in the thorax and abdomen

NASA Astrophysics Data System (ADS)

Wagner, Martin G.; Laeseke, Paul F.; Schubert, Tilman; Slagowski, Jordan M.; Speidel, Michael A.; Mistretta, Charles A.

2017-03-01

Fluoroscopic image guidance for minimally invasive procedures in the thorax and abdomen suffers from respiratory and cardiac motion, which can cause severe subtraction artifacts and inaccurate image guidance. This work proposes novel techniques for respiratory motion tracking in native fluoroscopic images as well as a model based estimation of vessel deformation. This would allow compensation for respiratory motion during the procedure and therefore simplify the workflow for minimally invasive procedures such as liver embolization. The method first establishes dynamic motion models for both the contrast-enhanced vasculature and curvilinear background features based on a native (non-contrast) and a contrast-enhanced image sequence acquired prior to device manipulation, under free breathing conditions. The model of vascular motion is generated by applying the diffeomorphic demons algorithm to an automatic segmentation of the subtraction sequence. The model of curvilinear background features is based on feature tracking in the native sequence. The two models establish the relationship between the respiratory state, which is inferred from curvilinear background features, and the vascular morphology during that same respiratory state. During subsequent fluoroscopy, curvilinear feature detection is applied to determine the appropriate vessel mask to display. The result is a dynamic motioncompensated vessel mask superimposed on the fluoroscopic image. Quantitative evaluation of the proposed methods was performed using a digital 4D CT-phantom (XCAT), which provides realistic human anatomy including sophisticated respiratory and cardiac motion models. Four groups of datasets were generated, where different parameters (cycle length, maximum diaphragm motion and maximum chest expansion) were modified within each image sequence. Each group contains 4 datasets consisting of the initial native and contrast enhanced sequences as well as a sequence, where the respiratory motion is tracked. The respiratory motion tracking error was between 1.00 % and 1.09 %. The estimated dynamic vessel masks yielded a Sørensen-Dice coefficient between 0.94 and 0.96. Finally, the accuracy of the vessel contours was measured in terms of the 99th percentile of the error, which ranged between 0.64 and 0.96 mm. The presented results show that the approach is feasible for respiratory motion tracking and compensation and could therefore considerably improve the workflow of minimally invasive procedures in the thorax and abdomen

Strain-Encoded Cardiac Magnetic Resonance Imaging as an Adjunct for Dobutamine Stress Testing. Incremental Value to Conventional Wall Motion Analysis

PubMed Central

Korosoglou, Grigorios; Lossnitzer, Dirk; Schellberg, Dieter; Lewien, Antje; Wochele, Angela; Schaeufele, Tim; Neizel, Mirja; Steen, Henning; Giannitsis, Evangelos; Katus, Hugo A.; Osman, Nael F.

2009-01-01

Background High-dose dobutamine stress magnetic resonance imaging (DS-MRI) is safe and feasible for the diagnosis of coronary artery disease (CAD) in humans. However, the assessment of cine scans relies on the visual interpretation of regional wall motion, which is subjective. Recently, Strain-Encoded MRI (SENC) has been proposed for the direct color-coded visualization of myocardial strain. The purpose of our study was to compare the diagnostic value of SENC to that provided by conventional wall motion analysis for the detection of inducible ischemia during DS-MRI. Methods and Results Stress induced ischemia was assessed by wall motion analysis and by SENC in 101 patients with suspected or known CAD and in 17 healthy volunteers who underwent DS-MRI in a clinical 1.5T scanner. Quantitative coronary angiography deemed as the standard reference for the presence or absence of significant CAD (≥50% diameter stenosis). On a coronary vessel level, SENC detected inducible ischemia in 86/101 versus 71/101 diseased coronary vessels (p<0.01 versus cine), and showed normal strain response in 189/202 versus 194/202 vessels with <50% stenosis (p=NS versus cine). On a patient level, SENC detected inducible ischemia in 63/64 versus 55/64 patients with CAD (p<0.05 versus cine), and showed normal strain response in 32/37 versus 34/37 patients without CAD (p=NS versus cine).Quantification analysis demonstrated a significant correlation between strain rate reserve (SRreserve) and coronary artery stenosis severity (r²=0.56, p<0.001), and a cut-off value of SRreserve=1.64 deemed as a highly accurate marker for the detection of stenosis≥50% (AUC=0.96, SE=0.01, 95% CI = 0.94–0.98, p<0.001). Conclusions The direct color-coded visualization of strain on MR-images is a useful adjunct for DS-MRI, which provides incremental value for the detection of CAD compared to conventional wall motion readings on cine images. PMID:19808579

Strain-encoded cardiac MRI as an adjunct for dobutamine stress testing: incremental value to conventional wall motion analysis.

PubMed

Korosoglou, Grigorios; Lossnitzer, Dirk; Schellberg, Dieter; Lewien, Antje; Wochele, Angela; Schaeufele, Tim; Neizel, Mirja; Steen, Henning; Giannitsis, Evangelos; Katus, Hugo A; Osman, Nael F

2009-03-01

High-dose dobutamine stress MRI is safe and feasible for the diagnosis of coronary artery disease (CAD) in humans. However, the assessment of cine scans relies on the visual interpretation of regional wall motion, which is subjective. Recently, strain-encoded MRI (SENC) has been proposed for the direct color-coded visualization of myocardial strain. The purpose of our study was to compare the diagnostic value of SENC with that provided by conventional wall motion analysis for the detection of inducible ischemia during dobutamine stress MRI. Stress-induced ischemia was assessed by wall motion analysis and by SENC in 101 patients with suspected or known CAD and in 17 healthy volunteers who underwent dobutamine stress MRI in a clinical 1.5-T scanner. Quantitative coronary angiography deemed as the standard reference for the presence or absence of significant CAD (> or =50% diameter stenosis). On a coronary vessel level, SENC detected inducible ischemia in 86 of 101 versus 71 of 101 diseased coronary vessels (P<0.01 versus cine) and showed normal strain response in 189 of 202 versus 194 of 202 vessels with <50% stenosis (P=NS versus cine). On a patient level, SENC detected inducible ischemia in 63 of 64 versus 55 of 64 patients with CAD (P<0.05 versus cine) and showed normal strain response in 32 of 37 versus 34 of 37 patients without CAD (P=NS versus cine). Quantification analysis demonstrated a significant correlation between strain rate reserve and coronary artery stenosis severity (r(2)=0.56, P<0.001), and a cutoff value of strain rate reserve of 1.64 was deemed as a highly accurate marker for the detection of > or =50% stenosis (area under the curve, 0.96; SE, 0.01; 95% CI, 0.94 to 0.98; P<0.001). The direct color-coded visualization of strain on MR images is a useful adjunct for dobutamine stress MRI, which provides incremental value for the detection of CAD compared with conventional wall motion readings on cine images.

Evaluation of motion artifact metrics for coronary CT angiography.

PubMed

Ma, Hongfeng; Gros, Eric; Szabo, Aniko; Baginski, Scott G; Laste, Zachary R; Kulkarni, Naveen M; Okerlund, Darin; Schmidt, Taly G

2018-02-01

This study quantified the performance of coronary artery motion artifact metrics relative to human observer ratings. Motion artifact metrics have been used as part of motion correction and best-phase selection algorithms for Coronary Computed Tomography Angiography (CCTA). However, the lack of ground truth makes it difficult to validate how well the metrics quantify the level of motion artifact. This study investigated five motion artifact metrics, including two novel metrics, using a dynamic phantom, clinical CCTA images, and an observer study that provided ground-truth motion artifact scores from a series of pairwise comparisons. Five motion artifact metrics were calculated for the coronary artery regions on both phantom and clinical CCTA images: positivity, entropy, normalized circularity, Fold Overlap Ratio (FOR), and Low-Intensity Region Score (LIRS). CT images were acquired of a dynamic cardiac phantom that simulated cardiac motion and contained six iodine-filled vessels of varying diameter and with regions of soft plaque and calcifications. Scans were repeated with different gantry start angles. Images were reconstructed at five phases of the motion cycle. Clinical images were acquired from 14 CCTA exams with patient heart rates ranging from 52 to 82 bpm. The vessel and shading artifacts were manually segmented by three readers and combined to create ground-truth artifact regions. Motion artifact levels were also assessed by readers using a pairwise comparison method to establish a ground-truth reader score. The Kendall's Tau coefficients were calculated to evaluate the statistical agreement in ranking between the motion artifacts metrics and reader scores. Linear regression between the reader scores and the metrics was also performed. On phantom images, the Kendall's Tau coefficients of the five motion artifact metrics were 0.50 (normalized circularity), 0.35 (entropy), 0.82 (positivity), 0.77 (FOR), 0.77(LIRS), where higher Kendall's Tau signifies higher agreement. The FOR, LIRS, and transformed positivity (the fourth root of the positivity) were further evaluated in the study of clinical images. The Kendall's Tau coefficients of the selected metrics were 0.59 (FOR), 0.53 (LIRS), and 0.21 (Transformed positivity). In the study of clinical data, a Motion Artifact Score, defined as the product of FOR and LIRS metrics, further improved agreement with reader scores, with a Kendall's Tau coefficient of 0.65. The metrics of FOR, LIRS, and the product of the two metrics provided the highest agreement in motion artifact ranking when compared to the readers, and the highest linear correlation to the reader scores. The validated motion artifact metrics may be useful for developing and evaluating methods to reduce motion in Coronary Computed Tomography Angiography (CCTA) images. © 2017 American Association of Physicists in Medicine.

Coupling reconstruction and motion estimation for dynamic MRI through optical flow constraint

NASA Astrophysics Data System (ADS)

Zhao, Ningning; O'Connor, Daniel; Gu, Wenbo; Ruan, Dan; Basarab, Adrian; Sheng, Ke

2018-03-01

This paper addresses the problem of dynamic magnetic resonance image (DMRI) reconstruction and motion estimation jointly. Because of the inherent anatomical movements in DMRI acquisition, reconstruction of DMRI using motion estimation/compensation (ME/MC) has been explored under the compressed sensing (CS) scheme. In this paper, by embedding the intensity based optical flow (OF) constraint into the traditional CS scheme, we are able to couple the DMRI reconstruction and motion vector estimation. Moreover, the OF constraint is employed in a specific coarse resolution scale in order to reduce the computational complexity. The resulting optimization problem is then solved using a primal-dual algorithm due to its efficiency when dealing with nondifferentiable problems. Experiments on highly accelerated dynamic cardiac MRI with multiple receiver coils validate the performance of the proposed algorithm.

SU-F-J-138: An Extension of PCA-Based Respiratory Deformation Modeling Via Multi-Linear Decomposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Iliopoulos, AS; Sun, X; Pitsianis, N

Purpose: To address and lift the limited degree of freedom (DoF) of globally bilinear motion components such as those based on principal components analysis (PCA), for encoding and modeling volumetric deformation motion. Methods: We provide a systematic approach to obtaining a multi-linear decomposition (MLD) and associated motion model from deformation vector field (DVF) data. We had previously introduced MLD for capturing multi-way relationships between DVF variables, without being restricted by the bilinear component format of PCA-based models. PCA-based modeling is commonly used for encoding patient-specific deformation as per planning 4D-CT images, and aiding on-board motion estimation during radiotherapy. However, themore » bilinear space-time decomposition inherently limits the DoF of such models by the small number of respiratory phases. While this limit is not reached in model studies using analytical or digital phantoms with low-rank motion, it compromises modeling power in the presence of relative motion, asymmetries and hysteresis, etc, which are often observed in patient data. Specifically, a low-DoF model will spuriously couple incoherent motion components, compromising its adaptability to on-board deformation changes. By the multi-linear format of extracted motion components, MLD-based models can encode higher-DoF deformation structure. Results: We conduct mathematical and experimental comparisons between PCA- and MLD-based models. A set of temporally-sampled analytical trajectories provides a synthetic, high-rank DVF; trajectories correspond to respiratory and cardiac motion factors, including different relative frequencies and spatial variations. Additionally, a digital XCAT phantom is used to simulate a lung lesion deforming incoherently with respect to the body, which adheres to a simple respiratory trend. In both cases, coupling of incoherent motion components due to a low model DoF is clearly demonstrated. Conclusion: Multi-linear decomposition can enable decoupling of distinct motion factors in high-rank DVF measurements. This may improve motion model expressiveness and adaptability to on-board deformation, aiding model-based image reconstruction for target verification. NIH Grant No. R01-184173.« less

Correction of motion artifacts in endoscopic optical coherence tomography and autofluorescence images based on azimuthal en face image registration.

PubMed

Abouei, Elham; Lee, Anthony M D; Pahlevaninezhad, Hamid; Hohert, Geoffrey; Cua, Michelle; Lane, Pierre; Lam, Stephen; MacAulay, Calum

2018-01-01

We present a method for the correction of motion artifacts present in two- and three-dimensional in vivo endoscopic images produced by rotary-pullback catheters. This method can correct for cardiac/breathing-based motion artifacts and catheter-based motion artifacts such as nonuniform rotational distortion (NURD). This method assumes that en face tissue imaging contains slowly varying structures that are roughly parallel to the pullback axis. The method reduces motion artifacts using a dynamic time warping solution through a cost matrix that measures similarities between adjacent frames in en face images. We optimize and demonstrate the suitability of this method using a real and simulated NURD phantom and in vivo endoscopic pulmonary optical coherence tomography and autofluorescence images. Qualitative and quantitative evaluations of the method show an enhancement of the image quality. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Novel MRI-derived quantitative biomarker for cardiac function applied to classifying ischemic cardiomyopathy within a Bayesian rule learning framework

NASA Astrophysics Data System (ADS)

Menon, Prahlad G.; Morris, Lailonny; Staines, Mara; Lima, Joao; Lee, Daniel C.; Gopalakrishnan, Vanathi

2014-03-01

Characterization of regional left ventricular (LV) function may have application in prognosticating timely response and informing choice therapy in patients with ischemic cardiomyopathy. The purpose of this study is to characterize LV function through a systematic analysis of 4D (3D + time) endocardial motion over the cardiac cycle in an effort to define objective, clinically useful metrics of pathological remodeling and declining cardiac performance, using standard cardiac MRI data for two distinct patient cohorts accessed from CardiacAtlas.org: a) MESA - a cohort of asymptomatic patients; and b) DETERMINE - a cohort of symptomatic patients with a history of ischemic heart disease (IHD) or myocardial infarction. The LV endocardium was segmented and a signed phase-to-phase Hausdorff distance (HD) was computed at 3D uniformly spaced points tracked on segmented endocardial surface contours, over the cardiac cycle. An LV-averaged index of phase-to-phase endocardial displacement (P2PD) time-histories was computed at each tracked point, using the HD computed between consecutive cardiac phases. Average and standard deviation in P2PD over the cardiac cycle was used to prepare characteristic curves for the asymptomatic and IHD cohort. A novel biomarker of RMS error between mean patient-specific characteristic P2PD over the cardiac cycle for each individual patient and the cumulative P2PD characteristic of a cohort of asymptomatic patients was established as the RMS-P2PD marker. The novel RMS-P2PD marker was tested as a cardiac function based feature for automatic patient classification using a Bayesian Rule Learning (BRL) framework. The RMS-P2PD biomarker indices were significantly different for the symptomatic patient and asymptomatic control cohorts (p<0.001). BRL accurately classified 83.8% of patients correctly from the patient and control populations, with leave-one-out cross validation, using standard indices of LV ejection fraction (LV-EF) and LV end-systolic volume index (LV-ESVI). This improved to 91.9% with inclusion of the RMS-P2PD biomarker and was congruent with improvements in both sensitivity for classifying patients and specificity for identifying asymptomatic controls from 82.6% up to 95.7%. RMS-P2PD, when contrasted against a collective normal reference, is a promising biomarker to investigate further in its utility for identifying quantitative signs of pathological endocardial function which may boost standard image makers as precursors of declining cardiac performance.

A new algorithm for segmentation of cardiac quiescent phases and cardiac time intervals using seismocardiography

NASA Astrophysics Data System (ADS)

Jafari Tadi, Mojtaba; Koivisto, Tero; Pänkäälä, Mikko; Paasio, Ari; Knuutila, Timo; Teräs, Mika; Hänninen, Pekka

2015-03-01

Systolic time intervals (STI) have significant diagnostic values for a clinical assessment of the left ventricle in adults. This study was conducted to explore the feasibility of using seismocardiography (SCG) to measure the systolic timings of the cardiac cycle accurately. An algorithm was developed for the automatic localization of the cardiac events (e.g. the opening and closing moments of the aortic and mitral valves). Synchronously acquired SCG and electrocardiography (ECG) enabled an accurate beat to beat estimation of the electromechanical systole (QS2), pre-ejection period (PEP) index and left ventricular ejection time (LVET) index. The performance of the algorithm was evaluated on a healthy test group with no evidence of cardiovascular disease (CVD). STI values were corrected based on Weissler's regression method in order to assess the correlation between the heart rate and STIs. One can see from the results that STIs correlate poorly with the heart rate (HR) on this test group. An algorithm was developed to visualize the quiescent phases of the cardiac cycle. A color map displaying the magnitude of SCG accelerations for multiple heartbeats visualizes the average cardiac motions and thereby helps to identify quiescent phases. High correlation between the heart rate and the duration of the cardiac quiescent phases was observed.

Human relaxin gene expression delivered by bioreducible dendrimer polymer for post-infarct cardiac remodeling in rats

PubMed Central

Lee, Young Sook; Choi, Joung-Woo; Oh, Jung-Eun; Yun, Chae-Ok; Kim, Sung Wan

2017-01-01

In consensus, myocardial infarction (MI) is defined as irreversible cell death secondary to prolonged ischemia in heart. The aim of our study was to evaluate the therapeutic potential of anti-fibrotic human Relaxin-expressing plasmid DNA with hypoxia response element (HRE) 12 copies (HR1) delivered by a dendrimer type PAM-ABP polymer G0 (HR1/G0) after MI on functional, hemodynamic, geometric, and cardiac extracellular matrix (ECM) remodeling in rats. HR1/G0 demonstrated significantly improved LV systolic function, hemodynamic parameters, and geometry on 1 wk and 4 wks after MI in rats, compared with I/R group. The resolution of regional wall motional abnormalities and the increased blood flow of infarct-related coronary artery supported functional improvements of HR1/G0. Furthermore, HR1/G0 polyplex showed favorable post-infarct cardiac ECM remodeling reflected on the favorable cardiac ECM compositions. Overall, this is the first study, which presented an advanced platform for the gene therapy that reverses adverse cardiac remodeling after MI with a HR1 gene delivered by a bioreducible dendrimer polymer in the cardiac ECM. PMID:27174688

Comparison of water-based foam and carbon dioxide gas mass emergency depopulation of White Pekin ducks.

PubMed

Caputo, M P; Benson, E R; Pritchett, E M; Hougentogler, D P; Jain, P; Patil, C; Johnson, A L; Alphin, R L

2012-12-01

The mass depopulation of production birds remains an effective means of controlling fast-moving, highly infectious diseases such as avian influenza and virulent Newcastle disease. Two experiments were performed to compare the physiological responses of White Pekin commercial ducks during foam depopulation and CO(2) gas depopulation. Both experiment 1 (5 to 9 wk of age) and 2 (8 to 14 wk of age) used electroencephalogram, electrocardiogram, and accelerometer to monitor and evaluate the difference in time to unconsciousness, motion cessation, brain death, altered terminal cardiac activity, duration of bradycardia, and elapsed time from onset of bradycardia to onset of unconsciousness between foam and CO(2) gas. Experiment 2 also added a third treatment, foam + atropine injection, to evaluate the effect of suppressing bradycardia. Experiment 1 resulted in significantly shorter times for all 6 physiological points for CO(2) gas compared with foam, whereas experiment 2 found that there were no significant differences between foam and CO(2) gas for these physiological points except brain death, in which CO(2) was significantly faster than foam and duration of bradycardia, which was shorter for CO(2). Experiment 2 also determined there was a significant positive correlation between duration of bradycardia and time to unconsciousness, motion cessation, brain death, and altered terminal cardiac activity. The time to unconsciousness, motion cessation, brain death, and altered terminal cardiac activity was significantly faster for the treatment foam + atropine injection compared with foam. Both experiments showed that bradycardia can occur as a result of either submersion in foam or exposure to CO(2) gas. The duration of bradycardia has a significant impact on the time it takes White Pekin ducks to reach unconsciousness and death during depopulation.

High-Frame-Rate Speckle-Tracking Echocardiography.

PubMed

Joos, Philippe; Poree, Jonathan; Liebgott, Herve; Vray, Didier; Baudet, Mathilde; Faurie, Julia; Tournoux, Francois; Cloutier, Guy; Nicolas, Barbara; Garcia, Damien; Baudet, Mathilde; Tournoux, Francois; Joos, Philippe; Poree, Jonathan; Cloutier, Guy; Liebgott, Herve; Faurie, Julia; Vray, Didier; Nicolas, Barbara; Garcia, Damien

2018-05-01

Conventional echocardiography is the leading modality for noninvasive cardiac imaging. It has been recently illustrated that high-frame-rate echocardiography using diverging waves could improve cardiac assessment. The spatial resolution and contrast associated with this method are commonly improved by coherent compounding of steered beams. However, owing to fast tissue velocities in the myocardium, the summation process of successive diverging waves can lead to destructive interferences if motion compensation (MoCo) is not considered. Coherent compounding methods based on MoCo have demonstrated their potential to provide high-contrast B-mode cardiac images. Ultrafast speckle-tracking echocardiography (STE) based on common speckle-tracking algorithms could substantially benefit from this original approach. In this paper, we applied STE on high-frame-rate B-mode images obtained with a specific MoCo technique to quantify the 2-D motion and tissue velocities of the left ventricle. The method was first validated in vitro and then evaluated in vivo in the four-chamber view of 10 volunteers. High-contrast high-resolution B-mode images were constructed at 500 frames/s. The sequences were generated with a Verasonics scanner and a 2.5-MHz phased array. The 2-D motion was estimated with standard cross correlation combined with three different subpixel adjustment techniques. The estimated in vitro velocity vectors derived from STE were consistent with the expected values, with normalized errors ranging from 4% to 12% in the radial direction and from 10% to 20% in the cross-range direction. Global longitudinal strain of the left ventricle was also obtained from STE in 10 subjects and compared to the results provided by a clinical scanner: group means were not statistically different ( value = 0.33). The in vitro and in vivo results showed that MoCo enables preservation of the myocardial speckles and in turn allows high-frame-rate STE.

Conversion of umbilical arterial Doppler waveforms to cardiac cycle triggering signals: a preparatory study for online motion-gated three-dimensional fetal echocardiography.

PubMed

Deng, J; Birkett, A G; Kalache, K D; Hanson, M A; Peebles, D M; Linney, A D; Lees, W R; Rodeck, C H

2001-01-01

To remove motion artefacts, a device was built to convert "noisy" umbilical arterial Doppler waveforms (UADWs) from an ultrasound (US) system into sharp ECG R-wave-like cardiac cycle triggering signals (CCTSs). These CCTSs were then used to gate a simultaneous (online) 3-D acquisition of sectional fetal echocardiograms from another US system. To test the conversion performance, a study was carried out in sheep fetal twins. Pulmonary arterial flow waveforms (PAFWs) from implanted probes were traced, in the meantime, to determine the reference cardiac cycle. Interference caused by running the two nonsynchronised US systems was controlled to three degrees (not-noticeable, moderate, and severe), together with high (> or = 40 cm/s) and low (< 40) flow velocities on UADWs. The conversion efficiency, assessed by the percentage of UADWs converted into CCTSs, was in the range of 83% to 100% for not-noticeable and moderate interference, and 0% to 71% for severe interference. The triggering accuracy, assessed by [(time lag mean between the onsets of PAFWs and corresponding CCTSs) -- (its 99% confidence level)] / the mean, was 90% to 96% for the not-noticeable interference high- and low-flow groups and for the moderate interference high-flow group; 19% to 93% for the moderate interference low-flow group; and from not obtainable up to 90% for the severe interference groups. The results show that UADWs can be used as a satisfactory online motion-gating source even in the presence of moderate interference. The major problems are from severe interference or moderate interference with low-flow velocity, which can be minimised/eliminated by the integration of the individual systems involved.

4D micro-CT using fast prospective gating

NASA Astrophysics Data System (ADS)

Guo, Xiaolian; Johnston, Samuel M.; Qi, Yi; Johnson, G. Allan; Badea, Cristian T.

2012-01-01

Micro-CT is currently used in preclinical studies to provide anatomical information. But, there is also significant interest in using this technology to obtain functional information. We report here a new sampling strategy for 4D micro-CT for functional cardiac and pulmonary imaging. Rapid scanning of free-breathing mice is achieved with fast prospective gating (FPG) implemented on a field programmable gate array. The method entails on-the-fly computation of delays from the R peaks of the ECG signals or the peaks of the respiratory signals for the triggering pulses. Projection images are acquired for all cardiac or respiratory phases at each angle before rotating to the next angle. FPG can deliver the faster scan time of retrospective gating (RG) with the regular angular distribution of conventional prospective gating for cardiac or respiratory gating. Simultaneous cardio-respiratory gating is also possible with FPG in a hybrid retrospective/prospective approach. We have performed phantom experiments to validate the new sampling protocol and compared the results from FPG and RG in cardiac imaging of a mouse. Additionally, we have evaluated the utility of incorporating respiratory information in 4D cardiac micro-CT studies with FPG. A dual-source micro-CT system was used for image acquisition with pulsed x-ray exposures (80 kVp, 100 mA, 10 ms). The cardiac micro-CT protocol involves the use of a liposomal blood pool contrast agent containing 123 mg I ml-1 delivered via a tail vein catheter in a dose of 0.01 ml g-1 body weight. The phantom experiment demonstrates that FPG can distinguish the successive phases of phantom motion with minimal motion blur, and the animal study demonstrates that respiratory FPG can distinguish inspiration and expiration. 4D cardiac micro-CT imaging with FPG provides image quality superior to RG at an isotropic voxel size of 88 µm and 10 ms temporal resolution. The acquisition time for either sampling approach is less than 5 min. The radiation dose associated with the proposed method is in the range of a typical micro-CT dose (256 mGy for the cardiac study). Ignoring respiration does not significantly affect anatomic information in cardiac studies. FPG can deliver short scan times with low-dose 4D micro-CT imaging without sacrificing image quality. FPG can be applied in high-throughput longitudinal studies in a wide range of applications, including drug safety and cardiopulmonary phenotyping.

Endocardial Energy Harvesting by Electromagnetic Induction.

PubMed

Zurbuchen, Adrian; Haeberlin, Andreas; Bereuter, Lukas; Pfenniger, Alois; Bosshard, Simon; Kernen, Micha; Philipp Heinisch, Paul; Fuhrer, Juerg; Vogel, Rolf

2018-02-01

cardiac pacemakers require regular medical follow-ups to ensure proper functioning. However, device replacements due to battery depletion are common and account for ∼25% of all implantation procedures. Furthermore, conventional pacemakers require pacemaker leads which are prone to fractures, dislocations or isolation defects. The ensuing surgical interventions increase risks for the patients and costs that need to be avoided. in this study, we present a method to harvest energy from endocardial heart motions. We developed a novel generator, which converts the heart's mechanical into electrical energy by electromagnetic induction. A mathematical model has been introduced to identify design parameters strongly related to the energy conversion efficiency of heart motions and fit the geometrical constraints for a miniaturized transcatheter deployable device. The implemented final design was tested on the bench and in vivo. the mathematical model proved an accurate method to estimate the harvested energy. For three previously recorded heart motions, the model predicted a mean output power of 14.5, 41.9, and 16.9 μW. During an animal experiment, the implanted device harvested a mean output power of 0.78 and 1.7 μW at a heart rate of 84 and 160 bpm, respectively. harvesting kinetic energy from endocardial motions seems feasible. Implanted at an energetically favorable location, such systems might become a welcome alternative to extend the lifetime of cardiac implantable electronic device. the presented endocardial energy harvesting concept has the potential to turn pacemakers into battery- and leadless systems and thereby eliminate two major drawbacks of contemporary systems.

SVM-based classification of LV wall motion in cardiac MRI with the assessment of STE

NASA Astrophysics Data System (ADS)

Mantilla, Juan; Garreau, Mireille; Bellanger, Jean-Jacques; Paredes, José Luis

2015-01-01

In this paper, we propose an automated method to classify normal/abnormal wall motion in Left Ventricle (LV) function in cardiac cine-Magnetic Resonance Imaging (MRI), taking as reference, strain information obtained from 2D Speckle Tracking Echocardiography (STE). Without the need of pre-processing and by exploiting all the images acquired during a cardiac cycle, spatio-temporal profiles are extracted from a subset of radial lines from the ventricle centroid to points outside the epicardial border. Classical Support Vector Machines (SVM) are used to classify features extracted from gray levels of the spatio-temporal profile as well as their representations in the Wavelet domain under the assumption that the data may be sparse in that domain. Based on information obtained from radial strain curves in 2D-STE studies, we label all the spatio-temporal profiles that belong to a particular segment as normal if the peak systolic radial strain curve of this segment presents normal kinesis, or abnormal if the peak systolic radial strain curve presents hypokinesis or akinesis. For this study, short-axis cine- MR images are collected from 9 patients with cardiac dyssynchrony for which we have the radial strain tracings at the mid-papilary muscle obtained by 2D STE; and from one control group formed by 9 healthy subjects. The best classification performance is obtained with the gray level information of the spatio-temporal profiles using a RBF kernel with 91.88% of accuracy, 92.75% of sensitivity and 91.52% of specificity.

Dynamic four-dimensional computed tomography (4D CT) imaging for re-entry risk assessment in re-do sternotomy - first experience.

PubMed

Narayanan, Harish; Viana, Fabiano F; Smith, Julian A; Roumeliotis, Nicholas K; Troupis, Christopher J; Crossett, Marcus P; Troupis, John M

2015-10-01

Repeat cardiac surgeries are well known to have higher rates of complications, one of the important reasons being injuries associated with re-do sternotomy. Routine imaging with CT can help to minimise this risk by pre-operatively assessing the anatomical relation between the sternum and the underlying cardiovascular structures, but is limited by its inability to determine the presence and severity of functional tethering and adhesions between these structures. However, with the evolution of wide area detector MD CT scanners, it is possible to assess the presence of tethering using the dynamic four-dimensional CT (4D CT) imaging technique. Nineteen patients undergoing re-do cardiac surgery were pre-operatively imaged using dynamic 4D CT during regulated respiration. The datasets were assessed in cine mode for presence of differential motion between sternum and underlying cardiovascular structures which indicates lack of significant tethering. Overall, there was excellent correlation between preoperative imaging and intraoperative findings. The technique enabled our surgeons to meticulously plan the procedures and to avoid re-entry related injuries. Our initial experience shows that dynamic 4D CT is useful in risk stratification prior to re-do sternotomy by determining the presence or absence of tethering between sternum and underlying structures based on assessment of differential motion. Furthermore we determined the technique to be superior to non-dynamic assessment of retrocardiac tethering. Copyright © 2015 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

Abnormal stress echocardiography findings in cardiac amyloidosis.

PubMed

Ong, Kevin C; Askew, J Wells; Dispenzieri, Angela; Maleszewski, Joseph J; Klarich, Kyle W; Anavekar, Nandan S; Mulvagh, Sharon L; Grogan, Martha

2016-06-01

Cardiac involvement in immunoglobulin light chain (amyloid light chain, AL) amyloidosis is characterized by myocardial interstitial deposition but can also cause obstructive deposits in the coronary microvasculature. We retrospectively identified 20 patients who underwent stress echocardiography within 1 year prior to the histologic diagnosis of AL amyloidosis. Only patients with cardiac amyloidosis and no known obstructive coronary disease were included. Stress echocardiograms (13 exercise; 7 dobutamine) were performed for evaluation of dyspnea and/or chest pain. Stress-induced wall motion abnormalities (WMAs) occurred in 11 patients (55%), 4 of whom had normal left ventricular wall thickness. Coronary angiogram was performed in 9 of 11 patients and demonstrated no or mild epicardial coronary artery disease. Seven (54%) patients had an abnormal exercise blood pressure which occurred with similar likelihood between those with and without stress-induced WMAs. Stress-induced WMAs and abnormal exercise blood pressure may occur in patients with cardiac AL amyloidosis despite the absence of significant epicardial coronary artery disease. This finding should raise the possibility of cardiac amyloidosis even in the absence of significant myocardial thickening.

Contemporary review on the pathogenesis of takotsubo syndrome: The heart shedding tears: Norepinephrine churn and foam at the cardiac sympathetic nerve terminals.

PubMed

Y-Hassan, Shams; De Palma, Rodney

2017-02-01

Takotsubo syndrome (TS), an increasingly recognized acute cardiac disease entity, is characterized by a unique pattern of circumferential and typically regional left ventricular wall motion abnormality resulting in a conspicuous transient ballooning of the left ventricle during systole. The mechanism of the disease remains elusive. However, the sudden onset of acute myocardial stunning in a systematic pattern extending beyond a coronary artery territory; the history of a preceding emotional or physical stress factor in two thirds of cases; the signs of sympathetic denervation at the regions of left ventricular dysfunction on sympathetic scintigraphy; the finding of myocardial edema and other signs consistent with (catecholamine-induced) myocarditis shown by cardiac magnetic resonance imaging; and the contraction band necrosis on histopathological examination all argue strongly for the involvement of the cardiac sympathetic nervous system in the pathogenesis of TS. In this narrative review, extensive evidence in support of local cardiac sympathetic nerve hyperactivation, disruption and norepinephrine spillover causing TS in predisposed patients is provided. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Advanced Echocardiography in Adult Zebrafish Reveals Delayed Recovery of Heart Function after Myocardial Cryoinjury

PubMed Central

Kossack, Mandy; Juergensen, Lonny; Fuchs, Dieter; Katus, Hugo A.; Hassel, David

2015-01-01

Translucent zebrafish larvae represent an established model to analyze genetics of cardiac development and human cardiac disease. More recently adult zebrafish are utilized to evaluate mechanisms of cardiac regeneration and by benefiting from recent genome editing technologies, including TALEN and CRISPR, adult zebrafish are emerging as a valuable in vivo model to evaluate novel disease genes and specifically validate disease causing mutations and their underlying pathomechanisms. However, methods to sensitively and non-invasively assess cardiac morphology and performance in adult zebrafish are still limited. We here present a standardized examination protocol to broadly assess cardiac performance in adult zebrafish by advancing conventional echocardiography with modern speckle-tracking analyses. This allows accurate detection of changes in cardiac performance and further enables highly sensitive assessment of regional myocardial motion and deformation in high spatio-temporal resolution. Combining conventional echocardiography measurements with radial and longitudinal velocity, displacement, strain, strain rate and myocardial wall delay rates after myocardial cryoinjury permitted to non-invasively determine injury dimensions and to longitudinally follow functional recovery during cardiac regeneration. We show that functional recovery of cryoinjured hearts occurs in three distinct phases. Importantly, the regeneration process after cryoinjury extends far beyond the proposed 45 days described for ventricular resection with reconstitution of myocardial performance up to 180 days post-injury (dpi). The imaging modalities evaluated here allow sensitive cardiac phenotyping and contribute to further establish adult zebrafish as valuable cardiac disease model beyond the larval developmental stage. PMID:25853735

The rf coil as a sensitive motion detector for magnetic resonance imaging.

PubMed

Buikman, D; Helzel, T; Röschmann, P

1988-01-01

A new sensor principle for detection of patient movement in magnetic resonance imaging has been successfully applied for the reduction of motion artifacts. It uses a device that is already present in every MRI system, namely the rf coil. Patient movement within the coil causes changes in the rf impedance match of the coil, which can be measured as variations in the reflected rf power. The principle used for the detection of respiratory and cardiac motion is described, and experimental results measured with several coil arrangements are given. Images are presented which were acquired with respiratory gating derived from the rf body coil of a 2 Tesla whole body MRI system.

Heartbeat OCT: in vivo intravascular megahertz-optical coherence tomography

PubMed Central

Wang, Tianshi; Pfeiffer, Tom; Regar, Evelyn; Wieser, Wolfgang; van Beusekom, Heleen; Lancee, Charles T.; Springeling, Geert; Krabbendam, Ilona; van der Steen, Antonius F.W.; Huber, Robert; van Soest, Gijs

2015-01-01

Cardiac motion artifacts, non-uniform rotational distortion and undersampling affect the image quality and the diagnostic impact of intravascular optical coherence tomography (IV-OCT). In this study we demonstrate how these limitations of IV-OCT can be addressed by using an imaging system that we called “Heartbeat OCT”, combining a fast Fourier Domain Mode Locked laser, fast pullback, and a micromotor actuated catheter, designed to examine a coronary vessel in less than one cardiac cycle. We acquired in vivo data sets of two coronary arteries in a porcine heart with both Heartbeat OCT, working at 2.88 MHz A-line rate, 4000 frames/s and 100 mm/s pullback speed, and with a commercial system. The in vivo results show that Heartbeat OCT provides faithfully rendered, motion-artifact free, fully sampled vessel wall architecture, unlike the conventional IV-OCT data. We present the Heartbeat OCT system in full technical detail and discuss the steps needed for clinical translation of the technology. PMID:26713214

Ventricular dysfunction in children with obstructive sleep apnea: radionuclide assessment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tal, A.; Leiberman, A.; Margulis, G.

Ventricular function was evaluated using radionuclide ventriculography in 27 children with oropharyngeal obstruction and clinical features of obstructive sleep apnea. Their mean age was 3.5 years (9 months to 7.5 years). Conventional clinical assessment did not detect cardiac involvement in 25 of 27 children; however, reduced right ventricular ejection fraction (less than 35%) was found in 10 (37%) patients (mean: 19.5 +/- 2.3% SE, range: 8-28%). In 18 patients wall motion abnormality was detected. In 11 children in whom radionuclide ventriculography was performed before and after adenotonsillectomy, right ventricular ejection fraction rose from 24.4 +/- 3.6% to 46.7 +/- 3.4%more » (P less than 0.005), and in all cases wall motion showed a definite improvement. In five children, left ventricular ejection fraction rose greater than 10% after removal of oropharyngeal obstruction. It is concluded that right ventricular function may be compromised in children with obstructive sleep apnea secondary to adenotonsillar hypertrophy, even before clinical signs of cardiac involvement are present.« less

Frequency of Inverted Electrocardiographic T Waves (Cerebral T Waves) in Patients With Acute Strokes and Their Relation to Left Ventricular Wall Motion Abnormalities.

PubMed

Stone, Jeremy; Mor-Avi, Victor; Ardelt, Agnieszka; Lang, Roberto M

2018-01-01

Transient, symmetric, and deep inverted electrocardiogram (ECG) T waves in the setting of stroke, commonly referred to as cerebral T waves, are rare, and the underlying mechanism is unclear. Our study aimed to test the hypothesis that cerebral T waves are associated with transient cardiac dysfunction. This retrospective study included 800 patients admitted with the primary diagnosis of hemorrhagic or ischemic stroke. ECGs were examined for cerebral T waves, defined as T-wave inversion of ≥5 mm depth in ≥4 contiguous precordial leads. Echocardiograms of those meeting these criteria were examined for the presence of left ventricular (LV) wall motion abnormalities. Follow-up evaluation included both ECG and echocardiogram. Of the 800 patients, 17 had cerebral T waves on ECG (2.1%). All 17 patients had ischemic strokes, of which 11 were in the middle cerebral artery distribution (65%), and 2 were cerebellar (12%), whereas the remaining 4 involved other locations. Follow-up ECG showed resolution of the T-wave changes in all 17 patients. Of these patients, 14 (82%) had normal wall motion, and 3 had transient wall motion abnormalities (18%). Two of these patients had Takotsubo-like cardiomyopathy with apical ballooning, and the third had globally reduced LV function. Coronary angiography showed no significant disease to explain the LV dysfunction. In summary, in our cohort of patients with acute stroke, cerebral T waves were rare and occurred only in ischemic stroke. Eighteen percent of patients with cerebral T waves had significant transient wall motion abnormalities. Patients with stroke with cerebral T waves, especially in those with ischemic strokes, should be assessed for cardiac dysfunction. Copyright © 2017 Elsevier Inc. All rights reserved.

[Individual typological peculiarities of system blood flow, physical capacity for work and cardiac activity regulation in patients with different resistance to periodontal diseases].

PubMed

Bragin, A V

2008-01-01

From position of typological variability of physiological individuality concept-functional constitution types - the principle of organism integrity was substantiated for stomatological pathology. There were isolated typical and specific reactions of cardiac-vessel system in patients with different resistance to periodontal diseases. Each functional type - patients with different levels of usual motion activity - had their own physiological peculiarities of parameters of system blood flow, physical capacity for work and cardiac activity regulation, that determined individual typological organism reaction in cases of maxillo-facial system pathology. The received data gives the objective base for physiological approach to single out the extreme variants of norm for forming risk contingent and groups of resistant people to periodontal diseases.

Utility of cardiac computed tomography for evaluation of pannus in mechanical aortic valve.

PubMed

Suh, Young Joo; Kim, Young Jin; Lee, Sak; Hong, Yoo Jin; Lee, Hye-Jeong; Hur, Jin; Choi, Byoung Wook; Chang, Byung-Chul

2015-08-01

The clinical significance of pannus detected on computed tomography (CT) has not yet been investigated. The purposes of this study were to investigate the clinical significance of pannus detected on cardiac CT in patients who underwent aortic valve replacement (AVR) with mechanical valves, and to determine predictors for pannus severity. A total of 92 patients who underwent cardiac CT and TTE and who had undergone mechanical AVR were included. The geometric orifice area (GOA), the presence of limitation of motion (LOM) and pannus were evaluated on CT. The GOA, presence of LOM, and presence and severity of pannus were compared with echocardiographic parameters. Logistic regression analysis was performed to determine the predictors for pannus severity. The GOA on CT positively correlated with effective orifice area on TTE (r = 0.733, P < 0.0001). Pannus was found in 77.2% and LOM in 14.0%. With increasing pannus severity, mean transvalvular pressure gradient (PG) was significantly higher (P < 0.0001). Patients with elevated PG showed a smaller GOA, a higher incidence of pannus, more severe pannus and LOM than patients with normal PG (P < 0.05). Small valve size (≤19 mm), Carbomedics valve, rheumatic etiology, and young age at AVR (<48.8 years) were independent predictors of moderate to severe pannus (P < 0.05). Cardiac CT is helpful in the evaluation of pannus formation in patients with mechanical aortic valves. Moderate to severe pannus formation frequently occurred in patients with small mechanical valve size, Carbomedics valves, rheumatic heart disease and young age at AVR.

SiSSR: Simultaneous subdivision surface registration for the quantification of cardiac function from computed tomography in canines.

PubMed

Vigneault, Davis M; Pourmorteza, Amir; Thomas, Marvin L; Bluemke, David A; Noble, J Alison

2018-05-01

Recent improvements in cardiac computed tomography (CCT) allow for whole-heart functional studies to be acquired at low radiation dose (<2mSv) and high-temporal resolution (<100ms) in a single heart beat. Although the extraction of regional functional information from these images is of great clinical interest, there is a paucity of research into the quantification of regional function from CCT, contrasting with the large body of work in echocardiography and cardiac MR. Here we present the Simultaneous Subdivision Surface Registration (SiSSR) method: a fast, semi-automated image analysis pipeline for quantifying regional function from contrast-enhanced CCT. For each of thirteen adult male canines, we construct an anatomical reference mesh representing the left ventricular (LV) endocardium, obviating the need for a template mesh to be manually sculpted and initialized. We treat this generated mesh as a Loop subdivision surface, and adapt a technique previously described in the context of 3-D echocardiography to register these surfaces to the endocardium efficiently across all cardiac frames simultaneously. Although previous work performs the registration at a single resolution, we observe that subdivision surfaces naturally suggest a multiresolution approach, leading to faster convergence and avoiding local minima. We additionally make two notable changes to the cost function of the optimization, explicitly encouraging plausible biological motion and high mesh quality. Finally, we calculate an accepted functional metric for CCT from the registered surfaces, and compare our results to an alternate state-of-the-art CCT method. Published by Elsevier B.V.

Dynamic three-dimensional model of the coronary circulation

NASA Astrophysics Data System (ADS)

Lehmann, Glen; Gobbi, David G.; Dick, Alexander J.; Starreveld, Yves P.; Quantz, M.; Holdsworth, David W.; Drangova, Maria

2001-05-01

A realistic numerical three-dimensional (3D) model of the dynamics of human coronary arteries has been developed. High- resolution 3D images of the coronary arteries of an excised human heart were obtained using a C-arm based computed tomography (CT) system. Cine bi-plane coronary angiograms were then acquired from a patient with similar coronary anatomy. These angiograms were used to determine the vessel motion, which was applied to the static 3D coronary tree. Corresponding arterial bifurcations were identified in the 3D CT image and in the 2D angiograms. The 3D positions of the angiographic landmarks, which were known throughout the cardiac cycle, were used to warp the 3D image via a non-linear thin-plate spline algorithm. The result was a set or 30 dynamic volumetric images sampling a complete cardiac cycle. To the best of our knowledge, the model presented here is the first dynamic 3D model that provides a true representation of both the geometry and motion of a human coronary artery tree. In the future, similar models can be generated to represent different coronary anatomy and motion. Such models are expected to become an invaluable tool during the development of dynamic imaging techniques such as MRI, multi-slice CT and 3D angiography.

Dual gated PET/CT imaging of small targets of the heart: method description and testing with a dynamic heart phantom.

PubMed

Kokki, Tommi; Sipilä, Hannu T; Teräs, Mika; Noponen, Tommi; Durand-Schaefer, Nicolas; Klén, Riku; Knuuti, Juhani

2010-01-01

In PET imaging respiratory and cardiac contraction motions interfere the imaging of heart. The aim was to develop and evaluate dual gating method for improving the detection of small targets of the heart. The method utilizes two independent triggers which are sent periodically into list mode data based on respiratory and ECG cycles. An algorithm for generating dual gated segments from list mode data was developed. The test measurements showed that rotational and axial movements of point source can be separated spatially to different segments with well-defined borders. The effect of dual gating on detection of small moving targets was tested with a moving heart phantom. Dual gated images showed 51% elimination (3.6 mm out of 7.0 mm) of contraction motion of hot spot (diameter 3 mm) and 70% elimination (14 mm out of 20 mm) of respiratory motion. Averaged activity value of hot spot increases by 89% when comparing to non-gated images. Patient study of suspected cardiac sarcoidosis shows sharper spatial myocardial uptake profile and improved detection of small myocardial structures such as papillary muscles. The dual gating method improves detection of small moving targets in a phantom and it is feasible in clinical situations.

Sagittal fresh blood imaging with interleaved acquisition of systolic and diastolic data for improved robustness to motion.

PubMed

Atanasova, Iliyana P; Kim, Daniel; Storey, Pippa; Rosenkrantz, Andrew B; Lim, Ruth P; Lee, Vivian S

2013-02-01

To improve robustness to patient motion of "fresh blood imaging" (FBI) for lower extremity noncontrast MR angiography. In FBI, two sets of three-dimensional fast spin echo images are acquired at different cardiac phases and subtracted to generate bright-blood angiograms. Routinely performed with a single coronal slab and sequential acquisition of systolic and diastolic data, FBI is prone to subtraction errors due to patient motion. In this preliminary feasibility study, FBI was implemented with two sagittal imaging slabs, and the systolic and diastolic acquisitions were interleaved to minimize sensitivity to motion. The proposed technique was evaluated in volunteers and patients. In 10 volunteers, imaged while performing controlled movements, interleaved FBI demonstrated better tolerance to subject motion than sequential FBI. In one patient with peripheral arterial disease, interleaved FBI offered better depiction of collateral flow by reducing sensitivity to inadvertent motion. FBI with interleaved acquisition of diastolic and systolic data in two sagittal imaging slabs offers improved tolerance to patient motion. Copyright © 2013 Wiley Periodicals, Inc.

Sagittal Fresh Blood Imaging with Interleaved Acquisition of Systolic and Diastolic Data for Improved Robustness to Motion

PubMed Central

Atanasova, Iliyana P.; Kim, Daniel; Storey, Pippa; Rosenkrantz, Andrew B; Lim, Ruth P.; Lee, Vivian S.

2012-01-01

Purpose To improve robustness to patient motion of ‘fresh blood imaging’ (FBI) for lower extremity non-contrast MRA. Methods In FBI, two sets of 3D fast spin echo images are acquired at different cardiac phases and subtracted to generate bright-blood angiograms. Routinely performed with a single coronal slab and sequential acquisition of systolic and diastolic data, FBI is prone to subtraction errors due to patient motion. In this preliminary feasibility study, FBI was implemented with two sagittal imaging slabs, and the systolic and diastolic acquisitions were interleaved to minimize sensitivity to motion. The proposed technique was evaluated in volunteers and patients. Results In ten volunteers, imaged while performing controlled movements, interleaved FBI demonstrated better tolerance to subject motion than sequential FBI. In one patient with peripheral arterial disease, interleaved FBI offered better depiction of collateral flow by reducing sensitivity to inadvertent motion. Conclusions FBI with interleaved acquisition of diastolic and systolic data in two sagittal imaging slabs offers improved tolerance to patient motion. PMID:23300129

Tricuspid and Mitral Valve Regurgitation with Bi-fascicular Block Following a Horse Kick.

PubMed

Kokubun, Tomoki; Oikawa, Masayoshi; Ichijo, Yasuhiro; Matsumoto, Yoshiyuki; Yokokawa, Tetsuro; Nakazato, Kazuhiko; Sato, Yoshiyuki; Takase, Shinya; Shinjo, Hiroharu; Yokoyama, Hitoshi; Suzuki, Hitoshi; Saitoh, Shu-Ichi; Takeishi, Yasuchika

2018-06-01

A 40-year-old man was transferred to our hospital following an isolated horse kick injury to the anterior chest wall. The case showed bi-fascicular block, severe tricuspid valve regurgitation due to ruptured chordae tendineae of the anterior leaflet, moderate mitral valve regurgitation due to prolapse of mitral anterior leaflet, and hypokinetic motion of the inferior septal wall. Both tricuspid and mitral insufficiency were completely repaired by a surgical operation. Fortunately, these injuries were not fatal in this case, but the comprehensive assessment of cardiac damage and careful observation are important for managing patients with cardiac injury.

Registration of 4D cardiac CT sequences under trajectory constraints with multichannel diffeomorphic demons.

PubMed

Peyrat, Jean-Marc; Delingette, Hervé; Sermesant, Maxime; Xu, Chenyang; Ayache, Nicholas

2010-07-01

We propose a framework for the nonlinear spatiotemporal registration of 4D time-series of images based on the Diffeomorphic Demons (DD) algorithm. In this framework, the 4D spatiotemporal registration is decoupled into a 4D temporal registration, defined as mapping physiological states, and a 4D spatial registration, defined as mapping trajectories of physical points. Our contribution focuses more specifically on the 4D spatial registration that should be consistent over time as opposed to 3D registration that solely aims at mapping homologous points at a given time-point. First, we estimate in each sequence the motion displacement field, which is a dense representation of the point trajectories we want to register. Then, we perform simultaneously 3D registrations of corresponding time-points with the constraints to map the same physical points over time called the trajectory constraints. Under these constraints, we show that the 4D spatial registration can be formulated as a multichannel registration of 3D images. To solve it, we propose a novel version of the Diffeomorphic Demons (DD) algorithm extended to vector-valued 3D images, the Multichannel Diffeomorphic Demons (MDD). For evaluation, this framework is applied to the registration of 4D cardiac computed tomography (CT) sequences and compared to other standard methods with real patient data and synthetic data simulated from a physiologically realistic electromechanical cardiac model. Results show that the trajectory constraints act as a temporal regularization consistent with motion whereas the multichannel registration acts as a spatial regularization. Finally, using these trajectory constraints with multichannel registration yields the best compromise between registration accuracy, temporal and spatial smoothness, and computation times. A prospective example of application is also presented with the spatiotemporal registration of 4D cardiac CT sequences of the same patient before and after radiofrequency ablation (RFA) in case of atrial fibrillation (AF). The intersequence spatial transformations over a cardiac cycle allow to analyze and quantify the regression of left ventricular hypertrophy and its impact on the cardiac function.

The repeatability and characteristics of right ventricular longitudinal strain imaging by speckle-tracking echocardiography in healthy dogs.

PubMed

Morita, T; Nakamura, K; Osuga, T; Yokoyama, N; Khoirun, N; Morishita, K; Sasaki, N; Ohta, H; Takiguchi, M

2017-08-01

To assess the repeatability and characteristics of echocardiographic indices of the right ventricular (RV) function derived from speckle-tracking echocardiography. Fourteen laboratory Beagles and 103 privately owned dogs without cardiac disease were involved in this study. Right ventricular longitudinal strain, strain rate, and a strain-related index for assessing RV dyssynchrony derived from speckle-tracking echocardiography were obtained by two different observers using five Beagles. Within-day, between-day, and interobserver coefficients of variation and the intraclass correlation coefficient of speckle-tracking echocardiography indices were determined. Both speckle-tracking echocardiography and conventional indices of RV function, including the peak velocity of systolic tricuspid annular motion, tricuspid annulus plane systolic excursion, fractional area change, and the Tei index, were obtained from 14 Beagles and 103 privately owned dogs. Relationships between echocardiographic indices and the body weight, heart rate, age, and sex were estimated by regression analysis. Speckle-tracking echocardiographic indices showed good within-day repeatability, between-day and interobserver repeatability were moderate to good. In large dogs, RV longitudinal strain, strain rate, and fractional area change were significantly decreased, while the index of RV dyssynchrony, systolic tricuspid annular motion, tricuspid annulus plane systolic excursion, and the Tei index were increased. All speckle-tracking and conventional echocardiographic indices were correlated with the body weight. The speckle-tracking echocardiography indices were highly repeatable and body weight affected speckle-tracking echocardiography indices in dogs. Further studies are needed to apply speckle-tracking echocardiography indices in dogs with cardiac disease. Copyright © 2017 Elsevier B.V. All rights reserved.

A robust automated left ventricle region of interest localization technique using a cardiac cine MRI atlas

NASA Astrophysics Data System (ADS)

Ben-Zikri, Yehuda Kfir; Linte, Cristian A.

2016-03-01

Region of interest detection is a precursor to many medical image processing and analysis applications, including segmentation, registration and other image manipulation techniques. The optimal region of interest is often selected manually, based on empirical knowledge and features of the image dataset. However, if inconsistently identified, the selected region of interest may greatly affect the subsequent image analysis or interpretation steps, in turn leading to incomplete assessment during computer-aided diagnosis or incomplete visualization or identification of the surgical targets, if employed in the context of pre-procedural planning or image-guided interventions. Therefore, the need for robust, accurate and computationally efficient region of interest localization techniques is prevalent in many modern computer-assisted diagnosis and therapy applications. Here we propose a fully automated, robust, a priori learning-based approach that provides reliable estimates of the left and right ventricle features from cine cardiac MR images. The proposed approach leverages the temporal frame-to-frame motion extracted across a range of short axis left ventricle slice images with small training set generated from les than 10% of the population. This approach is based on histogram of oriented gradients features weighted by local intensities to first identify an initial region of interest depicting the left and right ventricles that exhibits the greatest extent of cardiac motion. This region is correlated with the homologous region that belongs to the training dataset that best matches the test image using feature vector correlation techniques. Lastly, the optimal left ventricle region of interest of the test image is identified based on the correlation of known ground truth segmentations associated with the training dataset deemed closest to the test image. The proposed approach was tested on a population of 100 patient datasets and was validated against the ground truth region of interest of the test images manually annotated by experts. This tool successfully identified a mask around the LV and RV and furthermore the minimal region of interest around the LV that fully enclosed the left ventricle from all testing datasets, yielding a 98% overlap with their corresponding ground truth. The achieved mean absolute distance error between the two contours that normalized by the radius of the ground truth is 0.20 +/- 0.09.

Cardiac-driven Pulsatile Motion of Intracranial Cerebrospinal Fluid Visualized Based on a Correlation Mapping Technique.

PubMed

Yatsushiro, Satoshi; Sunohara, Saeko; Hayashi, Naokazu; Hirayama, Akihiro; Matsumae, Mitsunori; Atsumi, Hideki; Kuroda, Kagayaki

2018-04-10

A correlation mapping technique delineating delay time and maximum correlation for characterizing pulsatile cerebrospinal fluid (CSF) propagation was proposed. After proofing its technical concept, this technique was applied to healthy volunteers and idiopathic normal pressure hydrocephalus (iNPH) patients. A time-resolved three dimensional-phase contrast (3D-PC) sampled the cardiac-driven CSF velocity at 32 temporal points per cardiac period at each spatial location using retrospective cardiac gating. The proposed technique visualized distributions of propagation delay and correlation coefficient of the PC-based CSF velocity waveform with reference to a waveform at a particular point in the CSF space. The delay time was obtained as the amount of time-shift, giving the maximum correlation for the velocity waveform at an arbitrary location with that at the reference location. The validity and accuracy of the technique were confirmed in a flow phantom equipped with a cardiovascular pump. The technique was then applied to evaluate the intracranial CSF motions in young, healthy (N = 13), and elderly, healthy (N = 13) volunteers and iNPH patients (N = 13). The phantom study demonstrated that root mean square error of the delay time was 2.27%, which was less than the temporal resolution of PC measurement used in this study (3.13% of a cardiac cycle). The human studies showed a significant difference (P < 0.01) in the mean correlation coefficient between the young, healthy group and the other two groups. A significant difference (P < 0.05) was also recognized in standard deviation of the correlation coefficients in intracranial CSF space among all groups. The result suggests that the CSF space compliance of iNPH patients was lower than that of healthy volunteers. The correlation mapping technique allowed us to visualize pulsatile CSF velocity wave propagations as still images. The technique may help to classify diseases related to CSF dynamics, such as iNPH.

Quantification of Global Diastolic Function by Kinematic Modeling-based Analysis of Transmitral Flow via the Parametrized Diastolic Filling Formalism

PubMed Central

Mossahebi, Sina; Zhu, Simeng; Chen, Howard; Shmuylovich, Leonid; Ghosh, Erina; Kovács, Sándor J.

2014-01-01

Quantitative cardiac function assessment remains a challenge for physiologists and clinicians. Although historically invasive methods have comprised the only means available, the development of noninvasive imaging modalities (echocardiography, MRI, CT) having high temporal and spatial resolution provide a new window for quantitative diastolic function assessment. Echocardiography is the agreed upon standard for diastolic function assessment, but indexes in current clinical use merely utilize selected features of chamber dimension (M-mode) or blood/tissue motion (Doppler) waveforms without incorporating the physiologic causal determinants of the motion itself. The recognition that all left ventricles (LV) initiate filling by serving as mechanical suction pumps allows global diastolic function to be assessed based on laws of motion that apply to all chambers. What differentiates one heart from another are the parameters of the equation of motion that governs filling. Accordingly, development of the Parametrized Diastolic Filling (PDF) formalism has shown that the entire range of clinically observed early transmitral flow (Doppler E-wave) patterns are extremely well fit by the laws of damped oscillatory motion. This permits analysis of individual E-waves in accordance with a causal mechanism (recoil-initiated suction) that yields three (numerically) unique lumped parameters whose physiologic analogues are chamber stiffness (k), viscoelasticity/relaxation (c), and load (xo). The recording of transmitral flow (Doppler E-waves) is standard practice in clinical cardiology and, therefore, the echocardiographic recording method is only briefly reviewed. Our focus is on determination of the PDF parameters from routinely recorded E-wave data. As the highlighted results indicate, once the PDF parameters have been obtained from a suitable number of load varying E-waves, the investigator is free to use the parameters or construct indexes from the parameters (such as stored energy 1/2kxo2, maximum A-V pressure gradient kxo, load independent index of diastolic function, etc.) and select the aspect of physiology or pathophysiology to be quantified. PMID:25226101

Quantification of global diastolic function by kinematic modeling-based analysis of transmitral flow via the parametrized diastolic filling formalism.

PubMed

Mossahebi, Sina; Zhu, Simeng; Chen, Howard; Shmuylovich, Leonid; Ghosh, Erina; Kovács, Sándor J

2014-09-01

Quantitative cardiac function assessment remains a challenge for physiologists and clinicians. Although historically invasive methods have comprised the only means available, the development of noninvasive imaging modalities (echocardiography, MRI, CT) having high temporal and spatial resolution provide a new window for quantitative diastolic function assessment. Echocardiography is the agreed upon standard for diastolic function assessment, but indexes in current clinical use merely utilize selected features of chamber dimension (M-mode) or blood/tissue motion (Doppler) waveforms without incorporating the physiologic causal determinants of the motion itself. The recognition that all left ventricles (LV) initiate filling by serving as mechanical suction pumps allows global diastolic function to be assessed based on laws of motion that apply to all chambers. What differentiates one heart from another are the parameters of the equation of motion that governs filling. Accordingly, development of the Parametrized Diastolic Filling (PDF) formalism has shown that the entire range of clinically observed early transmitral flow (Doppler E-wave) patterns are extremely well fit by the laws of damped oscillatory motion. This permits analysis of individual E-waves in accordance with a causal mechanism (recoil-initiated suction) that yields three (numerically) unique lumped parameters whose physiologic analogues are chamber stiffness (k), viscoelasticity/relaxation (c), and load (xo). The recording of transmitral flow (Doppler E-waves) is standard practice in clinical cardiology and, therefore, the echocardiographic recording method is only briefly reviewed. Our focus is on determination of the PDF parameters from routinely recorded E-wave data. As the highlighted results indicate, once the PDF parameters have been obtained from a suitable number of load varying E-waves, the investigator is free to use the parameters or construct indexes from the parameters (such as stored energy 1/2kxo(2), maximum A-V pressure gradient kxo, load independent index of diastolic function, etc.) and select the aspect of physiology or pathophysiology to be quantified.

Imaging in blunt cardiac injury: Computed tomographic findings in cardiac contusion and associated injuries.

PubMed

Hammer, Mark M; Raptis, Demetrios A; Cummings, Kristopher W; Mellnick, Vincent M; Bhalla, Sanjeev; Schuerer, Douglas J; Raptis, Constantine A

2016-05-01

Blunt cardiac injury (BCI) may manifest as cardiac contusion or, more rarely, as pericardial or myocardial rupture. Computed tomography (CT) is performed in the vast majority of blunt trauma patients, but the imaging features of cardiac contusion are not well described. To evaluate CT findings and associated injuries in patients with clinically diagnosed BCI. We identified 42 patients with blunt cardiac injury from our institution's electronic medical record. Clinical parameters, echocardiography results, and laboratory tests were recorded. Two blinded reviewers analyzed chest CTs performed in these patients for myocardial hypoenhancement and associated injuries. CT findings of severe thoracic trauma are commonly present in patients with severe BCI; 82% of patients with ECG, cardiac enzyme, and echocardiographic evidence of BCI had abnormalities of the heart or pericardium on CT; 73% had anterior rib fractures, and 64% had pulmonary contusions. Sternal fractures were only seen in 36% of such patients. However, myocardial hypoenhancement on CT is poorly sensitive for those patients with cardiac contusion: 0% of right ventricular contusions and 22% of left ventricular contusions seen on echocardiography were identified on CT. CT signs of severe thoracic trauma are frequently present in patients with severe BCI and should be regarded as indirect evidence of potential BCI. Direct CT findings of myocardial contusion, i.e. myocardial hypoenhancement, are poorly sensitive and should not be used as a screening tool. However, some left ventricular contusions can be seen on CT, and these patients could undergo echocardiography or cardiac MRI to evaluate for wall motion abnormalities. Copyright © 2015 Elsevier Ltd. All rights reserved.

Detection of Cardiac Quiescence from B-Mode Echocardiography Using a Correlation-Based Frame-to-Frame Deviation Measure

PubMed Central

Mcclellan, James H.; Ravichandran, Lakshminarayan; Tridandapani, Srini

2013-01-01

Two novel methods for detecting cardiac quiescent phases from B-mode echocardiography using a correlation-based frame-to-frame deviation measure were developed. Accurate knowledge of cardiac quiescence is crucial to the performance of many imaging modalities, including computed tomography coronary angiography (CTCA). Synchronous electrocardiography (ECG) and echocardiography data were obtained from 10 healthy human subjects (four male, six female, 23–45 years) and the interventricular septum (IVS) was observed using the apical four-chamber echocardiographic view. The velocity of the IVS was derived from active contour tracking and verified using tissue Doppler imaging echocardiography methods. In turn, the frame-to-frame deviation methods for identifying quiescence of the IVS were verified using active contour tracking. The timing of the diastolic quiescent phase was found to exhibit both inter- and intra-subject variability, suggesting that the current method of CTCA gating based on the ECG is suboptimal and that gating based on signals derived from cardiac motion are likely more accurate in predicting quiescence for cardiac imaging. Two robust and efficient methods for identifying cardiac quiescent phases from B-mode echocardiographic data were developed and verified. The methods presented in this paper will be used to develop new CTCA gating techniques and quantify the resulting potential improvement in CTCA image quality. PMID:26609501

Towards Robot-Assisted Echocardiographic Monitoring in Catheterization Laboratories : Usability-Centered Manipulator for Transesophageal Echocardiography.

PubMed

Pahl, Christina; Ebelt, Henning; Sayahkarajy, Mostafa; Supriyanto, Eko; Soesanto, Amiliana

2017-08-15

This paper proposes a robotic Transesophageal Echocardiography (TOE) system concept for Catheterization Laboratories. Cardiovascular disease causes one third of all global mortality. TOE is utilized to assess cardiovascular structures and monitor cardiac function during diagnostic procedures and catheter-based structural interventions. However, the operation of TOE underlies various conditions that may cause a negative impact on performance, the health of the cardiac sonographer and patient safety. These factors have been conflated and evince the potential of robot-assisted TOE. Hence, a careful integration of clinical experience and Systems Engineering methods was used to develop a concept and physical model for TOE manipulation. The motion of different actuators of the fabricated motorized system has been tested. It is concluded that the developed medical system, counteracting conflated disadvantages, represents a progressive approach for cardiac healthcare.

Automatic 3D registration of dynamic stress and rest (82)Rb and flurpiridaz F 18 myocardial perfusion PET data for patient motion detection and correction.

PubMed

Woo, Jonghye; Tamarappoo, Balaji; Dey, Damini; Nakazato, Ryo; Le Meunier, Ludovic; Ramesh, Amit; Lazewatsky, Joel; Germano, Guido; Berman, Daniel S; Slomka, Piotr J

2011-11-01

The authors aimed to develop an image-based registration scheme to detect and correct patient motion in stress and rest cardiac positron emission tomography (PET)/CT images. The patient motion correction was of primary interest and the effects of patient motion with the use of flurpiridaz F 18 and (82)Rb were demonstrated. The authors evaluated stress/rest PET myocardial perfusion imaging datasets in 30 patients (60 datasets in total, 21 male and 9 female) using a new perfusion agent (flurpiridaz F 18) (n = 16) and (82)Rb (n = 14), acquired on a Siemens Biograph-64 scanner in list mode. Stress and rest images were reconstructed into 4 ((82)Rb) or 10 (flurpiridaz F 18) dynamic frames (60 s each) using standard reconstruction (2D attenuation weighted ordered subsets expectation maximization). Patient motion correction was achieved by an image-based registration scheme optimizing a cost function using modified normalized cross-correlation that combined global and local features. For comparison, visual scoring of motion was performed on the scale of 0 to 2 (no motion, moderate motion, and large motion) by two experienced observers. The proposed registration technique had a 93% success rate in removing left ventricular motion, as visually assessed. The maximum detected motion extent for stress and rest were 5.2 mm and 4.9 mm for flurpiridaz F 18 perfusion and 3.0 mm and 4.3 mm for (82)Rb perfusion studies, respectively. Motion extent (maximum frame-to-frame displacement) obtained for stress and rest were (2.2 ± 1.1, 1.4 ± 0.7, 1.9 ± 1.3) mm and (2.0 ± 1.1, 1.2 ±0 .9, 1.9 ± 0.9) mm for flurpiridaz F 18 perfusion studies and (1.9 ± 0.7, 0.7 ± 0.6, 1.3 ± 0.6) mm and (2.0 ± 0.9, 0.6 ± 0.4, 1.2 ± 1.2) mm for (82)Rb perfusion studies, respectively. A visually detectable patient motion threshold was established to be ≥2.2 mm, corresponding to visual user scores of 1 and 2. After motion correction, the average increases in contrast-to-noise ratio (CNR) from all frames for larger than the motion threshold were 16.2% in stress flurpiridaz F 18 and 12.2% in rest flurpiridaz F 18 studies. The average increases in CNR were 4.6% in stress (82)Rb studies and 4.3% in rest (82)Rb studies. Fully automatic motion correction of dynamic PET frames can be performed accurately, potentially allowing improved image quantification of cardiac PET data.

Association of segmental wall motion abnormalities occurring during hemodialysis with post-dialysis fatigue.

PubMed

Dubin, Ruth F; Teerlink, John R; Schiller, Nelson B; Alokozai, Dean; Peralta, Carmen A; Johansen, Kirsten L

2013-10-01

Post-dialysis fatigue (PDF) is a common, debilitating symptom that remains poorly understood. Cardiac wall motion abnormalities (WMAs) may worsen during dialysis, but it is unknown whether WMA are associated with PDF. Forty patients were recruited from University of California San Francisco-affiliated dialysis units between January 2010 and February 2011. Participants underwent echocardiograms before and during the last hour of 79 dialysis sessions. Myocardial segments were graded 1-4 by a blinded reviewer, with four representing the worst WMA, and the segmental scores were summed for each echocardiogram. Patients completed questionnaires about their symptoms. Severe PDF (defined as lasting >2 h after dialysis) was analysed using a generalized linear model with candidate predictors including anemia, intradialytic hemodynamics and cardiac function. Forty-four percent of patients with worsened WMA (n=9) had severe PDF, compared with 13% of patients with improved or unchanged WMA (P = 0.04). A one-point increase in the WMA score during dialysis was associated with a 10% higher RR of severe PDF [RR: 1.1, 95% CI (1.1, 1.2), P < 0.001]. After multivariable adjustment, every point increase in the WMA score was associated with a 2-fold higher risk of severe PDF [RR: 1.9, 95% CI (1.4, 2.6), P < 0.001]. History of depression was associated with severe PDF after adjustment for demographics and comorbidities [RR: 3.4, 95% CI (1.3, 9), P = 0.01], but anemia, hemodynamics and other parameters of cardiac function were not. Although cross-sectional, these results suggest that some patients may experience severe PDF as a symptom of cardiac ischemia occurring during dialysis.

Context indexing of digital cardiac ultrasound records in PACS

NASA Astrophysics Data System (ADS)

Lobodzinski, S. Suave; Meszaros, Georg N.

1998-07-01

Recent wide adoption of the DICOM 3.0 standard by ultrasound equipment vendors created a need for practical clinical implementations of cardiac imaging study visualization, management and archiving, DICOM 3.0 defines only a logical and physical format for exchanging image data (still images, video, patient and study demographics). All DICOM compliant imaging studies must presently be archived on a 650 Mb recordable compact disk. This is a severe limitation for ultrasound applications where studies of 3 to 10 minutes long are a common practice. In addition, DICOM digital echocardiography objects require physiological signal indexing, content segmentation and characterization. Since DICOM 3.0 is an interchange standard only, it does not define how to database composite video objects. The goal of this research was therefore to address the issues of efficient storage, retrieval and management of DICOM compliant cardiac video studies in a distributed PACS environment. Our Web based implementation has the advantage of accommodating both DICOM defined entity-relation modules (equipment data, patient data, video format, etc.) in standard relational database tables and digital indexed video with its attributes in an object relational database. Object relational data model facilitates content indexing of full motion cardiac imaging studies through bi-directional hyperlink generation that tie searchable video attributes and related objects to individual video frames in the temporal domain. Benefits realized from use of bi-directionally hyperlinked data models in an object relational database include: (1) real time video indexing during image acquisition, (2) random access and frame accurate instant playback of previously recorded full motion imaging data, and (3) time savings from faster and more accurate access to data through multiple navigation mechanisms such as multidimensional queries on an index, queries on a hyperlink attribute, free search and browsing.

Accelerated dynamic cardiac MRI exploiting sparse-Kalman-smoother self-calibration and reconstruction (k  -  t SPARKS)

NASA Astrophysics Data System (ADS)

Park, Suhyung; Park, Jaeseok

2015-05-01

Accelerated dynamic MRI, which exploits spatiotemporal redundancies in k  -  t space and coil dimension, has been widely used to reduce the number of signal encoding and thus increase imaging efficiency with minimal loss of image quality. Nonetheless, particularly in cardiac MRI it still suffers from artifacts and amplified noise in the presence of time-drifting coil sensitivity due to relative motion between coil and subject (e.g. free breathing). Furthermore, a substantial number of additional calibrating signals is to be acquired to warrant accurate calibration of coil sensitivity. In this work, we propose a novel, accelerated dynamic cardiac MRI with sparse-Kalman-smoother self-calibration and reconstruction (k  -  t SPARKS), which is robust to time-varying coil sensitivity even with a small number of calibrating signals. The proposed k  -  t SPARKS incorporates Kalman-smoother self-calibration in k  -  t space and sparse signal recovery in x  -   f space into a single optimization problem, leading to iterative, joint estimation of time-varying convolution kernels and missing signals in k  -  t space. In the Kalman-smoother calibration, motion-induced uncertainties over the entire time frames were included in modeling state transition while a coil-dependent noise statistic in describing measurement process. The sparse signal recovery iteratively alternates with the self-calibration to tackle the ill-conditioning problem potentially resulting from insufficient calibrating signals. Simulations and experiments were performed using both the proposed and conventional methods for comparison, revealing that the proposed k  -  t SPARKS yields higher signal-to-error ratio and superior temporal fidelity in both breath-hold and free-breathing cardiac applications over all reduction factors.

Accelerated dynamic cardiac MRI exploiting sparse-Kalman-smoother self-calibration and reconstruction (k  -  t SPARKS).

PubMed

Park, Suhyung; Park, Jaeseok

2015-05-07

Accelerated dynamic MRI, which exploits spatiotemporal redundancies in k  -  t space and coil dimension, has been widely used to reduce the number of signal encoding and thus increase imaging efficiency with minimal loss of image quality. Nonetheless, particularly in cardiac MRI it still suffers from artifacts and amplified noise in the presence of time-drifting coil sensitivity due to relative motion between coil and subject (e.g. free breathing). Furthermore, a substantial number of additional calibrating signals is to be acquired to warrant accurate calibration of coil sensitivity. In this work, we propose a novel, accelerated dynamic cardiac MRI with sparse-Kalman-smoother self-calibration and reconstruction (k  -  t SPARKS), which is robust to time-varying coil sensitivity even with a small number of calibrating signals. The proposed k  -  t SPARKS incorporates Kalman-smoother self-calibration in k  -  t space and sparse signal recovery in x  -   f space into a single optimization problem, leading to iterative, joint estimation of time-varying convolution kernels and missing signals in k  -  t space. In the Kalman-smoother calibration, motion-induced uncertainties over the entire time frames were included in modeling state transition while a coil-dependent noise statistic in describing measurement process. The sparse signal recovery iteratively alternates with the self-calibration to tackle the ill-conditioning problem potentially resulting from insufficient calibrating signals. Simulations and experiments were performed using both the proposed and conventional methods for comparison, revealing that the proposed k  -  t SPARKS yields higher signal-to-error ratio and superior temporal fidelity in both breath-hold and free-breathing cardiac applications over all reduction factors.

Respiratory-phase domain analysis of heart rate variability can accurately estimate cardiac vagal activity during a mental arithmetic task.

PubMed

Kotani, Kiyoshi; Takamasu, Kiyoshi; Tachibana, Makoto

2007-01-01

The objectives of this paper were to present a method to extract the amplitude of RSA in the respiratory-phase domain, to compare that with subjective or objective indices of the MWL (mental workload), and to compare that with a conventional frequency analysis in terms of its accuracy during a mental arithmetic task. HRV (heart rate variability), ILV (instantaneous lung volume), and motion of the throat were measured under a mental arithmetic experiment and subjective and objective indices were also obtained. The amplitude of RSA was extracted in the respiratory-phase domain, and its correlation with the load level was compared with the results of the frequency domain analysis, which is the standard analysis of the HRV. The subjective and objective indices decreased as the load level increased, showing that the experimental protocol was appropriate. Then, the amplitude of RSA in the respiratory-phase domain also decreased with the increase in the load level. The results of the correlation analysis showed that the respiratory-phase domain analysis has higher negative correlations, -0.84 and -0.82, with the load level as determined by simple correlation and rank correlation, respectively, than does frequency analysis, for which the correlations were found to be -0.54 and -0.63, respectively. In addition, it was demonstrated that the proposed method could be applied to the short-term extraction of RSA amplitude. We proposed a simple and effective method to extract the amplitude of the respiratory sinus arrhythmia (RSA) in the respiratory-phase domain and the results show that this method can estimate cardiac vagal activity more accurately than frequency analysis.

Image-Guided Radiotherapy for Left-Sided Breast Cancer Patients: Geometrical Uncertainty of the Heart

DOE Office of Scientific and Technical Information (OSTI.GOV)

Topolnjak, Rajko; Borst, Gerben R.; Nijkamp, Jasper

Purpose: To quantify the geometrical uncertainties for the heart during radiotherapy treatment of left-sided breast cancer patients and to determine and validate planning organ at risk volume (PRV) margins. Methods and Materials: Twenty-two patients treated in supine position in 28 fractions with regularly acquired cone-beam computed tomography (CBCT) scans for offline setup correction were included. Retrospectively, the CBCT scans were reconstructed into 10-phase respiration correlated four-dimensional scans. The heart was registered in each breathing phase to the planning CT scan to establish the respiratory heart motion during the CBCT scan ({sigma}{sub resp}). The average of the respiratory motion was calculatedmore » as the heart displacement error for a fraction. Subsequently, the systematic ({Sigma}), random ({sigma}), and total random ({sigma}{sub tot}={radical}({sigma}{sup 2}+{sigma}{sub resp}{sup 2})) errors of the heart position were calculated. Based on the errors a PRV margin for the heart was calculated to ensure that the maximum heart dose (D{sub max}) is not underestimated in at least 90% of the cases (M{sub heart} = 1.3{Sigma}-0.5{sigma}{sub tot}). All analysis were performed in left-right (LR), craniocaudal (CC), and anteroposterior (AP) directions with respect to both online and offline bony anatomy setup corrections. The PRV margin was validated by accumulating the dose to the heart based on the heart registrations and comparing the planned PRV D{sub max} to the accumulated heart D{sub max}. Results: For online setup correction, the cardiac geometrical uncertainties and PRV margins were N-Ary-Summation = 2.2/3.2/2.1 mm, {sigma} = 2.1/2.9/1.4 mm, and M{sub heart} = 1.6/2.3/1.3 mm for LR/CC/AP, respectively. For offline setup correction these were N-Ary-Summation = 2.4/3.7/2.2 mm, {sigma} = 2.9/4.1/2.7 mm, and M{sub heart} = 1.6/2.1/1.4 mm. Cardiac motion induced by breathing was {sigma}{sub resp} = 1.4/2.9/1.4 mm for LR/CC/AP. The PRV D{sub max} underestimated the accumulated heart D{sub max} for 9.1% patients using online and 13.6% patients using offline bony anatomy setup correction, which validated that PRV margin size was adequate. Conclusion: Considerable cardiac position variability relative to the bony anatomy was observed in breast cancer patients. A PRV margin can be used during treatment planning to take these uncertainties into account.« less

Physiological motion modeling for organ-mounted robots.

PubMed

Wood, Nathan A; Schwartzman, David; Zenati, Marco A; Riviere, Cameron N

2017-12-01

Organ-mounted robots passively compensate heartbeat and respiratory motion. In model-guided procedures, this motion can be a significant source of information that can be used to aid in localization or to add dynamic information to static preoperative maps. Models for estimating periodic motion are proposed for both position and orientation. These models are then tested on animal data and optimal orders are identified. Finally, methods for online identification are demonstrated. Models using exponential coordinates and Euler-angle parameterizations are as accurate as models using quaternion representations, yet require a quarter fewer parameters. Models which incorporate more than four cardiac or three respiration harmonics are no more accurate. Finally, online methods estimate model parameters as accurately as offline methods within three respiration cycles. These methods provide a complete framework for accurately modelling the periodic deformation of points anywhere on the surface of the heart in a closed chest. Copyright © 2017 John Wiley & Sons, Ltd.

Strategies and methodologies to develop techniques for computer-assisted analysis of gas phase formation during altitude decompression

NASA Technical Reports Server (NTRS)

Powell, Michael R.; Hall, W. A.

1993-01-01

It would be of operational significance if one possessed a device that would indicate the presence of gas phase formation in the body during hypobaric decompression. Automated analysis of Doppler gas bubble signals has been attempted for 2 decades but with generally unfavorable results, except with surgically implanted transducers. Recently, efforts have intensified with the introduction of low-cost computer programs. Current NASA work is directed towards the development of a computer-assisted method specifically targeted to EVA, and we are most interested in Spencer Grade 4. We note that Spencer Doppler Grades 1 to 3 have increased in the FFT sonogram and spectrogram in the amplitude domain, and the frequency domain is sometimes increased over that created by the normal blood flow envelope. The amplitude perturbations are of very short duration, in both systole and diastole and at random temporal positions. Grade 4 is characteristic in the amplitude domain but with modest increases in the FFT sonogram and spectral frequency power from 2K to 4K over all of the cardiac cycle. Heart valve motion appears to characteristic display signals: (1) the demodulated Doppler signal amplitude is considerably above the Doppler-shifted blow flow signal (even Grade 4); and (2) demodulated Doppler frequency shifts are considerably greater (often several kHz) than the upper edge of the blood flow envelope. Knowledge of these facts will aid in the construction of a real-time, computer-assisted discriminator to eliminate cardiac motion artifacts. There could also exist perturbations in the following: (1) modifications of the pattern of blood flow in accordance with Poiseuille's Law, (2) flow changes with a change in the Reynolds number, (3) an increase in the pulsatility index, and/or (4) diminished diastolic flow or 'runoff.' Doppler ultrasound devices have been constructed with a three-transducer array and a pulsed frequency generator.

Dynamic positional fate map of the primary heart-forming region.

PubMed

Cui, Cheng; Cheuvront, Tracey J; Lansford, Rusty D; Moreno-Rodriguez, Ricardo A; Schultheiss, Thomas M; Rongish, Brenda J

2009-08-15

Here we show the temporal-spatial orchestration of early heart morphogenesis at cellular level resolution, in vivo, and reconcile conflicting positional fate mapping data regarding the primary heart-forming field(s). We determined the positional fates of precardiac cells using a precision electroporation approach in combination with wide-field time-lapse microscopy in the quail embryo, a warm-blooded vertebrate (HH Stages 4 through 10). Contrary to previous studies, the results demonstrate the existence of a "continuous" circle-shaped heart field that spans the midline, appearing at HH Stage 4, which then expands to form a wide arc of progenitors at HH Stages 5-7. Our time-resolved image data show that a subset of these cardiac progenitor cells do not overlap with the expression of common cardiogenic factors, Nkx-2.5 and Bmp-2, until HH Stage 10, when a tubular heart has formed, calling into question when cardiac fate is specified and by which key factors. Sub-groups and anatomical bands (cohorts) of heart precursor cells dramatically change their relative positions in a process largely driven by endodermal folding and other large-scale tissue deformations. Thus, our novel dynamic positional fate maps resolve the origin of cardiac progenitor cells in amniotes. The data also establish the concept that tissue motion contributes significantly to cellular position fate - i.e., much of the cellular displacement that occurs during assembly of a midline heart tube (HH Stage 9) is NOT due to "migration" (autonomous motility), a commonly held belief. Computational analysis of our time-resolved data lays the foundation for more precise analyses of how cardiac gene regulatory networks correlate with early heart tissue morphogenesis in birds and mammals.

Association of Low-Grade Albuminuria with Adverse Cardiac Mechanics: Findings from the HyperGEN Study

PubMed Central

Katz, Daniel H.; Selvaraj, Senthil; Aguilar, Frank G.; Martinez, Eva E.; Beussink, Lauren; Kim, Kwang-Youn A.; Peng, Jie; Sha, Jin; Irvin, Marguerite R.; Eckfeldt, John H.; Turner, Stephen T.; Freedman, Barry I.; Arnett, Donna K.; Shah, Sanjiv J.

2013-01-01

Introduction Albuminuria is a marker of endothelial dysfunction and has been associated with adverse cardiovascular outcomes. The reasons for this association are unclear, but may be due to the relationship between endothelial dysfunction and intrinsic myocardial dysfunction. Methods and Results In the HyperGEN study, a population- and family-based study of hypertension, we examined the relationship between urine albumin-to-creatinine ratio (UACR) and cardiac mechanics (N=1894, all of whom had normal left ventricular ejection fraction and wall motion). We performed speckle-tracking echocardiographic analysis to quantify global longitudinal, circumferential, and radial strain (GLS, GCS, and GRS, respectively), and early diastolic (e′) tissue velocities. We used E/e′ ratio as a marker of increased LV filling pressures. We used multivariable-adjusted linear mixed effect models to determine independent associations between UACR and cardiac mechanics. The mean age was 50±14 years, 59% were female, and 46% were African-American. Comorbidities were increasingly prevalent among higher UACR quartiles. Albuminuria was associated with GLS, GCS, GRS, e′ velocity, and E/e′ ratio on unadjusted analyses. After adjustment for covariates, UACR was independently associated with lower absolute GLS (multivariable-adjusted mean GLS [95% CI] for UACR Quartile 1 = 15.3 [15.0–15.5]% vs. UACR Q4 = 14.6 [14.3–14.9]%, P for trend <0.001) and increased E/e′ ratio (Q1 = 25.3 [23.5–27.1] vs. Q4 = 29.0 [27.0–31.0], P= 0.003). The association between UACR and GLS was present even in participants with UACR < 30 mg/g (P<0.001 after multivariable adjustment). Conclusions Albuminuria, even at low levels, is associated with adverse cardiac mechanics and higher E/e′ ratio. PMID:24077169

Iterative motion compensation approach for ultrasonic thermal imaging

NASA Astrophysics Data System (ADS)

Fleming, Ioana; Hager, Gregory; Guo, Xiaoyu; Kang, Hyun Jae; Boctor, Emad

2015-03-01

As thermal imaging attempts to estimate very small tissue motion (on the order of tens of microns), it can be negatively influenced by signal decorrelation. Patient's breathing and cardiac cycle generate shifts in the RF signal patterns. Other sources of movement could be found outside the patient's body, like transducer slippage or small vibrations due to environment factors like electronic noise. Here, we build upon a robust displacement estimation method for ultrasound elastography and we investigate an iterative motion compensation algorithm, which can detect and remove non-heat induced tissue motion at every step of the ablation procedure. The validation experiments are performed on laboratory induced ablation lesions in ex-vivo tissue. The ultrasound probe is either held by the operator's hand or supported by a robotic arm. We demonstrate the ability to detect and remove non-heat induced tissue motion in both settings. We show that removing extraneous motion helps unmask the effects of heating. Our strain estimation curves closely mirror the temperature changes within the tissue. While previous results in the area of motion compensation were reported for experiments lasting less than 10 seconds, our algorithm was tested on experiments that lasted close to 20 minutes.

Evaluation of pleural and pericardial effusions by magnetic resonance imaging.

PubMed

Tscholakoff, D; Sechtem, U; de Geer, G; Schmidt, H; Higgins, C B

1987-08-01

MR examinations of 36 patients with pleural and/or pericardial effusions were retrospectively evaluated. The purpose of this study was to determine of MR imaging is capable of differentiating between pleural and pericardial effusions of different compositions using standard electrocardiogram (ECG)-gated and non-gated spin echo pulse sequences. Additional data was obtained from experimental pleural effusions in 10 dogs. The results of this study indicate that old hemorrhages into the pleural or pericardial space can be differentiated from other pleural or pericardial effusions. However, further differentiation between transudates, exudates and sanguinous effusions is not possible on MR images acquired with standard spin echo pulse sequences. Respiratory and cardiac motion are responsible for signal loss, particularly on first echo images. This was documented in experiments in dogs with induced effusions of known composition; "negative" T2 values consistent with fluid motion during imaging sequences were observed in 80% of cases. However, postmortem studies of the dogs with experimental effusions showed differences between effusions with low protein concentrations and higher protein concentrations. We conclude from our study that characterization of pleural and pericardial effusions on standard ECG-gated and non-gated MR examinations is limited to the positive identification of hemorrhage. Motion of the fluid due to cardiac and respiratory activity causes artifactual and unpredictable changes in intensity values negating the more subtle differences in intensity associated with increasing protein content.

Cardiac magnetic resonance imaging in heart failure: where the alphabet begins!

PubMed

Aljizeeri, Ahmed; Sulaiman, Abdulbaset; Alhulaimi, Naji; Alsaileek, Ahmed; Al-Mallah, Mouaz H

2017-07-01

Cardiac Magnetic Resonance Imaging has become a cornerstone in the evaluation of heart failure. It provides a comprehensive evaluation by answering all the pertinent clinical questions across the full pathological spectrum of heart failure. Nowadays, CMR is considered the gold standard in evaluation of ventricular volumes, wall motion and systolic function. Through its unique ability of tissue characterization, it provides incremental diagnostic and prognostic information and thus has emerged as a comprehensive imaging modality in heart failure. This review outlines the role of main conventional CMR sequences in the evaluation of heart failure and their impact in the management and prognosis.

Propofol Induction's Effect on Cardiac Function

ClinicalTrials.gov

2015-03-31

This Study Was Focused to Evaluate Feasibility of Doppler Tissue Monitoring During the Induction Anesthesia,; and Evaluate Routine Propofol Induction's Effect on Myocardial Tissue Motion, Using Non-invasive Doppler Tissue and 2D Speckle Tracking Imaging.; This is the First Study, to Our Knowledge, Which Has Evaluated the Possible Impact of Propofol Induction on LV Function.

Free-breathing cardiac MR stress perfusion with real-time slice tracking.

PubMed

Basha, Tamer A; Roujol, Sébastien; Kissinger, Kraig V; Goddu, Beth; Berg, Sophie; Manning, Warren J; Nezafat, Reza

2014-09-01

To develop a free-breathing cardiac MR perfusion sequence with slice tracking for use after physical exercise. We propose to use a leading navigator, placed immediately before each 2D slice acquisition, for tracking the respiratory motion and updating the slice location in real-time. The proposed sequence was used to acquire CMR perfusion datasets in 12 healthy adult subjects and 8 patients. Images were compared with the conventional perfusion (i.e., without slice tracking) results from the same subjects. The location and geometry of the myocardium were quantitatively analyzed, and the perfusion signal curves were calculated from both sequences to show the efficacy of the proposed sequence. The proposed sequence was significantly better compared with the conventional perfusion sequence in terms of qualitative image scores. Changes in the myocardial location and geometry decreased by 50% in the slice tracking sequence. Furthermore, the proposed sequence had signal curves that are smoother and less noisy. The proposed sequence significantly reduces the effect of the respiratory motion on the image acquisition in both rest and stress perfusion scans. Copyright © 2013 Wiley Periodicals, Inc.

Hypovolemia induced systolic anterior motion of the mitral valve in two dogs.

PubMed

Hammes, K; Novo Matos, J; Baron Toaldo, M; Glaus, T

2016-12-01

Systolic anterior (septal) motion of the mitral valve (SAM) is a common secondary phenomenon in hypertrophic cardiomyopathy (HCM) in people and cats. In humans, it is increasingly recognized that SAM may be found in other cardiac and non-cardiac disease states. In small animal cardiology, SAM unassociated with HCM has been described in dogs with mitral valve dysplasia and right ventricular pressure overload. In this report, we describe two cases of dogs where transient SAM was caused by hypovolemia. When SAM was present both dogs showed pseudohypertrophy and tachycardia. Important factors in the genesis of SAM in this scenario are probably hypovolemia induced changes in left ventricular geometry affecting the orientation of the mitral valve apparatus combined with elevated catecholamine levels. SAM associated with increased wall thickness is not pathognomonic of HCM; this observation is of particular clinical importance when extrapolated to species where HCM is highly prevalent, e.g., cats. An echocardiographic diagnosis should always be evaluated together with full clinical assessment of history and physical examination. Copyright © 2016. Published by Elsevier B.V.

Interatrial septal motion as a novel index to predict left atrial pressure.

PubMed

Masai, Kumiko; Kishima, Hideyuki; Takahashi, Satoshi; Ashida, Kenki; Goda, Akiko; Mine, Takanao; Asakura, Masanori; Ishihara, Masaharu; Masuyama, Tohru

2018-01-22

We investigated whether the interatrial septal (IAS) motion of each heartbeat which is observed by transesophageal echocardiography reflects left atrial pressure (LAP) in patients with atrial fibrillation (AF). We studied 100 patients (70 males, age 67 ± 9 years) who underwent catheter ablation for AF. The amplitude of IAS motion was measured using M-mode and averaged for five cardiac cycles. Left and right atrial pressures, the left to right atrial pressure gradient were directly measured during the catheter ablation. In patients with sinus rhythm during measurement, elevated mean LAP, larger maximum left to right atrial pressure gradient, and greater left atrial emptying fraction were associated with IAS motion. The optimal cut-off value of the IAS motion for predicting high LAP (mean LAP > 15 mmHg) was 8.5 mm (sensitivity 100%, specificity 70.1%) in patients with sinus rhythm during pressure measurement. In addition, all patients were divided into 6 groups based on rhythm during measurement and cutoff value of IAS motion. In patients with sinus rhythm during measurement, low IAS motion group had a highest prevalence of elevated LAP compared with high IAS motion group (64 vs. 0%, P < 0.0001). The amplitude of interatrial septal motion during sinus rhythm reflects left atrial pressure in patients with atrial fibrillation. Interatrial septal motion could be a new index to predict elevated left atrial pressure.

Simple motion correction strategy reduces respiratory-induced motion artifacts for k-t accelerated and compressed-sensing cardiovascular magnetic resonance perfusion imaging.

PubMed

Zhou, Ruixi; Huang, Wei; Yang, Yang; Chen, Xiao; Weller, Daniel S; Kramer, Christopher M; Kozerke, Sebastian; Salerno, Michael

2018-02-01

Cardiovascular magnetic resonance (CMR) stress perfusion imaging provides important diagnostic and prognostic information in coronary artery disease (CAD). Current clinical sequences have limited temporal and/or spatial resolution, and incomplete heart coverage. Techniques such as k-t principal component analysis (PCA) or k-t sparcity and low rank structure (SLR), which rely on the high degree of spatiotemporal correlation in first-pass perfusion data, can significantly accelerate image acquisition mitigating these problems. However, in the presence of respiratory motion, these techniques can suffer from significant degradation of image quality. A number of techniques based on non-rigid registration have been developed. However, to first approximation, breathing motion predominantly results in rigid motion of the heart. To this end, a simple robust motion correction strategy is proposed for k-t accelerated and compressed sensing (CS) perfusion imaging. A simple respiratory motion compensation (MC) strategy for k-t accelerated and compressed-sensing CMR perfusion imaging to selectively correct respiratory motion of the heart was implemented based on linear k-space phase shifts derived from rigid motion registration of a region-of-interest (ROI) encompassing the heart. A variable density Poisson disk acquisition strategy was used to minimize coherent aliasing in the presence of respiratory motion, and images were reconstructed using k-t PCA and k-t SLR with or without motion correction. The strategy was evaluated in a CMR-extended cardiac torso digital (XCAT) phantom and in prospectively acquired first-pass perfusion studies in 12 subjects undergoing clinically ordered CMR studies. Phantom studies were assessed using the Structural Similarity Index (SSIM) and Root Mean Square Error (RMSE). In patient studies, image quality was scored in a blinded fashion by two experienced cardiologists. In the phantom experiments, images reconstructed with the MC strategy had higher SSIM (p < 0.01) and lower RMSE (p < 0.01) in the presence of respiratory motion. For patient studies, the MC strategy improved k-t PCA and k-t SLR reconstruction image quality (p < 0.01). The performance of k-t SLR without motion correction demonstrated improved image quality as compared to k-t PCA in the setting of respiratory motion (p < 0.01), while with motion correction there is a trend of better performance in k-t SLR as compared with motion corrected k-t PCA. Our simple and robust rigid motion compensation strategy greatly reduces motion artifacts and improves image quality for standard k-t PCA and k-t SLR techniques in setting of respiratory motion due to imperfect breath-holding.

[Performance of Thallium 201 rest-redistribution spect to predict viability in recent myocardial infarction].

PubMed

Coll, Claudia; González, Patricio; Massardo, Teresa; Sierralta, Paulina; Humeres, Pamela; Jofré, Josefina; Yovanovich, Jorge; Aramburú, Ivonne; Brugère, Solange; Chamorro, Hernán; Ramírez, Alfredo; Kunstmann, Sonia; López, Héctor

2002-03-01

The detection of viability after acute myocardial infarction is primordial to select the most appropriate therapy, to decrease cardiac events and abnormal remodeling. Thallium201 SPECT is one of the radionuclide techniques used to detect viability. To evaluate the use of Thallium201 rest-redistribution SPECT to detect myocardial viability in reperfused patients after a recent myocardial infarction. Forty one patients with up to of 24 days of evolution of a myocardial infarction were studied. All had angiographically demonstrated coronary artery disease and were subjected to a successful thrombolysis, angioplasty or bypass grafting. SPECT Thallium201 images were acquired at rest and after 4 h of redistribution. These results were compared with variations in wall motion score, studied at baseline and after 3 or 4 months with echocardiography. The sensitivity of rest-redistribution Thallium201 SPECT, to predict recovery of wall motion was 91% when patient analysis was performed and 79% when segmental analysis was done in the culprit region. The figures for specificity were 56 and 73% respectively. Rest-distribution Thallium201 SPECT has an excellent sensitivity to predict myocardial viability in recent myocardial infarction. The data obtained in this study is similar to that reported for chronic coronary artery disease.

Numerical analysis of the hemodynamic effect of plaque ulceration in the stenotic carotid artery bifurcation

NASA Astrophysics Data System (ADS)

Wong, Emily Y.; Milner, Jaques S.; Steinman, David A.; Poepping, Tamie L.; Holdsworth, David W.

2009-02-01

The presence of ulceration in carotid artery plaque is an independent risk factor for thromboembolic stroke. However, the associated pathophysiological mechanisms - in particular the mechanisms related to the local hemodynamics in the carotid artery bifurcation - are not well understood. We investigated the effect of carotid plaque ulceration on the local time-varying three-dimensional flow field using computational fluid dynamics (CFD) models of a stenosed carotid bifurcation geometry, with and without the presence of ulceration. CFD analysis of each model was performed with a spatial finite element discretization of over 150,000 quadratic tetrahedral elements and a temporal discretization of 4800 timesteps per cardiac cycle, to adequately resolve the flow field and pulsatile flow, respectively. Pulsatile flow simulations were iterated for five cardiac cycles to allow for cycle-to-cycle analysis following the damping of initial transients in the solution. Comparison between models revealed differences in flow patterns induced by flow exiting from the region of the ulcer cavity, in particular, to the shape, orientation and helicity of the high velocity jet through the stenosis. The stenotic jet in both models exhibited oscillatory motion, but produced higher levels of phase-ensembled turbulence intensity in the ulcerated model. In addition, enhanced out-of-plane recirculation and helical flow was observed in the ulcerated model. These preliminary results suggest that local fluid behaviour may contribute to the thrombogenic risk associated with plaque ulcerations in the stenotic carotid artery bifurcation.

Association of apical rocking with super-response to cardiac resynchronisation therapy.

PubMed

Ghani, A; Delnoy, P P H M; Smit, J J J; Ottervanger, J P; Ramdat Misier, A R; Adiyaman, A; Elvan, A

2016-01-01

Super-responders to cardiac resynchronisation therapy (CRT) show an exceptional improvement in left ventricular ejection fraction (LVEF). Previous studies showed that apical rocking was independently associated with echocardiographic response to CRT. However, little is known about the association between apical rocking and super-response to CRT. To determine the independent association of LV apical rocking with super-response to CRT in a large cohort. A cohort of 297 consecutive heart failure patients treated with primary indication for CRT-D were included in an observational registry. Apical rocking was defined as motion of the left ventricular (LV) apical myocardium perpendicular to the LV long axis. 'Super-response' was defined by the top quartile of LVEF response based on change from baseline to follow-up echocardiogram. Best-subset regression analysis identified predictors of LVEF super-response to CRT. Apical rocking was present in 45 % of patients. Super-responders had an absolute mean LVEF increase of 27 % (LVEF 22.0 % ± 5.7 at baseline and 49.0 % ± 7.5 at follow-up). Apical rocking was significantly more common in super-responders compared with non-super-responders (76 and 34 %, P < 0.001). In univariate analysis, female gender (OR 2.39, 95 % CI 1.38-4.11), lower LVEF at baseline (OR 0.91 95 % CI 0.87-0.95), non-ischaemic aetiology (OR 4.15, 95 % CI 2.33-7.39) and apical rocking (OR 6.19, 95 % CI 3.40-11.25) were associated with super-response. In multivariate analysis, apical rocking was still strongly associated with super-response (OR 5.82, 95 % CI 2.68-12.61). Super-responders showed an excellent clinical prognosis with a very low incidence of heart failure admission, cardiac mortality and appropriate ICD therapy. Apical rocking is independently associated with super-response to CRT.

Right ventricular longitudinal strain correlates well with right ventricular stroke work index in patients with advanced heart failure referred for heart transplantation.

PubMed

Cameli, Matteo; Lisi, Matteo; Righini, Francesca Maria; Tsioulpas, Charilaos; Bernazzali, Sonia; Maccherini, Massimo; Sani, Guido; Ballo, Piercarlo; Galderisi, Maurizio; Mondillo, Sergio

2012-03-01

Right ventricular (RV) systolic function has a critical role in determining the clinical outcome and success of using left ventricular assist devices (LVADs) in patients with refractory heart failure. Tissue Doppler and M-mode measurements of tricuspid systolic motion (tricuspid S' and tricuspid annular plane systolic excursion [TAPSE]) are the most currently used methods for the quantification of RV longitudinal function; RV deformation analysis by speckle-tracking echocardiography (STE) has recently allowed the analysis of global RV longitudinal function. Using cardiac catheterization as the reference standard, this study aimed at exploring the correlation between RV longitudinal function by STE and RV stroke work index (RVSWI) in patients referred for cardiac transplantation. Right-side heart catheterization and transthoracic echo Doppler were simultaneously performed in 41 patients referred for cardiac transplantation evaluation for advanced systolic heart failure. Thermodilution RV stroke volume and invasive pulmonary pressures were used to obtain RVSWI. RV longitudinal strain (RVLS) by STE was assessed averaging all segments in apical 4-chamber view (global RVLS) and by averaging RV free-wall segments (free-wall RVLS). Tricuspid S' and TAPSE were also calculated. No significant correlations were found for TAPSE or tricuspid S' with RVSWI (r = 0.14; r = 0.06; respectively). Close negative correlations between global RVLS and free-wall RVLS with the RVSWI were found (r = -0.75; r = -0.82; respectively; both P < .0001). Furthermore, free-wall RVLS demonstrated the highest diagnostic accuracy (area under the receiver operating characteristic (ROC) curve 0.90) and good sensitivity and specificity of 92% and 86%, respectively, to predict depressed RVSWI using a cutoff value of less than -11.8%. In a group of patients referred for heart transplantation, TAPSE and tricuspid S' did not correlate with invasively obtained RVSWI. RV longitudinal deformation analysis by STE correlated well with RVSWI, providing a better estimation of RV systolic performance. Copyright © 2012 Elsevier Inc. All rights reserved.

Stress echocardiography for the diagnosis of coronary artery disease: an evidence-based analysis.

PubMed

2010-01-01

In July 2009, the Medical Advisory Secretariat (MAS) began work on Non-Invasive Cardiac Imaging Technologies for the Diagnosis of Coronary Artery Disease (CAD), an evidence-based review of the literature surrounding different cardiac imaging modalities to ensure that appropriate technologies are accessed by patients suspected of having CAD. This project came about when the Health Services Branch at the Ministry of Health and Long-Term Care asked MAS to provide an evidentiary platform on effectiveness and cost-effectiveness of non-invasive cardiac imaging modalities.After an initial review of the strategy and consultation with experts, MAS identified five key non-invasive cardiac imaging technologies for the diagnosis of CAD. Evidence-based analyses have been prepared for each of these five imaging modalities: cardiac magnetic resonance imaging, single photon emission computed tomography, 64-slice computed tomographic angiography, stress echocardiography, and stress echocardiography with contrast. For each technology, an economic analysis was also completed (where appropriate). A summary decision analytic model was then developed to encapsulate the data from each of these reports (available on the OHTAC and MAS website).The Non-Invasive Cardiac Imaging Technologies for the Diagnosis of Coronary Artery Disease series is made up of the following reports, which can be publicly accessed at the MAS website at: www.health.gov.on.ca/mas">www.health.gov.on.ca/mas or at www.health.gov.on.ca/english/providers/program/mas/mas_about.htmlSINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY FOR THE DIAGNOSIS OF CORONARY ARTERY DISEASE: An Evidence-Based AnalysisSTRESS ECHOCARDIOGRAPHY FOR THE DIAGNOSIS OF CORONARY ARTERY DISEASE: An Evidence-Based AnalysisSTRESS ECHOCARDIOGRAPHY WITH CONTRAST FOR THE DIAGNOSIS OF CORONARY ARTERY DISEASE: An Evidence-Based Analysis64-Slice Computed Tomographic Angiography for the Diagnosis of Coronary Artery Disease: An Evidence-Based AnalysisCARDIAC MAGNETIC RESONANCE IMAGING FOR THE DIAGNOSIS OF CORONARY ARTERY DISEASE: An Evidence-Based AnalysisPease note that two related evidence-based analyses of non-invasive cardiac imaging technologies for the assessment of myocardial viability are also available on the MAS website:POSITRON EMISSION TOMOGRAPHY FOR THE ASSESSMENT OF MYOCARDIAL VIABILITY: An Evidence-Based AnalysisMAGNETIC RESONANCE IMAGING FOR THE ASSESSMENT OF MYOCARDIAL VIABILITY: an Evidence-Based AnalysisThe Toronto Health Economics and Technology Assessment Collaborative has also produced an associated economic report entitled:The Relative Cost-effectiveness of Five Non-invasive Cardiac Imaging Technologies for Diagnosing Coronary Artery Disease in Ontario [Internet]. Available from: http://theta.utoronto.ca/reports/?id=7 OBJECTIVE: The objective of the analysis is to determine the diagnostic accuracy of stress echocardiography (ECHO) in the diagnosis of patients with suspected coronary artery disease (CAD) compared to coronary angiography (CA). STRESS ECHOCARDIOGRAPHY: Stress ECHO is a non-invasive technology that images the heart using ultrasound. It is one of the most commonly employed imaging techniques for investigating a variety of cardiac abnormalities in both community and hospital settings. A complete ECHO exam includes M-mode, 2-dimensional (2-D) images and Doppler imaging. In order to diagnosis CAD and assess whether myocardial ischemia is present, images obtained at rest are compared to those obtained during or immediately after stress. The most commonly used agents used to induce stress are exercise and pharmacological agents such as dobutamine and dipyridamole. The hallmark of stress-induced myocardial ischemia is worsening of wall motion abnormalities or the development of new wall motion abnormalities. A major challenge for stress ECHO is that the interpretation of wall motion contractility and function is subjective. This leads to inter-observer variability and reduced reproducibility. Further, it is estimated that approximately 30% of patients have sub-optimal stress ECHO exams. To overcome this limitation, contrast agents for LV opacification have been developed. Although stress ECHO is a relatively easy to use technology that poses only a low risk of adverse events compared to other imaging technologies, it may potentially be overused and/or misused in CAD diagnosis. Several recent advances have been made focusing on quantitative methods for assessment, improved image quality and enhanced portability, however, evidence on the effectiveness and clinical utility of these enhancements is limited. EVIDENCE-BASED ANALYSIS: What is the diagnostic accuracy of stress ECHO for the diagnosis of patients with suspected CAD compared to the reference standard of CA?What is the clinical utility() of stress ECHO? A literature search was performed on August 28, 2009 using OVID MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, the Cumulative Index to Nursing & Allied Health Literature (CINAHL), the Cochrane Library, and the International Agency for Health Technology Assessment (INAHTA) for studies published from January 1, 2004 until August 21, 2009. Abstracts were reviewed by a single reviewer and, for those studies meeting the eligibility criteria, full-text articles were obtained. Reference lists were also examined for any relevant studies not identified through the search. Systematic reviews, meta-analyses, randomized controlled trials, prospective observational studies, retrospective analysesMinimum sample size of 20 enrolled patientsComparison to CA (reference standard)Definition of CAD specified as either ≥50%, ≥70% or ≥75% coronary artery stenosis on CAReporting accuracy data on individual patients (rather than accuracy data stratified by segments of the heart)EnglishHuman Duplicate studiesNon-systematic reviews, case reportsGrey literature (e.g., conference abstracts)Insufficient data for independent calculation of sensitivity and specificityUse of ECHO for purposes other than diagnosis of CAD (e.g., arrhythmia, valvular disease, mitral stenosis, pre-operative risk of MI)Transesophageal ECHO since its primary use is for non-CAD indications such as endocarditis, intracardiac thrombi, valvular disordersOnly resting ECHO performed Accuracy outcomes (sensitivity, specificity, positive predictive value, negative predictive value)Costs Given the vast amount of published literature on stress ECHO, it was decided to focus on the studies contained in the comprehensive 2007 review by Heijenbrok-Kal et al. (1) as a basis for the MAS evidence-based analysis. In applying our inclusion and exclusion criteria, 105 observational studies containing information on 13,035 patients were included. Six studies examined stress ECHO with adenosine, 26 with dipyridamole and 77 with dobutamine, the latter being the most commonly used pharmacological stress ECHO agent in Ontario. A further 18 studies employed exercise as the stressor.() The prevalence of CAD ranged from 19% to 94% with a mean estimated prevalence of 70%. Based on the results of these studies the following conclusions were made: Based on the available evidence, stress ECHO is a useful imaging modality for the diagnosis of CAD in patients with suspected disease. The overall pooled sensitivity is 0.80 (95% CI: 0.77 - 0.82) and the pooled specificity is 0.84 (95% CI: 0.82 - 0.87) using CA as the reference standard. The AUC derived from the sROC curve is 0.895 and the DOR is 20.64.For pharmacological stress, the pooled sensitivity is 0.79 (95% CI: 0.71 - 0.87) and the pooled specificity is 0.85 (95% CI: 0.83 - 0.88). When exercise is employed as the stress agent, the pooled sensitivity is 0.81 (95% CI: 0.76- 0.86) and the pooled specificity is 0.79 (95% CI: 0.71 - 0.87). Although pharmacological stress and exercise stress would be indicated for different patient populations based on ability to exercise there were no significant differences in sensitivity and specificity.Based on clinical experts, diagnostic accuracy on stress ECHO depends on the patient population, the expertise of the interpreter and the quality of the image.

Cardiovascular applications of magnetic resonance imaging

PubMed Central

Pflugfelder, Peter W.; Wisenberg, Gerald; Prato, Frank S.

1985-01-01

Magnetic resonance (MR) imaging is a unique imaging modality that is gaining rapid acceptance for a variety of medical indications. Diagnostic information is obtained noninvasively, without the potential hazards of ionizing radiation. The spatial resolution and anatomic detail of MR imaging rival those of other currently available imaging methods. By gating to an electrocardiographic signal cardiac imaging is possible. Since March 1983 the authors have had experience with cardiac MR imaging in both animals and humans. Cardiac anatomy is well shown by this technique, which allows detection and characterization of intracardiac masses, congenital heart disease and anomalies of the great vessels. Myocardial infarction has been detected in both animals and humans without the use of contrast agents, and acute cardiac transplant rejection has been visualized in an animal model. Limitations of MR imaging primarily have been lengthy imaging times and the sensitivity of the images to motion. With further investigation and experience this technique may become useful for studying a wide variety of cardiovascular disorders. ImagesFig. 2Fig. 3Fig. 4Fig. 5Fig. 6 PMID:3904969

[Influence of detomidine on echocardiographic function parameters and cardiac hemodynamics in horses with and without heart murmur].

PubMed

Gehlen, H; Kroker, K; Deegen, E; Stadler, P

2004-03-01

30 warmblood horses were examined before and after sedation with 20 micrograms/kg BW detomidine, to determine changes of cardiac function parameters, using B-mode, M-mode and Doppler echocardiography. 15 horses showed a heart murmur, but no clinical signs of cardiac heart failure, 15 horses had neither a heart murmur nor other signs of cardiac disease. After sedation with detomidine we could recognise a significant increase of end-diastolic left atrium diameter, an increase of end-systolic left ventricular diameter and aortic root diameter. The end-systolic thickness of papillary muscle and interventricular septum showed a decrease. Fractional shortening and amplitude of left ventricular wall motion was decreased after sedation. The mitral valve echogram revealed a presystolic valve closure and an inflection in the Ac slope (B-notch) in xy horses before sedation. Both increased after sedation with detomidine. Doppler echocardiography showed a decrease of blood flow velocity and velocity time integral (VTI) in the left and right ventricular outflow tract after sedation. Regurgitant flow signals were intensified following sedation in xy horses, especially at the mitral valve.

Three-dimensional ballistocardiography in microgravity: a review of past research.

PubMed

De Ridder, S; Migeotte, P-F; Neyt, X; Pattyn, N; Prisk, G K

2011-01-01

This paper gives a short review of research on ballistocardiography in microgravity and indicates the benefits from this research for the use of BCG as a terrestrial cardiac monitoring system. In the past, 3-D methods required large devices to decouple the subject from the terrestrial environment and hence, BCG on Earth is usually limited to unidirectional recordings of the motion in the head-to-foot direction. However, microgravity provides a suspension-free environment where accelerations can be measured in all directions without the influence of gravity. Microgravity research indicated that along with the acceleration in the head-to-foot direction, the accelerations in the lateral and dorso-ventral direction are important in understanding the physiological forces during a cardiac cycle. Further, lung volume has a large influence on the transmission of cardiac forces to the surface of the body. To date, only the three separate components of the acceleration vector have been analyzed in 3-D BCG studies. Using the true acceleration and displacement vector (orientation and magnitude), rather than the three separate components, may permit more accurate cardiac event detection.

A comprehensive gene expression analysis at sequential stages of in vitro cardiac differentiation from isolated MESP1-expressing-mesoderm progenitors

PubMed Central

den Hartogh, Sabine C.; Wolstencroft, Katherine; Mummery, Christine L.; Passier, Robert

2016-01-01

In vitro cardiac differentiation of human pluripotent stem cells (hPSCs) closely recapitulates in vivo embryonic heart development, and therefore, provides an excellent model to study human cardiac development. We recently generated the dual cardiac fluorescent reporter MESP1mCherry/wNKX2-5eGFP/w line in human embryonic stem cells (hESCs), allowing the visualization of pre-cardiac MESP1+ mesoderm and their further commitment towards the cardiac lineage, marked by activation of the cardiac transcription factor NKX2-5. Here, we performed a comprehensive whole genome based transcriptome analysis of MESP1-mCherry derived cardiac-committed cells. In addition to previously described cardiac-inducing signalling pathways, we identified novel transcriptional and signalling networks indicated by transient activation and interactive network analysis. Furthermore, we found a highly dynamic regulation of extracellular matrix components, suggesting the importance to create a versatile niche, adjusting to various stages of cardiac differentiation. Finally, we identified cell surface markers for cardiac progenitors, such as the Leucine-rich repeat-containing G-protein coupled receptor 4 (LGR4), belonging to the same subfamily of LGR5, and LGR6, established tissue/cancer stem cells markers. We provide a comprehensive gene expression analysis of cardiac derivatives from pre-cardiac MESP1-progenitors that will contribute to a better understanding of the key regulators, pathways and markers involved in human cardiac differentiation and development. PMID:26783251

Compressed sensing reconstruction of cardiac cine MRI using golden angle spiral trajectories

NASA Astrophysics Data System (ADS)

Tolouee, Azar; Alirezaie, Javad; Babyn, Paul

2015-11-01

In dynamic cardiac cine Magnetic Resonance Imaging (MRI), the spatiotemporal resolution is limited by the low imaging speed. Compressed sensing (CS) theory has been applied to improve the imaging speed and thus the spatiotemporal resolution. The purpose of this paper is to improve CS reconstruction of under sampled data by exploiting spatiotemporal sparsity and efficient spiral trajectories. We extend k-t sparse algorithm to spiral trajectories to achieve high spatio temporal resolutions in cardiac cine imaging. We have exploited spatiotemporal sparsity of cardiac cine MRI by applying a 2D + time wavelet-Fourier transform. For efficient coverage of k-space, we have used a modified version of multi shot (interleaved) spirals trajectories. In order to reduce incoherent aliasing artifact, we use different random undersampling pattern for each temporal frame. Finally, we have used nonuniform fast Fourier transform (NUFFT) algorithm to reconstruct the image from the non-uniformly acquired samples. The proposed approach was tested in simulated and cardiac cine MRI data. Results show that higher acceleration factors with improved image quality can be obtained with the proposed approach in comparison to the existing state-of-the-art method. The flexibility of the introduced method should allow it to be used not only for the challenging case of cardiac imaging, but also for other patient motion where the patient moves or breathes during acquisition.

Ultrafast Ultrasound Imaging of Ocular Anatomy and Blood Flow

PubMed Central

Urs, Raksha; Ketterling, Jeffrey A.; Silverman, Ronald H.

2016-01-01

Purpose Ophthalmic ultrasound imaging is currently performed with mechanically scanned single-element probes. These probes have limited capabilities overall and lack the ability to image blood flow. Linear-array systems are able to detect blood flow, but these systems exceed ophthalmic acoustic intensity safety guidelines. Our aim was to implement and evaluate a new linear-array–based technology, compound coherent plane-wave ultrasound, which offers ultrafast imaging and depiction of blood flow at safe acoustic intensity levels. Methods We compared acoustic intensity generated by a 128-element, 18-MHz linear array operated in conventionally focused and plane-wave modes and characterized signal-to-noise ratio (SNR) and lateral resolution. We developed plane-wave B-mode, real-time color-flow, and high-resolution depiction of slow flow in postprocessed data collected continuously at a rate of 20,000 frames/s. We acquired in vivo images of the posterior pole of the eye by compounding plane-wave images acquired over ±10° and produced images depicting orbital and choroidal blood flow. Results With the array operated conventionally, Doppler modes exceeded Food and Drug Administration safety guidelines, but plane-wave modalities were well within guidelines. Plane-wave data allowed generation of high-quality compound B-mode images, with SNR increasing with the number of compounded frames. Real-time color-flow Doppler readily visualized orbital blood flow. Postprocessing of continuously acquired data blocks of 1.6-second duration allowed high-resolution depiction of orbital and choroidal flow over the cardiac cycle. Conclusions Newly developed high-frequency linear arrays in combination with plane-wave techniques present opportunities for the evaluation of ocular anatomy and blood flow, as well as visualization and analysis of other transient phenomena such as vessel wall motion over the cardiac cycle and saccade-induced vitreous motion. PMID:27428169

Right Ventricular Strain, Torsion, and Dyssynchrony in Healthy Subjects using 3D Spiral Cine DENSE Magnetic Resonance Imaging

PubMed Central

Suever, Jonathan D; Wehner, Gregory J; Jing, Linyuan; Powell, David K; Hamlet, Sean M; Grabau, Jonathan D; Mojsejenko, Dimitri; Andres, Kristin N; Haggerty, Christopher M; Fornwalt, Brandon K

2017-01-01

Mechanics of the left ventricle (LV) are important indicators of cardiac function. The role of right ventricular (RV) mechanics is largely unknown due to the technical limitations of imaging its thin wall and complex geometry and motion. By combining 3D Displacement Encoding with Stimulated Echoes (DENSE) with a post-processing pipeline that includes a local coordinate system, it is possible to quantify RV strain, torsion, and synchrony. In this study, we sought to characterize RV mechanics in 50 healthy individuals and compare these values to their LV counterparts. For each cardiac frame, 3D displacements were fit to continuous and differentiable radial basis functions, allowing for the computation of the 3D Cartesian Lagrangian strain tensor at any myocardial point. The geometry of the RV was extracted via a surface fit to manually delineated endocardial contours. Throughout the RV, a local coordinate system was used to transform from a Cartesian strain tensor to a polar strain tensor. It was then possible to compute peak RV torsion as well as peak longitudinal and circumferential strain. A comparable analysis was performed for the LV. Dyssynchrony was computed from the standard deviation of regional activation times. Global circumferential strain was comparable between the RV and LV (−18.0% for both) while longitudinal strain was greater in the RV (−18.1% vs. −15.7%). RV torsion was comparable to LV torsion (6.2 vs. 7.1 degrees, respectively). Regional activation times indicated that the RV contracted later but more synchronously than the LV. 3D spiral cine DENSE combined with a post–processing pipeline that includes a local coordinate system can resolve both the complex geometry and 3D motion of the RV. PMID:28055859

Speckle variance optical coherence tomography of blood flow in the beating mouse embryonic heart.

PubMed

Grishina, Olga A; Wang, Shang; Larina, Irina V

2017-05-01

Efficient separation of blood and cardiac wall in the beating embryonic heart is essential and critical for experiment-based computational modelling and analysis of early-stage cardiac biomechanics. Although speckle variance optical coherence tomography (SV-OCT) relying on calculation of intensity variance over consecutively acquired frames is a powerful approach for segmentation of fluid flow from static tissue, application of this method in the beating embryonic heart remains challenging because moving structures generate SV signal indistinguishable from the blood. Here, we demonstrate a modified four-dimensional SV-OCT approach that effectively separates the blood flow from the dynamic heart wall in the beating mouse embryonic heart. The method takes advantage of the periodic motion of the cardiac wall and is based on calculation of the SV signal over the frames corresponding to the same phase of the heartbeat cycle. Through comparison with Doppler OCT imaging, we validate this speckle-based approach and show advantages in its insensitiveness to the flow direction and velocity as well as reduced influence from the heart wall movement. This approach has a potential in variety of applications relying on visualization and segmentation of blood flow in periodically moving structures, such as mechanical simulation studies and finite element modelling. Picture: Four-dimensional speckle variance OCT imaging shows the blood flow inside the beating heart of an E8.5 mouse embryo. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Smartphone-Based Cardiac Rehabilitation Program: Feasibility Study.

PubMed

Chung, Heewon; Ko, Hoon; Thap, Tharoeun; Jeong, Changwon; Noh, Se-Eung; Yoon, Kwon-Ha; Lee, Jinseok

2016-01-01

We introduce a cardiac rehabilitation program (CRP) that utilizes only a smartphone, with no external devices. As an efficient guide for cardiac rehabilitation exercise, we developed an application to automatically indicate the exercise intensity by comparing the estimated heart rate (HR) with the target heart rate zone (THZ). The HR is estimated using video images of a fingertip taken by the smartphone's built-in camera. The introduced CRP app includes pre-exercise, exercise with intensity guidance, and post-exercise. In the pre-exercise period, information such as THZ, exercise type, exercise stage order, and duration of each stage are set up. In the exercise with intensity guidance, the app estimates HR from the pulse obtained using the smartphone's built-in camera and compares the estimated HR with the THZ. Based on this comparison, the app adjusts the exercise intensity to shift the patient's HR to the THZ during exercise. In the post-exercise period, the app manages the ratio of the estimated HR to the THZ and provides a questionnaire on factors such as chest pain, shortness of breath, and leg pain during exercise, as objective and subjective evaluation indicators. As a key issue, HR estimation upon signal corruption due to motion artifacts is also considered. Through the smartphone-based CRP, we estimated the HR accuracy as mean absolute error and root mean squared error of 6.16 and 4.30bpm, respectively, with signal corruption due to motion artifacts being detected by combining the turning point ratio and kurtosis.

Smartphone-Based Cardiac Rehabilitation Program: Feasibility Study

PubMed Central

Chung, Heewon; Yoon, Kwon-Ha; Lee, Jinseok

2016-01-01

We introduce a cardiac rehabilitation program (CRP) that utilizes only a smartphone, with no external devices. As an efficient guide for cardiac rehabilitation exercise, we developed an application to automatically indicate the exercise intensity by comparing the estimated heart rate (HR) with the target heart rate zone (THZ). The HR is estimated using video images of a fingertip taken by the smartphone’s built-in camera. The introduced CRP app includes pre-exercise, exercise with intensity guidance, and post-exercise. In the pre-exercise period, information such as THZ, exercise type, exercise stage order, and duration of each stage are set up. In the exercise with intensity guidance, the app estimates HR from the pulse obtained using the smartphone’s built-in camera and compares the estimated HR with the THZ. Based on this comparison, the app adjusts the exercise intensity to shift the patient’s HR to the THZ during exercise. In the post-exercise period, the app manages the ratio of the estimated HR to the THZ and provides a questionnaire on factors such as chest pain, shortness of breath, and leg pain during exercise, as objective and subjective evaluation indicators. As a key issue, HR estimation upon signal corruption due to motion artifacts is also considered. Through the smartphone-based CRP, we estimated the HR accuracy as mean absolute error and root mean squared error of 6.16 and 4.30bpm, respectively, with signal corruption due to motion artifacts being detected by combining the turning point ratio and kurtosis. PMID:27551969

Atrial and ventricular function after cardioversion of atrial fibrillation.

PubMed Central

Xiong, C.; Sonnhag, C.; Nylander, E.; Wranne, B.

1995-01-01

OBJECTIVE--Previous studies on atrial recovery after cardioversion of atrial fibrillation have not taken into account new knowledge about the pathophysiology of transmitral and transtricuspid flow velocity patterns. It is possible to shed further light on this problem if atrioventricular inflow velocity, venous filling pattern, and atrioventricular annulus motion are recorded and interpreted together. DESIGN--Prospective examinations of mitral and tricuspid transvalvar flow velocities, superior caval and pulmonary venous filling, and mitral and tricuspid annulus motion were recorded using Doppler echocardiography. Examinations were performed before and 24 hours, 1 month, and 20 months after cardioversion. SETTING--Tertiary referral centre for cardiac disease with facilities for invasive and non-invasive investigation. PATIENTS--16 patients undergoing cardioversion of atrial fibrillation in whom sinus rhythm had persisted for 24 hours or more. RESULTS--Before conversion there was no identifiable A wave in transvalvar flow recordings. The total motion of the tricuspid and mitral annulus was subnormal and there was no identifiable atrial component. Venous flow patterns in general showed a low systolic velocity. After conversion, A waves and atrial components were seen in all patients and increased significantly (P < 0.01) with time. There was a similar time course for the amplitude of annulus atrial components, an increased systolic component of venous inflow, an increased A wave velocity, and a decreased E/A ratio of the transvalvar velocity curves. The ventricular component of annulus motion was unchanged. Changes in general occurred earlier on the right side than the left. CONCLUSIONS--This study indicates that, in addition to the previously known electromechanical dissociation of atrial recovery that exists after cardioversion of atrial fibrillation, there may also be a transient deterioration of ventricular function modulating the transvalvar inflow velocity recordings. Function on the right side generally becomes normal earlier than on the left. Integration of information from transvalvar inflow curves, annulus motion, and venous filling patterns gives additional insight into cardiac function. PMID:7547019

The impact of ergometer design on hip and trunk muscle activity patterns in elite rowers: an electromyographic assessment.

PubMed

Nowicky, Alex V; Horne, Sara; Burdett, Richard

2005-03-01

THIS STUDY USED SURFACE ELECTROMYOGRAPHY (SEMG) TO EXAMINE WHETHER THERE WERE DIFFERENCES IN HIP AND TRUNK MUSCLE ACTIVATION DURING THE ROWING CYCLE ON TWO OF THE MOST WIDELY USED AIR BRAKED ERGOMETERS: the Concept 2C and the Rowperfect. sEMG methods were used to record the muscle activity patterns from the right: m. Erector spinae (ES), m. Rectus Abdominus (RA), m. Rectus Femoris (RF) and m. Biceps Femoris (BF) for their contributions as agonist-antagonist pairs underlying hip and trunk extension/flexion. The sEMG activity patterns of these muscles were examined in six young male elite rowers completing a 2 minute set at a moderate training intensity (23 stroke·min(-1) and 1:47.500 m(-1) split time, 300W). The rowers closely maintained the required target pace through visual inspection of the standard LCD display of each ergometer. The measurements of duration of each rowing cycle and onset of each stroke during the test were recorded simultaneously with the sEMG activity through the additional instrumentation of a foot-pressure switch and handle accelerometry. There were no significant differences between the two ergometer designs in group means for: work rate (i.e., rowing speed and stroke rate), metabolic load as measured by mean heart rate, rowing cycle duration, or timing of the stroke in the cycle. 2-D motion analysis of hip and knee motion for the rowing cycle from the video footage taken during the test also revealed no significant differences in the joint range of motion between the ergometers. Ensemble average sEMG activity profiles based on 30+ strokes were obtained for each participant and normalised per 10% intervals of the cycle duration as well as for peak mean sEMG amplitude for each muscle. A repeated measures ANOVA on the sEMG activity per 10% interval for the four muscles contributing to hip and trunk motion during the rowing cycle revealed no significant differences between the Concept 2C and Rowperfect (F = 0.070, df = 1,5, p = 0.802). The outcome of this study suggests that the two different ergometer designs are equally useful for dry land training. Key PointsThe effects of endurance training on HR recovery after exercise and cardiac ANS modulation were investigated in female marathon runners by comparing with untrained controls.Time and frequency domain analysis of HRV was used to investigate cardiac ANS modulation.As compared with untrained controls, the female marathon runners showed faster HR recovery after exercise, which should result from their higher levels of HRV, higher aerobic capacity and exaggerated blood pressure response to exercise.

The Impact of Ergometer Design on Hip and Trunk Muscle Activity Patterns in Elite Rowers: An Electromyographic Assessment

PubMed Central

Nowicky, Alex V.; Horne, Sara; Burdett, Richard

2005-01-01

This study used surface electromyography (sEMG) to examine whether there were differences in hip and trunk muscle activation during the rowing cycle on two of the most widely used air braked ergometers: the Concept 2C and the Rowperfect. sEMG methods were used to record the muscle activity patterns from the right: m. Erector spinae (ES), m. Rectus Abdominus (RA), m. Rectus Femoris (RF) and m. Biceps Femoris (BF) for their contributions as agonist-antagonist pairs underlying hip and trunk extension/flexion. The sEMG activity patterns of these muscles were examined in six young male elite rowers completing a 2 minute set at a moderate training intensity (23 stroke·min-1 and 1:47.500 m-1 split time, 300W). The rowers closely maintained the required target pace through visual inspection of the standard LCD display of each ergometer. The measurements of duration of each rowing cycle and onset of each stroke during the test were recorded simultaneously with the sEMG activity through the additional instrumentation of a foot-pressure switch and handle accelerometry. There were no significant differences between the two ergometer designs in group means for: work rate (i.e., rowing speed and stroke rate), metabolic load as measured by mean heart rate, rowing cycle duration, or timing of the stroke in the cycle. 2-D motion analysis of hip and knee motion for the rowing cycle from the video footage taken during the test also revealed no significant differences in the joint range of motion between the ergometers. Ensemble average sEMG activity profiles based on 30+ strokes were obtained for each participant and normalised per 10% intervals of the cycle duration as well as for peak mean sEMG amplitude for each muscle. A repeated measures ANOVA on the sEMG activity per 10% interval for the four muscles contributing to hip and trunk motion during the rowing cycle revealed no significant differences between the Concept 2C and Rowperfect (F = 0.070, df = 1,5, p = 0.802). The outcome of this study suggests that the two different ergometer designs are equally useful for dry land training. Key Points The effects of endurance training on HR recovery after exercise and cardiac ANS modulation were investigated in female marathon runners by comparing with untrained controls. Time and frequency domain analysis of HRV was used to investigate cardiac ANS modulation. As compared with untrained controls, the female marathon runners showed faster HR recovery after exercise, which should result from their higher levels of HRV, higher aerobic capacity and exaggerated blood pressure response to exercise. PMID:24431957

Diagnostic value of quantitative assessment of cardiac 18F-fluoro-2-deoxyglucose uptake in suspected cardiac sarcoidosis.

PubMed

Lebasnier, Adrien; Legallois, Damien; Bienvenu, Boris; Bergot, Emmanuel; Desmonts, Cédric; Zalcman, Gérard; Agostini, Denis; Manrique, Alain

2018-06-01

The identification of cardiac sarcoidosis is challenging as there is no gold standard consensually admitted for its diagnosis. The aim of this study was to evaluate the diagnostic value of the assessment of cardiac dynamic 18 F-fluoro-2-deoxyglucose positron emission tomography ( 18 F-FDG PET/CT) and net influx constant (Ki) in patients suspected of cardiac sarcoidosis. Data obtained from 30 biopsy-proven sarcoidosis patients suspected of cardiac sarcoidosis who underwent a 50-min list-mode cardiac dynamic 18 F-FDG PET/CT after a 24 h high-fat and low-carbohydrate diet were analyzed. A normalized coefficient of variation of quantitative glucose influx constant, calculated as the ratio: standard deviation of the segmental Ki (min -1 )/global Ki (min -1 ) was determined using a validated software (Carimas ® 2.4, Turku PET Centre). Cardiac sarcoidosis was diagnosed according to the Japanese Ministry of Health and Welfare criteria. Receiving operating curve analysis was performed to determine sensitivity and specificity of cardiac dynamic 18 F-FDG PET/CT analysis to diagnose cardiac sarcoidosis. Six out of 30 patients (20%) were diagnosed as having cardiac sarcoidosis. Myocardial glucose metabolism was significantly heterogeneous in patients with cardiac sarcoidosis who showed significantly higher normalized coefficient of variation values compared to patients without cardiac sarcoidosis (0.513 ± 0.175 vs. 0.205 ± 0.081; p = 0.0007). Using ROC curve analysis, we found a cut-off value of 0.38 for the diagnosis of cardiac sarcoidosis with a sensitivity of 100% and a specificity of 91%. Our results suggest that quantitative analysis of cardiac dynamic 18 F-FDG PET/CT could be a useful tool for the diagnosis of cardiac sarcoidosis.

Estimation of Cardiopulmonary Parameters From Ultra Wideband Radar Measurements Using the State Space Method.

PubMed

Naishadham, Krishna; Piou, Jean E; Ren, Lingyun; Fathy, Aly E

2016-12-01

Ultra wideband (UWB) Doppler radar has many biomedical applications, including remote diagnosis of cardiovascular disease, triage and real-time personnel tracking in rescue missions. It uses narrow pulses to probe the human body and detect tiny cardiopulmonary movements by spectral analysis of the backscattered electromagnetic (EM) field. With the help of super-resolution spectral algorithms, UWB radar is capable of increased accuracy for estimating vital signs such as heart and respiration rates in adverse signal-to-noise conditions. A major challenge for biomedical radar systems is detecting the heartbeat of a subject with high accuracy, because of minute thorax motion (less than 0.5 mm) caused by the heartbeat. The problem becomes compounded by EM clutter and noise in the environment. In this paper, we introduce a new algorithm based on the state space method (SSM) for the extraction of cardiac and respiration rates from UWB radar measurements. SSM produces range-dependent system poles that can be classified parametrically with spectral peaks at the cardiac and respiratory frequencies. It is shown that SSM produces accurate estimates of the vital signs without producing harmonics and inter-modulation products that plague signal resolution in widely used FFT spectrograms.

Characterization of piezoelectric device for implanted pacemaker energy harvesting

NASA Astrophysics Data System (ADS)

Jay, Sunny; Caballero, Manuel; Quinn, William; Barrett, John; Hill, Martin

2016-10-01

Novel implanted cardiac pacemakers that are powered by energy harvesters driven by the cardiac motion and have a 40 year lifetime are currently under development. To satisfy space constraints and energy requirements of the device, silicon-based MEMS energy harvesters are being developed in the EU project (MANpower1). Such MEMS harvesters for vibration frequencies below 50 Hz have not been widely reported. In this paper, an analytical model and a 3D finite element model (FEM) to predict displacement and open circuit voltage, validated through experimental analysis using an off-the-shelf low frequency energy harvester, are presented. The harvester was excited through constant amplitude sinusoidal base displacement over a range of 20 to 70 Hz passing through its first mode natural frequency at 47 Hz. At resonance both models predict displacements with an error of less than 2% when compared to the experimental result. Comparing the two models, the application of the experimentally measured damping ratio differs for accurate displacement prediction and the differences in symmetry in the measured and modelled displacement and voltage data around the resonance frequency indicate the two piezoelectric voltage models use different fundamental equations.

Stress Echocardiography for the Diagnosis of Coronary Artery Disease

PubMed Central

2010-01-01

Executive Summary In July 2009, the Medical Advisory Secretariat (MAS) began work on Non-Invasive Cardiac Imaging Technologies for the Diagnosis of Coronary Artery Disease (CAD), an evidence-based review of the literature surrounding different cardiac imaging modalities to ensure that appropriate technologies are accessed by patients suspected of having CAD. This project came about when the Health Services Branch at the Ministry of Health and Long-Term Care asked MAS to provide an evidentiary platform on effectiveness and cost-effectiveness of non-invasive cardiac imaging modalities. After an initial review of the strategy and consultation with experts, MAS identified five key non-invasive cardiac imaging technologies for the diagnosis of CAD. Evidence-based analyses have been prepared for each of these five imaging modalities: cardiac magnetic resonance imaging, single photon emission computed tomography, 64-slice computed tomographic angiography, stress echocardiography, and stress echocardiography with contrast. For each technology, an economic analysis was also completed (where appropriate). A summary decision analytic model was then developed to encapsulate the data from each of these reports (available on the OHTAC and MAS website). The Non-Invasive Cardiac Imaging Technologies for the Diagnosis of Coronary Artery Disease series is made up of the following reports, which can be publicly accessed at the MAS website at: www.health.gov.on.ca/mas"> www.health.gov.on.ca/mas or at www.health.gov.on.ca/english/providers/program/mas/mas_about.html Single Photon Emission Computed Tomography for the Diagnosis of Coronary Artery Disease: An Evidence-Based Analysis Stress Echocardiography for the Diagnosis of Coronary Artery Disease: An Evidence-Based Analysis Stress Echocardiography with Contrast for the Diagnosis of Coronary Artery Disease: An Evidence-Based Analysis 64-Slice Computed Tomographic Angiography for the Diagnosis of Coronary Artery Disease: An Evidence-Based Analysis Cardiac Magnetic Resonance Imaging for the Diagnosis of Coronary Artery Disease: An Evidence-Based Analysis Pease note that two related evidence-based analyses of non-invasive cardiac imaging technologies for the assessment of myocardial viability are also available on the MAS website: Positron Emission Tomography for the Assessment of Myocardial Viability: An Evidence-Based Analysis Magnetic Resonance Imaging for the Assessment of Myocardial Viability: an Evidence-Based Analysis The Toronto Health Economics and Technology Assessment Collaborative has also produced an associated economic report entitled: The Relative Cost-effectiveness of Five Non-invasive Cardiac Imaging Technologies for Diagnosing Coronary Artery Disease in Ontario [Internet]. Available from: http://theta.utoronto.ca/reports/?id=7 Objective The objective of the analysis is to determine the diagnostic accuracy of stress echocardiography (ECHO) in the diagnosis of patients with suspected coronary artery disease (CAD) compared to coronary angiography (CA). Stress Echocardiography Stress ECHO is a non-invasive technology that images the heart using ultrasound. It is one of the most commonly employed imaging techniques for investigating a variety of cardiac abnormalities in both community and hospital settings. A complete ECHO exam includes M-mode, 2-dimensional (2-D) images and Doppler imaging. In order to diagnosis CAD and assess whether myocardial ischemia is present, images obtained at rest are compared to those obtained during or immediately after stress. The most commonly used agents used to induce stress are exercise and pharmacological agents such as dobutamine and dipyridamole. The hallmark of stress-induced myocardial ischemia is worsening of wall motion abnormalities or the development of new wall motion abnormalities. A major challenge for stress ECHO is that the interpretation of wall motion contractility and function is subjective. This leads to inter-observer variability and reduced reproducibility. Further, it is estimated that approximately 30% of patients have sub-optimal stress ECHO exams. To overcome this limitation, contrast agents for LV opacification have been developed. Although stress ECHO is a relatively easy to use technology that poses only a low risk of adverse events compared to other imaging technologies, it may potentially be overused and/or misused in CAD diagnosis. Several recent advances have been made focusing on quantitative methods for assessment, improved image quality and enhanced portability, however, evidence on the effectiveness and clinical utility of these enhancements is limited. Evidence-Based Analysis Research Questions What is the diagnostic accuracy of stress ECHO for the diagnosis of patients with suspected CAD compared to the reference standard of CA? What is the clinical utility1 of stress ECHO? Literature Search A literature search was performed on August 28, 2009 using OVID MEDLINE, MEDLINE In-Process and Other Non-Indexed Citations, EMBASE, the Cumulative Index to Nursing & Allied Health Literature (CINAHL), the Cochrane Library, and the International Agency for Health Technology Assessment (INAHTA) for studies published from January 1, 2004 until August 21, 2009. Abstracts were reviewed by a single reviewer and, for those studies meeting the eligibility criteria, full-text articles were obtained. Reference lists were also examined for any relevant studies not identified through the search. Inclusion Criteria Systematic reviews, meta-analyses, randomized controlled trials, prospective observational studies, retrospective analyses Minimum sample size of 20 enrolled patients Comparison to CA (reference standard) Definition of CAD specified as either ≥50%, ≥70% or ≥75% coronary artery stenosis on CA Reporting accuracy data on individual patients (rather than accuracy data stratified by segments of the heart) English Human Exclusion Criteria Duplicate studies Non-systematic reviews, case reports Grey literature (e.g., conference abstracts) Insufficient data for independent calculation of sensitivity and specificity Use of ECHO for purposes other than diagnosis of CAD (e.g., arrhythmia, valvular disease, mitral stenosis, pre-operative risk of MI) Transesophageal ECHO since its primary use is for non-CAD indications such as endocarditis, intracardiac thrombi, valvular disorders Only resting ECHO performed Outcomes of Interest Accuracy outcomes (sensitivity, specificity, positive predictive value, negative predictive value) Costs Summary of Findings Given the vast amount of published literature on stress ECHO, it was decided to focus on the studies contained in the comprehensive 2007 review by Heijenbrok-Kal et al. (1) as a basis for the MAS evidence-based analysis. In applying our inclusion and exclusion criteria, 105 observational studies containing information on 13,035 patients were included. Six studies examined stress ECHO with adenosine, 26 with dipyridamole and 77 with dobutamine, the latter being the most commonly used pharmacological stress ECHO agent in Ontario. A further 18 studies employed exercise as the stressor.2 The prevalence of CAD ranged from 19% to 94% with a mean estimated prevalence of 70%. Based on the results of these studies the following conclusions were made: Based on the available evidence, stress ECHO is a useful imaging modality for the diagnosis of CAD in patients with suspected disease. The overall pooled sensitivity is 0.80 (95% CI: 0.77 – 0.82) and the pooled specificity is 0.84 (95% CI: 0.82 – 0.87) using CA as the reference standard. The AUC derived from the sROC curve is 0.895 and the DOR is 20.64. For pharmacological stress, the pooled sensitivity is 0.79 (95% CI: 0.71 – 0.87) and the pooled specificity is 0.85 (95% CI: 0.83 – 0.88). When exercise is employed as the stress agent, the pooled sensitivity is 0.81 (95% CI: 0.76– 0.86) and the pooled specificity is 0.79 (95% CI: 0.71 – 0.87). Although pharmacological stress and exercise stress would be indicated for different patient populations based on ability to exercise there were no significant differences in sensitivity and specificity. Based on clinical experts, diagnostic accuracy on stress ECHO depends on the patient population, the expertise of the interpreter and the quality of the image. PMID:23074412

Adult Health Learning and Transformation: A Case Study of a Canadian Community-Based Program

ERIC Educational Resources Information Center

Coady, Maureen

2013-01-01

This article describes a case study of adult learning in a Canadian multisite Community Cardiovascular Hearts in Motion program. The researcher highlights the informal learning of 40 adult participants in this 12-week community-based cardiac rehabilitation/education program in five rural Nova Scotia communities. The effects of this learning and…

Noninvasive Assessment of Tissue Heating During Cardiac Radiofrequency Ablation Using MRI Thermography

PubMed Central

Kolandaivelu, Aravindan; Zviman, Menekhem M.; Castro, Valeria; Lardo, Albert C.; Berger, Ronald D.; Halperin, Henry R.

2010-01-01

Background Failure to achieve properly localized, permanent tissue destruction is a common cause of arrhythmia recurrence after cardiac ablation. Current methods of assessing lesion size and location during cardiac radiofrequency ablation are unreliable or not suited for repeated assessment during the procedure. MRI thermography could be used to delineate permanent ablation lesions because tissue heating above 50°C is the cause of permanent tissue destruction during radiofrequency ablation. However, image artifacts caused by cardiac motion, the ablation electrode, and radiofrequency ablation currently pose a challenge to MRI thermography in the heart. In the current study, we sought to demonstrate the feasibility of MRI thermography during cardiac ablation. Methods and Results An MRI-compatible electrophysiology catheter and filtered radiofrequency ablation system was used to perform ablation in the left ventricle of 6 mongrel dogs in a 1.5-T MRI system. Fast gradient-echo imaging was performed before and during radiofrequency ablation, and thermography images were derived from the preheating and postheating images. Lesion extent by thermography was within 20% of the gross pathology lesion. Conclusions MR thermography appears to be a promising technique for monitoring lesion formation and may allow for more accurate placement and titration of ablation, possibly reducing arrhythmia recurrences. PMID:20657028

Fully automated motion correction in first-pass myocardial perfusion MR image sequences.

PubMed

Milles, Julien; van der Geest, Rob J; Jerosch-Herold, Michael; Reiber, Johan H C; Lelieveldt, Boudewijn P F

2008-11-01

This paper presents a novel method for registration of cardiac perfusion magnetic resonance imaging (MRI). The presented method is capable of automatically registering perfusion data, using independent component analysis (ICA) to extract physiologically relevant features together with their time-intensity behavior. A time-varying reference image mimicking intensity changes in the data of interest is computed based on the results of that ICA. This reference image is used in a two-pass registration framework. Qualitative and quantitative validation of the method is carried out using 46 clinical quality, short-axis, perfusion MR datasets comprising 100 images each. Despite varying image quality and motion patterns in the evaluation set, validation of the method showed a reduction of the average right ventricle (LV) motion from 1.26+/-0.87 to 0.64+/-0.46 pixels. Time-intensity curves are also improved after registration with an average error reduced from 2.65+/-7.89% to 0.87+/-3.88% between registered data and manual gold standard. Comparison of clinically relevant parameters computed using registered data and the manual gold standard show a good agreement. Additional tests with a simulated free-breathing protocol showed robustness against considerable deviations from a standard breathing protocol. We conclude that this fully automatic ICA-based method shows an accuracy, a robustness and a computation speed adequate for use in a clinical environment.

Development of a model of the coronary arterial tree for the 4D XCAT phantom

NASA Astrophysics Data System (ADS)

Fung, George S. K.; Segars, W. Paul; Gullberg, Grant T.; Tsui, Benjamin M. W.

2011-09-01

A detailed three-dimensional (3D) model of the coronary artery tree with cardiac motion has great potential for applications in a wide variety of medical imaging research areas. In this work, we first developed a computer-generated 3D model of the coronary arterial tree for the heart in the extended cardiac-torso (XCAT) phantom, thereby creating a realistic computer model of the human anatomy. The coronary arterial tree model was based on two datasets: (1) a gated cardiac dual-source computed tomography (CT) angiographic dataset obtained from a normal human subject and (2) statistical morphometric data of porcine hearts. The initial proximal segments of the vasculature and the anatomical details of the boundaries of the ventricles were defined by segmenting the CT data. An iterative rule-based generation method was developed and applied to extend the coronary arterial tree beyond the initial proximal segments. The algorithm was governed by three factors: (1) statistical morphometric measurements of the connectivity, lengths and diameters of the arterial segments; (2) avoidance forces from other vessel segments and the boundaries of the myocardium, and (3) optimality principles which minimize the drag force at the bifurcations of the generated tree. Using this algorithm, the 3D computational model of the largest six orders of the coronary arterial tree was generated, which spread across the myocardium of the left and right ventricles. The 3D coronary arterial tree model was then extended to 4D to simulate different cardiac phases by deforming the original 3D model according to the motion vector map of the 4D cardiac model of the XCAT phantom at the corresponding phases. As a result, a detailed and realistic 4D model of the coronary arterial tree was developed for the XCAT phantom by imposing constraints of anatomical and physiological characteristics of the coronary vasculature. This new 4D coronary artery tree model provides a unique simulation tool that can be used in the development and evaluation of instrumentation and methods for imaging normal and pathological hearts with myocardial perfusion defects.

Motion-adaptive spatio-temporal regularization for accelerated dynamic MRI.

PubMed

Asif, M Salman; Hamilton, Lei; Brummer, Marijn; Romberg, Justin

2013-09-01

Accelerated magnetic resonance imaging techniques reduce signal acquisition time by undersampling k-space. A fundamental problem in accelerated magnetic resonance imaging is the recovery of quality images from undersampled k-space data. Current state-of-the-art recovery algorithms exploit the spatial and temporal structures in underlying images to improve the reconstruction quality. In recent years, compressed sensing theory has helped formulate mathematical principles and conditions that ensure recovery of (structured) sparse signals from undersampled, incoherent measurements. In this article, a new recovery algorithm, motion-adaptive spatio-temporal regularization, is presented that uses spatial and temporal structured sparsity of MR images in the compressed sensing framework to recover dynamic MR images from highly undersampled k-space data. In contrast to existing algorithms, our proposed algorithm models temporal sparsity using motion-adaptive linear transformations between neighboring images. The efficiency of motion-adaptive spatio-temporal regularization is demonstrated with experiments on cardiac magnetic resonance imaging for a range of reduction factors. Results are also compared with k-t FOCUSS with motion estimation and compensation-another recently proposed recovery algorithm for dynamic magnetic resonance imaging. . Copyright © 2012 Wiley Periodicals, Inc.

Efficient physics-based tracking of heart surface motion for beating heart surgery robotic systems.

PubMed

Bogatyrenko, Evgeniya; Pompey, Pascal; Hanebeck, Uwe D

2011-05-01

Tracking of beating heart motion in a robotic surgery system is required for complex cardiovascular interventions. A heart surface motion tracking method is developed, including a stochastic physics-based heart surface model and an efficient reconstruction algorithm. The algorithm uses the constraints provided by the model that exploits the physical characteristics of the heart. The main advantage of the model is that it is more realistic than most standard heart models. Additionally, no explicit matching between the measurements and the model is required. The application of meshless methods significantly reduces the complexity of physics-based tracking. Based on the stochastic physical model of the heart surface, this approach considers the motion of the intervention area and is robust to occlusions and reflections. The tracking algorithm is evaluated in simulations and experiments on an artificial heart. Providing higher accuracy than the standard model-based methods, it successfully copes with occlusions and provides high performance even when all measurements are not available. Combining the physical and stochastic description of the heart surface motion ensures physically correct and accurate prediction. Automatic initialization of the physics-based cardiac motion tracking enables system evaluation in a clinical environment.

Multimodality imaging evaluation of Chagas disease: an expert consensus of Brazilian Cardiovascular Imaging Department (DIC) and the European Association of Cardiovascular Imaging (EACVI).

PubMed

Nunes, Maria Carmo P; Badano, Luigi Paolo; Marin-Neto, J Antonio; Edvardsen, Thor; Fernández-Golfín, Covadonga; Bucciarelli-Ducci, Chiara; Popescu, Bogdan A; Underwood, Richard; Habib, Gilbert; Zamorano, Jose Luis; Saraiva, Roberto Magalhães; Sabino, Ester Cerdeira; Botoni, Fernando A; Barbosa, Márcia Melo; Barros, Marcio Vinicius L; Falqueto, Eduardo; Simões, Marcus Vinicius; Schmidt, André; Rochitte, Carlos Eduardo; Rocha, Manoel Otávio Costa; Ribeiro, Antonio Luiz Pinho; Lancellotti, Patrizio

2018-04-01

To develop a document by Brazilian Cardiovascular Imaging Department (DIC) and the European Association of Cardiovascular Imaging (EACVI) to review and summarize the most recent evidences about the non-invasive assessment of patients with Chagas disease, with the intent to set up a framework for standardized cardiovascular imaging to assess cardiovascular morphologic and functional disturbances, as well as to guide the subsequent process of clinical decision-making. Chagas disease remains one of the most prevalent infectious diseases in Latin America, and has become a health problem in non-endemic countries. Dilated cardiomyopathy is the most severe manifestation of Chagas disease, which causes substantial disability and early mortality in the socially most productive population leading to a significant economical burden. Prompt and correct diagnosis of Chagas disease requires specialized clinical expertise to recognize the unique features of this disease. The appropriate and efficient use of cardiac imaging is pivotal for diagnosing the cardiac involvement in Chagas disease, to stage the disease, assess patients' prognosis and address management. Echocardiography is the most common imaging modality used to assess, and follow-up patients with Chagas disease. The presence of echocardiographic abnormalities is of utmost importance, since it allows to stage patients according to disease progression. In early stages of cardiac involvement, echocardiography may demonstrate segmental left ventricuar wall motion abnormalities, mainly in the basal segments of inferior, inferolateral walls, and the apex, which cannot be attributed to obstructive coronary artery arteries. The prevalence of segmental wall motion abnormalities varies according to the stage of the disease, reaching about 50% in patients with left ventricular dilatation and dysfunction. Speckle tracking echocardiography allows a more precise and quantitative measurement of the regional myocardial function. Since segmental wall motion abnormalities are frequent in Chagas disease, speckle tracking echocardiography may have an important clinical application in these patients, particularly in the indeterminate forms when abnormalities are more subtle. Speckle tracking echocardiography can also quantify the heterogeneity of systolic contraction, which is associated with the risk of arrhythmic events. Three-dimensional (3D) echocardiography is superior to conventional two-dimensional (2D) echocardiography for assessing more accurately the left ventricular apex and thus to detect apical aneurysms and thrombus in patients in whom ventricular foreshortening is suspected by 2D echocardiography. In addition, 3D echocardiography is more accurate than 2D Simpson s biplane rule for assessing left ventricular volumes and function in patients with significant wall motion abnormalities, including aneurysms with distorted ventricular geometry. Contrast echocardiography has the advantage to enhancement of left ventricular endocardial border, allowing for more accurate detection of ventricular aneurysms and thrombus in Chagas disease. Diastolic dysfunction is an important hallmark of Chagas disease even in its early phases. In general, left ventricular diastolic and systolic dysfunction coexist and isolated diastolic dysfunction is uncommon but may be present in patients with the indeterminate form. Right ventricular dysfunction may be detected early in the disease course, but in general, the clinical manifestations occur late at advanced stages of Chagas cardiomyopathy. Several echocardiographic parameters have been used to assess right ventricular function in Chagas disease, including qualitative evaluation, myocardial performance index, tissue Doppler imaging, tricuspid annular plane systolic excursion, and speckle tracking strain. Cardiac magnetic resonance (CMR) is useful to assess global and regional left ventricular function in patients with Chagas diseases. Myocardial fibrosis is a striking feature of Chagas cardiomyopathy and late gadolinium enhancement (LGE) is used to detect and quantify the extension of myocardial fibrosis. Myocardial fibrosis might have a role in risk stratification of patients with Chagas disease. Limited data are available regarding right ventricular function assessed by CMR in Chagas disease. Radionuclide ventriculography is used for global biventricular function assessment in patients with suspected or definite cardiac involvement in Chagas disease with suboptimal acoustic window and contraindication to CMR. Myocardial perfusion scintigraphy may improve risk stratification to define cardiac involvement in Chagas disease, especially in the patients with devices who cannot be submitted to CMR and in the clinical setting of Chagas patients whose main complaint is atypical chest pain. Detection of reversible ischemic defects predicts further deterioration of left ventricular systolic function and helps to avoid unnecessary cardiac catheterization and coronary angiography. Cardiac imaging is crucial to detect the cardiac involvement in patients with Chagas disease, stage the disease and stratify patient risk and address management. Unfortunately, most patients live in regions with limited access to imaging methods and point-of-care, simplified protocols, could improve the access of these remote populations to important information that could impact in the clinical management of the disease. Therefore, there are many fields for further research in cardiac imaging in Chagas disease. How to better provide an earlier diagnosis of cardiac involvement and improve patients risk stratification remains to be addressed using different images modalities.

Biophysics of cardiopulmonary resuscitation with periodic z-axis acceleration or abdominal compression at aortic resonant frequencies.

PubMed

Babbs, Charles F

2006-06-01

Periodic z-axis acceleration (pGz)-CPR involves an oscillating motion of a whole patient in the head-to-foot dimension on a mechanized table. The method is able to sustain blood flow and long-term survival during and after prolonged cardiac arrest in anesthetized pigs. However, the exact mechanism by which circulation of blood is created has remained unknown. To explain the hemodynamic mechanism of pGz-CPR and to suggest some theoretically useful improvements. Computer modeling using a hybrid analytical-numerical approach, based upon Newton's second law of motion for fluid columns in the aorta and vena cavae, Ohm's law for resistive flow through vascular beds, and a 10-compartment representation of the adult human circulation. This idealized 70-kg human model is exercised to explore the effects upon systemic perfusion pressure of whole body z-axis acceleration at frequencies ranging from 0.5 to 5 Hz. The results, in turn, suggested studies of abdominal compression at these frequencies. Blood motion induced in great vessels by periodic z-axis acceleration causes systemic perfusion when cardiac valves are competent. Blood flow is a function of the frequency of oscillation. At 3.5 Hz, periodic acceleration using +/-0.6G and +/-1.2 cm oscillations induces forward blood flow of 2.1L/min and systemic perfusion pressure of 47 mmHg. A form of resonance occurs at the frequency for peak-flow, in which the period of oscillation matches the round-trip transit time for reflected pulse waves in the aorta. For +/-1.0 G acceleration at 3.5 Hz, systemic perfusion pressure is 80 mmHg and forward flow is 3.8L/min in the adult human model with longitudinal z-axis motion of only +/-2 cm. Similar results can be obtained using abdominal compression to excite resonant pressure-volume waves in the aorta. For 20 mmHg abdominal pressure pulses at 3.8 Hz, systemic perfusion pressure is 7 mmHg and forward flow is 2.8L/min. pGz-CPR and high-frequency abdominal CPR are the physically realistic means of generating artificial circulation during cardiac arrest. These techniques have fundamental mechanisms and practical features quite different from those of conventional CPR and the potential to generate superior systemic perfusion.

Haemodynamic improvement of older, previously replaced mechanical mitral valves by removal of the subvalvular pannus in redo cardiac surgery.

PubMed

Kim, Jong Hun; Kim, Tae Youn; Choi, Jong Bum; Kuh, Ja Hong

2017-01-01

Patients requiring redo cardiac surgery for diseased heart valves other than mitral valves may show increased pressure gradients and reduced valve areas of previously placed mechanical mitral valves due to subvalvular pannus formation. We treated four women who had mechanical mitral valves inserted greater than or equal to 20 years earlier and who presented with circular pannus that protruded into the lower margin of the valve ring but did not impede leaflet motion. Pannus removal improved the haemodynamic function of the mitral valve. © The Author 2016. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

A low-cost universal cumulative gating circuit for small and large animal clinical imaging

NASA Astrophysics Data System (ADS)

Gioux, Sylvain; Frangioni, John V.

2008-02-01

Image-assisted diagnosis and therapy is becoming more commonplace in medicine. However, most imaging techniques suffer from voluntary or involuntary motion artifacts, especially cardiac and respiratory motions, which degrade image quality. Current software solutions either induce computational overhead or reject out-of-focus images after acquisition. In this study we demonstrate a hardware-only gating circuit that accepts multiple, pseudo-periodic signals and produces a single TTL (0-5 V) imaging window of accurate phase and period. The electronic circuit Gerber files described in this article and the list of components are available online at www.frangionilab.org.

Evaluation of segmental left ventricular wall motion by equilibrium gated radionuclide ventriculography.

PubMed

Van Nostrand, D; Janowitz, W R; Holmes, D R; Cohen, H A

1979-01-01

The ability of equilibrium gated radionuclide ventriculography to detect segmental left ventricular (LV) wall motion abnormalities was determined in 26 patients undergoing cardiac catheterization. Multiple gated studies obtained in 30 degrees right anterior oblique and 45 degrees left anterior oblique projections, played back in a movie format, were compared to the corresponding LV ventriculograms. The LV wall in the two projections was divided into eight segments. Each segment was graded as normal, hypokinetic, akinetic, dyskinetic, or indeterminate. Thirteen percent of the segments in the gated images were indeterminate; 24 out of 27 of these were proximal or distal inferior wall segments. There was exact agreement in 86% of the remaining segments. The sensitivity of the radionuclide technique for detecting normal versus any abnormal wall motion was 71%, with a specificity of 99%. Equilibrium gated ventriculography is an excellent noninvasive technique for evaluating segmental LV wall motion. It is least reliable in assessing the proximal inferior wall and interventricular septum.

Reduction of thoracic aorta motion artifact with high-pitch 128-slice dual-source computed tomographic angiography: a historical control study.

PubMed

Nakagawa, Junichiro; Tasaki, Osamu; Watanabe, Yoshiyuki; Azuma, Takeo; Ohnishi, Mitsuo; Ukai, Isao; Tahara, Kenichi; Ogura, Hiroshi; Kuwagata, Yasuyuki; Hamasaki, Toshimitsu; Shimazu, Takeshi

2013-01-01

Electrocardiogram-gated imaging combined with multi-detector row computed tomography (MDCT) has reduced cardiac motion artifacts, but it was not practical in the emergency setting. The purpose of this study was to evaluate the ability of a high-pitch, 128-slice dual-source CT (DSCT) scanner to reduce motion artifacts in patients admitted to the emergency room. This study comprised 100 patients suspected of having thoracic aorta lesions. We examined 47 patients with the 128-slice DSCT scanner (DSCT group), and 53 patients were examined with a 64-slice MDCT scanner (MDCT group). Six anatomic areas in the thoracic aorta were evaluated. Computed tomography images in the DSCT group were distinct, and significant differences were observed in images of all areas between the 2 groups except for the descending aorta. The high-pitch DSCT scanner can reduce motion artifacts of the thoracic aorta and enable radiological diagnosis even in patients with tachycardia and without breath hold.

Fluid Dynamics of the Heart and its Valves

NASA Astrophysics Data System (ADS)

Peskin, Charles S.

1997-11-01

The fluid dynamics of the heart involve the interaction of blood, a viscous incompressible fluid, with the flexible, elastic, fiber-reinforced heart valve leaflets that are immersed in that fluid. Neither the fluid motion nor the valve leaflet motion are known in advance: both must be computed simultaneously by solving their coupled equations of motion. This can be done by the immersed boundary method(Peskin CS and McQueen DM: A general method for the computer simulation of biological systems interacting with fluids. In: Biological Fluid Dynamics (Ellington CP and Pedley TJ, eds.), The Company of Biologists Limited, Cambridge UK, 1995, pp. 265-276.), which can be extended to incorporate the contractile fiber architecture of the muscular heart walls as well as the valve leaflets and the blood. In this way we arrive at a three-dimensional computer model of the heart(Peskin CS and McQueen DM: Fluid dynamics of the heart and its valves. In: Case Studies in Mathematical Modeling: Ecology, Physiology, and Cell Biology (Othmer HG, Adler FR, Lewis MA, and Dallon JC, eds.), Prentice-Hall, Englewood Cliffs NJ, 1996, pp. 309-337.), which can be used as a test chamber for the design of prosthetic cardiac valves, and also to study the function of the heart in health and in disease. Numerical solutions of the equations of cardiac fluid dynamics obtained by the immersed boundary method will be presented in the form of a video animation of the beating heart.

TH-CD-207A-03: A Surface Deformation Driven Respiratory Model for Organ Motion Tracking in Lung Cancer Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, H; Zhen, X; Zhou, L

Purpose: To propose and validate a novel real-time surface-mesh-based internal organ-external surface motion and deformation tracking method for lung cancer radiotherapy. Methods: Deformation vector fields (DVFs) which characterizes the internal and external motion are obtained by registering the internal organ and tumor contours and external surface meshes to a reference phase in the 4D CT images using a recent developed local topology preserved non-rigid point matching algorithm (TOP). A composite matrix is constructed by combing the estimated internal and external DVFs. Principle component analysis (PCA) is then applied on the composite matrix to extract principal motion characteristics and finally yieldmore » the respiratory motion model parameters which correlates the internal and external motion and deformation. The accuracy of the respiratory motion model is evaluated using a 4D NURBS-based cardiac-torso (NCAT) synthetic phantom and three lung cancer cases. The center of mass (COM) difference is used to measure the tumor motion tracking accuracy, and the Dice’s coefficient (DC), percent error (PE) and Housdourf’s distance (HD) are used to measure the agreement between the predicted and ground truth tumor shape. Results: The mean COM is 0.84±0.49mm and 0.50±0.47mm for the phantom and patient data respectively. The mean DC, PE and HD are 0.93±0.01, 0.13±0.03 and 1.24±0.34 voxels for the phantom, and 0.91±0.04, 0.17±0.07 and 3.93±2.12 voxels for the three lung cancer patients, respectively. Conclusions: We have proposed and validate a real-time surface-mesh-based organ motion and deformation tracking method with an internal-external motion modeling. The preliminary results conducted on a synthetic 4D NCAT phantom and 4D CT images from three lung cancer cases show that the proposed method is reliable and accurate in tracking both the tumor motion trajectory and deformation, which can serve as a potential tool for real-time organ motion and deformation monitoring in lung cancer radiotherapy. This work is supported in part by grant from VARIAN MEDICAL SYSTEMS INC, the National Natural Science Foundation of China (no 81428019 and no 81301940), the Guangdong Natural Science Foundation (2015A030313302)and the 2015 Pearl River S&T Nova Program of Guangzhou (201506010096).« less

Cardiac imaging at 7 Tesla: Single- and two-spoke radiofrequency pulse design with 16-channel parallel excitation.

PubMed

Schmitter, Sebastian; DelaBarre, Lance; Wu, Xiaoping; Greiser, Andreas; Wang, Dingxin; Auerbach, Edward J; Vaughan, J Thomas; Uğurbil, Kâmil; Van de Moortele, Pierre-François

2013-11-01

Higher signal to noise ratio (SNR) and improved contrast have been demonstrated at ultra-high magnetic fields (≥7 Tesla [T]) in multiple targets, often with multi-channel transmit methods to address the deleterious impact on tissue contrast due to spatial variations in B1 (+) profiles. When imaging the heart at 7T, however, respiratory and cardiac motion, as well as B0 inhomogeneity, greatly increase the methodological challenge. In this study we compare two-spoke parallel transmit (pTX) RF pulses with static B1 (+) shimming in cardiac imaging at 7T. Using a 16-channel pTX system, slice-selective two-spoke pTX pulses and static B1 (+) shimming were applied in cardiac CINE imaging. B1 (+) and B0 mapping required modified cardiac triggered sequences. Excitation homogeneity and RF energy were compared in different imaging orientations. Two-spoke pulses provide higher excitation homogeneity than B1 (+) shimming, especially in the more challenging posterior region of the heart. The peak value of channel-wise RF energy was reduced, allowing for a higher flip angle, hence increased tissue contrast. Image quality with two-spoke excitation proved to be stable throughout the entire cardiac cycle. Two-spoke pTX excitation has been successfully demonstrated in the human heart at 7T, with improved image quality and reduced RF pulse energy when compared with B1 (+) shimming. Copyright © 2013 Wiley Periodicals, Inc.

Cardiac Cycle Dependent Left Atrial Dynamics: Implications for Catheter Ablation of Atrial Fibrillation

PubMed Central

Patel, Amit R.; Fatemi, Omid; Norton, Patrick T.; West, J. Jason; Helms, Adam S.; Kramer, Christopher M.; Ferguson, John D.

2008-01-01

Background Left atrial volume (LAV) determines prognosis and response to therapy in atrial fibrillation. Integration of electro-anatomical maps with 3D-images rendered from CT and MRI is used to facilitate atrial fibrillation ablation. Objectives We measured LAV changes and regional motion during the cardiac cycle that might affect the accuracy of image integration and determined their relationship to standard LAV measurements. Methods MRI was performed in thirty patients with paroxysmal atrial fibrillation. Left atrial time-volume curves were generated and used to divide the left atrial function (LAEF) into pumping (PEF) and conduit (CEF) fractions and to determine the maximum LAV (LAMAX) and the pre-atrial contraction volume (PACV). LAV was measured using an MRI angiogram and traditional geometric models from echocardiography (area-length and ellipsoid). The in-plane displacement of the pulmonary veins, anterior left atrium, mitral annulus, and left atrial appendage was measured. Results LAMAX was 107±36ml and occurred at 42±5% of the RR interval. PACV was 86 ±34ml and occurred at 81±4% of the RR interval. LAEF was 45±10% and PEF was 31±10%. LAV measurements made from the MRI angiogram, area-length and ellipsoid models underestimated LAMAX by 21±25ml, 16±26ml, and 35±22ml, respectively. The anterior LA, mitral annulus, and left atrial appendage were significantly displaced during the cardiac cycle (8.8±2.0mm, 13.2±3.8mm, and 10.2±3.4mm, respectively); the pulmonary veins were not. Conclusions LAV changes significantly during the cardiac cycle and substantial regional variation in left atrial motion exists. Standard measurements of left atrial volume significantly underestimate LAMAX when compared to the gold standard measure of 3D-volumetrics. PMID:18486563

Cardiac cycle-dependent left atrial dynamics: implications for catheter ablation of atrial fibrillation.

PubMed

Patel, Amit R; Fatemi, Omid; Norton, Patrick T; West, J Jason; Helms, Adam S; Kramer, Christopher M; Ferguson, John D

2008-06-01

Left atrial (LA) volume determines prognosis and response to therapy for atrial fibrillation. Integration of electroanatomic maps with three-dimensional images rendered from computed tomography and magnetic resonance imaging (MRI) is used to facilitate atrial fibrillation ablation. The purpose of this study was to measure LA volume changes and regional motion during the cardiac cycle that might affect the accuracy of image integration and to determine their relationship to standard LA volume measurements. MRI was performed in 30 patients with paroxysmal atrial fibrillation. LA time-volume curves were generated and used to divide LA ejection fraction into pumping ejection fraction and conduit ejection fraction and to determine maximum LA volume (LA(max)) and preatrial contraction volume. LA volume was measured using an MRI angiogram and traditional geometric models from echocardiography (area-length model and ellipsoid model). In-plane displacement of the pulmonary veins, anterior left atrium, mitral annulus, and LA appendage was measured. LA(max) was 107 +/- 36 mL and occurred at 42% +/- 5% of the R-R interval. Preatrial contraction volume was 86 +/- 34 mL and occurred at 81% +/- 4% of the R-R interval. LA ejection fraction was 45% +/- 10%, and pumping ejection fraction was 31% +/- 10%. LA volume measurements made from MRI angiogram, area-length model, and ellipsoid model underestimated LA(max) by 21 +/- 25 mL, 16 +/- 26 mL, and 35 +/- 22 mL, respectively. Anterior LA, mitral annulus, and LA appendage were significantly displaced during the cardiac cycle (8.8 +/- 2.0 mm, 13.2 +/- 3.8 mm, and 10.2 +/- 3.4 mm, respectively); the pulmonary veins were not displaced. LA volume changes significantly during the cardiac cycle, and substantial regional variation in LA motion exists. Standard measurements of LA volume significantly underestimate LA(max) compared to the gold standard measure of three-dimensional volumetrics.

Multi-oriented windowed harmonic phase reconstruction for robust cardiac strain imaging.

PubMed

Cordero-Grande, Lucilio; Royuela-del-Val, Javier; Sanz-Estébanez, Santiago; Martín-Fernández, Marcos; Alberola-López, Carlos

2016-04-01

The purpose of this paper is to develop a method for direct estimation of the cardiac strain tensor by extending the harmonic phase reconstruction on tagged magnetic resonance images to obtain more precise and robust measurements. The extension relies on the reconstruction of the local phase of the image by means of the windowed Fourier transform and the acquisition of an overdetermined set of stripe orientations in order to avoid the phase interferences from structures outside the myocardium and the instabilities arising from the application of a gradient operator. Results have shown that increasing the number of acquired orientations provides a significant improvement in the reproducibility of the strain measurements and that the acquisition of an extended set of orientations also improves the reproducibility when compared with acquiring repeated samples from a smaller set of orientations. Additionally, biases in local phase estimation when using the original harmonic phase formulation are greatly diminished by the one here proposed. The ideas here presented allow the design of new methods for motion sensitive magnetic resonance imaging, which could simultaneously improve the resolution, robustness and accuracy of motion estimates. Copyright © 2015 Elsevier B.V. All rights reserved.

SU-E-J-26: A Novel Technique for Markerless Self-Sorted 4D-CBCT Using Patient Motion Modeling: A Feasibility Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, L; Zhang, Y; Harris, W

2015-06-15

Purpose: To develop an automatic markerless 4D-CBCT projection sorting technique by using a patient respiratory motion model extracted from the planning 4D-CT images. Methods: Each phase of onboard 4D-CBCT is considered as a deformation of one phase of the prior planning 4D-CT. The deformation field map (DFM) is represented as a linear combination of three major deformation patterns extracted from the planning 4D-CT using principle component analysis (PCA). The coefficients of the PCA deformation patterns are solved by matching the digitally reconstructed radiograph (DRR) of the deformed volume to the onboard projection acquired. The PCA coefficients are solved for eachmore » single projection, and are used for phase sorting. Projections at the peaks of the Z direction coefficient are sorted as phase 1 and other projections are assigned into 10 phase bins by dividing phases equally between peaks. The 4D digital extended-cardiac-torso (XCAT) phantom was used to evaluate the proposed technique. Three scenarios were simulated, with different tumor motion amplitude (3cm to 2cm), tumor spatial shift (8mm SI), and tumor body motion phase shift (2 phases) from prior to on-board images. Projections were simulated over 180 degree scan-angle for the 4D-XCAT. The percentage of accurately binned projections across entire dataset was calculated to represent the phase sorting accuracy. Results: With a changed tumor motion amplitude from 3cm to 2cm, markerless phase sorting accuracy was 100%. With a tumor phase shift of 2 phases w.r.t. body motion, the phase sorting accuracy was 100%. With a tumor spatial shift of 8mm in SI direction, phase sorting accuracy was 86.1%. Conclusion: The XCAT phantom simulation results demonstrated that it is feasible to use prior knowledge and motion modeling technique to achieve markerless 4D-CBCT phase sorting. National Institutes of Health Grant No. R01-CA184173 Varian Medical System.« less

A remote and non-contact method for obtaining the blood-pulse waveform with a laser Doppler vibrometer

NASA Astrophysics Data System (ADS)

Desjardins, Candida L.; Antonelli, Lynn T.; Soares, Edward

2007-02-01

The use of lasers to remotely and non-invasively detect the blood pressure waveform of humans and animals would provide a powerful diagnostic tool. Current blood pressure measurement tools, such as a cuff, are not useful for burn and trauma victims, and animals require catheterization to acquire accurate blood pressure information. The purpose of our sensor method and apparatus invention is to remotely and non-invasively detect the blood pulse waveform of both animals and humans. This device is used to monitor an animal or human's skin in proximity to an artery using radiation from a laser Doppler vibrometer (LDV). This system measures the velocity (or displacement) of the pulsatile motion of the skin, indicative of physiological parameters of the arterial motion in relation to the cardiac cycle. Tests have been conducted that measures surface velocity with an LDV and a signal-processing unit, with enhanced detection obtained with optional hardware including a retro-reflector dot. The blood pulse waveform is obtained by integrating the velocity signal to get surface displacement using standard signal processing techniques. Continuous recording of the blood pulse waveform yields data containing information on cardiac health and can be analyzed to identify important events in the cardiac cycle, such as heart rate, the timing of peak systole, left ventricular ejection time and aortic valve closure. Experimental results are provided that demonstrates the current capabilities of the optical, non-contact sensor for the continuous, non-contact recording of the blood pulse waveform without causing patient distress.

Unique strain history during ejection in canine left ventricle.

PubMed

Douglas, A S; Rodriguez, E K; O'Dell, W; Hunter, W C

1991-05-01

Understanding the relationship between structure and function in the heart requires a knowledge of the connection between the local behavior of the myocardium (e.g., shortening) and the pumping action of the left ventricle. We asked the question, how do changes in preload and afterload affect the relationship between local myocardial deformation and ventricular volume? To study this, a set of small radiopaque beads was implanted in approximately 1 cm3 of the isolated canine heart left ventricular free wall. Using biplane cineradiography, we tracked the motion of these markers through various cardiac cycles (controlling pre- and afterload) using the relative motion of six markers to quantify the local three dimensional Lagrangian strain. Two different reference states (used to define the strains) were considered. First, we used the configuration of the heart at end diastole for that particular cardiac cycle to define the individual strains (which gave the local "shortening fraction") and the ejection fraction. Second, we used a single reference state for all cardiac cycles i.e., the end-diastolic state at maximum volume, to define absolute strains (which gave local fractional length) and the volume fraction. The individual strain versus ejection fraction trajectories were dependent on preload and afterload. For any one heart, however, each component of absolute strain was more tightly correlated to volume fraction. Around each linear regression, the individual measurements of absolute strain scattered with standard errors that averaged less than 7% of their range. Thus the canine hearts examined had a preferred kinematic (shape) history during ejection, different from the kinematics of filling and independent or pre-or afterload and of stroke volume.

Challenges in measuring individual differences in functional connectivity using fMRI: The case of healthy aging

PubMed Central

Tsvetanov, Kamen A.; Cam‐CAN; Henson, Richard N.

2017-01-01

Abstract Many studies report individual differences in functional connectivity, such as those related to age. However, estimates of connectivity from fMRI are confounded by other factors, such as vascular health, head motion and changes in the location of functional regions. Here, we investigate the impact of these confounds, and pre‐processing strategies that can mitigate them, using data from the Cambridge Centre for Ageing & Neuroscience (www.cam-can.com). This dataset contained two sessions of resting‐state fMRI from 214 adults aged 18–88. Functional connectivity between all regions was strongly related to vascular health, most likely reflecting respiratory and cardiac signals. These variations in mean connectivity limit the validity of between‐participant comparisons of connectivity estimates, and were best mitigated by regression of mean connectivity over participants. We also showed that high‐pass filtering, instead of band‐pass filtering, produced stronger and more reliable age‐effects. Head motion was correlated with gray‐matter volume in selected brain regions, and with various cognitive measures, suggesting that it has a biological (trait) component, and warning against regressing out motion over participants. Finally, we showed that the location of functional regions was more variable in older adults, which was alleviated by smoothing the data, or using a multivariate measure of connectivity. These results demonstrate that analysis choices have a dramatic impact on connectivity differences between individuals, ultimately affecting the associations found between connectivity and cognition. It is important that fMRI connectivity studies address these issues, and we suggest a number of ways to optimize analysis choices. Hum Brain Mapp 38:4125–4156, 2017. © 2017 Wiley Periodicals, Inc. PMID:28544076

Automatic localization of the left ventricular blood pool centroid in short axis cardiac cine MR images.

PubMed

Tan, Li Kuo; Liew, Yih Miin; Lim, Einly; Abdul Aziz, Yang Faridah; Chee, Kok Han; McLaughlin, Robert A

2018-06-01

In this paper, we develop and validate an open source, fully automatic algorithm to localize the left ventricular (LV) blood pool centroid in short axis cardiac cine MR images, enabling follow-on automated LV segmentation algorithms. The algorithm comprises four steps: (i) quantify motion to determine an initial region of interest surrounding the heart, (ii) identify potential 2D objects of interest using an intensity-based segmentation, (iii) assess contraction/expansion, circularity, and proximity to lung tissue to score all objects of interest in terms of their likelihood of constituting part of the LV, and (iv) aggregate the objects into connected groups and construct the final LV blood pool volume and centroid. This algorithm was tested against 1140 datasets from the Kaggle Second Annual Data Science Bowl, as well as 45 datasets from the STACOM 2009 Cardiac MR Left Ventricle Segmentation Challenge. Correct LV localization was confirmed in 97.3% of the datasets. The mean absolute error between the gold standard and localization centroids was 2.8 to 4.7 mm, or 12 to 22% of the average endocardial radius. Graphical abstract Fully automated localization of the left ventricular blood pool in short axis cardiac cine MR images.

A method to quantify mechanobiologic forces during zebrafish cardiac development using 4-D light sheet imaging and computational modeling

PubMed Central

Vedula, Vijay; Lee, Juhyun; Xu, Hao; Hsiai, Tzung K.

2017-01-01

Blood flow and mechanical forces in the ventricle are implicated in cardiac development and trabeculation. However, the mechanisms of mechanotransduction remain elusive. This is due in part to the challenges associated with accurately quantifying mechanical forces in the developing heart. We present a novel computational framework to simulate cardiac hemodynamics in developing zebrafish embryos by coupling 4-D light sheet imaging with a stabilized finite element flow solver, and extract time-dependent mechanical stimuli data. We employ deformable image registration methods to segment the motion of the ventricle from high resolution 4-D light sheet image data. This results in a robust and efficient workflow, as segmentation need only be performed at one cardiac phase, while wall position in the other cardiac phases is found by image registration. Ventricular hemodynamics are then quantified by numerically solving the Navier-Stokes equations in the moving wall domain with our validated flow solver. We demonstrate the applicability of the workflow in wild type zebrafish and three treated fish types that disrupt trabeculation: (a) chemical treatment using AG1478, an ErbB2 signaling inhibitor that inhibits proliferation and differentiation of cardiac trabeculation; (b) injection of gata1a morpholino oligomer (gata1aMO) suppressing hematopoiesis and resulting in attenuated trabeculation; (c) weak-atriumm58 mutant (wea) with inhibited atrial contraction leading to a highly undeveloped ventricle and poor cardiac function. Our simulations reveal elevated wall shear stress (WSS) in wild type and AG1478 compared to gata1aMO and wea. High oscillatory shear index (OSI) in the grooves between trabeculae, compared to lower values on the ridges, in the wild type suggest oscillatory forces as a possible regulatory mechanism of cardiac trabeculation development. The framework has broad applicability for future cardiac developmental studies focused on quantitatively investigating the role of hemodynamic forces and mechanotransduction during morphogenesis. PMID:29084212

Effects of testosterone and nandrolone on cardiac function: a randomized, placebo-controlled study.

PubMed

Chung, T; Kelleher, S; Liu, P Y; Conway, A J; Kritharides, L; Handelsman, D J

2007-02-01

Androgens have striking effects on skeletal muscle, but the effects on human cardiac muscle function are not well defined, neither has the role of metabolic activation (aromatization, 5alpha reduction) of testosterone on cardiac muscle been directly studied. To assess the effects of testosterone and nandrolone, a non-amplifiable and non-aromatizable pure androgen, on cardiac muscle function in healthy young men. Double-blind, randomized, placebo-controlled, three-arm parallel group clinical trial. Ambulatory care research centre. Healthy young men randomized into three groups of 10 men. Weekly intramuscular injections of testosterone (200 mg mixed esters), nandrolone (200 mg nandrolone decanoate) or matching (2 ml arachis oil vehicle) placebo for 4 weeks. Comprehensive measures of cardiac muscle function involving transthoracic cardiac echocardiography measuring myocardial tissue velocity, peak systolic strain and strain rates, and bioimpedance measurement of cardiac output and systematic vascular resistance. Left ventricular (LV) function (LV ejection fraction, LV modified TEI index), right ventricular (RV) function (ejection area, tricuspid annular systolic planar motion, RV modified TEI index) as well as cardiac afterload (mean arterial pressure, systemic vascular resistance) and overall cardiac contractility (stroke volume, cardiac output) were within age- and gender-specific reference ranges and were not significantly (P < 0.05) altered by either androgen or placebo over 4 weeks of treatment. Minor changes remaining within normal range were observed solely within the testosterone group for: increased LV end-systolic diameter (30 +/- 7 vs. 33 +/- 5 mm, P = 0.04) and RV end-systolic area (12.8 +/- 1.3 vs. 14.6 +/- 3.3 cm(2), P = 0.04), reduced LV diastolic septal velocity (Em, 9.5 +/- 2.6 vs. 8.7 +/- 2.0 cm/s, P = 0.006), increased LV filling pressure (E/Em ratio, 7.1 +/- 1.6 vs. 8.3 +/- 1.8, P = 0.02) and shortened PR interval on the electrocardiogram (167 +/- 13 vs. 154 +/- 12, P = 0.03). Four weeks of treatment with testosterone or nandrolone had no beneficial or adverse effects compared with placebo on cardiac function in healthy young men.

Compensation for Unconstrained Catheter Shaft Motion in Cardiac Catheters

PubMed Central

Degirmenci, Alperen; Loschak, Paul M.; Tschabrunn, Cory M.; Anter, Elad; Howe, Robert D.

2016-01-01

Cardiac catheterization with ultrasound (US) imaging catheters provides real time US imaging from within the heart, but manually navigating a four degree of freedom (DOF) imaging catheter is difficult and requires extensive training. Existing work has demonstrated robotic catheter steering in constrained bench top environments. Closed-loop control in an unconstrained setting, such as patient vasculature, remains a significant challenge due to friction, backlash, and physiological disturbances. In this paper we present a new method for closed-loop control of the catheter tip that can accurately and robustly steer 4-DOF cardiac catheters and other flexible manipulators despite these effects. The performance of the system is demonstrated in a vasculature phantom and an in vivo porcine animal model. During bench top studies the robotic system converged to the desired US imager pose with sub-millimeter and sub-degree-level accuracy. During animal trials the system achieved 2.0 mm and 0.65° accuracy. Accurate and robust robotic navigation of flexible manipulators will enable enhanced visualization and treatment during procedures. PMID:27525170

Vibration-synchronized magnetic resonance imaging for the detection of myocardial elasticity changes.

PubMed

Elgeti, Thomas; Tzschätzsch, Heiko; Hirsch, Sebastian; Krefting, Dagmar; Klatt, Dieter; Niendorf, Thoralf; Braun, Jürgen; Sack, Ingolf

2012-04-01

Vibration synchronized magnetic resonance imaging of harmonically oscillating tissue interfaces is proposed for cardiac magnetic resonance elastography. The new approach exploits cardiac triggered cine imaging synchronized with extrinsic harmonic stimulation (f = 22.83 Hz) to display oscillatory tissue deformations in magnitude images. Oscillations are analyzed by intensity threshold-based image processing to track wave amplitude variations over the cardiac cycle. In agreement to literature data, results in 10 volunteers showed that endocardial wave amplitudes during systole (0.13 ± 0.07 mm) were significantly lower than during diastole (0.34 ± 0.14 mm, P < 0.001). Wave amplitudes were found to decrease 117 ± 40 ms before myocardial contraction and to increase 75 ± 31 ms before myocardial relaxation. Vibration synchronized magnetic resonance imaging improves the temporal resolution of magnetic resonance elastography as it overcomes the use of extra motion encoding gradients, is less sensitive to susceptibility artifacts, and does not suffer from dynamic range constraints frequently encountered in phase-based magnetic resonance elastography. Copyright © 2012 Wiley Periodicals, Inc.

Ultra-wideband sensors for improved magnetic resonance imaging, cardiovascular monitoring and tumour diagnostics.

PubMed

Thiel, Florian; Kosch, Olaf; Seifert, Frank

2010-01-01

The specific advantages of ultra-wideband electromagnetic remote sensing (UWB radar) make it a particularly attractive technique for biomedical applications. We partially review our activities in utilizing this novel approach for the benefit of high and ultra-high field magnetic resonance imaging (MRI) and other applications, e.g., for intensive care medicine and biomedical research. We could show that our approach is beneficial for applications like motion tracking for high resolution brain imaging due to the non-contact acquisition of involuntary head motions with high spatial resolution, navigation for cardiac MRI due to our interpretation of the detected physiological mechanical contraction of the heart muscle and for MR safety, since we have investigated the influence of high static magnetic fields on myocardial mechanics. From our findings we could conclude, that UWB radar can serve as a navigator technique for high and ultra-high field magnetic resonance imaging and can be beneficial preserving the high resolution capability of this imaging modality. Furthermore it can potentially be used to support standard ECG analysis by complementary information where sole ECG analysis fails. Further analytical investigations have proven the feasibility of this method for intracranial displacements detection and the rendition of a tumour's contrast agent based perfusion dynamic. Beside these analytical approaches we have carried out FDTD simulations of a complex arrangement mimicking the illumination of a human torso model incorporating the geometry of the antennas applied.

Patient-specific CFD models for intraventricular flow analysis from 3D ultrasound imaging: Comparison of three clinical cases.

PubMed

Bavo, A M; Pouch, A M; Degroote, J; Vierendeels, J; Gorman, J H; Gorman, R C; Segers, P

2017-01-04

As the intracardiac flow field is affected by changes in shape and motility of the heart, intraventricular flow features can provide diagnostic indications. Ventricular flow patterns differ depending on the cardiac condition and the exploration of different clinical cases can provide insights into how flow fields alter in different pathologies. In this study, we applied a patient-specific computational fluid dynamics model of the left ventricle and mitral valve, with prescribed moving boundaries based on transesophageal ultrasound images for three cardiac pathologies, to verify the abnormal flow patterns in impaired hearts. One case (P1) had normal ejection fraction but low stroke volume and cardiac output, P2 showed low stroke volume and reduced ejection fraction, P3 had a dilated ventricle and reduced ejection fraction. The shape of the ventricle and mitral valve, together with the pathology influence the flow field in the left ventricle, leading to distinct flow features. Of particular interest is the pattern of the vortex formation and evolution, influenced by the valvular orifice and the ventricular shape. The base-to-apex pressure difference of maximum 2mmHg is consistent with reported data. We used a CFD model with prescribed boundary motion to describe the intraventricular flow field in three patients with impaired diastolic function. The calculated intraventricular flow dynamics are consistent with the diagnostic patient records and highlight the differences between the different cases. The integration of clinical images and computational techniques, therefore, allows for a deeper investigation intraventricular hemodynamics in patho-physiology. Copyright © 2016 Elsevier Ltd. All rights reserved.

Longitudinal and transverse right ventricular function in pulmonary hypertension: cardiovascular magnetic resonance imaging study from the ASPIRE registry

PubMed Central

Rajaram, Smitha; Capener, Dave; Elliot, Charlie; Condliffe, Robin; Wild, Jim M.; Kiely, David G.

2015-01-01

Abstract Right ventricular (RV) function is a strong predictor of outcome in cardiovascular diseases. Two components of RV function, longitudinal and transverse motion, have been investigated in pulmonary hypertension (PH). However, their individual clinical significance remains uncertain. The aim of this study was to determine the factors associated with transverse and longitudinal RV motion in patients with PH. In 149 treatment-naive patients with PH and 16 patients with suspected PH found to have mean pulmonary arterial pressure of <20 mmHg, cardiovascular magnetic resonance imaging was performed within 24 hours of right heart catheterization. In patients with PH, fractional longitudinal motion (fractional tricuspid annulus to apex distance [f-TAAD]) was significantly greater than fractional transverse motion (fractional septum to free wall distance [f-SFD]; P = 0.002). In patients without PH, no significant difference between f-SFD and f-TAAD was identified (P = 0.442). Longitudinal RV motion was singularly associated with RV ejection fraction independent of age, invasive hemodynamics, and cardiac magnetic resonance measurements (P = 0.024). In contrast, transverse RV motion was independently associated with left ventricular eccentricity (P = 0.036) in addition to RV ejection fraction (P = 0.014). In conclusion, RV motion is significantly greater in the longitudinal direction in patients with PH, whereas patients without PH have equal contributions of transverse and longitudinal motion. Longitudinal RV motion is primarily associated with global RV pump function in PH. Transverse RV motion not only reflects global pump function but is independently influenced by ventricular interaction in patients with PH. PMID:26401257

Longitudinal and transverse right ventricular function in pulmonary hypertension: cardiovascular magnetic resonance imaging study from the ASPIRE registry.

PubMed

Swift, Andrew J; Rajaram, Smitha; Capener, Dave; Elliot, Charlie; Condliffe, Robin; Wild, Jim M; Kiely, David G

2015-09-01

Right ventricular (RV) function is a strong predictor of outcome in cardiovascular diseases. Two components of RV function, longitudinal and transverse motion, have been investigated in pulmonary hypertension (PH). However, their individual clinical significance remains uncertain. The aim of this study was to determine the factors associated with transverse and longitudinal RV motion in patients with PH. In 149 treatment-naive patients with PH and 16 patients with suspected PH found to have mean pulmonary arterial pressure of <20 mmHg, cardiovascular magnetic resonance imaging was performed within 24 hours of right heart catheterization. In patients with PH, fractional longitudinal motion (fractional tricuspid annulus to apex distance [f-TAAD]) was significantly greater than fractional transverse motion (fractional septum to free wall distance [f-SFD]; P = 0.002). In patients without PH, no significant difference between f-SFD and f-TAAD was identified (P = 0.442). Longitudinal RV motion was singularly associated with RV ejection fraction independent of age, invasive hemodynamics, and cardiac magnetic resonance measurements (P = 0.024). In contrast, transverse RV motion was independently associated with left ventricular eccentricity (P = 0.036) in addition to RV ejection fraction (P = 0.014). In conclusion, RV motion is significantly greater in the longitudinal direction in patients with PH, whereas patients without PH have equal contributions of transverse and longitudinal motion. Longitudinal RV motion is primarily associated with global RV pump function in PH. Transverse RV motion not only reflects global pump function but is independently influenced by ventricular interaction in patients with PH.

Risk stratification for therapeutic management and prognosis.

PubMed

Coelho-Filho, Otavio R; Nallamshetty, Leelakrishna; Kwong, Raymond Y

2009-07-01

In coronary artery disease (CAD), cardiac magnetic resonance (CMR) imaging can integrate several types of pulse-sequence examinations (eg, myocardial perfusion, cine wall motion, T2-weighted imaging for myocardial edema, late gadolinium enhancement, and CMR angiography) that can provide anatomic, functional, and physiologic information about the heart in a single imaging session. Because of this ability to interrogate myocardial physiology using different pulse sequence techniques within a single CMR session, this technique has been recognized increasingly in many centers as the test of choice for assessing patients who present with cardiomyopathy of undetermined cause. This article first reviews the current evidence supporting the prognosticating role of CMR in assessing CAD and then discusses CMR applications and prognostication in many non-coronary cardiac conditions.

Audit of cardiac pathology detection using a criteria-based perioperative echocardiography service.

PubMed

Faris, J G; Hartley, K; Fuller, C M; Langston, R B; Royse, C F; Veltman, M G

2012-07-01

Transthoracic echocardiography is often used to screen patients prior to non-cardiac surgery to detect conditions associated with perioperative haemodynamic compromise and to stratify risk. However, anaesthetists' use of echocardiography is quite variable. A consortium led by the American College of Cardiology Foundation has developed appropriate use criteria for echocardiography. At Joondalup Hospital in Western Australia, we have used these criteria to order echocardiographic studies in patients attending our anaesthetic pre-admission clinic. We undertook this audit to determine the incidence of significant echocardiographic findings using this approach. In a 22-month period, 606 transthoracic echocardiographic studies were performed. This represented 8.7% of clinic attendees and 1.7% of all surgical patients. In about two-thirds of the patients, the indication for echocardiography was identified on the basis of a telephone screening questionnaire. The most common indications were poor exercise tolerance (27.4%), ischaemic heart disease (20.9%) and cardiac murmurs (16.3%). Over 26% of patients studied had significant cardiac pathology (i.e. moderate or severe echocardiographic findings), most importantly moderate or severe aortic stenosis (8.6%), poor left ventricular function (7.1%), a regional wall motion abnormality (4.3%) or moderate or severe mitral regurgitation (4.1%). Using appropriate use criteria to guide ordering transthoracic echocardiography studies led to a high detection rate of clinically important cardiac pathology in our perioperative service.

3D force control for robotic-assisted beating heart surgery based on viscoelastic tissue model.

PubMed

Liu, Chao; Moreira, Pedro; Zemiti, Nabil; Poignet, Philippe

2011-01-01

Current cardiac surgery faces the challenging problem of heart beating motion even with the help of mechanical stabilizer which makes delicate operation on the heart surface difficult. Motion compensation methods for robotic-assisted beating heart surgery have been proposed recently in literature, but research on force control for such kind of surgery has hardly been reported. Moreover, the viscoelasticity property of the interaction between organ tissue and robotic instrument further complicates the force control design which is much easier in other applications by assuming the interaction model to be elastic (industry, stiff object manipulation, etc.). In this work, we present a three-dimensional force control method for robotic-assisted beating heart surgery taking into consideration of the viscoelastic interaction property. Performance studies based on our D2M2 robot and 3D heart beating motion information obtained through Da Vinci™ system are provided.

Detection of MRI artifacts produced by intrinsic heart motion using a saliency model

NASA Astrophysics Data System (ADS)

Salguero, Jennifer; Velasco, Nelson; Romero, Eduardo

2017-11-01

Cardiac Magnetic Resonance (CMR) requires synchronization with the ECG to correct many types of noise. However, the complex heart motion frequently produces displaced slices that have to be either ignored or manually corrected since the ECG correction is useless in this case. This work presents a novel methodology that detects the motion artifacts in CMR using a saliency method that highlights the region where the heart chambers are located. Once the Region of Interest (RoI) is set, its center of gravity is determined for the set of slices composing the volume. The deviation of the gravity center is an estimation of the coherence between the slices and is used to find out slices with certain displacement. Validation was performed with distorted real images where a slice is artificially misaligned with respect to set of slices. The displaced slice is found with a Recall of 84% and F Score of 68%.

Kinin B1 receptor blockade and ACE inhibition attenuate cardiac postinfarction remodeling and heart failure in rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Xinchun

Introduction: The aim of the present study was to evaluate the effects of the novel kinin B1 receptor antagonist BI113823 on postinfarction cardiac remodeling and heart failure, and to determine whether B1 receptor blockade alters the cardiovascular effects of an angiotensin 1 converting enzyme (ACE) inhibitor in rats. Methods and results: Sprague Dawley rats were subjected to permanent occlusion of the left coronary artery. Cardiovascular function was determined at 6 weeks postinfarction. Treatment with either B1 receptor antagonist (BI113823) or an ACE inhibitor (lisinopril) alone or in combination significantly reduced the heart weight-to-body weight and lung weight-to-body weight ratios, andmore » improved postinfarction cardiac function as evidenced by greater cardiac output, the maximum rate of left ventricular pressure rise (± dP/dtmax), left ventricle ejection fraction, fractional shorting, better wall motion, and attenuation of elevated left ventricular end diastolic pressure (LVEDP). Furthermore, all three treatment groups exhibited significant reduction in cardiac interstitial fibrosis, collagen deposition, CD68 positive macrophages, neutrophils, and proinflammatory cytokine production (TNF-α and IL-1β), compared to vehicle controls. Conclusion: The present study shows that treatment with the novel kinin B1 receptor antagonist, BI113823, reduces postinfarction cardiac remodeling and heart failure, and does not influence the cardiovascular effects of the ACE inhibitor. - Highlights: • We examined the role of kinin B1 receptors in the development of heart failure. • Kinin B1 receptor blockade attenuates post-infarction cardiac remodeling. • Kinin B1 receptor blockade improves dysfunction, and prevented heart failure. • B1 receptor blockade does not affect the cardio-protection of an ACE inhibitor.« less

Adaptive motion artifact reducing algorithm for wrist photoplethysmography application

NASA Astrophysics Data System (ADS)

Zhao, Jingwei; Wang, Guijin; Shi, Chenbo

2016-04-01

Photoplethysmography (PPG) technology is widely used in wearable heart pulse rate monitoring. It might reveal the potential risks of heart condition and cardiopulmonary function by detecting the cardiac rhythms in physical exercise. However the quality of wrist photoelectric signal is very sensitive to motion artifact since the thicker tissues and the fewer amount of capillaries. Therefore, motion artifact is the major factor that impede the heart rate measurement in the high intensity exercising. One accelerometer and three channels of light with different wavelengths are used in this research to analyze the coupled form of motion artifact. A novel approach is proposed to separate the pulse signal from motion artifact by exploiting their mixing ratio in different optical paths. There are four major steps of our method: preprocessing, motion artifact estimation, adaptive filtering and heart rate calculation. Five healthy young men are participated in the experiment. The speeder in the treadmill is configured as 12km/h, and all subjects would run for 3-10 minutes by swinging the arms naturally. The final result is compared with chest strap. The average of mean square error (MSE) is less than 3 beats per minute (BPM/min). Proposed method performed well in intense physical exercise and shows the great robustness to individuals with different running style and posture.

Whole left ventricular functional assessment from two minutes free breathing multi-slice CINE acquisition

NASA Astrophysics Data System (ADS)

Usman, M.; Atkinson, D.; Heathfield, E.; Greil, G.; Schaeffter, T.; Prieto, C.

2015-04-01

Two major challenges in cardiovascular MRI are long scan times due to slow MR acquisition and motion artefacts due to respiratory motion. Recently, a Motion Corrected-Compressed Sensing (MC-CS) technique has been proposed for free breathing 2D dynamic cardiac MRI that addresses these challenges by simultaneously accelerating MR acquisition and correcting for any arbitrary motion in a compressed sensing reconstruction. In this work, the MC-CS framework is combined with parallel imaging for further acceleration, and is termed Motion Corrected Sparse SENSE (MC-SS). Validation of the MC-SS framework is demonstrated in eight volunteers and three patients for left ventricular functional assessment and results are compared with the breath-hold acquisitions as reference. A non-significant difference (P > 0.05) was observed in the volumetric functional measurements (end diastolic volume, end systolic volume, ejection fraction) and myocardial border sharpness values obtained with the proposed and gold standard methods. The proposed method achieves whole heart multi-slice coverage in 2 min under free breathing acquisition eliminating the time needed between breath-holds for instructions and recovery. This results in two-fold speed up of the total acquisition time in comparison to the breath-hold acquisition.

[Evaluation of echocardiographic left ventricular wall motion analysis supported by internet picture viewing system].

PubMed

Hirano, Yutaka; Ikuta, Shin-Ichiro; Nakano, Manabu; Akiyama, Seita; Nakamura, Hajime; Nasu, Masataka; Saito, Futoshi; Nakagawa, Junichi; Matsuzaki, Masashi; Miyazaki, Shunichi

2007-02-01

Assessment of deterioration of regional wall motion by echocardiography is not only subjective but also features difficulties with interobserver agreement. Progress in digital communication technology has made it possible to send video images from a distant location via the Internet. The possibility of evaluating left ventricular wall motion using video images sent via the Internet to distant institutions was evaluated. Twenty-two subjects were randomly selected. Four sets of video images (parasternal long-axis view, parasternal short-axis view, apical four-chamber view, and apical two-chamber view) were taken for one cardiac cycle. The images were sent via the Internet to two institutions (observer C in facility A and observers D and E in facility B) for evaluation. Great care was taken to prevent disclosure of patient information to these observers. Parasternal long-axis images were divided into four segments, and the parasternal short-axis view, apical four-chamber view, and apical two-chamber view were divided into six segments. One of the following assessments, normokinesis, hypokinesis, akinesis, or dyskinesis, was assigned to each segment. The interobserver rates of agreement in judgments between observers C and D, observers C and E, and intraobserver agreement rate (for observer D) were calculated. The rate of interobserver agreement was 85.7% (394/460 segments; Kappa = 0.65) between observers C and D, 76.7% (353/460 segments; Kappa = 0.39) between observers D and E, and 76.3% (351/460 segments; Kappa = 0.36)between observers C and E, and intraobserver agreement was 94.3% (434/460; Kappa = 0.86). Segments of difference judgments between observers C and D were normokinesis-hypokinesis; 62.1%, hypokinesis-akinesis; 33.3%, akinesis-dyskinesis; 3.0%, and normokinesis-akinesis; 1.5%. Wall motion can be evaluated at remote institutions via the Internet.

Evaluation of left ventricular function using electrocardiographically gated myocardial SPECT with (123)I-labeled fatty acid analog.

PubMed

Nanasato, M; Ando, A; Isobe, S; Nonokawa, M; Hirayama, H; Tsuboi, N; Ito, T; Hirai, M; Yokota, M; Saito, H

2001-12-01

Electrocardiographically (ECG) gated myocardial SPECT with (99m)Tc-tetrofosmin has been used widely to assess left ventricular (LV) function. However, the accuracy of variables using ECG gated myocardial SPECT with beta-methyl-p-(123)I-iodophenylpentadecanoic acid (BMIPP) has not been well defined. Thirty-six patients (29 men, 7 women; mean age, 61.6 +/- 15.6 y) with ischemic heart disease underwent ECG gated myocardial SPECT with (123)I-BMIPP and with (99m)Tc-tetrofosmin and left ventriculography (LVG) within 1 wk. LV ejection fraction (LVEF), LV end-diastolic volume (LVEDV), and LV end-systolic volume (LVESV) were determined on gated SPECT using commercially available software for automatic data analysis. These volume-related items on LVG were calculated with an area-length method and were estimated by 2 independent observers to evaluate interobserver validity. The regional wall motion with these methods was assessed visually. LVEF was 41.1% +/- 12.5% on gated SPECT with (123)I-BMIPP, 44.5% +/- 13.1% on gated SPECT with (99m)Tc-tetrofosmin, and 46.0% +/- 12.7% on LVG. Global LV function and regional wall motion between both gated SPECT procedures had excellent correlation (LVEF, r = 0.943; LVEDV, r = 0.934; LVESV, r = 0.952; regional wall motion, kappa = 0.92). However, the correlations of global LV function and regional wall motion between each gated SPECT and LVG were significantly lower. Gated SPECT with (123)I-BMIPP showed the same interobserver validity as gated SPECT with (99m)Tc-tetrofosmin. Gated SPECT with (123)I-BMIPP provides high accuracy with regard to LV function and is sufficiently applicable for use in clinical SPECT. This technique can simultaneously reveal myocardial fatty acid metabolism and LV function, which may be useful to evaluate various cardiac diseases.

Effects of Simulated Surface Effect Ship Motions on Crew Habitability. Phase II. Volume 4. Crew Cognitive Functions, Physiological Stress, and Sleep

DTIC Science & Technology

1977-05-01

1OUM 44 rRE JamesIV FUNCION , Jn Vanlo07 James C./Miller NW147-C0_el H~fumnan Factors Research, Incorporated AE OKUI UBR Goleta, California 93017 311...a reduction in renal blood flow) and dilation of the skeletal muscle vessels produce a redistribution of the enlarged cardiac output which anticipates

Frequent Activation Delay-Induced Mechanical Dyssynchrony and Dysfunction in the Systemic Right Ventricle.

PubMed

Forsha, Daniel; Risum, Niels; Smith, P Brian; Kanter, Ronald J; Samad, Zainab; Barker, Piers; Kisslo, Joseph

2016-11-01

Patients with systemic right ventricles frequently experience progressive heart failure and conduction abnormalities leading to abnormal ventricular activation. Activation delay-induced mechanical dyssynchrony can contribute to ventricular failure and is identified by a classic strain pattern of paradoxical opposing wall motion that is an excellent predictor of response to cardiac resynchronization therapy in adults with left bundle branch block. The specific aims of this study were to compare right ventricular (RV) mechanics in an adult systemic right ventricle population versus control subjects, evaluate the feasibility of this RV strain pattern analysis, and determine the frequency of the classic pattern. Young adults (n = 25) with d-transposition of the great arteries, status post Mustard or Senning palliation (TGA-MS), were ambispectively enrolled and compared with healthy young adults (n = 30) who were prospectively enrolled. All subjects were imaged using novel three-apical view (18-segment) RV longitudinal speckle-tracking strain analysis (EchoPAC) and electrocardiographic data. Patients with TGA-MS had diminished RV global peak systolic strain compared with control subjects (-12.0 ± 4.0% vs -23.3 ± 2.3%, P < .001). Most patients with TGA-MS had intrinsic or left ventricular paced right bundle branch block. A classic pattern was present in 11 of 25 subjects (44%), but this pattern would have been missed in four of 11 based only on the RV four-chamber (six-segment) model. Only three subjects underwent cardiac resynchronization therapy. Both subjects who had the classic pattern responded to cardiac resynchronization therapy, whereas the one nonresponder did not have the classic pattern. Systemic right ventricles demonstrated decreased function and increased mechanical dyssynchrony. The classic pattern of activation delay-induced mechanical dyssynchrony was frequently seen in this TGA-MS population and associated with activation delays. This comprehensive RV approach demonstrated incremental value. Copyright © 2016 American Society of Echocardiography. Published by Elsevier Inc. All rights reserved.

A novel approach to dual excitation ratiometric optical mapping of cardiac action potentials with di-4-ANEPPS using pulsed LED excitation.

PubMed

Bachtel, Andrew D; Gray, Richard A; Stohlman, Jayna M; Bourgeois, Elliot B; Pollard, Andrew E; Rogers, Jack M

2011-07-01

We developed a new method for ratiometric optical mapping of transmembrane potential (V(m)) in cardiac preparations stained with di-4-ANEPPS. V(m)-dependent shifts of excitation and emission spectra establish two excitation bands (<481 and >481 nm) that produce fluorescence changes of opposite polarity within a single emission band (575-620 nm). The ratio of these positive and negative fluorescence signals (excitation ratiometry) increases V(m) sensitivity and removes artifacts common to both signals. We pulsed blue (450 ± 10 nm) and cyan (505 ± 15 nm) light emitting diodes (LEDs) at 375 Hz in alternating phase synchronized to a camera (750 frames-per-second). Fluorescence was bandpass filtered (585 ± 20 nm). This produced signals with upright (blue) and inverted (cyan) action potentials (APs) interleaved in sequential frames. In four whole swine hearts with motion chemically arrested, fractional fluorescence for blue, cyan, and ratio signals was 1.2 ± 0.3%, 1.2 ± 0.3%, and 2.4 ± 0.6%, respectively. Signal-to-noise ratios were 4.3 ± 1.4, 4.0 ± 1.2, and 5.8 ± 1.9, respectively. After washing out the electromechanical uncoupling agent, we characterized motion artifact by cross-correlating blue, cyan, and ratio signals with a signal with normal AP morphology. Ratiometry improved cross-correlation coefficients from 0.50 ± 0.48 to 0.81 ± 0.25, but did not cancel all motion artifacts. These findings demonstrate the feasibility of pulsed LED excitation ratiometry in myocardium. © 2011 IEEE

A Novel Approach to Dual Excitation Ratiometric Optical Mapping of Cardiac Action Potentials with Di-4-ANEPPS using Pulsed LED Excitation

PubMed Central

Bachtel, Andrew D.; Gray, Richard A.; Stohlman, Jayna M.; Bourgeois, Elliot B.; Pollard, Andrew E.

2011-01-01

We developed a new method for ratiometric optical mapping of transmembrane potential (Vm) in cardiac preparations stained with di-4-ANEPPS. Vm-dependent shifts of excitation and emission spectra establish two excitation bands (<481 and >481 nm) that produce fluorescence changes of opposite polarity within a single emission band (575–620 nm). The ratio of these positive and negative fluorescence signals (excitation ratiometry) increases Vm sensitivity and removes artifacts common to both signals. We pulsed blue (450±10 nm) and cyan (505±15 nm) light emitting diodes (LEDs) at 375 Hz in alternating phase synchronized to a camera (750 frames-per-second). Fluorescence was bandpass filtered (585±20 nm). This produced signals with upright (blue) and inverted (cyan) action potentials (APs) interleaved in sequential frames. In 4 whole swine hearts with motion chemically arrested, fractional fluorescence for blue, cyan, and ratio signals was 1.2±0.3%, 1.2±0.3%, and 2.4±0.6%, respectively. Signal-to-noise ratios were 4.3±1.4, 4.0±1.2, and 5.8±1.9, respectively. After washing out the electromechanical uncoupling agent, we characterized motion artifact by cross-correlating blue, cyan, and ratio signals with a signal with normal AP morphology. Ratiometry improved cross-correlation coefficients from 0.50±0.48 to 0.81±0.25, but did not cancel all motion artifacts. These findings demonstrate the feasibility of pulsed LED excitation ratiometry in myocardium. PMID:21536528

High-intensity focused ultrasound ablation of myocardium in vivo and instantaneous biological response.

PubMed

Zheng, Minjuan; Shentu, Weihui; Chen, Dingzhang; Sahn, David J; Zhou, Xiaodong

2014-10-01

This study aimed to evaluate the instantaneous biological response of canine myocardium in vivo to high-intensity focused ultrasound (HIFU) ablation, and thereby determine the feasibility of this method. Left ventricle myocardium HIFU ablation was performed on six dogs at four levels of HIFU energy (acoustic intensity was 3000 W/cm2 ; ablation durations were 1.2, 2.4, 3.6, and 4.8 sec, respectively). Gross lesion volumes were confirmed and assessed by tetrazolium chloride (TTC) staining, hematoxylin-eosin (HE) staining, and electron microscopy. Global cardiac function and focal wall motion were evaluated by echocardiography. Blood enzymes and cardiac troponin T (CTnT) were tested after ablation. HIFU ablation was repeated on another set of six fresh canine hearts in vitro at the same four energy levels. Focal maximum temperatures were detected both in vivo and in vitro. Different sizes of ablation via HIFU can be created in beating hearts using controlled energy emission. Focal maximum temperatures varied from 62 ± 4.8 °C to 81 ± 12.9 °C. The lesion sizes were significantly smaller in vivo than in vitro, as verified by TTC and HE staining. Focal wall motion immediately decreased after ablation (P < 0.05), although the ejection fraction (EF) and E/A ratio were unchanged (P > 0.05). Enzymes and CTnT immediately increased. HIFU can be used for the controllable ablation of myocardial tissue, with instantly increased serum markers, decreased regional wall motion, and unaffected left ventricular global function. © 2014, Wiley Periodicals, Inc.

MRI-Based Nonrigid Motion Correction in Simultaneous PET/MRI

PubMed Central

Chun, Se Young; Reese, Timothy G.; Ouyang, Jinsong; Guerin, Bastien; Catana, Ciprian; Zhu, Xuping; Alpert, Nathaniel M.; El Fakhri, Georges

2014-01-01

Respiratory and cardiac motion is the most serious limitation to whole-body PET, resulting in spatial resolution close to 1 cm. Furthermore, motion-induced inconsistencies in the attenuation measurements often lead to significant artifacts in the reconstructed images. Gating can remove motion artifacts at the cost of increased noise. This paper presents an approach to respiratory motion correction using simultaneous PET/MRI to demonstrate initial results in phantoms, rabbits, and nonhuman primates and discusses the prospects for clinical application. Methods Studies with a deformable phantom, a free-breathing primate, and rabbits implanted with radioactive beads were performed with simultaneous PET/MRI. Motion fields were estimated from concurrently acquired tagged MR images using 2 B-spline nonrigid image registration methods and incorporated into a PET list-mode ordered-subsets expectation maximization algorithm. Using the measured motion fields to transform both the emission data and the attenuation data, we could use all the coincidence data to reconstruct any phase of the respiratory cycle. We compared the resulting SNR and the channelized Hotelling observer (CHO) detection signal-to-noise ratio (SNR) in the motion-corrected reconstruction with the results obtained from standard gating and uncorrected studies. Results Motion correction virtually eliminated motion blur without reducing SNR, yielding images with SNR comparable to those obtained by gating with 5–8 times longer acquisitions in all studies. The CHO study in dynamic phantoms demonstrated a significant improvement (166%–276%) in lesion detection SNR with MRI-based motion correction as compared with gating (P < 0.001). This improvement was 43%–92% for large motion compared with lesion detection without motion correction (P < 0.001). CHO SNR in the rabbit studies confirmed these results. Conclusion Tagged MRI motion correction in simultaneous PET/MRI significantly improves lesion detection compared with respiratory gating and no motion correction while reducing radiation dose. In vivo primate and rabbit studies confirmed the improvement in PET image quality and provide the rationale for evaluation in simultaneous whole-body PET/MRI clinical studies. PMID:22743250

Diffusion MRI in the heart

PubMed Central

Mekkaoui, Choukri; Reese, Timothy G.; Jackowski, Marcel P.; Bhat, Himanshu

2015-01-01

Diffusion MRI provides unique information on the structure, organization, and integrity of the myocardium without the need for exogenous contrast agents. Diffusion MRI in the heart, however, has proven technically challenging because of the intrinsic non‐rigid deformation during the cardiac cycle, displacement of the myocardium due to respiratory motion, signal inhomogeneity within the thorax, and short transverse relaxation times. Recently developed accelerated diffusion‐weighted MR acquisition sequences combined with advanced post‐processing techniques have improved the accuracy and efficiency of diffusion MRI in the myocardium. In this review, we describe the solutions and approaches that have been developed to enable diffusion MRI of the heart in vivo, including a dual‐gated stimulated echo approach, a velocity‐ (M 1) or an acceleration‐ (M 2) compensated pulsed gradient spin echo approach, and the use of principal component analysis filtering. The structure of the myocardium and the application of these techniques in ischemic heart disease are also briefly reviewed. The advent of clinical MR systems with stronger gradients will likely facilitate the translation of cardiac diffusion MRI into clinical use. The addition of diffusion MRI to the well‐established set of cardiovascular imaging techniques should lead to new and complementary approaches for the diagnosis and evaluation of patients with heart disease. © 2015 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd. PMID:26484848

Evaluation of left ventricular wall motion and function in patients with previous myocardial infarction by three-dimensional 99mTc-HSAD multigated cardiac pool imaging.

PubMed

Yamazaki, J; Naitou, K; Ishida, S; Uno, N; Saisho, K; Munakata, T; Morishita, T; Takano, M; Yabe, Y

1997-05-01

To evaluate left ventricular (LV) wall motion stereoscopically from all directions and to calculate the LV volume by three-dimensional (3D) imaging. 99mTc-DTPA human serum albumin-multigated cardiac pool-single photon emission computed tomography (99mTc-MUGA-SPECT) was performed. A new data processing program was developed with the Application Visualization System-Medical Viewer (AVS-MV) based on images obtained from 99mTc-MUGA-SPECT. In patients with previous myocardial infarction, LV function and LV wall motion were evaluated by 3D-99mTc-MUGA imaging. The LV end-diastolic volume (LVEDV) and end-systolic volume (LVESV) were obtained from 3D-99mTc-MUGA images by the surface rendering method, and the left ventricular ejection fraction (LVEF) was calculated at thresholds of 35% (T1), 40% (T2), 45% (T3), and 50% (T4). There was a strong correlation between the LV volume calculated by 3D-99mTc-MUGA imaging at a threshold of 40% and that determined by contrast left ventriculography (LVEDV: 194.7 +/- 36.0 ml vs. 198.7 +/- 39.1 ml, r = 0.791, p < 0.001; LVESV: 91.6 +/- 44.5 ml vs. 93.3 +/- 41.3 ml, r = 0.953, p < 0.001), respectively. When compared with the LVEF data obtained by left ventriculography, significant correlations were found for 3D images reconstructed at each threshold (T1: r = 0.966; T2: r = 0.962; T3: r = 0.958; and T4: r = 0.955). In addition, when LV wall motion obtained by 3D-99mTc-MUGA imaging (LAT and LAO views) was compared with the results obtained by left ventriculography (RAO and LAO views), there was good agreement. 3D-99mTc-MUGA imaging was superior in allowing evaluation of LV wall motion in all directions and in assessment of LV function, since data acquisition and image reconstruction could be done within a short time with the three-detector imaging system and AVS-MV. This method appears to be very useful for the observation of both LV wall motion and LV function in patients with ischemic heart disease, because it is a noninvasive examination.

In vivo quantification of motion in liver parenchyma and its application in shistosomiasis tissue characterization

NASA Astrophysics Data System (ADS)

Badawi, Ahmed M.; Hashem, Ahmed M.; Youssef, Abou-Bakr M.; Abdel-Wahab, Mohamed F.

1995-03-01

Schistosomiasis is a major problem in Egypt, despite an active control program it is estimated to exist in about 1/3 of the population. Deposition of less functioning fibrous tissues in the liver is the major contributory factor to the hepatic pathology. Fibrous tissues consist of a complex array of connective matrix material and a variety of collagen isotopes. As a result of an increased stromal density (collagen content), the parenchyma became more ectogenic and less elastic (hard). In this study we investigated the effect of cardiac mechanical impulses from the heart and aorta on the kinetics of the liver parenchyma. Under conditions of controlled patient movements and suspended respiration, a 30 frame per second of 588 X 512 ultrasound images (cineloop, 32 pels per cm) are captured from an aTL ultrasound machine then digitized. The image acquisition is triggered by the R wave of the ECG of the patient. The motion that has a forced oscillation form in the liver parenchyma is quantified by tracking of small box (20 - 30 pels) in 16 directions for all the successive 30 frames. The tracking was done using block matching techniques (the max correlation between boxes in time, frequency domains, and the minimum SAD (sum absolute difference) between boxes). The motion is quantified for many regions at different positions within the liver parenchyma for 80 cases of variable degrees of schisto., cirrhotic livers, and for normal livers. The velocity of the tissue is calculated from the displacement (quantified motion), time between frames, and the scan time for the ultrasound scanner. We found that the motion in liver parenchyma is small in the order of very few millimeters, and the attenuation of the mechanical wave for one ECG cycle is higher in the schisto. and cirrhotic livers than in the normal ones. Finally quantification of motion in liver parenchyma due to cardiac impulses under controlled limb movement and respiration may be of value in the characterization of schisto. (elasticity based not scattering based). This value could be used together with the wide varieties of quantitative tissue characterization parameters for pathology differentiation and for differentiating subclasses of cirrhosis as well as the determination of the extent of bilharzial affection.

The clinical significance of perivalvular pannus in prosthetic mitral valves: Can cardiac CT be helpful?

PubMed

Chang, Suyon; Suh, Young Joo; Han, Kyunghwa; Kim, Jin Young; Kim, Young Jin; Chang, Byung-Chul; Choi, Byoung Wook

2017-12-15

The clinical significance of pannus in the prosthetic mitral valve (MV) is not well documented. To investigate the clinical significance of pannus on cardiac computed tomography (CT) in patients with a prosthetic MV. A total of 130 patients with previous MV replacement who underwent cardiac CT were retrospectively included in this study. The presence of pannus, paravalvular leak (PVL) around the prosthetic MV and limitation of motion (LOM) of the MV were analyzed using CT. Between patients with MV pannus and those without pannus, CT, echocardiographic, and redo-surgery findings were compared. The diagnostic performance of CT and transesophageal echocardiography (TEE) for the detection of MV pannus was also compared, using surgical findings as a standard reference. MV pannus was observed on cardiac CT in 32.3% of the study population. Patients with MV pannus detected on CT more commonly had LOM (28.2% vs. 15.2%) and less frequently had PVL of the prosthetic MV (16.7% vs. 25%) than patients without MV pannus (P>0.05). Prosthetic valve obstruction (PVO) due prosthetic MV pannus requiring redo-surgery was present in only five patients (11.9%). Cardiac CT detected MV pannus with sensitivity of 65.2% and specificity of 80.9% and showed better diagnostic performance than TEE (P<0.05). Prosthetic MV pannus can frequently be seen on cardiac CT. However, its clinical significance should be assessed with careful consideration, because PVO due to MV pannus is relatively uncommon, and pannus can be seen in patients without any clinical problems. Copyright © 2017 Elsevier B.V. All rights reserved.

Does the prognostic value of dobutamine stress echocardiography differ among different age groups?

PubMed

Bernheim, Alain M; Kittipovanonth, Maytinee; Takahashi, Paul Y; Gharacholou, S Michael; Scott, Christopher G; Pellikka, Patricia A

2011-04-01

Age is associated with reduced exercise capacity and greater prevalence of coronary artery disease. Whether the prognostic information obtained from dobutamine stress echocardiography (DSE), a stress test commonly used for patients unable to perform an exercise test, provides differential information based on age is not well known. We studied 6,655 consecutive patients referred for DSE. Patients were divided into 3 age groups: (1) <60 years (n = 1,389), (2) 60 to 74 years (n = 2,978), and (3) ≥75 years (n = 2,288). Mean follow-up was 5.5 ± 2.8 years. End points included all-cause mortality and cardiac events, including myocardial infarction and late (>3 months) coronary revascularization. Peak stress wall motion score index was an independent predictor of cardiac events in all age groups (<60 years: hazard ratio [HR] 1.14, P = .02; 60-74 years: HR 1.70, P < .0001; ≥75 years: HR 1.10, P = .006). In patients ≥75 years, peak wall motion score index (HR 1.10, P < .0001) and abnormal left ventricular end-systolic volume response (HR 1.25, P = .03) were independent predictors of death. In patients aged 60 to 74 years, abnormal left ventricular end-systolic volume response (HR 1.43, P = .0003) was independently related to death, whereas in patients <60 years, the echocardiographic data assessed during stress were not a predictor. Dobutamine stress echocardiography provided independent information predictive of cardiac events among all age groups and death in patients ≥60 years. However, among patients <60 years, stress-induced echocardiographic abnormalities were not independently associated with mortality. Comorbidities, which have precluded exercise testing, may be most relevant in predicting mortality in patients <60 years undergoing DSE. Copyright © 2011 Mosby, Inc. All rights reserved.

Mitral annulus motion as determined by M-mode echocardiography in normal dogs and dogs with cardiac disease.

PubMed

Schober, K E; Fuentes, V L

2001-01-01

M-mode echocardiography was used to assess apical mitral annulus motion (MAM) in 103 normal dogs and 101 dogs with cardiac disease, to obtain information on systolic left ventricular long axis function. In normal dogs, a close relationship was found between MAM and body weight (r = 0.80, P < 0.001). There was a weak correlation between MAM and heart rate (r = -0.25, P < 0.05), but no correlation between MAM and age or left ventricular shortening fraction (P > 0.05). Mean MAM (95% confidence intervals) were established for normal dogs of differing body weight, and were 0.70 cm (0.65 to 0.75) in dogs < 15 kg, 1.08 cm (1.03 to 1.13) in dogs weighing 15 to 40 kg, and 1.51 cm (1.21 to 1.81) in dogs > 40 kg. "Cut-off" values to define decreased MAM for normal dogs of differing body weight were 0.45 cm (dogs < 15 kg), 0.80 cm (dogs 15-40 kg), and 1.20 cm (dogs > 40 kg). In dogs with cardiac disease, median MAM was normal in mitral valve endocardiosis or aortic stenosis, but significantly decreased (P < 0.05) in dilated cardiomyopathy. All dogs with mitral valve endocardiosis (n = 54) or aortic stenosis (n = 26) had MAM above the above-mentioned "cut-off" values, suggesting normal or increased left ventricular longitudinal systolic shortening, whereas 81% (17/21) of dogs with dilated cardiomyopathy had MAM below the "cut-off" value, indicating decreased long axis systolic function. It is concluded that MAM may be used to evaluate systolic left ventricular long axis performance in dogs and may add useful information on global left ventricular contraction dynamics.

The prognostic value of dobutamine stress echocardiography amongst British Indian Asian and Afro-Caribbean patients: a comparison with European white patients.

PubMed

O'Driscoll, Jamie M; Rossato, Claire; Gargallo-Fernandez, Paula; Araco, Marco; Giannoglou, Dimitrios; Sharma, Sanjay; Sharma, Rajan

2015-08-06

The incidence of cardiovascular disease is considerably disparate among different racial and ethnic populations. While dobutamine stress echocardiography (DSE) has been shown to be useful in Caucasian patients, its role among ethnic minority groups remains unclear. This study aimed to investigate the prognostic importance of DSE in three ethnic groups in the UK. DSE was performed on 6231 consecutive patients. After exclusions, 5329 patients formed the study (2676 [50.2%] Indian Asian, 2219 [41.6%] European white and 434 [8.1%] Afro-Caribbean). Study outcome measures were non-fatal cardiac events (NFCE) and all-cause mortality. There were 849 (15.9%) NFCE and 1365 (25.6%) deaths over a median follow-up period of 4.6 years. In total 1174 (22%) patients had inducible myocardial ischaemia during DSE, 859 (16.1%) had fixed wall motion abnormalities and 3645 (68.4%) patients had a normal study. Ethnicity did not predict events. Among the three ethnic groups, ischaemia on DSE was associated with 2 to 2.5 times the risk of non-fatal cardiac events and 1.2 to 1.4 times the risk of all-cause mortality. Peak wall motion score index was the strongest independent predictor of non-fatal cardiac events and all-cause mortality in all groups. The C statistic for the prediction of NFCE and all-cause mortality were significantly higher when DSE parameters were added to the standard risk factors for all ethnic groups. DSE is a strong predictor of NFCE and all-cause mortality and provides predictive information beyond that provided by standard risk factors in three major racial and ethnic groups. No major differences among racial and ethnic groups in the predictive value of DSE was detected.

Effect of Ablation of Area Postrema on Frequency and Latency of Motion Sickness-Induced Emesis in the Squirrel Monkey

NASA Technical Reports Server (NTRS)

Brizzee, K. R.; Ordy, J. M.; Mehler, W. R.

1980-01-01

Twelve young adult squirrel monkeys of the Bolivian subspecies were subjected to continuous counter-clockwise horizontal rotary motion at 25 rpm, together with a sinusoidal vertical excursion of 6 in. every 2 sec (0.5 Hz). Each animal was exposed to this motion regimen for a period of 60 min once each week for three consecutive weeks. Following the third weekly motion test bilateral ablation of the Area Postrema (AP) was performed in eight of the animals by thermal cautery. Two control animals were sham-operated after the third motion test while two additional controls were given the motion tests as noted above but were not operated. The four controls were considered as a single group for statistical analyses of results of the motion tests. After a recovery period of 30 to 40 days, and at a comparable interval in the non-operated controls, each animal was again tested for motion sensitivity for three consecutive weeks. The brains of all of the animals were then fixed by left ventriculal cardiac perfusion with Bouin's fluid and processed for histological evaluation of the bilateral AP ablation in comparison with the control brains. Five of the AP-ablated animals postoperatively were completely refractory to the motion stimuli, two exhibited a decreased number of emetic responses, and one exhibited the same number of responses before and after the AP lesions. The controls exhibited no significant difference in emetic sensitivity on the second series of three weekly tests than on the first series. The results of this investigation appear to be in agreement with the observations of Wang and Chinn in the dog indicating that the integrity of the AP (CTZ) is essential to the emetic response to motion.

Nppa and Nppb act redundantly during zebrafish cardiac development to confine AVC marker expression and reduce cardiac jelly volume.

PubMed

Grassini, Daniela R; Lagendijk, Anne K; De Angelis, Jessica E; Da Silva, Jason; Jeanes, Angela; Zettler, Nicole; Bower, Neil I; Hogan, Benjamin M; Smith, Kelly A

2018-05-11

Atrial natriuretic peptide ( nppa/anf ) and brain natriuretic peptide ( nppb/bnp ) form a gene cluster with expression in the chambers of the developing heart. Despite restricted expression, a function in cardiac development has not been demonstrated by mutant analysis. This is attributed to functional redundancy however their genomic location in cis has impeded formal analysis. Using genome-editing, we generated mutants for nppa and nppb and found single mutants indistinguishable from wildtype whereas nppa / nppb double mutants display heart morphogenesis defects and pericardial oedema. Analysis of atrioventricular canal (AVC) markers show expansion of bmp4 , tbx2b, has2 and versican expression into the atrium of double mutants. This expanded expression correlates with increased extracellular matrix in the atrium. Using a biosensor for Hyaluronic acid to measure the cardiac jelly (cardiac extracellular matrix), we confirm cardiac jelly expansion in nppa / nppb double mutants. Finally, bmp4 knockdown rescues the expansion of has2 expression and cardiac jelly in double mutants. This definitively shows that nppa and nppb function redundantly during cardiac development to restrict gene expression to the AVC, preventing excessive cardiac jelly synthesis in the atrial chamber. © 2018. Published by The Company of Biologists Ltd.

[A basis for application of cardiac contractility variability in the Evaluation and assessment of exercise and fitness].

PubMed

Bu, Bin; Wang, Aihua; Han, Haijun; Xiao, Shouzhong

2010-06-01

Cardiac contractility variability (CCV) is a new concept which is introduced in the research field of cardiac contractility in recent years, that is to say, there are some disparities between cardiac contractilities when heart contracts. The changing signals of cardiac contractility contain a plenty of information on the cardiovascular function and disorder. In order to collect and analyze the message, we could quantitatively evaluate the tonicity and equilibrium of cardiac sympathetic nerve and parasympathetic nerve, and the effects of bio-molecular mechanism on the cardiovascular activities. By analyzing CCV, we could further understand the background of human being's heritage characteristics, nerve types, the adjusting mechanism, the molecular biology, and the adjustment of cardiac automatic nerve. With the development of the computing techniques, the digital signal processing method and its application in medical field, this analysis has been progressing greatly. By now, the assessment of CCV, just like the analysis of heart rate variability, is mainly via time domain and frequency domain analysis. CCV is one of the latest research fields in human cardiac signals being scarcely reported in the field of sports medicine; however, its research progresses are of important value for cardiac physiology and pathology in sports medicine and rehabilitation medicine.

Cardiovascular adaptation to extrauterine life after intrauterine growth restriction.

PubMed

Rodriguez-Guerineau, Luciana; Perez-Cruz, Miriam; Gomez Roig, María D; Cambra, Francisco J; Carretero, Juan; Prada, Fredy; Gómez, Olga; Crispi, Fátima; Bartrons, Joaquim

2018-02-01

Introduction The adaptive changes of the foetal heart in intrauterine growth restriction can persist postnatally. Data regarding its consequences for early circulatory adaptation to extrauterine life are scarce. The aim of this study was to assess cardiac morphometry and function in newborns with late-onset intrauterine growth restriction to test the hypothesis that intrauterine growth restriction causes cardiac shape and functional changes at birth. A comprehensive echocardiographic study was performed in 25 neonates with intrauterine growth restriction and 25 adequate-for-gestational-age neonates. Compared with controls, neonates with intrauterine growth restriction had more globular ventricles, lower longitudinal tricuspid annular motion, and higher left stroke volume without differences in the heart rate. Neonates with intrauterine growth restriction also showed subclinical signs of diastolic dysfunction in the tissue Doppler imaging with lower values of early (e') diastolic annular peak velocities in the septal annulus. Finally, the Tei index in the tricuspid annulus was higher in the intrauterine growth restriction group. Neonates with history of intrauterine growth restriction showed cardiac remodelling and signs of systolic and diastolic dysfunction. Overall, there was a significant tendency to worse cardiac function results in the right heart. The adaptation to extrauterine life occurred with more globular hearts, higher stroke volumes but a similar heart rate compared to adequate-for-gestational-age neonates.

Comprehensive Modeling and Visualization of Cardiac Anatomy and Physiology from CT Imaging and Computer Simulations

PubMed Central

Sun, Peng; Zhou, Haoyin; Ha, Seongmin; Hartaigh, Bríain ó; Truong, Quynh A.; Min, James K.

2016-01-01

In clinical cardiology, both anatomy and physiology are needed to diagnose cardiac pathologies. CT imaging and computer simulations provide valuable and complementary data for this purpose. However, it remains challenging to gain useful information from the large amount of high-dimensional diverse data. The current tools are not adequately integrated to visualize anatomic and physiologic data from a complete yet focused perspective. We introduce a new computer-aided diagnosis framework, which allows for comprehensive modeling and visualization of cardiac anatomy and physiology from CT imaging data and computer simulations, with a primary focus on ischemic heart disease. The following visual information is presented: (1) Anatomy from CT imaging: geometric modeling and visualization of cardiac anatomy, including four heart chambers, left and right ventricular outflow tracts, and coronary arteries; (2) Function from CT imaging: motion modeling, strain calculation, and visualization of four heart chambers; (3) Physiology from CT imaging: quantification and visualization of myocardial perfusion and contextual integration with coronary artery anatomy; (4) Physiology from computer simulation: computation and visualization of hemodynamics (e.g., coronary blood velocity, pressure, shear stress, and fluid forces on the vessel wall). Substantially, feedback from cardiologists have confirmed the practical utility of integrating these features for the purpose of computer-aided diagnosis of ischemic heart disease. PMID:26863663

Whole-body strength training with Huber Motion Lab and traditional strength training in cardiac rehabilitation: A randomized controlled study.

PubMed

Guiraud, Thibaut; Labrunée, Marc; Besnier, Florent; Sénard, Jean-Michel; Pillard, Fabien; Rivière, Daniel; Richard, Lisa; Laroche, Davy; Sanguignol, Frédéric; Pathak, Atul; Gayda, Mathieu; Gremeaux, Vincent

2017-01-01

Isometric strengthening has been rarely studied in patients with coronary heart disease (CHD), mainly because of possible potential side effects and lack of appropriate and reliable devices. We aimed to compare 2 different modes of resistance training, an isometric mode with the Huber Motion Lab (HML) and traditional strength training (TST), in CHD patients undergoing a cardiac rehabilitation program. We randomly assigned 50 patients to HML or TST. Patients underwent complete blinded evaluation before and after the rehabilitation program, including testing for cardiopulmonary exercise, maximal isometric voluntary contraction, endothelial function and body composition. After 4 weeks of training (16 sessions), the groups did not differ in body composition, anthropometric characteristics, or endothelial function. With HML, peak power output (P=0.035), maximal heart rate (P<0.01) and gain of force measured in the chest press position (P<0.02) were greater after versus before training. Both protocols appeared to be well tolerated, safe and feasible for these CHD patients. A training protocol involving 6s phases of isometric contractions with 10s of passive recovery on an HML device could be safely implemented in rehabilitation programs for patients with CHD and improve functional outcomes. Copyright © 2016. Published by Elsevier Masson SAS.

Echocardiographic Techniques of Deformation Imaging in the Evaluation of Maternal Cardiovascular System in Patients with Complicated Pregnancies.

PubMed

Visentin, Silvia; Palermo, Chiara; Camerin, Martina; Daliento, Luciano; Muraru, Denisa; Cosmi, Erich; Badano, Luigi P

2017-01-01

Cardiovascular diseases (CVD) represent the leading cause of maternal mortality and morbidity. Knowledge of CVD in women is constantly evolving and data are emerging that female-specific risk factors as complications of pregnancy are conditions associated with an increased risk for the long-term development of CVD. Echocardiography is a safe and effective imaging technique indicated in symptomatic or asymptomatic pregnant women with congenital heart diseases who require close monitoring of cardiac function. Deformation imaging is an echocardiographic technique used to assess myocardial function by measuring the actual deformation of the myocardium through the cardiac cycle. Speckle-tracking echocardiography (STE) is a two-dimensional (2D) technique which has been found to be more accurate than tissue Doppler to assess both left ventricular (LV) and right ventricular (RV) myocardial function. The use of 2D STE however might present some technical issues due to the tomographic nature of the technique and the motion in the three-dimensional space of the myocardial speckles. This has promoted the use of 3D STE to track the motion of the speckles in the 3D space. This review will focus on the clinical value of the new echocardiographic techniques of deformation imaging used to assess the maternal cardiovascular system in complicated pregnancies.

Stochastic precision analysis of 2D cardiac strain estimation in vivo

NASA Astrophysics Data System (ADS)

Bunting, E. A.; Provost, J.; Konofagou, E. E.

2014-11-01

Ultrasonic strain imaging has been applied to echocardiography and carries great potential to be used as a tool in the clinical setting. Two-dimensional (2D) strain estimation may be useful when studying the heart due to the complex, 3D deformation of the cardiac tissue. Increasing the framerate used for motion estimation, i.e. motion estimation rate (MER), has been shown to improve the precision of the strain estimation, although maintaining the spatial resolution necessary to view the entire heart structure in a single heartbeat remains challenging at high MERs. Two previously developed methods, the temporally unequispaced acquisition sequence (TUAS) and the diverging beam sequence (DBS), have been used in the past to successfully estimate in vivo axial strain at high MERs without compromising spatial resolution. In this study, a stochastic assessment of 2D strain estimation precision is performed in vivo for both sequences at varying MERs (65, 272, 544, 815 Hz for TUAS; 250, 500, 1000, 2000 Hz for DBS). 2D incremental strains were estimated during left ventricular contraction in five healthy volunteers using a normalized cross-correlation function and a least-squares strain estimator. Both sequences were shown capable of estimating 2D incremental strains in vivo. The conditional expected value of the elastographic signal-to-noise ratio (E(SNRe|ɛ)) was used to compare strain estimation precision of both sequences at multiple MERs over a wide range of clinical strain values. The results here indicate that axial strain estimation precision is much more dependent on MER than lateral strain estimation, while lateral estimation is more affected by strain magnitude. MER should be increased at least above 544 Hz to avoid suboptimal axial strain estimation. Radial and circumferential strain estimations were influenced by the axial and lateral strain in different ways. Furthermore, the TUAS and DBS were found to be of comparable precision at similar MERs.

Conformational changes of an ion-channel during gating and emerging electrophysiologic properties: Application of a computational approach to cardiac Kv7.1.

PubMed

Nekouzadeh, Ali; Rudy, Yoram

2016-01-01

Ion channels are the "building blocks" of the excitation process in excitable tissues. Despite advances in determining their molecular structure, understanding the relationship between channel protein structure and electrical excitation remains a challenge. The Kv7.1 potassium channel is an important determinant of the cardiac action potential and its adaptation to rate changes. It is subject to beta adrenergic regulation, and many mutations in the channel protein are associated with the arrhythmic long QT syndrome. In this theoretical study, we use a novel computational approach to simulate the conformational changes that Kv7.1 undergoes during activation gating and compute the resulting electrophysiologic function in terms of single-channel and macroscopic currents. We generated all possible conformations of the S4-S5 linker that couples the S3-S4 complex (voltage sensor domain, VSD) to the pore, and all associated conformations of VSD and the pore (S6). Analysis of these conformations revealed that VSD-to-pore mechanical coupling during activation gating involves outward translation of the voltage sensor, accompanied by a translation away from the pore and clockwise twist. These motions cause pore opening by moving the S4-S5 linker upward and away from the pore, providing space for the S6 tails to move away from each other. Single channel records, computed from the simulated motion trajectories during gating, have stochastic properties similar to experimentally recorded traces. Macroscopic current through an ensemble of channels displays two key properties of Kv7.1: an initial delay of activation and fast inactivation. The simulations suggest a molecular mechanism for fast inactivation; a large twist of the VSD following its outward translation results in movement of the base of the S4-S5 linker toward the pore, eliminating open pore conformations to cause inactivation. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Seismocardiography-Based Cardiac Computed Tomography Gating Using Patient-Specific Template Identification and Detection.

PubMed

Yao, Jingting; Tridandapani, Srini; Wick, Carson A; Bhatti, Pamela T

2017-01-01

To more accurately trigger cardiac computed tomography angiography (CTA) than electrocardiography (ECG) alone, a sub-system is proposed as an intermediate step toward fusing ECG with seismocardiography (SCG). Accurate prediction of quiescent phases is crucial to prospectively gating CTA, which is susceptible to cardiac motion and, thus, can affect the diagnostic quality of images. The key innovation of this sub-system is that it identifies the SCG waveform corresponding to heart sounds and determines their phases within the cardiac cycles. Furthermore, this relationship is modeled as a linear function with respect to heart rate. For this paper, B-mode echocardiography is used as the gold standard for identifying the quiescent phases. We analyzed synchronous ECG, SCG, and echocardiography data acquired from seven healthy subjects (mean age: 31; age range: 22-48; males: 4) and 11 cardiac patients (mean age: 56; age range: 31-78; males: 6). On average, the proposed algorithm was able to successfully identify 79% of the SCG waveforms in systole and 68% in diastole. The simulated results show that SCG-based prediction produced less average phase error than that of ECG. It was found that the accuracy of ECG-based gating is more susceptible to increases in heart rate variability, while SCG-based gating is susceptible to high cycle to cycle variability in morphology. This pilot work of prediction using SCG waveforms enriches the framework of a comprehensive system with multiple modalities that could potentially, in real time, improve the image quality of CTA.

The cardioprotective efficacy of TVP1022 against ischemia/reperfusion injury and cardiac remodeling in rats.

PubMed

Malka, Assaf; Ertracht, Offir; Bachner-Hinenzon, Noa; Reiter, Irina; Binah, Ofer

2016-12-01

Following acute myocardial infarction (MI), early and successful reperfusion is the most effective strategy for reducing infarct size and improving the clinical outcome. However, immediate restoration of blood flow to the ischemic zone results in myocardial damage, defined as "reperfusion-injury". Whereas we previously reported that TVP1022 (the S-isomer of rasagiline, FDA-approved anti-Parkinson drug) decreased infarct size 24 h post ischemia reperfusion (I/R) in rats, in this study we investigated the chronic cardioprotective efficacy of TVP1022 14 days post-I/R. To simulate the clinical settings of acute MI followed by reperfusion therapy, we employed a rat model of left anterior descending artery occlusion for 30 min followed by reperfusion and a follow-up for 14 days. TVP1022 was initially administered postocclusion-prereperfusion, followed by chronic daily administrations. Cardiac performance and remodeling were evaluated using customary and advanced echocardiographic methods, hemodynamic measurements by Millar Mikro-Tip ® catheter, and histopathological techniques. TVP1022 administration markedly decreased the remodeling process as illustrated by attenuation of left ventricular enlargement and cardiac hypertrophy (both at the whole heart and the cellular level). Furthermore, TVP1022 inhibited cardiac fibrosis and reduced ventricular BNP levels. Functionally, TVP1022 treatment preserved cardiac wall motion. Specifically, the echocardiographic and most of the direct hemodynamic measures were pronouncedly improved by TVP1022. Collectively, these findings indicate that TVP1022 provides prominent cardioprotection against I/R injury and post-MI remodeling in this I/R model.

Three-dimensional cardiac architecture determined by two-photon microtomy

NASA Astrophysics Data System (ADS)

Huang, Hayden; MacGillivray, Catherine; Kwon, Hyuk-Sang; Lammerding, Jan; Robbins, Jeffrey; Lee, Richard T.; So, Peter

2009-07-01

Cardiac architecture is inherently three-dimensional, yet most characterizations rely on two-dimensional histological slices or dissociated cells, which remove the native geometry of the heart. We previously developed a method for labeling intact heart sections without dissociation and imaging large volumes while preserving their three-dimensional structure. We further refine this method to permit quantitative analysis of imaged sections. After data acquisition, these sections are assembled using image-processing tools, and qualitative and quantitative information is extracted. By examining the reconstructed cardiac blocks, one can observe end-to-end adjacent cardiac myocytes (cardiac strands) changing cross-sectional geometries, merging and separating from other strands. Quantitatively, representative cross-sectional areas typically used for determining hypertrophy omit the three-dimensional component; we show that taking orientation into account can significantly alter the analysis. Using fast-Fourier transform analysis, we analyze the gross organization of cardiac strands in three dimensions. By characterizing cardiac structure in three dimensions, we are able to determine that the α crystallin mutation leads to hypertrophy with cross-sectional area increases, but not necessarily via changes in fiber orientation distribution.

Vascular parameters continue to decrease post-exposure with simultaneous, but not individual exposure to BPA and hypoxia in zebrafish larvae.

PubMed

Cypher, Alysha D; Fetterman, Bryce; Bagatto, Brian

2018-04-01

How fish respond to hypoxia, a common stressor, can be altered by simultaneous exposure to pollutants like bisphenol A (BPA), a plasticizer. BPA is cardiotoxic and interferes with the hypoxia inducible factor pathway (HIF-1α), therefore disrupting the hypoxic response. Co-exposure to hypoxia and BPA also causes severe bradycardia and reduced cardiac output in zebrafish larvae. The purpose of this work was to determine how the cardiovascular effects of co-exposure vary with BPA concentration and persist beyond exposure. Zebrafish embryos were exposed to 0, 0.01, 0.1, 1, and 100 μg/L of BPA during normoxia (>6.0 mg/L O 2 ) and hypoxia (2.0 ± 0.5 mg/L O 2 ) between 1 h post fertilization (hpf) and late hatching (72-96 hpf). Heart rate, cardiac output, and red blood cell (RBC) velocity were determined through video microscopy and digital motion analysis at late hatching and 10 days post fertilization (dpf), several days post exposure. In comparison to the hypoxic control, RBC velocity was 25% lower with 0.01 μg/L BPA and hypoxia at late hatching. At 10 dpf, the difference in RBC velocity between these treatments doubled, despite several days of recovery. This coincided with a 24% thinner outer diameter for caudal vein but no effect on cardiac or developmental parameters. Statistical interactions between BPA and oxygen concentration were found for arterial RBC velocity at both ages. Because the co-occurrence of both stressors is extremely common, it would be beneficial to understand how BPA and hypoxia interact to affect cardiovascular function during and after exposure. Copyright © 2018 Elsevier Inc. All rights reserved.

[Myocardial infarction. New universal definition and its implementation in clinical practice].

PubMed

Vafaie, M; Katus, H A

2013-12-01

The third version of the Universal Definition of Myocardial Infarction (MI) was published in 2012. The diagnosis of acute myocardial infarction (AMI) should only be made in a clinical setting consistent with acute myocardial ischaemia when evidence of myocardial necrosis is present. The diagnostic criteria for MI are fulfilled when a rise and/or fall of cardiac biomarkers (preferentially troponins) occurs with at least one value above the 99th percentile of the upper reference limit. In addition, there should be symptoms of ischaemia, new changes in electrocardiogram (ECG), imaging evidence of a new loss of viable myocardium or new regional wall motion abnormality, or the identification of an intracoronary thrombus by angiography or autopsy. This revised definition updates previous versions by including changes to diagnostic ECG criteria, placing a higher emphasis on cardiac imaging, modifying the criteria for subtypes of MI and implementing high sensitivity cardiac troponin (cTn) assays. A guideline-based algorithm for management of patients with suspected acute coronary syndrome allowing "early rule-in" and "rule-out" of non-STEMI with high sensitivity cTn assays is also presented.

Left ventricular function in Friedreich's ataxia. An echocardiographic study.

PubMed Central

Sutton, M G; Olukotun, A Y; Tajik, A J; Lovett, J L; Giuliani, E R

1980-01-01

Left ventricular function was assessed in seven patients with Friedreich's ataxia using computer-assisted analysis of the left ventricular echocardiograms and compared with those of 45 normal children matched for age and sex. The left ventricle in Friedreich's ataxia was symmetrically hypertrophied, cavity dimension was normal or small, and septal motion and peak velocity of circumferential shortening were normal in all patients. In diastole the duration of rapid filling was normal, peak rate of increase in left ventricular dimension was reduced in two patients, mitral valve opening was delayed with respect to minimum cavity dimension in seven, and there were significantly greater than normal increases in left ventricular dimension during the isovolumic period to mitral valve opening in seven, indicating abnormal and incoordinate relaxation. Peak rates of posterior wall systolic thickening and diastolic thinning were reduced in four and six patients, respectively, whereas peak rates of septal systolic thickening and diastolic thinning were reduced in one and four, respectively, suggesting a disproportionately greater impairment of the posterior wall than of septal function. The absence of asymmetric septal hypertrophy and mid-systolic closure of the aortic valve, the presence of normal septal motion, and the greater reduction in posterior wall than in septal dynamics are inconsistent with previous ideas that the heart disease of Friedreich's ataxia is identical to hypertrophic cardiomyopathy. Computer-assisted analysis of echocardiograms permits recognition of heart disease in Friedreich's ataxia before the onset of cardiac symptoms or development of clinical signs of heart disease. Images PMID:7426188

Ultra-Wideband Sensors for Improved Magnetic Resonance Imaging, Cardiovascular Monitoring and Tumour Diagnostics

PubMed Central

Thiel, Florian; Kosch, Olaf; Seifert, Frank

2010-01-01

The specific advantages of ultra-wideband electromagnetic remote sensing (UWB radar) make it a particularly attractive technique for biomedical applications. We partially review our activities in utilizing this novel approach for the benefit of high and ultra-high field magnetic resonance imaging (MRI) and other applications, e.g., for intensive care medicine and biomedical research. We could show that our approach is beneficial for applications like motion tracking for high resolution brain imaging due to the non-contact acquisition of involuntary head motions with high spatial resolution, navigation for cardiac MRI due to our interpretation of the detected physiological mechanical contraction of the heart muscle and for MR safety, since we have investigated the influence of high static magnetic fields on myocardial mechanics. From our findings we could conclude, that UWB radar can serve as a navigator technique for high and ultra-high field magnetic resonance imaging and can be beneficial preserving the high resolution capability of this imaging modality. Furthermore it can potentially be used to support standard ECG analysis by complementary information where sole ECG analysis fails. Further analytical investigations have proven the feasibility of this method for intracranial displacements detection and the rendition of a tumour’s contrast agent based perfusion dynamic. Beside these analytical approaches we have carried out FDTD simulations of a complex arrangement mimicking the illumination of a human torso model incorporating the geometry of the antennas applied. PMID:22163498

Cardiac robotics: a review and St. Mary's experience.

PubMed

Deeba, S; Aggarwal, R; Sains, P; Martin, S; Athanasiou, T; Casula, R; Darzi, A

2006-03-01

The introduction of the laparoscope led to the progress of surgery to a new era, where surgeries that were deemed major are now being performed through keyhole incisions with comparable outcomes to open surgery. However, with this new technique rose several problems like inaccurate depth perception, diminished tactile feedback, need for experienced assistance, and reduction in degrees of motion of the surgeons hands all of which inspired surgeons and engineers to look for mechanical tools to help in reducing these problems. Henceforth; came the application of robotics in surgery. A PubMed and Medline search was performed on cardiac robotic surgery and its applications in mitral valve repair and coronary artery surgery. A total of twenty one articles were picked that allude to the subject. A history of robotic surgery was outlined followed by applications of robotic manipulation in cardiac surgery was narrated. A quick overview of this technology in telemedicine was then outlined followed by future prospects of this technology in surgery was contemplated. The experience of the group from St. Mary's Hospital, London in this field was outlined. During the period of 4 years a total of 102 cases of robotic cardiac surgery were performed. The mean length of hospital stay was 3.1 days with a standard deviation of 1.4 days and the morbidity of the series explained. There was no mortality. Early studies have shown that minimally invasive cardiac surgery is feasible and yields results similar to conventional cardiac surgery, yet it is more technically demanding on the surgeon. As advantageous as this new modality is, further multicenter studies are needed to prove its efficacy. Copyright 2006 John Wiley & Sons, Ltd.

Endogenous circadian rhythm in human motor activity uncoupled from circadian influences on cardiac dynamics

PubMed Central

Ivanov, Plamen Ch.; Hu, Kun; Hilton, Michael F.; Shea, Steven A.; Stanley, H. Eugene

2007-01-01

The endogenous circadian pacemaker influences key physiologic functions, such as body temperature and heart rate, and is normally synchronized with the sleep/wake cycle. Epidemiological studies demonstrate a 24-h pattern in adverse cardiovascular events with a peak at ≈10 a.m. It is unknown whether this pattern in cardiac risk is caused by a day/night pattern of behaviors, including activity level and/or influences from the internal circadian pacemaker. We recently found that a scaling index of cardiac vulnerability has an endogenous circadian peak at the circadian phase corresponding to ≈10 a.m., which conceivably could contribute to the morning peak in cardiac risk. Here, we test whether this endogenous circadian influence on cardiac dynamics is caused by circadian-mediated changes in motor activity or whether activity and heart rate dynamics are decoupled across the circadian cycle. We analyze high-frequency recordings of motion from young healthy subjects during two complementary protocols that decouple the sleep/wake cycle from the circadian cycle while controlling scheduled behaviors. We find that static activity properties (mean and standard deviation) exhibit significant circadian rhythms with a peak at the circadian phase corresponding to 5–9 p.m. (≈9 h later than the peak in the scale-invariant index of heartbeat fluctuations). In contrast, dynamic characteristics of the temporal scale-invariant organization of activity fluctuations (long-range correlations) do not exhibit a circadian rhythm. These findings suggest that endogenous circadian-mediated activity variations are not responsible for the endogenous circadian rhythm in the scale-invariant structure of heartbeat fluctuations and likely do not contribute to the increase in cardiac risk at ≈10 a.m. PMID:18093917

Endogenous circadian rhythm in human motor activity uncoupled from circadian influences on cardiac dynamics.

PubMed

Ivanov, Plamen Ch; Hu, Kun; Hilton, Michael F; Shea, Steven A; Stanley, H Eugene

2007-12-26

The endogenous circadian pacemaker influences key physiologic functions, such as body temperature and heart rate, and is normally synchronized with the sleep/wake cycle. Epidemiological studies demonstrate a 24-h pattern in adverse cardiovascular events with a peak at approximately 10 a.m. It is unknown whether this pattern in cardiac risk is caused by a day/night pattern of behaviors, including activity level and/or influences from the internal circadian pacemaker. We recently found that a scaling index of cardiac vulnerability has an endogenous circadian peak at the circadian phase corresponding to approximately 10 a.m., which conceivably could contribute to the morning peak in cardiac risk. Here, we test whether this endogenous circadian influence on cardiac dynamics is caused by circadian-mediated changes in motor activity or whether activity and heart rate dynamics are decoupled across the circadian cycle. We analyze high-frequency recordings of motion from young healthy subjects during two complementary protocols that decouple the sleep/wake cycle from the circadian cycle while controlling scheduled behaviors. We find that static activity properties (mean and standard deviation) exhibit significant circadian rhythms with a peak at the circadian phase corresponding to 5-9 p.m. ( approximately 9 h later than the peak in the scale-invariant index of heartbeat fluctuations). In contrast, dynamic characteristics of the temporal scale-invariant organization of activity fluctuations (long-range correlations) do not exhibit a circadian rhythm. These findings suggest that endogenous circadian-mediated activity variations are not responsible for the endogenous circadian rhythm in the scale-invariant structure of heartbeat fluctuations and likely do not contribute to the increase in cardiac risk at approximately 10 a.m.

Detecting Regional Myocardial Abnormalities in Patients With Wolff-Parkinson-White Syndrome With the Use of ECG-Gated Cardiac MDCT.

PubMed

Lee, Hye-Jeong; Uhm, Jae-Sun; Joung, Boyoung; Hong, Yoo Jin; Hur, Jin; Choi, Byoung Wook; Kim, Young Jin

2016-04-01

Myocardial dyskinesia caused by the accessory pathway and related reversible heart failure have been well documented in echocardiographic studies of pediatric patients with Wolff-Parkinson-White (WPW) syndrome. However, the long-term effects of dyskinesia on the myocardium of adult patients have not been studied in depth. The goal of the present study was to evaluate regional myocardial abnormalities on cardiac CT examinations of adult patients with WPW syndrome. Of 74 patients with WPW syndrome who underwent cardiac CT from January 2006 through December 2013, 58 patients (mean [± SD] age, 52.2 ± 12.7 years), 36 (62.1%) of whom were men, were included in the study after the presence of combined cardiac disease was excluded. Two observers blindly evaluated myocardial thickness and attenuation on cardiac CT scans. On the basis of CT findings, patients were classified as having either normal or abnormal findings. We compared the two groups for other clinical findings, including observations from ECG, echocardiography, and electrophysiologic study. Of the 58 patients studied, 16 patients (27.6%) were found to have myocardial abnormalities (i.e., abnormal wall thinning with or without low attenuation). All abnormal findings corresponded with the location of the accessory pathway. Patients with abnormal findings had statistically significantly decreased left ventricular function, compared with patients with normal findings (p < 0.001). The frequency of regional wall motion abnormality was statistically significantly higher in patients with abnormal findings (p = 0.043). However, echocardiography documented structurally normal hearts in all patients. A relatively high frequency (27.6%) of regional myocardial abnormalities was observed on the cardiac CT examinations of adult patients with WPW syndrome. These abnormal findings might reflect the long-term effects of dyskinesia, suggesting irreversible myocardial injury that ultimately causes left ventricular dysfunction.

Gaze-contingent control for minimally invasive robotic surgery.

PubMed

Mylonas, George P; Darzi, Ara; Yang, Guang Zhong

2006-09-01

Recovering tissue depth and deformation during robotically assisted minimally invasive procedures is an important step towards motion compensation, stabilization and co-registration with preoperative data. This work demonstrates that eye gaze derived from binocular eye tracking can be effectively used to recover 3D motion and deformation of the soft tissue. A binocular eye-tracking device was integrated into the stereoscopic surgical console. After calibration, the 3D fixation point of the participating subjects could be accurately resolved in real time. A CT-scanned phantom heart model was used to demonstrate the accuracy of gaze-contingent depth extraction and motion stabilization of the soft tissue. The dynamic response of the oculomotor system was assessed with the proposed framework by using autoregressive modeling techniques. In vivo data were also used to perform gaze-contingent decoupling of cardiac and respiratory motion. Depth reconstruction, deformation tracking, and motion stabilization of the soft tissue were possible with binocular eye tracking. The dynamic response of the oculomotor system was able to cope with frequencies likely to occur under most routine minimally invasive surgical operations. The proposed framework presents a novel approach towards the tight integration of a human and a surgical robot where interaction in response to sensing is required to be under the control of the operating surgeon.

Magnetic resonance imaging in interventional therapy of patients with acute myocardial infarction prior to and after treatment

PubMed Central

Li, Yuzhou; Li, Chunrong; Jin, Hongrui; Huang, Wenqi

2016-01-01

The aim of the study was to investigate the cardiac magnetic resonance (CMR) imaging in interventional therapy of patients with acute myocardial infarction prior to and after treatment. Fifty-six cases of AMI patients with elective treatment by percutaneous coronary intervention (PCI) were continuously selected. Patients with an incidence of 7–10 days were treated with CMR and echocardiography to evaluate the quality of myocardial infarction, visual score method (VSM), wall motion score abnormality, left ventricular end-diastolic diameter (LVEDD), left ventricular end-systolic diameter (LVESD) and left ventricular ejection fraction (LVEF). Patients with an incidence of 10–14 days were treated with PCI, and CMR and echocardiography were evaluated after 6 months, after which the occurrence of major adverse cardiac events (MACE) were compared. The infarction quality, VSM score and wall motion abnormality (WMA) score were significantly reduced following surgery, and the difference was statistically significant (P<0.05). Ultrasound evaluation of LVEDD, LVESD, and LVEF prior to and after surgery was compared, and the difference was not statistically significant (P>0.05). Evaluation of the magnetic resonance imaging (MRI) in LVEDD prior to surgery was increased compared with that of the ultrasound in LVEDD, whereas MRI in LVESD and LVEF was decreased compared to that of the ultrasound obtained for LVESD and LVEF. Additionally, postoperative LVEDD was reduced compared with preoperative LVEDD, whereas LVEF was increased, and the difference was statistically significant (P<0.05). However, the evaluation of LVESD using the two methods exhibited no significant change. MACE occurred in 7 (12.5%) of 56 cases. The infarction quality of patients in the MACE group following surgery indicated that VSM and WMA scores were significantly higher than the group without MACE, while LVEF was lower than the MACE group following surgery, and the difference was statistically significant (P<0.05), albeit the ultrasound results of LVEF indicated no difference. In conclusion, CMR evaluation of AMI patients with elective PCI treatment in myocardial remodeling and cardiac function were more sensitive and accurate than with cardiac ultrasound. PMID:27588093

Temporally resolved electrocardiogram-triggered diffusion-weighted imaging of the human kidney: correlation between intravoxel incoherent motion parameters and renal blood flow at different time points of the cardiac cycle.

PubMed

Wittsack, Hans-Jörg; Lanzman, Rotem S; Quentin, Michael; Kuhlemann, Julia; Klasen, Janina; Pentang, Gael; Riegger, Caroline; Antoch, Gerald; Blondin, Dirk

2012-04-01

To evaluate the influence of pulsatile blood flow on apparent diffusion coefficients (ADC) and the fraction of pseudodiffusion (F(P)) in the human kidney. The kidneys of 6 healthy volunteers were examined by a 3-T magnetic resonance scanner. Electrocardiogram (ECG)-gated and respiratory-triggered diffusion-weighted imaging (DWI) and phase-contrast flow measurements were performed. Flow imaging of renal arteries was carried out to quantify the dependence of renal blood flow on the cardiac cycle. ECG-triggered DWI was acquired in the coronal plane with 16 b values in the range of 0 s/mm(2) and 750 s/mm(2) at the time of minimum (MIN) (20 milliseconds after R wave) and maximum renal blood flow (MAX) (197 ± 24 milliseconds after R wave). The diffusion coefficients were calculated using the monoexponential approach as well as the biexponential intravoxel incoherent motion model and correlated to phase-contrast flow measurements. Flow imaging showed pulsatile renal blood flow depending on the cardiac cycle. The mean flow velocity at MIN was 45 cm/s as compared with 61 cm/s at MAX. F(p) at MIN (0.29) was significantly lower than at MAX (0.40) (P = 0.001). Similarly, ADC(mono), derived from the monoexponential model, also showed a significant difference (P < 0.001) between MIN (ADC(mono) = 2.14 ± 0.08 × 10(-3) mm(2)/s) and MAX (ADC(mono) = 2.37 ± 0.04 × 10(-3) mm(2)/s). The correlation between renal blood flow and F(p) (r = 0.85) as well as ADC(mono) (r = 0.67) was statistically significant. Temporally resolved ECG-gated DWI enables for the determination of the diffusion coefficients at different time points of the cardiac cycle. ADC(mono) and FP vary significantly among acquisitions at minimum (diastole) and maximum (systole) renal blood flow. Temporally resolved ECG-gated DWI might therefore serve as a novel technique for the assessment of pulsatility in the human kidney.

Validation of an image registration and segmentation method to measure stent graft motion on ECG-gated CT using a physical dynamic stent graft model

NASA Astrophysics Data System (ADS)

Koenrades, Maaike A.; Struijs, Ella M.; Klein, Almar; Kuipers, Henny; Geelkerken, Robert H.; Slump, Cornelis H.

2017-03-01

The application of endovascular aortic aneurysm repair has expanded over the last decade. However, the long-term performance of stent grafts, in particular durable fixation and sealing to the aortic wall, remains the main concern of this treatment. The sealing and fixation are challenged at every heartbeat due to downward and radial pulsatile forces. Yet knowledge on cardiac-induced dynamics of implanted stent grafts is sparse, as it is not measured in routine clinical follow-up. Such knowledge is particularly relevant to perform fatigue tests, to predict failure in the individual patient and to improve stent graft designs. Using a physical dynamic stent graft model in an anthropomorphic phantom, we have evaluated the performance of our previously proposed segmentation and registration algorithm to detect periodic motion of stent grafts on ECG-gated (3D+t) CT data. Abdominal aortic motion profiles were simulated in two series of Gaussian based patterns with different amplitudes and frequencies. Experiments were performed on a 64-slice CT scanner with a helical scan protocol and retrospective gating. Motion patterns as estimated by our algorithm were compared to motion patterns obtained from optical camera recordings of the physical stent graft model in motion. Absolute errors of the patterns' amplitude were smaller than 0.28 mm. Even the motion pattern with an amplitude of 0.23 mm was measured, although the amplitude of motion was overestimated by the algorithm with 43%. We conclude that the algorithm performs well for measurement of stent graft motion in the mm and sub-mm range. This ultimately is expected to aid in patient-specific risk assessment and improving stent graft designs.

Reduction of irregular breathing artifacts in respiration-correlated CT images using a respiratory motion model.

PubMed

Hertanto, Agung; Zhang, Qinghui; Hu, Yu-Chi; Dzyubak, Oleksandr; Rimner, Andreas; Mageras, Gig S

2012-06-01

Respiration-correlated CT (RCCT) images produced with commonly used phase-based sorting of CT slices often exhibit discontinuity artifacts between CT slices, caused by cycle-to-cycle amplitude variations in respiration. Sorting based on the displacement of the respiratory signal yields slices at more consistent respiratory motion states and hence reduces artifacts, but missing image data (gaps) may occur. The authors report on the application of a respiratory motion model to produce an RCCT image set with reduced artifacts and without missing data. Input data consist of CT slices from a cine CT scan acquired while recording respiration by monitoring abdominal displacement. The model-based generation of RCCT images consists of four processing steps: (1) displacement-based sorting of CT slices to form volume images at 10 motion states over the cycle; (2) selection of a reference image without gaps and deformable registration between the reference image and each of the remaining images; (3) generation of the motion model by applying a principal component analysis to establish a relationship between displacement field and respiration signal at each motion state; (4) application of the motion model to deform the reference image into images at the 9 other motion states. Deformable image registration uses a modified fast free-form algorithm that excludes zero-intensity voxels, caused by missing data, from the image similarity term in the minimization function. In each iteration of the minimization, the displacement field in the gap regions is linearly interpolated from nearest neighbor nonzero intensity slices. Evaluation of the model-based RCCT examines three types of image sets: cine scans of a physical phantom programmed to move according to a patient respiratory signal, NURBS-based cardiac torso (NCAT) software phantom, and patient thoracic scans. Comparison in physical motion phantom shows that object distortion caused by variable motion amplitude in phase-based sorting is visibly reduced with model-based RCCT. Comparison of model-based RCCT to original NCAT images as ground truth shows best agreement at motion states whose displacement-sorted images have no missing slices, with mean and maximum discrepancies in lung of 1 and 3 mm, respectively. Larger discrepancies correlate with motion states having a larger number of missing slices in the displacement-sorted images. Artifacts in patient images at different motion states are also reduced. Comparison with displacement-sorted patient images as a ground truth shows that the model-based images closely reproduce the ground truth geometry at different motion states. Results in phantom and patient images indicate that the proposed method can produce RCCT image sets with reduced artifacts relative to phase-sorted images, without the gaps inherent in displacement-sorted images. The method requires a reference image at one motion state that has no missing data. Highly irregular breathing patterns can affect the method's performance, by introducing artifacts in the reference image (although reduced relative to phase-sorted images), or in decreased accuracy in the image prediction of motion states containing large regions of missing data. © 2012 American Association of Physicists in Medicine.

Free-breathing whole-heart 3D cine magnetic resonance imaging with prospective respiratory motion compensation.

PubMed

Moghari, Mehdi H; Barthur, Ashita; Amaral, Maria E; Geva, Tal; Powell, Andrew J

2018-07-01

To develop and validate a new prospective respiratory motion compensation algorithm for free-breathing whole-heart 3D cine steady-state free precession (SSFP) imaging. In a 3D cine SSFP sequence, 4 excitations per cardiac cycle are re-purposed to prospectively track heart position. Specifically, their 1D image is reconstructed and routed into the scanner's standard diaphragmatic navigator processing system. If all 4 signals are in end-expiration, cine image data from the entire cardiac cycle is accepted for image reconstruction. Prospective validation was carried out in patients (N = 17) by comparing in each a conventional breath-hold 2D cine ventricular short-axis stack and a free-breathing whole-heart 3D cine data set. All 3D cine SSFP acquisitions were successful and the mean scan time was 5.9 ± 2.7 min. Left and right ventricular end-diastolic, end-systolic, and stroke volumes by 3D cine SSFP were all larger than those from 2D cine SSFP. This bias was < 6% except for right ventricular end-systolic volume that was 12%. The 3D cine images had a lower ventricular blood-to-myocardium contrast ratio, contrast-to-noise ratio, mass, and subjective quality score. The novel prospective respiratory motion compensation method for 3D cine SSFP imaging was robust and efficient and yielded slightly larger ventricular volumes and lower mass compared to breath-hold 2D cine imaging. Magn Reson Med 80:181-189, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

CameraHRV: robust measurement of heart rate variability using a camera

NASA Astrophysics Data System (ADS)

Pai, Amruta; Veeraraghavan, Ashok; Sabharwal, Ashutosh

2018-02-01

The inter-beat-interval (time period of the cardiac cycle) changes slightly for every heartbeat; this variation is measured as Heart Rate Variability (HRV). HRV is presumed to occur due to interactions between the parasym- pathetic and sympathetic nervous system. Therefore, it is sometimes used as an indicator of the stress level of an individual. HRV also reveals some clinical information about cardiac health. Currently, HRV is accurately measured using contact devices such as a pulse oximeter. However, recent research in the field of non-contact imaging Photoplethysmography (iPPG) has made vital sign measurements using just the video recording of any exposed skin (such as a person's face) possible. The current signal processing methods for extracting HRV using peak detection perform well for contact-based systems but have poor performance for the iPPG signals. The main reason for this poor performance is the fact that current methods are sensitive to large noise sources which are often present in iPPG data. Further, current methods are not robust to motion artifacts that are common in iPPG systems. We developed a new algorithm, CameraHRV, for robustly extracting HRV even in low SNR such as is common with iPPG recordings. CameraHRV combined spatial combination and frequency demodulation to obtain HRV from the instantaneous frequency of the iPPG signal. CameraHRV outperforms other current methods of HRV estimation. Ground truth data was obtained from FDA-approved pulse oximeter for validation purposes. CameraHRV on iPPG data showed an error of 6 milliseconds for low motion and varying skin tone scenarios. The improvement in error was 14%. In case of high motion scenarios like reading, watching and talking, the error was 10 milliseconds.

Effect of thoracic epidural anesthesia combined with general anesthesia on segmental wall motion assessed by transesophageal echocardiography.

PubMed

Saada, M; Catoire, P; Bonnet, F; Delaunay, L; Gormezano, G; Macquin-Mavier, I; Brun, P

1992-09-01

Patients scheduled for vascular surgery are considered at risk for perioperative cardiac complications. Choice of anesthetic in such patients is guided by a desire not to adversely affect myocardial function. On the basis of data from laboratory studies, thoracic epidural anesthesia (TEA) has been advocated to prevent myocardial ischemia. The aim of this study was to assess whether TEA combined with general anesthesia has any effect on segmental wall motion (SWM) monitored by transesophageal echocardiography in these patients. Patients received alfentanil, midazolam, vecuronium, and 50% N2O in oxygen, and ventilation was controlled after orotracheal intubation; 12.5 mL of 2% lidocaine HCl was injected through an epidural catheter placed at T6-7 or T7-8. Hemodynamic measurements and transesophageal echocardiographic recordings were obtained before and 10, 20, 30, 40, and 60 min after lidocaine injection. Segmental wall motion was graded a posteriori by two independent experts on a predetermined scale (from 1 = normal to 5 = dyskinesia). A decrease greater than or equal to 2 grades was considered an SWM abnormality indicative of ischemia. Thoracic epidural anesthesia induced a decrease in systemic arterial blood pressure, heart rate, and cardiac index. The SWM score decreased slightly from 1.34 +/- 0.68 to 1.27 +/- 0.64 (mean +/- SD) (at 10 and 20 min, respectively) (P less than 0.05). Patients were a posteriori analyzed according to whether they had documented coronary artery disease or not. The SWM score before TEA was significantly higher in patients with documented coronary artery disease (1.51 +/- 0.88 vs 1.17 +/- 0.51, respectively; P less than 0.05) and did not change significantly after TEA.(ABSTRACT TRUNCATED AT 250 WORDS)

2-D Versus 3-D Cross-Correlation-Based Radial and Circumferential Strain Estimation Using Multiplane 2-D Ultrafast Ultrasound in a 3-D Atherosclerotic Carotid Artery Model.

PubMed

Fekkes, Stein; Swillens, Abigail E S; Hansen, Hendrik H G; Saris, Anne E C M; Nillesen, Maartje M; Iannaccone, Francesco; Segers, Patrick; de Korte, Chris L

2016-10-01

Three-dimensional (3-D) strain estimation might improve the detection and localization of high strain regions in the carotid artery (CA) for identification of vulnerable plaques. This paper compares 2-D versus 3-D displacement estimation in terms of radial and circumferential strain using simulated ultrasound (US) images of a patient-specific 3-D atherosclerotic CA model at the bifurcation embedded in surrounding tissue generated with ABAQUS software. Global longitudinal motion was superimposed to the model based on the literature data. A Philips L11-3 linear array transducer was simulated, which transmitted plane waves at three alternating angles at a pulse repetition rate of 10 kHz. Interframe (IF) radio-frequency US data were simulated in Field II for 191 equally spaced longitudinal positions of the internal CA. Accumulated radial and circumferential displacements were estimated using tracking of the IF displacements estimated by a two-step normalized cross-correlation method and displacement compounding. Least-squares strain estimation was performed to determine accumulated radial and circumferential strain. The performance of the 2-D and 3-D methods was compared by calculating the root-mean-squared error of the estimated strains with respect to the reference strains obtained from the model. More accurate strain images were obtained using the 3-D displacement estimation for the entire cardiac cycle. The 3-D technique clearly outperformed the 2-D technique in phases with high IF longitudinal motion. In fact, the large IF longitudinal motion rendered it impossible to accurately track the tissue and cumulate strains over the entire cardiac cycle with the 2-D technique.

Sliding to predict: vision-based beating heart motion estimation by modeling temporal interactions.

PubMed

Aviles-Rivero, Angelica I; Alsaleh, Samar M; Casals, Alicia

2018-03-01

Technical advancements have been part of modern medical solutions as they promote better surgical alternatives that serve to the benefit of patients. Particularly with cardiovascular surgeries, robotic surgical systems enable surgeons to perform delicate procedures on a beating heart, avoiding the complications of cardiac arrest. This advantage comes with the price of having to deal with a dynamic target which presents technical challenges for the surgical system. In this work, we propose a solution for cardiac motion estimation. Our estimation approach uses a variational framework that guarantees preservation of the complex anatomy of the heart. An advantage of our approach is that it takes into account different disturbances, such as specular reflections and occlusion events. This is achieved by performing a preprocessing step that eliminates the specular highlights and a predicting step, based on a conditional restricted Boltzmann machine, that recovers missing information caused by partial occlusions. We carried out exhaustive experimentations on two datasets, one from a phantom and the other from an in vivo procedure. The results show that our visual approach reaches an average minima in the order of magnitude of [Formula: see text] while preserving the heart's anatomical structure and providing stable values for the Jacobian determinant ranging from 0.917 to 1.015. We also show that our specular elimination approach reaches an accuracy of 99% compared to a ground truth. In terms of prediction, our approach compared favorably against two well-known predictors, NARX and EKF, giving the lowest average RMSE of 0.071. Our approach avoids the risks of using mechanical stabilizers and can also be effective for acquiring the motion of organs other than the heart, such as the lung or other deformable objects.

XCAT/DRASIM: a realistic CT/human-model simulation package

NASA Astrophysics Data System (ADS)

Fung, George S. K.; Stierstorfer, Karl; Segars, W. Paul; Taguchi, Katsuyuki; Flohr, Thomas G.; Tsui, Benjamin M. W.

2011-03-01

The aim of this research is to develop a complete CT/human-model simulation package by integrating the 4D eXtended CArdiac-Torso (XCAT) phantom, a computer generated NURBS surface based phantom that provides a realistic model of human anatomy and respiratory and cardiac motions, and the DRASIM (Siemens Healthcare) CT-data simulation program. Unlike other CT simulation tools which are based on simple mathematical primitives or voxelized phantoms, this new simulation package has the advantages of utilizing a realistic model of human anatomy and physiological motions without voxelization and with accurate modeling of the characteristics of clinical Siemens CT systems. First, we incorporated the 4D XCAT anatomy and motion models into DRASIM by implementing a new library which consists of functions to read-in the NURBS surfaces of anatomical objects and their overlapping order and material properties in the XCAT phantom. Second, we incorporated an efficient ray-tracing algorithm for line integral calculation in DRASIM by computing the intersection points of the rays cast from the x-ray source to the detector elements through the NURBS surfaces of the multiple XCAT anatomical objects along the ray paths. Third, we evaluated the integrated simulation package by performing a number of sample simulations of multiple x-ray projections from different views followed by image reconstruction. The initial simulation results were found to be promising by qualitative evaluation. In conclusion, we have developed a unique CT/human-model simulation package which has great potential as a tool in the design and optimization of CT scanners, and the development of scanning protocols and image reconstruction methods for improving CT image quality and reducing radiation dose.

High-pitch Helical Dual-source Computed Tomographic Pulmonary Angiography: Comparing Image Quality in Inspiratory Breath-hold and During Free Breathing.

PubMed

Ajlan, Amr M; Binzaqr, Salma; Jadkarim, Dalia A; Jamjoom, Lamia G; Leipsic, Jonathon

2016-01-01

The purpose of this study was to compare qualitative and quantitative image parameters of dual-source high-pitch helical computed tomographic pulmonary angiography (CTPA) in breath-holding (BH) versus free-breathing (FB) patients. Ninety-nine consented patients (61 female individuals; mean age±SD, 49±18.7 y) were randomized into BH (n=45) versus FB (n=54) high-pitch helical CTPA. Patient characteristics and CTPA radiation doses were analyzed. Two readers assessed for pulmonary embolism (PE), transient interruption of contrast, and respiratory and cardiac motion. The readers used a subjective 3-point scale to rate the pulmonary artery opacification and lung parenchymal appearance. A single reader assessed mean pulmonary artery signal intensity, noise, contrast, signal to noise ratio, and contrast to noise ratio. PE was diagnosed in 16% BH and 19% FB patients. CTPAs of both groups were of excellent or acceptable quality for PE evaluation and of similar mean radiation doses (1.3 mSv). Transient interruption of contrast was seen in 5/45 (11%) BH and 5/54 (9%) FB patients (not statistically significant, P=0.54). No statistically significant difference was noted in cardiac, diaphragmatic, and lung parenchymal motion. Lung parenchymal assessment was excellent in all cases, except for 5/54 (9%) motion-affected FB cases with acceptable quality (statistically significant, P=0.03). No CTPA was considered nondiagnostic by any of the readers. No objective image quality differences were noted between both groups (P>0.05). High-pitch helical CTPA acquired during BH or in FB yields comparable image quality for the diagnosis of PE and lung pathology, with low radiation exposure. Only a modest increase in lung parenchymal artifacts is encountered in FB high-pitch helical CTPA.

Motion Analysis System for Instruction of Nihon Buyo using Motion Capture

NASA Astrophysics Data System (ADS)

Shinoda, Yukitaka; Murakami, Shingo; Watanabe, Yuta; Mito, Yuki; Watanuma, Reishi; Marumo, Mieko

The passing on and preserving of advanced technical skills has become an important issue in a variety of fields, and motion analysis using motion capture has recently become popular in the research of advanced physical skills. This research aims to construct a system having a high on-site instructional effect on dancers learning Nihon Buyo, a traditional dance in Japan, and to classify Nihon Buyo dancing according to style, school, and dancer's proficiency by motion analysis. We have been able to study motion analysis systems for teaching Nihon Buyo now that body-motion data can be digitized and stored by motion capture systems using high-performance computers. Thus, with the aim of developing a user-friendly instruction-support system, we have constructed a motion analysis system that displays a dancer's time series of body motions and center of gravity for instructional purposes. In this paper, we outline this instructional motion analysis system based on three-dimensional position data obtained by motion capture. We also describe motion analysis that we performed based on center-of-gravity data obtained by this system and motion analysis focusing on school and age group using this system.

Cardiac Position Sensitivity Study in the Electrocardiographic Forward Problem Using Stochastic Collocation and Boundary Element Methods

PubMed Central

Swenson, Darrell J.; Geneser, Sarah E.; Stinstra, Jeroen G.; Kirby, Robert M.; MacLeod, Rob S.

2012-01-01

The electrocardiogram (ECG) is ubiquitously employed as a diagnostic and monitoring tool for patients experiencing cardiac distress and/or disease. It is widely known that changes in heart position resulting from, for example, posture of the patient (sitting, standing, lying) and respiration significantly affect the body-surface potentials; however, few studies have quantitatively and systematically evaluated the effects of heart displacement on the ECG. The goal of this study was to evaluate the impact of positional changes of the heart on the ECG in the specific clinical setting of myocardial ischemia. To carry out the necessary comprehensive sensitivity analysis, we applied a relatively novel and highly efficient statistical approach, the generalized polynomial chaos-stochastic collocation method, to a boundary element formulation of the electrocardiographic forward problem, and we drove these simulations with measured epicardial potentials from whole-heart experiments. Results of the analysis identified regions on the body-surface where the potentials were especially sensitive to realistic heart motion. The standard deviation (STD) of ST-segment voltage changes caused by the apex of a normal heart, swinging forward and backward or side-to-side was approximately 0.2 mV. Variations were even larger, 0.3 mV, for a heart exhibiting elevated ischemic potentials. These variations could be large enough to mask or to mimic signs of ischemia in the ECG. Our results suggest possible modifications to ECG protocols that could reduce the diagnostic error related to postural changes in patients possibly suffering from myocardial ischemia. PMID:21909818

SU-F-I-15: Evaluation of a New MR-Compatible Respiratory Motion Device at 3T

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soliman, A; Sunnybrook Health Sciences Centre, Toronto, ON; Chugh, B

Purpose: Recent advances in MRI-guided radiotherapy has inspired the development of MRI-compatible motion devices that simulate patient periodic motion in the scanner, particularly respiratory motion. Most commercial devices rely on non MR-safe ferromagnetic stepper motors which are not practical for regular QA testing. This work evaluates the motion performance of a new fully MRI compatible respiratory motion device at 3T. Methods: The QUASAR™ MRI-compatible respiratory motion phantom has been recently developed by Modus QA Inc., London, ON, Canada. The prototype is constructed from diamagnetic materials with linear motion generated using MRI-compatible piezoelectric motors that can be safely inserted in themore » scanner bore. The tumor was represented by a fillable sphere and is attached to the linear motion generator. The spherical tumor-representative and its surroundings were filled with different concentrations of MnCl2 to produce realistic relaxation times. The motion was generated along the longitudinal (H/F) axis of the bore using sinusoidal reference waveform (amplitude = 15 mm, frequency 0.25 Hz). Imaging was then performed on 3T Philips Achieva using a 32-channel cardiac coil. Fast 2D spoiled gradient-echo was used with a spatial resolution of 1.8 × 1.8 mm{sup 2} and slice thickness of 4 mm. The motion waveform was then measured on the resultant image series by tracking the centroid of the sphere through the time series. This image-derived measured motion was compared to the software-generated reference waveform. Results: No visible distortions from the device were observed on the images. Excellent agreement between the measured and the reference waveforms were obtained. Negligible motion was observed in the lateral (R/L) direction. Conclusion: Our investigation demonstrates that this piezo-electric motor design is effective at simulating periodic motion and is a potential candidate for MRI-radiotherapy respiratory motion simulation. Future work should focus on evaluating non-sinusoidal waveforms, fast 3D pulse sequences, and perform dosimetric QA.« less

Processing and analysis of cardiac optical mapping data obtained with potentiometric dyes

PubMed Central

Laughner, Jacob I.; Ng, Fu Siong; Sulkin, Matthew S.; Arthur, R. Martin

2012-01-01

Optical mapping has become an increasingly important tool to study cardiac electrophysiology in the past 20 years. Multiple methods are used to process and analyze cardiac optical mapping data, and no consensus currently exists regarding the optimum methods. The specific methods chosen to process optical mapping data are important because inappropriate data processing can affect the content of the data and thus alter the conclusions of the studies. Details of the different steps in processing optical imaging data, including image segmentation, spatial filtering, temporal filtering, and baseline drift removal, are provided in this review. We also provide descriptions of the common analyses performed on data obtained from cardiac optical imaging, including activation mapping, action potential duration mapping, repolarization mapping, conduction velocity measurements, and optical action potential upstroke analysis. Optical mapping is often used to study complex arrhythmias, and we also discuss dominant frequency analysis and phase mapping techniques used for the analysis of cardiac fibrillation. PMID:22821993

Registration of 4D time-series of cardiac images with multichannel Diffeomorphic Demons.

PubMed

Peyrat, Jean-Marc; Delingette, Hervé; Sermesant, Maxime; Pennec, Xavier; Xu, Chenyang; Ayache, Nicholas

2008-01-01

In this paper, we propose a generic framework for intersubject non-linear registration of 4D time-series images. In this framework, spatio-temporal registration is defined by mapping trajectories of physical points as opposed to spatial registration that solely aims at mapping homologous points. First, we determine the trajectories we want to register in each sequence using a motion tracking algorithm based on the Diffeomorphic Demons algorithm. Then, we perform simultaneously pairwise registrations of corresponding time-points with the constraint to map the same physical points over time. We show this trajectory registration can be formulated as a multichannel registration of 3D images. We solve it using the Diffeomorphic Demons algorithm extended to vector-valued 3D images. This framework is applied to the inter-subject non-linear registration of 4D cardiac CT sequences.

Increased Rate of Poor Laryngoscopic Views in Patients Scheduled for Cardiac Surgery Versus Patients Scheduled for General Surgery: A Propensity Score-Based Analysis of 21,561 Cases.

PubMed

Heinrich, Sebastian; Ackermann, Andreas; Prottengeier, Johannes; Castellanos, Ixchel; Schmidt, Joachim; Schüttler, Jürgen

2015-12-01

Former analyses reported an increased rate of poor direct laryngoscopy view in cardiac surgery patients; however, these findings frequently could be attributed to confounding patient characteristics. In most of the reported cardiac surgery cohorts, the rate of well-known risk factors for poor direct laryngoscopy view such as male sex, obesity, or older age, were increased compared with the control groups. Especially in the ongoing debate on anesthesia staff qualification for cardiac interventions outside the operating room a detailed and stratified risk analysis seems necessary. Retrospective, anonymous, propensity score-based, matched-pair analysis. Single-center study in a university hospital. No active participants. Retrospective, anonymous chart analysis. The anesthesia records of patients undergoing cardiac surgery in a period of 6 consecutive years were analyzed retrospectively. The results were compared with those of a control group of patients who underwent general surgery. Poor laryngoscopic view was defined as Cormack and Lehane classification grade 3 or 4. The records of 21,561 general anesthesia procedures were reviewed for the study. The incidence of poor direct laryngoscopic views in patients scheduled for cardiac surgery was significantly increased compared with those of the general surgery cohort (7% v 4.2%). Using propensity score-based matched-pair analysis, equal subgroups were generated of each surgical department, with 2,946 patients showing identical demographic characteristics. After stratifying for demographic characteristics, the rate of poor direct laryngoscopy view remained statistically significantly higher in the cardiac surgery group (7.5% v 5.7%). Even with stratification for demographic risk factors, cardiac surgery patients showed a significantly higher rate of poor direct laryngoscopic view compared with general surgery patients. These results should be taken into account for human resource management and distribution of difficult airway equipment, especially when cardiac interventional programs are implemented in remote hospital locations. Copyright © 2015 Elsevier Inc. All rights reserved.

Automatic detection of blood versus non-blood regions on intravascular ultrasound (IVUS) images using wavelet packet signatures

NASA Astrophysics Data System (ADS)

Katouzian, Amin; Baseri, Babak; Konofagou, Elisa E.; Laine, Andrew F.

2008-03-01

Intravascular ultrasound (IVUS) has been proven a reliable imaging modality that is widely employed in cardiac interventional procedures. It can provide morphologic as well as pathologic information on the occluded plaques in the coronary arteries. In this paper, we present a new technique using wavelet packet analysis that differentiates between blood and non-blood regions on the IVUS images. We utilized the multi-channel texture segmentation algorithm based on the discrete wavelet packet frames (DWPF). A k-mean clustering algorithm was deployed to partition the extracted textural features into blood and non-blood in an unsupervised fashion. Finally, the geometric and statistical information of the segmented regions was used to estimate the closest set of pixels to the lumen border and a spline curve was fitted to the set. The presented algorithm may be helpful in delineating the lumen border automatically and more reliably prior to the process of plaque characterization, especially with 40 MHz transducers, where appearance of the red blood cells renders the border detection more challenging, even manually. Experimental results are shown and they are quantitatively compared with manually traced borders by an expert. It is concluded that our two dimensional (2-D) algorithm, which is independent of the cardiac and catheter motions performs well in both in-vivo and in-vitro cases.

Diffusion MRI in the heart.

PubMed

Mekkaoui, Choukri; Reese, Timothy G; Jackowski, Marcel P; Bhat, Himanshu; Sosnovik, David E

2017-03-01

Diffusion MRI provides unique information on the structure, organization, and integrity of the myocardium without the need for exogenous contrast agents. Diffusion MRI in the heart, however, has proven technically challenging because of the intrinsic non-rigid deformation during the cardiac cycle, displacement of the myocardium due to respiratory motion, signal inhomogeneity within the thorax, and short transverse relaxation times. Recently developed accelerated diffusion-weighted MR acquisition sequences combined with advanced post-processing techniques have improved the accuracy and efficiency of diffusion MRI in the myocardium. In this review, we describe the solutions and approaches that have been developed to enable diffusion MRI of the heart in vivo, including a dual-gated stimulated echo approach, a velocity- (M 1 ) or an acceleration- (M 2 ) compensated pulsed gradient spin echo approach, and the use of principal component analysis filtering. The structure of the myocardium and the application of these techniques in ischemic heart disease are also briefly reviewed. The advent of clinical MR systems with stronger gradients will likely facilitate the translation of cardiac diffusion MRI into clinical use. The addition of diffusion MRI to the well-established set of cardiovascular imaging techniques should lead to new and complementary approaches for the diagnosis and evaluation of patients with heart disease. © 2015 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd. © 2015 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.

The use of echocardiography in Wolff-Parkinson-White syndrome.

PubMed

Cai, Qiangjun; Shuraih, Mossaab; Nagueh, Sherif F

2012-04-01

Endocardial mapping and radiofrequency catheter ablation are well established modalities for the diagnosis and treatment of patients with Wolff-Parkinson-White (WPW) syndrome associated with tachyarrhythmias. However, the electrophysiologic techniques are invasive, require radiation exposure, and lack spatial resolution of cardiac structures. A variety of echocardiographic techniques have been investigated as a non-invasive alternative for accessory pathway localization. Conventional M-mode echocardiography can detect the fine premature wall motion abnormalities associated with WPW syndrome. However, it is unable to identify the exact site of accessory pathway with sufficient accuracy. 2D, 2D-guided M-mode, and 2D phase analysis techniques are limited by image quality and endocardial border definition. Various modalities of tissue Doppler echocardiography significantly increase the accuracy of left-sided accessory pathway localization to 80-90% even in patients with poor acoustic window. However, right-sided pathways remain a diagnostic challenge. Strain echocardiography by speckle tracking has recently been evaluated and appears promising. Different cardiac abnormalities have been detected by echocardiography in WPW patients. Patients with WPW syndrome and tachyarrhythmias have impaired systolic and diastolic function which improves after radiofrequency ablation. Echocardiography is useful in identifying patient with accessory pathway-associated left ventricular dyssynchrony and dysfunction who may benefit from ablation therapy. Transesophageal and intracardiac echocardiography have been used to guide ablation procedure. Ablation-related complications detected by routine echocardiography are infrequent, rarely clinically relevant, and of limited value.

Dosimetric Predictors of Symptomatic Cardiac Events after Conventional-Dose Chemoradiation Therapy for Inoperable Non-Small Cell Lung Cancer.

PubMed

Yegya-Raman, Nikhil; Wang, Kyle; Kim, Sinae; Reyhan, Meral; Deek, Matthew P; Sayan, Mutlay; Li, Diana; Patel, Malini; Malhotra, Jyoti; Aisner, Joseph; Marks, Lawrence B; Jabbour, Salma K

2018-06-05

We hypothesized that higher cardiac doses correlates with clinically significant cardiotoxicity after standard-dose chemoradiation therapy (CRT) (∼60 Gy) for inoperable non-small cell lung cancer (NSCLC). We retrospectively reviewed the records of 140 patients with inoperable NSCLC treated with concurrent CRT from 2007-2015. Extracted data included baseline cardiac status, dosimetric parameters to the whole heart (WH) and cardiac substructures, and the development of post-CRT symptomatic cardiac events (acute coronary syndrome [ACS], arrhythmia, pericardial effusion, pericarditis, and congestive heart failure [CHF]). Competing risks analysis was used to estimate time to cardiac events. Median follow-up was 47.4 months. Median radiation therapy dose was 61.2 Gy (interquartile range, 60-66 Gy). Forty patients (28.6%) developed 47 symptomatic cardiac events at a median of 15.3 months to first event. On multivariate analysis, higher WH doses and baseline cardiac status were associated with an increased risk of symptomatic cardiac events. The 4-year cumulative incidence of symptomatic cardiac events was 48.6% versus 18.5% for mean WH dose ≥ 20 Gy versus < 20 Gy, respectively (p = 0.0002). Doses to the WH, ventricles, and left anterior descending artery were associated with ACS/CHF, whereas doses to the WH and atria were not associated with supraventricular arrhythmias. Symptomatic cardiac events (p = 0.0001) were independently associated with death. Incidental cardiac irradiation was associated with subsequent symptomatic cardiac events, particularly ACS/CHF, and symptomatic cardiac events were associated with inferior survival. These results support the minimization of cardiac doses among patients with inoperable NSCLC receiving standard-dose CRT. Copyright © 2018 International Association for the Study of Lung Cancer. Published by Elsevier Inc. All rights reserved.

Towards continuous monitoring of pulse rate in neonatal intensive care unit with a webcam.

PubMed

Mestha, Lalit K; Kyal, Survi; Xu, Beilei; Lewis, Leslie Edward; Kumar, Vijay

2014-01-01

We describe a novel method to monitor pulse rate (PR) on a continuous basis of patients in a neonatal intensive care unit (NICU) using videos taken from a high definition (HD) webcam. We describe algorithms that determine PR from videoplethysmographic (VPG) signals extracted from multiple regions of interest (ROI) simultaneously available within the field of view of the camera where cardiac signal is registered. We detect motion from video images and compensate for motion artifacts from each ROI. Preliminary clinical results are presented on 8 neonates each with 30 minutes of uninterrupted video. Comparisons to hospital equipment indicate that the proposed technology can meet medical industry standards and give improved patient comfort and ease of use for practitioners when instrumented with proper hardware.

Life in motion, in motion!

NASA Technical Reports Server (NTRS)

Kovalenko, Y. A.

1983-01-01

A 120 day limited mobility experiment with young male rats and its results, including retarded growth and degenerative changes in the cardiac muscle, are described. A 120 day strict bedrest experiment with 10 human volunteers and its results are described and discussed. Early subjective complaints, subsequent adaptation and eventual progressive changes in excitability and reactivity, reduction in functional capability of the cerebral cortex, and disturbances in water-salt, protein and fat metabolism, including development of precursors of atherosclerosis, as well as poor results of the orthostatic test after 4 months, are presented. These results are explained as applied to sedentary workers and recommendations are given for such persons to exercise in the morning, at work and in the evening in order to prevent hypokinesis and its physical, mental and physiological effects.

The da Vinci telerobotic surgical system: the virtual operative field and telepresence surgery.

PubMed

Ballantyne, Garth H; Moll, Fred

2003-12-01

The United States Department of Defense developed the telepresence surgery concept to meet battlefield demands. The da Vinci telerobotic surgery system evolved from these efforts. In this article, the authors describe the components of the da Vinci system and explain how the surgeon sits at a computer console, views a three-dimensional virtual operative field, and performs the operation by controlling robotic arms that hold the stereoscopic video telescope and surgical instruments that simulate hand motions with seven degrees of freedom. The three-dimensional imaging and handlike motions of the system facilitate advanced minimally invasive thoracic, cardiac, and abdominal procedures. da Vinci has recently released a second generation of telerobots with four arms and will continue to meet the evolving challenges of surgery.

Acute ECG changes and chest pain induced by neck motion in patients with cervical hernia--a case report.

PubMed

Güler, N; Bilge, M; Eryonucu, B; Cirak, B

2000-10-01

We report two cases of acute cervical angina and ECG changes induced by anteflexion of the head. Cervical angina is defined as chest pain that resembles true cardiac angina but originates from cervical discopathy with nerve root compression. In these patients, Prinzmetal's angina, valvular heart disease, congenital heart disease, left ventricular aneurysm, and cardiomyopathy were excluded. After all, the patient's chest pain was reproduced by anteflexion of head, at this time, their ECGs showed nonspecific ST-T changes in the inferior and anterior leads different from the basal ECG. ECG changes returned to normal when the patient's neck moved to the neutral position. To our knowledge, these are the first cases of cervical angina associated with acute ECG changes by neck motion.

Interrogating the origin and behavior of magnetic resonance diffusion tensor scalar parameters in the myocardium

NASA Astrophysics Data System (ADS)

Abdullah, Osama Mahmoud

Myocardial microstructure plays an important role in sustaining the orchestrated beating motion of the heart. Several microstructural components, including myocytes and auxiliary cells, extracellular space, and blood vessels provide the infrastructure for normal heart function, including excitation propagation, myocyte contraction, delivery of oxygen and nutrients, and removing byproduct wastes. Cardiac diseases cause deleterious changes to some or all of these microstructural components in the detrimental process of cardiac remodeling. Since heart failure is among the leading causes of death in the world, new and novel tools to noninvasively characterize heart microstructure are needed for monitoring and staging of cardiac disease. In this regards, diffusion magnetic resonance imaging (MRI) provides a promising framework to probe and quantify tissue microstructure without the need for exogenous contrast agent. As diffusion in 3-dimensional space is characterized by the diffusion tensor, MR diffusion tensor imaging (DTI) is being used to noninvasively measure anisotropic diffusion, and thus the magnitude and spatial orientation of microstructural organization of tissues, including the heart. However, even though in vivo cardiac DTI has become more clinically available, to date the origin and behavior of different microstructural components on the measured DTI signal remain to be explicitly specified. The presented studies in this work demonstrate that DTI can be used as a noninvasive and contrast-free imaging modality to characterize myocyte size and density, extracellular collagen content, and the directional magnitude of blood flow. The identified applications are expected to provide metrics to enable physicians to detect, quantify, and stage different microstructural components during progression of cardiac disease.

Seismocardiography-Based Cardiac Computed Tomography Gating Using Patient-Specific Template Identification and Detection

PubMed Central

Yao, Jingting; Tridandapani, Srini; Wick, Carson A.

2017-01-01

To more accurately trigger cardiac computed tomography angiography (CTA) than electrocardiography (ECG) alone, a sub-system is proposed as an intermediate step toward fusing ECG with seismocardiography (SCG). Accurate prediction of quiescent phases is crucial to prospectively gating CTA, which is susceptible to cardiac motion and, thus, can affect the diagnostic quality of images. The key innovation of this sub-system is that it identifies the SCG waveform corresponding to heart sounds and determines their phases within the cardiac cycles. Furthermore, this relationship is modeled as a linear function with respect to heart rate. For this paper, B-mode echocardiography is used as the gold standard for identifying the quiescent phases. We analyzed synchronous ECG, SCG, and echocardiography data acquired from seven healthy subjects (mean age: 31; age range: 22–48; males: 4) and 11 cardiac patients (mean age: 56; age range: 31–78; males: 6). On average, the proposed algorithm was able to successfully identify 79% of the SCG waveforms in systole and 68% in diastole. The simulated results show that SCG-based prediction produced less average phase error than that of ECG. It was found that the accuracy of ECG-based gating is more susceptible to increases in heart rate variability, while SCG-based gating is susceptible to high cycle to cycle variability in morphology. This pilot work of prediction using SCG waveforms enriches the framework of a comprehensive system with multiple modalities that could potentially, in real time, improve the image quality of CTA. PMID:28845370

Motion correction for improving the accuracy of dual-energy myocardial perfusion CT imaging

NASA Astrophysics Data System (ADS)

Pack, Jed D.; Yin, Zhye; Xiong, Guanglei; Mittal, Priya; Dunham, Simon; Elmore, Kimberly; Edic, Peter M.; Min, James K.

2016-03-01

Coronary Artery Disease (CAD) is the leading cause of death globally [1]. Modern cardiac computed tomography angiography (CCTA) is highly effective at identifying and assessing coronary blockages associated with CAD. The diagnostic value of this anatomical information can be substantially increased in combination with a non-invasive, low-dose, correlative, quantitative measure of blood supply to the myocardium. While CT perfusion has shown promise of providing such indications of ischemia, artifacts due to motion, beam hardening, and other factors confound clinical findings and can limit quantitative accuracy. In this paper, we investigate the impact of applying a novel motion correction algorithm to correct for motion in the myocardium. This motion compensation algorithm (originally designed to correct for the motion of the coronary arteries in order to improve CCTA images) has been shown to provide substantial improvements in both overall image quality and diagnostic accuracy of CCTA. We have adapted this technique for application beyond the coronary arteries and present an assessment of its impact on image quality and quantitative accuracy within the context of dual-energy CT perfusion imaging. We conclude that motion correction is a promising technique that can help foster the routine clinical use of dual-energy CT perfusion. When combined, the anatomical information of CCTA and the hemodynamic information from dual-energy CT perfusion should facilitate better clinical decisions about which patients would benefit from treatments such as stent placement, drug therapy, or surgery and help other patients avoid the risks and costs associated with unnecessary, invasive, diagnostic coronary angiography procedures.

The role of remote ischemic preconditioning in organ protection after cardiac surgery: a meta-analysis.

PubMed

Haji Mohd Yasin, Nur A B; Herbison, Peter; Saxena, Pankaj; Praporski, Slavica; Konstantinov, Igor E

2014-01-01

Remote ischemic preconditioning (RIPC) appears to protect distant organs from ischemia-reperfusion injury. We undertook meta-analysis of clinical studies to evaluate the effects of RIPC on organ protection and clinical outcomes in patients undergoing cardiac surgery. A review of evidence for cardiac, renal, and pulmonary protection after RIPC was performed. We also did meta-regressions on RIPC variables, such as duration of ischemia, cuff pressure, and timing of application of preconditioning. Secondary outcomes included length of hospital and intensive care unit stay, duration of mechanical ventilation, and mortality at 30 days. Randomized control trials (n = 25) were included in the study for quantitative analysis of cardiac (n = 16), renal (n = 6), and pulmonary (n = 3) protection. RIPC provided statistically significant cardiac protection (standardized mean difference [SMD], -0.77; 95% confidence interval [CI], -1.15, -0.39; Z = 3.98; P < 0.0001) and on subgroup analysis, the protective effect remained consistent for all types of cardiac surgical procedures. However, there was no evidence of renal protection (SMD, 0.74; 95% CI, 0.53, 1.02; Z = 1.81; P = 0.07) or pulmonary protection (SMD, -0.03; 95% CI, -0.56, 0.50; Z = 0.12; P = 0.91). There was no statistical difference in the short-term clinical outcomes between the RIPC and control groups. RIPC provides cardiac protection, but there is no evidence of renal or pulmonary protection in patients undergoing cardiac surgery using cardiopulmonary bypass. Larger multicenter trials are required to define the role of RIPC in surgical practice. Crown Copyright © 2014. Published by Elsevier Inc. All rights reserved.

Physiotherapy-supervised mobilization and exercise following cardiac surgery: a national questionnaire survey in Sweden.

PubMed

Westerdahl, Elisabeth; Möller, Margareta

2010-08-25

Limited published data are available on how patients are mobilized and exercised during the postoperative hospital stay following cardiac surgery. The aim of this survey was to determine current practice of physiotherapy-supervised mobilization and exercise following cardiac surgery in Sweden. A prospective survey was carried out among physiotherapists treating adult cardiac surgery patients. A total population sample was identified and postal questionnaires were sent to the 33 physiotherapists currently working at the departments of thoracic surgery in Sweden. In total, 29 physiotherapists (response rate 88%) from eight hospitals completed the survey. The majority (90%) of the physiotherapists offered preoperative information. The main rationale of physiotherapy treatment after cardiac surgery was to prevent and treat postoperative complications, improve pulmonary function and promote physical activity. In general, one to three treatment sessions were given by a physiotherapist on postoperative day 1 and one to two treatment sessions were given during postoperative days 2 and 3. During weekends, physiotherapy was given to a lesser degree (59% on Saturdays and 31% on Sundays to patients on postoperative day 1). No physiotherapy treatment was given in the evenings. The routine use of early mobilization and shoulder range of motion exercises was common during the first postoperative days, but the choice of exercises and duration of treatment varied. Patients were reminded to adhere to sternal precautions. There were great variations of instructions to the patients concerning weight bearing and exercises involving the sternotomy. All respondents considered physiotherapy necessary after cardiac surgery, but only half of them considered the physiotherapy treatment offered as optimal. The results of this survey show that there are small variations in physiotherapy-supervised mobilization and exercise following cardiac surgery in Sweden. However, the frequency and duration of exercises and recommendations for sternal precautions reinforced for the healing period differ between physiotherapists. This survey provides an initial insight into physiotherapy management in Sweden. Comparison with surveys in other countries is warranted to improve the physiotherapy management and postoperative recovery of the cardiac surgery patient.

Physiotherapy-supervised mobilization and exercise following cardiac surgery: a national questionnaire survey in Sweden

PubMed Central

2010-01-01

Background Limited published data are available on how patients are mobilized and exercised during the postoperative hospital stay following cardiac surgery. The aim of this survey was to determine current practice of physiotherapy-supervised mobilization and exercise following cardiac surgery in Sweden. Methods A prospective survey was carried out among physiotherapists treating adult cardiac surgery patients. A total population sample was identified and postal questionnaires were sent to the 33 physiotherapists currently working at the departments of thoracic surgery in Sweden. In total, 29 physiotherapists (response rate 88%) from eight hospitals completed the survey. Results The majority (90%) of the physiotherapists offered preoperative information. The main rationale of physiotherapy treatment after cardiac surgery was to prevent and treat postoperative complications, improve pulmonary function and promote physical activity. In general, one to three treatment sessions were given by a physiotherapist on postoperative day 1 and one to two treatment sessions were given during postoperative days 2 and 3. During weekends, physiotherapy was given to a lesser degree (59% on Saturdays and 31% on Sundays to patients on postoperative day 1). No physiotherapy treatment was given in the evenings. The routine use of early mobilization and shoulder range of motion exercises was common during the first postoperative days, but the choice of exercises and duration of treatment varied. Patients were reminded to adhere to sternal precautions. There were great variations of instructions to the patients concerning weight bearing and exercises involving the sternotomy. All respondents considered physiotherapy necessary after cardiac surgery, but only half of them considered the physiotherapy treatment offered as optimal. Conclusions The results of this survey show that there are small variations in physiotherapy-supervised mobilization and exercise following cardiac surgery in Sweden. However, the frequency and duration of exercises and recommendations for sternal precautions reinforced for the healing period differ between physiotherapists. This survey provides an initial insight into physiotherapy management in Sweden. Comparison with surveys in other countries is warranted to improve the physiotherapy management and postoperative recovery of the cardiac surgery patient. PMID:20738852

Attitudes, risk of infection and behaviours in the operating room (the ARIBO Project): a prospective, cross-sectional study

PubMed Central

Birgand, Gabriel; Azevedo, Christine; Toupet, Gaelle; Pissard-Gibollet, Roger; Grandbastien, Bruno; Fleury, Eric; Lucet, Jean-Christophe

2014-01-01

Introduction Inappropriate staff behaviours can lead to environmental contamination in the operating room (OR) and subsequent surgical site infection (SSI). This study will focus on the continued assessment of OR staff behaviours using a motion tracking system and their impact on the SSI risk during surgical procedures. Methods and analysis This multicentre prospective cross-sectional study will include 10 ORs of cardiac and orthopaedic surgery in 12 healthcare facilities (HCFs). The staff behaviour will be assessed by an objective, continued and prolonged quantification of movements within the OR. A motion tracking system including eight optical cameras (VICON-Bonita) will record the movements of reflective markers placed on the surgical caps/hoods of each person entering the room. Different configurations of markers positioning will be used to distinguish between the staff category. Doors opening will be observed by means of wireless inertial sensors fixed on the doors and synchronised with the motion tracking system. We will collect information on the OR staff, surgical procedures and surgical environment characteristics. The behavioural data obtained will be compared (1) to the ‘best behaviour rules’ in the OR, pre-established using a Delphi method and (2) to surrogates of the infectious risk represented by microbiological air counts, particle counts, and a bacteriological sample of the wound at closing. Statistics will be performed using univariate and multivariate analysis to adjust on the aerolic and architectural characteristics of the OR. A multilevel model will allow including surgical specialty and HCFs effects. Through this study, we will develop an original approach using high technology tools associated to data processing techniques to evaluate ‘automatically’ the behavioural dynamics of the OR staff and their impact on the SSI risk. Ethics and dissemination Approbation of the Institutional Review Board of Paris North Hospitals, Paris 7 University, AP-HP (no 11-113, 6 April 2012). The findings will be disseminated through peer-reviewed journals, and national and international conference presentations. PMID:24384903

Ginseng Is Useful to Enhance Cardiac Contractility in Animals

PubMed Central

Cherng, Yih-Giun; Chen, Li-Jen; Niu, Ho-Shan; Chang, Chen Kuei; Niu, Chiang-Shan

2014-01-01

Ginseng has been shown to be effective on cardiac dysfunction. Recent evidence has highlighted the mediation of peroxisome proliferator-activated receptors (PPARs) in cardiac function. Thus, we are interested to investigate the role of PPARδ in ginseng-induced modification of cardiac contractility. The isolated hearts in Langendorff apparatus and hemodynamic analysis in catheterized rats were applied to measure the actions of ginseng ex vivo and in vivo. In normal rats, ginseng enhanced cardiac contractility and hemodynamic dP/dt max significantly. Both actions were diminished by GSK0660 at a dose enough to block PPARδ. However, ginseng failed to modify heart rate at the same dose, although it did produce a mild increase in blood pressure. Data of intracellular calcium level and Western blotting analysis showed that both the PPARδ expression and troponin I phosphorylation were raised by ginseng in neonatal rat cardiomyocyte. Thus, we suggest that ginseng could enhance cardiac contractility through increased PPARδ expression in cardiac cells. PMID:24689053

The UNC-45 Chaperone Is Critical for Establishing Myosin-Based Myofibrillar Organization and Cardiac Contractility in the Drosophila Heart Model

PubMed Central

Melkani, Girish C.; Bodmer, Rolf; Ocorr, Karen; Bernstein, Sanford I.

2011-01-01

UNC-45 is a UCS (UNC-45/CRO1/She4P) class chaperone necessary for myosin folding and/or accumulation, but its requirement for maintaining cardiac contractility has not been explored. Given the prevalence of myosin mutations in eliciting cardiomyopathy, chaperones like UNC-45 are likely to be equally critical in provoking or modulating myosin-associated cardiomyopathy. Here, we used the Drosophila heart model to examine its role in cardiac physiology, in conjunction with RNAi-mediated gene silencing specifically in the heart in vivo. Analysis of cardiac physiology was carried out using high-speed video recording in conjunction with movement analysis algorithms. unc-45 knockdown resulted in severely compromised cardiac function in adults as evidenced by prolonged diastolic and systolic intervals, and increased incidence of arrhythmias and extreme dilation; the latter was accompanied by a significant reduction in muscle contractility. Structural analysis showed reduced myofibrils, myofibrillar disarray, and greatly decreased cardiac myosin accumulation. Cardiac unc-45 silencing also dramatically reduced life-span. In contrast, third instar larval and young pupal hearts showed mild cardiac abnormalities, as severe cardiac defects only developed during metamorphosis. Furthermore, cardiac unc-45 silencing in the adult heart (after metamorphosis) led to less severe phenotypes. This suggests that UNC-45 is mostly required for myosin accumulation/folding during remodeling of the forming adult heart. The cardiac defects, myosin deficit and decreased life-span in flies upon heart-specific unc-45 knockdown were significantly rescued by UNC-45 over-expression. Our results are the first to demonstrate a cardiac-specific requirement of a chaperone in Drosophila, suggestive of a critical role of UNC-45 in cardiomyopathies, including those associated with unfolded proteins in the failing human heart. The dilated cardiomyopathy phenotype associated with UNC-45 deficiency is mimicked by myosin knockdown suggesting that UNC-45 plays a crucial role in stabilizing myosin and possibly preventing human cardiomyopathies associated with functional deficiencies of myosin. PMID:21799905

Subclinical and clinical correlates of left ventricular wall motion abnormalities in the community.

PubMed

Tsao, Connie W; Gona, Philimon; Salton, Carol; Danias, Peter G; Blease, Susan; Hoffmann, Udo; Fox, Caroline S; Albert, Mark; Levy, Daniel; O'Donnell, Christopher J; Manning, Warren J; Yeon, Susan B

2011-03-15

The prevalence and clinical correlates of left ventricular (LV) wall motion abnormalities (WMAs), associated with morbidity and mortality, have not been well-characterized in the population. Framingham Heart Study Offspring Cohort participants (n = 1,794, 844 men, age 65 ± 9 years) underwent cine cardiovascular magnetic resonance for evaluation of LV function. A subset (n = 1,009, 460 men) underwent cardiac multidetector computed tomography for analysis of coronary artery calcium. The presence of coronary heart disease and heart failure (CHD-HF) were assessed in relation to the presence of WMAs. WMAs were present in 117 participants (6.5%) and were associated with male gender, elevated hemoglobin A1c, LV mass, LV end-diastolic volume, and lower LV ejection fraction. Of the 1,637 participants without CHD-HF, 68 (4.2%) had WMAs. In this group, WMAs were associated with obesity, hypertension, and Framingham coronary heart disease risk score in the age- and gender-adjusted analyses and were associated with male gender and hypertension on multivariate analysis. Most subjects with WMAs were in the greatest coronary artery calcium groups. The presence of coronary artery calcium greater than the seventy-fifth percentile and Agatston score >100 were associated with a greater than twofold risk of WMAs in the age- and gender-adjusted analysis but were no longer significant when additionally adjusted for CHD-HF. Previous Q-wave myocardial infarction was present in 29% of the 117 participants with WMAs. In conclusion, in the present longitudinally followed free-living population, 4.2% of the participants without CHD-HF had WMAs. WMAs were associated with the clinical parameters associated with cardiovascular disease risk. Aggressive risk factor modification may be prudent for subjects with WMAs, particularly those free of clinical CHD-HF. Copyright © 2011 Elsevier Inc. All rights reserved.

Myocardial perfusion MRI with sliding-window conjugate-gradient HYPR.

PubMed

Ge, Lan; Kino, Aya; Griswold, Mark; Mistretta, Charles; Carr, James C; Li, Debiao

2009-10-01

First-pass perfusion MRI is a promising technique for detecting ischemic heart disease. However, the diagnostic value of the method is limited by the low spatial coverage, resolution, signal-to-noise ratio (SNR), and cardiac motion-related image artifacts. In this study we investigated the feasibility of using a method that combines sliding window and CG-HYPR methods (SW-CG-HYPR) to reduce the acquisition window for each slice while maintaining the temporal resolution of one frame per heartbeat in myocardial perfusion MRI. This method allows an increased number of slices, reduced motion artifacts, and preserves the relatively high SNR and spatial resolution of the "composite images." Results from eight volunteers demonstrate the feasibility of SW-CG-HYPR for accelerated myocardial perfusion imaging with accurate signal intensity changes of left ventricle blood pool and myocardium. Using this method the acquisition time per cardiac cycle was reduced by a factor of 4 and the number of slices was increased from 3 to 8 as compared to the conventional technique. The SNR of the myocardium at peak enhancement with SW-CG-HYPR (13.83 +/- 2.60) was significantly higher (P < 0.05) than the conventional turbo-FLASH protocol (8.40 +/- 1.62). Also, the spatial resolution of the myocardial perfection images was significantly improved. SW-CG-HYPR is a promising technique for myocardial perfusion MRI. (c) 2009 Wiley-Liss, Inc.

Prognostic value of adrenal gland volume after cardiac arrest: Association of CT-scan evaluation with shock and mortality.

PubMed

Mongardon, Nicolas; Savary, Guillaume; Geri, Guillaume; El Bejjani, Marie-Rose; Silvera, Stéphane; Dumas, Florence; Charpentier, Julien; Pène, Frédéric; Mira, Jean-Paul; Cariou, Alain

2018-05-28

Adrenal gland volume is associated with survival in septic shock. As sepsis and post-cardiac arrest syndrome share many pathophysiological features, we assessed the association between adrenal gland volume measured by computerized tomography (CT)-scan and post-cardiac arrest shock and intensive care unit (ICU) mortality, in a large cohort of out-of-hospital cardiac arrest (OHCA) patients. We also investigated the association between adrenal hormonal function and both adrenal gland volume and outcomes. Prospective analysis of CT-scan performed at hospital admission in patients admitted after OHCA (2007-2012). A pair of blinded radiologist calculated manually adrenal gland volume. In a subgroup of patients, plasma cortisol was measured at admission and 60 min after a cosyntropin test. Factors associated with post-cardiac arrest shock and ICU mortality were identified using multivariate logistic regression. Among 775 patients admitted during this period after OHCA, 138 patients were included: 72 patients (52.2%) developed a post-cardiac arrest shock, and 98 patients (71.1%) died. In univariate analysis, adrenal gland volume was not different between patients with and without post-cardiac arrest shock: 10.6 and 11.3 cm 3 , respectively (p = 0.9) and between patients discharged alive or dead: 10.2 and 11.8 cm 3 , respectively (p = 0.4). Multivariate analysis confirmed that total adrenal gland volume was associated neither with post-cardiac arrest shock nor mortality. Neither baseline cortisol level nor delta between baseline and after cosyntropin test cortisol levels were associated with adrenal volume, post-cardiac arrest shock onset or mortality. After OHCA, adrenal gland volume is not associated with post-cardiac arrest shock onset or ICU mortality. Adrenal gland volume does not predict adrenal gland hormonal response. Copyright © 2018 Elsevier B.V. All rights reserved.

Agreement of Bioreactance Cardiac Output Monitoring With Thermodilution During Hemorrhagic Shock and Resuscitation in Adult Swine.

PubMed

Berlin, David A; Peprah-Mensah, Harrison; Manoach, Seth; Heerdt, Paul M

2017-02-01

The study tests the hypothesis that noninvasive cardiac output monitoring based upon bioreactance (Cheetah Medical, Portland, OR) has acceptable agreement with intermittent bolus thermodilution over a wide range of cardiac output in an adult porcine model of hemorrhagic shock and resuscitation. Prospective laboratory animal investigation. Preclinical university laboratory. Eight ~ 50 kg Yorkshire swine with a femoral artery catheter for blood pressure measurement and a pulmonary artery catheter for bolus thermodilution. With the pigs anesthetized and mechanically ventilated, 40 mL/kg of blood was removed yielding marked hypotension and a rise in plasma lactate. After 60 minutes, pigs were resuscitated with shed blood and crystalloid. Noninvasive cardiac output monitoring and intermittent thermodilution cardiac output were simultaneously measured at nine time points spanning baseline, hemorrhage, and resuscitation. Simultaneous noninvasive cardiac output monitoring and thermodilution measurements of cardiac output were compared by Bland-Altman analysis. A plot was constructed using the difference of each paired measurement expressed as a percentage of the mean of the pair plotted against the mean of the pair. Percent bias was used to scale the differences in the measurements for the magnitude of the cardiac output. Method concordance was assessed from a four-quadrant plot with a 15% zone of exclusion. Overall, noninvasive cardiac output monitoring percent bias was 1.47% (95% CI, -2.5 to 5.4) with limits of agreement of upper equal to 33.4% (95% CI, 26.5-40.2) and lower equal to -30.4% (95% CI, -37.3 to -23.6). Trending analysis demonstrated a 97% concordance between noninvasive cardiac output monitoring and thermodilution cardiac output. Over the wide range of cardiac output produced by hemorrhage and resuscitation in large pigs, noninvasive cardiac output monitoring has acceptable agreement with thermodilution cardiac output.

Magnetic Resonance Imaging as a Predictor of Survival Free of Life-Threatening Arrhythmias and Transplantation in Cardiac Sarcoidosis.

PubMed

Ekström, Kaj; Lehtonen, Jukka; Hänninen, Helena; Kandolin, Riina; Kivistö, Sari; Kupari, Markku

2016-05-02

Cardiac magnetic resonance imaging has a key role in today's diagnosis of cardiac sarcoidosis. We set out to investigate whether cardiac magnetic resonance imaging also helps predict outcome in cardiac sarcoidosis. Our work involved 59 patients with cardiac sarcoidosis (38 female, mean age 46±10 years) seen at our hospital since February 2004 and followed up after contrast-enhanced cardiac magnetic resonance imaging. The extent of myocardial late gadolinium enhancement (measured as percentage of left ventricular mass), the volumes and ejection fractions of the left and right ventricles, and the thickness of the basal interventricular septum were determined and analyzed for prognostic significance. By April 2015, 23 patients had reached the study's end point, consisting of a composite of cardiac death (n=3), cardiac transplantation (n=1), and occurrence of life-threatening ventricular tachyarrhythmias (n=19; ventricular fibrillation in 5 and sustained ventricular tachycardia in 14 patients). In univariate analysis, myocardial extent of late gadolinium enhancement predicted event-free survival, as did scar-like thinning (<4 mm) of the basal interventricular septum and the ejection fraction of the right ventricle (P<0.05 for all). In multivariate Cox regression analysis, extent of late gadolinium enhancement was the only independent predictor of outcome events on cardiac magnetic resonance imaging, with a hazard ratio of 2.22 per tertile (95% CI 1.07-4.59). An extent of late gadolinium enhancement >22% (third tertile) had positive and negative predictive values for serious cardiac events of 75% and 76%, respectively. Findings on cardiac magnetic resonance imaging and the extent of myocardial late gadolinium enhancement in particular help predict serious cardiac events in cardiac sarcoidosis. © 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

Validation of cardiac output studies from the Mostcare compared to a pulmonary artery catheter in septic patients.

PubMed

Gopal, S; Do, T; Pooni, J S; Martinelli, G

2014-03-01

The Mostcare monitor is a non-invasive cardiac output monitor. It has been well validated in cardiac surgical patients but there is limited evidence on its use in patients with severe sepsis and septic shock. The study included the first 22 consecutive patients with severe sepsis and septic shock in whom the floatation of a pulmonary artery catheter was deemed necessary to guide clinical management. Cardiac output measurements including cardiac output, cardiac index and stroke volume were simultaneously calculated and recorded from a thermodilution pulmonary artery catheter and from the Mostcare monitor respectively. The two methods of measuring cardiac output were compared by Bland-Altman statistics and linear regression analysis. A percentage error of less than 30% was defined as acceptable for this study. Bland-Altman analysis for cardiac output showed a Bias of 0.31 L.min-1, precision (=SD) of 1.97 L.min-1 and a percentage error of 62.54%. For Cardiac Index the bias was 0.21 L.min-1.m-2, precision of 1.10 L.min-1.m-2 and a percentage error of 64%. For stroke volume the bias was 5 mL, precision of 24.46 mL and percentage error of 70.21%. Linear regression produced a correlation coefficient r2 for cardiac output, cardiac index, and stroke volume, of 0.403, 0.306, and 0.3 respectively. Compared to thermodilution cardiac output, cardiac output studies obtained from the Mostcare monitor have an unacceptably high error rate. The Mostcare monitor demonstrated to be an unreliable monitoring device to measure cardiac output in patients with severe sepsis and septic shock on an intensive care unit.

Evaluation of several two-dimensional gel electrophoresis techniques in cardiac proteomics.

PubMed

Li, Zhao Bo; Flint, Paul W; Boluyt, Marvin O

2005-09-01

Two-dimensional gel electrophoresis (2-DE) is currently the best method for separating complex mixtures of proteins, and its use is gradually becoming more common in cardiac proteome analysis. A number of variations in basic 2-DE have emerged, but their usefulness in analyzing cardiac tissue has not been evaluated. The purpose of the present study was to systematically evaluate the capabilities and limitations of several 2-DE techniques for separating proteins from rat heart tissue. Immobilized pH gradient strips of various pH ranges, parameters of protein loading and staining, subcellular fractionation, and detection of phosphorylated proteins were studied. The results provide guidance for proteome analysis of cardiac and other tissues in terms of selection of the isoelectric point separating window for cardiac proteins, accurate quantitation of cardiac protein abundance, stabilization of technical variation, reduction of sample complexity, enrichment of low-abundant proteins, and detection of phosphorylated proteins.

Cardiac Versus Non-Cardiac Related Mortality Following Percutaneous Coronary Intervention in Patients with Insulin-Treated Type 2 Diabetes Mellitus: A Meta-Analysis.

PubMed

Wang, Qiang; Liu, Hao; Ding, Jiawang

2018-05-19

Cardiovascular mortality is a major concern for patients with type 2 diabetes mellitus (T2DM). Insulin therapy significantly contributes to a high rate of death in these patients. We have performed a meta-analysis comparing cardiac and non-cardiac-related mortality following percutaneous coronary intervention (PCI) in a sample of patients with insulin-treated type 2 diabetes mellitus (ITDM). Studies were included in the meta-analysis if: (1) they were trials or cohort studies involving patients with T2DM post-PCI; (2) the outcomes in ITDM were separately reported; and (3) they reported cardiac death and non-cardiac death among their clinical endpoints. ITDM patients with any degree of coronary artery disease were included. The analysis was carried out using RevMan version 5.3 software, and data were reported with odds ratios (OR) and 95% confidence intervals (CI) as the main parameters. A total of 4072 participants with ITDM were included, of whom 1658 participants and 2414 participants were extracted from randomized controlled trials and observational cohorts, respectively. Analysis of all data showed that death due to cardiac causes was significantly higher in patients with ITDM (OR 2.16, 95% CI 1.79-2.59; P = 0.00001). At 1 year of follow-up, cardiac death was still significantly higher compared to non-cardiac death (OR 2.39, 95% CI 1.47-3.88; P = 0.0004), and this result did not change with a longer follow-up period (3-5 years) (OR 2.09, 95% CI 1.70-2.56; P = 0.00001). Death due to cardiac causes was still significantly higher in the subpopulations of patients with everolimus-eluting stents (OR 2.31, 95% CI 1.26-4.26; P = 0.007), paclitaxel-eluting stents (OR 2.36, 95% CI 1.63-3.39; P = 0.00001), sirolimus-eluting stents (OR 2.11, 95% CI 1.67-2.67; P = 0.00001), and zotarolimus-eluting stents (OR 2.12, 95% CI 1.11-4.05; P = 0.02), respectively. Mortality due to cardiac causes was significantly higher than that due to non-cardiac causes in patients with ITDM who had undergone PCI. The same conclusion could be drawn from analyses focused on different follow-up periods, types of coronary stents, and type of study data used.

Nuclear cardiac

DOE Office of Scientific and Technical Information (OSTI.GOV)

Slutsky, R.; Ashburn, W.L.

1982-01-01

The relationship between nuclear medicine and cardiology has continued to produce a surfeit of interesting, illuminating, and important reports involving the analysis of cardiac function, perfusion, and metabolism. To simplify the presentation, this review is broken down into three major subheadings: analysis of myocardial perfusion; imaging of the recent myocardial infarction; and the evaluation of myocardial function. There appears to be an increasingly important relationship between cardiology, particularly cardiac physiology, and nuclear imaging techniques. (KRM)

A novel four-wire-driven robotic catheter for radio-frequency ablation treatment.

PubMed

Yoshimitsu, Kitaro; Kato, Takahisa; Song, Sang-Eun; Hata, Nobuhiko

2014-09-01

   Robotic catheters have been proposed to increase the efficacy and safety of the radio-frequency ablation treatment. The robotized motion of current robotic catheters mimics the motion of manual ones-namely, deflection in one direction and rotation around the catheter. With the expectation that the higher dexterity may achieve further efficacy and safety of the robotically driven treatment, we prototyped a four-wire-driven robotic catheter with the ability to deflect in two- degree-of-freedom motions in addition to rotation.    A novel quad-directional structure with two wires was designed and developed to attain yaw and pitch motion in the robotic catheter. We performed a mechanical evaluation of the bendability and maneuverability of the robotic catheter and compared it with current manual catheters.    We found that the four-wire-driven robotic catheter can achieve a pitching angle of 184.7[Formula: see text] at a pulling distance of wire for 11 mm, while the yawing angle was 170.4[Formula: see text] at 11 mm. The robotic catheter could attain the simultaneous two- degree-of-freedom motions in a simulated cardiac chamber.    The results indicate that the four-wire-driven robotic catheter may offer physicians the opportunity to intuitively control a catheter and smoothly approach the focus position that they aim to ablate.

Adverse cardiac events in 56,000 orthopaedic trauma patients: Does anatomic area make a difference?

PubMed

Lee, Adam K; Dodd, Ashley C; Lakomkin, Nikita; Yarlagadda, Mahesh; Jahangir, A Alex; Collinge, Cory A; Sethi, Manish K

2016-08-01

Postoperative cardiac events in orthopaedic trauma patients constitute severe morbidity and mortality. It is therefore increasingly important to determine patient risk factors that are predictive of postoperative myocardial infarctions and cardiac arrests. This study sought to assess if there is an association between anatomic area and cardiac complications in the orthopaedic trauma patient. From 2006-2013, a total of 361,402 orthopaedic patients were identified in the NSQIP database using Current Procedural Terminology (CPT) codes. Of these, 56,336 (15.6%) patients were identified as orthopaedic trauma patients broken down by anatomic region: 11,905 (21.1%) upper extremity patients (UE), 29,009 (51.5%) hip/pelvis patients (HP), and 15,422 (27.4%) lower extremity patients (LE) using CPT codes. Patients were defined as having adverse cardiac events if they developed myocardial infarctions or cardiac arrests within 30days after surgery. Chi-squared analysis was used to determine if there was an association between anatomic area and rates of cardiac events. Multivariate logistical analysis was used with over 40 patient characteristics including age, gender, history of cardiac disease, and anatomic region as independent predictors to determine whether anatomic area significantly predicted the development of cardiac complications. There were significant differences in baseline demographics among the three groups: HP patients had the greatest average age (77.6 years) compared to 54.8 years for UE patients and 54.1 years in LE patients (p<0.001). HP patients also had the highest average ASA score (3.0) (p<0.001). There was a significant difference in adverse cardiac events based on anatomic area: 0.27% (32/11,905) UE patients developed cardiac complications compared to 2.15% (623/29,009) HP patients and 0.61% (94/15,422) LE patients. After multivariate analysis, HP patients were significantly more likely to develop cardiac complications compared to both UE patients (OR: 6.377, p=0.014) and LE patients (OR: 2.766, p=0.009). There is a significant difference in adverse cardiac events following orthopaedic trauma based on anatomic region. Hip/Pelvis surgery appeared to be a significant risk factor in developing an adverse cardiac event. Further studies should investigate why hip/pelvic patients are at a higher risk of adverse cardiac events. Copyright © 2016 Elsevier Ltd. All rights reserved.

An initial study on the estimation of time-varying volumetric treatment images and 3D tumor localization from single MV cine EPID images

PubMed Central

Mishra, Pankaj; Li, Ruijiang; Mak, Raymond H.; Rottmann, Joerg; Bryant, Jonathan H.; Williams, Christopher L.; Berbeco, Ross I.; Lewis, John H.

2014-01-01

Purpose: In this work the authors develop and investigate the feasibility of a method to estimate time-varying volumetric images from individual MV cine electronic portal image device (EPID) images. Methods: The authors adopt a two-step approach to time-varying volumetric image estimation from a single cine EPID image. In the first step, a patient-specific motion model is constructed from 4DCT. In the second step, parameters in the motion model are tuned according to the information in the EPID image. The patient-specific motion model is based on a compact representation of lung motion represented in displacement vector fields (DVFs). DVFs are calculated through deformable image registration (DIR) of a reference 4DCT phase image (typically peak-exhale) to a set of 4DCT images corresponding to different phases of a breathing cycle. The salient characteristics in the DVFs are captured in a compact representation through principal component analysis (PCA). PCA decouples the spatial and temporal components of the DVFs. Spatial information is represented in eigenvectors and the temporal information is represented by eigen-coefficients. To generate a new volumetric image, the eigen-coefficients are updated via cost function optimization based on digitally reconstructed radiographs and projection images. The updated eigen-coefficients are then multiplied with the eigenvectors to obtain updated DVFs that, in turn, give the volumetric image corresponding to the cine EPID image. Results: The algorithm was tested on (1) Eight digital eXtended CArdiac-Torso phantom datasets based on different irregular patient breathing patterns and (2) patient cine EPID images acquired during SBRT treatments. The root-mean-squared tumor localization error is (0.73 ± 0.63 mm) for the XCAT data and (0.90 ± 0.65 mm) for the patient data. Conclusions: The authors introduced a novel method of estimating volumetric time-varying images from single cine EPID images and a PCA-based lung motion model. This is the first method to estimate volumetric time-varying images from single MV cine EPID images, and has the potential to provide volumetric information with no additional imaging dose to the patient. PMID:25086523

An initial study on the estimation of time-varying volumetric treatment images and 3D tumor localization from single MV cine EPID images

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mishra, Pankaj, E-mail: pankaj.mishra@varian.com; Mak, Raymond H.; Rottmann, Joerg

2014-08-15

Purpose: In this work the authors develop and investigate the feasibility of a method to estimate time-varying volumetric images from individual MV cine electronic portal image device (EPID) images. Methods: The authors adopt a two-step approach to time-varying volumetric image estimation from a single cine EPID image. In the first step, a patient-specific motion model is constructed from 4DCT. In the second step, parameters in the motion model are tuned according to the information in the EPID image. The patient-specific motion model is based on a compact representation of lung motion represented in displacement vector fields (DVFs). DVFs are calculatedmore » through deformable image registration (DIR) of a reference 4DCT phase image (typically peak-exhale) to a set of 4DCT images corresponding to different phases of a breathing cycle. The salient characteristics in the DVFs are captured in a compact representation through principal component analysis (PCA). PCA decouples the spatial and temporal components of the DVFs. Spatial information is represented in eigenvectors and the temporal information is represented by eigen-coefficients. To generate a new volumetric image, the eigen-coefficients are updated via cost function optimization based on digitally reconstructed radiographs and projection images. The updated eigen-coefficients are then multiplied with the eigenvectors to obtain updated DVFs that, in turn, give the volumetric image corresponding to the cine EPID image. Results: The algorithm was tested on (1) Eight digital eXtended CArdiac-Torso phantom datasets based on different irregular patient breathing patterns and (2) patient cine EPID images acquired during SBRT treatments. The root-mean-squared tumor localization error is (0.73 ± 0.63 mm) for the XCAT data and (0.90 ± 0.65 mm) for the patient data. Conclusions: The authors introduced a novel method of estimating volumetric time-varying images from single cine EPID images and a PCA-based lung motion model. This is the first method to estimate volumetric time-varying images from single MV cine EPID images, and has the potential to provide volumetric information with no additional imaging dose to the patient.« less