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1

Four-dimensional magnetic resonance imaging (4D-MRI) using image-based respiratory surrogate: A feasibility study  

PubMed Central

Purpose: Four-dimensional computed tomography (4D-CT) has been widely used in radiation therapy to assess patient-specific breathing motion for determining individual safety margins. However, it has two major drawbacks: low soft-tissue contrast and an excessive imaging dose to the patient. This research aimed to develop a clinically feasible four-dimensional magnetic resonance imaging (4D-MRI) technique to overcome these limitations. Methods: The proposed 4D-MRI technique was achieved by continuously acquiring axial images throughout the breathing cycle using fast 2D cine-MR imaging, and then retrospectively sorting the images by respiratory phase. The key component of the technique was the use of body area (BA) of the axial MR images as an internal respiratory surrogate to extract the breathing signal. The validation of the BA surrogate was performed using 4D-CT images of 12 cancer patients by comparing the respiratory phases determined using the BA method to those determined clinically using the Real-time position management (RPM) system. The feasibility of the 4D-MRI technique was tested on a dynamic motion phantom, the 4D extended Cardiac Torso (XCAT) digital phantom, and two healthy human subjects. Results: Respiratory phases determined from the BA matched closely to those determined from the RPM: mean (±SD) difference in phase:??3.9% (±6.4%); mean (±SD) absolute difference in phase: 10.40% (±3.3%); mean (±SD) correlation coefficient: 0.93 (±0.04). In the motion phantom study, 4D-MRI clearly showed the sinusoidal motion of the phantom; image artifacts observed were minimal to none. Motion trajectories measured from 4D-MRI and 2D cine-MRI (used as a reference) matched excellently: the mean (±SD) absolute difference in motion amplitude:??0.3 (±0.5) mm. In the 4D-XCAT phantom study, the simulated “4D-MRIimages showed good consistency with the original 4D-XCAT phantom images. The motion trajectory of the hypothesized “tumor” matched excellently between the two, with a mean (±SD) absolute difference in motion amplitude of 0.5 (±0.4) mm. 4D-MRI was able to reveal the respiratory motion of internal organs in both human subjects; superior–inferior (SI) maximum motion of the left kidney of Subject #1 and the diaphragm of Subject #2 measured from 4D-MRI was 0.88 and 1.32 cm, respectively. Conclusions: Preliminary results of our study demonstrated the feasibility of a novel retrospective 4D-MRI technique that uses body area as a respiratory surrogate. PMID:22149822

Cai, Jing; Chang, Zheng; Wang, Zhiheng; Paul Segars, William; Yin, Fang-Fang

2011-01-01

2

Diffusion Microscopist Simulator: A General Monte Carlo Simulation System for Diffusion Magnetic Resonance Imaging  

PubMed Central

This article describes the development and application of an integrated, generalized, and efficient Monte Carlo simulation system for diffusion magnetic resonance imaging (dMRI), named Diffusion Microscopist Simulator (DMS). DMS comprises a random walk Monte Carlo simulator and an MR image synthesizer. The former has the capacity to perform large-scale simulations of Brownian dynamics in the virtual environments of neural tissues at various levels of complexity, and the latter is flexible enough to synthesize dMRI datasets from a variety of simulated MRI pulse sequences. The aims of DMS are to give insights into the link between the fundamental diffusion process in biological tissues and the features observed in dMRI, as well as to provide appropriate ground-truth information for the development, optimization, and validation of dMRI acquisition schemes for different applications. The validity, efficiency, and potential applications of DMS are evaluated through four benchmark experiments, including the simulated dMRI of white matter fibers, the multiple scattering diffusion imaging, the biophysical modeling of polar cell membranes, and the high angular resolution diffusion imaging and fiber tractography of complex fiber configurations. We expect that this novel software tool would be substantially advantageous to clarify the interrelationship between dMRI and the microscopic characteristics of brain tissues, and to advance the biophysical modeling and the dMRI methodologies. PMID:24130783

Yeh, Chun-Hung; Schmitt, Benoît; Le Bihan, Denis; Li-Schlittgen, Jing-Rebecca; Lin, Ching-Po; Poupon, Cyril

2013-01-01

3

A new method for joint susceptibility artefact correction and super-resolution for dMRI  

NASA Astrophysics Data System (ADS)

Diffusion magnetic resonance imaging (dMRI) has become increasingly relevant in clinical research and neuroscience. It is commonly carried out using the ultra-fast MRI acquisition technique Echo-Planar Imaging (EPI). While offering crucial reduction of acquisition times, two limitations of EPI are distortions due to varying magnetic susceptibilities of the object being imaged and its limited spatial resolution. In the recent years progress has been made both for susceptibility artefact correction and increasing of spatial resolution using image processing and reconstruction methods. However, so far, the interplay between both problems has not been studied and super-resolution techniques could only be applied along one axis, the slice-select direction, limiting the potential gain in spatial resolution. In this work we describe a new method for joint susceptibility artefact correction and super-resolution in EPI-MRI that can be used to increase resolution in all three spatial dimensions and in particular increase in-plane resolutions. The key idea is to reconstruct a distortion-free, high-resolution image from a number of low-resolution EPI data that are deformed in different directions. Numerical results on dMRI data of a human brain indicate that this technique has the potential to provide for the first time in-vivo dMRI at mesoscopic spatial resolution (i.e. 500?m) a spatial resolution that could bridge the gap between white-matter information from ex-vivo histology (?1?m) and in-vivo dMRI (?2000?m).

Ruthotto, Lars; Mohammadi, Siawoosh; Weiskopf, Nikolaus

2014-03-01

4

Quantitative magnetic resonance imaging of brain development in premature and mature newborns  

Microsoft Academic Search

Definition in the living premature infant of the anatomical and temporal characteristics of development of critical brain structures is crucial for insight into the time of greatest vulnerability of such brain structures. We utilized 3D Magnetic Resonance Imaging (3D-MRI) and image processing algorithms to quantitate total brain volume and total volumes of cerebral gray matter (GM), unmyelinated white matter (WM),

Simon Warfield; Ron Kikinis; Patrick D. Barnes; Gary P. Zientara; Ferenc A. Jolesz; Miles K. Tsuji; Joseph J. Volpe

1998-01-01

5

Comparative mouse brain tractography of diffusion magnetic resonance imaging  

PubMed Central

Diffusion magnetic resonance imaging (dMRI) tractography can be employed to simultaneously analyse three-dimensional white matter tracts in the brain. Numerous methods have been proposed to model diffusion-weighted magnetic resonance data for tractography, and we have explored the functionality of some of these for studying white and grey matter pathways in ex vivo mouse brain. Using various deterministic and probabilistic algorithms across a range of regions of interest we found that probabilistic tractography provides a more robust means of visualizing both white and grey matter pathways than deterministic tractography. Importantly, we demonstrate the sensitivity of probabilistic tractography profiles to streamline number, step size, curvature, fiber orientation distribution, and whole-brain versus region of interest seeding. Using anatomically well-defined cortico-thalamic pathways, we show how density maps can permit the topographical assessment of probabilistic tractography. Finally, we show how different tractography approaches can impact on dMRI assessment of tract changes in a mouse deficient for the frontal cortex morphogen, fibroblast growth factor 17. In conclusion, probabilistic tractography can elucidate the phenotypes of mice with neurodegenerative or neurodevelopmental disorders in a quantitative manner. PMID:20303410

Moldrich, Randal X.; Pannek, Kerstin; Hoch, Renee; Rubenstein, John L.; Kurniawan, Nyoman D.; Richards, Linda J.

2010-01-01

6

Dynamic kine magnetic resonance imaging in whiplash patients and in age- and sex-matched controls.  

PubMed

The multitude of symptoms following a whiplash injury has given rise to much discussion because of the lack of objective radiological findings. The ligaments that stabilize the upper cervical spine can be injured. Dynamic kine magnetic resonance imaging (dMRI) may reveal the pathological motion patterns caused by injury to these ligaments. To compare the findings and motion patterns in the upper cervical spine, 25 whiplash trauma patients with longstanding pain, limb symptoms and loss of balance indicating a problem at the level of C0-C2, as well as matched healthy controls were imaged using dMRI. Imaging was performed with an Intera 1.5 T (Philips Healthcare, USA) magnet. A physiotherapist performed the bending and rotation of the upper cervical spine for the subjects to ensure that the movements were limited to the C0-C2 level. An oblique coronal T2- and proton density-weighted sequence and a balanced fast field echo axial sequence were used. The movements between C0-C2 and the signal from the alar ligaments were analyzed. Contact of the transverse ligament and the medulla in rotation was seen in two patients. The signal from the alar ligaments was abnormal in 92% of the patients and in 24% of the control subjects (P<0.0001). Abnormal movements at the level of C1-C2 were more common in patients than in controls (56% versus 20%, P=0.028). Whiplash patients with longstanding symptoms had both more abnormal signals from the alar ligaments and more abnormal movements on dMRI at the C0-C2 level than controls. PMID:20011712

Lindgren, Karl-August; Kettunen, J A; Paatelma, M; Mikkonen, R H M

2009-01-01

7

Magnetic resonance imaging  

SciTech Connect

The authors present a review of magnetic resonance imaging. Many topics are explored from instrumentation, spectroscopy, blood flow and sodium imaging to detailed clinical applications such as the differential diagnosis of multiple sclerosis or adrenal adenoma. The emphasis throughout is on descriptions of normal multiplanar anatomy and pathology as displayed by MRI.

Stark, D.D.; Bradley, W.G. Jr.

1988-01-01

8

Functional Magnetic Resonance Imaging  

ERIC Educational Resources Information Center

Functional magnetic resonance imaging (fMRI), with its excellent spatial resolution and ability to visualize networks of neuroanatomical structures involved in complex information processing, has become the dominant technique for the study of brain function and its development. The accessibility of in-vivo pediatric brain-imaging techniques…

Voos, Avery; Pelphrey, Kevin

2013-01-01

9

Magnetic Resonance Imaging  

PubMed Central

Magnetic resonance imaging (MRI) is an important new imaging modality just arriving on the clinical scene in Canada. MRI uses no ionizing radiation; images are derived from the interaction of hydrogen nuclei, a powerful magnetic field, and radio waves. Images are displayed as tomographic slices, much like CT. Direct transverse, sagittal, coronal or oblique slices can be obtained. Unlike CT, the MRI image does not reflect varying tissue densities. In MRI, tissues are differentiated by variation in the amount of hydrogen they contain and by differences in the magnetic environment at a molecular level. All parts of the body can be examined with MRI, although the CNS is particularly well visualized. In addition to providing high resolution images, MRI has the potential for performing non-invasive angiography and biochemical analysis through spectroscopy. To date, there are no known harmful effects of MRI. ImagesFigure 1Figure 2Figure 3Figure 4Figure 5 PMID:21267205

Fache, J. Stephen

1986-01-01

10

Magnetic Resonance Imaging  

NSDL National Science Digital Library

This lesson ties the preceding lessons together and brings students back to the grand challenge question on MRI safety. During this lesson, students focus on the logistics of magnetic resonance imaging as well as the MRI hardware. Students can then integrate this knowledge with their acquired knowledge on magnetic fields to solve the challenge question.

VU Bioengineering RET Program, School of Engineering,

11

Clinical magnetic resonance imaging  

SciTech Connect

This book presents clinical applications of magnetic resonance imaging with a strong clinical orientation. Covers technique, instrumentation, and contrast agents. Describes MRI of the neck, brain, heart, spine, TMJ and orbit, chest abdomen, pelvis, and the joints. Also includes a high field atlas of the central nervous system.

Brady, T.J.; Edelman, R.R.

1988-01-01

12

Introduction Magnetic Resonance Imaging (MRI)  

E-print Network

Introduction Statistics Magnetic Resonance Imaging (MRI) Statistics in the UK Statistics at UCL and Beyond #12;Introduction Statistics Magnetic Resonance Imaging (MRI) Statistics in the UK Statistics Magnetic Resonance Imaging (MRI) Statistics in the UK Statistics at UCL Outline Why do Statistics? Some

Wirosoetisno, Djoko

13

Interventional magnetic resonance imaging.  

PubMed

The development of minimally invasive surgical and interventional techniques has created a need for more accurate and sensitive image guidance and monitoring. Magnetic resonance imaging, with its superior soft tissue discrimination and multiplanar facilities, seems the obvious choice for an ideal image-guidance tool. Until recently, the employment of MRI in this role has been prevented by the physical constraints of conventional, closed-configuration machines. The problem has now been overcome by the development of an open design allowing both horizontal and vertical access to the patient in the scanner so that procedures can be performed concurrent with image acquisition. This configuration, together with the use of fast gradient echo sequences which can scan at speeds close to real time, means that a wide range of interventional procedures can be performed with on-line image guidance and monitoring. In addition, the versatility of the open design means that patients can assume physiological positions to allow dynamic joint imaging to be performed. This opens up a whole new field in the understanding of joint pathophysiology. This review article discusses these recent technological developments and their clinical applications. In particular, the potential role in guidance of biopsies, monitoring of thermal ablation techniques and applications in endoscopic surgery is outlined. PMID:9534721

Lamb, G M; Gedroyc, W M

1997-11-01

14

Diffusion MRI simulation with the Virtual Imaging Platform Lihui Wang, Sorina Camarasu-Pop, Tristan Glatard, Yue-Min Zhu, Isabelle E. Magnin  

E-print Network

1 Diffusion MRI simulation with the Virtual Imaging Platform Lihui Wang, Sorina Camarasu of in vivo human heart. Diffusion magnetic resonance imaging (dMRI) is one of the most potential techniques and with influence of MRI scanner noise and artifacts, it is difficult to evaluate how well the diffusion

Paris-Sud XI, Université de

15

Parallel magnetic resonance imaging: characterization and comparison  

E-print Network

Magnetic Resonance Imaging (MRI) is now increasingly being used for fast imaging applications such as real-time cardiac imaging, functional brain imaging, contrast enhanced MRI, etc. Imaging speed in MRI is mainly limited by different imaging...

Rane, Swati Dnyandeo

2005-11-01

16

Breast magnetic resonance imaging  

Microsoft Academic Search

Breast MRI is becoming an important tool for the improved management of breast cancer. The technical attributes of high contrast, high-resolution breast MRI acquisitions are summarized. The fundamentals of image interpretation are outlined, including lesion enhancement, morphological features, and extent categories. The indications for breast MRI include compromised mammography, staging of disease within the breast and adjacent structures, difficult histology,

Steven E Harms

1998-01-01

17

Magnetic resonance imaging of electrolysis.  

PubMed

This study explores the hypothesis that Magnetic Resonance Imaging (MRI) can image the process of electrolysis by detecting pH fronts. The study has relevance to real time control of cell ablation with electrolysis. To investigate the hypothesis we compare the following MR imaging sequences: T1 weighted, T2 weighted and Proton Density (PD), with optical images acquired using pH-sensitive dyes embedded in a physiological saline agar solution phantom treated with electrolysis and discrete measurements with a pH microprobe. We further demonstrate the biological relevance of our work using a bacterial E. Coli model, grown on the phantom. The results demonstrate the ability of MRI to image electrolysis produced pH changes in a physiological saline phantom and show that these changes correlate with cell death in the E. Coli model grown on the phantom. The results are promising and invite further experimental research. PMID:25659942

Meir, Arie; Hjouj, Mohammad; Rubinsky, Liel; Rubinsky, Boris

2015-01-01

18

Magnetic Resonance Imaging of Electrolysis.  

PubMed Central

This study explores the hypothesis that Magnetic Resonance Imaging (MRI) can image the process of electrolysis by detecting pH fronts. The study has relevance to real time control of cell ablation with electrolysis. To investigate the hypothesis we compare the following MR imaging sequences: T1 weighted, T2 weighted and Proton Density (PD), with optical images acquired using pH-sensitive dyes embedded in a physiological saline agar solution phantom treated with electrolysis and discrete measurements with a pH microprobe. We further demonstrate the biological relevance of our work using a bacterial E. Coli model, grown on the phantom. The results demonstrate the ability of MRI to image electrolysis produced pH changes in a physiological saline phantom and show that these changes correlate with cell death in the E. Coli model grown on the phantom. The results are promising and invite further experimental research. PMID:25659942

Meir, Arie; Hjouj, Mohammad; Rubinsky, Liel; Rubinsky, Boris

2015-01-01

19

Interventional Cardiovascular Magnetic Resonance Imaging  

PubMed Central

Cardiovascular magnetic resonance (CMR) combines excellent soft-tissue contrast, multiplanar views, and dynamic imaging of cardiac function without ionizing radiation exposure. Interventional cardiovascular magnetic resonance (iCMR) leverages these features to enhance conventional interventional procedures or to enable novel ones. Although still awaiting clinical deployment, this young field has tremendous potential. We survey promising clinical applications for iCMR. Next, we discuss the technologies that allow CMR-guided interventions and, finally, what still needs to be done to bring them to the clinic. PMID:19909937

Saikus, Christina E.; Lederman, Robert J.

2010-01-01

20

Magnetic Resonance Imaging and Magnetic Resonance Spectroscopy in Dementias  

PubMed Central

This article reviews recent studies of magnetic resonance imaging and magnetic resonance spectroscopy in dementia, including Alzheimer's disease, frontotemporal dementia, dementia with Lewy bodies, idiopathic Parkinson's disease, Huntington's disease, and vascular dementia. Magnetic resonance imaging and magnetic resonance spectroscopy can detect structural alteration and biochemical abnormalities in the brain of demented subjects and may help in the differential diagnosis and early detection of affected individuals, monitoring disease progression, and evaluation of therapeutic effect. PMID:11563438

Hsu, Yuan-Yu; Du, An-Tao; Schuff, Norbert; Weiner, Michael W.

2007-01-01

21

Interventional cardiovascular magnetic resonance imaging  

PubMed Central

Magnetic resonance imaging (MRI) provides structural and functional cardiovascular information with excellent soft tissue contrast. Real-time MRI can guide transcatheter cardiovascular interventions in large animal models, and may prove superior to x-ray and adjunct modalities for peripheral vascular, structural heart and cardiac electrophysiology applications. We describe technical considerations, pre-clinical work and early clinical studies in this emerging field. PMID:17662914

Raman, Venkatesh K.; Lederman, Robert J.

2008-01-01

22

[Cardiac magnetic resonance imaging (MRI)].  

PubMed

TECHNOLOGICAL PROGRESS: Although cardiac magnetic resonance imaging (MRI) is now recognised as the imaging method of choice for the morphological study of the heart, recent technological progress have widened its indications to functional analysis of the heart rate, perfusion and contractility. FUNCTIONAL ASSESSMENT: The possibility of conducting pharmacological stress tests enhances the functional exploration of cardiac perfusion and contractility. The rapid sequences in apnea, tissue marking and injection of contrast products are all elements that help to refine the study of the locoregional consequences of an ischemia: does the myocardial tissue contract normally? Is it sufficiently perfused? Is it still viable? THE BENEFITS OF A NON-INVASIVE TECHNIQUE: The MRI offers clinicians a non-invasive and non-radiating imaging technique that is the perfect supplement to echocardiography. A reliable angio-coronary LRI technique would, for the first time, permit exploration of the coronary vascularisation, tissue perfusion and resulting contractility. PMID:15387389

Vignaux, Olivier

2004-07-31

23

[Magnetic resonance imaging of the breasts].  

PubMed

Not even magnetic resonance imaging is a perfect method for imaging of the breasts. Quality of the equipment, imaging parameters as well as the experience and competence of radiographers and radiologists have a significant effect on the final outcome of the study. Since interpretation of magnetic resonance imaging of the breasts is challenging, the radiologist should have access to a comprehensive medical history and previous images, including the reports. Feedback from the reports made and multidisciplinary postoperative meetings are important. Since magnetic resonance imaging is expensive and has low availability, it should be targeted at the correct patient groups. PMID:24340717

Hukkinen, Katja

2013-01-01

24

Prenatal Imaging: Ultrasonography and Magnetic Resonance Imaging  

PubMed Central

The Eunice Kennedy Shriver National Institute of Child Health and Human Development held a workshop on September 18–19, 2006, to summarize the available evidence on the role and performance of current fetal imaging technology and to establish a research agenda. Ultrasonography is the imaging modality of choice for pregnancy evaluation due to its relatively low cost, real-time capability, safety, and operator comfort and experience. First-trimester ultrasonography extends the available window for fetal observation and raises the possibility of performing an early anatomic survey. Three-dimensional ultrasonography has the potential to expand the clinical application of ultrasonography by permitting local acquisition of volumes and remote review and interpretation at specialized centers. New advances allow performance of fetal magnetic resonance imaging (MRI) without maternal or fetal sedation, with improved characterization and prediction of prognosis of certain fetal central nervous system anomalies such as ventriculomegaly when compared with ultrasonography. Fewer data exist on the usefulness of fetal MRI for non–central nervous system anomalies. PMID:18591320

Reddy, Uma M.; Filly, Roy A.; Copel, Joshua A.

2009-01-01

25

Investigating the capability to resolve complex white matter structures with high b-value diffusion magnetic resonance imaging on the MGH-USC Connectom scanner.  

PubMed

One of the major goals of the NIH Blueprint Human Connectome Project was to map and quantify the white matter connections in the brain using diffusion tractography. Given the prevalence of complex white matter structures, the capability of resolving local white matter geometries with multiple crossings in the diffusion magnetic resonance imaging (dMRI) data is critical. Increasing b-value has been suggested for delineation of the finer details of the orientation distribution function (ODF). Although increased gradient strength and duration increase sensitivity to highly restricted intra-axonal water, gradient strength limitations require longer echo times (TE) to accommodate the increased diffusion encoding times needed to achieve a higher b-value, exponentially lowering the signal-to-noise ratio of the acquisition. To mitigate this effect, the MGH-USC Connectom scanner was built with 300 mT/m gradients, which can significantly reduce the TE of high b-value diffusion imaging. Here we report comparisons performed across b-values based on q-ball ODF metrics to investigate whether high b-value diffusion imaging on the Connectom scanner can improve resolving complex white matter structures. The q-ball ODF features became sharper as the b-value increased, with increased power fraction in higher order spherical harmonic series of the ODF and increased peak heights relative to the overall size of the ODF. Crossing structures were detected in an increasingly larger fraction of white matter voxels and the spatial distribution of two-way and three-way crossing structures was largely consistent with known anatomy. Results indicate that dMRI with high diffusion encoding on the Connectom system is a promising tool to better characterize, and ultimately understand, the underlying structural organization and motifs in the human brain. PMID:25287963

Fan, Qiuyun; Nummenmaa, Aapo; Witzel, Thomas; Zanzonico, Roberta; Keil, Boris; Cauley, Stephen; Polimeni, Jonathan R; Tisdall, Dylan; Van Dijk, Koene R A; Buckner, Randy L; Wedeen, Van J; Rosen, Bruce R; Wald, Lawrence L

2014-11-01

26

Gradient characterization in magnetic resonance imaging  

E-print Network

Special magnetic resonance (MR) scans, such as spiral imaging and echo-planar imaging, require speed and gradient accuracy while putting high demands on the MR gradient system that may cause gradient distortion. Additionally, ...

Cheng, Joseph Yitan

2007-01-01

27

Magnetic resonance images in hanging.  

PubMed

Hanging is a devastating method of suicide and unfortunately is common in Japan. Although several CT findings of the head have been reported, there have not been any reports about magnetic resonance imaging (MRI) in hanging. We report here interesting MRI findings in a patient after hanging. A 39-year-old woman was transferred to our department after attempting suicide by hanging. Respiration had probably ceased for about three minutes but heart had not stopped when she was pulled down by her father. After her father performed cardiopulmonary resuscitation, she started to breathe immediately. She was treated conservatively in our intensive care unit for 14 days, her condition became stable. Ten days after admission, MRI demonstrated symmetrical hyperintensity on T1-weighted images and relative hyperintensity on T2 weighted images in bilateral lentiform nuclei and medial thalami. There have been several reports about characteristic MRI findings in the case of acute global cerebral ischaemia caused by severe hypoglycaemia or longstanding cardiopulmonary arrest. It was postulated that these specific findings reflected tissue degeneration, deposition of mineral substances, or lipid accumulation. These MRI findings suggest that severe acute global cerebral hypoperfusion also occurs in hanging in the same way as in long-standing cardiopulmonary arrest and that hanging has devastating sequelae. PMID:16458413

Matsuyama, Takeshi; Okuchi, Kazuo; Seki, Tadahiko; Higuchi, Takafumi; Ito, Shingo; Makita, Daisuke; Watanabe, Tomoo; Murao, Yoshinori

2006-05-01

28

Essential physics of nuclear acoustic resonance imaging  

Microsoft Academic Search

Nuclear acoustic resonance (NAR), like nuclear magnetic resonance (NMR), can be used as a spectroscopic imaging tool to detect and characterize soft tissue densities and differences on the atomic scale. Whereas NMR uses electromagnetic radiation to induce energy level transitions, NAR uses acoustic radiation. The frequency of this radiation is typically 1 to 100 MHz; NAR imaging therefore uses ultrasonic

Ross M. Henderson

1997-01-01

29

Polarimetric surface plasmon resonance imaging biosensor  

E-print Network

Polarimetric surface plasmon resonance imaging biosensor Aurélien Duval,1, * Aude Laisné,2 Denis.6680, 310.6860, 110.5405. Surface plasmon resonance (SPR) biosensors are be- ing increasingly used of capturing TM-polarized images of the biosensor's surface, fol- lowing two orthogonal planes of incidence

Paris-Sud XI, Université de

30

Can Dynamic MR Imaging Predict Response in Patients with Rectal Cancer Undergoing Cetuximab-Based Neoadjuvant Chemoradiation?  

Microsoft Academic Search

SummaryBackground: The aim of this study was to evaluate therapy response in patients undergoing cetuximab-CapIri-based chemoradiation for rectal cancer using dynamic magnetic resonance imaging (dMRI). Patients and Methods: The volumetric degree of tumor regression and contrast media perfusion were compared to the results of the histopathologic ypTN staging. 33 patients were examined using a 1.5-T scanner with repetitive 2D FLASH

Dietmar J. Dinter; Karoline Horisberger; Christian Zechmann; Frederik Wenz; Joachim Brade; Frank Willeke; K. Wolfgang Neff; Stefan O. Schoenberg; Ralf-Dieter Hofheinz

2009-01-01

31

Imaging agents for in vivo magnetic resonance and scintigraphic imaging  

DOEpatents

Methods are provided for in vivo magnetic resonance imaging and/or scintigraphic imaging of a subject using chelated transition metal and lanthanide metal complexes. Novel ligands for these complexes are provided.

Engelstad, Barry L. (Orinda, CA); Raymond, Kenneth N. (Berkeley, CA); Huberty, John P. (Corte Madera, CA); White, David L. (Oakland, CA)

1991-01-01

32

Imaging agents for in vivo magnetic resonance and scintigraphic imaging  

DOEpatents

Methods are provided for in vivo magnetic resonance imaging and/or scintigraphic imaging of a subject using chelated transition metal and lanthanide metal complexes. Novel ligands for these complexes are provided. No Drawings

Engelstad, B.L.; Raymond, K.N.; Huberty, J.P.; White, D.L.

1991-04-23

33

Magnetic resonance imaging in cardiovascular disease   

E-print Network

Background Superparamagnetic particles of iron oxide (SPIO) are part of a novel and exciting class of ‘smart’ magnetic resonance imaging (MRI) contrast agents that are taken up by inflammatory cells. Ultrasmall SPIO ...

Richards, Jennifer Margaret Jane

2013-07-06

34

Coronary Computed Tomography and Magnetic Resonance Imaging  

PubMed Central

Cardiac computed tomography and magnetic resonance are relatively new imaging modalities that can exceed the ability of established imaging modalities to detect present pathology or predict patient outcomes. Coronary calcium scoring may be useful in asymptomatic patients at intermediate risk. Computed tomographic coronary angiography is a first-line indication to evaluate congenitally abnormal coronary arteries and, along with stress magnetic resonance myocardial perfusion imaging, is useful in symptomatic patients with nondiagnostic conventional stress tests. Cardiac magnetic resonance is indicated for visualizing cardiac structure and function, and delayed enhancement magnetic resonance is a first-line indication for assessing myocardial viability. Imaging plaque and molecular mechanisms related to plaque rupture holds great promise for the presymptomatic detection of patients at risk for coronary events but is not yet suitable for routine clinical use. PMID:19269527

Kantor, Birgit; Nagel, Eike; Schoenhagen, Paul; Barkhausen, Jörg; Gerber, Thomas C.

2009-01-01

35

PANDA: a pipeline toolbox for analyzing brain diffusion images.  

PubMed

Diffusion magnetic resonance imaging (dMRI) is widely used in both scientific research and clinical practice in in-vivo studies of the human brain. While a number of post-processing packages have been developed, fully automated processing of dMRI datasets remains challenging. Here, we developed a MATLAB toolbox named "Pipeline for Analyzing braiN Diffusion imAges" (PANDA) for fully automated processing of brain diffusion images. The processing modules of a few established packages, including FMRIB Software Library (FSL), Pipeline System for Octave and Matlab (PSOM), Diffusion Toolkit and MRIcron, were employed in PANDA. Using any number of raw dMRI datasets from different subjects, in either DICOM or NIfTI format, PANDA can automatically perform a series of steps to process DICOM/NIfTI to diffusion metrics [e.g., fractional anisotropy (FA) and mean diffusivity (MD)] that are ready for statistical analysis at the voxel-level, the atlas-level and the Tract-Based Spatial Statistics (TBSS)-level and can finish the construction of anatomical brain networks for all subjects. In particular, PANDA can process different subjects in parallel, using multiple cores either in a single computer or in a distributed computing environment, thus greatly reducing the time cost when dealing with a large number of datasets. In addition, PANDA has a friendly graphical user interface (GUI), allowing the user to be interactive and to adjust the input/output settings, as well as the processing parameters. As an open-source package, PANDA is freely available at http://www.nitrc.org/projects/panda/. This novel toolbox is expected to substantially simplify the image processing of dMRI datasets and facilitate human structural connectome studies. PMID:23439846

Cui, Zaixu; Zhong, Suyu; Xu, Pengfei; He, Yong; Gong, Gaolang

2013-01-01

36

Magnetic resonance imaging of the thorax  

SciTech Connect

Magnetic Resonance Imaging of the Thorax is an introductory text covering magnetic resources (MR) imaging of the heart, great vessels, mediastinum, hili, pulmonary nodules, pleura, and diaphragm. The book opens with a brief discussion of MR physics. This is followed by a larger section on normal mediastinal anatomy as viewed on axial, coronal, and sagittal MR images. This chapter suffers form several poor-quality images and inadequate labeling. The last section gives 13 cases for review and self-testing.

Sperber, M.; Kaiser, M.C.

1987-01-01

37

Chapter 20. Magnetic Resonance Imaging Magnetic Resonance Imaging  

E-print Network

, and students who are associated with MIT and with the HST Athinoula A. Martinos Center for Biomedical Imaging; equipment support from the Athinoula A. Martinos Center for Biomedical Imaging; HST Martinos Catalyst Fund for Biomedical Imaging at Massachusetts General Hospital (MGH) and the Harvard-MIT Division of Health Sciences

38

STROBOSCOPIC ARTICULOGRAPHY USING FAST MAGNETIC RESONANCE IMAGING  

Microsoft Academic Search

A method to display dynamic aspects of vocal tract configuration during speech production by means of fast magnetic resonance imaging (MRI) is presented. Data acquisition during repetitive movement relies on a stroboscopy-like procedure. The time res- olution achieved is 120 images per second in a selected plane. As compared to other techniques of kinematic measurements of speech motor processes, this

K. Mathiak; U. Klose; H. Ackermann; I. Hertrich; W.-E. Kincses; W. Grodd

39

Brain Morphometry Using Anatomical Magnetic Resonance Imaging  

ERIC Educational Resources Information Center

The efficacy of anatomical magnetic resonance imaging (MRI) in studying the morphological features of various regions of the brain is described, also providing the steps used in the processing and studying of the images. The ability to correlate these features with several clinical and psychological measures can help in using anatomical MRI to…

Bansal, Ravi; Gerber, Andrew J.; Peterson, Bradley S.

2008-01-01

40

Magnetic resonance imaging in prostate cancer  

Microsoft Academic Search

With the recently published National Institute of Clinical Excellence guidelines, it is now generally accepted that magnetic resonance imaging (MRI) is the imaging method of choice for staging prostate cancer in patients for whom radical treatment is being considered. MRI offers the single most accurate assessment of local disease and regional metastatic spread. As well as detecting extraprostatic extension, this

S D Heenan

2004-01-01

41

Simple and Inexpensive Classroom Demonstrations of Nuclear Magnetic Resonance and Magnetic Resonance Imaging.  

ERIC Educational Resources Information Center

Describes a set of simple, inexpensive, classical demonstrations of nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) principles that illustrate the resonance condition associated with magnetic dipoles and the dependence of the resonance frequency on environment. (WRM)

Olson, Joel A.; Nordell, Karen J.; Chesnik, Marla A.; Landis, Clark R.; Ellis, Arthur B.; Rzchowski, M. S.; Condren, S. Michael; Lisensky, George C.

2000-01-01

42

Magnetic Resonance Imaging (MRI) -- Head  

MedlinePLUS Videos and Cool Tools

... and the possible charges that you will incur. Web page review process: This Web page is reviewed regularly by a physician with ... not responsible for the content contained on the web pages found at these links. Images: Images are ...

43

Magnetic resonance imaging of the body  

SciTech Connect

This text provides reference to magnetic resonance imaging (MRI) of the body. Beginning with explanatory chapters on the physics, instrumentation, and interpretation of MRI, it proceeds to the normal anatomy of the neck, thorax, abdomen, and pelvis. Other chapters cover magnetic resonance imaging of blood flow, the larynx, the lymph nodes, and the spine, as well as MRI in obstetrics. The text features detailed coverage of magnetic resonance imaging of numerous disorders and disease states, including neck disease, thoracic disease; breast disease; congenital and acquired heart disease; vascular disease; diseases of the liver, pancreas, and spleen; diseases of the kidney, adrenals, and retroperitoneum; diseases of the male and female pelvis; and musculoskeletal diseases. Chapters on the biological and environmental hazards of MRI, the current clinical status of MRI in comparison to other imaging modalities, and economic considerations are also included.

Higgins, C.B.; Hricak, H.

1987-01-01

44

Cardiac magnetic resonance imaging: artefacts for clinicians.  

PubMed

In recent years, the clinical importance of cardiac magnetic resonance (CMR) imaging has increased dramatically. As a consequence, more clinicians need to become familiar with this imaging modality, including its technical challenges. MR images are obtained through a physical process of proton excitation and the reception of resonating signals. Besides these physical principles, the motion of the heart and diaphragm, together with the presence of fast flowing blood in the vicinity, pose challenges to the acquisition of high-quality diagnostic images and are an important cause of image artefacts. Artefacts may render images non-diagnostic and measurements unreliable, and most artefacts can only be corrected during the acquisition itself. Hence, timely and accurate recognition of the type of artefact is crucial. This paper provides a concise description of the CMR acquisition process and the underlying MR physics for clinical cardiologists and trainees. Frequently observed CMR artefacts are illustrated and possible adjustments to minimise or eliminate these artefacts are explained. PMID:25339204

van der Graaf, A W M; Bhagirath, P; Ghoerbien, S; Götte, M J W

2014-12-01

45

Essential physics of nuclear acoustic resonance imaging  

NASA Astrophysics Data System (ADS)

Nuclear acoustic resonance (NAR), like nuclear magnetic resonance (NMR), can be used as a spectroscopic imaging tool to detect and characterize soft tissue densities and differences on the atomic scale. Whereas NMR uses electromagnetic radiation to induce energy level transitions, NAR uses acoustic radiation. The frequency of this radiation is typically 1 to 100 MHz; NAR imaging therefore uses ultrasonic energy to induce transitions among the nuclear spin energy levels. By means of piezoelectric transducers, polarized acoustic waves are generated and propagated within a specimen. If these perturbations are in resonance with the specimen's nuclear spin system, then the acoustic waves will periodically modulate an internal magnetic dipole or electric quadrupole interaction as acoustic energy is absorbed. The measurement of this acoustic energy absorption is analogous to the computation of the spin-lattice relaxation time, T1, caused by the release of radiofrequency energy into the surrounding lattice of an excited nucleus and used in magnetic resonance imaging. Accordingly, NAR imaging combines the tools of ultrasound with the techniques of MRI to yield a new and potentially valuable medical imaging modality. The purpose of this paper is to discuss the essential physics of NAR, and to suggest how NAR signals can be processed for medical imaging.

Henderson, Ross M.

1997-05-01

46

Magnetic resonance imaging in dentistry.  

PubMed

MR imaging has found a place in the imaging sciences. These images are unique in that no ionizing radiation is used, the same tissues may or may not have different appearances with different machine settings, a unique set of terms is used to describe the findings in the images, and these findings can be analyzed with the view of obtaining more diagnostic information not readily available with any other imaging modality. Cases have been presented to help demonstrate differences in T1-weighted and T2-weighted sequences as well as the value of contrast material. Additionally, plain film and CT views were included so that they may be contrasted with the MR images. The role and application of CT versus MR imaging has been further discussed and illustrated by Nortjé and van Rensburg. A typical temporomandibular joint case has also been presented. In the future, it is hoped that clinicians will refer more patients for MR imaging so that diagnoses can be made more accurately with analytic software. PMID:10740776

Langlais, R P; van Rensburg, L J; Guidry, J; Moore, W S; Miles, D A; Nortjé, C J

2000-04-01

47

Multidimensionally Encoded Magnetic Resonance Imaging  

E-print Network

algorithm. As an alternative to linear SEMs, nonlinear SEMs have been used to improve the dynamic range-dimensional spatial bases created by linear spa- tial encoding magnetic fields (SEMs). Recently, imaging strat- egies and linear SEMs can be used jointly to further improve the image reconstruction performance. Here, we propose

48

Modern Miracle Medical Machines: Magnetic Resonance Imaging  

NSDL National Science Digital Library

This learning activity teaches the physics of magnetic resonance imaging and NMR. It begins with instruction on the basics of magnetism, electromagnetism, and resonance and applies these topics to the operation of magnetic resonance equipment for medical diagnostics. This activity includes both hands-on exercises and computer visualizations. Information on the construction of the measurement apparatus is available in the instructor resources for the Modern Miracle Medical Machines web site. This one of a growing set of activities developed by the Kansas State University Physics Education Research group on the physics of modern medicine.

Murphy, Sytil K.

2010-06-08

49

Functional magnetic resonance imaging in pediatrics.  

PubMed

Functional magnetic resonance imaging (fMRI) allows non-invasive assessment of human brain function in vivo by detecting blood flow differences. In this review, we want to illustrate the background and different aspects of performing functional magnetic resonance imaging (fMRI) in the pediatric age group. An overview over current and future applications of fMRI will be given, and typical problems, pitfalls, and benefits of doing fMRI in the pediatric age group are discussed. We conclude that fMRI can successfully be applied in children and holds great promise for both research and clinical purposes. PMID:14598227

Wilke, M; Holland, S K; Myseros, J S; Schmithorst, V J; Ball, W S

2003-06-01

50

Image processing for diffusion tensor magnetic resonance imaging  

Microsoft Academic Search

Abstract. This paper, describes image processing techniques for Diffusion Tensor Magnetic Resonance. In Diffusion Tensor MRI, a tensor describing local water diffusion is acquired for each voxel. The geometric nature of the diffusion tensors can quantitatively characterize the local structure in tissues such as bone, muscles, and white matter of the brain. The close relationship between local image structure and

C. F Westin; S. Peled; H. Gubjartsson; R. Kikinis; F. Jolesz

1997-01-01

51

Magnetic Resonance Imaging of the Pediatric Knee.  

PubMed

In pediatric patients, the high resolution and excellent soft-tissue contrast of magnetic resonance (MR) imaging allows for complete evaluation of osseous and soft-tissue structures around the knee joint, and its lack of ionizing radiation makes it a preferred modality for advanced imaging. Older children and adolescents are most commonly imaged to evaluate athletic and traumatic injuries, whereas in infants and school age children MR imaging is used to evaluate developmental conditions such as Blount disease or assess for causes of atraumatic pain such as infection or inflammatory arthritis. A thorough understanding of normal skeletal development is necessary to avoid misdiagnoses. PMID:25442031

Gill, Kara G; Nemeth, Blaise A; Davis, Kirkland W

2014-11-01

52

Review: Magnetic resonance imaging techniques in ophthalmology  

PubMed Central

Imaging the eye with magnetic resonance imaging (MRI) has proved difficult due to the eye’s propensity to move involuntarily over typical imaging timescales, obscuring the fine structure in the eye due to the resulting motion artifacts. However, advances in MRI technology help to mitigate such drawbacks, enabling the acquisition of high spatiotemporal resolution images with a variety of contrast mechanisms. This review aims to classify the MRI techniques used to date in clinical and preclinical ophthalmologic studies, describing the qualitative and quantitative information that may be extracted and how this may inform on ocular pathophysiology. PMID:23112569

Fagan, Andrew J.

2012-01-01

53

Magnetic resonance imaging of the elbow. Part I: Normal anatomy, imaging technique, and osseous abnormalities  

Microsoft Academic Search

Part I of this comprehensive review on magnetic resonance imaging of the elbow discusses normal elbow anatomy and the technical factors involved in obtaining high-quality magnetic resonance images of the elbow. Part I also discusses the role of magnetic resonance imaging in evaluating patients with osseous abnormalities of the elbow. With proper patient positioning and imaging technique, magnetic resonance imaging

Richard Kijowski; Michael Tuite; Matthew Sanford

2004-01-01

54

Cardiovascular magnetic resonance imaging in small animals.  

PubMed

Noninvasive imaging studies involving small animals are becoming increasingly important in preclinical pharmacological, genetic, and biomedical cardiovascular research. Especially small animal magnetic resonance imaging (MRI) using high field and clinical MRI systems has gained significant importance in recent years. Compared to other imaging modalities, like computer tomography, MRI can provide an excellent soft tissue contrast, which enables the characterization of different kinds of tissues without the use of contrast agents. In addition, imaging can be performed with high spatial and temporal resolution. Small animal MRI cannot only provide anatomical information about the beating murine heart; it can also provide functional and molecular information, which makes it a unique imaging modality. Compared to clinical MRI examinations in humans, small animal MRI is associated with additional challenges. These included a smaller size of all cardiovascular structures and a up to ten times higher heart rate. Dedicated small animal monitoring devices make a reliable cardiac triggering and respiratory gating feasible. MRI in combination with molecular probes enables the noninvasive imaging of biological processes at a molecular level. Different kinds of iron oxide or gadolinium-based contrast agents can be used for this purpose. Compared to other molecular imaging modalities, like single photon emission computed tomography (SPECT) and positron emission tomography (PET), MRI can also provide imaging with high spatial resolution, which is of high importance for the assessment of the cardiovascular system. The sensitivity for detection of MRI contrast agents is however lower compared to sensitivity of radiation associated techniques like PET and SPECT. This chapter is divided into the following sections: (1) "Introduction," (2) "Principals of Magnetic Resonance Imaging," (3) "MRI Systems for Preclinical Imaging and Experimental Setup," and (4) "Cardiovascular Magnetic Resonance Imaging." PMID:22137434

Botnar, René M; Makowski, Marcus R

2012-01-01

55

Neurosurgical uses for intraprocedural magnetic resonance imaging.  

PubMed

Neurosurgical procedures demand precision, and efforts to create accurate neurosurgical navigation have been central to the profession through its history. Magnetic resonance image (MRI)-guided navigation offers the possibility of real-time, image-based stereotactic information for the neurosurgeon, which makes possible a number of diagnostic and therapeutic procedures. This article will review both current options for intraoperative MRI operative suite arrangements and the current therapeutic/diagnostic uses of intraoperative MRI. PMID:16924171

Mutchnick, Ian S; Moriarty, Thomas M

2005-10-01

56

Magnetic resonance images of chronic patellar tendinitis  

Microsoft Academic Search

Chronic patellar tendinitis can be a frustrating diagnostic and therapeutic problem. This report evaluates seven tendons in five patients with chronic patellar tendinitis. The etiologies included “jumper's knee” and Osgood-Schlatter disease. In all cases magnetic resonance images (MRI) showed thickening of the tendon. Some of the tendons had focal areas of thickening which helped establish the etiology. All cases had

David Bodne; Stephen F. Quinn; William T. Murray; Thomas Bolton; Steven Rudd; Kirk Lewis; Peter Daines; John Bishop; Courtney Cochran

1988-01-01

57

Magnetic Resonance Imaging in Endodontic Treatment Prediction  

Microsoft Academic Search

The necessary condition for successful endodontic treatment is the precise mapping of the shape of dental cavities. The aim of this work has been an elaboration and verification of the possibility of using three-dimensional (3D) spin echo magnetic resonance imaging (MRI) techniques in dentistry. Six extracted molar teeth were used for measurements without additional preparation and after endodontic preparation. MRI

Marta Tanasiewicz

2010-01-01

58

HOSPITAL PHYSICS: Magnetic resonance imaging and spectroscopy  

Microsoft Academic Search

Nuclear Magnetic Resonance (NMR) was first described in the scientific literature 50 years ago when Bloch and Purcell, working independently, showed how certain nuclei placed in a magnetic field absorbed energy in the radiofrequency range and re-emitted this energy during their transition back to the relaxed state (Bloch 1946, Purcell 1946). This phenomenon has since revolutionized medical imaging with its

Caroline Andrews; Andrew Simmons; Steve Williams

1996-01-01

59

Functional Magnetic Resonance Imaging of Pain Consciousness  

E-print Network

reflex sympathetic dystrophy (RSD) and chronic back pain. The review emphasizes that differentFunctional Magnetic Resonance Imaging of Pain Consciousness: Cortical Networks of Pain Critically Depend on What is Implied by "Pain" A. Vania Apkarian, PhD Address SUNY Health Science Center, Department

Apkarian, A. Vania

60

Magnetic resonance imaging of the postoperative spine.  

PubMed

Magnetic resonance (MR) imaging is an excellent technique for evaluating the postoperative spine when the patient has chronic or recurrent symptoms. Potential causes of pain following lumbar surgery include arachnoiditis, stenosis, epidural fibrosis and disc herniations, pseudomeningocele, and infection. The postoperative cervical spine may be complicated by hematoma, canal or foraminal stenosis, disc herniation, and cord abnormality. This article reviews standard imaging protocols, the normal postoperative appearance of the spine, and the characteristic imaging findings for each of the abnormal postoperative conditions. PMID:11371319

Ross, J S

2000-01-01

61

Magnetic Resonance Imaging of Cartilage Repair Procedures.  

PubMed

Cartilage injuries in the knee are common and can be a persistent source of pain or dysfunction. Many new surgical strategies have been developed to treat these lesions. It is important for the radiologist to have an understanding of these procedures and their appearance on magnetic resonance (MR) imaging. This article provides the radiologist with an overview of the surgical strategies for repairing cartilage lesions in the knee followed by a discussion of their postoperative appearance on MR imaging in normal and abnormal cases. Guidelines for adequate reporting of the MR imaging findings after cartilage repair in the knee are also included. PMID:25442028

Forney, Michael C; Gupta, Amit; Minas, Tom; Winalski, Carl S

2014-11-01

62

Contrast testing for magnetic resonance imaging.  

PubMed

A test phantom for evaluating magnetic resonance image contrast was constructed using separate chambers filled with manganese chloride (MnCl2) solutions of different concentrations. The concentrations were chosen so that the relaxation times produced were distributed over the range appropriate for human tissues in brain imaging. Specific solutions had relaxation properties similar to those of white matter, gray matter, and brain tumors. The region surrounding the chambers was filled with a sodium chloride solution with conductivity similar to that of brain tissue so that radiofrequency signal absorption would be appropriate. When magnetic resonance relaxation response curves were obtained with the phantom, relaxation contrast and latitude could be compared for different imaging pulse sequences. Contrast responses for gradient echo sequences differed considerably when the flip angle was changed. PMID:2720266

Anderson, D W; Yamanashi, W S; Stanley, D W; Wohler, J B

1989-01-01

63

Functional magnetic resonance imaging (FMRI) of the human brain  

Microsoft Academic Search

Functional magnetic resonance imaging (FMRI) can provide detailed images of human brain that reflect localized changes in cerebral blood flow and oxygenation induced by sensory, motor, or cognitive tasks. This review presents methods for gradient-recalled echo-planar functional magnetic resonance imaging (FMRI). Also included is a discussion of the hypothesized basis of FMRI, imaging hardware, a unique visual stimulation apparatus, image

Edgar A. DeYoe; Peter Bandettini; Jay Neitz; David Miller; Paula Winans

1994-01-01

64

3D-Computerized facial reconstructions from 3D-MRI of human heads using deformable model approach  

Microsoft Academic Search

The aim of facial reconstruction is to estimate the face of an unknown individual from the shape of his\\/her skull to aid in recognition and identification. In this paper a 3D computerized facial reconstruction method from 3D-MRI of human heads is presented. It based on a model deformable approach constrained by the knowledge of soft tissues thicknesses, at a certain

Adel Kermi; S. Marniche-Kermi; M. T. Laskri

2010-01-01

65

Magnetic resonance imaging of osteonecrosis.  

PubMed

Because the available preliminary data strongly indicate that MRI is accurate in diagnosing osteonecrosis, MRI of the hips is recommended in patients suspected of having osteonecrosis, especially if other diagnostic studies are equivocal. MRI also may be useful in following patients who have strong risk factors for osteonecrosis, such as corticosteroid therapy, femoral neck fracture, traumatic femoral head dislocation (Fig. 13), slipped capital femoral epiphysis (Fig. 14), and congenital hip dislocation. In diseases such as systemic lupus erythematosus, both hips eventually may become involved in 50 to 80 per cent of cases. Therefore, the unaffected hip of patients with systemic lupus erythematosus and unilateral nontraumatic osteonecrosis of the hip should be monitored regularly with MRI. The hope is that early diagnosis and treatment of femoral head osteonecrosis will prevent the relentless progression to subchondral collapse and disabling arthropathy. MRI also may be useful in staging patients known to have osteonecrosis. The ability of MRI to image directly in multiple planes facilitates the determination of the volume and location of infarcted segments of bone. This information is important in planning any of the surgical procedures used relatively early in the disease, such as core decompression, rotational osteotomy, or bone graft. Moreover, MRI may prove helpful in evaluating the effectiveness of any therapeutic intervention. PMID:3714996

Gillespy, T; Genant, H K; Helms, C A

1986-06-01

66

Image Processing for Diffusion Tensor Magnetic Resonance Imaging  

Microsoft Academic Search

This paper1 describes image processing techniques for Diffusion Ten- sor Magnetic Resonance. In Diffusion Tensor MRI, a tensor describing local wa- ter diffusion is acquired for each voxel. The geometric nature of the diffusion tensors can quantitatively characterize the local structure in tissues such as bone, muscles, and white matter of the brain. The close relationship between local im- age

Carl-fredrik Westin; S. E. Maier; B. Khidhir; Peter Everett; Ferenc A. Jolesz; Ron Kikinis

1999-01-01

67

Magnetic resonance imaging of renal transplants  

SciTech Connect

Nineteen patients were examined to determine the clinical potential of magnetic resonance imaging (MRI) for evaluation of renal transplants. Of the six living-related transplants with good renal function that were imaged, five demonstrated good corticomedullary differentiation (CMD) and one faint CMD. Three transplants with acute rejection were imaged, and all demonstrated a decrease in CMD and decrease in overall signal intensity compared with baseline. No CMD was seen in the three chronically rejecting transplants imaged. The appearance of cadaveric transplants and acute tubular necrosis was quite variable. All perinephric fluid collections were well depicted by MRI. Lymphoceles could be distinguished from hematomas. MRI may prove to be a useful adjunct in the evaluation of renal transplant and perinephric fluid collections.

Geisinger, M.A.; Risius, B.; Jordan, M.L.; Zelch, M.G.; Novick, A.C.; George, C.R.

1984-12-01

68

Magnetic resonance imaging of pancreatitis: an update.  

PubMed

Magnetic resonance (MR) imaging plays an important role in the diagnosis and staging of acute and chronic pancreatitis and may represent the best imaging technique in the setting of pancreatitis due to its unmatched soft tissue contrast resolution as well as non-ionizing nature and higher safety profile of intravascular contrast media, making it particularly valuable in radiosensitive populations such as pregnant patients, and patients with recurrent pancreatitis requiring multiple follow-up examinations. Additional advantages include the ability to detect early forms of chronic pancreatitis and to better differentiate adenocarcinoma from focal chronic pancreatitis. This review addresses new trends in clinical pancreatic MR imaging emphasizing its role in imaging all types of acute and chronic pancreatitis, pancreatitis complications and other important differential diagnoses that mimic pancreatitis. PMID:25356038

Manikkavasakar, Sriluxayini; AlObaidy, Mamdoh; Busireddy, Kiran K; Ramalho, Miguel; Nilmini, Viragi; Alagiyawanna, Madhavi; Semelka, Richard C

2014-10-28

69

Metabolite specific proton magnetic resonance imaging.  

PubMed Central

An imaging method is described that makes use of proton double quantum nuclear magnetic resonance (NMR) to construct images based on selected metabolites such as lactic acid. The optimization of the method is illustrated in vitro, followed by in vivo determination of lactic acid distribution in a solid tumor model. Water suppression and editing of lipid signals are such that two-dimensional spectra of lactic acid may be obtained from a radiation-induced fibrosarcoma (RIF-1) tumor in under 1 min and lactic acid images from the same tumor in under 1 hr at 2.0 T. This technique provides a fast and reproducible method at moderate magnetic field strength for mapping biologically relevant metabolites. Images PMID:2734292

Hurd, R E; Freeman, D M

1989-01-01

70

In vivo nuclear magnetic resonance imaging  

NASA Technical Reports Server (NTRS)

During the past year the Woodlands Baylor Magnetic Resonance Imaging (MRI) facility became fully operational. A detailed description of this facility is given. One significant instrument addition this year was the 100 MHz, 40cm bore superconducting imaging spectrometer. This instrument gives researchers the capability to acquire high energy phosphate spectra. This will be used to investigate ATP, phosphocreatinine and inorganic phosphate changes in normal and atrophied muscle before, during and after exercise. An exercise device for use within the bore of the imaging magnet is under design/construction. The results of a study of T sub 1 and T sub 2 changes in atrophied muscle in animals and human subjects are given. The imaging and analysis of the lower leg of 15 research subjects before and after 5 weeks of complete bedrest was completed. A compilation of these results are attached.

Leblanc, A.

1986-01-01

71

Magnetic resonance imaging of perianal fistulas.  

PubMed

Perianal fistulization is the result of a chronic inflammation of the perianal tissues. A wide spectrum of clinical manifestations, ranging from simple to complex fistulas, can be seen, the latter especially in patients with Crohn disease. Failure to detect secondary tracks and hidden abscesses may lead to therapeutic failure, such as insufficient response to medical treatment and relapse after surgery. Currently, magnetic resonance (MR) imaging is the preferred technique for evaluating perianal fistulas and associated complications. Initially used most often in the preoperative setting, MR imaging now also plays an important role in evaluating the response to medical therapy. PMID:24238135

Vanbeckevoort, Dirk; Bielen, Didier; Vanslembrouck, Ragna; Van Assche, Gert

2014-02-01

72

Multiparametric magnetic resonance imaging of prostate cancer.  

PubMed

In India, prostate cancer has an incidence rate of 3.9 per 100,000 men and is responsible for 9% of cancer-related mortality. It is the only malignancy that is diagnosed with an apparently blind technique, i.e., transrectal sextant biopsy. With increasing numbers of high-Tesla magnetic resonance imaging (MRI) equipment being installed in India, the radiologist needs to be cognizant about endorectal MRI and multiparametric imaging for prostate cancer. In this review article, we aim to highlight the utility of multiparamteric MRI in prostate cancer. It plays a crucial role, mainly in initial staging, restaging, and post-treatment follow-up. PMID:23599562

Hedgire, Sandeep S; Oei, Tamara N; McDermott, Shaunagh; Cao, Kai; Patel M, Zena; Harisinghani, Mukesh G

2012-07-01

73

Magnetic resonance imaging of small bowel neoplasms  

PubMed Central

Abstract Magnetic resonance (MR) imaging is rapidly increasing clinical acceptance to evaluate the small bowel and can be the initial imaging method to investigate small bowel diseases. MR examinations may provide the first opportunity to detect and characterize tumours of the small bowel. Intra- and extraluminal MR findings, combined with contrast enhancement and functional information, help to make an accurate diagnosis and consequently characterize small bowel neoplasms. MR enteroclysis should be recommended for the initial investigation in patients suspected of having small bowel tumours. In this article, the MR findings of primary small bowel neoplasms are described and the MR findings for the differential diagnosis are discussed. PMID:23524074

Casciani, Emanuele; Polettini, Elisabetta; Laghi, Francesca; Gualdi, Gianfranco

2013-01-01

74

Multiparametric magnetic resonance imaging of prostate cancer  

PubMed Central

In India, prostate cancer has an incidence rate of 3.9 per 100,000 men and is responsible for 9% of cancer-related mortality. It is the only malignancy that is diagnosed with an apparently blind technique, i.e., transrectal sextant biopsy. With increasing numbers of high-Tesla magnetic resonance imaging (MRI) equipment being installed in India, the radiologist needs to be cognizant about endorectal MRI and multiparametric imaging for prostate cancer. In this review article, we aim to highlight the utility of multiparamteric MRI in prostate cancer. It plays a crucial role, mainly in initial staging, restaging, and post-treatment follow-up. PMID:23599562

Hedgire, Sandeep S; Oei, Tamara N; Mcdermott, Shaunagh; Cao, Kai; Patel M, Zena; Harisinghani, Mukesh G

2012-01-01

75

Magnetic resonance imaging of fibrosing mediastinitis  

SciTech Connect

Magnetic resonance imaging (MRI) was performed in seven patients with fibrosing mediastinitis. Comparison was made in each case to standard chest radiography and computed tomography (CT). Angiography was performed in three cases. Although MRI and CT were found to be equivalent in defining the extent of adenopathy, CT was superior at demonstrating calcifications, often important in making the diagnosis of fibrosing mediastinitis. MRI, however, offered complementary information, particularly in assessing vascular patency without the need for intravenous contrast media. On T2-weighted images, the adenopathy associated with fibrosing mediastinitis was noted to be of relatively low signal intensity, possibly indicating its benign nature.

Rholl, K.S.; Levitt, R.G.; Glazer, H.S.

1985-08-01

76

Diagnostic Magnetic Resonance Imaging of the Breast  

PubMed Central

Contrast enhanced breast magnetic resonance imaging is a modality that is frequently used into the breast radiologist’s daily clinical practice. MRI examination should have optimal technical proficiency in order to attain diagnostic quality avoiding false positive and negative diagnoses. Furthermore, due to increasing usage fields of the examinations uniting with high sensitivity phenomenon, excessive usage and excision/interventional procedures are inevitable. Therefore, we hope to highlight the appropriate usage of the MRI technique and it’s clinical applications.

Kilic, Fahrettin; Ogul, Hayri; Bayraktutan, Ummugulsum; Gumus, Hatice; Unal, Ozlem; Kantarci, Mecit; Yilmaz, M. Halit

2012-01-01

77

Musculoskeletal magnetic resonance imaging: importance of radiography  

Microsoft Academic Search

ObjectiveTo determine the usefulness of radiography for interpretation of musculoskeletal (MSK) magnetic resonance imaging (MRI) studies.Designs and patientsIn a 1-year period, 1,030 MSK MRI studies were performed in 1,002 patients in our institution. For each study, the interpreting radiologist completed a questionnaire regarding the availability and utility of radiographs, radiological reports and clinical information for the interpretation of the MRI

Mihra S. Taljanovic; Tim B. Hunter; Kimberly A. Fitzpatrick; Elizabeth A. Krupinski; Thomas L. Pope

2003-01-01

78

Magnetic Resonance Imaging of Hepatocellular Carcinoma  

Microsoft Academic Search

In hepatocellular carcinomas (HCCs), T1 shortening occurs due to internal protein, fat, copper, iron, hypercellularity, or a combination thereof. T1-weighted magnetic resonance imaging (MRI) is obtained with a non-fat-suppressed phase shift [in- (4 ms) and opposed- (2 ms) phase] gradient-echo sequence. Internal fat deposition is often (36%) seen in well-differentiated HCCs between 1.1 and 1.5 cm in size. T2-weighted MRI

Masayuki Kanematsu; Hiroshi Kondo; Satoshi Goshima; Yusuke Tsuge; Haruo Watanabe

2008-01-01

79

Magnetic resonance imaging. Application to family practice.  

PubMed Central

OBJECTIVE: To review indications, contraindications, and risks of using magnetic resonance imaging (MRI) in order to help primary care physicians refer patients appropriately for MRI, screen for contraindications to using MRI, and educate patients about MRI. QUALITY OF EVIDENCE: Recommendations are based on classic textbooks, the policies of our MRI group, and a literature search using MEDLINE with the MeSH headings magnetic resonance imaging, brain, musculoskeletal, and spine. The search was limited to human, English-language, and review articles. Evidence in favour of using MRI for imaging the head, spine, and joints is well established. For cardiac, abdominal, and pelvic conditions, MRI has been shown useful for certain indications, usually to complement other modalities. MAIN MESSAGE: For demonstrating soft tissue conditions, MRI is better than computed tomography (CT), but CT shows bone and acute bleeding better. Therefore, patients with trauma or suspected intracranial bleeding should have CT. Tumours, congenital abnormalities, vascular structures, and the cervical or thoracic spine show better on MRI. Either modality can be used for lower back pain. Cardiac, abdominal, and pelvic abnormalities should be imaged with ultrasound or CT before MRI. Contraindications for MRI are mainly metallic implants or shrapnel, severe claustrophobia, or obesity. CONCLUSIONS: With the increasing availability of MRI scanners in Canada, better understanding of the indications, contraindications, and risks will be helpful for family physicians and their patients. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 PMID:10509224

Goh, R. H.; Somers, S.; Jurriaans, E.; Yu, J.

1999-01-01

80

Magnetic resonance imaging: present and future applications  

PubMed Central

Magnetic resonance (MR) imaging has created considerable excitement in the medical community, largely because of its great potential to diagnose and characterize many different disease processes. However, it is becoming increasingly evident that, because MR imaging is similar to computed tomography (CT) scanning in identifying structural disorders and because it is more costly and difficult to use, this highly useful technique must be judged against CT before it can become an accepted investigative tool. At present MR imaging has demonstrated diagnostic superiority over CT in a limited number of important, mostly neurologic, disorders and is complementary to CT in the diagnosis of certain other disorders. For most of the remaining organ systems its usefulness is not clear, but the lack of ionizing radiation and MR's ability to produce images in any tomographic plane may eventually prove to be advantageous. The potential of MR imaging to display in-vivo spectra, multinuclear images and blood-flow data makes it an exciting investigative technique. At present, however, MR imaging units should be installed only in medical centres equipped with the clinical and basic research facilities that are essential to evaluate the ultimate role of this technique in the care of patients. ImagesFig. 5Fig. 6Fig. 7Fig. 8Fig. 9Fig. 10Fig. 11Fig. 12Fig. 13Fig. 14 PMID:3884120

Johnston, Donald L.; Liu, Peter; Wismer, Gary L.; Rosen, Bruce R.; Stark, David D.; New, Paul F.J.; Okada, Robert D.; Brady, Thomas J.

1985-01-01

81

Gastrointestinal imaging-practical magnetic resonance imaging approach.  

PubMed

Over the past two decades, advances in cross-sectional imaging such as computed tomography and magnetic resonance imaging (MRI) have dramatically changed the concept of gastrointestinal imaging. MR is playing an increasing role in the evaluation of gastrointestinal disorders. MRI combines the advantages of excellent soft-tissue contrast, noninvasiveness, functional information and lack of ionizing radiation. Furthermore, recent developments of MRI have led to improved spatial and temporal resolution as well as decreased motion artifacts. In this article we describe the technical aspects of gastrointestinal MRI and present a practical approach for a well-known spectrum of gastrointestinal disease processes. PMID:25170393

Liu, Baodong; Ramalho, Miguel; AlObaidy, Mamdoh; Busireddy, Kiran K; Altun, Ersan; Kalubowila, Janaka; Semelka, Richard C

2014-08-28

82

Graph theory based algorithm for magnetic resonance brain images segmentation  

Microsoft Academic Search

Image segmentation is often required as a preliminary and indispensable stage in the computer aided medical image process, particularly during the clinical analysis of magnetic resonance (MR) brain images. The segmentation of magnetic resonance image (MRI) is a challenging problem that has received an enormous amount of attention lately. In this paper, we propose a simple and effective segmentation method

Jianzhong Wang; Di Liu; Lili Dou; Baoxue Zhang; Jun Kong; Yinghua Lu

2008-01-01

83

Quantitative Pulmonary Imaging Using Computed Tomography and Magnetic Resonance Imaging  

PubMed Central

Measurements of lung function, including spirometry and body plethesmography, are easy to perform and are the current clinical standard for assessing disease severity. However, these lung functional techniques do not adequately explain the observed variability in clinical manifestations of disease and offer little insight into the relationship of lung structure and function. Lung imaging and the image based assessment of lung disease has matured to the extent that it is common for clinical, epidemiologic, and genetic investigation to have a component dedicated to image analysis. There are several exciting imaging modalities currently being used for the non-invasive study of lung anatomy and function. In this review we will focus on two of them, x-ray computed tomography and magnetic resonance imaging. Following a brief introduction of each method we detail some of the most recent work being done to characterize smoking-related lung disease and the clinical applications of such knowledge. PMID:22142490

Washko, George R.; Parraga, Grace; Coxson, Harvey O.

2011-01-01

84

Model-based reconstruction of magnetic resonance spectroscopic imaging  

E-print Network

Magnetic resonance imaging (MRI) is a medical imaging technique that is used to obtain images of soft tissue throughout the body. Since its development in the 1970s, MRI has gained tremendous importance in clinical practice ...

Chatnuntawech, Itthi

2013-01-01

85

The magnetic resonance imaging-linac system.  

PubMed

The current image-guided radiotherapy systems are suboptimal in the esophagus, pancreas, kidney, rectum, lymph node, etc. These locations in the body are not easily accessible for fiducials and cannot be visualized sufficiently on cone-beam computed tomographies, making daily patient set-up prone to geometrical uncertainties and hinder dose optimization. Additional interfraction and intrafraction uncertainties for those locations arise from motion with breathing and organ filling. To allow real-time imaging of all patient tumor locations at the actual treatment position a fully integrated 1.5-T, diagnostic quality, magnetic resonance imaging with a 6-MV linear accelerator is presented. This system must enable detailed dose painting at all body locations. PMID:24931095

Lagendijk, Jan J W; Raaymakers, Bas W; van Vulpen, Marco

2014-07-01

86

Magnetic resonance imaging at ultrahigh fields.  

PubMed

Since the introduction of 4 T human systems in three academic laboratories circa 1990, rapid progress in imaging and spectroscopy studies in humans at 4 T and animal model systems at 9.4 T have led to the introduction of 7 T and higher magnetic fields for human investigation at about the turn of the century. Work conducted on these platforms has demonstrated the existence of significant advantages in SNR and biological information content at these ultrahigh fields, as well as the presence of numerous challenges. Primary difference from lower fields is the deviation from the near field regime; at the frequencies corresponding to hydrogen resonance conditions at ultrahigh fields, the RF is characterized by attenuated traveling waves in the human body, which leads to image nonuniformities for a given sample-coil configuration because of interferences. These nonuniformities were considered detrimental to the progress of imaging at high field strengths. However, they are advantageous for parallel imaging for signal reception and parallel transmission, two critical technologies that account, to a large extend, for the success of ultrahigh fields. With these technologies, and improvements in instrumentation and imaging methods, ultrahigh fields have provided unprecedented gains in imaging of brain function and anatomy, and started to make inroads into investigation of the human torso and extremities. As extensive as they are, these gains still constitute a prelude to what is to come given the increasingly larger effort committed to ultrahigh field research and development of ever better instrumentation and techniques. PMID:24686229

Ugurbil, Kamil

2014-05-01

87

Advancing magnetic resonance imaging in Crohn's disease.  

PubMed

Crohn's disease (CD) is a lifelong chronic inflammatory bowel disease associated with diarrhea, abdominal pain, bloody stool and often perianal fistulae. Inflammation in CD involves the entire gastrointestinal tract, especially including the small and large bowels, causing irreversible bowel damage. Frequent imaging examinations are necessary to monitor disease activity and to evaluate response to therapeutic interventions, and, furthermore, to predict recurrence in order to provide appropriate treatment. The suitable imaging modality should be reproducible, well tolerated, safe and free of ionizing radiation. In recent years, imaging used in CD has dramatically changed. Cross-sectional imaging techniques such as computed tomography and magnetic resonance imaging (MRI) are used to investigate not only extraluminal abnormalities, but also intraluminal changes. Recently, new techniques such as MR enteroclysis, enterography, colonography and enterocolonography have been developed. These recent advances enable the use of MRI to assess bowel disorders with high sensitivity, specificity and accuracy. MRI can evaluate simultaneously the bowel surface, bowel wall, abdominal abscesses and perianal lesions, such as perianal fistulae and perianal abscesses, without the problem of overlapping bowel loops. Therefore, MRI has the potential for evaluation of the overall disease activity of CD without radiation exposure. We believe that MRI is a suitable first choice imaging modality in the assessment of CD. PMID:24458109

Fujii, Toshimitsu; Naganuma, Makoto; Kitazume, Yoshio; Saito, Eiko; Nagahori, Masakazu; Ohtsuka, Kazuo; Watanabe, Mamoru

2014-01-01

88

Magnetic resonance imaging of prosthetic heart valves.  

PubMed

To evaluate the safety of magnetic resonance (MR) imaging of prosthetic heart valves, nine different synthetic and tissue valves were studied ex vivo. Deflection was measured in 0.35-tesla (T) and 1.5-T superconducting magnets and at the edge of the bore of a 2.35-T electromagnet in field gradients of 5, 1.1, and 6.3 mT/cm, respectively. No valve deflected in the 0.35-T magnet; six synthetic valves deflected 0.25 degrees-3 degrees in the 1.5-T magnet; all valves deflected 1 degree-27 degrees at the edge of the 2.35-T magnet. Each valve was then submerged in a vial of water and the temperature was measured immediately before and after each of two spin-echo imaging sequences in the two superconducting magnets. No significant temperature rise followed exposure in either magnet. Image distortion varied from negligible to severe in both imagers; magnitude of distortion paralleled magnitude of deflection. These data suggest that patients with present-day prosthetic heart valves can be safely imaged in present-day MR imagers and that prosthesis-induced artifacts will not interfere with interpretation in most instances. PMID:3969474

Soulen, R L; Budinger, T F; Higgins, C B

1985-03-01

89

Ferromagnetic resonance imaging of Co films using magnetic resonance force microscopy  

E-print Network

Ferromagnetic resonance imaging of Co films using magnetic resonance force microscopy B. J. Suh, P is similar to that used in magnetic force microscopy MFM ,4 where only the spin magnetization in the vicinity of microscopic ferromagnetic resonance FMR detected using the magnetic resonance force microscope MRFM

Hammel, P. Chris

90

Tools for cardiovascular magnetic resonance imaging  

PubMed Central

In less than fifteen years, as a non-invasive imaging option, cardiovascular MR has grown from a being a mere curiosity to becoming a widely used clinical tool for evaluating cardiovascular disease. Cardiovascular magnetic resonance imaging (CMRI) is now routinely used to study myocardial structure, cardiac function, macro vascular blood flow, myocardial perfusion, and myocardial viability. For someone entering the field of cardiac MR, this rapid pace of development in the field of CMRI might make it difficult to identify a cohesive starting point. In this brief review, we have attempted to summarize the key cardiovascular imaging techniques that have found widespread clinical acceptance. In particular, we describe the essential cardiac and respiratory gating techniques that form the backbone of all cardiovascular imaging methods. It is followed by four sections that discuss: (I) the gradient echo techniques that are used to assess ventricular function; (II) black-blood turbo spin echo (SE) methods used for morphologic assessment of the heart; (III) phase-contrast based techniques for the assessment of blood flow; and (IV) CMR methods for the assessment of myocardial ischemia and viability. In each section, we briefly summarize technical considerations relevant to the clinical use of these techniques, followed by practical information for its clinical implementation. In each of those four areas, CMRI is considered either as the benchmark imaging modality against which the diagnostic performance of other imaging modalities are compared against, or provides a complementary capability to existing imaging techniques. We have deliberately avoided including cutting-edge CMR imaging techniques practiced at few academic centers, and restricted our discussion to methods that are widely used and are likely to be available in a clinical setting. Our hope is that this review would propel an interested reader toward more comprehensive reviews in the literature. PMID:24834409

Krishnamurthy, Ramkumar; Cheong, Benjamin

2014-01-01

91

Pleural endometriosis: findings on magnetic resonance imaging.  

PubMed

Endometriosis is a benign gynecological disorder associated with pelvic pain and infertility, primarily affecting women of reproductive age. Thoracic endometriosis affects the pulmonary parenchyma or pleura. We report the cases of two patients with pleural endometriosis who presented with recurrent pneumothorax. In both cases, magnetic resonance imaging (MRI) of the chest showed right hydropneumothorax and well-defined, rounded nodules on the pleural surface in the right hemithorax. We conclude that MRI is a good option for the characterization of pleural endometriotic nodules and hemorrhagic pleural effusion. PMID:23288127

Marchiori, Edson; Zanetti, Gláucia; Rodrigues, Rosana Souza; Souza, Luciana Soares; Souza Junior, Arthur Soares; Francisco, Flávia Angélica Ferreira; Hochhegger, Bruno

2012-01-01

92

Foundations of Advanced Magnetic Resonance Imaging  

PubMed Central

Summary: During the past decade, major breakthroughs in magnetic resonance imaging (MRI) quality were made by means of quantum leaps in scanner hardware and pulse sequences. Some advanced MRI techniques have truly revolutionized the detection of disease states and MRI can now—within a few minutes—acquire important quantitative information noninvasively from an individual in any plane or volume at comparatively high resolution. This article provides an overview of the most common advanced MRI methods including diffusion MRI, perfusion MRI, functional MRI, and the strengths and weaknesses of MRI at high magnetic field strengths. PMID:15897944

Bammer, Roland; Skare, Stefan; Newbould, Rexford; Liu, Chunlei; Thijs, Vincent; Ropele, Stefan; Clayton, David B.; Krueger, Gunnar; Moseley, Michael E.; Glover, Gary H.

2005-01-01

93

Creating a magnetic resonance imaging ontology.  

PubMed

The goal of this work is to build an ontology of Magnetic Resonance Imaging. The MRI domain has been analysed regarding MRI simulators and the DICOM standard. Tow MRI simulators have been analysed: JEMRIS, which is developed in XML and C++, has a hierarchical organisation and SIMRI, which is developed in C, has a good representation of MRI physical processes. To build the ontology we have used Protégé 4, owl2 that allows quantitative representations. The ontology has been validated by a reasoner (Fact++) and by a good representation of DICOM headers and of MRI processes. The MRI ontology would improved MRI simulators and eased semantic interoperability. PMID:21893854

Lasbleiz, Jérémy; Saint-Jalmes, Hervé; Duvauferrier, Régis; Burgun, Anita

2011-01-01

94

Creating a magnetic resonance imaging ontology  

PubMed Central

The goal of this work is to build an ontology of Magnetic Resonance Imaging. The MRI domain has been analysed regarding MRI simulators and the DICOM standard. Tow MRI simulators have been analysed: JEMRIS, which is developed in XML and C++, has a hierarchical organisation and SIMRI, which is developed in C, has a good representation of MRI physical processes. To build the ontology we have used Protégé 4, owl2 that allows quantitative representations. The ontology has been validated by a reasoner (Fact++) and by a good representation of DICOM headers and of MRI processes. The MRI ontology would improved MRI simulators and eased semantic interoperability. PMID:21893854

Lasbleiz, Jérémy; Saint-Jalmes, Hervé; Duvauferrier, Régis; Burgun, Anita

2011-01-01

95

Designing Magnetic Resonance Imaging Curriculum for Undergraduates  

NSDL National Science Digital Library

A new hands-on curriculum developed at Vanderbilt University focuses on teaching medical imaging, specifically magnetic resonance imaging(MRI). This material was designed to engage students in real world applications of biomedical engineering through challenge based activities. These activities include homework, quizzes, and hands-on experiments. The materials for each activity are easy to find and can be purchased for under $25. The curriculum begins with a Grand Challenge that presents a medical case in order to interest the students. The challenge questions allow the students to play the role of the patient, technician, and physician. The material was organized in five modules: Electromagnetic Fields and Magnetic Moments, Spin Behavior: Excitation and Relaxation, Spatial Encoding and Detecting Signals, Image Reconstruction, and Image Characteristics. In addition, there are expert interviews that provide the students with multiple perspectives on the information. The material was tested in the summer of 2007 on five students in order to gain feedback, correct errors, and gauge student understanding. Testing showed that the curriculum had a positive impact on student interest in biomedical imaging and resulted in several improvements and additions to the curriculum. During the academic year, the materials will be field-tested at the undergraduate and high school level. Additionally, the materials are being adapted for high school level implementation.

96

Fast noniterative registration of magnetic resonance images  

NASA Astrophysics Data System (ADS)

EvIdent (EVent IDENTification) is an exploratory data analysis system for the detection and investigation of novelty, identified for a region of interest and its characteristics, within a set of images. For functional magnetic resonance imaging, for instance, a characteristic of the region of interest is a time course, which represents the intensity value of voxels over several discrete instances in time. An essential preprocessing step is the rapid registration of these images prior to analysis. Two dimensional image registration coefficients are obtained within EvIdent by solving a regression problem based on integration of a linearized matching equation over a set of patches in the image space. The registration method is robust to noise, offers a flexible hierarchical procedure, is easily generalizable to 3D registration, and is well suited to parallel processing. EvIdent, written in Java and C++, offers a sophisticated data model, an extensible algorithm framework, and a suite of graphical user interface constructs. We describe the registration algorithm and its implementation within the EvIdent software.

Pizzi, Nicolino J.; Alexander, Murray; Vivanco, Rodrigo A.; Somorjai, Raymond L.

2001-07-01

97

Cardiac imaging using gated magnetic resonance  

SciTech Connect

To overcome the limitations of magnetic resonance (MR) cardiac imaging using nongated data acquisition, three methods for acquiring a gating signal, which could be applied in the presence of a magnetic field, were tested; an air-filled plethysmograph, a laser-Doppler capillary perfusion flowmeter, and an electrocardiographic gating device. The gating signal was used for timing of MR imaging sequences (IS). Application of each gating method yielded significant improvements in structural MR image resolution of the beating heart, although with both plethysmography and laser-Doppler velocimetry it was difficult to obtain cardiac images from the early portion of the cardiac cycle due to an intrinsic delay between the ECG R wave and peripheral detection of the gating signal. Variations in the temporal relationship between the R wave and plethysmographic and laser-Doppler signals produced inconsistencies in the timing of IS. Since the ECG signal is virtually free of these problems, the preferable gating technique is IS synchronization with an electrocardiogram. The gated images acquired with this method provide sharp definition of internal cardiac morphology and can be temporarily referenced to end diastole and end systole or intermediate points.

Lanzer, P.; Botvinick, E.H.; Schiller, N.B.

1984-01-01

98

MAGNETIC RESONANCE IMAGE SYNTHESIS THROUGH PATCH REGRESSION.  

PubMed

Magnetic resonance imaging (MRI) is widely used for analyzing human brain structure and function. MRI is extremely versatile and can produce different tissue contrasts as required by the study design. For reasons such as patient comfort, cost, and improving technology, certain tissue contrasts for a cohort analysis may not have been acquired during the imaging session. This missing pulse sequence hampers consistent neuroanatomy research. One possible solution is to synthesize the missing sequence. This paper proposes a data-driven approach to image synthesis, which provides equal, if not superior synthesis compared to the state-of-the-art, in addition to being an order of magnitude faster. The synthesis transformation is done on image patches by a trained bagged ensemble of regression trees. Validation was done by synthesizing T 2-weighted contrasts from T 1-weighted scans, for phantoms and real data. We also synthesized 3 Tesla T 1-weighted magnetization prepared rapid gradient echo (MPRAGE) images from 1.5 Tesla MPRAGEs to demonstrate the generality of this approach. PMID:24443686

Jog, Amod; Roy, Snehashis; Carass, Aaron; Prince, Jerry L

2013-12-31

99

[Magnetic resonance imaging in multiple sclerosis].  

PubMed

The contribution of magnetic resonance imaging techniques to the clinical prognosis of multiple sclerosis. Magnetic resonance imaging (MRI) is a diagnostic technique with a high sensitivity for the detection of lesions, but with a poor pathological specificity. In the case of multiple sclerosis (MS), the improvement of diagnostic efficacy depends on a careful analysis of the clinical presentation and the use of increasingly stringent MRI criteria aimed at improving the specificity of the conventional MRI T2 sequences. New sequences such as fast spin-echo (also called turbo spin-echo) and FLAIR (fluid attenuated inversion recovery, a method derived from inversion recovery) have improved the visualization of lesions. MRI can under certain conditions be used to monitor the evolution of MS. Acute-phase monitoring is focused on observed changes in disease activity such as the appearance, recurrence or extension of lesions after i.v. injection of contrast medium, i.e., gadolinium (Gd)-enhanced MRI. In the chronic phase, the lesions is the aspect used as the monitoring criterion. However, MRI is still only a secondary criterion in phase III therapeutic trials due to its insufficient correlation with the disability. In neurological daily practice, conventional MRI is only of limited interest at the individual level in patient follow-up, as its prognostic value is poor. Moreover, the difficulty in determining the lesion load can only be excluded in the context of clinical trials, in which certain methodological precautions are taken. This is why techniques other than MRI are being investigated to obtain a better correlation with the clinical course of the disease, for instance the quantification of 'black holes' on T1 weighted images, and the measurement of cerebral and spinal atrophy. Adapted MRI techniques allow a weighted signal to be obtained via the movement (diffusion imaging), by the complexity of the molecular structure (magnetization transfer imaging), by chemical shift (spectroscopic imaging), or by local oxygenation (functional MRI). These new MRI techniques allow a more precise assessment of the pathological mechanisms involved in MS, such as edema, blood brain barrier break-down, demyelinisation, gliosis, cellular infiltration and axonal loss; they provide a better means of establishing the correlation between clinical impact and the destructive nature of the MS lesion. The importance of axonal loss has recently been confirmed in MS by analyzing MRI spectroscopic and neuropathological findings. In addition to magnetization transfer imaging, MR diffusion imaging and functional MRI are being intensively studied in order to assess their contribution to the study of reversibility of the degenerative process. PMID:10815291

Tourbah, A; Berry, I

2000-03-01

100

Magnetic resonance imaging in entomology: a critical review  

Microsoft Academic Search

Magnetic resonance imaging (MRI) enables in vivo imaging of organisms. The recent development of the magnetic resonance microscope (MRM) has enabled organisms within the size range of many insects to be imaged. Here, we introduce the principles of MRI and MRM and review their use in entomology. We show that MRM has been successfully applied in studies of parasitology, development,

Ratnieks F. L. W

101

Nuclear magnetic resonance imaging of the spine  

SciTech Connect

Forty subjects were examined to determine the accuracy and clinical usefulness of nuclear magnetic resonance (NMR) examination of the spine. The NMR images were compared with plain radiographs, high-resolution computed tomograms, and myelograms. The study included 15 patients with normal spinal cord anatomy and 25 patients whose pathological conditions included canal stenosis, herniated discs, metastatic tumors, primary cord tumor, trauma, Chiari malformations, syringomyelia, and developmental disorders. Saturation recovery images were best in differentiating between soft tissue and cerebrospinal fluid. NMR was excellent for the evaluation of the foramen magnum region and is presently the modality of choice for the diagnosis of syringomyelia and Chiari malformation. NMR was accurate in diagnosing spinal cord trauma and spinal canal block.

Modic, M.T.; Weinstein, M.A.; Pavlicek, W.; Starnes, D.L.; Duchesneau, P.M.; Boumphrey, F.; Hardy, R.J. Jr.

1984-01-01

102

Magnetic resonance imaging of atherosclerotic vascular disease.  

PubMed

Atherosclerosis is a chronic, progressive, and often widespread arterial disorder in which the morphology and composition of the arterial segments containing atheroma are of considerable importance. Magnetic resonance imaging (MRI) allows non-invasive assessment of early arterial disease without the use of ionizing radiation. Arterial compliance, flow-wave velocity, and the pattern of flow within the aorta may all be disturbed by the disease, but these parameters are all accessible to MRI. In addition, atheroma can be directly imaged. Thus, MRI is valuable not only in the detection of disease, but also in the study of its natural history and the effects of interventions such as the control of risk factors and the use of lipid-lowering agents. PMID:8297541

Underwood, R S; Mohiaddin, R H

1993-11-01

103

Bilateral filtering of magnetic resonance phase images.  

PubMed

High-pass filtering is required for the removal of background field inhomogeneities in magnetic resonance phase images. This high-pass filtering smooths across boundaries between areas with large differences in phase. The most prominent boundary is the surface of the brain where areas with large phase values inside the brain are located close to areas outside the brain where the phase is, on average, zero. Cortical areas, which are of great interest in brain MRI, are therefore often degraded by high-pass filtering. Here, we propose the use of the bilateral filter for the high-pass filtering step. The bilateral filter is essentially a Gaussian filter that stops smoothing at boundaries. We show that the bilateral filter improves image quality at the brain's surface, without sacrificing contrast within the brain. PMID:21664782

McPhee, Kelly C; Denk, Christian; Al-Rekabi, Zeinab; Rauscher, Alexander

2011-09-01

104

Magnetic resonance imaging after exposure to microgravity  

NASA Technical Reports Server (NTRS)

A number of physiological changes were demonstrated in bone, muscle, and blood from exposure of humans and animals to microgravity. Determining mechanisms and the development of effective countermeasures for long-duration space missions is an important NASA goal. Historically, NASA has had to rely on tape measures, x-ray, and metabolic balance studies with collection of excreta and blood specimens to obtain this information. The development of magnetic resonance imaging (MRI) offers the possibility of greatly extending these early studies in ways not previously possible; MRI is also non-invasive and safe; i.e., no radiation exposure. MRI provides both superb anatomical images for volume measurements of individual structures and quantification of chemical/physical changes induced in the examined tissues. This investigation will apply MRI technology to measure muscle, intervertebral disc, and bone marrow changes resulting from exposure to microgravity.

Leblanc, Adrian

1993-01-01

105

In vivo nuclear magnetic resonance imaging  

NASA Technical Reports Server (NTRS)

A number of physiological changes have been demonstrated in bone, muscle and blood after exposure of humans and animals to microgravity. Determining mechanisms and the development of effective countermeasures for long duration space missions is an important NASA goal. The advent of tomographic nuclear magnetic resonance imaging (NMR or MRI) gives NASA a way to greatly extend early studies of this phenomena in ways not previously possible; NMR is also noninvasive and safe. NMR provides both superb anatomical images for volume assessments of individual organs and quantification of chemical/physical changes induced in the examined tissues. The feasibility of NMR as a tool for human physiological research as it is affected by microgravity is demonstrated. The animal studies employed the rear limb suspended rat as a model of mucle atrophy that results from microgravity. And bedrest of normal male subjects was used to simulate the effects of microgravity on bone and muscle.

Leblanc, A.; Evans, H.; Bryan, R. N.; Johnson, P.; Schonfeld, E.; Jhingran, S. G.

1984-01-01

106

Endometriosis: the role of magnetic resonance imaging.  

PubMed

Several imaging options are available today to diagnose endometriosis. Currently, the two techniques most used are sonography and magnetic resonance imaging (MRI). Three-dimensional (3D) sonography has proved to be particularly sensitive in the diagnosis of endometriosis. In recent years, MRI has emerged as a high reproducible method to explore endometriosis; moreover, its capability to evaluate tissue signal is an extremely powerful system in the differential diagnosis with other pathologies and for the identification of malignant degeneration. The purpose of this paper is to present the state-of-the-art of MRI of endometriosis by performing a review of the literature and showing the epidemiology, pathogenesis, and classification of endometriosis. In this work, the technique that should be used, MR findings of endometriosis and the principles of differential diagnosis are explained. PMID:24676084

Saba, Luca; Sulcis, Rosa; Melis, Gian Benedetto; Cecco, Carlo Nicola de; Laghi, Andrea; Piga, Mario; Guerriero, Stefano

2014-03-27

107

[Magnetic resonance imaging of cardiovascular thrombi].  

PubMed

Magnetic resonance imaging (MRI) was performed for 10 patients with cardiovascular thrombi using a 0.1-Tesla resistive type apparatus (ASAHI MARK-J). In all cases thrombi were clearly imaged by NMR and their shapes closely resembled those imaged by X-ray CT. Mural thrombi located within left ventricular aneurysms of two patients with old anteroseptal myocardial infarction were semilunar in form. A mural thrombus in the right ventricle of a patient with cardiovascular Behcet's disease was also clearly imaged. Mural thrombi within the enlarged left atrium of two patients with mitral valve stenosis and insufficiency were clearly demonstrated in both cross- and longitudinal sections. In three patients with thoracic aortic aneurysm, mural thrombi were recognized within the local dilatations of the aorta. In two patients with dissecting aortic aneurysm, mural thrombi were visualized within false lumen using MRI. Mean T1 values and standard deviations for the left ventricular cavity, the left ventricular wall, and the thrombi were 639 +/- 49, 349 +/- 17 and 316 +/- 84 msec, respectively. Mean T1 values of the thrombi were usually shorter than those of the left ventricular wall. Some supposedly fresh thrombi had longer T1 values, however. PMID:3837061

Imai, H; Sakakibara, M; Yoshida, K; Watanabe, S; Masuda, Y; Inagaki, Y; Ikehira, H; Fukuda, N; Tateno, Y

1985-09-01

108

Methods for chemical exchange saturation transfer magnetic resonance imaging  

E-print Network

Chemical exchange saturation transfer (CEST) is a relatively new magnetic resonance imaging (MRI) acquisition technique that generates contrast dependent on tissue microenvironment, such as protein concentration and ...

Scheidegger, Rachel Nora

2013-01-01

109

Multimodal neuroimaging integrating functional magnetic resonance Imaging and electroencephalography.  

E-print Network

??Functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) are two widely used neuroimaging modalities with complementary merits and limitations. FMRI has low temporal resolution but… (more)

Liu, Zhongming

2009-01-01

110

Use of contrast agents in oncological imaging: magnetic resonance imaging  

PubMed Central

Abstract Magnetic resonance plays a leading role in the management of oncology patients, providing superior contrast resolution and greater sensitivity compared with other techniques, which enables more accurate tumor identification, characterization and staging. Contrast agents are widely used in clinical magnetic resonance imaging; approximately 40–50% of clinical scans are contrast enhanced. Most contrast agents are based on the paramagnetic gadolinium ion Gd3+, which is chelated to avoid the toxic effects of free gadolinium. Multiple factors such as molecule structure, molecule concentration, dose, field strength and temperature determine the longitudinal and transverse relaxation rates (R1 and R2, respectively) and thus the T1- and T2-relaxivities of these chelates. These T1- and T2-relaxivities, together with their pharmacokinetic properties (i.e. distribution and concentration in the area of interest), determine the radiologic efficacy of the gadolinium-based contrast agents. PMID:24060901

Cugini, Christian; Scatto, Giuliano; Zanato, Riccardo; Fusaro, Michele; Dorigo, Alberto

2013-01-01

111

Designing and characterizing hyperpolarizable silicon nanoparticles for magnetic resonance imaging  

E-print Network

Magnetic Resonance Imaging (MRI) is one of the most powerful noninvasive tools for diagnosing human disease, but its utility is limited because current contrast agents are ineffective when imaging air-tissue interfaces, ...

Anahtar, Melis Nuray

2008-01-01

112

Magnetic resonance imaging of glioblastoma using aptamer conjugated magnetic nanoparticles  

NASA Astrophysics Data System (ADS)

Here we introduce a new class of smart imaging probes hybridizing polysorbate 80 coated-magnetic nanoparticles with vascular endothelial growth factor receptor 2 (VEGFR2)-targetable aptamer for specific magnetic resonance (MR) imaging of angiogenesis from glioblastoma.

Kim, Bongjune; Yang, Jaemoon; Hwang, Myeonghwan; Suh, Jin-Suck; Huh, Yong-Min; Haam, Seungjoo

2012-10-01

113

Functional magnetic resonance imaging of the lung.  

PubMed

Beyond being a substitute for X-ray, computed tomography, and scintigraphy, magnetic resonance imaging (MRI) inherently combines morphologic and functional information more than any other technology. Lung perfusion: The most established method is first-pass contrast-enhanced imaging with bolus injection of gadolinium chelates and time-resolved gradient-echo (GRE) sequences covering the whole lung (1 volume/s). Images are evaluated visually or semiquantitatively, while absolute quantification remains challenging due to the nonlinear relation of T1-shortening and contrast material concentration. Noncontrast-enhanced perfusion imaging is still experimental, either based on arterial spin labeling or Fourier decomposition. The latter is used to separate high- and low-frequency oscillations of lung signal related to the effects of pulsatile blood flow. Lung ventilation: Using contrast-enhanced first-pass perfusion, lung ventilation deficits are indirectly identified by hypoxic vasoconstriction. More direct but still experimental approaches use either inhalation of pure oxygen, an aerosolized contrast agent, or hyperpolarized noble gases. Fourier decomposition MRI based on the low-frequency lung signal oscillation allows for visualization of ventilation without any contrast agent. Respiratory mechanics: Time-resolved series with high background signal such as GRE or steady-state free precession visualize the movement of chest wall, diaphragm, mediastinum, lung tissue, tracheal wall, and tumor. The assessment of volume changes allows drawing conclusions on regional ventilation. With this arsenal of functional imaging capabilities at high spatial and temporal resolution but without radiation burden, MRI will find its role in regional functional lung analysis and will therefore overcome the sensitivity of global lung function analysis for repeated short-term treatment monitoring. PMID:24481761

Biederer, J; Heussel, C P; Puderbach, M; Wielpuetz, M O

2014-02-01

114

Magnetic Resonance Imaging of the Elbow  

PubMed Central

Context: The elbow is a complex joint and commonly injured in athletes. Evaluation of the elbow by magnetic resonance imaging (MRI) is an important adjunct to the physical examination. To facilitate accurate diagnosis, a concise structured approach to evaluation of the elbow by MRI is presented. Evidence Acquisition: A PubMed search was performed using the terms elbow and MR imaging. No limits were set on the range of years searched. Articles were reviewed for relevance with an emphasis of the MRI appearance of normal anatomy and common pathology of the elbow. Results: The spectrum of common elbow disorders varies from obvious acute fractures to chronic overuse injuries whose imaging manifestations can be subtle. MRI evaluation should include bones; lateral, medial, anterior, and posterior muscle groups; the ulnar and radial collateral ligaments; as well as nerves, synovium, and bursae. Special attention should be paid to the valgus extension overload syndrome and the MRI appearance of associated injuries when evaluating throwing athletes. Conclusion: MRI evaluation of the elbow should follow a structured approach to facilitate thoroughness, accuracy, and speed. Such an approach should cover bone, cartilage, muscle, tendons, ligaments, synovium, bursae, and nerves. PMID:24381699

Sampath, Srinath C.; Sampath, Srihari C.; Bredella, Miriam A.

2013-01-01

115

Magnetic Resonance Imaging of the Knee  

PubMed Central

Context: Magnetic resonance imaging (MRI) affords high-resolution visualization of the soft tissue structures (menisci, ligaments, cartilage, etc) and bone marrow of the knee. Evidence Acquisition: Pertinent clinical and research articles in the orthopaedic and radiology literature over the past 30 years using PubMed. Results: Ligament tears can be accurately assessed with MRI, but distinguishing partial tears from ruptures of the anterior cruciate ligament (ACL) can be challenging. Determining the extent of a partial tear is often extremely difficult to accurately assess. The status of the posterolateral corner structures, menisci, and cartilage can be accurately evaluated, although limitations in the evaluation of certain structures exist. Patellofemoral joint, marrow, tibiofibular joint, and synovial pathology can supplement physical examination findings and provide definitive diagnosis. Conclusions: MRI provides an accurate noninvasive assessment of knee pathology. PMID:24381701

Hash, Thomas W.

2013-01-01

116

Cranial magnetic resonance imaging findings in kwashiorkor.  

PubMed

Protein energy malnutrition (PEM) is an important public health problem in the developing countries, although it is becoming uncommon in South West Nigeria. Cerebral changes have been associated with severe PEM. This study evaluated the neurological changes using Magnetic Resonance Imaging (MRI) in Ibadan south west Nigeria. The 5 children evaluated had a median age of 16 months and all the children had brain changes compatible with cerebral atrophy. In addition two of the children had periventricular white matter changes, while one these two had mega cisterna magna in addition. Though this study did not re-evaluate the brains of these children after nutritional rehabilitation, it is possible that changes are reversible as demonstrated in earlier studies. PMID:20128668

Atalabi, Omolola Mojisola; Lagunju, Ikeoluwa Abiola; Tongo, Olukemi Oluwatoyin; Akinyinka, Olusegun Olusina

2010-01-01

117

Fetal magnetic resonance imaging in obstetric practice  

PubMed Central

Ultrasonography (USG) is the primary imaging method for prenatal diagnosis of fetal abnormalities since its discovery. Although it is the primary method of fetal imaging, it cannot provide sufficient information about the fetus in some conditions such as maternal obesity, oligohydramnios and engagement of the fetal head. At this stage, magnetic resonance imaging (MRI) facilitates examination by providing more specific information. The need and importance of fetal MRI applications further increased by the intrauterine surgery which is currently gaining popularity. Some advantages of fetal MRI over USG are the good texture of contrast, a greater study area and visualization of the lesion and neighbourhood relations, independence of the operators. Also it is not affected by maternal obesity and severe oligohydramnios. However, MRI is inadequate in detecting fetal limb and cardiac abnormalities when compared to USG. MRI is not used routinely in pregnancy. It is used in situations where nonionizing imaging methods are inadequate or ionizing radiation is required in pregnant women. It is not recommended during the first trimester. Contrast agent (Godalinium) is not used during pregnancy. It is believed that MRI is not harmful to the fetus, although the biological risk of MRI application is not known. MRI technique is superior to USG in the detection of corpus callosum dysgenesis, third-trimester evaluation of posterior fossa malformations, bilateral renal agenesis, diaphragmatic hernia and assessment of lung maturation. Especially, it is the method of choice for evaluation of central nervous system (CNS) abnormalities. Fetal MRI has a complementary role with USG. It provides important information for prenatal diagnosis, increases diagnostic accuracy, and in turn affects the prenatal treatment, prenatal interventions and birth plan. PMID:24591956

Kö?ü?, Ayd?n; Kö?ü?, Nermin; Usluo?ullar?, Betül; Duran, Müzeyyen; Turhan, Nilgün Öztürk; Tek?am, Mehmet

2011-01-01

118

Small Animal Imaging with Magnetic Resonance Microscopy  

PubMed Central

Small animal magnetic resonance microscopy (MRM) has evolved significantly from testing the boundaries of imaging physics to its expanding use today as a tool in non-invasive biomedical investigations. This review is intended to capture the state-of-the-art in MRM for scientists who may be unfamiliar with this modality, but who want to apply its capabilities to their research. We therefore include a brief review of MR concepts and methods of animal handling and support before covering a range of MRM applications including the heart, lung, brain, and the emerging field of MR histology. High-resolution anatomical imaging reveals increasingly exquisite detail in healthy animals and subtle architectural aberrations that occur in genetically altered models. Resolution of 100 µm in all dimensions is now routinely attained in living animals, and 10 µm3 is feasible in fixed specimens. Such images almost rival conventional histology while allowing the object to be viewed interactively in any plane. MRM is now increasingly used to provide functional information in living animals. Images of the beating heart, breathing lung, and functioning brain can be recorded. While clinical MRI focuses on diagnosis, MRM is used to reveal fundamental biology or to non-invasively measure subtle changes in the structure or function of organs during disease progression or in response to experimental therapies. The ability of MRM to provide a detailed functional and anatomical picture in rats and mice, and to track this picture over time, makes it a promising platform with broad applications in biomedical research. PMID:18172332

Driehuys, Bastiaan; Nouls, John; Badea, Alexandra; Bucholz, Elizabeth; Ghaghada, Ketan; Petiet, Alexandra; Hedlund, Laurence W.

2009-01-01

119

Magnetic Resonance Imaging as a Tool to Predict Meniscal Reparability  

Microsoft Academic Search

One hundred six patients who underwent high field strength magnetic resonance imaging and subsequent arthroscopy of the knee were evaluated to determine the accuracy of magnetic resonance imaging in predicting meniscal tear reparability. Each scan was independently read by three examiners with varying degrees of expertise: a musculoskeletal radiologist, a senior orthopaedic surgeon, and a general radiologist. Each suspected tear

Matthew J. Matava; Kevin Eck; William Totty; Rick W. Wright; Robert A. Shively

1999-01-01

120

Surface Plasmon Resonance Imaging Studies of Protein-Carbohydrate Interactions  

E-print Network

Surface Plasmon Resonance Imaging Studies of Protein-Carbohydrate Interactions Emily A. Smith; E-mail: corn@chem.wisc.edu; kiessling@chem.wisc.edu Abstract: Carbohydrate arrays fabricated on gold films were used to study carbohydrate-protein interactions with surface plasmon resonance (SPR) imaging

121

Magnetic Resonance Imaging of Electroconvection in a Polar Organic Solvent  

E-print Network

Magnetic Resonance Imaging of Electroconvection in a Polar Organic Solvent Scott A. Riley, California 95616 Received October 20, 1999; revised February 2, 2000 Molecular motion in the polar organic solvent nitrobenzene induced by an electric field is studied by magnetic resonance imaging. Rf pulse

Augustine, Mathew P.

122

Magnetic resonance imaging of brain function and neurochemistry  

Microsoft Academic Search

In the past decade, magnetic resonance imaging (MRI) research has been focused on the acquisition of physiological and biochemical information noninvasively. Probably the most notable accomplishment in this general effort has been the introduction of the MR approaches to map brain function. This capability, often referred to as functional magnetic resonance imaging, or fMRI, is based on the sensitivity of

KAMIL UGURBIL; DAE-SHIK KIM; TIM DUONG; XIAOPING HU; SEIJI OGAWA; ROLF GRUETTER; WEI CHEN; SEONG-GI KIM; XIAO-HUNG ZHU; ESSA YACOUB; PIERRE-FRANCOIS VAN DE MOORTELE; AMIR SHMUEL; JOSEF PFEUFFER; HELLMUT MERKLE; PETER ANDERSEN; GREGOR ADRIANY

2001-01-01

123

Magnetic resonance imaging of the skin.  

PubMed

A thorough examination of the skin is essential to screen various diseases accurately, evaluate the effectiveness of topically applied drugs and assess the results of dermatological surgeries such as skin grafts. The assessment of skin properties is also crucial in the cosmetics industry, where it is important to evaluate the effects skin care products have on these properties. The simplest and most widely used method of skin evaluation, the 'naked eye' assessment, enables researchers to assess only the skin surface and involves a large amount of inter-observer variability. Thanks to a great progress that has been made in physics, electronics and computer engineering in recent years, sophisticated imaging methods are increasingly available in day-to-day studies. The aim of this review was to present one of these techniques, namely the magnetic resonance imaging (MRI), and to discuss its possible use in skin examination and analysis. We present basic principles of MRI, as well as several interesting applications in the field of dermatology, and discuss the advantages and limitations of this method. PMID:20180890

Stefanowska, J; Zakowiecki, D; Cal, K

2010-08-01

124

Monitoring tissue engineering using magnetic resonance imaging.  

PubMed

Assessment of tissue regeneration is essential to optimize the stages of tissue engineering (cell proliferation, tissue development and implantation). Optical and X-ray imaging have been used in tissue engineering to provide useful information, but each has limitations: for example, poor depth penetration and radiation damage. Magnetic resonance imaging (MRI) largely overcomes these restrictions, exhibits high resolution (approximately 100 microm) and can be applied both in vitro and in vivo. Recently, MRI has been used in tissue engineering to generate spatial maps of tissue relaxation times (T(1), T(2)), water diffusion coefficients, and the stiffness (shear moduli) of developing engineered tissues. In addition, through the use of paramagnetic and superparamagnetic contrast agents, MRI can quantify cell death, assess inflammation, and visualize cell trafficking and gene expression. After tissue implantation MRI can be used to observe the integration of a tissue implant with the surrounding tissues, and to check for early signs of immune rejection. In this review, we describe and evaluate the growing role of MRI in the assessment of tissue engineered constructs. First, we briefly describe the underlying principles of MRI and the expected changes in relaxation times (T(1), T(2)) and the water diffusion coefficient that are the basis for MR contrast in developing tissues. Next, we describe how MRI can be applied to evaluate the tissue engineering of mesenchymal tissues (bone, cartilage, and fat). Finally, we outline how MRI can be used to monitor tissue structure, composition, and function to improve the entire tissue engineering process. PMID:19134545

Xu, Huihui; Othman, Shadi F; Magin, Richard L

2008-12-01

125

Magnetic resonance velocimetry: applications of magnetic resonance imaging in the measurement of fluid motion  

Microsoft Academic Search

Magnetic resonance velocimetry (MRV) is a non-invasive technique capable of measuring the three-component mean velocity field in complex three-dimensional geometries with either steady or periodic boundary conditions. The technique is based on the phenomenon of nuclear magnetic resonance (NMR) and works in conventional magnetic resonance imaging (MRI) magnets used for clinical imaging. Velocities can be measured along single lines, in

Christopher J. Elkins; Marcus T. Alley

2007-01-01

126

Magnetic resonance velocimetry: applications of magnetic resonance imaging in the measurement of fluid motion  

Microsoft Academic Search

Magnetic resonance velocimetry (MRV) is a non-invasive technique capable of measuring the three-component mean velocity field\\u000a in complex three-dimensional geometries with either steady or periodic boundary conditions. The technique is based on the\\u000a phenomenon of nuclear magnetic resonance (NMR) and works in conventional magnetic resonance imaging (MRI) magnets used for\\u000a clinical imaging. Velocities can be measured along single lines, in

Christopher J. Elkins; Marcus T. Alley

2007-01-01

127

Roadmap: Radiologic Imaging Sciences Magnetic Resonance Imaging (with certification and ATS Radiologic Technology) -  

E-print Network

Roadmap: Radiologic Imaging Sciences ­ Magnetic Resonance Imaging (with certification and ATS Radiologic Technology) - Bachelor of Radiologic Imaging Sciences Technology [RE-BRIT-RIS-MRHA] Regional in radiologic technology; successfully completed the certification exam for the American Registry of Radiologic

Sheridan, Scott

128

Real-time magnetic resonance imaging investigation of resonance tuning in soprano singing  

PubMed Central

This article investigates using real-time magnetic resonance imaging the vocal tract shaping of 5 soprano singers during the production of two-octave scales of sung vowels. A systematic shift of the first vocal tract resonance frequency with respect to the fundamental is shown to exist for high vowels across all subjects. No consistent systematic effect on the vocal tract resonance could be shown across all of the subjects for other vowels or for the second vocal tract resonance. PMID:21110548

Bresch, Erik; Narayanan, Shrikanth

2010-01-01

129

Functional magnetic resonance imaging at 0.2 Tesla  

Microsoft Academic Search

Functional magnetic resonance imaging of healthy human volunteers was carried out at 0.2 T, using proton-density weighted (TE = 24 ms) spin-echo imaging, in order to eliminate any contribution from the blood oxygenation-level dependent (BOLD) effect. The purpose of the study was to verify the existence of a proton-density change contribution to spin-echo functional magnetic resonance imaging (fMRI) data. Results

P. W Stroman; K. L Malisza; M Onu

2003-01-01

130

Combined magnetic resonance imaging and spectroscopic imaging approach to molecular imaging of prostate cancer  

Microsoft Academic Search

Magnetic resonance spectroscopic imaging (MRSI) provides a noninvasive method of detecting small molecular mark- ers (historically the metabolites choline and citrate) within the cytosol and extracellular spaces of the prostate, and is performed in conjunction with high-resolution anatomic imaging. Recent studies in pre-prostatectomy patients have indicated that the metabolic information provided by MRSI combined with the anatomical information provided by

John Kurhanewicz; Mark G. Swanson; Sarah J. Nelson; Daniel B. Vigneron

2002-01-01

131

Imaging of tophaceous gout: computed tomography provides specific images compared with magnetic resonance imaging and ultrasonography  

Microsoft Academic Search

Objective: To determine the usefulness of computed tomography (CT), magnetic resonance imaging (MRI), and Doppler ultrasonography (US) in providing specific images of gouty tophi.Methods: Four male patients with chronic gout with tophi affecting the knee joints (three cases) or the olecranon processes of the elbows (one case) were assessed. Crystallographic analyses of the synovial fluid or tissue aspirates of the

J C Gerster; M Landry; L Dufresne; J Y Meuwly

2002-01-01

132

Magnetic Resonance Imaging in Postprostatectomy Radiotherapy Planning  

SciTech Connect

Purpose: To investigate whether the use of magnetic resonance imaging (MRI) in prostate bed treatment planning could influence definition of the clinical target volume (CTV) and organs at risk. Methods and Materials: A total of 21 consecutive patients referred for prostate bed radiotherapy were included in the present retrospective study. The CTV was delineated according to the European Organization for Research and Treatment of Cancer recommendations on computed tomography (CT) and T{sub 1}-weighted (T{sub 1}w) and T{sub 2}-weighted (T{sub 2}w) MRI. The CTV magnitude, agreement, and spatial differences were evaluated on the planning CT scan after registration with the MRI scans. Results: The CTV was significantly reduced on the T{sub 1}w and T{sub 2}w MRI scans (13% and 9%, respectively) compared with the CT scans. The urinary bladder was drawn smaller on the CT scans and the rectum was smaller on the MRI scans. On T{sub 1}w MRI, the rectum and urinary bladder were delineated larger than on T{sub 2}w MRI. Minimal agreement was observed between the CT and T{sub 2}w images. The main spatial differences were measured in the superior and superolateral directions in which the CTV on the MRI scans was 1.8-2.9 mm smaller. In the posterior and inferior border, no difference was seen between the CT and T{sub 1}w MRI scans. On the T{sub 2}w MRI scans, the CTV was larger in these directions (by 1.3 and 1.7 mm, respectively). Conclusions: The use of MRI in postprostatectomy radiotherapy planning resulted in a reduction of the CTV. The main differences were found in the superior part of the prostate bed. We believe T{sub 2}w MRI enables more precise definition of prostate bed CTV than conventional planning CT.

Sefrova, Jana, E-mail: sefrova@post.cz [Department of Oncology and Radiotherapy, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic); Odrazka, Karel [Department of Clinical and Radiation Oncology, Multiscan and Pardubice Regional Hospital, Pardubice (Czech Republic); First and Third Faculty of Medicine, Charles University in Prague, Prague (Czech Republic); Paluska, Petr [Department of Oncology and Radiotherapy, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic); Belobradek, Zdenek [Department of Radiology, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic); Brodak, Milos [Department of Urology, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic); Dolezel, Martin [Department of Clinical and Radiation Oncology, Multiscan and Pardubice Regional Hospital, Pardubice (Czech Republic); First and Third Faculty of Medicine, Charles University in Prague, Prague (Czech Republic); Prosvic, Petr [Department of Urology, Regional Hospital Nachod, Nachod (Czech Republic); Macingova, Zuzana; Vosmik, Milan [Department of Oncology and Radiotherapy, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic); Hoffmann, Petr [Department of Radiology, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic); Louda, Miroslav [Department of Urology, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic); Nejedla, Anna [Department of Oncology and Radiotherapy, University Hospital Hradec Kralove, Hradec Kralove (Czech Republic)

2012-02-01

133

Magnetic resonance imaging evaluation of myocardial perfusion.  

PubMed

Noninvasive qualitative/quantitative assessment of myocardial perfusion is considered to be fundamental in the management of known and suspected coronary artery disease patients, as shown by the widespread utilization of thallium-201- and technetium-99m-labeled agents in myocardial single-photon emission computed tomography (SPECT) scintigraphy for diagnostic as well as prognostic purposes. Recently, the availability of subsecond ultrafast magnetic resonance imaging (MRI) sequences (FLASH, TurboFLASH, EPI) has provided new avenues for assessing myocardial perfusion by MRI in conjunction with contrast-agent bolus administration (contrast-enhanced first-pass MRI). MRI contrast agents can be classified into relaxation agents (T1 "positive") and susceptibility agents (T2 star [T2*] "negative"). All the commercially available MRI contrast agents used in clinical practice are relaxation agents employing the T1 shortening effect of metal ions like gadolinium (paramagnetism), thus producing a tissue signal-intensity increase on T1-weighted images (positive enhancement). On the other hand, T2* agents induce mainly susceptibility effects, i.e., rapid dephasing of spins with resultant signal loss on T2*-sensitive sequences (negative enhancement). Unfortunately, both relaxation and susceptibility agents are, by definition, "extracellular" contrast media, as they rapidly diffuse into the interstitial space, thus hampering the simple application of indicator-dilution kinetics for myocardial perfusion assessment. Blood pool agents are therefore needed to obtain predictable relations between the concentration of contrast medium in the myocardium and the change in signal intensity. In addition, newer MRI techniques for tissue perfusion quantitation have been recently reported, based on blood-sensitive sequences, thus without intravenous contrast administration. PMID:9662231

Passariello, R; De Santis, M

1998-06-18

134

Magnetic resonance imaging: Review of imaging techniques and overview of liver imaging  

PubMed Central

Magnetic resonance imaging (MRI) of the liver is slowly transitioning from a problem solving imaging modality to a first line imaging modality for many diseases of the liver. The well established advantages of MRI over other cross sectional imaging modalities may be the basis for this transition. Technological advancements in MRI that focus on producing high quality images and fast imaging, increasing diagnostic accuracy and developing newer function-specific contrast agents are essential in ensuring that MRI succeeds as a first line imaging modality. Newer imaging techniques, such as parallel imaging, are widely utilized to shorten scanning time. Diffusion weighted echo planar imaging, an adaptation from neuroimaging, is fast becoming a routine part of the MRI liver protocol to improve lesion detection and characterization of focal liver lesions. Contrast enhanced dynamic T1 weighted imaging is crucial in complete evaluation of diseases and the merit of this dynamic imaging relies heavily on the appropriate timing of the contrast injection. Newer techniques that include fluoro-triggered contrast enhanced MRI, an adaptation from 3D MRA imaging, are utilized to achieve good bolus timing that will allow for optimum scanning. For accurate interpretation of liver diseases, good understanding of the newer imaging techniques and familiarity with typical imaging features of liver diseases are essential. In this review, MR sequences for a time efficient liver MRI protocol utilizing newer imaging techniques are discussed and an overview of imaging features of selected common focal and diffuse liver diseases are presented. PMID:21160685

Maniam, Santhi; Szklaruk, Janio

2010-01-01

135

Diagnosis of orbital myositis by nuclear magnetic resonance imaging.  

PubMed Central

Two cases of orbital myositis are reported in which precise identification of the involved muscle was possible with the use of surface coil nuclear magnetic resonance (NMR) imaging. A clinical response to oral steroids in both cases coincided with a marked reduction in the abnormal thickening of the muscles as seen on the NMR images. Images PMID:3814571

Dua, H S; Smith, F W; Singh, A K; Forrester, J V

1987-01-01

136

Quantifying Mixing using Magnetic Resonance Imaging  

PubMed Central

Mixing is a unit operation that combines two or more components into a homogeneous mixture. This work involves mixing two viscous liquid streams using an in-line static mixer. The mixer is a split-and-recombine design that employs shear and extensional flow to increase the interfacial contact between the components. A prototype split-and-recombine (SAR) mixer was constructed by aligning a series of thin laser-cut Poly (methyl methacrylate) (PMMA) plates held in place in a PVC pipe. Mixing in this device is illustrated in the photograph in Fig. 1. Red dye was added to a portion of the test fluid and used as the minor component being mixed into the major (undyed) component. At the inlet of the mixer, the injected layer of tracer fluid is split into two layers as it flows through the mixing section. On each subsequent mixing section, the number of horizontal layers is duplicated. Ultimately, the single stream of dye is uniformly dispersed throughout the cross section of the device. Using a non-Newtonian test fluid of 0.2% Carbopol and a doped tracer fluid of similar composition, mixing in the unit is visualized using magnetic resonance imaging (MRI). MRI is a very powerful experimental probe of molecular chemical and physical environment as well as sample structure on the length scales from microns to centimeters. This sensitivity has resulted in broad application of these techniques to characterize physical, chemical and/or biological properties of materials ranging from humans to foods to porous media 1, 2. The equipment and conditions used here are suitable for imaging liquids containing substantial amounts of NMR mobile 1H such as ordinary water and organic liquids including oils. Traditionally MRI has utilized super conducting magnets which are not suitable for industrial environments and not portable within a laboratory (Fig. 2). Recent advances in magnet technology have permitted the construction of large volume industrially compatible magnets suitable for imaging process flows. Here, MRI provides spatially resolved component concentrations at different axial locations during the mixing process. This work documents real-time mixing of highly viscous fluids via distributive mixing with an application to personal care products. PMID:22314707

Tozzi, Emilio J.; McCarthy, Kathryn L.; Bacca, Lori A.; Hartt, William H.; McCarthy, Michael J.

2012-01-01

137

Quantifying mixing using magnetic resonance imaging.  

PubMed

Mixing is a unit operation that combines two or more components into a homogeneous mixture. This work involves mixing two viscous liquid streams using an in-line static mixer. The mixer is a split-and-recombine design that employs shear and extensional flow to increase the interfacial contact between the components. A prototype split-and-recombine (SAR) mixer was constructed by aligning a series of thin laser-cut Poly (methyl methacrylate) (PMMA) plates held in place in a PVC pipe. Mixing in this device is illustrated in the photograph in Fig. 1. Red dye was added to a portion of the test fluid and used as the minor component being mixed into the major (undyed) component. At the inlet of the mixer, the injected layer of tracer fluid is split into two layers as it flows through the mixing section. On each subsequent mixing section, the number of horizontal layers is duplicated. Ultimately, the single stream of dye is uniformly dispersed throughout the cross section of the device. Using a non-Newtonian test fluid of 0.2% Carbopol and a doped tracer fluid of similar composition, mixing in the unit is visualized using magnetic resonance imaging (MRI). MRI is a very powerful experimental probe of molecular chemical and physical environment as well as sample structure on the length scales from microns to centimeters. This sensitivity has resulted in broad application of these techniques to characterize physical, chemical and/or biological properties of materials ranging from humans to foods to porous media (1, 2). The equipment and conditions used here are suitable for imaging liquids containing substantial amounts of NMR mobile (1)H such as ordinary water and organic liquids including oils. Traditionally MRI has utilized super conducting magnets which are not suitable for industrial environments and not portable within a laboratory (Fig. 2). Recent advances in magnet technology have permitted the construction of large volume industrially compatible magnets suitable for imaging process flows. Here, MRI provides spatially resolved component concentrations at different axial locations during the mixing process. This work documents real-time mixing of highly viscous fluids via distributive mixing with an application to personal care products. PMID:22314707

Tozzi, Emilio J; McCarthy, Kathryn L; Bacca, Lori A; Hartt, William H; McCarthy, Michael J

2012-01-01

138

Fast magnetic resonance imaging of the lung  

Microsoft Academic Search

The impact of fast MR techniques developed for MR imaging of the lung will soon be recognized as equivalent to the high-resolution technique in chest CT imaging. In this article, the difficulties in MR imaging posed by lung morphology and its physiological motion are briefly introduced. Then, fast MR imaging techniques to overcome the problems of lung imaging and recent

Hiroto Hatabu; Qun Chen; Klaus W. Stock; Warren B. Gefter; Harumi Itoh

1999-01-01

139

Design algorithms for parallel transmission in magnetic resonance imaging  

E-print Network

The focus of this dissertation is on the algorithm design, implementation, and validation of parallel transmission technology in Magnetic Resonance Imaging (MRI). Novel algorithms are proposed which yield excellent excitation ...

Setsompop, Kawin

2008-01-01

140

LASER-POLARIZED 129Xe MAGNETIC RESONANCE SPECTROSCOPY AND IMAGING;  

E-print Network

LASER-POLARIZED 129Xe MAGNETIC RESONANCE SPECTROSCOPY AND IMAGING; THE DEVELOPMENT OF A METHOD.....................................................................13 2.2 Spin Exchange Polarization of 129 Xe......................................................................................19 3 129 Xe polarization and delivery system

Rosen, Matthew S

141

Improvements in magnetic resonance imaging excitation pulse design  

E-print Network

This thesis focuses on the design of magnetic resonance imaging (MRI) radio-frequency (RF) excitation pulses, and its primary contributions are made through connections with the novel multiple-system single-output (MSSO) ...

Zelinski, Adam Charles

2008-01-01

142

Magnetic Resonance Imaging Method For Estimating Cone Of Uncertainty  

Cancer.gov

The National Institute of Child Health and Human Development (NICHD), Section on Tissue Biophysics and Biomimetics, is seeking statements of capability or interest from parties interested in collaborative research to further develop, evaluate, or commercialize magnetic resonance imaging techniques.

143

Profile of compressive myelopathy as evaluated by magnetic resonance imaging.  

PubMed

To evaluate spectrum of diseases causing compressive myelopathy and accuracy of magnetic resonance imaging in diagnosing these conditions, a total of 69 clinically diagnosed cases of compressive myelopathy were evaluated by magnetic resonance imaging and results were tabulated. Caries spine was the commonest condition (24.6%) followed by metastasis spine (17.4%), ossified posterior longitudinal ligament (7.8%), primary bone tumours, nerve sheath tumours, intramedullary tumours and rare conditions like epidural abscess, spontaneous epidural haematoma, subdural haematoma, epidural lipomatosis, etc. Sensitivity, specificity and accuracy for diagnosing caries by magnetic resonance imaging was found to be 94%, 98% and 97% while that of metastasis spine was 91%, 98% and 97% respectively. Magnetic resonance imaging is the modality of choice for diagnosing compressive myelopathy. PMID:18705249

Yadav, Rohtas K; Agarwal, Shalini; Saini, Jitender

2008-02-01

144

Fast magnetic resonance spectroscopic imaging using RF coil arrays  

E-print Network

Conventional Magnetic Resonance Spectroscopic Imaging (MRSI) suffers from both low signal-to-noise (SNR), as well as long acquisition times. The development of high-fidelity gradient coils has opened opportunities for fast ...

Gagoski, Borjan Aleksandar

2006-01-01

145

Magnetic resonance imaging contrast agents for chemical sensing  

E-print Network

Magnetic resonance imaging (MRI) is frequently used for examining the human body. MRI contrast agents currently used in the clinic assist physicians in locating problematic areas, but other tools are needed to interrogate ...

Liu, Vincent Hok

2014-01-01

146

The Nobel Prize in Medicine for Magnetic Resonance Imaging  

ERIC Educational Resources Information Center

Nobel Prize in Medicine awarded in December 2003 to chemist Paul C. Lauterbur and physicist Peter Mansfield for the development of magnetic resonance imaging (MRI), a long overdue recognition of the huge impact MRI has had in medical diagnostics and research is mentioned. MRI was derived, and remains an extension of nuclear magnetic resonance

Fry, Charles G.

2004-01-01

147

Cranial and spinal magnetic resonance imaging: A guide and atlas  

SciTech Connect

This atlas provides a clinical guide to interpreting cranial and spinal magnetic resonance images. The book includes coverage of the cerebrum, temporal bone, and cervical, thoracic, and lumbar spine, with more than 400 scan images depicting both normal anatomy and pathologic findings. Introductory chapters review the practical physics of magnetic resonance (MR) imaging, offer guidelines for interpreting cranial MR scans, and provide coverage of each anatomic region of the cranium and spine. For each region, scans accompanied by captions, show normal anatomic sections matched with MR images. These are followed by MR scans depicting various disease states.

Daniels, D.L.; Haughton, V.M.

1987-01-01

148

Proton magnetic resonance imaging of lipid in pecan embryos  

Microsoft Academic Search

Magnetic resonance images of plant tissues typically are manifestations of water protons in tissues. Within oilseeds, however,\\u000a lipids contain a major portion of the mobile protons, which should enable specific imaging of lipids. In this study, experiments\\u000a were done to demonstrate spin-echo imaging (SEI) and chemical-shift imaging (CSI) of lipid within nonimbibed and imbibed embryos\\u000a of pecan (Carya illinoensis), a

John M. Halloina; Thomas G. Cooper; E. James Potchen; Tommy E. Thompson

1993-01-01

149

Real-Time Magnetic Resonance Imaging: Diagnostic and Interventional Applications  

Microsoft Academic Search

.   The advent of ultra-fast imaging techniques has extended the utility of magnetic resonance imaging (MRI) from a static and\\u000a purely diagnostic status to an imaging modality ideally suited for a number of therapeutic applications. These advances—along\\u000a with the recent development and refinement of miniature intravascular imaging catheters and MRI-compatible guidewires, balloon\\u000a catheters, and radiofrequency ablation catheters—have created an exciting

Albert C. Lardo

2000-01-01

150

Magnetic resonance stress imaging of myocardial perfusion and wall motion.  

PubMed

Cardiac magnetic resonance (CMR) imaging is a powerful tool for the detection and management of coronary artery disease. Beyond morphology, CMR imaging can probe relevant physiological parameters such as perfusion and function by means of stress testing. This article reviews current applications of CMR stress imaging with an emphasis upon vasodilators and positive inotropic agents. Further, technical aspects, image interpretation, diagnostic performance, and prognostic value of stress tests will be addressed. PMID:24157620

Kawel-Boehm, Nadine; Bremerich, Jens

2014-01-01

151

Magnetic resonance perfusion imaging in neuro-oncology  

PubMed Central

Abstract Recent advances in magnetic resonance imaging (MRI) have seen the development of techniques that allow quantitative imaging of a number of anatomical and physiological descriptors. These techniques have been increasingly applied to cancer imaging where they can provide some insight into tumour microvascular structure and physiology. This review details technical approaches and application of quantitative MRI, focusing particularly on perfusion imaging and its role in neuro-oncology. PMID:18980870

O’Connor, James; Thompson, Gerard; Mills, Samantha

2008-01-01

152

Advanced image reconstruction in parallel magnetic resonance imaging : constraints and solutions.  

E-print Network

Imaging speed is a crucial consideration for magnetic resonance imaging (MRI). The speed of conventional MRI is limited by hardware performance and physiological safety measures. "Parallel" MRI is a new technique that ...

Yeh, Ernest Nanjung, 1975-

2005-01-01

153

Fundamental and practical limits to image acceleration in parallel magnetic resonance imaging  

E-print Network

Imaging speed in conventional magnetic resonance imaging (MRI) is limited by the performance of magnetic field gradients and the rate of power deposition in tissue. Parallel MRI techniques overcome these constraints by ...

Ohliger, Michael A

2005-01-01

154

Imaging of the hip joint. Computed tomography versus magnetic resonance imaging  

NASA Technical Reports Server (NTRS)

The authors reviewed the applications and limitations of computed tomography (CT) and magnetic resonance (MR) imaging in the assessment of the most common hip disorders. Magnetic resonance imaging is the most sensitive technique in detecting osteonecrosis of the femoral head. Magnetic resonance reflects the histologic changes associated with osteonecrosis very well, which may ultimately help to improve staging. Computed tomography can more accurately identify subchondral fractures than MR imaging and thus remains important for staging. In congenital dysplasia of the hip, the position of the nonossified femoral head in children less than six months of age can only be inferred by indirect signs on CT. Magnetic resonance imaging demonstrates the cartilaginous femoral head directly without ionizing radiation. Computed tomography remains the imaging modality of choice for evaluating fractures of the hip joint. In some patients, MR imaging demonstrates the fracture even when it is not apparent on radiography. In neoplasm, CT provides better assessment of calcification, ossification, and periosteal reaction than MR imaging. Magnetic resonance imaging, however, represents the most accurate imaging modality for evaluating intramedullary and soft-tissue extent of the tumor and identifying involvement of neurovascular bundles. Magnetic resonance imaging can also be used to monitor response to chemotherapy. In osteoarthrosis and rheumatoid arthritis of the hip, both CT and MR provide more detailed assessment of the severity of disease than conventional radiography because of their tomographic nature. Magnetic resonance imaging is unique in evaluating cartilage degeneration and loss, and in demonstrating soft-tissue alterations such as inflammatory synovial proliferation.

Lang, P.; Genant, H. K.; Jergesen, H. E.; Murray, W. R.

1992-01-01

155

Advances in cardiac magnetic resonance imaging of congenital heart disease.  

PubMed

Due to advances in cardiac surgery, survival of patients with congenital heart disease has increased considerably during the past decades. Many of these patients require repeated cardiovascular magnetic resonance imaging to assess cardiac anatomy and function. In the past decade, technological advances have enabled faster and more robust cardiovascular magnetic resonance with improved image quality and spatial as well as temporal resolution. This review aims to provide an overview of advances in cardiovascular magnetic resonance hardware and acquisition techniques relevant to both pediatric and adult patients with congenital heart disease and discusses the techniques used to assess function, anatomy, flow and tissue characterization. PMID:25552386

Driessen, Mieke M P; Breur, Johannes M P J; Budde, Ricardo P J; van Oorschot, Joep W M; van Kimmenade, Roland R J; Sieswerda, Gertjan Tj; Meijboom, Folkert J; Leiner, Tim

2015-01-01

156

Combining magnetic resonance imaging and ultrawideband radar: A new concept for multimodal biomedical imaging  

Microsoft Academic Search

Due to the recent advances in ultrawideband (UWB) radar technologies, there has been widespread interest in the medical applications of this technology. We propose the multimodal combination of magnetic resonance (MR) and UWB radar for improved functional diagnosis and imaging. A demonstrator was established to prove the feasibility of the simultaneous acquisition of physiological events by magnetic resonance imaging and

F. Thiel; M. Hein; U. Schwarz; J. Sachs; F. Seifert

2009-01-01

157

Automatic Segmentation of Adipose Tissue from Thigh Magnetic Resonance Images  

E-print Network

, such as connective, neu- ral, adipose, skeletal and muscle tissue. They pose various challenges to standard imageAutomatic Segmentation of Adipose Tissue from Thigh Magnetic Resonance Images Senthil Purushwalkam1, Manchester Metropolitan University, UK Abstract. Automatic segmentation of adipose tissue in thigh magnetic

Li, Baihua

158

Genetically encoded reporters for hyperpolarized xenon magnetic resonance imaging  

E-print Network

-resolution non-invasive observation of the anatomy and function of intact organisms. However, previous MRI- netic resonance imaging (MRI) routinely delivers non-invasive images of anatomy at high resolution2 and biocompatible element distributes rapidly into tissues such as the lungs9 , brain10 , heart and kidneys11

Schaffer, David V.

159

Magnetic resonance imaging of bovine ovaries in vitro  

Microsoft Academic Search

A sample of 20 bovine ovaries were imaged in vitro using nuclear magnetic resonance (NMR) techniques to determine the visibility of various physiologic structures. In particular, the possibility of using NMR imaging to differentiate atretic follicles from physiologically selected and ovulatory follicles was examined. Five of the 20 ovaries were preserved in formalin, whereas the remaining 15 were preserved in

G. E. Sarty; E. J. Kendall; R. A. Pierson

1996-01-01

160

Validation of a human vision model for image quality evaluation of fast interventional magnetic resonance imaging  

Microsoft Academic Search

Perceptual difference models (PDMs) have become popular for evaluating the perceived degradation of an image by a process such as compression. We used a PDM to evaluate interventional magnetic resonance imaging (iMRI) methods that rapidly acquire an image at the expense of some anticipated image degradation compared to a conventional slower diagnostic technique. In particular, we examined MR keyhole techniques

Kyle A. Salem; Jonathan S. Lewin; Andrik J. Aschoff; Jeffrey L. Duerk; David L. Wilson

2002-01-01

161

Magnetic resonance imaging of acute spinal cord injury  

Microsoft Academic Search

Magnetic resonance imaging of acute spinal cord injury is described. The traumatized cord segment was clearly shown as a hyperintensity in a T2-weighted image whereas it appeared as an isointensity in a moderately T1-weighted image. This different sensitivity may result from parenchymal hemorrhagic tissue and edematous changes due to direct trauma. Hyperintense tissue was also seen in the retro-pharyngeal and-tracheal

S. Kadoya; T. Nakamura; S. Kobayashi; I. Yamamoto

1987-01-01

162

Paramagnetic and ferromagnetic resonance imaging with a tip-on-cantilever magnetic resonance force microscope  

NASA Astrophysics Data System (ADS)

A magnetic resonance force microscope with a "tip-on-cantilever" configuration was used to compare imaging characteristics of paramagnetic and ferromagnetic samples. Three-dimensional electron paramagnetic resonance (EPR) imaging of diphenylpicrylhydrazil (DPPH) particles was accomplished by scanning the sample in two dimensions while stepping an external field. The EPR force map showed broad response reflecting the size and shape of the sample, allowing a three-dimensional real-space magnetization image to be successfully reconstructed. In contrast to the EPR case, ferromagnetic resonance imaging of a micron-scale yttrium iron garnet sample showed no significant line broadening despite the strong field gradient (˜10 G/?m). Two-dimensional force maps revealed spatial dependence of magnetostatic and magnetoelastic modes.

Wago, K.; Botkin, D.; Yannoni, C. S.; Rugar, D.

1998-05-01

163

Correlating Hemodynamic Magnetic Resonance Imaging with high-field Intracranial Vessel Wall Imaging in Stroke  

PubMed Central

Vessel wall magnetic resonance imaging at ultra-high field (7 Tesla) can be used to visualize vascular lesions noninvasively and holds potential for improving stroke-risk assessment in patients with ischemic cerebrovascular disease. We present the first multi-modal comparison of such high-field vessel wall imaging with more conventional (i) 3 Tesla hemodynamic magnetic resonance imaging and (ii) digital subtraction angiography in a 69-year-old male with a left temporal ischemic infarct. PMID:25426229

Langdon, Weston; Donahue, Manus J.; van der Kolk, Anja G.; Rane, Swati; Strother, Megan K.

2014-01-01

164

Magnetic Resonance Imaging in Lewy Body Dementias  

Microsoft Academic Search

Dementia with Lewy bodies (DLB) and Parkinson’s disease dementia (PDD) share common clinical, neuropsychological and pathological features. In clinical diagnosis, distinguishing between these conditions and other dementia subtypes such as Alzheimer’s disease (AD) can be difficult. Despite the development of consensus diagnostic criteria, sensitivity for diagnosis remains low, especially outside specialist centres. Neuroimaging techniques using magnetic resonance (MR) can assess

Rosie Watson; Andrew M. Blamire; John T. O’Brien

2009-01-01

165

Imaging Intelligence with Proton Magnetic Resonance Spectroscopy  

ERIC Educational Resources Information Center

Proton magnetic resonance spectroscopy ([to the first power]H-MRS) is a technique for the assay of brain neurochemistry "in vivo." N-acetylaspartate (NAA), the most prominent metabolite visible within the [to the first power]H-MRS spectrum, is found primarily within neurons. The current study was designed to further elucidate NAA-cognition…

Jung, Rex E.; Gasparovic, Charles; Chavez, Robert S.; Caprihan, Arvind; Barrow, Ranee; Yeo, Ronald A.

2009-01-01

166

Method for nuclear magnetic resonance imaging  

DOEpatents

A method for in vivo NMR imaging of the blood vessels and organs of a patient characterized by using a dark dye-like imaging substance consisting essentially of a stable, high-purity concentration of D/sub 2/O in a solution with water.

Kehayias, J.J.; Joel, D.D.; Adams, W.H.; Stein, H.L.

1988-05-26

167

[Diagnostic approach to cardiopathies by means of magnetic resonance imaging].  

PubMed

Cardiomyopathies encompass a broad spectrum of heart pathologies having a basic principle, the intrinsic injury of the myocardial fiber. By definition, cardiomyopathies could be primary (dilated cardiomyopathy), or can be a consequence of another cardiovascular illness (high blood pressure), or of genetic anomalies, such as hypertrophic cardiomyopathy, or due to alterations in myocytes due to fibrolipidic material as occurs in right ventricle arrhythmogenic dysplasia. Currently, magnetic resonance imaging is the best method to approach the diagnosis of these pathologies. Magnetic resonance imaging has allowed us to study histological sections through adequate sequences and using gadolinium as contrast agent. We present herein a simple way to approach the diagnosis of cardiomyopathies by means of magnetic resonance imaging methods. PMID:15909747

Gutiérrez Zamora, Agustín

2005-01-01

168

Magnetic resonance imaging of transplanted stem cell fate in stroke  

PubMed Central

Nowadays, scientific findings in the field of regeneration of nervous system have revealed the possibility of stem cell based therapies for damaged brain tissue related disorders like stroke. Furthermore, to achieve desirable outcomes from cellular therapies, one needs to monitor the migration, engraftment, viability, and also functional fate of transplanted stem cells. Magnetic resonance imaging is an extremely versatile technique for this purpose, which has been broadly used to study stroke and assessment of therapeutic role of stem cells. In this review we searched in PubMed search engine by using following keywords; “Stem Cells”, “Cell Tracking”, “Stroke”, “Stem Cell Transplantation”, “Nanoparticles”, and “Magnetic Resonance Imaging” as entry terms and based on the mentioned key words, the search period was set from 1976 to 2012. The main purpose of this article is describing various advantages of molecular and magnetic resonance imaging of stem cells, with focus on translation of stem cell research to clinical research. PMID:25097631

Aghayan, Hamid Reza; Soleimani, Masoud; Goodarzi, Parisa; Norouzi-Javidan, Abbas; Emami-Razavi, Seyed Hasan; Larijani, Bagher; Arjmand, Babak

2014-01-01

169

Diffusion tensor magnetic resonance image regularization  

Microsoft Academic Search

As multi-dimensional complex data become more common, new regularization schemes tailored to those data are needed. In this paper we present a scheme for regularising diffusion tensor magnetic resonance (DT-MR) data, and more generally multi-dimen- sional data defined by a direction map and one or several magnitude maps. The scheme is divided in two steps. First, a variational method is

Olivier Coulon; Daniel C. Alexander; Simon R. Arridge

2004-01-01

170

Magnetic resonance imaging findings in Axenfeld–Rieger syndrome  

PubMed Central

Axenfeld–Rieger syndrome (ARS) is a genetic disorder representing a disease spectrum resulting from neural crest cell maldevelopment. Glaucoma is a common complication from the incomplete formation of the iridocorneal angle structures. Neural crest cells also form structures of the forebrain and pituitary gland, dental papillae, aortic arch walls, genitalia, and long bones; therefore, patients with ARS manifest a wide range of systemic findings. To our knowledge, detailed magnetic resonance imaging findings have not been previously reported. We report a case of a 19-month-old Indian male diagnosed with ARS with emphasis on magnetic resonance imaging findings of the globes, brain, teeth, and skull base. PMID:23723681

Whitehead, Matthew T; Choudhri, Asim F; Salim, Sarwat

2013-01-01

171

Nuclear Magnetic Resonance (NMR) And Its Impact On Medical Imaging  

NASA Astrophysics Data System (ADS)

Not since the advent of x-ray transmission computed tomography a decade ago has an innovation in medical imaging generated as much interest as that currently directed to nuclear magnetic resonance. This technique, long a standby in chemistry and physics laboratories, promises to provide images of reasonable spatial resolution and exquisite contrast sensitivity. In addition, quantitative analysis of specific elements in selected regions of tissue may be possible. In developing a strategy for the acquisition of nuclear magnetic resonance, cost factors must be considered together with a realistic appraisal of a clinical facility as primarily a research or clinical unit.

Hendee, William R.

1982-12-01

172

Magnetic Resonance Imaging (MRI) (For Parents)  

MedlinePLUS

... child may be given headphones to listen to music or earplugs to block the noise and will ... Imaging (MRI): Cervical Spine Word! CT Scan or CAT Scan Medical Tests and Procedures (Video Landing Page) ...

173

Portable low-cost magnetic resonance imaging  

E-print Network

Purpose: As the premiere modality for brain imaging, MRI could find wider applicability if lightweight, portable systems were available for siting in unconventional locations such as intensive care units (ICUs), physician ...

Cooley, Clarissa Zimmerman

2014-01-01

174

High-field magnetic resonance imaging.  

PubMed

This article explores the role of high-field (HF) MR imaging in medicine. It analyzes advantages of HF MR imaging in application to human subjects and how best they can be used to unravel the secrets of diseases, such as multiple sclerosis. Special emphasis is placed on morphologic imaging to highlight the role of soft tissue contrast, MR spectroscopy to showcase the ability of detecting biochemical information, and functional MR imaging as an emerging technology for assessing tissue function with the possibility of eventual introduction to the clinical arena. In this article, hardware issues, such as RF coils for HF systems with a static magnetic field of 3.0 T or higher are also discussed. PMID:19064204

Kangarlu, Alayar

2009-02-01

175

Magnetic Resonance Molecular Imaging and Targeted Therapeutics  

Microsoft Academic Search

Advances in cellular and molecular biology are extending the horizons of medical imaging from gross anatomical description\\u000a toward delineation of cellular and biochemical signaling processes. The emerging fields of cellular and molecular imaging\\u000a aim to noninvasively diagnose disease based on the in vivo detection and characterization of complex pathological processes,\\u000a such as induction of inflammation or angiogenesis. Techniques have been

Anne Morawski Neubauer; Patrick Winter; Shelton Caruthers; Gregory Lanza; Samuel A. Wickline

176

Cardiovascular magnetic resonance imaging of coronary atherothrombosis  

Microsoft Academic Search

Summary  Atherothrombosis, defined as atherosclerotic lesion disruption with superimposed thrombus formation, is the major cause of\\u000a acute coronary syndromes and cardiovascular death. CMR imaging of coronary atherothrombosis is challenging because of the\\u000a small caliber of the vessels combined with respiratory and cardiac motion. Freebreathing 3D CMR coronary vessel wall imaging\\u000a has enabled in vivo quantification of coronary plaque burden and remodeling

W. Yong Kim; Elmar Spuentrup; Arno Buecker; Warren J. Manning; René M. Botnar

2005-01-01

177

He Lung Imaging in an Open Access, Very-Low-Field Human Magnetic Resonance Imaging System  

E-print Network

3 He Lung Imaging in an Open Access, Very-Low-Field Human Magnetic Resonance Imaging System R. W. Butler,6 F. W. Hersman,4 and R. L. Walsworth1 The human lung and its functions are extremely sensitive lung restrict sub- jects to lying horizontally. Imaging of human lungs using inhaled laser-polarized 3

Walsworth, Ronald L.

178

Roadmap: Radiologic Imaging Sciences -Magnetic Resonance Imaging (with AAS Radiologic Technology) -  

E-print Network

Roadmap: Radiologic Imaging Sciences - Magnetic Resonance Imaging (with AAS Radiologic Technology) - Bachelor of Radiologic and Imaging Sciences Technology [RE-BRIT-RIS-MRRT] Regional College Catalog Year Hours] Note: Students must have earned an AAS degree in Radiologic Technology (43 semester credits

Sheridan, Scott

179

Roadmap: Radiologic Imaging Sciences -Magnetic Resonance Imaging (with AAS Radiologic Technology) -  

E-print Network

Roadmap: Radiologic Imaging Sciences - Magnetic Resonance Imaging (with AAS Radiologic Technology) - Bachelor of Radiologic and Imaging Sciences Technology [RE-BRIT-RIS-MRRT] Regional College Catalog Year Hours] Note: Students must have earned an AAS degree in Radiologic Technology (69-71 semester credits

Sheridan, Scott

180

High resolution resonance ionization imaging detector and method  

DOEpatents

A resonance ionization imaging device (RIID) and method for imaging objects using the RIID are provided, the RIID system including a RIID cell containing an ionizable vapor including monoisotopic atoms or molecules, the cell being positioned to intercept scattered radiation of a resonance wavelength .lambda..sub.1 from the object which is to be detected or imaged, a laser source disposed to illuminate the RIID cell with laser radiation having a wavelength .lambda..sub.2 or wavelengths .lambda..sub.2, .lambda..sub.3 selected to ionize atoms in the cell that are in an excited state by virtue of having absorbed the scattered resonance laser radiation, and a luminescent screen at the back surface of the RIID cell which presents an image of the number and position of charged particles present in the RIID cell as a result of the ionization of the excited state atoms. The method of the invention further includes the step of initially illuminating the object to be detected or imaged with a laser having a wavelength selected such that the object will scatter laser radiation having the resonance wavelength .lambda..sub.1.

Winefordner, James D. (Gainesville, FL); Matveev, Oleg I. (Gainesville, FL); Smith, Benjamin W. (Gainesville, FL)

1999-01-01

181

Travelling Wave Magnetic Resonance Imaging at 3 Tesla  

E-print Network

Waveguides have been successfully used to generate magnetic resonance images at 7 T with whole-body systems. The bore limits the magnetic resonance signal transmitted because its specific cut-off frequency is greater than the majority of resonant frequencies. This restriction can be overcome by using a parallel-plate waveguide whose cut-off frequency is zero for the transversal electric modes and it can propagate any frequency. To investigate the potential benefits for whole-body imaging at 3 T, we compare numerical simulations at 1.5 T, 3 T, 7 T, and 9 T via the propagation of the parallel-plate waveguide principal mode filled with a cylindrical phantom and two surface coils. B1 mapping was computed to investigate the feasibility of this approach at 3T. The point spread function method was used to measure the imager performance for the traveling-wave magnetic resonance imaging experiment. Human leg images were acquired to experimentally validate this approach. The principal mode shows very little field magni...

Vazquez, F; Marrufo, O; Rodriguez, A O

2013-01-01

182

Portal biliopathy, magnetic resonance imaging and magnetic resonance cholangiopancreatography findings: a case series.  

PubMed

Portal biliopathy (PB) is a rare disorder, characterized by biliary ductal and gallbladder wall abnormalities seen in patients with portal hypertension. It most commonly occurs due to idiopathic extrahepatic portal vein obstruction (EHPVO). The abnormalities consist mainly of bile duct compression, stenoses, fibrotic strictures and dilation of both extrahepatic and intrahepatic bile ducts, as well as gallbladder varices. PB may mimic cholangiocarcinoma, sclerosing cholangitis, or choledocholithiasis. Misdiagnosis can be avoided using appropriate imaging modalities to prevent complications. We present the magnetic resonance imaging (MRI) and magnetic resonance cholangiography (MRCP) features of three patients with PB. PMID:25216728

Baskan, Ozdil; Erol, Cengiz; Sahingoz, Yusuf

2014-09-12

183

Basic principles of magnetic resonance imaging--an update.  

PubMed

Magnetic resonance (MR) imaging technology has undergone many technologic advances over the past few years. Many of these advances were stimulated by the wealth of information emerging from nuclear magnetic resonance research in the areas of new and optimal scanning methods and radio-frequency coil design. Other changes arose from the desire to improve image quality, ease siting restrictions and generally facilitate the clinical use of MR equipment. Many questions, however, remain unanswered. Perhaps the most controversial technologic question involves the optimal field strength required for imaging or spectroscopic applications or both. Other issues include safety and clinical efficacy. Technologic issues affect all aspects of MR use including the choice of equipment, examination procedure and image interpretation. Thus, an understanding of recent changes and their theoretic basis is necessary. PMID:3911591

Scherzinger, A L; Hendee, W R

1985-12-01

184

Basic principles of magnetic resonance imaging - an update  

SciTech Connect

Magnetic resonance (MR) imaging technology has undergone many technologic advances over the past few years. Many of these advances were stimulated by the wealth of information emerging from nuclear magnetic resonance research in the areas of new and optimal scanning methods and radio-frequency coil design. Other changes arose from the desire to improve image quality, ease siting restrictions and generally facilitate the clinical use of MR equipment. Many questions, however, remain unanswered. Perhaps the most controversial technologic question involves the optimal field strength required for imaging or spectroscopic applications or both. Other issues include safety and clinical efficacy. Technologic issues affect all aspects of MR use including the choice of equipment, examination procedure and image interpretation. Thus, an understanding of recent changes and their theoretic basis is necessary. 92 references, 10 figures, 1 table.

Scherzinger, A.L.; Hendee, W.R.

1985-12-01

185

Brain magnetic resonance imaging with contrast dependent on blood oxygenation  

SciTech Connect

Paramagnetic deoxyhemoglobin in venous blood is a naturally occurring contrast agent for magnetic resonance imaging (MRI). By accentuating the effects of this agent through the use of gradient-echo techniques in high yields, the authors demonstrate in vivo images of brain microvasculature with image contrast reflecting the blood oxygen level. This blood oxygenation level-dependent (BOLD) contrast follows blood oxygen changes induced by anesthetics, by insulin-induced hypoglycemia, and by inhaled gas mixtures that alter metabolic demand or blood flow. The results suggest that BOLD contrast can be used to provide in vivo real-time maps of blood oxygenation in the brain under normal physiological conditions. BOLD contrast adds an additional feature to magnetic resonance imaging and complement other techniques that are attempting to provide position emission tomography-like measurements related to regional neural activity.

Ogawa, S.; Lee, T.M.; Kay, A.R.; Tank, D.W. (AT and T Bell Laboratories, Murray Hill, NJ (United States))

1990-12-01

186

Patterned Resonance Plasmonic Microarrays for High-Performance SPR Imaging  

PubMed Central

We report a novel optical platform based on SPR generation and confinement inside a defined 3-dimensional microwell geometry that leads to background resonance-free SPR images. The array shows an exceptionally high signal-to-noise ratio (S/N>80) for imaging analysis and subnanometric thickness resolution. An angular sensitivity of 1 degree/0.01 RIU has been achieved and the signal to background ratio (S/B) improves to 20, one order of magnitude higher than best literature results. The design proves effective for probing supported lipid membrane arrays in real time with a thickness resolution of 0.24 nm and allows for imaging analysis of microfluidic circuits where resonant spots are separated by only one pixel (~ 7 ?m). The high image quality and unique chip geometry open up new avenues for array screening and biomicrofluidics using SPRi detection. PMID:21417424

Abbas, Abdennour; Linman, Matthew J.; Cheng, Quan

2011-01-01

187

Magnetic resonance imaging of the immature skeleton.  

PubMed

Magnetic resonance (MR) is unique in its ability to allow assessment of bone marrow, epiphyseal, physeal, and articular cartilage as well as tendons and ligaments. An understanding of skeletal maturation and the accompanying changes on MR is of utmost importance in pediatric radiology. In particular, it is important to recognize the normal spectrum related to ossification and marrow transformation. This review will include a brief description of main indications and common pitfalls in musculoskeletal MR in children. Also, we will focus on the MR appearance of the growing pediatric skeleton on the most commonly used sequences. PMID:24179233

Boavida, Peter; Muller, Lil-Sofie; Rosendahl, Karen

2013-11-01

188

The optic nerve pathology in magnetic resonance imaging.  

PubMed

Magnetic resonance imaging (MRI) delineates the orbital soft tissue excellently and is a valuable diagnostic tool in optic nerve pathology. By using different imaging parameters some examples are shown of demarcation of optic nerve tumors, optic nerve inflammations and orbital diseases surrounding the optic nerve. Whereas CT appears to be superior to MRI only in the detection of calcified perioptic meningiomas, MRI provides unique visualization of optic canal and even subarachnoidal space of retrobulbar optic nerve in peculiar cases. PMID:2079907

Wiegand, W

1990-01-01

189

The Underpinnings of the BOLD Functional Magnetic Resonance Imaging Signal  

Microsoft Academic Search

The good coverage and high resolution afforded by functional mag-netic resonance imaging (fMRI) make it an excellent tool for the noninvasive imaging of the human brain. Equally interesting, how-ever, is the use of this technique in animal studies using high mag-netic fields. In the latter case, highly spatiotemporally resolved fMRI can reveal how widespread neural networks are organized, and ac-companying

Nikos K. Logothetis

2003-01-01

190

Cerebral Hypoxia During Cardiopulmonary Bypass: A Magnetic Resonance Imaging Study  

Microsoft Academic Search

Background. Neurocognitive deficits after open heart operations have been correlated to jugular venous oxygen desaturation on rewarming from hypothermic cardiopulmonary bypass (CPB). Using a porcine model, we looked for evidence of cerebral hypoxia by magnetic resonance imaging during CPB. Brain oxygenation was assessed by T2?-weighted imaging, based on the blood oxygenation level-dependent effect (decreased T2?-weighted signal intensity with increased tissue

W. Alan C Mutch; Lawrence N Ryner; Piotr Kozlowski; Gordon Scarth; R. Keith Warrian; Gerald R Lefevre; Ted G Wong; Darren B Thiessen; Linda G Girling; Leonard Doiron; Chris McCudden; John K Saunders

1997-01-01

191

Open magnetic resonance imaging (MRI) scanners.  

PubMed

(1) In most MRI scanners, the patient examination table fits inside a long cylindrical tube. Large patients cannot be accommodated, and some persons experience claustrophobic reactions. Open MRI systems, in which the patient is placed between two plates, overcome these disadvantages. (2) Open MRI scanners are widely used in health care. High-field closed MRI systems are preferred for many examinations. (3) Early versions of open MRI scanners had low magnetic field strength, gave poorer image quality than most closed systems, and required longer examination times. Newer open scanners include machines with higher magnetic field strengths and improved image quality. (4) Closed high magnetic field scanners with short magnets and wide bore tubes offer improved comfort to patients, and may be an alternative to open scanners. (5) There is interest in using open systems for intra-operative and image-guided interventions. PMID:17086657

Hailey, D

2006-11-01

192

Image-based tracking of optically detunable parallel resonant circuits.  

PubMed

In this work strategies for the robust localization of parallel resonant circuits are investigated. These strategies are based on the subtraction of two images, which ideally differ in signal intensity at the positions of the devices only. To modulate their signal amplification, and thereby generate the local variations, the parallel resonant circuits are alternately detuned and retuned during the acquisition. The integration of photodiodes into the devices permits their fast optical switching. Radial and spiral imaging sequences are modified to provide the data for the two images in addition to those for a conventional image in the same acquisition time. The strategies were evaluated by phantom experiments with stationary and moving catheter-borne devices. In particular, rapid detuning and retuning during the sampling of single profiles is shown to lead to a robust localization. Moreover, this strategy eliminates most of the drawbacks usually associated with image-based tracking, such as low temporal resolution. Image-based tracking may thus become a competitive (if not superior) alternative to projection-based tracking of parallel resonant circuits. PMID:12768595

Eggers, Holger; Weiss, Steffen; Boernert, Peter; Boesiger, Peter

2003-06-01

193

The use of modern imaging techniques in the diagnosis and treatment planning of patients with orbital floor fractures  

PubMed Central

Summary Background Ocular motility impairment associated with orbital trauma may have several causes and manifest with various clinical symptoms. In some cases orbital reconstructive surgery can be very challenging and the results are often unsatisfactory. The use of modern imaging techniques aids proper diagnosis and surgical planning. Case Report The authors present the case of a 29-year-old male who sustained trauma to the left orbit. Orthoptic examination revealed limited supra- and infraduction of the left eye. The patient reported diplopia in upgaze and downgaze with primary position spared. Dynamic magnetic resonance imaging (dMRI) was performed, which revealed restriction of the left inferior rectus muscle in its central section. A patient-specific anatomical model was prepared on the basis of 3-dimensional computed tomography (CT) study of the intact orbit, which was used to prepare a custom pre-bent titanium mesh implant. The patient underwent reconstructive surgery of the orbital floor. Conclusions Modern imaging techniques such as dMRI and 3-dimensional CT reconstruction allow us to better understand the pathophysiology of orbital floor fractures and to precisely plan surgical treatment. PMID:21804469

Loba, Piotr; Kozakiewicz, Marcin; Elgalal, Marcin; Stefa?czyk, Ludomir; Broniarczyk-Loba, Anna; Omulecki, Wojciech

2011-01-01

194

Assessment of coronary artery stenosis by magnetic resonance imaging.  

PubMed Central

OBJECTIVE: The findings of magnetic resonance and x-ray angiography were compared for assessment of coronary artery stenosis in this validation study. BACKGROUND: Magnetic resonance angiography of the coronary arteries has recently been described, but there has been no comparison with x-ray angiography of localisation or assessment of important characteristics of coronary stenosis. METHODS: A breath hold, segmented k-space, 2D gradient echo imaging technique incorporating fat suppression was used in 39 patients (55 coronary stenoses) with known coronary artery disease. RESULTS: Overall, 47 stenoses (85%) were assessed by magnetic resonance (29 of 33 stenoses in the left anterior descending artery, one of one in the left main stem, 14 of 17 in the right coronary artery, and three of four in the left circumflex artery were detected). There was close agreement between magnetic resonance and x-ray angiography for the distance of the stenosis from the arterial origin (magnetic resonance mean (SD) 27 (16) mm versus x-ray angiography 27 (16) mm, P = NS, mean difference -0.2 mm). The distance to 39 stenoses (83%) agreed to within 5 mm, with increased scatter for more distal stenoses. The severity of magnetic resonance signal loss, assessed visually at the site of stenosis, varied significantly according to the percentage diameter stenosis (F = 30, P < 0.0001); stenosis severity with severe signal loss was 89 (7)%, with partial signal was 70 (16)%, and with irregular wall only 37 (11)%, with significant differences among the three groups (P < 0.001). A significant correlation was found between the proportional magnetic resonance signal loss at the stenosis and the percentage diameter stenosis severity (r = -0.67, P < 0.0001). The length of stenosis measured by magnetic resonance (6 (3) mm) was greater than by x-ray angiography (5 (2) mm, P < 0.006, mean difference +1.1 mm). Spearman's rank test showed that there was significant overestimation of stenosis length by magnetic resonance as stenosis severity increased (rs = 0.34, P < 0.02). CONCLUSIONS: Accurate localisation of coronary stenosis and a qualitative assessment of stenosis severity are possible by magnetic resonance, but stenosis length is overestimated as severity increases, probably because of disturbed patterns of flow with turbulence distal to severe stenoses. Reasonable results for the detection of coronary artery stenosis by magnetic resonance were achieved in this highly selected population, but further progress in imaging techniques is necessary before moving towards appreciable clinical application. Images PMID:8673749

Pennell, D. J.; Bogren, H. G.; Keegan, J.; Firmin, D. N.; Underwood, S. R.

1996-01-01

195

Instrumentation for parallel magnetic resonance imaging  

E-print Network

of simultaneous reception of up to sixty-four, 1 MHz bandwidth MR signals, at imaging frequencies from 63 to 200 MHz, with an SNR performance (on each channel) comparable to that of a single-channel commercial MR receiver. The prototype should enable investigation...

Brown, David Gerald

2007-04-25

196

PREAMPLIFYING CANTILEVERS FOR CONTACT RESONANCE MODE IMAGING  

E-print Network

applications are in the areas of ferroelectric domain imaging [1]-[5]. The amplification was demonstrated with measurements on ferroelectric materials- which included periodically poled lithium niobate (PPLN). Feasibility-5), either higher AC electric fields have to be applied or an actuation frequency close to the contact

197

5.4 Magnetic Resonance Imaging, Diagnostic Ultrasound  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume A 'Fundamentals and Data in Radiobiology, Radiation Biophysics, Dosimetry and Medical Radiological Protection' of Volume 7 'Medical Radiological Physics' of Landolt-Börnstein - Group VIII 'Advanced Materials and Technologies'. It contains the Section '5.4 Magnetic Resonance Imaging, Diagnostic Ultrasound' of the Chapter '5 Medical Radiological Protection' with the contents:

Bernhardt, J. H.

198

Magnetic resonance imaging (MRI) of inflammation in stroke  

Microsoft Academic Search

Magnetic resonance imaging (MRI) of inflammation is based on the in vivo magnetic labelling of macrophages, the most abundant cells involved in the post-ischemic inflammatory response, by nanoparticles of iron oxides. Such approach has been successfully applied to study experimental rodent models of focal cerebral ischemia and has proved feasible in pioneer clinical studies. Despite current limitations, MRI of inflammation

Marlène Wiart; Nathalie Davoust; Jean-Baptiste Pialat; Yves Berthezène; Norbert Nighoghossian

2007-01-01

199

Three-Dimensional Magnetic Resonance Imaging of Velopharyngeal Structures  

ERIC Educational Resources Information Center

Purpose: To report the feasibility of using a 3-dimensional (3D) magnetic resonance imaging (MRI) protocol for examining velopharyngeal structures. Using collected 3D MRI data, the authors investigated the effect of sex on the midsagittal velopharyngeal structures and the levator veli palatini (levator) muscle configurations. Method: Ten Caucasian…

Bae, Youkyung; Kuehn, David P.; Sutton, Bradley P.; Conway, Charles A.; Perry, Jamie L.

2011-01-01

200

Functional Connectivity Magnetic Resonance Imaging Classification of Autism  

ERIC Educational Resources Information Center

Group differences in resting state functional magnetic resonance imaging connectivity between individuals with autism and typically developing controls have been widely replicated for a small number of discrete brain regions, yet the whole-brain distribution of connectivity abnormalities in autism is not well characterized. It is also unclear…

Anderson, Jeffrey S.; Nielsen, Jared A.; Froehlich, Alyson L.; DuBray, Molly B.; Druzgal, T. Jason; Cariello, Annahir N.; Cooperrider, Jason R.; Zielinski, Brandon A.; Ravichandran, Caitlin; Fletcher, P. Thomas; Alexander, Andrew L.; Bigler, Erin D.; Lange, Nicholas; Lainhart, Janet E.

2011-01-01

201

Human Brain Language Areas Identified by Functional Magnetic Resonance Imaging  

Microsoft Academic Search

Functional magnetic resonance imaging (FMRI) was used to identify candidate language processing areas in the intact hu- man brain. Language was defined broadly to include both phonological and lexical-semantic functions and to exclude sensory, motor, and general executive functions. The language activation task required phonetic and semantic analysis of aurally presented words and was compared with a control task involving

Jeffrey R. Binder; Julie A. Frost; Thomas A. Hammeke; Robert W. Cox; Stephen M. Rao; Thomas Prieto

1997-01-01

202

Permutation Testing Made Practical for Functional Magnetic Resonance Image Analysis  

Microsoft Academic Search

We describe an efficient algorithm for the step-down permutation test, applied to the analysis of functional magnetic resonance images. The algorithm's time bound is nearly linear, making it feasible as an interactive tool. Results of the permutation test algorithm applied to data from a cognitive activation paradigm are compared with those of a standard parametric test corrected for multiple comparisons.

Matthew Belmonte; Deborah Yurgelun-todd

2001-01-01

203

Cognitive-Pharmacologic Functional Magnetic Resonance Imaging in Tourette Syndrome  

E-print Network

Cognitive-Pharmacologic Functional Magnetic Resonance Imaging in Tourette Syndrome: A Pilot Study and vocalizations (tics) in Tourette syndrome (TS); however, dopamine-responsive abnormal function in specific brain dopamine antagonists and agonists alleviate tics. Key Words: Tourette syndrome, physiopathology, dopamine

204

Blood Flow Magnetic Resonance Imaging of Retinal Degeneration  

E-print Network

Blood Flow Magnetic Resonance Imaging of Retinal Degeneration Yingxia Li,1 Haiying Cheng,1 Qiang. Duong1,2,3,4,5,6,7 PURPOSE. This study aims to investigate quantitative basal blood flow as well as hypercapnia- and hyperoxia-induced blood flow changes in the retinas of the Royal College of Surgeons (RCS

Duong, Timothy Q.

205

Toward Measuring Program Comprehension with Functional Magnetic Resonance Imaging  

E-print Network

. This way, we hope to relate program comprehension to other cognitive processes (e.g., reading comprehensionToward Measuring Program Comprehension with Functional Magnetic Resonance Imaging Janet Siegmund Program comprehension is an often evaluated, internal cog- nitive process. In neuroscience, functional

Kaestner, Christian

206

RECONSTRUCTION OF HUMAN LUNG MORPHOLOGY MODELS FROM MAGNETIC RESONANCE IMAGES  

EPA Science Inventory

Reconstruction of Human Lung Morphology Models from Magnetic Resonance Images T. B. Martonen (Experimental Toxicology Division, U.S. EPA, Research Triangle Park, NC 27709) and K. K. Isaacs (School of Public Health, University of North Carolina, Chapel Hill, NC 27514) ...

207

Detection of Prostate Cancer from Multiparametric Magnetic Resonance Imaging  

E-print Network

050 051 052 053 Detection of Prostate Cancer from Multiparametric Magnetic Resonance Imaging Anonymous (MRI) based technique of detecting prostate cancer is developed. A machine learning algorithm, based. The classifier is trained to detect prostate cancer in the peripheral zone and using the trained classifier

de Freitas, Nando

208

Antimyosin Scintigraphy Compared With Magnetic Resonance Imaging in Inflammatory Myopathies  

Microsoft Academic Search

Objective: To compare indium In 111 altumomab pen- tetate-labeled antimyosin scintigraphy with magnetic resonance imaging (MRI) in the diagnosis and fol- low-up of patients with myositis. Design and Methods: Sixteen patients with polymyo- sitis and 1 patient with dermatomyositis, all verified with biopsy samples, were examined during diagnostic evalu- ation with antimyosin antibody scintigraphy and low- field MRI of the

Mervi Lofberg; Kristian Liewendahl; Antti Lamminen; Ossi Korhola; Hannu Somer

1998-01-01

209

Original Research In Vivo Magnetic Resonance Imaging of the Human  

E-print Network

Original Research In Vivo Magnetic Resonance Imaging of the Human Cervical Spinal Cord at 3 Tesla is feasible at 3 T. Key Words: MRI; 3 Tesla; cervical spinal cord; gradient echo; gray matter; white matter J, and pulsatile flow (9,10). Deficits in motor and sensory function from damage to the spinal cord are mainly due

Gorassini, Monica

210

A Scalable Framework For Segmenting Magnetic Resonance Images  

PubMed Central

A fast, accurate and fully automatic method of segmenting magnetic resonance images of the human brain is introduced. The approach scales well allowing fast segmentations of fine resolution images. The approach is based on modifications of the soft clustering algorithm, fuzzy c-means, that enable it to scale to large data sets. Two types of modifications to create incremental versions of fuzzy c-means are discussed. They are much faster when compared to fuzzy c-means for medium to extremely large data sets because they work on successive subsets of the data. They are comparable in quality to application of fuzzy c-means to all of the data. The clustering algorithms coupled with inhomogeneity correction and smoothing are used to create a framework for automatically segmenting magnetic resonance images of the human brain. The framework is applied to a set of normal human brain volumes acquired from different magnetic resonance scanners using different head coils, acquisition parameters and field strengths. Results are compared to those from two widely used magnetic resonance image segmentation programs, Statistical Parametric Mapping and the FMRIB Software Library (FSL). The results are comparable to FSL while providing significant speed-up and better scalability to larger volumes of data. PMID:20046893

Hore, Prodip; Goldgof, Dmitry B.; Gu, Yuhua; Maudsley, Andrew A.; Darkazanli, Ammar

2009-01-01

211

Diagnosis of paraesophageal omental hiatal hernia by magnetic resonance imaging.  

PubMed

We present a case of an enlarging retrocardiac mass lesion in which we observed the magnetic resonance imaging (MRI) finding of a fatty tumor with contiguous blood vessels extending from the abdominal portion into the thoracic portion of the tumor. These surgically verified findings provide an MRI indication of the presence of a paraesophageal omental hiatal hernia. PMID:8417901

Rockoff, S D; Aaron, B L; Black, C; Kathuria, R; Biben, L

1993-01-01

212

Applications of nuclear magnetic resonance imaging in process engineering  

Microsoft Academic Search

During the past decade, the application of nuclear magnetic resonance (NMR) imaging techniques to problems of relevance to the process industries has been identified. The particular strengths of NMR techniques are their ability to distinguish between different chemical species and to yield information simultaneously on the structure, concentration distribution and flow processes occurring within a given process unit. In this

Lynn F. Gladden; Paul Alexander

1996-01-01

213

Gated magnetic resonance imaging of the normal and diseased heart  

SciTech Connect

Gated cardiac magnetic resonance (MR) images were obtained in two normal volunteers and 21 adults with a variety of cardiovascular abnormalities. The images were correlated with data from clinical examination, electrocardiograms, and cardiac catheterization. Gated cardiac images were superior to nongated images. Combined cardiac and respiratory gated images were superior to images obtained with cardiac gating only, but acquisition time was longer. Portions of the coronary arteries were visualized in seven of 23 examinations (30%), and subacute and old myocardial infarcts were seen in five of nine patients (55%) as areas of thinned myocardium. Normal cardiac anatomy (chambers, valves, and papillary muscles) was well visualized. Examples of aortic stenosis and atherosclerosis of the abdominal aorta are shown.

Lieberman, J.M.; Alfidi, R.J.; Nelson, A.D.; Botti, R.E.; Moir, T.W.; Haaga, J.R.; Kopiwoda, S.; Miraldi, F.D.; Cohen, A.M.; Butler, H.E.

1984-08-01

214

Magnetic Resonance Imaging Part I—Physical Principles  

PubMed Central

Magnetic resonance (MR) imaging is the most complex imaging technology available to clinicians. Whereas most imaging technologies depict differences in one, or occasionally two, tissue characteristics, MR imaging has five tissue variables—spin density, T1 and T2 relaxation times and flow and spectral shifts—from which to construct its images. These variables can be combined in various ways by selecting pulse sequences and pulse times to emphasize any desired combination of tissue characteristics in the image. This selection is determined by the user of the MR system before imaging data are collected. If the selection is not optimal, the imaging process must be repeated at a cost of time and resources. The optimal selection of MR imaging procedures and the proper interpretation of the resultant images require a thorough understanding of the basic principles of MR imaging. Included in this understanding should be at least the rudiments of how an MR imaging signal is produced and why it decays with time; the significance of relaxation constants; the principles of scanning methods such as saturation recovery, inversion recovery and spin echo; how data obtained by these methods are used to form an image, and how the imaging data are complied by multi-slice and volumetric processes. In selecting an MR imaging unit, information about different magnet designs (resistive, superconductive and permanent) is useful. Although no bioeffects are thought to be associated with an MR imaging examination, some knowledge of the attempts to identify bioeffects is helpful in alleviating concern in patients. Images PMID:6506686

Hendee, William R.; Morgan, Christopher J.

1984-01-01

215

Magnetic Resonance Imaging with Composite (Dual) Gradients  

PubMed Central

The tradeoff between gradient performance factors, size of the imaging region, and physiological factors such as nerve stimulation typically leads to compromises in gradient design and ultimately suboptimal imaging performance. Local gradient systems can add some performance flexibility, but are cumbersome to set up and remove. In nearly all conventional MRI systems, the use of local gradients precludes the use of the more homogeneous whole body gradients. This paper presents the concept of dynamically selectable composite gradient systems where local gradients and whole body gradients can be selected independently and simultaneously. The relative performance of whole body, insert, and composite gradients is predicted for echoplanar (EPI), turbo spin echo (TSE), and steady state free precession (SSFP). A realization of the concept is presented. PMID:20160925

Parker, Dennis L.; Goodrich, K. Craig; Hadley, J. Rock; Kim, Seong-Eun; Moon, Sung M.; Chronik, Blaine A.; Fontius, Ulrich; Schmitt, Franz

2009-01-01

216

Magnetic Resonance Imaging of the Prostate  

Microsoft Academic Search

The high incidence of prostate cancer, combined \\u000awith downstaging at diagnosis and the slow natural progression of the \\u000adisease, has made its management a complex and controversial issue. \\u000aEndorectal MRI is emerging as the most accurate imaging modality for \\u000athe local anatomic assessment of prostate cancer. This dissertation \\u000aassesses the value of current State-of-the-Art endorectal MRI in \\u000aclinical practice and

L. Wang

2007-01-01

217

Cardiac magnetic resonance imaging in children.  

PubMed

MRI is an important additional tool in the diagnostic work-up of children with congenital heart disease. This review aims to summarise the role MRI has in this patient population. Echocardiography remains the main diagnostic tool in congenital heart disease. In specific situations, MRI is used for anatomical imaging of congenital heart disease. This includes detailed assessment of intracardiac anatomy with 2-D and 3-D sequences. MRI is particularly useful for assessment of retrosternal structures in the heart and for imaging large vessel anatomy. Functional assessment includes assessment of ventricular function using 2-D cine techniques. Of particular interest in congenital heart disease is assessment of right and single ventricular function. Two-dimensional and newer 3-D techniques to quantify flow in these patients are or will soon become an integral part of quantification of shunt size, valve function and complex flow patterns in large vessels. More advanced uses of MRI include imaging of cardiovascular function during stress and tissue characterisation of the myocardium. Techniques used for this purpose need further validation before they can become part of the daily routine of MRI assessment of congenital heart disease. PMID:25552387

Helbing, Willem A; Ouhlous, Mohamed

2015-01-01

218

Ferromagnetic resonance imaging of Co films using magnetic resonance force microscopy  

SciTech Connect

Lateral one-dimensional imaging of cobalt (Co) films by means of microscopic ferromagnetic resonance (FMR) detected using the magnetic resonance force microscope (MRFM) is demonstrated. A novel approach involving scanning a localized magnetic probe is shown to enable FMR imaging in spite of the broad resonance linewidth. We introduce a spatially selective local field by means of a small, magnetically polarized spherical crystallite of yttrium iron garnet (YIG). Using MRFM-detected FMR signals from a sample consisting of two Co films, we can resolve the {approximately}20 {mu}m lateral separation between the films. The results can be qualitatively understood by consideration of the calculated spatial profiles of the magnetic field generated by the YIG sphere. {copyright} {ital 1998 American Vacuum Society.}

Suh, B.J.; Hammel, P.C.; Zhang, Z. [Condensed Matter and Thermal Physics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Condensed Matter and Thermal Physics, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Midzor, M.M.; Roukes, M.L. [Condensed Matter Physics, California Institute of Technology, Pasadena, California 91125 (United States)] [Condensed Matter Physics, California Institute of Technology, Pasadena, California 91125 (United States); Childress, J.R. [University of Florida, Gainesville, Florida 32611 (United States)] [University of Florida, Gainesville, Florida 32611 (United States)

1998-07-01

219

Fractal dimension of cerebral surfaces using magnetic resonance images  

SciTech Connect

The calculation of the fractal dimension of the surface bounded by the grey matter in the normal human brain using axial, sagittal, and coronal cross-sectional magnetic resonance (MR) images is presented. The fractal dimension in this case is a measure of the convolutedness of this cerebral surface. It is proposed that the fractal dimension, a feature that may be extracted from MR images, may potentially be used for image analysis, quantitative tissue characterization, and as a feature to monitor and identify cerebral abnormalities and developmental changes.

Majumdar, S.; Prasad, R.R.

1988-11-01

220

Magnetic resonance imaging of traumatic brain injury: a pictorial review.  

PubMed

Traumatic brain injury (TBI) is a significant source of major morbidity and mortality in blunt trauma patients. Computed tomography (CT) is the primary imaging modality of choice for patients with potential brain injury in the acute setting, with magnetic resonance imaging (MRI) playing a role in evaluating equivocal CT findings and may help with determining long-term prognosis and recovery. MRI is being utilized more commonly in the acute and subacute setting of TBI; therefore, radiologists should be familiar with the MRI appearance of the various manifestations of TBI. Here, we review the imaging of common intracranial injuries with illustrative cases comparing CT and MRI. PMID:25027313

Aquino, Christopher; Woolen, Sean; Steenburg, Scott D

2015-02-01

221

Interactions between magnetic resonance imaging and dental material  

PubMed Central

Magnetic resonance imaging (MRI) has become a common and important life-saving diagnostic tool in recent times, for diseases of the head and neck region. Dentists should be aware of the interactions of various restorative dental materials and different technical factors put to use by an MRI scanning machine. Specific knowledge about these impacts, at the dentist level and at the level of the personnel at the MRI centers can save valuable time for the patient and prevent errors in MRI images. Artifacts from metal restorations are a major hindrance at such times, as they result in disappearance or distortion of the image and loss of important information. PMID:23946562

Mathew, Chalakuzhiyl Abraham; Maller, Sudhakara; Maheshwaran

2013-01-01

222

Real-time Magnetic Resonance Imaging Guidance for Cardiovascular Procedures  

PubMed Central

Magnetic resonance imaging (MRI) of the cardiovascular system has proven to be an invaluable diagnostic tool. Given the ability to allow for real-time imaging, MRI guidance of intraoperative procedures can provide superb visualization which can facilitate a variety of interventions and minimize the trauma of the operations as well. In addition to the anatomic detail, MRI can provide intraoperative assessment of organ and device function. Instruments and devices can be marked to enhance visualization and tracking. All of which is an advance over standard x-ray or ultrasonic imaging. PMID:18395633

Horvath, Keith A.; Li, Ming; Mazilu, Dumitru; Guttman, Michael A.; McVeigh, Elliot R.

2008-01-01

223

Magnetic Field Gradient Calibration as an Experiment to Illustrate Magnetic Resonance Imaging  

ERIC Educational Resources Information Center

A nuclear magnetic resonance (NMR) spectroscopy experiment for the undergraduate physical chemistry laboratory is described that encompasses both qualitative and quantitative pedagogical goals. Qualitatively, the experiment illustrates how images are obtained in magnetic resonance imaging (MRI). Quantitatively, students experience the…

Seedhouse, Steven J.; Hoffmann, Markus M.

2008-01-01

224

Magnetic resonance imaging for image-guided implantology  

NASA Astrophysics Data System (ADS)

Image guided implantology using navigation systems is more accurate than manual dental implant insertion. The underlying image data are usually derived from computer tomography. The suitability of MR imaging for dental implant planning is a marginal issue so far. MRI data from cadaver heads were acquired using various MRI sequences. The data were assessed for the quality of anatomical imaging, geometric accuracy and susceptibility to dental metal artefacts. For dental implant planning, 3D models of the jaws were created. A software system for segmentation of the mandible and maxilla MRI data was implemented using c++, mitk, and qt. With the VIBE_15 sequence, image data with high geometric accuracy were acquired. Dental metal artefacts were lower than in CT data of the same heads. The segmentation of the jaws was feasible, in contrast to the segmentation of the dentition, since there is a lack of contrast to the intraoral soft tissue structures. MRI is a suitable method for imaging of the region of mouth and jaws. The geometric accuracy is excellent and the susceptibility to artefacts is low. However, there are yet two limitations: Firstly, the imaging of the dentition needs further improvement to allow accurate segmentation of these regions. Secondly, the sequence used in this study takes several minutes and hence is susceptible to motion artefacts.

Eggers, Georg; Kress, Bodo; Fiebach, Jochen; Rieker, Marcus; Spitzenberg, Doreen; Marmulla, Rüdiger; Dickhaus, Hartmut; Mühling, Joachim

2006-03-01

225

Algebraic reconstruction for magnetic resonance imaging under B0 inhomogeneity.  

PubMed

In magnetic resonance imaging, spatial localization is usually achieved using Fourier encoding which is realized by applying a magnetic field gradient along the dimension of interest to create a linear correspondence between the resonance frequency and spatial location following the Larmor equation. In the presence of B0 inhomogeneities along this dimension, the linear mapping does not hold and spatial distortions arise in the acquired images. In this paper, the problem of image reconstruction under an inhomogeneous field is formulated as an inverse problem of a linear Fredholm equation of the first kind. The operators in these problems are estimated using field mapping and the k-space trajectory of the imaging sequence. Since such inverse problems are known to be ill-posed in general, robust solvers, singular value decomposition and conjugate gradient method, are employed to obtain corrected images that are optimal in the Frobenius norm sense. Based on this formulation, the choice of the imaging sequence for well-conditioned matrix operators is discussed, and it is shown that nonlinear k-space trajectories provide better results. The reconstruction technique is applied to sequences where the distortion is more severe along one of the image dimensions and the two-dimensional reconstruction problem becomes equivalent to a set of independent one-dimensional problems. Experimental results demonstrate the performance and stability of the algebraic reconstruction methods. PMID:9735900

Kadah, Y M; Hu, X

1998-06-01

226

Cross-Validation of Deformable Registration With Field Maps in Functional Magnetic Resonance Brain Imaging  

Microsoft Academic Search

The localization of brain functional activity with respect to brain anatomy requires registration between a functional image and a reference high-resolution anatomical image. The fast functional magnetic resonance brain images acquired via echo planar imaging (EPI) in functional magnetic resonance imaging (fMRI) suffer from local geometric distortions. After performing standard rigid or affine registration, local nonlinear distortions of up to

Ali Gholipour; Nasser Kehtarnavaz; Kaundinya Gopinath; Richard Briggs

2008-01-01

227

Magnetic resonance images of neuronal migration anomalies.  

PubMed

Neuronal migration anomalies are a spectrum of brain malformations caused by insults to migrating neuroblasts during the sixth week to fifth month of gestation. To study the characteristics of MRI findings in migration anomalies, MR images of 36 patients (28 children and 8 adults) with migration anomalies were evaluated. Five patients had lissencephaly, eight had pachygyria, twelve had schizencephaly, six had heterotopias of gray matter, three had hemimegalencephaly, and two had polymicrogyria. The frequency of migration anomalies was 0.51% of all cranial MRI studies and 1.21% of pediatric cranial MRI studies at our hospital. The major clinical presentations of these patients were seizure (64%), development delay (42%), motor deficits (42%) and mental retardation (25%). Twenty-five patients (69%) associated with other brain anomalies, including: other migration anomalies in 12 cases (33%), absence of the septum pellucidum in 10 cases (28%), Dandy-Walker malformation/variant in 5 cases, arachnoid cyst in 4 cases, agenesis of the corpus callosum in 3 cases, holoprosencephaly in 2 cases, mega cisterna magna in 1 case and cephalocele in 1 case. Some of them presented with multiple complicated anomalies. As MR imaging provides superb gray-white matter distinction, details of cortical anatomy and multiplanar capability, it can clearly delineate the detail morphologic changes of the brain caused by neuronal migration disorders as well as the associated anomalies. PMID:9780601

Jaw, T S; Sheu, R S; Liu, G C; Chou, M S

1998-08-01

228

SEVEN TOPICS IN FUNCTIONAL MAGNETIC RESONANCE IMAGING  

PubMed Central

Functional MRI (fMRI) is a non-invasive brain imaging methodology that started in 1991 and allows human brain activation to be imaged at high resolution within only a few minutes. Because it has extremely high sensitivity, is relatively easy to implement, and can be performed on most standard clinical MRI scanners. It continues to grow at an explosive rate throughout the world. Over the years, at any given time, fMRI has been defined by only a handful of major topics that have been the focus of researchers using and developing the methodology. In this review, I attempt to take a snapshot of the field of fMRI as it is in mid-2009 by discussing the seven topics that I feel are most on the minds of fMRI researchers. The topics are, in no particular order or grouping: (1) Clinical impact, (2) Utilization of individual functional maps, (3) fMRI signal interpretation, (4) Pattern effect mapping and decoding, (5) Endogenous oscillations, (6) MRI technology, and (7) Alternative functional contrast mechanisms. Most of these topics are highly interdependent, each advancing as the others advance. While most fMRI involves applications towards clinical or neuroscience questions, all applications are fundamentally dependent on advances in basic methodology as well as advances in our understanding of the relationship between neuronal activity and fMRI signal changes. This review neglects almost completely an in-depth discussion of applications. Rather the discussions are on the methods and interpretation. PMID:19938211

BANDETTINI, PETER A.

2010-01-01

229

Use of i-gel in magnetic resonance imaging.  

PubMed

Anesthesia for magnetic resonance imaging (MRI) requires special equipment that can be used in the presence of a magnetic field. Endotracheal tube and various laryngeal mask airway devices have a variable quantity of ferromagnetic material in the pilot balloon that could reduce image quality and result in artifacts. The i-gel is a reliable, easily inserted airway device, and causes minimal interference in image quality. We used i-gel in 10 anaesthetized adult patients undergoing MRI. The quality of image, evidence of airway, tongue, and dental trauma were assessed throughout the procedure. All scans were diagnostically adequate. Therefore, we concluded that i-gel causes the least ferromagnetic interference compared with other devices and improves the quality of imaging and produces minimal artifact while scanning. PMID:24999218

Kaur, Kiranpreet; Bhardwaj, Mamta; Kumar, Prashant; Lal, Jatin; Johar, Sanjay; Hooda, Sarla

2014-03-01

230

Long-lived localization in magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

The longitudinal nuclear relaxation time, T1, sets a stringent limit on the range of information that can be obtained from magnetic resonance imaging (MRI) experiments. Long-lived nuclear spin states provide a possibility to extend the timescale over which information can be encoded in magnetic resonance. We introduce a strategy to localize an ensemble of molecules for a significantly extended duration (?30 times longer than T1 in this example), using a spatially selective conversion between magnetization and long-lived singlet order. An application to tagging and transport is proposed.

Dumez, Jean-Nicolas; Hill-Cousins, Joseph T.; Brown, Richard C. D.; Pileio, Giuseppe

2014-09-01

231

Detection of Light Images by Simple Tissues as Visualized by Photosensitized Magnetic Resonance Imaging  

Microsoft Academic Search

In this study, we show how light can be absorbed by the body of a living rat due to an injected pigment circulating in the blood stream. This process is then physiologically translated in the tissue into a chemical signature that can be perceived as an image by magnetic resonance imaging (MRI). We previously reported that illumination of an injected

Catherine Tempel-Brami; Iddo Pinkas; Avigdor Scherz; Yoram Salomon; Timothy Secomb

2007-01-01

232

Regression Models for Identifying Noise Sources in Magnetic Resonance Images  

PubMed Central

Stochastic noise, susceptibility artifacts, magnetic field and radiofrequency inhomogeneities, and other noise components in magnetic resonance images (MRIs) can introduce serious bias into any measurements made with those images. We formally introduce three regression models including a Rician regression model and two associated normal models to characterize stochastic noise in various magnetic resonance imaging modalities, including diffusion-weighted imaging (DWI) and functional MRI (fMRI). Estimation algorithms are introduced to maximize the likelihood function of the three regression models. We also develop a diagnostic procedure for systematically exploring MR images to identify noise components other than simple stochastic noise, and to detect discrepancies between the fitted regression models and MRI data. The diagnostic procedure includes goodness-of-fit statistics, measures of influence, and tools for graphical display. The goodness-of-fit statistics can assess the key assumptions of the three regression models, whereas measures of influence can isolate outliers caused by certain noise components, including motion artifacts. The tools for graphical display permit graphical visualization of the values for the goodness-of-fit statistic and influence measures. Finally, we conduct simulation studies to evaluate performance of these methods, and we analyze a real dataset to illustrate how our diagnostic procedure localizes subtle image artifacts by detecting intravoxel variability that is not captured by the regression models. PMID:19890478

Zhu, Hongtu; Li, Yimei; Ibrahim, Joseph G.; Shi, Xiaoyan; An, Hongyu; Chen, Yashen; Gao, Wei; Lin, Weili; Rowe, Daniel B.; Peterson, Bradley S.

2009-01-01

233

Elastomeric actuator devices for magnetic resonance imaging  

NASA Technical Reports Server (NTRS)

The present invention is directed to devices and systems used in magnetic imaging environments that include an actuator device having an elastomeric dielectric film with at least two electrodes, and a frame attached to the actuator device. The frame can have a plurality of configurations including, such as, for example, at least two members that can be, but not limited to, curved beams, rods, plates, or parallel beams. These rigid members can be coupled to flexible members such as, for example, links wherein the frame provides an elastic restoring force. The frame preferably provides a linear actuation force characteristic over a displacement range. The linear actuation force characteristic is defined as .+-.20% and preferably 10% over a displacement range. The actuator further includes a passive element disposed between the flexible members to tune a stiffness characteristic of the actuator. The passive element can be a bi-stable element. The preferred embodiment actuator includes one or more layers of the elastomeric film integrated into the frame. The elastomeric film can be made of many elastomeric materials such as, for example, but not limited to, acrylic, silicone and latex.

Dubowsky, Steven (Inventor); Hafez, Moustapha (Inventor); Jolesz, Ferenc A. (Inventor); Kacher, Daniel F. (Inventor); Lichter, Matthew (Inventor); Weiss, Peter (Inventor); Wingert, Andreas (Inventor)

2008-01-01

234

Clinical examination or whole-body magnetic resonance imaging: the Holy Grail of spondyloarthritis imaging  

PubMed Central

Whole-body magnetic resonance imaging allows acquisition of diagnostic images in the shortest scan time, leading to better patient compliance and artifact-free images. Methods of clinical examination of the anterior chest wall joints vary between physician groups and consideration of the rules of rib motion is suggested. The type of joint and its synovial lining may also aid imaging/clinical correlation. This well-written study by experts in the field with a standardized design and methodology allows good scientific analysis and suggests the advantages of whole-body magnetic resonance imaging in anterior chest wall imaging. Selection of clinical examination criteria and specific joints may have had an influence on the study results and the lack of association reported. PMID:22380535

2012-01-01

235

Application of Parallel Imaging to Murine Magnetic Resonance Imaging  

E-print Network

feed of this "dual-plane pair" element also eliminates the need for baluns in this case. The use of the element design in a 10-channel adjustable array coil for mouse imaging is presented, styled as a human cardiac top-bottom half-rack design...

Chang, Chieh-Wei 1980-

2012-09-21

236

Improved Guided Image Fusion for Magnetic Resonance and Computed Tomography Imaging  

PubMed Central

Improved guided image fusion for magnetic resonance and computed tomography imaging is proposed. Existing guided filtering scheme uses Gaussian filter and two-level weight maps due to which the scheme has limited performance for images having noise. Different modifications in filter (based on linear minimum mean square error estimator) and weight maps (with different levels) are proposed to overcome these limitations. Simulation results based on visual and quantitative analysis show the significance of proposed scheme. PMID:24695586

Jameel, Amina

2014-01-01

237

Computed tomography and magnetic resonance imaging comparisons in boxers  

SciTech Connect

The efficacy of computed tomography (CT) and magnetic resonance imaging (MRI) in identifying traumatic injuries of the brain was compared in a referred population of 21 amateur and professional boxers. Three boxers displayed CT scans with equivocal findings that were verified as artifacts by MRI. Eleven boxers had both CT and MRI scans with normal findings, and 7 boxers had both CT and MRI scans with abnormal findings. There were no instances where abnormalities demonstrated on CT scanning were not detected by MRI. However, some abnormalities detected on MRI were not detected on CT scans. These included a subdural hematoma, white-matter changes, and a focal contusion. Magnetic resonance imaging appears to be the neuroradiodiagnostic test of choice compared with CT.

Jordan, B.D. (Hospital for Special Surgery, New York, NY (USA)); Zimmerman, R.D. (New York Hospital-Cornell Medical Center, NY (USA))

1990-03-23

238

Magnetic resonance image-guided biopsy and aspiration.  

PubMed

Recent advances in magnet design and magnetic resonance (MR) system technology coupled with the development of fast gradient-echo pulse sequences have contributed to the increasing interest in interventional magnetic resonance imaging (MRI). Minimally invasive diagnostic and therapeutic image-based intervention can now be performed under near real-time MR guidance, taking advantage of the high tissue contrast, spatial resolution, vascular conspicuity and multiplanar capabilities of MRI to achieve safe and precise needle placement. This is particularly advantageous for needle navigation in regions of complex anatomy, such as the suprahyoid neck. This article discusses the theoretical concepts and clinical applications of MR for guidance for biopsy and aspiration, and highlights the technical developments that provide the foundation for interventional MRI. PMID:11145209

Lewin, J S; Nour, S G; Duerk, J L

2000-06-01

239

Planar Magnetic Metamaterial Slabs for Magnetic Resonance Imaging Applications  

NASA Astrophysics Data System (ADS)

A type of planar magnetic metamaterial is proposed with a square winding microstructure as a superlens for magnetic resonance imaging (MRI) applications. A direct magnetic field mapping measurement demonstrates that the radio-frequency magnetic field passing through the superlens is increased by as high as 46.9% at the position of about 3 cm behind the superlens. The resonance frequency of the fabricated slabs is found to be in good agreement with the target frequency (63.6 MHz) for a 1.5T MRI system. MRI experiments with the magnetic superlens show that the intensity of the image and the SNR (signal-to-noise ratio) are both enhanced, implying promising MRI applications of our planar magnetic superlens.

Li, Chun-Lai; Guo, Jie; Zhang, Peng; Yu, Quan-Qiang; Ma, Wei-Tao; Miao, Xi-Gen; Zhao, Zhi-Ya; Luan, Lin

2014-07-01

240

Functionalized 129Xe contrast agents for magnetic resonance imaging  

PubMed Central

The concept of ‘xenon biosensor’ for magnetic resonance imaging (MRI) was first proposed by a Berkeley team in 2001, with evidence that hyperpolarized 129Xe bound to a biotin-labeled cryptophane can detect streptavidin at much lower concentrations (nM-?M) than is typical for contrast-enhanced MRI experiments. 129Xe biosensors have undergone many recent developments to address challenges in molecular imaging. For example, cryptophanes have been synthesized that exhibit 10-fold higher xenon affinity with distinct 129Xe magnetic resonance spectra. Also relevant are dendrimeric cryptophane assemblies and inorganic zeolites that localize many 129Xe atoms to rare targets. Finally, this article considers biosensors that produce measurable changes in 129Xe chemical shift based upon the activity of oligonucleotides, proteins, or enzymes, and includes the first cell studies. PMID:19914122

Taratula, Olena; Dmochowski, Ivan J.

2009-01-01

241

Magnetic resonance imaging findings of spinal intramedullary spirocercosis.  

PubMed

Spirocerca lupi is a nematode infecting dogs in tropical and subtropical areas. Aberrant S. lupi migration to different body organs, including the spinal cord, has been documented. To date, the diagnosis of aberrant spinal cord migration was made at post-mortem examination or as an incidental finding, during spinal surgery. We describe two dogs with acute asymmetric paraparesis that were subsequently diagnosed with spinal cord spirocercosis. In magnetic resonance (MR) images of the spine, T2 hyperintense lesions were seen in the spinal cord of both dogs. The lesions appeared isointense on T1-weighted images and focal enhancement was detected after gadolinium administration. The MR imaging findings were compatible with focal inflammation, presumably along the parasite migration tract. Gross and microscopic pathologic findings confirmed the diagnosis of aberrant spinal intramedullary migration of S. lupi in one dog, and in the other dog, the clinical and imaging findings were supportive of this diagnosis. PMID:18833954

Chai, Orit; Shelef, Ilan; Brenner, Ori; Dogadkin, Osnat; Aroch, Itamar; Shamir, Merav H

2008-01-01

242

The Australian magnetic resonance imaging-linac program.  

PubMed

The Australian magnetic resonance imaging (MRI)-Linac program is a $16-million government-funded project to advance the science and clinical practice of exquisite real-time anatomical and physiological adaptive cancer therapy. The centerpiece of the program is a specifically designed 1-T open-bore MRI/6-MV linac system that is planned for delivery and completion of installation in 2014. Current scientific endeavors include engineering discovery in MRI component design, quantifying MRI and linac interactions, and developing image guidance and adaptation strategies. PMID:24931094

Keall, Paul J; Barton, Michael; Crozier, Stuart

2014-07-01

243

MRI (Magnetic Resonance Imaging) : tour an MRI machine  

NSDL National Science Digital Library

In this resource, appropriate for students in high school and beyond, the user navigates through a five-page illustrated explanation of MRI (magnetic resonance imaging). Each page profiles a different step in the MRI process. The resource addresses the science behind how MRI works, revealing how a strong magnet and radio wave pulses affect the targeted area of the body and allow that area to be imaged. As part of a set of materials about brain scanning technologies, this resource focuses on brain MRI. Copyright 2005 Eisenhower National Clearinghouse

David Grubin Productions

2001-01-01

244

Magnetic resonance imaging of gel-cast ceramic composites  

SciTech Connect

Magnetic resonance imaging (MRI) techniques are being employed to aid in the development of advanced near-net-shape gel-cast ceramic composites. MRI is a unique nondestructive evaluation tool that provides information on both the chemical and physical properties of materials. In this effort, MRI imaging was performed to monitor the drying of porous green-state alumina - methacrylamide-N.N`-methylene bisacrylamide (MAM-MBAM) polymerized composite specimens. Studies were performed on several specimens as a function of humidity and time. The mass and shrinkage of the specimens were also monitored and correlated with the water content.

Dieckman, S.L.; Balss, K.M.; Waterfield, L.G. [and others

1997-04-01

245

Magnetic resonance imaging for the ophthalmologist: A primer  

PubMed Central

Magnetic resonance imaging (MRI) and computerized tomography (CT) have added a new dimension in the diagnosis and management of ocular and orbital diseases. Although CT is more widely used, MRI is the modality of choice in select conditions and can be complimentary to CT in certain situations. The diagnostic yield is best when the ophthalmologist and radiologist work together. Ophthalmologists should be able to interpret these complex imaging modalities as better clinical correlation is then possible. In this article, we attempt to describe the basic principles of MRI and its interpretation, avoiding confusing technical terms. PMID:22824600

Simha, Arathi; Irodi, Aparna; David, Sarada

2012-01-01

246

Bulk and surface sensitivity of a resonant waveguide grating imager  

NASA Astrophysics Data System (ADS)

We report the assessment of the sensitivity of a microplate-compatible resonant waveguide grating imager. The sensitivity to bulk refractive index changes was determined using a serial dilution of glycerol solution with the help of a refractometer. The surface sensitivity was examined using layer-by-layer polyelectrolyte films in conjunction with optical waveguide lightmode spectroscopy and characterized by the binding of acetazolamide to immobilized carbonic anhydrase under microfluidics. The results suggest that the imager has a limit of detection down to 2.2 × 10-6 for refractive index change and 0.078 ng/cm2 for the adsorbed mass.

Orgovan, Norbert; Kovacs, Boglarka; Farkas, Eniko; Szabó, Bálint; Zaytseva, Natalya; Fang, Ye; Horvath, Robert

2014-02-01

247

Computed tomography and magnetic resonance images of adrenocortical oncocytoma cases.  

PubMed

We present two cases of adrenocortical oncocytomas that were well-delineated on multi-detector computed tomography and magnetic resonance imaging. The images showed a well-enhanced large mass with multiple stippled calcifications in a 10-yr-old girl who was consulted due to precocious puberty. A well-enhanced solid mass with necrotic components was incidentally noticed in a 54-yr-old man. These lesions were resected and diagnosed as adrenocortical oncocytomas through immunohistochemical studies and electron microscopy. Adrenocortical oncocytomas are rare disease entities, therefore, we report these interesting, rare adrenocortical oncocytomas here with radiologic findings, and discuss differential diagnosis. PMID:24616598

Yoon, Jung-Hee; Cha, Seong-Sook; Yoon, Seong Kuk

2014-03-01

248

A practical guide to nonvascular thoracic magnetic resonance imaging.  

PubMed

There is increasing perception that thoracic magnetic resonance imaging (MRI) is underutilized. Various obstacles to implementation and utilization of thoracic MRI can be overcome with continuous updating, improvement, and standardization of thoracic MRI protocols, close collaboration with MRI technologists, continued education of MRI technologists, radiologists, and referring health care providers, and incorporation of MRI training into thoracic imaging fellowship programs. The purpose of this article is to share the author's experience in developing a successful nonvascular thoracic MRI practice, discuss the fundamentals of nonvascular thoracic MRI, and provide a "how-to" manual for its performance. PMID:24361974

Ackman, Jeanne B

2014-01-01

249

Spinal cord magnetic resonance imaging in suspected multiple sclerosis  

Microsoft Academic Search

.   We examined the value of spinal cord magnetic resonance imaging (MRI) in the diagnostic work-up of multiple sclerosis (MS).\\u000a Forty patients suspected of having MS were examined within 24 months after the start of symptoms. Disability was assessed,\\u000a and symptoms were categorized as either brain or spinal cord. Work-up further included cerebrospinal fluid analysis and standard\\u000a proton-density, T2-, and

G. J. Lycklama à Nijeholt; B. M. J. Uitdehaag; E. Bergers; J. A. Castelijns; C. H. Polman; F. Barkhof

2000-01-01

250

Molecular magnetic resonance imaging with targeted contrast agents  

Microsoft Academic Search

Magnetic resonance imaging (MRI) produces high-resolution three-dimensional maps delineating morphological features of the specimen. Differential contrast in soft tissues depends on endogenous differences in water content, relaxation times, and\\/or diffusion characteristics of the tissue of interest. The specificity of MRI can be further increasedbyexogenouscontrastagents(CA)suchasgadoliniumchelates,whichhavebeensuccessfullyusedforimaging of hemodynamic parameters including blood perfusion and vascular permeability. Development of targeted MR CA directed to

Dmitri Artemov

2003-01-01

251

Magnetic Resonance Imaging of Stroke in the Rat  

PubMed Central

Magnetic resonance imaging (MRI) is now a routine neuroimaging tool in the clinic. Throughout all phases of stroke from acute to chronic, MRI plays an important role to diagnose, evaluate and monitor the cerebral tissue undergoing stroke. This review provides a description of various MRI methods and an overview of selected MRI studies, with an embolic stroke model of rat, performed in the MRI laboratory of Department of Neurology, Henry Ford Hospital, Detroit, Michigan, US. PMID:24920874

CHOPP, Michael; LI, Lian; ZHANG, Li; ZHANG, Zheng-gang; LI, Qing-jiang; JIANG, Quan

2014-01-01

252

Nuclear magnetic resonance imaging of water motion in plants  

Microsoft Academic Search

This Thesis treats one of the new techniques in plant science i.e. nuclear magnetic resonance imaging (NMRi) applied to water motion in plants. It is a challenge, however, to measure this motion in intact plants quantitatively, because plants impose specific problems when studied using NMRi. At high magnetic field strength air-filled intercellular spaces in the plant tissue cause susceptibility-related local

T. W. J. Scheenen

2001-01-01

253

Magnetic Resonance Imaging of Benign Cardiac Masses: A Pictorial Essay  

PubMed Central

The differential diagnosis for a cardiac mass includes primary and metastatic neoplasms. While primary cardiac tumors are rare, metastatic disease to the heart is a common finding in cancer patients. Several “tumor-like” processes can mimic a true cardiac neoplasm with accurate diagnosis critical at guiding appropriate management. We present a pictorial essay of the most common benign cardiac masses and “mass-like” lesions with an emphasis on magnetic resonance imaging features. PMID:24083071

Ward, Thomas J.; Kadoch, Michael A.; Jacobi, Adam H.; Lopez, Pablo P.; Salvo, Javier Sanz; Cham, Matthew D.

2013-01-01

254

Experiences with functional magnetic resonance imaging at 1 tesla  

Microsoft Academic Search

Functional magnetic resonance imaging (fMRI) has been performed on a standard 1 T system using a pulse sequence developed to utilize blood oxygen level dependent (BOLD) contrast and an oV-line analysis routine using correlation techniques. The sequence and the data analysis routine have been validated by reproducing the conventional hand movement paradigm studies reported by numerous other workers. Our work

A P JONES; D G HUGHES; D S BRETTLE; L ROBINSON; J R SYKES; Q AZIZ; S HAMDY; D G THOMPSON; S W G DERBYSHIRE; A C N CHEN

1998-01-01

255

Magnetic resonance imaging of the normal bone marrow  

Microsoft Academic Search

The bone marrow is a complex organ that contains fat and nonfat cells, the proportions of which vary greatly with age and\\u000a in the different bones of the skeleton. Magnetic resonance (MR) imaging provides information on the composition of the medullary\\u000a cavity of any given bone and on the distribution of red and yellow marrow in the skeleton. This article

Bruno C. Vande Berg; Jacques Malghem; Frederic E. Lecouvet; Baudouin Maldague

1998-01-01

256

Dynamic molecular imaging using nanoparticle plasmon resonance coupling  

NASA Astrophysics Data System (ADS)

Distance dependant coupling of plasmon resonances between closely spaced metal nanoparticles offers an attractive alternative for the imaging of molecular interactions. Here we analyzed interactions between molecular specific gold nanoparticles and live cells using a combination of dark-field reflectance and hyperspectral imaging. The results of optical imaging were correlated with transmittance electron microscopy of cell slices and theoretical simulations of optical properties of gold aggregates. We showed that nanoparticles targeted to epidermal growth factor receptor (EGFR) form closely spaced assemblies in the presence of the target molecule. Our experiments with living cells showed that receptor mediated assembly and plasmon coupling of gold bioconjugates result in a spectral shift of more than 100 nm in plasmon resonance frequency of the nanoparticles giving a very bright red signal. We demonstrated that plasmon coupling can be used for imaging of EGFR activation and trafficking as formation of EGFR dimers and further intracellular uptake in early and late endosomes is associated with progressive color changes from green to red, respectively, with each stage of EGFR cycle being associated with a distinct color of EGFR bound nanoparticles. This approach can allow imaging of molecular interactions ranging from protein pairs to multi-protein complexes with sensitivity and SNR that cannot be currently achieved with any other method.

Sokolov, K.; Aaron, J.; Larson, T.; Travis, K.; Harrison, N.

2010-02-01

257

Calibration of a resonance energy transfer imaging system.  

PubMed Central

A quantitative technique for the nondestructive visualization of nanometer scale intermolecular separations in a living system is described. A calibration procedure for the acquisition and analysis of resonance energy transfer (RET) image data is outlined. The factors limiting RET imaging of biological samples are discussed. Measurements required for the calibration include: (a) the spectral sensitivity of the image intensifier (or camera); (b) the transmission spectra of the emission filters; and (c) the quantum distribution functions of the energy transfer pair measured in situ. Resonance energy transfer imaging is demonstrated for two DNA specific dyes. The Förster critical distance for energy transfer between Hoechst 33342 (HO) and acridine orange (AO) is 4.5 +/- 0.7 nm. This distance is slightly greater than the distance of a single turn of the DNA helix (3.5 nm or approximately 10 base pairs), and is well below the optical diffraction limit. Timed sequences of intracellular energy transfer reveal nuclear structure, strikingly similar to that observed with confocal and electron microscopy, and may show the spatial distribution of eu- and hetero- chromatin in the interphase nuclei. Images FIGURE 6 PMID:1581499

Ludwig, M; Hensel, N F; Hartzman, R J

1992-01-01

258

Microtesla magnetic resonance imaging with a superconducting quantum interference device  

SciTech Connect

We have constructed a magnetic resonance imaging (MRI) scanner based on a dc Superconducting QUantum Interference Device (SQUID) configured as a second-derivative gradiometer. The magnetic field sensitivity of the detector is independent of frequency; it is therefore possible to obtain high-resolution images by prepolarizing the nuclear spins in a field of 300 mT and detecting the signal at 132 fYT, corresponding to a proton Larmor frequency of 5.6 kHz. The reduction in the measurement field by a factor of 10,000 compared with conventional scanners eliminates inhomogeneous broadening of the nuclear magnetic resonance lines, even in fields with relatively poor homogeneity. The narrow linewidths result in enhanced signal-to-noise ratio and spatial resolution for a fixed strength of the magnetic field gradients used to encode the image. We present two-dimensional images of phantoms and pepper slices, obtained in typical magnetic field gradients of 100 fYT/m, with a spatial resolution of about 1mm. We further demonstrate a slice-selected image of an intact pepper. By varying the time delay between removal of the polarizing field and initiation of the spin echo sequence we acquire T1-weighted contrast images of water phantoms, some of which are doped with a paramagnetic salt; here, T1 is the nuclear spin-lattice relaxation time. The techniques presented here could readily be adapted to existing multichannel SQUID systems used for magnetic source imaging of brain signals. Further potential applications include low-cost systems for tumor screening and imaging peripheral regions of the body.

McDermott, Robert; Lee, SeungKyun; ten Haken, Bennie; Trabesinger, Andreas H.; Pines, Alexander; Clarke, John

2004-03-15

259

Spectrally Resolved Magnetic Resonance Imaging of the XenonBiosensor  

SciTech Connect

Due to its ability to non-invasively record images, as well as elucidate molecular structure, nuclear magnetic resonance is the method of choice for applications as widespread as chemical analysis and medical diagnostics. Its detection threshold is, however, limited by the small polarization of nuclear spins in even the highest available magnetic fields. This limitation can, under certain circumstances, be alleviated by using hyper-polarized substances. Xenon biosensors make use of the sensitivity gain of hyperpolarized xenon to provide magnetic resonance detection capability for a specific low-concentration target. They consist of a cryptophane cage, which binds one xenon atom, and which has been connected via a linker to a targeting moiety such as a ligand or antibody. Recent work has shown the possibility of using the xenon biosensor to detect small amounts of a substance in a heterogeneous environment by NMR. Here, we demonstrate that magnetic resonance (MR) provides the capability to obtain spectrally and spatially resolved images of the distribution of immobilized biosensor, opening the possibility for using the xenon biosensor for targeted imaging.

Hilty, Christian; Lowery, Thomas; Wemmer, David; Pines, Alexander

2005-07-15

260

Magnetic resonance imaging of the lumbar herniated disc in pregnancy.  

PubMed

Lumbosacral pain is a significant complaint in approximately one-half of all pregnancies. In 15%, the pain can be disabling. Although the mechanical and positional stresses of pregnancy have been cited as the primary source of this discomfort, in approximately 1:10,000 cases a herniated lumbar disc (HNP) can be identified as the proximal cause of pain. A 35-yr-old G4AB3PO patient presenting at 10 wk of pregnancy with severe incapacitating lumbar radiculopathy is described. Magnetic resonance imaging, selected by the patient as a diagnostic option, demonstrated a clinically suspected large midline HNP at the L5-S1 level. In the past, visualizing the presence of a HNP during pregnancy by either computerized axial tomography scan or myelography has exposed the fetus to ionizing radiation. However, magnetic resonance imaging now permits a more detailed evaluation without similar x-ray exposure. To date, no recognized biologic effect of MRI on the developing fetus has been reported. Although the long-term effects of an magnetic resonance imaging on the developing fetus have not been conclusively evaluated, its potential for accurate diagnosis and subsequent patient management, as well as planning the delivery, appears to outweigh any recognized hazard to the developing fetus. PMID:7873115

LaBan, M M; Viola, S; Williams, D A; Wang, A M

1995-01-01

261

Magnetic resonance imaging pattern recognition in hypomyelinating disorders  

PubMed Central

Hypomyelination is observed in the context of a growing number of genetic disorders that share clinical characteristics. The aim of this study was to determine the possible role of magnetic resonance imaging pattern recognition in distinguishing different hypomyelinating disorders, which would facilitate the diagnostic process. Only patients with hypomyelination of known cause were included in this retrospective study. A total of 112 patients with Pelizaeus–Merzbacher disease, hypomyelination with congenital cataract, hypomyelination with hypogonadotropic hypogonadism and hypodontia, Pelizaeus–Merzbacher-like disease, infantile GM1 and GM2 gangliosidosis, Salla disease and fucosidosis were included. The brain scans were rated using a standard scoring list; the raters were blinded to the diagnoses. Grouping of the patients was based on cluster analysis. Ten clusters of patients with similar magnetic resonance imaging abnormalities were identified. The most important discriminating items were early cerebellar atrophy, homogeneity of the white matter signal on T2-weighted images, abnormal signal intensity of the basal ganglia, signal abnormalities in the pons and additional T2 lesions in the deep white matter. Eight clusters each represented mainly a single disorder (i.e. Pelizaeus–Merzbacher disease, hypomyelination with congenital cataract, hypomyelination with hypogonadotropic hypogonadism and hypodontia, infantile GM1 and GM2 gangliosidosis, Pelizaeus–Merzbacher-like disease and fucosidosis); only two clusters contained multiple diseases. Pelizaeus–Merzbacher-like disease was divided between two clusters and Salla disease did not cluster at all. This study shows that it is possible to separate patients with hypomyelination disorders of known cause in clusters based on magnetic resonance imaging abnormalities alone. In most cases of Pelizaeus–Merzbacher disease, hypomyelination with congenital cataract, hypomyelination with hypogonadotropic hypogonadism and hypodontia, Pelizaeus–Merzbacher-like disease, infantile GM1 and GM2 gangliosidosis and fucosidosis, the imaging pattern gives clues for the diagnosis. PMID:20881161

Steenweg, Marjan E.; Vanderver, Adeline; Blaser, Susan; Bizzi, Alberto; de Koning, Tom J.; Mancini, Grazia M. S.; van Wieringen, Wessel N.; Barkhof, Frederik; Wolf, Nicole I.

2010-01-01

262

Respiratory Amplitude Guided 4-Dimensional Magnetic Resonance Imaging  

SciTech Connect

Purpose: To evaluate the feasibility of prospectively guiding 4-dimensional (4D) magnetic resonance imaging (MRI) image acquisition using triggers at preselected respiratory amplitudes to achieve T{sub 2} weighting for abdominal motion tracking. Methods and Materials: A respiratory amplitude-based triggering system was developed and integrated into a commercial turbo spin echo MRI sequence. Initial feasibility tests were performed on healthy human study participants. Four respiratory states, the middle and the end of inhalation and exhalation, were used to trigger 4D MRI image acquisition of the liver. To achieve T{sub 2} weighting, the echo time and repetition time were set to 75 milliseconds and 4108 milliseconds, respectively. Single-shot acquisition, together with parallel imaging and partial k-space imaging techniques, was used to improve image acquisition efficiency. 4D MRI image sets composed of axial or sagittal slices were acquired. Results: Respiratory data measured and logged by the MRI scanner showed that the triggers occurred at the appropriate respiratory levels. Liver motion could be easily observed on both 4D MRI image datasets by sensing either the change of liver in size and shape (axial) or diaphragm motion (sagittal). Both 4D MRI image datasets were T{sub 2}-weighted as expected. Conclusions: This study demonstrated the feasibility of achieving T{sub 2}-weighted 4D MRI images using amplitude-based respiratory triggers. With the aid of the respiratory amplitude-based triggering system, the proposed method is compatible with most MRI sequences and therefore has the potential to improve tumor-tissue contrast in abdominal tumor motion imaging.

Hu, Yanle, E-mail: yhu@radonc.wustl.edu [Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri (United States)] [Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri (United States); Caruthers, Shelton D. [Department of Medicine, Washington University School of Medicine, St. Louis, Missouri (United States)] [Department of Medicine, Washington University School of Medicine, St. Louis, Missouri (United States); Low, Daniel A. [Department of Radiation Oncology, University of California Los Angeles, Los Angeles, California (United States)] [Department of Radiation Oncology, University of California Los Angeles, Los Angeles, California (United States); Parikh, Parag J.; Mutic, Sasa [Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri (United States)] [Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri (United States)

2013-05-01

263

Magnetic resonance imaging of the heart: positioning and gradient angle selection for optimal imaging planes  

SciTech Connect

Electrocardiographically gated magnetic resonance images were acquired in 20 subjects using a spin-echo pulse sequence. For optimizing the display of cardiac anatomy, a technique was developed which uses patients positioning in addition to alteration of gradient angle to select image planes. High-quality images were acquired in three basic cardiac projections: (1) the long axis of the left ventricle, through the aortic valve and apex, parallel to the interventricular septum, (2) the long axis of the left ventricle, perpendicular to the septum, and (3) the short axis of the left ventricle at multiple levels including outflow, papillary muscle, and apex. Images of the aorta included axial images at multiple levels and long-axis images oriented to display the plane of the aortic arch. Images of these planes are easily achieved and, in contrast to standard images orthogonal to the chest wall, provide a reproductible and logical display of cardiac anatomy.

Dinsmore, R.E.; Wismer, G.L.; Levine, R.A.; Okada, R.D.; Brady, T.J.

1984-12-01

264

Ferritin reporter used for gene expression imaging by magnetic resonance  

SciTech Connect

Magnetic resonance imaging (MRI) is a minimally invasive way to provide high spatial resolution tomograms. However, MRI has been considered to be useless for gene expression imaging compared to optical imaging. In this study, we used a ferritin reporter, binding with biogenic iron, to make it a powerful tool for gene expression imaging in MRI studies. GL261 mouse glioma cells were over-expressed with dual-reporter ferritin-DsRed under {beta}-actin promoter, then gene expression was observed by optical imaging and MRI in a brain tumor model. GL261 cells expressing ferritin-DsRed fusion protein showed enhanced visualizing effect by reducing T2-weighted signal intensity for in vitro and in vivo MRI studies, as well as DsRed fluorescence for optical imaging. Furthermore, a higher contrast was achieved on T2-weighted images when permeating the plasma membrane of ferritin-DsRed-expressing GL261. Thus, a ferritin expression vector can be used as an MRI reporter to monitor in vivo gene expression.

Ono, Kenji; Fuma, Kazuya; Tabata, Kaori [Department of Brain Functions, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi 464-8601 (Japan)] [Department of Brain Functions, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi 464-8601 (Japan); Sawada, Makoto, E-mail: msawada@riem.nagoya-u.ac.jp [Department of Brain Functions, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi 464-8601 (Japan)] [Department of Brain Functions, Division of Stress Adaptation and Protection, Research Institute of Environmental Medicine, Nagoya University, Nagoya, Aichi 464-8601 (Japan)

2009-10-23

265

UV imaging of biochips based on resonant grating  

NASA Astrophysics Data System (ADS)

In the frame of biological threat, security systems require label free biochips for rapid detection. Biosensors enable to detect biological interactions, between probes localized at the surface of a chip, and targets present in the sample solution. Here, we present an optical transduction, enabling 2D imaging, and consequently parallel detection of several reactions. It is based on the absorption of biological molecules in the UV domain. Thus, it is based on an intrinsic property of biological molecules and does not require any labelling of the biological molecules. DNA and proteins absorb UV light at 260 and 280 nm respectively. Sensitivity is a major requirement of biosensing devices. Configurations leading to enhancement of the interaction between light and biological molecules are of interest. For a better sensitivity, resonant grating structures are then studied. They enable to confine the electric field close to the biological layer. Imaging of resonant grating is not largely studied, even for visible wavelengths, but it results in good sensitivity. The protein used in this study is the methionyl-tRNA synthetase. Its absorption is representative of protein absorption, and it can then serve as a model for immunological detection. The best experimental contrast due to a monolayer of proteins is 40%. With data processing currently employed for biochip imaging: average on several acquisitions and on all the pixels imaging the biological spots, the device is able to detect a surface density of proteins in the 10 pg/mm range.

Bougot-Robin, Kristelle; Reverchon, Jean-Luc; Benisty, Henri; Fromant, Michel; Plateau, Pierre

2010-04-01

266

Image fusion of magnetocardiography and magnetic resonance imaging to correlate functional and anatomical imaging of the heart  

Microsoft Academic Search

Magnetic Resonance Imaging (MRI) is the most suitable method to correlate magnetocardiographic (MCG) localization results to anatomical structures of the heart. The study presented in this paper was conducted to determine the accuracy of positioning and coordinate transfer between MCG and MRI. The results show that the accuracy of image fusion of the two methods is in the range of

Werner Moshage; Stephan Achenbach; Stephan Horn; Kurt Bachmann; Uwe Weber; Siegfried Schneider; Matthias Gebhardt

1992-01-01

267

The rotating biplanar linac-magnetic resonance imaging system.  

PubMed

We have successfully built linac-magnetic resonance imaging (MR) systems based on a linac waveguide placed between open MR planes (perpendicular) or through the central opening of one of the planes (parallel) to improve dosimetric properties. It rotates on a gantry to irradiate at any angle. Irradiation during MR imaging and automatic 2-dimensional MR image-based target tracking and automatic beam steering to the moving target have been demonstrated with our systems. The functioning whole-body system (0.6-T MR and 6-MV linac) has been installed in an existing clinical vault without removing the walls or the ceiling and without the need of a helium exhaust vent. PMID:24931093

Fallone, Biagio Gino

2014-07-01

268

Magnetic resonance imaging of transfusional hepatic iron overload.  

PubMed

The transfusional iron overload in 11 adult patients suffering from haematological malignancy was studied in 14 consecutive 1.0 Tesla magnetic resonance imaging (MRI) studies. Routine T1- and T2-weighted spin echo sequences and a fat suppressed sequence (STIR) were used. The ratio from a region of interest of the liver parenchyma and from a manganese chloride reference phantom was measured. There was a definite difference between the signal ratio from the haematological patient group and the control group (p = 0.0001). The patients showed a diminished signal ratio in all pulse sequences used. There was a statistically significant inverse linear correlation between the number of transfused red cell units and the signal ratio in the T1-weighted (p = 0.03) and the T2-weighted (p = 0.03) images. A definite decrease of the effect is found after 20-30 red cell unit transfusions in T2-weighted and STIR images. PMID:8173872

Bondestam, S; Lamminen, A; Anttila, V J; Ruutu, T; Ruutu, P

1994-04-01

269

The Spleen Revisited: An Overview on Magnetic Resonance Imaging  

PubMed Central

Despite being well visualized by different cross-sectional imaging techniques, the spleen is many times overlooked during the abdominal examination. The major reason is the low frequency of splenic abnormalities, the majority consisting of incidental findings. There has been a steady increase in the number of performed abdominal magnetic resonance imaging (MRI) studies; therefore, it is important to be familiar to the major MRI characteristics of disease processes involving the spleen, in order to interpret the findings correctly, reaching whenever possible the appropriate diagnosis. The spleen may be involved in several pathologic conditions like congenital diseases, trauma, inflammation, vascular disorders and hematologic disorders, benign and malignant tumors, and other disease processes that focally or diffusely affect the spleen. This paper presents a description and representative MRI images for many of these disorders. PMID:24377046

Palas, João; Matos, António P.; Ramalho, Miguel

2013-01-01

270

Novel technique in the segmentation of magnetic resonance image  

NASA Astrophysics Data System (ADS)

In this investigation, automatic image segmentation is carried out on magnetic resonance image (MRI). A novel technique based on the maximum minimum measure is devised. The measure is improved by combining the smoothing and counting processes, and then normalizing the number of maximum and minimum positions over the region of interest (ROI). Two parameters (MM_H and MM_V) are generated and used for the segmentation. The technique is tested on some brain MRIs of a human male from the Visible Human Project of the National Library of Medicine, National Institutes of Health, USA. Preliminary results indicate that the maximum minimum measure can provide effective parameters for human tissue characterization and image segmentation with an added advantage of faster computation.

Chan, Kwok-Leung

1996-04-01

271

Neuroenteric cysts of the brain-comprehensive magnetic resonance imaging  

PubMed Central

Neuroenteric cysts are developmental cysts that should be differentiated from other, more common non-neoplastic cysts as well as cystic neoplasms. While these lesions may have varied imaging findings, T1 hyperintense prepontine lesion due to mucinous/proteinaceous content is characteristic. Location and imaging characteristics aid in formulating the correct diagnosis of neuroepithelial/neuroenteric cysts. Magnetic resonance spectroscopy (MRS) has the specific finding of N-Acetyl Aspartate (NAA)-like peak at 2.02 ppm which is not seen in other cystic lesions. In this study, we aim to discuss the imaging findings of these lesions on conventional and advanced MRI findings and provide radiologic-pathologic correlation. We also briefly describe the pathogenesis, embryology and radiological differential diagnoses of these cysts. PMID:24082482

Hingwala, Divyata R; Radhakrishnan, Neelima; Kesavadas, Chandrasekharan; Thomas, Bejoy; Kapilamoorthy, Tirur Raman; Radhakrishnan, Vishnupuri V

2013-01-01

272

Bias correction for magnetic resonance images via joint entropy regularization.  

PubMed

Due to the imperfections of the radio frequency (RF) coil or object-dependent electrodynamic interactions, magnetic resonance (MR) images often suffer from a smooth and biologically meaningless bias field, which causes severe troubles for subsequent processing and quantitative analysis. To effectively restore the original signal, this paper simultaneously exploits the spatial and gradient features of the corrupted MR images for bias correction via the joint entropy regularization. With both isotropic and anisotropic total variation (TV) considered, two nonparametric bias correction algorithms have been proposed, namely IsoTVBiasC and AniTVBiasC. These two methods have been applied to simulated images under various noise levels and bias field corruption and also tested on real MR data. The test results show that the proposed two methods can effectively remove the bias field and also present comparable performance compared to the state-of-the-art methods. PMID:24212018

Wang, Shanshan; Xia, Yong; Dong, Pei; Luo, Jianhua; Huang, Qiu; Feng, Dagan; Li, Yuanxiang

2014-01-01

273

Molecular Imaging in Cardiovascular Magnetic Resonance Imaging: Current Perspective and Future Potential  

PubMed Central

The development of novel imaging agents and techniques is allowing some biological events to be imaged in vivo with magnetic resonance imaging (MRI) at the cellular and subcellular level. In this paper, the use of novel gadolinium chelates and superparamagnetic iron oxide nanoparticles for molecular MRI of the cardiovascular system is extensively reviewed. The physical properties of these imaging agents and the pulse sequences best suited to their visualization are extensively discussed. The application of molecular MRI in diseases of the vasculature and myocardium is then reviewed. The clinical experience to date, as well as the promise and potential impact of molecular MRI, is extensively discussed. PMID:18690161

Sosnovik, David E.

2008-01-01

274

Transurethral prostate magnetic resonance elastography: prospective imaging requirements.  

PubMed

Tissue stiffness is known to undergo alterations when affected by prostate cancer and may serve as an indicator of the disease. Stiffness measurements can be made with magnetic resonance elastography performed using a transurethral actuator to generate shear waves in the prostate gland. The goal of this study was to help determine the imaging requirements of transurethral magnetic resonance elastography and to evaluate whether the spatial and stiffness resolution of this technique overlapped with the requirements for prostate cancer detection. Through the use of prostate-mimicking gelatin phantoms, frequencies of at least 400 Hz were necessary to obtain accurate stiffness measurements of 10 mm diameter inclusions, but the detection of inclusions with diameters as small as 4.75 mm was possible at 200 Hz. The shear wave attenuation coefficient was measured in vivo in the canine prostate gland, and was used to predict the detectable penetration depth of shear waves in prostate tissue. These results suggested that frequencies below 200 Hz could propagate to the prostate boundary with a signal to noise ratio (SNR) of 60 and an actuator capable of producing 60 ?m displacements. These requirements are achievable with current imaging and actuator technologies, and motivate further investigation of magnetic resonance elastography for the targeting of prostate cancer. PMID:20882673

Arani, Arvin; Plewes, Donald; Chopra, Rajiv

2011-02-01

275

A possible application of magnetic resonance imaging for pharmaceutical research.  

PubMed

Magnetic resonance imaging (MRI) is a non-destructive and non-invasive method, the experiment can be conducted in situ and allows the studying of the sample and the different processes in vitro or in vivo. 1D, 2D or 3D imaging can be undertaken. MRI is nowadays most widely used in medicine as a clinical diagnostic tool, but has still seen limited application in the food and pharmaceutical sciences. The different imaging pulse sequences of MRI allow to image the processes that take place in a wide scale range from ms (dissolution of compact tablets) to hours (hydration of drug delivery systems) for mobile as well as for rigid spins, usually protons. The paper gives examples of MRI application of in vitro imaging of pharmaceutical dosage based on hydroxypropyl methylcellulose which have focused on water-penetration, diffusion, polymer swelling, and drug release, characterized with respect to other physical parameters such as pH and the molecular weight of polymer. Tetracycline hydrochloride was used as a model drug. NMR imaging of density distributions and fast kinetics of the dissolution behavior of compact tablets is presented for paracetamol tablets. PMID:21195171

Kowalczuk, Joanna; Tritt-Goc, Jadwiga

2011-03-18

276

Magnetic resonance imaging and contrast enhancement. Scientific report  

SciTech Connect

Chapters II through VI of this report discuss: Relaxation of Nuclear Spins; Echo Techniques; Basic Imaging Pulse Sequences; Partial Saturation Recovery; Inversion Recovery; Spin Echo; Effects of Pulse Sequence on Image Contrast; Contrast Agents; Theoretical Aspects; Pharmacokinetics and Toxicity; and Physiological Rationale for Agent Selection. One of the major goals in all medical imaging techniques is to maximize one's ability to visualize and differentiate adjacent tissue regions in the body on the basis of differences in anatomy, physiology, or various pathological processes. Magnetic resonance (MR) imaging offers distinct advantages over conventional x-ray imaging because of the possibility of selecting specific pulse sequences that can differentiate adjacent structures on the basis of differences in proton density, T/sub 1/ or T/sub 2/ relaxation rates, or flow. As a result of applying these various pulse sequences, numerous images have been obtained of the brain and other organs that demonstrate considerably more-detailed anatomical structure than had previously been available with computerized tomography, ultrasound, or nuclear medicine techniques. In some situations it is clearly superior, such as in the diagnosis of multiple sclerosis.

Swenberg, C.E.; Movius, E.G.

1988-01-01

277

ADVANCED MAGNETIC RESONANCE IMAGING OF CEREBRAL CAVERNOUS MALFORMATIONS  

PubMed Central

Objective We sought to assess the appearance of cerebral cavernous malformations (CCMs) on magnetic resonance (MR) imaging in murine Ccm1 and Ccm2 gene knockout models, and to develop a technique of lesion localization for correlative pathobiologic studies Methods Brains from eighteen CCM mutant mice (Ccm1+/-Trp53-/- and Ccm2+/-Trp53-/-) and 28 controls were imaged by gradient recalled echo (T2*)-weighted MR at 4.7 T and 14.1 T in vivo and/or ex vivo. After MR imaging, the brains were removed and stained with hematoxylin and eosin and cells were laser microdissected for molecular biologic studies. Results T2*-weighted MR imaging of brains in vivo and ex vivo revealed lesions similar to human CCMs in mutant mice, but not in control animals. Stereotactic localization and hematoxylin and eosin-staining of correlative tissue sections confirmed lesion histology, and revealed other areas of dilated capillaries in the same brains. Some lesions were identified by MR imaging at 14.1 T, but not at 4.7 T. PCR amplification from Ccm1 and ?-actin genes was demonstrated from nucleic acids extracted from laser microdissected lesional and perilesional cells. Conclusions The high field MR imaging techniques offer new opportunities for further investigation of disease pathogenesis in vivo, and the localization, staging and histobiologic dissection of lesions, including the presumed earliest stages of CCM lesion development. PMID:18981891

Shenkar, Robert; Venkatasubramanian, Palamadai N.; Wyrwicz, Alice M.; Zhao, Jin-cheng; Shi, Changbin; Akers, Amy; Marchuk, Douglas A.; Awad, Issam A.

2008-01-01

278

Stroke Assessment with Diffusional Kurtosis Imaging  

PubMed Central

Background and Purpose Despite being the gold standard technique for stroke assessment, conventional diffusion magnetic resonance imaging (dMRI) provides only partial information about tissue microstructure. Diffusional kurtosis imaging (DKI) is an advanced dMRI method that yields, in addition to conventional diffusion information, the diffusional kurtosis (K), which may help improve characterization of tissue microstructure. In particular, this additional information permits the description of white matter (WM) in terms of WM-specific diffusion metrics (WMM). The goal of this study is to elucidate possible biophysical mechanisms underlying ischemia using these new WMM. Methods We performed a retrospective review of clinical and DKI data of forty-four acute/subacute ischemic stroke patients. Patients with a history of brain neoplasm or intracranial hemorrhages were excluded from this study. ROI analysis was performed to measure percent change of diffusion metrics in ischemic WM lesions compared to the contralateral hemisphere. Results K maps exhibit distinct ischemic lesion heterogeneity that is not apparent on apparent diffusion coefficient (ADC) maps. K metrics also have significantly higher absolute percent change than complementary conventional diffusion metrics. Our WMM reveal an increase in axonal density and a larger decrease in the intra-axonal (Da) compared to extra-axonal (De) diffusion microenvironment of the ischemic WM lesion. Conclusions The well-known decrease in the ADC of WM following ischemia is found to be mainly driven by a significant drop in Da. Our results suggest that ischemia preferentially alters intra-axonal environment, consistent with a proposed mechanism of focal enlargement of axons known as axonal swelling or beading. PMID:22933581

Hui, Edward S.; Fieremans, Els; Jensen, Jens H.; Tabesh, Ali; Feng, Wuwei; Bonilha, Leonardo; Spampinato, Maria V.; Adams, Robert; Helpern, Joseph A.

2012-01-01

279

Innovative computing for diagnoses from medical, magnetic-resonance imaging  

SciTech Connect

The author presents a final report on a Laboratory-Directed Research and Development (LDRD) project, Innovative Computing for Diagnoses from Medical, Magnetic-Resonance Imaging, performed during fiscal years 1992 and 1993. The project defined a role for high-performance computing in surgery: the supercomputer can automatically summarize the three-dimensional extents of lesions and other clinically-relevant structures, and can deliver these summaries to workstation-based, augmented-reality environments at the clinical site. The author developed methods and software to make these summaries from the digital data already acquired using clinical, magnetic-resonance machines. In joint work with Albuquerque`s Department of Veterans Affairs Hospital, the author applied this work, and obtained a basis for planning, for rehearsal, and for guidance during surgery.

Diegert, C.

1997-01-01

280

[Fetal magnetic resonance imaging evaluation of congenital diaphragmatic hernia].  

PubMed

A diaphragmatic hernia is defined as the protrusion of abdominal viscera into the thoracic cavity through a normal or pathological orifice. The herniated viscera compress the lungs, resulting in pulmonary hypoplasia and secondary pulmonary hypertension, which are the leading causes of neonatal death in patients with congenital diaphragmatic hernia. Congenital diaphragmatic hernia is diagnosed by sonography in routine prenatal screening. Although magnetic resonance imaging is fundamentally used to determine whether the liver is located within the abdomen or has herniated into the thorax, it also can provide useful information about other herniated structures and the degree of pulmonary hypoplasia. The aim of this article is to review the fetal magnetic resonance findings for congenital diaphragmatic hernia and the signs that enable us to establish the neonatal prognosis when evaluating pulmonary hypoplasia. PMID:23523414

Sebastià, C; Garcia, R; Gomez, O; Paño, B; Nicolau, C

2014-01-01

281

Magnetic resonance imaging and electromyography as indexes of muscle function  

NASA Technical Reports Server (NTRS)

A hypothesis is tested that exercise-induced magnetic resonance (MR) contrast shifts would relate to electromyography (EMG) amplitude if both measures reflect muscle use during exercise. Both magnetic resonance images (MRI) and EMG data were obtained for separate eccentric (ECC) and cocentric (CON) exercise of increasing intensity for seven subjects 30-32 yr old. CON and ECC actions caused increased integrated EMG (IEMG) and T2 values which were strongly related with relative resistance. The rate of increase and absolute value of both T2 and IEMG were found to be greater for CON than for ECC actions. For both actions IEMG and T2 were correlated. Data obtained suggest that surface IEMG accurately reflects the contractile behavior of muscle and exercise-induced increases in MRI T2 values reflect certain processes that scale with muscle use.

Adams, Gregory R.; Duvoisin, Marc R.; Dudley, Gary A.

1992-01-01

282

Magnetic resonance imaging safety of deep brain stimulator devices.  

PubMed

Magnetic resonance imaging (MRI) has become the standard of care for the evaluation of different neurological disorders of the brain and spinal cord due to its multiplanar capabilities and excellent soft tissue resolution. With the large and increasing population of patients with implanted deep brain stimulation (DBS) devices, a significant proportion of these patients with chronic neurological diseases require evaluation of their primary neurological disease processes by MRI. The presence of an implanted DBS device in a magnetic resonance environment presents potential hazards. These include the potential for induction of electrical currents or heating in DBS devices, which can result in neurological tissue injury, magnetic field-induced device migration, or disruption of the operational aspects of the devices. In this chapter, we review the basic physics of potential interactions of the MRI environment with implanted DBS devices, summarize results from phantom studies and clinical series, and discuss present recommendations for safe MRI in patients with implanted DBS devices. PMID:24112886

Oluigbo, Chima O; Rezai, Ali R

2013-01-01

283

Parallel Magnetic Resonance Imaging Acquisition and Reconstruction: Application to Functional and Spectroscopic Imaging in Human Brain  

Microsoft Academic Search

\\u000a Magnetic resonance imaging (MRI) has contributed significantly to modern cancer diagnosis and treatment planning because of\\u000a its noninvasive nature, versatile image contrast, and high spatiotemporal resolution. For decades, the quest for higher sensitivity\\u000a and greater spatial and\\/or temporal resolution has been approached by means of increasing major field strengths, enhancing\\u000a gradient performance, and improving radio frequency (RF) technology. In this

Fa-Hsuan Lin; Shang-Yueh Tsai

284

Resonant marker design and fabrication techniques for device visualization during interventional magnetic resonance imaging.  

PubMed

Abstract Magnetic resonance imaging (MRI) has great potential as an imaging modality for guiding minimally invasive interventions because of its superior soft tissue contrast and the possibility of arbitrary slice positioning while avoiding ionizing radiation and nephrotoxic iodine contrast agents. The major constraints are: limited patient access, the insufficient assortment of compatible instruments and the difficult device visualization compared to X-ray based techniques. For the latter, resonant MRI markers, fabricated by using the wire-winding technique, have been developed. This fabrication technique serves as a functional model but has no clinical use. Thus, the aim of this study is to illustrate a four-phase design process of resonant markers involving microsystems technologies. The planning phase comprises the definition of requirements and the simulation of electromagnetic performance of the MRI markers. The following technologies were considered for the realization phase: aerosol-deposition process, hot embossing technology and thin film technology. The subsequent evaluation phase involves several test methods regarding electrical and mechanical characterization as well as MRI visibility aspects. The degree of fulfillment of the predefined requirements is determined within the analysis phase. Furthermore, an exemplary evaluation of four realized MRI markers was conducted, focusing on the performance within the MRI environment. PMID:25460277

Kaiser, Mandy; Detert, Markus; Rube, Martin A; El-Tahir, Abubakr; Elle, Ole Jakob; Melzer, Andreas; Schmidt, Bertram; Rose, Georg H

2014-12-01

285

Functional magnetic resonance imaging of horizontal rectus muscles in esotropia  

PubMed Central

PURPOSE Monkey neurophysiology suggests that changes in neural drive rather than extraocular muscle structure underlie sensory-induced strabismus. If this is true, then extraocular muscle structure should be normal. We used magnetic resonance imaging to measure horizontal rectus muscle size and contractility to determine whether muscle structure is a factor in human concomitant esotropia. METHODS High-resolution, quasicoronal plane magnetic resonance imaging was performed in target-controlled central gaze, abduction, and adduction in 13 orthotropic controls (mean age, 38 ± 19 years) and 12 adults (mean age, 52 ± 16 years) who had concomitant esotropia averaging 28? ± 18? at distance. Thyroid ophthalmopathy was excluded. Horizontal rectus muscle cross sections were determined in 6 contiguous, 2-mm-thick midorbital image planes. Contractility was computed in each plane as the difference in cross section from contraction to relaxation. RESULTS Medial rectus muscle cross sections in multiple planes averaged up to 39% larger in esotropic patients than in controls (P <0.005), whereas lateral rectus muscle cross sections in esotropia were up to 28% larger but only significantly larger in one plane (P <0.02). Medial rectus contractility was increased by up to 60% in esotropic patients (P <0.005), whereas lateral rectus contractility in esotropia was slightly but not significantly supernormal. CONCLUSIONS Medial rectus muscle size is supernormal and lateral rectus muscle size is not subnormal in concomitant esotropia. This finding indicates that human concomitant esotropia is associated with peripheral muscular abnormality. PMID:23352382

Schoeff, Kirsta; Chaudhuri, Zia; Demer, Joseph L.

2014-01-01

286

Magnetic resonance properties of hydrogen: imaging the posterior fossa  

SciTech Connect

Posterior fossa scans were performed on five healthy volunteers using a nuclear magnetic resonance (NMR) machine constructed by Thorn-EMI Ltd. Three different NMR scanning sequences were used. In the first, a type of saturation-recovery technique was used to produce images strongly dependent on the density of hydrogen nuclei, but with some dependence on the spin-lattice relaxation time (T/sub 1/). In the second, an inversion-recovery technique was used to produce images with a stronger dependence on the spin-lattice relaxation time. In the third, a spin-echo technique was used to obtain images with a dependence on the spin-spin relaxation time (T/sub 2/). All three types of NMR image were unaffected by bone artifact. Visualization of brain adjacent to the skull base was obtained without loss of detail due to partial-volume effect from bone. The saturation-recovery images highlighted arteries and veins that were clearly visible without the use of contrast agents. The inversion-recovery images showed remarkable gray-white matter differentiation enabling internal structure to be seen within the brainstem and cerebellum. The trigeminal nerve and ganglion were also seen outside the brain. Experience with the spin-echo technique is limited, but the images at the base of the brain show considerable soft-tissue detail. The NMR images of the posterior fossa in this study were comparable in quality to those obtained from a new rotate-rotate x-ray computed tomography machine and were superior in several respects.

Young, I.R. (Thorn-EMI Ltd., Middlesex, England); Burl, M.; Clarke, G.J.

1981-11-01

287

The fundamentals of fetal magnetic resonance imaging: Part 2.  

PubMed

Careful assessment of fetal anatomy by a combination of ultrasound and fetal magnetic resonance imaging offers the clinical teams and counselors caring for the patient information that can be critical for the management of both the mother and the fetus. In the second half of this 2-part review, we focus on space-occupying lesions in the fetal body. Because developing fetal tissues are programmed to grow rapidly, mass lesions can have a substantial effect on the formation of normal adjacent organs. Congenital diaphragmatic hernia and lung masses, fetal teratoma, and intra-abdominal masses are discussed, with an emphasis on differential etiologies and on fundamental management considerations. PMID:24974309

Plunk, Matthew R; Chapman, Teresa

2014-01-01

288

Magnetic resonance imaging by using nano-magnetic particles  

NASA Astrophysics Data System (ADS)

Magnetism and magnetic materials play a major role in various biological applications, such as magnetic bioseparation, magnetic resonance imaging (MRI), hyperthermia treatment of cancer and drug delivery. Among these techniques, MRI is a powerful method not only for diagnostic radiology but also for therapeutic medicine that utilizes a magnetic field and radio waves. Recently, this technique has contributed greatly to the promotion of the human quality life. Thus, this paper presents a short review of the physical principles and recent advances of MRI, as well as providing a summary of the synthesis methods and properties of contrast agents, like different core materials and surfactants.

Shokrollahi, H.; Khorramdin, A.; Isapour, Gh.

2014-11-01

289

Magnetic resonance imaging of abdominal and pelvic lymphadenopathy  

SciTech Connect

The authors report their experience with magnetic resonance imaging (MR) in 20 patients with CT-proved lymphadenopathy of the abdomen and pelvis. Signal intensity from abnormal nodes was intermediate between fat and muscle and was shown best in the spin-echo mode. Abnormal nodes were identified by their increased size and other morphological changes rather than by tissue characteristics established by signal intensity information. Lymphadenopathy due to lymphoma could not be differentiated from that due to metastases. MR detected all lymphadenopathy originally documented by CT and in addition easily distinguished blood vessels from lymph nodes; on the other hand, CT offered better spatial resolution and could be completed in less time.

Lee, J.K.T.; Heiken, J.P.; Ling, D.; Glazer, H.S.; Balfe, D.M.; Levitt, R.G.; Dixon, W.T.; Murphy, W.A. Jr.

1984-10-01

290

Magnetic resonance imaging findings of breast juvenile papillomatosis.  

PubMed

Juvenile papillomatosis is a rare disease affecting young women. Here we present magnetic resonance imaging features of two cases with histopathologically proven juvenile papillomatosis of the breast and review some of the relevant literature. Case 1 exhibited bilateral, well-bordered breast masses, with complex cystic and solid components. The kinetic evaluation showed continuous and plateau patterns. Case 2 featured a giant mass with a few cystic and many solid nodular components and filled the entire right breast. The kinetic evaluation showed a continuous curve. PMID:23475601

Durur-Subasi, Irmak; Alper, Fatih; Akcay, Mufide Nuran; Demirci, Elif; Gundogdu, Cemal

2013-06-01

291

Thalamus Segmentation from Diffusion Tensor Magnetic Resonance Imaging  

PubMed Central

We propose a semi-automatic thalamus and thalamus nuclei segmentation algorithm from Diffusion Tensor Magnetic Resonance Imaging (DT-MRI) based on the mean-shift algorithm. Comparing with existing thalamus segmentation algorithms which are mainly based on K-means algorithm, our mean-shift based algorithm is more flexible and adaptive. It does not assume a Gaussian distribution or a fixed number of clusters. Furthermore, the single parameter in the mean-shift based algorithm supports hierarchical clustering naturally. PMID:18274658

Duan, Ye; Li, Xiaoling; Xi, Yongjian

2007-01-01

292

The economics of functional magnetic resonance imaging: clinical and research.  

PubMed

It is difficult to justify maintaining a clinical functional magnetic resonance imaging (fMRI) program based solely on revenue generation. The use of fMRI is, therefore, based mostly in patient care considerations, leading to better outcomes. The high costs of the top-of-the-line equipment, hardware, and software needed for state-of-the-art fMRI and the time commitment by multiple professionals are not adequately reimbursed at a representative rate by current payor schemes for the Current Procedure Terminology codes assigned. PMID:25441510

Yousem, David M

2014-11-01

293

ROUTINE THREE-DIMENSIONAL MAGNETIC RESONANCE IMAGING OF JOINTS  

PubMed Central

Due to its high spatial resolution and excellent tissue contrast, magnetic resonance (MR) imaging has become the most commonly used imaging method to evaluate joints. Most musculoskeletal MR imaging is performed using two-dimensional fast spin-echo sequences. However, three-dimensional sequences have also been used for joint imaging and have the advantage of acquiring thin continuous slices through joints which reduces the effects of partial volume averaging. With recent advances in MR technology, three-dimensional sequences with isotropic resolution have been developed. These sequences allow high quality multi-planar reformat images to be obtained following a single acquisition, thereby eliminating the need to repeat sequences with identical tissue contrast in different planes. Preliminary results on the diagnostic performance of three-dimensional isotropic resolution sequences are encouraging. However, additional studies are needed to determine whether these sequences can replace currently used two-dimensional fast spin-echo sequences for providing comprehensive joint assessment in clinical practice. PMID:21448939

Kijowki, Richard; Gold, Garry E.

2011-01-01

294

Prostate cancer magnetic resonance imaging (MRI): multidisciplinary standpoint  

PubMed Central

Prostate cancer is the most common cancer diagnosed in men and a leading cause of death. Accurate assessment is a prerequisite for optimal clinical management and therapy selection of prostate cancer. There are several parameters and nomograms to differentiate between patients with clinically insignificant disease and patients in need of treatment. Magnetic resonance imaging (MRI) is a technique which provides more detailed anatomical images due to high spatial resolution, superior contrast resolution, and multiplanar capability. State-of-the-art MRI techniques, such as diffusion weighted imaging (DWI), MR spectroscopic imaging (MRSI), dynamic contrast enhanced MRI (DCE-MRI), improve interpretation of prostate cancer imaging. In this article, we review the major role of MRI in the advanced management of prostate cancer to noninvasively improve tumor staging, biologic potential, treatment planning, therapy response, local recurrence, and to guide target biopsy for clinical suspected cancer with previous negative biopsy. Finally, future challenges and opportunities in prostate cancer management in the area of functional MRI are discussed as well. PMID:23630657

Li, Liang; Feng, Zhaoyan; Hu, Zhiquan; Wang, Guoping; Yuan, Xianglin; Wang, He; Hu, Daoyu

2013-01-01

295

Echo-Planar Imaging: Magnetic Resonance Imaging in a Fraction of a Second  

NASA Astrophysics Data System (ADS)

Progress has recently been made in implementing magnetic resonance imaging (MRI) techniques that can be used to obtain images in a fraction of a second rather than in minutes. Echo-planar imaging (EPI) uses only one nuclear spin excitation per image and lends itself to a variety of critical medical and scientific applications. Among these are evaluation of cardiac function in real time, mapping of water diffusion and temperature in tissue, mapping of organ blood pool and perfusion, functional imaging of the central nervous system, depiction of blood and cerebrospinal fluid flow dynamics, and movie imaging of the mobile fetus in utero. Through shortened patient examination times, higher patient throughput, and lower cost per MRI examination, EPI may become a powerful tool for early diagnosis of some common and potentially treatable diseases such as ischemic heart disease, stroke, and cancer.

Stehling, Michael K.; Turner, Robert; Mansfield, Peter

1991-10-01

296

An Interactive Tool for Segmentation, Visualization, and Navigation of Magnetic Resonance Images  

E-print Network

An Interactive Tool for Segmentation, Visualization, and Navigation of Magnetic Resonance Images for the segmentation, visualization and navigation of magnetic resonance (MR) images is presented. Previous work has shown the hierarchical self-organizing map (HSOM) to be highly effective in segmenting MR images

Bhandarkar, Suchendra "Suchi" M.

297

Synthesis of gadolinium oxide magnetoliposomes for magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

A method for the synthesis of gadolinium oxide magnetoliposomes, i.e., nanosized gadolinium oxide magnetic particles coated by a phospholipid membrane, is presented. Magnetoliposomes were prepared by reacting lauric acid coated gadolinium oxide nanoparticles with dimyristoylphosphatidylcholine liposomes prepared using a direct injection method. The gadolinium oxide magnetoliposomes were characterized using transmission electron microscopy imaging, x-ray diffraction, and fluorescence. The magnetic properties of the magnetoliposomes were investigated with a superconducting quantum interference device magnetometer and nuclear magnetic resonance (NMR) spectrometry. Our results indicate that the magnetoliposomes contain approximately spherical nanoparticles averaging 20 nm in diameter. The occurrence of a phospholipid bilayer surrounding the magnetic particles is confirmed both by transmission electron micrographs of samples negatively stained with uranyl acetate and by digital fluorescence imaging microscopy measurements of magnetoliposomes labeled with fluorescein. The particles are paramagnetic at room temperature. NMR measurements show that the ratio between the relaxivities of the particles depends largely on their preparation.

Roberts, Danielle; Zhu, Weibe L.; Frommen, Christoph M.; Rosenzweig, Zeev

2000-05-01

298

Clinical significance of magnetic resonance imaging findings in rectal cancer  

PubMed Central

Staging of rectal cancer is essential to help guide clinicians to decide upon the correct type of surgery and determine whether or not neoadjuvant therapy is indicated. Magnetic resonance imaging (MRI) is currently one of the most accurate modalities on which to base treatment decisions for patients with rectal cancer. MRI can accurately detect the mesorectal fascia, assess the invasion of the mesorectum or surrounding organs and predict the circumferential resection margin. Although nodal disease remains a difficult radiological diagnosis, new lymphographic agents and diffusion weighted imaging may allow identification of metastatic nodes by criteria other then size. In light of this, we have reviewed the literature on the accuracy of specific MRI findings for staging the local extent of primary rectal cancer. The aim of this review is to establish a correlation between MRI findings, prognosis, and available treatment options. PMID:21532870

Bellows, Charles F; Jaffe, Bernard; Bacigalupo, Lorenzo; Pucciarelli, Salvatore; Gagliardi, Guiseppe

2011-01-01

299

Direct Neural Imaging using Ultra-Low Field Magnetic Resonance  

NASA Astrophysics Data System (ADS)

An enduring challenge in neuroscience is the accurate in vivo mapping of neural activity with high spatial and temporal resolution. A method being developed by our group tries to meet this challenge by using Ultra-Low Field (ULF) MRI. Other groups have attempted direct neural imaging (DNI) using high field MRI. However, the use of ULF presents two advantages. First, the susceptibility artifact at high fields, which masks the DNI signal, is negligible at low fields. Second, the reduced Larmor frequency at ULF may overlap with the frequency spectrum of the neural magnetic field, resonantly enhancing the MRI signal. In this presentation, I will first show our custom-built ULF MRI setups that have successfully produced ULF anatomical images. I will then highlight the numerous studies we have done to investigate the feasibility of DNI with these systems, including both experimental and theoretical studies.

Maskaly, Karlene; Espy, Michelle; Flynn, Mark; Gomez, John; Kraus, Robert; Matlashov, Andrei; Mosher, John; Newman, Shaun; Owens, Tuba; Peters, Mark; Sandin, J.; Schultz, Larry; Urbaitis, Algis; Volegov, Petr; Zotev, Vadim

2009-03-01

300

The role of magnetic resonance imaging in hypertrophic cardiomyopathy  

PubMed Central

Hypertrophic cardiomyopathy (HCM) is the most common inheritable cardiac disorder, with an estimated prevalence of 1:500 in the general population. Most cases of HCM are phenotypically expressed in adolescence or early adulthood but age-related penetrance with certain phenotypes is increasingly recognized. Clinical manifestations of HCM are usually the result of systolic and/or diastolic dysfunction, left ventricular outflow tract (LVOT) obstruction, arrhythmias and sudden cardiac death (SCD). In recent years magnetic resonance imaging (MRI) has become established as an important tool for the evaluation of suspected HCM as it can reliably establish the diagnosis, help distinguish HCM from other causes of left ventricular hypertrophy (LVH) and identify those patients at greatest risk of SCD. This article reviews the current status of MRI in the evaluation of the HCM patient including imaging protocols, disease characterization and the emerging role of MRI for risk stratification and proband screening. PMID:25392824

Elassaly, Mohamed; Ganeshan, Arul; Watkin, Richard W.; Simpson, Helen

2014-01-01

301

3-D Display Of Magnetic Resonance Imaging Of The Spine  

NASA Astrophysics Data System (ADS)

The original data is produced through standard magnetic resonance imaging (MRI) procedures with a surface coil applied to the lower back of a normal human subject. The 3-D spine image data consists of twenty-six contiguous slices with 256 x 256 pixels per slice. Two methods for visualization of the 3-D spine are explored. One method utilizes a verifocal mirror system which creates a true 3-D virtual picture of the object. Another method uses a standard high resolution monitor to simultaneously show the three orthogonal sections which intersect at any user-selected point within the object volume. We discuss the application of these systems in assessment of low back pain.

Nelson, Alan C.; Kim, Yongmin; Haralick, Robert M.; Anderson, Paul A.; Johnson, Roger H.; DeSoto, Larry A.

1988-06-01

302

Pulmonary functional magnetic resonance imaging for paediatric lung disease.  

PubMed

A better understanding of the anatomic structure and physiological function of the lung is fundamental to understanding the pathogenesis of pulmonary disease and how to design and deliver better treatments and measure response to intervention. Magnetic resonance imaging (MRI) with the hyperpolarised noble gases helium-3 ((3)He) and xenon-129 ((129)Xe) provides both structural and functional pulmonary measurements, and because it does not require the use of x-rays or other ionising radiation, offers the potential for intensive serial and longitudinal studies in paediatric patients. These facts are particularly important in the evaluation of chronic lung diseases such as asthma and cystic fibrosis- both of which can be considered paediatric respiratory diseases with unmet therapy needs. This review discusses MRI-based imaging methods with a focus on hyperpolarised gas MRI. We also discuss the strengths and limitations as well as the future work required for clinical translation towards paediatric respiratory disease. PMID:23522599

Kirby, Miranda; Coxson, Harvey O; Parraga, Grace

2013-09-01

303

Grisel Syndrome: Pathophysiological Evidence from Magnetic Resonance Imaging Findings  

PubMed Central

Grisel syndrome is a condition of uncertain etiology characterized by a non-traumatic atlantoaxial subluxation following an infection in the head and neck region. Although first described in 1830, the exact pathophysiology of Grisel syndrome remains unclear. We present a case of atlantoaxial subluxation after acute lymphadenitis diagnosed with a dynamic computed tomography (CT) and magnetic resonance imaging (MRI). A previously healthy 9-year-old male patient presented with torticollis of sudden onset. Dynamic CT and MR imaging showed rotary atlantoaxial subluxation and inflammation surrounding the cervical spinal ligaments. A follow-up MRI of the cervical spine, taken 3 weeks after the onset of symptoms, showed a complete resolution of subluxation and inflammation surrounding the cervical spinal ligaments. In this case report, we support the hypothesis that an inflammation-induced laxity of the cervical ligaments is the pathologic key to Grisel syndrome using radiologic findings. PMID:24236260

Park, See-Hyun; Lee, Sang-Hee

2013-01-01

304

Simultaneous Magnetic Resonance Imaging and Consolidation Measurement of Articular Cartilage  

PubMed Central

Magnetic resonance imaging (MRI) offers the opportunity to study biological tissues and processes in a non-disruptive manner. The technique shows promise for the study of the load-bearing performance (consolidation) of articular cartilage and changes in articular cartilage accompanying osteoarthritis. Consolidation of articular cartilage involves the recording of two transient characteristics: the change over time of strain and the hydrostatic excess pore pressure (HEPP). MRI study of cartilage consolidation under mechanical load is limited by difficulties in measuring the HEPP in the presence of the strong magnetic fields associated with the MRI technique. Here we describe the use of MRI to image and characterize bovine articular cartilage deforming under load in an MRI compatible consolidometer while monitoring pressure with a Fabry-Perot interferometer-based fiber-optic pressure transducer. PMID:24803188

Wellard, Robert Mark; Ravasio, Jean-Philippe; Guesne, Samuel; Bell, Christopher; Oloyede, Adekunle; Tevelen, Greg; Pope, James M.; Momot, Konstantin I.

2014-01-01

305

Normal Canine Brain Maturation at Magnetic Resonance Imaging  

PubMed Central

The normal neonatal canine brain exhibits marked differences from that of the mature brain. With development into adulthood there is a decrease in relative water content and progressive myelination; these changes are observable with magnetic resonance (MR) imaging and are characterized by a repeatable and predictable time course. We characterized these developmental changes on common MR imaging sequences and identified clinically useful milestones of transition. To accomplish this, 17 normal dogs underwent MR imaging of the brain at various times after birth from 1 to 36 weeks. Sequences acquired were T1-weighted, T2-weighted, Fluid Attenuated Inversion Recovery, Short Tau Inversion Recovery and Diffusion Weighted Imaging sequences. The images were assessed subjectively for gray and white matter relative signal intensity and results correlated with histologic findings. The development of the neonatal canine brain follows a pattern that qualitatively matches that observed in humans, and which can be characterized adequately on T1-weighted and T2-weighted images. At birth, the relative gray matter to white matter signal intensity of the cortex is reversed from that of the adult with an isointense transition at 3–4 weeks on T1-weighted and 4–8 weeks on T2-weighted images. This is followed by the expected mature gray matter to white matter relative intensity that undergoes continued development to a mostly adult appearance by 16 weeks. On the Fluid Attenuated Inversion Recovery sequence the cortical gray and white matter exhibit an additional signal intensity reversal during the juvenile period that is due to the initial high relative water content at the subcortical white matter, with its marked T1 relaxation effect. PMID:20806866

Gross, Bill; Garcia-Tapia, David; Riedesel, Elizabeth; Ellinwood, Norman Matthew; Jens, Jackie K.

2010-01-01

306

Statistical reconstruction algorithms for continuous wave electron spin resonance imaging  

NASA Astrophysics Data System (ADS)

Electron spin resonance imaging (ESRI) is an important branch of ESR that deals with heterogeneous samples ranging from semiconductor materials to small live animals and even humans. ESRI can produce either spatial images (providing information about the spatially dependent radical concentration) or spectral-spatial images, where an extra dimension is added to describe the absorption spectrum of the sample (which can also be spatially dependent). The mapping of oxygen in biological samples, often referred to as oximetry, is a prime example of an ESRI application. ESRI suffers frequently from a low signal-to-noise ratio (SNR), which results in long acquisition times and poor image quality. A broader use of ESRI is hampered by this slow acquisition, which can also be an obstacle for many biological applications where conditions may change relatively quickly over time. The objective of this work is to develop an image reconstruction scheme for continuous wave (CW) ESRI that would make it possible to reduce the data acquisition time without degrading the reconstruction quality. This is achieved by adapting the so-called "statistical reconstruction" method, recently developed for other medical imaging modalities, to the specific case of CW ESRI. Our new algorithm accounts for unique ESRI aspects such as field modulation, spectral-spatial imaging, and possible limitation on the gradient magnitude (the so-called "limited angle" problem). The reconstruction method shows improved SNR and contrast recovery vs. commonly used back-projection-based methods, for a variety of simulated synthetic samples as well as in actual CW ESRI experiments.

Kissos, Imry; Levit, Michael; Feuer, Arie; Blank, Aharon

2013-06-01

307

Non-Hodgkin's lymphoma with left suprascapular neuropathy on magnetic resonance imaging.  

PubMed

Magnetic resonance imaging is gaining importance in the diagnosis of nerve and muscular disorders. The ability of magnetic resonance imaging to delineate the different muscles and the nerve in any plane has made the differentiation between the changes of neuropathy, denervation, and nerve entrapment possible. Although findings on magnetic resonance imaging are non-specific, their use, coupled with clinical symptoms and electromyographic findings, allow an accurate diagnosis to be made without resorting to invasive biopsies. PMID:12668827

Faridah, Y; Abdullah, B J J

2003-04-01

308

Whiplash injuries can be visible by functional magnetic resonance imaging  

PubMed Central

Whiplash trauma can result in injuries that are difficult to diagnose. Diagnosis is particularly difficult in injuries to the upper segments of the cervical spine (craniocervical joint [CCJ] complex). Studies indicate that injuries in that region may be responsible for the cervicoencephalic syndrome, as evidenced by headache, balance problems, vertigo, dizziness, eye problems, tinnitus, poor concentration, sensitivity to light and pronounced fatigue. Consequently, diagnosis of lesions in the CCJ region is important. Functional magnetic resonance imaging is a radiological technique that can visualize injuries of the ligaments and the joint capsules, and accompanying pathological movement patterns. Three severely injured patients that had been extensively examined without any findings of structural lesions were diagnosed by functional magnetic resonance imaging to have injuries in the CCJ region. These injuries were confirmed at surgery, and after surgical stabilization the medical condition was highly improved. It is important to draw attention to the urgent need to diagnose lesions and dysfunction in the CCJ complex and also improve diagnostic methods. PMID:16960637

Johansson, Bengt H

2006-01-01

309

Neuropathologic correlates of magnetic resonance imaging in multiple sclerosis.  

PubMed

The advent of magnetic resonance imaging (MRI) has revolutionized concepts of the pathogenesis of multiple sclerosis (MS). Magnetic resonance imaging provides the ability to delineate the evolution of the disease process over time; captured static snapshots can then be used in pathologic correlations studies. Certain patterns in the 2- or 3-dimensional MRI sphere correlate very well with similar patterns of histopathology. A multimodality approach that makes use of numerous MRI techniques can lead to significant insights into the nature of the changes in the CNS. MRI-pathology correlation studies in MS are being performed using newer MRI techniques as they become available. Such correlations and basic histopathologic studies have shown abnormalities in MS far beyond the well-documented changes in the plaque and have brought into question the dogma that MS is an initially inflammatory nondegenerative disease. This review briefly outlines technical considerations in MRI-pathology correlative studies and describes the past and current status of our ability to correlate focal and diffuse changes on the MRI with neuropathologic findings in MS patients. PMID:22892523

Moore, G R Wayne; Laule, Cornelia

2012-09-01

310

Multiparametric magnetic resonance imaging in the detection of prostate cancer.  

PubMed

Prostate cancer is the most common malignancy in men, but only about 10% of patients die from that cancer. Recent studies suggest that not all patients benefit from a radical therapeutic approach. When prostate cancer is suspected, magnetic resonance imaging (MRI) can make an important contribution to cancer localization within the prostate. Many studies show that T2-weighted morphologic imaging should be supplemented by multiparametric MRI techniques including diffusion-weighted imaging, contrast-enhanced sequences, and MR spectroscopy. This approach detects aggressive prostate cancer with high sensitivity and specificity. The findings of multiparametric MRI additionally contribute information to the assessment of cancer aggressiveness. The use of these multiparametric MRI techniques will gain an increasing role in the clinical management of prostate cancer patients. They can help in establishing a definitive diagnosis with a minimum of invasiveness and may also contribute to optimal individualized treatment. This review article presents the different techniques of multiparametric MRI and discusses their contribution to the detection of prostate cancer. Moreover, this review outlines an objective approach to image interpretation and structured reporting of MRI findings using the PI-RADS criteria. The review concludes with an outline of approaches to prostate biopsy on the basis of MRI (transrectal ultrasound, direct MRI guidance of tissue sampling, and MRI-ultrasound fusion biopsy) and emerging future uses of MRI in the planning of focal treatment options and in the active surveillance of patients diagnosed with prostate cancer. PMID:24700068

Durmus, T; Baur, A; Hamm, B

2014-03-01

311

Multiparametric magnetic resonance imaging in the detection of prostate cancer.  

PubMed

Prostate cancer is the most common malignancy in men, but only about 10?% of patients die from that cancer. Recent studies suggest that not all patients benefit from a radical therapeutic approach. When prostate cancer is suspected, magnetic resonance imaging (MRI) can make an important contribution to cancer localization within the prostate. Many studies show that T2-weighted morphologic imaging should be supplemented by multiparametric MRI techniques including diffusion-weighted imaging, contrast-enhanced sequences, and MR spectroscopy. This approach detects aggressive prostate cancer with high sensitivity and specificity. The findings of multiparametric MRI additionally contribute information to the assessment of cancer aggressiveness. The use of these multiparametric MRI techniques will gain an increasing role in the clinical management of prostate cancer patients. They can help in establishing a definitive diagnosis with a minimum of invasiveness and may also contribute to optimal individualized treatment. This review article presents the different techniques of multiparametric MRI and discusses their contribution to the detection of prostate cancer. Moreover, this review outlines an objective approach to image interpretation and structured reporting of MRI findings using the PI-RADS criteria. The review concludes with an outline of approaches to prostate biopsy on the basis of MRI (transrectal ultrasound, direct MRI guidance of tissue sampling, and MRI-ultrasound fusion biopsy) and emerging future uses of MRI in the planning of focal treatment options and in the active surveillance of patients diagnosed with prostate cancer. PMID:24452493

Durmus, T; Baur, A; Hamm, B

2014-03-01

312

jSIPRO - analysis tool for magnetic resonance spectroscopic imaging.  

PubMed

Magnetic resonance spectroscopic imaging (MRSI) involves a huge number of spectra to be processed and analyzed. Several tools enabling MRSI data processing have been developed and widely used. However, the processing programs primarily focus on sophisticated spectra processing and offer limited support for the analysis of the calculated spectroscopic maps. In this paper the jSIPRO (java Spectroscopic Imaging PROcessing) program is presented, which is a java-based graphical interface enabling post-processing, viewing, analysis and result reporting of MRSI data. Interactive graphical processing as well as protocol controlled batch processing are available in jSIPRO. jSIPRO does not contain a built-in fitting program. Instead, it makes use of fitting programs from third parties and manages the data flows. Currently, automatic spectra processing using LCModel, TARQUIN and jMRUI programs are supported. Concentration and error values, fitted spectra, metabolite images and various parametric maps can be viewed for each calculated dataset. Metabolite images can be exported in the DICOM format either for archiving purposes or for the use in neurosurgery navigation systems. PMID:23870172

Jiru, Filip; Skoch, Antonin; Wagnerova, Dita; Dezortova, Monika; Hajek, Milan

2013-10-01

313

Active resonant subwavelength grating for scannerless range imaging sensors.  

SciTech Connect

In this late-start LDRD, we will present a design for a wavelength-agile, high-speed modulator that enables a long-term vision for the THz Scannerless Range Imaging (SRI) sensor. It takes the place of the currently-utilized SRI micro-channel plate which is limited to photocathode sensitive wavelengths (primarily in the visible and near-IR regimes). Two of Sandia's successful technologies--subwavelength diffractive optics and THz sources and detectors--are poised to extend the capabilities of the SRI sensor. The goal is to drastically broaden the SRI's sensing waveband--all the way to the THz regime--so the sensor can see through image-obscuring, scattering environments like smoke and dust. Surface properties, such as reflectivity, emissivity, and scattering roughness, vary greatly with the illuminating wavelength. Thus, objects that are difficult to image at the SRI sensor's present near-IR wavelengths may be imaged more easily at the considerably longer THz wavelengths (0.1 to 1mm). The proposed component is an active Resonant Subwavelength Grating (RSG). Sandia invested considerable effort on a passive RSG two years ago, which resulted in a highly-efficient (reflectivity greater than gold), wavelength-specific reflector. For this late-start LDRD proposal, we will transform the passive RSG design into an active laser-line reflector.

Kemme, Shanalyn A.; Nellums, Robert O.; Boye, Robert R.; Peters, David William

2006-11-01

314

Magnetic resonance imaging of microvessels using iron-oxide nanoparticles  

NASA Astrophysics Data System (ADS)

The visualization of microstructures including blood vessels with an inner overall cross-sectional area below approximately 200 ?m remains beyond the capabilities of current clinical imaging modalities. But with magnetic resonance (MR) imaging, magnetic entities cause susceptibility artifacts in the images by disrupting the homogeneous magnetic field in a much larger scale than their actual size. As validated in this paper through simulation and in-vitro experiments, these artifacts can serve as a source of contrast, enabling microvessels with an inner diameter below the spatial resolution of any medical imaging modalities to be visualized using a clinical MR scanner. For such experiments, micron-sized agglomerations of iron-oxide (Fe3O4) nanoparticles were injected in microchannels with internal diameters of 200 and 50 ?m equivalent to a narrower artery or a larger arteriole, and down to a smaller arteriole, respectively. The results show the feasibility of the proposed method for micro-particle detection and the visualization of microvessels using a 1.5 T clinical MR scanner. It was confirmed that the method is reproducible and accurate at the sub-pixel level.

Olamaei, N.; Cheriet, F.; Martel, S.

2013-03-01

315

Magnetic resonance cholangiopancreatography image enhancement for automatic disease detection  

PubMed Central

AIM: To sufficiently improve magnetic resonance cholangiopancreatography (MRCP) quality to enable reliable computer-aided diagnosis (CAD). METHODS: A set of image enhancement strategies that included filters (i.e. Gaussian, median, Wiener and Perona-Malik), wavelets (i.e. contourlet, ridgelet and a non-orthogonal noise compensation implementation), graph-cut approaches using lazy-snapping and Phase Unwrapping MAxflow, and binary thresholding using a fixed threshold and dynamic thresholding via histogram analysis were implemented to overcome the adverse characteristics of MRCP images such as acquisition noise, artifacts, partial volume effect and large inter- and intra-patient image intensity variations, all of which pose problems in application development. Subjective evaluation of several popular pre-processing techniques was undertaken to improve the quality of the 2D MRCP images and enhance the detection of the significant biliary structures within them, with the purpose of biliary disease detection. RESULTS: The results varied as expected since each algorithm capitalized on different characteristics of the images. For denoising, the Perona-Malik and contourlet approaches were found to be the most suitable. In terms of extraction of the significant biliary structures and removal of background, the thresholding approaches performed well. The interactive scheme performed the best, especially by using the strengths of the graph-cut algorithm enhanced by user-friendly lazy-snapping for foreground and background marker selection. CONCLUSION: Tests show promising results for some techniques, but not others, as viable image enhancement modules for automatic CAD systems for biliary and liver diseases. PMID:21160667

Logeswaran, Rajasvaran

2010-01-01

316

Grid Computing Application for Brain Magnetic Resonance Image Processing  

NASA Astrophysics Data System (ADS)

This work emphasizes the use of grid computing and web technology for automatic post-processing of brain magnetic resonance images (MRI) in the context of neuropsychiatric (Alzheimer's disease) research. Post-acquisition image processing is achieved through the interconnection of several individual processes into pipelines. Each process has input and output data ports, options and execution parameters, and performs single tasks such as: a) extracting individual image attributes (e.g. dimensions, orientation, center of mass), b) performing image transformations (e.g. scaling, rotation, skewing, intensity standardization, linear and non-linear registration), c) performing image statistical analyses, and d) producing the necessary quality control images and/or files for user review. The pipelines are built to perform specific sequences of tasks on the alphanumeric data and MRIs contained in our database. The web application is coded in PHP and allows the creation of scripts to create, store and execute pipelines and their instances either on our local cluster or on high-performance computing platforms. To run an instance on an external cluster, the web application opens a communication tunnel through which it copies the necessary files, submits the execution commands and collects the results. We present result on system tests for the processing of a set of 821 brain MRIs from the Alzheimer's Disease Neuroimaging Initiative study via a nonlinear registration pipeline composed of 10 processes. Our results show successful execution on both local and external clusters, and a 4-fold increase in performance if using the external cluster. However, the latter's performance does not scale linearly as queue waiting times and execution overhead increase with the number of tasks to be executed.

Valdivia, F.; Crépeault, B.; Duchesne, S.

2012-02-01

317

Methodological challenges and solutions in auditory functional magnetic resonance imaging  

PubMed Central

Functional magnetic resonance imaging (fMRI) studies involve substantial acoustic noise. This review covers the difficulties posed by such noise for auditory neuroscience, as well as a number of possible solutions that have emerged. Acoustic noise can affect the processing of auditory stimuli by making them inaudible or unintelligible, and can result in reduced sensitivity to auditory activation in auditory cortex. Equally importantly, acoustic noise may also lead to increased listening effort, meaning that even when auditory stimuli are perceived, neural processing may differ from when the same stimuli are presented in quiet. These and other challenges have motivated a number of approaches for collecting auditory fMRI data. Although using a continuous echoplanar imaging (EPI) sequence provides high quality imaging data, these data may also be contaminated by background acoustic noise. Traditional sparse imaging has the advantage of avoiding acoustic noise during stimulus presentation, but at a cost of reduced temporal resolution. Recently, three classes of techniques have been developed to circumvent these limitations. The first is Interleaved Silent Steady State (ISSS) imaging, a variation of sparse imaging that involves collecting multiple volumes following a silent period while maintaining steady-state longitudinal magnetization. The second involves active noise control to limit the impact of acoustic scanner noise. Finally, novel MRI sequences that reduce the amount of acoustic noise produced during fMRI make the use of continuous scanning a more practical option. Together these advances provide unprecedented opportunities for researchers to collect high-quality data of hemodynamic responses to auditory stimuli using fMRI. PMID:25191218

Peelle, Jonathan E.

2014-01-01

318

From Roentgen to magnetic resonance imaging: the history of medical imaging.  

PubMed

Medical imaging has advanced in remarkable ways since the discovery of x-rays 120 years ago. Today's radiologists can image the human body in intricate detail using computed tomography, magnetic resonance imaging, positron emission tomography, ultrasound, and various other modalities. Such technology allows for improved screening, diagnosis, and monitoring of disease, but it also comes with risks. Many imaging modalities expose patients to ionizing radiation, which potentially increases their risk of developing cancer in the future, and imaging may also be associated with possible allergic reactions or risks related to the use of intravenous contrast agents. In addition, the financial costs of imaging are taxing our health care system, and incidental findings can trigger anxiety and further testing. This issue of the NCMJ addresses the pros and cons of medical imaging and discusses in detail the following uses of medical imaging: screening for breast cancer with mammography, screening for osteoporosis and monitoring of bone mineral density with dual-energy x-ray absorptiometry, screening for congenital hip dysplasia in infants with ultrasound, and evaluation of various heart conditions with cardiac imaging. Together, these articles show the challenges that must be met as we seek to harness the power of today's imaging technologies, as well as the potential benefits that can be achieved when these hurdles are overcome. PMID:24663131

Scatliff, James H; Morris, Peter J

2014-01-01

319

Towards simultaneous single emission microscopy and magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

In recent years, the combined nuclear imaging and magnetic resonance imaging (MRI) has drawn extensive research effort. They can provide simultaneously acquired anatomical and functional information inside the human/small animal body in vivo. In this dissertation, the development of an ultrahigh resolution MR-compatible SPECT (Single Photon Emission Computed Tomography) system that can be operated inside a pre-existing clinical MR scanner for simultaneous dual-modality imaging of small animals will be discussed. This system is constructed with 40 small pixel CdTe detector modules assembled in a fully stationary ring SPECT geometry. Series of experiments have demonstrated that this system is capable of providing an imaging resolution of <500?m, when operated inside MR scanners. The ultrahigh resolution MR-compatible SPECT system is built around a small pixel CdTe detector module that we recently developed. Each module consists of CdTe detectors having an overall size of 2.2 cm x 1.1 cm, divided into 64 x 32 pixels of 350 mum in size. A novel hybrid pixel-waveform (HPWF) readout system is also designed to alleviate several challenges for using small-pixel CdTe detectors in ultrahigh-resolution SPECT imaging applications. The HPWF system utilizes a modified version of a 2048-channel 2-D CMOS ASIC to readout the anode pixel, and a digitizing circuitry to sample the signal waveform induced on the cathode. The cathode waveform acquired with the HPWF circuitry offers excellent spatial resolution, energy resolution and depth of interaction (DOI) information, even with the presence of excessive charge-sharing/charge-loss between the small anode pixels. The HPWF CdTe detector is designed and constructed with a minimum amount of ferromagnetic materials, to ensure the MR-compatibility. To achieve sub-500?m imaging resolution, two special designed SPECT apertures have been constructed with different pinhole sizes of 300?m and 500?m respectively. It has 40 pinhole inserts that are made of cast platinum (90%)-iridium (10%) alloy, which provides the maximum stopping power and are compatible with MR scanners. The SPECT system is installed on a non-metal gantry constructed with 3-D printing using nylon powder material. This compact system can work as a "low-cost" desktop ultrahigh resolution SPECT system. It can also be directly operated inside an MR scanner. Accurate system geometrical calibration and corresponding image reconstruction methods for the MRC-SPECT system is developed. In order to account for the magnetic field induced distortion in the SPECT image, a comprehensive charge collection model inside strong magnetic field is adopted to produce high resolution SPECT image inside MR scanner.

Cai, Liang

320

Monitoring water accumulation in a glacier using magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

Tête Rousse is a small polythermal glacier located in the Mont Blanc area (French Alps) at an altitude of 3100 to 3300 m. Recent accumulation of melt water in the glacier was assumed to occur, but such accumulation had yet to be confirmed. Using Surface Nuclear Magnetic Resonance imaging (3-D-SNMR), we showed that the temperate part of the Tête Rousse glacier contains two separate water-filled caverns (central and upper caverns). In 2009, the central cavern contained about 55 000 m3 of water. Since 2010, the cavern is drained every year. Using 3-D-SNMR, we monitored the changes caused by this pumping in the water distribution within the glacier body. Twice a year, we carried out magnetic resonance imaging of the entire glacier and estimated the volume of water accumulated in the central cavern. Our results show the changes in cavern geometry and recharge rate: in two years, the central cavern lost about 73% of its initial volume, but 65% were lost in one year after the first pumping. We also observed that, after being drained, the cavern was recharged at an average rate of 20 to 25 m3 d-1 over the winter months and 120 to 180 m3 d-1 in summer. These observations illustrate how ice and water may refill englacial volume being emptied by artificial draining. Comparison of the 3-D-SNMR results with those obtained by drilling and pumping showed a very good correspondence, confirming the high reliability of 3-D-SNMR imaging.

Legchenko, A.; Vincent, C.; Baltassat, J. M.; Girard, J. F.; Thibert, E.; Gagliardini, O.; Descloitres, M.; Gilbert, A.; Garambois, S.; Chevalier, A.; Guyard, H.

2013-05-01

321

Monitoring water accumulation in a glacier using magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

Tête Rousse is a small polythermal glacier located in the Mont Blanc area (French Alps) at an altitude of 3100 to 3300 m. In 1892, an outburst flood from this glacier released about 200 000 m3 of water mixed with ice, causing much damage. A new accumulation of melt water in the glacier was not excluded. The uncertainty related to such glacier conditions initiated an extensive geophysical study for evaluating the hazard. Using three-dimensional surface nuclear magnetic resonance imaging (3-D-SNMR), we showed that the temperate part of the Tête Rousse glacier contains two separate water-filled caverns (central and upper caverns). In 2009, the central cavern contained about 55 000 m3 of water. Since 2010, the cavern is drained every year. We monitored the changes caused by this pumping in the water distribution within the glacier body. Twice a year, we carried out magnetic resonance imaging of the entire glacier and estimated the volume of water accumulated in the central cavern. Our results show changes in cavern geometry and recharge rate: in two years, the central cavern lost about 73% of its initial volume, but 65% was lost in one year after the first pumping. We also observed that, after being drained, the cavern was recharged at an average rate of 20 to 25 m3 d-1 during the winter months and 120 to 180 m3 d-1 in summer. These observations illustrate how ice, water and air may refill englacial volume being emptied by artificial draining. Comparison of the 3-D-SNMR results with those obtained by drilling and pumping showed a very good correspondence, confirming the high reliability of 3-D-SNMR imaging.

Legchenko, A.; Vincent, C.; Baltassat, J. M.; Girard, J. F.; Thibert, E.; Gagliardini, O.; Descloitres, M.; Gilbert, A.; Garambois, S.; Chevalier, A.; Guyard, H.

2014-01-01

322

Advanced Theory of Driven Birdcage Resonator with Losses for Biomedical Magnetic Resonance Imaging and Spectroscopy  

PubMed Central

A complete time-dependent physics theory of symmetric unperturbed driven Hybrid Birdcage resonator was developed for general application. In particular, the theory can be applied for RF coil engineering, computer simulations of coil-sample interaction, etc. Explicit time dependence is evaluated for different forms of driving voltage. The major steps of the solution development are shown and appropriate explanations are given. Green’s functions and spectral density formula were developed for any form of periodic driving voltage. The concept of distributed power losses based on transmission line theory is developed for evaluation of local losses of a coil. Three major types of power losses are estimated as equivalent series resistances in the circuit of the Birdcage resonator. Values of generated resistances in Legs and End-Rings are estimated. An application of the theory is shown for many practical cases. Experimental curve of B1 field polarization dependence is measured for eight-sections Birdcage coil. It was shown, that the steady-state driven resonance frequencies do not depend on damping factor unlike the free oscillation (transient) frequencies. An equivalent active resistance is generated due to interaction of RF electromagnetic field with a sample. Resistance of the conductor (enhanced by skin effect), Eddy currents and dielectric losses are the major types of losses which contribute to the values of generated resistances. A biomedical sample for magnetic resonance imaging and spectroscopy is the source of the both Eddy current and dielectric losses of a coil. As demonstrated by the theory, Eddy currents losses is the major effect of coil shielding. PMID:20869184

Novikov, Alexander

2010-01-01

323

A prototype manipulator for magnetic resonance-guided interventions inside standard cylindrical magnetic resonance imaging scanners.  

PubMed

The aim of this work is to develop a remotely controlled manipulator to perform minimally invasive diagnostic and therapeutic interventions in the abdominal and thoracic cavities, with real-time magnetic resonance imaging (MRI) guidance inside clinical cylindrical MR scanners. The manipulator is composed of a three degree of freedom Cartesian motion system, which resides outside the gantry of the scanner, and serves as the holder and global positioner of a three degree of freedom arm which extends inside the gantry of the scanner At its distal end, the arm's end-effector can carry an interventional tool such as a biopsy needle, which can be advanced to a desired depth by means of a seventh degree of freedom. These seven degrees of freedom, provided by the entire assembly, offer extended manipulability to the device and a wide envelope of operation to the user, who can select a trajectory suitable for the procedure. The device is constructed of nonmagnetic and nonconductive fiberglass, and carbon fiber composite materials, to minimize artifacts and distortion on the MR images as well as eliminate effects on its operation from the high magnetic field and the fast switching magnetic field gradients used in MR imaging. A user interface was developed for man-in-the-loop control of the device using real-time MR images. The user interface fuses all sensor signals (MR and manipulator information) in a visualization, planning, and control command environment. Path planning is performed with graphical tools for setting the trajectory of insertion of the interventional tool using multislice and/or three dimensional MR images which are refreshed in real time. The device control is performed with an embedded computer which runs real-time control software. The manipulator compatibility with the MR environment and image-guided operation was tested on a 1.5 T MR scanner. PMID:16438235

Tsekos, Nikolaos V; Ozcan, Alpay; Christoforou, Eftychios

2005-11-01

324

COMPRESSED MAGNETIC RESONANCE IMAGING BASED ON WAVELET SPARSITY AND NONLOCAL TOTAL VARIATION  

E-print Network

COMPRESSED MAGNETIC RESONANCE IMAGING BASED ON WAVELET SPARSITY AND NONLOCAL TOTAL VARIATION MR image reconstruction. Index Terms-- Compressive Sensing, MRI, Wavelet Sparsity, Nonlocal Total Variation 1. INTRODUCTION Recent developments in compressive sensing theory[1] show that it is possible

Huang, Junzhou

325

Bacteria tracking by in vivo magnetic resonance imaging  

PubMed Central

Background Different non-invasive real-time imaging techniques have been developed over the last decades to study bacterial pathogenic mechanisms in mouse models by following infections over a time course. In vivo investigations of bacterial infections previously relied mostly on bioluminescence imaging (BLI), which is able to localize metabolically active bacteria, but provides no data on the status of the involved organs in the infected host organism. In this study we established an in vivo imaging platform by magnetic resonance imaging (MRI) for tracking bacteria in mouse models of infection to study infection biology of clinically relevant bacteria. Results We have developed a method to label Gram-positive and Gram-negative bacteria with iron oxide nano particles and detected and pursued these with MRI. The key step for successful labeling was to manipulate the bacterial surface charge by producing electro-competent cells enabling charge interactions between the iron particles and the cell wall. Different particle sizes and coatings were tested for their ability to attach to the cell wall and possible labeling mechanisms were elaborated by comparing Gram-positive and -negative bacterial characteristics. With 5-nm citrate-coated particles an iron load of 0.015 ± 0.002 pg Fe/bacterial cell was achieved for Staphylococcus aureus. In both a subcutaneous and a systemic infection model induced by iron-labeled S. aureus bacteria, high resolution MR images allowed for bacterial tracking and provided information on the morphology of organs and the inflammatory response. Conclusion Labeled with iron oxide particles, in vivo detection of small S. aureus colonies in infection models is feasible by MRI and provides a versatile tool to follow bacterial infections in vivo. The established cell labeling strategy can easily be transferred to other bacterial species and thus provides a conceptual advance in the field of molecular MRI. PMID:23714179

2013-01-01

326

Superparamagnetic nanoparticles for enhanced magnetic resonance and multimodal imaging  

NASA Astrophysics Data System (ADS)

Magnetic resonance imaging (MRI) is a powerful tool for noninvasive tomographic imaging of biological systems with high spatial and temporal resolution. Superparamagnetic (SPM) nanoparticles have emerged as highly effective MR contrast agents due to their biocompatibility, ease of surface modification and magnetic properties. Conventional nanoparticle contrast agents suffer from difficult synthetic reproducibility, polydisperse sizes and weak magnetism. Numerous synthetic techniques and nanoparticle formulations have been developed to overcome these barriers. However, there are still major limitations in the development of new nanoparticle-based probes for MR and multimodal imaging including low signal amplification and absence of biochemical reporters. To address these issues, a set of multimodal (T2/optical) and dual contrast (T1/T2) nanoparticle probes has been developed. Their unique magnetic properties and imaging capabilities were thoroughly explored. An enzyme-activatable contrast agent is currently being developed as an innovative means for early in vivo detection of cancer at the cellular level. Multimodal probes function by combining the strengths of multiple imaging techniques into a single agent. Co-registration of data obtained by multiple imaging modalities validates the data, enhancing its quality and reliability. A series of T2/optical probes were successfully synthesized by attachment of a fluorescent dye to the surface of different types of nanoparticles. The multimodal nanoparticles generated sufficient MR and fluorescence signal to image transplanted islets in vivo. Dual contrast T1/T2 imaging probes were designed to overcome disadvantages inherent in the individual T1 and T2 components. A class of T1/T2 agents was developed consisting of a gadolinium (III) complex (DTPA chelate or DO3A macrocycle) conjugated to a biocompatible silica-coated metal oxide nanoparticle through a disulfide linker. The disulfide linker has the ability to be reduced in vivo by glutathione, releasing large payloads of signal-enhancing T1 probes into the surrounding environment. Optimization of the agent occurred over three sequential generations, with each generation addressing a new challenge. The result was a T2 nanoparticle containing high levels of conjugated T1 complex demonstrating enhanced MR relaxation properties. The probes created here have the potential to play a key role in the advancement of nanoparticle-based agents in biomedical MRI applications.

Sikma, Elise Ann Schultz

327

Magnetic resonance pore imaging, a tool for porous media research  

NASA Astrophysics Data System (ADS)

The internal structure of porous materials is of importance in many areas such as medicine, chemical engineering, and petrophysics. While diffraction methods such as x ray are widely used to study the internal pore space, these methods suffer from the loss of the phase information in the detected signals. Recently, an advanced diffusive diffraction NMR method was proposed [F. B. Laun , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.107.048102 107, 048102 (2011)] which is predicted to preserve the phase information, thus overcoming this severe limitation of diffraction methods in general. Here we provide experimental confirmation that the suggested approach is indeed able to acquire the diffractive signal including its phase which allows the direct image reconstruction of the pore space, averaged over all pores. We furthermore prove that this approach may combine the advantages of magnetic resonance imaging, namely, its robust and straightforward image reconstruction via a Fourier transformation with the much improved spatial resolution of pulsed gradient spin echo NMR.

Hertel, Stefan; Hunter, Mark; Galvosas, Petrik

2013-03-01

328

Tumor growth and its effect on Magnetic Resonance Imaging signal  

NASA Astrophysics Data System (ADS)

The goal of this project is twofold. On one hand, we have developed computer code based on simple probabilistic rules to model the growth (or shrinking) of cancerigenous tissue. We assume that initially there exists a differentiated cell, which has a time- dependent probability of reproducing. If it did reproduce, then we assume that it has a finite probability of dying before reproducing again. This simple model falls into the Eden-type kind, and presents appropriate bulk growth characteristics, as it follows Gompert observational law. We propose new methods of geometrical characterization of the tumor. Besides its total mass, we also consider higher multipolar order of mass distribution and surface fractal dimension. In addition, we study how the geometrical properties of the tumor affect the Magnetic Resonance Imaging (MRI) signal. To this end, we consider a human brain in the presence of radiofrequency fields. We calculate the MRI image of this object. Then, we introduce a tumor in the white-gray matter region and reobtain the MRI image. We associate the signal changes with the geometrical properties of the tumor.

Cersosimo, Homero; Colon, Jorge; Ramos, Elio; Zypman, Fredy

2000-03-01

329

Simultaneous Electroencephalography and Functional Magnetic Resonance Imaging of General Anesthesia  

PubMed Central

It has been long appreciated that anesthetic drugs induce stereotyped changes in electroencephalogram (EEG), but the relationships between EEG and underlying brain function remain poorly understood. Functional imaging methods including positron emission tomography (PET) and functional magnetic resonance imaging (fMRI), have become important tools for studying how anesthetic drugs act in the human brain to induce the state of general anesthesia. To date, no investigation has combined functional MRI with EEG to study general anesthesia. We report here a paradigm for conducting combined fMRI and EEG studies of human subjects under general anesthesia. We discuss the several technical and safety problems that must be solved to undertake this type of multimodal functional imaging and show combined recordings from a human subject. Combined fMRI and EEG exploits simultaneously the high spatial resolution of fMRI and the high temporal resolution of EEG. In addition, combined fMRI and EEG offers a direct way to relate established EEG patterns induced by general anesthesia to changes neural activity in specific brain regions as measured by changes in fMRI blood oxygen level dependent (BOLD) signals. PMID:19351356

Purdon, Patrick L.; Pierce, Eric T.; Bonmassar, Giorgio; Walsh, John; Harrell, P. Grace; Kwo, Jean; Deschler, Daniel; Barlow, Margaret; Merhar, Rebecca C.; Lamus, Camilo; Mullaly, Catherine M.; Sullivan, Mary; Maginnis, Sharon; Skoniecki, Debra; Higgins, Helen-Anne; Brown, Emery N.

2009-01-01

330

Magnetic resonance imaging in patients with congenital heart disease.  

PubMed

Magnetic resonance imaging (MRI) was conducted with use of the spin-echo technique (0.35 Tesla) in 22 patients with a variety of congenital and cardiovascular anomalies and in 16 normal volunteers. Electrocardiographic (ECG) synchronization of the data acquisition produced transverse, parasagittal, and coronal tomograms that were used to define size and relationship of the great vessels and internal cardiac structures. MRI findings were corroborated by angiography and sector-scan echocardiography. In most patients the diagnosis had been established before the MRI study. MRI detected all of 11 abnormalities at the level of the great vessels, all of six atrial septal abnormalities, and 10 of 11 ventricular septal defects. Images of poor quality resulting from patient motion were obtained in the one instance in which a small ventricular septal defect was not imaged. Of two patients with Ebstein's anomaly, the displacement of the tricuspid leaflets was shown in one patient but was not evident in another. Complex anomalies such as double-outlet right ventricle, uncorrected L-transposition, single atrioventricular valve, single ventricle, and common ventricle were clearly shown by MRI. Initial experience with MRI has indicated the effectiveness of this technique for defining great vessel and internal cardiac anatomy in patients with congenital heart disease. This is accomplished without the use of contrast media and is thus a completely noninvasive technique for cardiovascular diagnosis. PMID:6488498

Higgins, C B; Byrd, B F; Farmer, D W; Osaki, L; Silverman, N H; Cheitlin, M D

1984-11-01

331

Magnetic resonance imaging of inflammatory arthropathies of peripheral joints.  

PubMed

As the treatment of inflammatory arthropathies has advanced with new therapies that can slow or even halt the development of disabling disease, early and accurate diagnosis has become imperative. Magnetic resonance (MR) imaging has proved to be very sensitive in the detection of erosions, but more importantly, it can demonstrate pre-erosive changes. Detection of synovitis and edema-like bone marrow lesions for initial diagnosis and as an indicator of disease progression can provide crucial information leading to therapeutic interventions before permanent joint damage occurs. Understanding the characteristic intra-articular and extra-articular MR imaging findings of the inflammatory arthritides allows the radiologist to provide appropriate consultations in the care of these patients. The MR appearances of both intra-articular and extra-articular findings of inflammatory arthritis are presented. Despite the advances in imaging, however, many of the MR findings remain nonspecific, and radiologists must avoid overdiagnosis by synthesizing all of the clinical information available into their interpretations. PMID:22648080

Forney, Michael C; Winalski, Carl S; Schils, Jean P

2011-04-01

332

A magnetic-resonance-imaging-compatible remote catheter navigation system.  

PubMed

A remote catheter navigation system compatible with magnetic resonance imaging (MRI) has been developed to facilitate MRI-guided catheterization procedures. The interventionalist's conventional motions (axial motion and rotation) on an input catheter - acting as the master - are measured by a pair of optical encoders, and a custom embedded system relays the motions to a pair of ultrasonic motors. The ultrasonic motors drive the patient catheter (slave) within the MRI scanner, replicating the motion of the input catheter. The performance of the remote catheter navigation system was evaluated in terms of accuracy and delay of motion replication outside and within the bore of the magnet. While inside the scanner bore, motion accuracy was characterized during the acquisition of frequently used imaging sequences, including real-time gradient echo. The effect of the catheter navigation system on image signal-to-noise ratio (SNR) was also evaluated. The results show that the master-slave system has a maximum time delay of 41 ± 21 ms in replicating motion; an absolute value error of 2 ± 2° was measured for radial catheter motion replication over 360° and 1.0 ± 0.8 mm in axial catheter motion replication over 100 mm of travel. The worst-case SNR drop was observed to be 2.5%. PMID:23192485

Tavallaei, Mohammad Ali; Thakur, Yogesh; Haider, Syed; Drangova, Maria

2013-04-01

333

Fusion of color Doppler and magnetic resonance images of the heart.  

PubMed

This study was designed to establish and analyze color Doppler and magnetic resonance fusion images of the heart, an approach for simultaneous testing of cardiac pathological alterations, performance, and hemodynamics. Ten volunteers were tested in this study. The echocardiographic images were produced by Philips IE33 system and the magnetic resonance images were generated from Philips 3.0-T system. The fusion application was implemented on MATLAB platform utilizing image processing technology. The fusion image was generated from the following steps: (1) color Doppler blood flow segmentation, (2) image registration of color Doppler and magnetic resonance imaging, and (3) image fusion of different image types. The fusion images of color Doppler blood flow and magnetic resonance images were implemented by MATLAB programming in our laboratory. Images and videos were displayed and saved as AVI and JPG. The present study shows that the method we have developed can be used to fuse color flow Doppler and magnetic resonance images of the heart. We believe that the method has the potential to: fill in information missing from the ultrasound or MRI alone, show structures outside the field of view of the ultrasound through MR imaging, and obtain complementary information through the fusion of the two imaging methods (structure from MRI and function from ultrasound). PMID:21656081

Wang, Chao; Chen, Ming; Zhao, Jiang-Min; Liu, Yi

2011-12-01

334

Imaging of transplanted islets by positron emission tomography, magnetic resonance imaging, and ultrasonography  

PubMed Central

While islet transplantation is considered a useful therapeutic option for severe diabetes mellitus (DM), the outcome of this treatment remains unsatisfactory. This is largely due to the damage and loss of islets in the early transplant stage. Thus, it is important to monitor the condition of the transplanted islets, so that a treatment can be selected to rescue the islets from damage if needed. Recently, numerous trials have been performed to investigate the efficacy of different imaging modalities for visualizing transplanted islets. Positron emission tomography (PET) and magnetic resonance imaging (MRI) are the most commonly used imaging modalities for this purpose. Some groups, including ours, have also tried to visualize transplanted islets by ultrasonography (US). In this review article, we discuss the recent progress in islet imaging. PMID:24231367

Sakata, Naoaki; Yoshimatsu, Gumpei; Tsuchiya, Haruyuki; Aoki, Takeshi; Mizuma, Masamichi; Motoi, Fuyuhiko; Katayose, Yu; Kodama, Tetsuya; Egawa, Shinichi; Unno, Michiaki

2013-01-01

335

Concurrent multiscale imaging with magnetic resonance imaging and optical coherence tomography  

PubMed Central

Abstract. We develop a novel platform based on a tele-operated robot to perform high-resolution optical coherence tomography (OCT) imaging under continuous large field-of-view magnetic resonance imaging (MRI) guidance. Intra-operative MRI (iMRI) is a promising guidance tool for high-precision surgery, but it may not have sufficient resolution or contrast to visualize certain small targets. To address these limitations, we develop an MRI-compatible OCT needle probe, which is capable of providing microscale tissue architecture in conjunction with macroscale MRI tissue morphology in real time. Coregistered MRI/OCT images on ex vivo chicken breast and human brain tissues demonstrate that the complementary imaging scales and contrast mechanisms have great potential to improve the efficiency and the accuracy of iMRI procedure. PMID:23609326

Liang, Chia-Pin; Yang, Bo; Kim, Il Kyoon; Makris, George; Desai, Jaydev P.; Gullapalli, Rao P.; Chen, Yu

2013-01-01

336

Concurrent multiscale imaging with magnetic resonance imaging and optical coherence tomography  

PubMed Central

Abstract. We develop a novel platform based on a tele-operated robot to perform high-resolution optical coherence tomography (OCT) imaging under continuous large field-of-view magnetic resonance imaging (MRI) guidance. Intra-operative MRI (iMRI) is a promising guidance tool for high-precision surgery, but it may not have sufficient resolution or contrast to visualize certain small targets. To address these limitations, we develop an MRI-compatible OCT needle probe, which is capable of providing microscale tissue architecture in conjunction with macroscale MRI tissue morphology in real time. Coregistered MRI/OCT images on ex vivo chicken breast and human brain tissues demonstrate that the complementary imaging scales and contrast mechanisms have great potential to improve the efficiency and the accuracy of iMRI procedure.

Liang, Chia-Pin; Yang, Bo; Kim, Il Kyoon; Makris, George; Desai, Jaydev P.; Gullapalli, Rao P.; Chen, Yu

2013-01-01

337

Imaging Atherosclerosis with Hybrid Positron Emission Tomography/Magnetic Resonance Imaging  

PubMed Central

Noninvasive imaging of atherosclerosis could potentially move patient management towards individualized triage, treatment, and followup. The newly introduced combined positron emission tomography (PET) and magnetic resonance imaging (MRI) system could emerge as a key player in this context. Both PET and MRI have previously been used for imaging plaque morphology and function: however, the combination of the two methods may offer new synergistic opportunities. Here, we will give a short summary of current relevant clinical applications of PET and MRI in the setting of atherosclerosis. Additionally, our initial experiences with simultaneous PET/MRI for atherosclerosis imaging are presented. Finally, future potential vascular applications exploiting the unique combination of PET and MRI will be discussed.

Kjær, Andreas

2015-01-01

338

Assessment of gray matter heterotopia by magnetic resonance imaging  

PubMed Central

AIM: To evaluate magnetic resonance imaging (MRI) features of different types of gray matter heterotopia. METHODS: Between June 2005 and December 2009, the medical records and MRI studies of patients with gray matter heterotopia were reviewed. The MRI morphologic findings of heterotopia were recorded along with the presence and type of associated cranial malformations. Available clinical and electrophysiological data were also recorded. RESULTS: 20 patients were included in the study. Their ages ranged from 9 mo to 39 years with a mean age of 15 years. All patients suffered from epileptic seizures. According to the location of heterotopia, patients were classified into three groups: subependymal (12), subcortical (5) and band (3) heterotopia. CONCLUSION: MRI was useful in diagnosing and differentiating between various types of gray matter heterotopia. The severity of clinical manifestations of heterotopia was related to the location and pattern of heterotopia. Determination of heterotopia type and its extent is useful for management planning and predicting prognosis. PMID:22468189

Donkol, Ragab H; Moghazy, Khaled M; Abolenin, Alaeddin

2012-01-01

339

Combining functional magnetic resonance imaging with transcranial electrical stimulation  

PubMed Central

Transcranial electrical stimulation (tES) is a neuromodulatory method with promising potential for basic research and as a therapeutic tool. The most explored type of tES is transcranial direct current stimulation (tDCS), but also transcranial alternating current stimulation (tACS) and transcranial random noise stimulation (tRNS) have been shown to affect cortical excitability, behavioral performance and brain activity. Although providing indirect measure of brain activity, functional magnetic resonance imaging (fMRI) can tell us more about the global effects of stimulation in the whole brain and what is more, on how it modulates functional interactions between brain regions, complementing what is known from electrophysiological methods such as measurement of motor evoked potentials. With this review, we aim to present the studies that have combined these techniques, the current approaches and discuss the results obtained so far. PMID:23935578

Saiote, Catarina; Turi, Zsolt; Paulus, Walter; Antal, Andrea

2013-01-01

340

Magnetic resonance imaging in the evaluation of the brainstem  

SciTech Connect

Magnetic resonance (MR) images of the brainstem region from 100 normal or asymptomatic individuals were reviewed in addition to those of 17 patients with intra-axial brainstem lesions and 15 patients with extra-axial masses around the brainstem. MR was able to demonstrate consistently the normal anatomy of the brainstem and adjacent cisterns, though the distinction between gray and white matter was seldom possible with the present technology. Masses in and around the brainstem were all accurately identified on MR and its sensitivity was superior to that of x-ray computed tomography (CT). These study results show that despite its technical limitations, MR is presently the examination of choice for the evaluation of brainstem abnormalities and eventually it will undoubtedly replace metrizamide CT cisternography.

Han, J.S.; Bonstelle, C.T.; Kaufman, B.; Benson, J.E.; Alfidi, R.J.; Clampitt, M.; Van Dyke, C.; Huss, R.G.

1984-03-01

341

Hybrid microparticles for drug delivery and magnetic resonance imaging.  

PubMed

In this work, we report the synthesis, characterization, and possible application as drug-delivery system magnetically triggered, of hybrid microparticles formed by magnetic nanoparticles embedded within poly(?-caprolactone). The magnetism of the microparticles permits their localization within the body using magnetic resonance imaging, and the biodegradable polymer layer allows entrapping drugs that can be released when temperature increases. The synthesis of the hybrid material was performed using "grafting from" technique of conveniently modified magnetic nanoparticles. Subsequently, the resulting hybrid nanoparticles were assembled into spherical particles of 138 ± 49 nm via precipitation technique. The produced hybrid material was evaluated as stimuli-responsive drug delivery system in which the release of the drug was triggered by magnetic induction. Furthermore, the microparticles were injected in rats and their localization within the animal was monitored using the local field inhomogeneities generated by the particles. PMID:22915497

Serrano-Ruiz, David; Laurenti, Marco; Ruiz-Cabello, Jesús; López-Cabarcos, Enrique; Rubio-Retama, Jorge

2013-05-01

342

Surface plasmon resonance imaging biosensor based on silicon photodiode array  

NASA Astrophysics Data System (ADS)

The detection limit of surface plasmon resonance imaging (SPRI) biosensor is constrained in part by the SPR biochip and in part by the resolution of the optical intensity of detecting instruments. In this paper, silicon photodiode is proposed as the optical intensity detecting element instead of the traditionally used charge coupled device (CCD), combining with high resolution analog/digital converter, this method can efficiently reduce the cost and increase the sensitivity of the SPRI system while keeping its virtue of multiple channels real time detecting. Based on this method, An SPRI experimental system with two channels is designed and the optical intensity of each channel is detected by a photodiode. By carrying out testing experiments using sucrose solution with different concentrations (corresponding to different refractive index), the system sensitivity of 10-6 refractive index unit (RIU) is obtained.

Yin, Shaoyun; Sun, Xiuhui; Deng, Qiling; Xia, Liangping; Du, Chunlei

2010-11-01

343

Multimodality magnetic resonance imaging in hepatic encephalopathy: an update.  

PubMed

Hepatic encephalopathy (HE) is a neuropsychiatric complication of cirrhosis or acute liver failure. Currently, HE is regarded as a continuous cognitive impairment ranging from the mildest stage, minimal HE to overt HE. Hyperammonaemia and neuroinflammation are two main underlying factors which contribute to the neurological alterations in HE. Both structural and functional impairments are found in the white mater and grey mater involved in HE. Although the investigations into HE pathophysiological mechanism are enormous, the exact pathophysiological causes underlying HE remain controversial. Multimodality magnetic resonance imaging (MRI) plays an important role in helping to understand the pathological process of HE. This paper reviews the up-to-date multimodality MRI methods and predominant findings in HE patients with a highlight of the increasingly important role of blood oxygen level dependent functional MRI. PMID:25170210

Zhang, Xiao-Dong; Zhang, Long-Jiang; Wu, Sheng-Yong; Lu, Guang-Ming

2014-08-28

344

Magnetic resonance imaging of abdominal aortic aneurysms. [Aneurysm  

SciTech Connect

Magnetic resonance imaging (MRI) was performed in 20 patients with radiologically or surgically proven abdominal aortic aneurysms using a Siemens Magnetom scanner with a 0.35-T superconductive magnet. Of nine patients who underwent surgical repair, MRI correctly demonstrated the origin of the aortic aneurysm in nine and accurately determined the status of the iliac arteries in eight. Of 11 patients who did not have surgical repair, MRI findings correlated well with other radiologic studies. MRI was found to be more reliable than sonography in determining the relation between the aneurysm and the renal arteries as well as the status of the iliac arteries. Despite these advantages, the authors still advocate sonography as the screening procedure of choice in patients with suspected abdominal aortic aneurysms because of its lower cost and ease of performance. MRI should be reserved for patients who have had unsuccessful or equivocal sonographic examinations.

Lee, J.K.T.; Ling, D.; Heiken, J.P.; Glazer, H.S.; Sicard, G.A.; Totty, W.G.; Levitt, R.G.; Murphy, W.A.

1984-12-01

345

In vivo Magnetic Resonance Imaging of Tumor Protease Activity  

PubMed Central

Increased expression of cathepsins has diagnostic as well as prognostic value in several types of cancer. Here, we demonstrate a novel magnetic resonance imaging (MRI) method, which uses poly-L-glutamate (PLG) as an MRI probe to map cathepsin expression in vivo, in a rat brain tumor model. This noninvasive, high-resolution and non-radioactive method exploits the differences in the CEST signals of PLG in the native form and cathepsin mediated cleaved form. The method was validated in phantoms with known physiological concentrations, in tumor cells and in an animal model of brain tumor along with immunohistochemical analysis. Potential applications in tumor diagnosis and evaluation of therapeutic response are outlined. PMID:25124082

Haris, Mohammad; Singh, Anup; Mohammed, Imran; Ittyerah, Ranjit; Nath, Kavindra; Nanga, Ravi Prakash Reddy; Debrosse, Catherine; Kogan, Feliks; Cai, Kejia; Poptani, Harish; Reddy, Damodar; Hariharan, Hari; Reddy, Ravinder

2014-01-01

346

Multimodality magnetic resonance imaging in hepatic encephalopathy: An update  

PubMed Central

Hepatic encephalopathy (HE) is a neuropsychiatric complication of cirrhosis or acute liver failure. Currently, HE is regarded as a continuous cognitive impairment ranging from the mildest stage, minimal HE to overt HE. Hyperammonaemia and neuroinflammation are two main underlying factors which contribute to the neurological alterations in HE. Both structural and functional impairments are found in the white mater and grey mater involved in HE. Although the investigations into HE pathophysiological mechanism are enormous, the exact pathophysiological causes underlying HE remain controversial. Multimodality magnetic resonance imaging (MRI) plays an important role in helping to understand the pathological process of HE. This paper reviews the up-to-date multimodality MRI methods and predominant findings in HE patients with a highlight of the increasingly important role of blood oxygen level dependent functional MRI. PMID:25170210

Zhang, Xiao-Dong; Zhang, Long-Jiang; Wu, Sheng-Yong; Lu, Guang-Ming

2014-01-01

347

Nanostructured surfaces for surface plasmon resonance spectroscopy and imaging  

NASA Astrophysics Data System (ADS)

Surface plasmon resonance (SPR) has achieved widespread recognition as a sensitive, label-free, and versatile optical method for monitoring changes in refractive index at a metal-dielectric interface. Refractive index deviations of 10-6 RIU are resolvable using SPR, and the method can be used in real-time or ex-situ. Instruments based on carboxymethyl dextran coated SPR chips have achieved commercial success in biological detection, while SPR sensors can also be found in other fields as varied as food safety and gas sensing. Chapter 1 provides a physical background of SPR sensing. A brief history of the technology is presented, and publication data are included that demonstrate the large and growing interest in surface plasmons. Numerous applications of SPR sensors are listed to illustrate the broad appeal of the method. Surface plasmons (SPs) and surface plasmon polaritions (SPPs) are formally defined, and important parameters governing their spatial behavior are derived from Maxwell's equations and appropriate boundary conditions. Physical requirements for exciting SPs with incident light are discussed, and SPR imaging is used to illustrate the operating principle of SPR-based detection. Angle-tunable surface enhanced infrared absorption (SEIRA) of polymer vibrational modes via grating-coupled SPR is demonstrated in Chapter 2. Over 10-fold enhancement of C-H stretching modes was found relative to the absorbance of the same film in the absence of plasmon excitation. Modeling results are used to support and explain experimental observations. Improvements to the grating coupler SEIRA platform in Chapter 2 are explored in Chapters 3 and 4. Chapter 3 displays data for two sets of multipitch gratings: one set with broadly distributed resonances with the potential for multiband IR enhancement and the other with finely spaced, overlapping resonances to form a broadband IR enhancement device. Diffraction gratings having multiple periods were fabricated using a Lloyd's mirror interferometer to perform multiple exposures at multiple angles before developing. Precise control of the resonance position is shown by locating three SPR dips at predetermined wavenumbers of 5000, 4000, and 3000 cm-1, respectively. A set of three gratings, each having four closely spaced resonances is employed to show how the sensor response could be broadened. The work in Chapter 3 shows potential for simultaneous enhancement of multiple vibrational modes; the multiband approach might find application for modes at disparate locations within the IR spectrum, while the broadband approach may allow concurrent probing of broad single modes or clusters of narrow modes within a particular neighborhood of the spectrum. Chapter 4 uses the rigorous coupled-wave analysis (RCWA) method to numerically explore another facet of the nanostructure-based tunability of grating-baed SPR sensing. The work in this chapter illustrates how infrared signal enhancement could be tailored by through adjustment of the grating amplitude. Modeled infrared reflection absorption (IRRAS) spectra and electric field distributions were generated for several nanostructured grating configurations. It was found that there exists a critical amplitude value for a given grating pitch where the plasmon response achieves a maximum. Amplitudes greater than this critical value produce a broader and attenuated plasmon peak, while smaller amplitudes produce a plasmon resonance that is not as intense. Field simulations show how amplitudes nearer the critical amplitude resulted in large increases in the electric field within an analyte film atop the sensor surface, and the relative strength of the increased field is predictable based on the appearance of the IRRAS spectra. It is believed that these larger fields are the cause of observed enhanced absorption. Published reports pertaining to interactions of SPs with molecular resonance and to diffraction-based tracking of plasmons without a spectrometer are included in the Appendix to this thesis. In the first of the two reports, it is shown that plasmons

Petefish, Joseph W.

348

An Efficient Region of Interest Acquisition Method for Dynamic Magnetic Resonance Imaging  

E-print Network

techniques use a series of magnetic field gradients and radio-frequency (rf) pulses to encode the positionAn Efficient Region of Interest Acquisition Method for Dynamic Magnetic Resonance Imaging William-- Motivated by recent work in the area of dy- namic magnetic resonance imaging (MRI), we develop a new

Banks, David

349

Recalcitrant Patellar TendinitisMagnetic Resonance Imaging, Histologic Evaluation, and Surgical Treatment  

Microsoft Academic Search

Magnetic resonance imaging findings and the results of surgical treatment and histologic evaluation of 11 knees in 9 athletes with recalcitrant patellar tendinitis are reported. All of the athletes had no improvement with traditional nonoperative treatment and all had ab normal magnetic resonance imaging findings consis tent with chronic patellar tendinitis. Surgical exploration and debridement were performed on the 11

James E. Popp; Joseph S. Yu; Christopher C. Kaeding

1997-01-01

350

A NEW METHOD FOR FIBER TRACTOGRAPHY IN DIFFUSION TENSOR MAGNETIC RESONANCE IMAGES  

E-print Network

A NEW METHOD FOR FIBER TRACTOGRAPHY IN DIFFUSION TENSOR MAGNETIC RESONANCE IMAGES L. M. San,marcma,caralb}@tel.uva.es ABSTRACT This paper deals with the development of a new fiber tracking algorithm to be used with high resolution diffusion tensor fields acquired via magnetic resonance imaging. The tracking of white matter

351

Brain Natriuretic Peptide and Magnetic Resonance Imaging in Tetralogy With Right Ventricular Dilatation  

Microsoft Academic Search

Background. Cardiac volumetry by magnetic resonance imaging can guide the timing for reoperation in mini- mally symptomatic or asymptomatic patients with pul- monary insufficiency after corrected tetralogy of Fallot. Pro-brain natriuretic peptide (BNP) is a marker of ven- tricular dysfunction and wall stress, and levels may complement magnetic resonance imaging in cardiac as- sessment before and after pulmonary valve replacement.

Ali Dodge-Khatami; Emanuela Valsangiacomo Büchel; Walter Knirsch; Alexander Kadner; Valentin Rousson; Hitendu H. Dave; Urs Bauersfeld; René Prêtre

2010-01-01

352

Brain Activation in Parkinson's Disease during a Functional Magnetic Resonance Imaging Set Shifting Task: Preliminary Findings  

E-print Network

Brain Activation in Parkinson's Disease during a Functional Magnetic Resonance Imaging Set Shifting with Parkinson's disease (PD) and age-matched controls using event-related functional magnetic resonance imaging (fMRI). Cognitive impairment is a common non-motor manifestation of Parkinson's disease (PD

Lichtarge, Olivier

353

Noninvasive assessment of the injured human spinal cord by means of functional magnetic resonance imaging  

Microsoft Academic Search

Study design: A magnetic resonance imaging technique that enables indirect detection of neuronal activity has been developed for the spinal cord. In the present study, this method, spinal functional magnetic resonance imaging (fMRI), is applied to the first study of the injured spinal cord, with the goal of better clinical assessment of the entire cord.Objectives: The objectives of this project

P W Stroman; J Kornelsen; A Bergman; V Krause; K Ethans; K L Malisza; B Tomanek

2004-01-01

354

Magnet driver for producing ultra-high gradient magnetic fields for magnetic resonance imaging  

Microsoft Academic Search

Pulsed gradient magnetic fields are required for magnetic resonance imaging (MRI). Many imaging sequences (e.g., echo planar imaging, diffusion tensor imaging) could be improved with shorter gradient pulses. MRI systems currently available typically require ramp times of hundreds of microseconds. The goal of the work described here is to achieve very high gradient fields, with very short rise times to

Howard D. Sanders; Steven C. Glidden; Daniel M. Warnow; Irving N. Weinberg; Pavel Stepanov; Roland Probst; Alan McMillan; Rao Gullapalli; Piotr M. Starewicz; William F. B. Punchard; Kai-Ming Lo; Stanley Thomas Fricke

2011-01-01

355

[Diagnosis of atrial septal defect using magnetic resonance imaging].  

PubMed

We studied the morphological features of defects of the interatrial septum using magnetic resonance imaging (MRI) to determine the sizes of defects and other abnormalities. MR images were obtained in 28 patients with atrial septal defect, including five cases with complicated anomalies (two with Ebstein's anomaly, one pentalogy of Fallot, and one anomalous pulmonary vein connection and azygos continuation). Images were also obtained in the control subjects including seven normal volunteers and 142 patients with various acquired heart diseases. The diagnosis of atrial septal defect was established by cardiac catheterization, angiography and two-dimensional echocardiography prior to the MRI studies, and in 14 patients, the diagnosis was confirmed by surgery. The MRI unit had a superconducting magnet and operated at 0.25 or 0.50 Tesla. A spin echo pulse sequence was used with an echo time of 40 or 60 msec. At the beginning of this study, non-gated MRI images were obtained in the 28 controls and in three patients with atrial septal defect. Nongated MRI could not image the anatomical structure of the interatrial septa of 12 of the 28 controls, or any of the three patients with atrial septal defect. Nongated MRI was, therefore, inadequate for visualizing cardiac anatomy. Gated MRI images were obtained in 141 controls and in 25 patients with atrial septal defect. Gated MRI revealed the interatrial septum, interventricular septum, atrioventricular septum, mitral valve, tricuspid valve and other intracardiac structures in most subjects. In 17 control subjects (12%), however, there was a very faint signal from the central portion of the interatrial septum. In these instances, there was a gradual fading of the signal of the interatrial septum, so that they could be distinguished from the atrial septal defect. The sudden disappearance of the signal from the interatrial septum was observed by gated MRI in all 25 patients with atrial septal defect. The sizes of the defects by MRI coincided with the findings at surgery in all 14 patients. MRI showed right atrial dilatation, right ventricular hypertrophy and dilatation, and pulmonary artery dilatation in most of the patients having atrial septal defect. Complex anomalies associated with atrial septal defect were also clearly shown by MRI, such as displacement of the tricuspid leaflets in two patients with Ebstein's anomaly, and anomalous pulmonary venous connection and persistent left superior vena cava in one patient. These results indicated that gated MRI is a valuable noninvasive method of diagnosing atrial septal defect and complicating anomalies. PMID:3506607

Sakakibara, M; Kobayashi, S; Imai, H; Watanabe, S; Masuda, Y; Inagaki, Y

1987-12-01

356

Application of Advanced Magnetic Resonance Imaging Techniques in Evaluation of the Lower Extremity  

PubMed Central

Synopsis This article reviews current magnetic resonance imaging techniques for imaging the lower extremity, focusing on imaging of the knee, ankle, and hip joints. Recent advancements in MRI include imaging at 7 Tesla, using multiple receiver channels, T2* imaging, and metal suppression techniques, allowing more detailed visualization of complex anatomy, evaluation of morphological changes within articular cartilage, and imaging around orthopedic hardware. PMID:23622097

Braun, Hillary J.; Dragoo, Jason L.; Hargreaves, Brian A.; Levenston, Marc E.; Gold, Garry E.

2012-01-01

357

Fetal imaging by nuclear magnetic resonance: a study in goats: work in progress  

SciTech Connect

Nuclear magnetic resonance proton imaging was used to obtain images of goat fetuses in utero. The long T1 relaxation time of amniotic fluid makes it appear black on proton density images when examined using the Aberdeen imager, and so allows very good discrimination of the position and structure of the fetus. Some fetal internal tissues can be seen on T1 images. These findings suggest that NMR imaging has great potential in pregnancy studies.

Foster, M.A. (Univ. of Aberdeen, Scotland); Knight, C.H.; Rimmington, J.E.; Mallard, J.R.

1983-10-01

358

Magnetic Resonance Imaging of Tissues Compatible with Supernumerary Extraocular Muscles  

PubMed Central

PURPOSE To determine by magnetic resonance imaging (MRI) the prevalence and anatomy of anomalous EOM bands. DESIGN Prospective, observational case series. METHODS High resolution, multi-positional, surface coil orbital MRI was performed using T1 or T2 fast spin echo weighting with target fixation control under a prospective protocol in normal adult subjects and a diverse group of strabismic patients between 1996 and 2009. Images demonstrating anomalous EOM bands were analyzed digitally to evaluate their sizes and paths, correlating findings with complete ophthalmic and motility examinations. RESULTS Among 118 orthotropic and 453 strabismic subjects, one (0.8%) orthotropic and 11 (2.4%) strabismic subjects exhibited unilateral or bilateral orbital bands having MRI signal characteristics identical to EOM. Most bands occurred without other EOM dysplasia and coursed in the retrobulbar space between rectus EOMs such as medial (MR) to lateral rectus (LR), or superior (SR) to inferior rectus (IR), or from one EOM to the globe. In two cases, horizontal bands from MR to LR immediately posterior to the globe apparently limited supraduction by collision with the optic nerve. All bands were too deep to be approached via conventional strabismus surgical approaches. CONCLUSIONS About 2% of humans exhibit on MRI deep orbital bands consistent with supernumerary EOMs. While band anatomy is non-oculorotary, some bands may cause restrictive strabismus. PMID:20801423

Khitri, Monica R.; Demer, Joseph L.

2010-01-01

359

Magnetic resonance imaging of the female pelvis: initial experience  

SciTech Connect

The potential of magnetic resonance imaging (MRI) was evaluated in 21 female subjects: seven volunteers, 12 patients scanned for reasons unrelated to the lower genitourinary tract, and two patients referred with gynecologic disease. The uterus at several stages was examined; the premenarcheal uterus (one patient), the uterus of reproductive age (12 patients), the postmenopausal uterus (two patients), and in an 8 week pregnancy (one patient). The myometrium and cyclic endometrium in the reproductive age separated by a low-intensity line (probably stratum basale), which allows recognition of changes in thickness of the cyclic endometrium during the menstrual cycle. The corpus uteri can be distinguished from the cervix by the transitional zone of the isthmus. The anatomic relation of the uterus to bladder and rectum is easily outlined. The vagina can be distinguished from the cervix, and the anatomic display of the closely apposed bladder, vagina, and rectum is clear on axial and coronal images. The ovary is identified; the signal intensity from the ovary depends on the acquisition parameter used. Uterine leiomyoma, endometriosis, and dermoid cyst were depicted, but further experience is needed to ascertain the specificity of the findings.

Hricak, H.; Alpers, C.; Crooks, L.E.; Sheldon, P.E.

1983-12-01

360

Radio-frequency energy quantification in magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

Mapping of radio frequency (RF) energy deposition has been challenging for 50+ years, especially, when scanning patients in the magnetic resonance imaging (MRI) environment. As result, electromagnetic simulation software is often used for estimating the specific absorption rate (SAR), the rate of RF energy deposition in tissue. The thesis work presents challenges associated with aligning information provided by electromagnetic simulation and MRI experiments. As result of the limitations of simulations, experimental methods for the quantification of SAR were established. A system for quantification of the total RF energy deposition was developed for parallel transmit MRI (a system that uses multiple antennas to excite and image the body). The system is capable of monitoring and predicting channel-by-channel RF energy deposition, whole body SAR and capable of tracking potential hardware failures that occur in the transmit chain and may cause the deposition of excessive energy into patients. Similarly, we demonstrated that local RF power deposition can be mapped and predicted for parallel transmit systems based on a series of MRI temperature mapping acquisitions. Resulting from the work, we developed tools for optimal reconstruction temperature maps from MRI acquisitions. The tools developed for temperature mapping paved the way for utilizing MRI as a diagnostic tool for evaluation of RF/microwave emitting device safety. Quantification of the RF energy was demonstrated for both MRI compatible and non-MRI-compatible devices (such as cell phones), while having the advantage of being noninvasive, of providing millimeter resolution and high accuracy.

Alon, Leeor

361

Magnetic resonance imaging in rectal cancer: a surgeon's perspective.  

PubMed

Magnetic resonance imaging (MRI) in rectal cancer was first investigated in 1999 and has become almost mandatory in planning rectal cancer treatment. MRI has a high accuracy in predicting circumferential resection margin involvement and is used to plan neoadjuvant therapy. The accuracy of MRI in assessing mesorectal lymph nodes remains moderate, as there are no reliable criteria to assess nodal involvement. MRI seems to be good in assessing peritoneal involvement in upper rectal cancer; this however has been assessed in only a few studies and needs further research. For low rectal cancers, mesorectum is thin at the level of levator ani especially in relation to prostate; so predicting circumferential resection margin involvement is not easy. However high spatial resolution coronal imaging shows levator muscles, sphincter complex and intersphincteric plane accurately. This is used to stage low rectal tumors and plan plane of surgery (standard surgery, intersphincteric resection, Extralevator abdominoperineal resection). While most centres perform MRI post chemoradiotherapy, its role in accurate staging post neoadjuvant therapy remains debatable. THe role of Diffusion weighted MRI post neoadjuvant therapy is being evaluated in research settings. PMID:24616572

Saklani, Avanish P; Bae, Sung Uk; Clayton, Amy; Kim, Nam Kyu

2014-02-28

362

Stable cerasomes for simultaneous drug delivery and magnetic resonance imaging  

PubMed Central

Magnetic liposomes have been frequently used as nanocarriers for targeted drug delivery and magnetic resonance imaging in recent years. Despite great potentials, their morphological/structural instability in the physiological environment still remains an intractable challenge for clinical applications. In this study, stable hybrid liposomal cerasomes (ie, liposomes partially coated with silica) which can co-encapsulate Fe3O4 nanoparticles and the anticancer drug paclitaxel were developed using thin film hydration method. Compared with the drug loaded liposomes, the paclitaxel-loaded magnetic cerasomes (PLMCs) exhibited much higher storage stability and better sustained release behavior. Cellular uptake study showed that the utilization of an external magnetic field significantly facilitated the internalization of PLMCs into cancer cells, resulting in potentiated drug efficacy of killing tumor cells. The T2 relaxivity (r2) of our PLMCs was much higher than that of free Fe3O4 nanoparticles, suggesting increased sensitivity in T2-weighted imaging. Given its excellent biocompatibility also shown in the study, such dual functional PLMC is potentially a promising nanosystem for effective cancer diagnosis and therapy. PMID:25395848

Cao, Zhong; Zhu, Wenjian; Wang, Wei; Zhang, Chunyang; Xu, Ming; Liu, Jie; Feng, Shi-Ting; Jiang, Qing; Xie, Xiaoyan

2014-01-01

363

A localized surface plasmon resonance imaging instrument for multiplexed biosensing.  

PubMed

Localized surface plasmon resonance (LSPR) spectroscopy has been widely used for label-free, highly sensitive measurements of interactions at a surface. LSPR imaging (LSPRi) has the full advantages of LSPR but enables high-throughput, multiplexed measurements by simultaneously probing multiple individually addressable sensors on a single sample surface. Each spatially distinct sensor can be tailored to provide data regarding different surface functionalities or reaction environments. Previously, LSPRi has focused on single-particle sensing where the size scale is very small. Here, we create defined macroscale arrays of nanoparticles that are compatible with common patterning methods such as dip-pen nanolithography and multichannel microfluidic delivery devices. With this new LSPR sensing format, we report the first demonstration of multiplexed LSPR imaging and show that the increased throughput of our instrument enables the collection of a complete Langmuir binding curve on a single sensor surface. In addition, the multiplexed LSPR sensor is highly selective, as demonstrated by the hybridization of single-stranded DNA to complementary sequences immobilized on the sensor surface. The LSPR arrays described in this work exhibit uniform sensitivity and tailorable optical properties, making them an ideal platform for high-throughput, label-free analysis of a variety of molecular binding interactions. PMID:23560643

Ruemmele, Julia A; Hall, W Paige; Ruvuna, Laura K; Van Duyne, Richard P

2013-05-01

364

Towards the invisible cryogenic system for Magnetic Resonance Imaging  

NASA Astrophysics Data System (ADS)

With about 10,000 Magnetic Resonance Imaging (MRI) systems installed worldwide, helium cooled magnets have become familiar equipment in hospitals and imaging centers. Patients and operators are only aware of the hissing sound of the Gifford-MacMahon refrigerator. Service technicians, however, still work with cryogenic fluids and cold gases, e.g. for replenishing the helium reservoir, inserting retractable current leads for magnet ramps, or replacing burst disks after a magnet quench. We will describe the steps taken at Oxford Magnet Technology towards the ultimate goal of a superconducting magnet being as simple as a household fridge. Early steps included the development of resealing quench valves, as well as permanently installed transfer siphons that only open when fully cooled to 4K. On recently launched 1.5 Tesla solenoid magnets, 500 A current leads are permanently fixed into the service turret, with hardly any boil-off penalty (40-50 cc/hr total). Ramping of the magnet has been fully automated, including electronic supervision of the gas-cooled current leads. One step ahead, the 1 Tesla High Field Open magnet is refrigerated by a single 4K Gifford MacMahon coldhead, relieving the user from the necessity to refill with helium. Our conduction cooled 0.2 Tesla HTS magnet testbed does not require liquid cryogens at any time in its life, including initial cool-down.

Steinmeyer, F.; Retz, P. W.; White, K.; Lang, A.; Stautner, W.; Smith, P. N.; Gilgrass, G.

2002-05-01

365

Paramagnetic oil emulsions as oral magnetic resonance imaging contrast agents.  

PubMed

The combination of a paramagnetic agent with an oil emulsion can uniformly enhance the small bowel. We discovered that the entire small bowel becomes homogeneously brighter than its surroundings when imaged with all commonly utilized pulse sequences. We have tried various combinations of ferric ammonium citrate, ferrous sulfate, gadolinium-DPTA and corn oil, olive oil and peanut oil. All paramagnetic oil emulsions tested were uniformly distributed throughout the small bowel, but the enhancement effect is much stronger with the ferric ammonium citrate and gadolinium-DPTA oil emulsions. We have also developed a mixture of Geritol, corn oil, ice cream and milk, which uniformly coats the small bowel wall, has good enhancement effect, tastes good, and is nutritious. With this dietary contrast, retroperitoneal structures including the pancreas can be well delineated. We conclude that the combination of a paramagnetic agent with an oil emulsion can work as a safe and effective magnetic resonance imaging (MRI) oral contrast agent with high patient acceptance. PMID:2082129

Li, K C; Ang, P G; Tart, R P; Storm, B L; Rolfes, R; Ho-Tai, P C

1990-01-01

366

Longitudinal Intensity Normalization of Magnetic Resonance Images using Patches  

PubMed Central

This paper presents a patch based method to normalize temporal intensities from longitudinal brain magnetic resonance (MR) images. Longitudinal intensity normalization is relevant for subsequent processing, such as segmentation, so that rates of change of tissue volumes, cortical thickness, or shapes of brain structures becomes stable and smooth over time. Instead of using intensities at each voxel, we use patches as image features as a patch encodes neighborhood information of the center voxel. Once all the time-points of a longitudinal dataset are registered, the longitudinal intensity change at each patch is assumed to follow an auto-regressive (AR(1)) process. An estimate of the normalized intensities of a patch at every time-point are generated from a hidden Markov model, where the hidden states are the unobserved normalized patches and the outputs are the observed patches. A validation study on a phantom dataset shows good segmentation overlap with the truth, and an experiment with real data shows more stable rates of change for tissue volumes with the temporal normalization than without. PMID:24382991

Roy, Snehashis; Carass, Aaron; Prince, Jerry L.

2013-01-01

367

Accurate Measurement of Magnetic Resonance Imaging Gradient Characteristics  

PubMed Central

Recently, gradient performance and fidelity has become of increasing interest, as the fidelity of the magnetic resonance (MR) image is somewhat dependent on the fidelity of the gradient system. In particular, for high fidelity non-Cartesian imaging, due to non-fidelity of the gradient system, it becomes necessary to know the actual k-space trajectory as opposed to the requested trajectory. In this work we show that, by considering the gradient system as a linear time-invariant system, the gradient impulse response function (GIRF) can be reliably measured to a relatively high degree of accuracy with a simple setup, using a small phantom and a series of simple experiments. It is shown experimentally that the resulting GIRF is able to predict actual gradient performance with a high degree of accuracy. The method captures not only the frequency response but also gradient timing errors and artifacts due to mechanical vibrations of the gradient system. Some discussion is provided comparing the method presented here with other analogous methods, along with limitations of these methods. PMID:25343017

Liu, Hui; Matson, Gerald B.

2014-01-01

368

A Localized Surface Plasmon Resonance Imaging Instrument for Multiplexed Biosensing  

PubMed Central

Localized surface plasmon resonance (LSPR) spectroscopy has been widely used for label-free, highly-sensitive measurements of interactions at a surface. LSPR imaging (LSPRi) has the full advantages of LSPR, but enables high-throughput, multiplexed measurements by simultaneously probing multiple individually addressable sensors on a single sample surface. Each spatially distinct sensor can be tailored to provide data regarding different surface functionalities or reaction environments. Previously, LSPRi has focused on single particle sensing where the size scale is very small. Here, we create defined macroscale arrays of nanoparticles that are compatible with common patterning methods such as dip-pen nanolithography and multi-channel microfluidic delivery devices. With this new LSPR sensing format, we report the first demonstration of multiplexed LSPR imaging and show that the increased throughput of our instrument enables the collection of a complete Langmuir binding curve on a single sensor surface. In addition, the multiplexed LSPR sensor is highly selective, as demonstrated by the hybridization of single-stranded DNA to complementary sequences immobilized on the sensor surface. The LSPR arrays described in this work exhibit uniform sensitivity and tailorable optical properties, making them an ideal platform for high-throughput, label-free analysis of a variety of molecular binding interactions. PMID:23560643

Ruemmele, Julia A.; Hall, W. Paige; Ruvuna, Laura K.; Van Duyne, Richard P.

2013-01-01

369

Gadolinium-enhanced magnetic resonance imaging of spinal tumours.  

PubMed

The use of gadolinium diethylenetriamine-penta-acetic acid (Gd-DTPA) (Magnevist) enhanced magnetic resonance imaging (0.15 T) in the assessment of spinal tumours is described. Thirty-five patients were entered into the study and a total of 39 examinations were performed. The information obtained from unenhanced T1- and T2-weighted spin-echo sequences was compared with the Gd-DTPA-enhanced T1 images. Thirty patients had intradural lesions and five had extradural lesions. A variable pattern of enhancement of intramedullary tumours was found, which in part reflected differences in the cystic component of the lesions. Extramedullary intra- and extradural lesions generally showed marked enhancement. The greatest contribution to management decisions was in the evaluation of intramedullary tumours where the use of contrast enhancement facilitated the precise localization of active tumour, differentiation of cystic and solid components of tumour, separation of tumour from peritumoral oedema and, in cases of suspected recurrence, aided distinction between tumour and both post-operative scarring and radiation damage. PMID:2605454

Rothwell, C I; Jaspan, T; Worthington, B S; Holland, I M

1989-12-01

370

Magnetic Resonance Imaging of Axial Segregation of Rotating Granular Media  

NASA Astrophysics Data System (ADS)

Certain homogeneous binary mixtures of different sized beads segregate into alternating bands of relatively pure single concentrations when rotated in a long horizontal cylinder, as in a drum mixer, about the axis of the cylinder. With continued rotation the initial banding pattern evolves with the number of bands along the axis decreasing. Some mixtures also exhibit a reversible effect and remix when the rotation speed is reduced.footnote K.M. Hill and J. Kakalios, Phys. Rev. E 52, 4393 (1995) In all these cases, radial segregation is observed prior to the axial segregation effect, where the smaller bead component is more concentrated near the center of rotation. We have used magnetic resonance imaging techniques, which can non-invasively image beneath the flowing surface, to explore the relationship between the development of the radial mode and the different segregating behaviors observed along the axis. The implications of these results for proposed mechanisms for the segregation effect will be discussed. Supported in part by NSF DMR-9057722, NSF CTS-9501437, the University of Minnesota and The Lovelace Institute.

Caprihan, A.; Hill, K. M.; Kakalios, J.

1996-03-01

371

Molecular magnetic resonance imaging of brain–immune interactions  

PubMed Central

Although the blood–brain barrier (BBB) was thought to protect the brain from the effects of the immune system, immune cells can nevertheless migrate from the blood to the brain, either as a cause or as a consequence of central nervous system (CNS) diseases, thus contributing to their evolution and outcome. Accordingly, as the interface between the CNS and the peripheral immune system, the BBB is critical during neuroinflammatory processes. In particular, endothelial cells are involved in the brain response to systemic or local inflammatory stimuli by regulating the cellular movement between the circulation and the brain parenchyma. While neuropathological conditions differ in etiology and in the way in which the inflammatory response is mounted and resolved, cellular mechanisms of neuroinflammation are probably similar. Accordingly, neuroinflammation is a hallmark and a decisive player of many CNS diseases. Thus, molecular magnetic resonance imaging (MRI) of inflammatory processes is a central theme of research in several neurological disorders focusing on a set of molecules expressed by endothelial cells, such as adhesion molecules (VCAM-1, ICAM-1, P-selectin, E-selectin, …), which emerge as therapeutic targets and biomarkers for neurological diseases. In this review, we will present the most recent advances in the field of preclinical molecular MRI. Moreover, we will discuss the possible translation of molecular MRI to the clinical setting with a particular emphasis on myeloperoxidase imaging, autologous cell tracking, and targeted iron oxide particles (USPIO, MPIO). PMID:25505871

Gauberti, Maxime; Montagne, Axel; Quenault, Aurélien; Vivien, Denis

2014-01-01

372

Indications requiring preoperative magnetic resonance imaging before knee arthroscopy  

PubMed Central

Introduction Knee arthroscopy knee is gold standard in diagnosis and simultaneous treatment of knee disorders. But most patients undergo magnetic resonance imaging (MRI) before arthroscopy, although MRI results are not always consistent with arthroscopic findings. This raises the question in which suspected diagnoses MRI really has influence on diagnosis and consecutive surgical therapy. Material and methods Preoperative MRI of 330 patients with knee disorders were compared with arthroscopic findings. The MRI were performed by 23 radiologists without specialization in musculoskeletal diagnostics. Specificity, sensitivity, negative/positive predictive value and accuracy of MRI were calculated in comparison to arthroscopic findings. Results We found sensitivity/specificity of 58%/93% for anterior horn, 94%/46% for posterior horn of medial meniscus and 71%/81% for anterior and 62%/82% for posterior horn of lateral meniscus. Related to anterior cruciate ligament injuries we showed sensitivity/specificity of 82%/91% for grade 0 + I and 72%/96% for grade II + III. For Cartilage damage sensitivity/specificity of 98%/7% for grade I-, 89%/29% for grade II-, 96%/38% for grade III- and 96%/69% for grade IV-lesions were revealed. Conclusions The MRI should not be used as routine diagnostic tool for knee pain. No relevant information for meniscal lesions and anterior cruciate ligament ruptures has been gained with MRI from non-specialized outside imaging centres. The MRI should not be used as routine diagnostic tool for knee pain. No relevant information for meniscal lesions and anterior cruciate ligament ruptures has been gained with MRI from non-specialized outside imaging centres.

Roßbach, Björn Peter; Pietschmann, Matthias Frank; Gülecyüz, Mehmet Fatih; Niethammer, Thomas Richard; Ficklscherer, Andreas; Wild, Stefan; Jansson, Volkmar

2014-01-01

373

Automated Analysis of Craniofacial Morphology Using Magnetic Resonance Images  

PubMed Central

Quantitative analysis of craniofacial morphology is of interest to scholars working in a wide variety of disciplines, such as anthropology, developmental biology, and medicine. T1-weighted (anatomical) magnetic resonance images (MRI) provide excellent contrast between soft tissues. Given its three-dimensional nature, MRI represents an ideal imaging modality for the analysis of craniofacial structure in living individuals. Here we describe how T1-weighted MR images, acquired to examine brain anatomy, can also be used to analyze facial features. Using a sample of typically developing adolescents from the Saguenay Youth Study (N?=?597; 292 male, 305 female, ages: 12 to 18 years), we quantified inter-individual variations in craniofacial structure in two ways. First, we adapted existing nonlinear registration-based morphological techniques to generate iteratively a group-wise population average of craniofacial features. The nonlinear transformations were used to map the craniofacial structure of each individual to the population average. Using voxel-wise measures of expansion and contraction, we then examined the effects of sex and age on inter-individual variations in facial features. Second, we employed a landmark-based approach to quantify variations in face surfaces. This approach involves: (a) placing 56 landmarks (forehead, nose, lips, jaw-line, cheekbones, and eyes) on a surface representation of the MRI-based group average; (b) warping the landmarks to the individual faces using the inverse nonlinear transformation estimated for each person; and (3) using a principal components analysis (PCA) of the warped landmarks to identify facial features (i.e. clusters of landmarks) that vary in our sample in a correlated fashion. As with the voxel-wise analysis of the deformation fields, we examined the effects of sex and age on the PCA-derived spatial relationships between facial features. Both methods demonstrated significant sexual dimorphism in craniofacial structure in areas such as the chin, mandible, lips, and nose. PMID:21655288

Chakravarty, M. Mallar; Aleong, Rosanne; Leonard, Gabriel; Perron, Michel; Pike, G. Bruce; Richer, Louis; Veillette, Suzanne; Pausova, Zdenka; Paus, Tomáš

2011-01-01

374

Quantitative kinetics and angle scanning surface plasmon resonance imaging  

NASA Astrophysics Data System (ADS)

Surface plasmon resonance (SPR) has been used extensively to monitor the kinetics of the adsorption of molecules at surfaces. We have quantitatively evaluated the accuracy of three different methods for measuring the kinetics of the adsorption of molecules using SPR by modeling the SPR response for an isotropic optical multilayer system. The SPR kinetic methods included the tracking of the minimum of the SPR reflected intensity and the tracking of the SPR reflected intensity at a fixed angle of incidence theta i, as well as a third novel method, the tracking of the inflection point of the SPR reflected intensity. SPR minimum tracking and SPR inflection point tracking were found to yield quantitatively accurate measures of the time constant tau of the kinetics, whereas the accuracy of the tau values determined using SPR fixed angle reflectivity tracking was found to vary significantly with the choice of fixed thetai. A method was developed to deconvolute the SPR curve shape from the SPR fixed angle reflectivity data resulting in a dramatic increase in the accuracy of the tau values. The SPR kinetic method modeling results were validated by designing and constructing an automated angle scanning SPR imaging instrument. The instrument incorporated a novel method to remove two imaging artifacts, beam walking and image compression, that severely impact the ability to track regions of interest (ROIs) within the image as thetai is varied. By using this novel method, we are able to define multiple ROIs for an arbitrary thetai and correctly track these ROIs at all other values of thetai. In agreement with our modeling results, we show experimentally that the accuracy of the tau values obtained from the SPR fixed angle reflectivity tracking method depends significantly on the choice of fixed theta i, and that the accuracy of the tau values improves dramatically by deconvoluting the SPR curve shape from the SPR fixed angle reflectivity data. We have also used our SPR imaging instrument to study the enzymatic degradation of cellulose fibers that have been heterogeneously distributed on a gold film coated with a thin layer of thioglucose.

Allen, Scott G.

375

How to diagnose MSA early: the role of magnetic resonance imaging  

Microsoft Academic Search

Summary.  The clinical differentiation between Parkinson’s disease (PD) and multiple system atrophy (MSA) remains a challenge for each\\u000a neurologist. The use of different magnetic resonance imaging (MRI) techniques including conventional MRI, proton magnetic\\u000a resonance spectroscopy (MRS), diffusion-weighted imaging (DWI), magnetization transfer imaging (MTI) and MR volumetry (MRV)\\u000a offer the potential for objective criteria in the differential diagnosis of neurodegenerative parkinsonism. The

K. Seppi; M. F. H. Schocke; G. K. Wenning; W. Poewe

2005-01-01

376

Echo-Planar Magnetic Resonance Imaging Studies of Frontal Cortex Activation During Word Generation in Humans  

Microsoft Academic Search

Nine subjects were studied by high-speed magnetic resonance imaging while performing language-based tasks. Subjects were asked either to repeat or to generate verbs associated with nouns read by an experimenter while magnetic resonance images were obtained of the left inferior frontal lobe. The echo-planar imaging sequence was used with a gradient echo time of 70 ms to give an apparent

Gregory McCarthy; Andrew M. Blamire; Douglas L. Rothman; Rolf Gruetter; Robert G. Shulman

1993-01-01

377

High frequency resonant waveguide grating imager for assessing drug-induced cardiotoxicity  

NASA Astrophysics Data System (ADS)

We report a high-frequency resonant waveguide grating imager for assessing compound-induced cardiotoxicity. The imager sweeps the wavelength range from 823 nm to 838 nm every 3 s to identify and monitor compound-induced shifts in resonance wavelength and then switch to the intensity-imaging mode to detect the beating rhythm and proarrhythmic effects of compounds on induced pluripotent stem cell-derived cardiomyocytes. This opens possibility to study cardiovascular biology and compound-induced cardiotoxicity.

Ferrie, Ann M.; Wu, Qi; Deichmann, Oberon D.; Fang, Ye

2014-05-01

378

Breast cancer screening and problem solving using mammography, ultrasound, and magnetic resonance imaging.  

PubMed

Although mammography is the mainstay of early breast cancer detection, it has known limitations, particularly in women with dense breasts. As a result, additional imaging modalities, including ultrasound and contrast-enhanced magnetic resonance imaging, are also being used to supplement mammography in the early detection of occult breast cancer. This article reviews the indications and efficacy of mammography, ultrasound, and magnetic resonance imaging as both screening and diagnostic tools. PMID:21343800

Hooley, Regina J; Andrejeva, Liva; Scoutt, Leslie M

2011-03-01

379

Proton Density-Weighted Functional Magnetic Resonance Imaging at 0.35 Tesla  

Microsoft Academic Search

Functional magnetic resonance imaging of healthy human volunteers was carried out at 0.35T MRI system, using proton-density weighted turbo spin-echo imaging. It aims at verifying the proton-density change contribution to spin-echo functional magnetic resonance imaging. And try to get better effect of fMRI studies at 0.35T MRI system. Results demonstrated that signal intensity changes in motor area of the brain

Ping. Yang; Jinxing. Wang; Yuesheng Chao; Guang Lu; Jinquan Shi

2008-01-01

380

Extragastrointestinal stromal tumors: Computed tomography and magnetic resonance imaging findings.  

PubMed

Extragastrointestinal stromal tumors (EGISTs) are rare mesenchymal tumors that originate outside the gastrointestinal tract. The aim of the present study was to investigate the computed tomography (CT) and magnetic resonance imaging (MRI) features of EGISTs and analyze the correlations between radiological findings and pathological features. CT and MRI images of 24 patients with EGISTs were reviewed retrospectively. Patient demographics and tumor characteristics, including localization, size, contours, borders, cystic-necrotic components, calcification, hemorrhage, tumor vessels, attenuation and intensity, degree and pattern of enhancement, ascites, tumor invasion, lymphadenopathy and distant metastasis were recorded. Statistical analyses to compare the radiological characteristics of low- and high-grade EGISTs were performed with ?(2) or Fisher's exact tests. The mean patient age at the time of presentation was 53 years. A total of 24 EGISTs were detected, originating in the omentum (n=4), mesentery (n=19) and retroperitoneum (n=1), respectively. The EGISTs displayed a predominantly spindle cell subtype (87.5%; 21/24). The majority of the EGISTs appeared as large (>10 cm; 70.8%; 17/24), round or oval (66.7%; 16/24), cystic-solid (87.5%; 21/24) and ill-defined (66.7%; 16/24) soft-tissue masses. The EGISTs were hypodense (69.6%; 16/23) or isodense (30.4%; 7/23) on CT images, hypointense (50%; 3/6), isointense (33.3%; 2/6) or hyperintense (16.7%; 1/6) on T1-weighted imaging (T1WI), and hyperintense on T2WI (100%; 6/6) and diffusion-WI (DWI; 100%; 6/6). A total of 54.2% (13/24) of the EGISTs displayed tumor vessels. Overall, 95.8% (23/24) of the masses showed marked enhancement and 87.5% (21/24) demonstrated heterogeneous enhancement. Calcification, hemorrhage, ascites and lymphadenopathy were rare characteristics in the EGISTs. Distant metastases were present in 10 patients (41.7%). The size, borders, tumor vessels and distant metastasis correlated with high-grade EGISTs [>5 mitoses/50 high-power fields (HPFs)] (P<0.05). The results of the present study indicated that clinical and radiological features, including advanced age, a large tumor size, cystic-necrotic components, rare lymphadenopathy, a heterogeneous enhancement pattern and hepatic metastasis may aid in the diagnosis of EGISTs. Radiological characteristics, such as a large size (>10 cm), ill-defined borders, tumor vessels and distant metastasis, can provide useful information in identifying the malignant behavior of EGISTs. PMID:25435959

Zhu, Jingqi; Yang, Zhangwei; Tang, Guangyu; Wang, Zhongqiu

2015-01-01

381

Multiprocessing DSP imaging system and instrumentation design for magnetic resonance spectroscopy/imaging  

NASA Astrophysics Data System (ADS)

The architectural design of an image processing system and its instrumentation is elucidated here in this presentation, based upon the multiprocessing TMS320C82 DSP processors, working under a specially-defined MAEVRISC-DSP (Multidimensional Application-Embedded Vector RISC-DSP) architecture, that blends high-precision and high- performance (120 MFLOPS digital and 100 MSPS analog) data acquisition with efficient signal processing architecture design and prevalent Tagged MRI pulse sequence algorithms, specifically optimized for the medical imaging applications of Magnetic Resonance Spectroscopy and Imaging (MRI) tomography, while at the same time giving a low-cost alternative to extremely-expensive MRI systems. Alongside the system definition, the design of a new magneto-optical instrumentation is also presented, named SQUID and LPDA- based Field Equalization and Susceptibility Detection sensing, which works upon the recently-defined Tunneling Photon Resonance effect, mainly devised with non-ionizing human brain tumor diagnosis and localization in perspective, whose brief account is highlighted here.

Bukhari, S. M. H.

1998-09-01

382

Multiplane magnetic resonance imaging of the heart and major vessels: studies in normal volunteers  

SciTech Connect

The feasibility of magnetic resonance imaging for defining anatomy of internal cardiac structures and major blood vessels was assessed in 14 normal subjects. Both electrocardiogram-gated and standard spin-echo images were obtained. Gated images provided better visualization of internal cardiac morphology and of upper mediastinal vessels than did nongated images. Trabecular detail and components of the mitral valve could be resolved. All segments of the left ventricular wall could be evaluated by combining axial, coronal, and sagittal images. Gated acquisition of magnetic resonance images did not increase imaging time; five transverse slices of the left ventricle were obtained in 6.0-8.5 min. The good image quality, ease of gated acquisition, large field of view, capability of direct imaging in multiple planes, and noninvasiveness of the technique suggest that it will be an important imaging method in cardiovascular disease.

Higgins, C.B.; Stark, D.; McNamara, M.; Lanzer, P.; Crooks, L.E.; Kaufman, L.

1984-04-01

383

Combined magnetic resonance, fluorescence, and histology imaging strategy in a human breast tumor xenograft model  

PubMed Central

Applications of molecular imaging in cancer and other diseases frequently require combining in vivo imaging modalities, such as magnetic resonance and optical imaging, with ex vivo optical, fluorescence, histology, and immunohistochemical (IHC) imaging, to investigate and relate molecular and biological processes to imaging parameters within the same region of interest. We have developed a multimodal image reconstruction and fusion framework that accurately combines in vivo magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI), ex vivo brightfield and fluorescence microscopic imaging, and ex vivo histology imaging. Ex vivo brightfield microscopic imaging was used as an intermediate modality to facilitate the ultimate link between ex vivo histology and in vivo MRI/MRSI. Tissue sectioning necessary for optical and histology imaging required generation of a three-dimensional (3D) reconstruction module for 2D ex vivo optical and histology imaging data. We developed an external fiducial marker based 3D reconstruction method, which was able to fuse optical brightfield and fluorescence with histology imaging data. Registration of 3D tumor shape was pursued to combine in vivo MRI/MRSI and ex vivo optical brightfield and fluorescence imaging data. This registration strategy was applied to in vivo MRI/MRSI, ex vivo optical brightfield/fluorescence, as well as histology imaging data sets obtained from human breast tumor models. 3D human breast tumor data sets were successfully reconstructed and fused with this platform. PMID:22945331

Jiang, Lu; Greenwood, Tiffany R.; Amstalden van Hove, Erika R.; Chughtai, Kamila; Raman, Venu; Winnard, Paul T.; Heeren, Ron; Artemov, Dmitri; Glunde, Kristine

2014-01-01

384

Phase Imaging of Magnetic Nanostructures Using Resonant Soft X-Ray Holography  

SciTech Connect

We demonstrate phase imaging by means of resonant soft x-ray holography. Our holographic phase-contrast method utilizes the strong energy-dependence of the refractive index at a characteristic x-ray absorption resonance. The general concept is shown by using a Co/Pd multilayer sample which exhibits random nanosized magnetic domains. By tuning below the Co L-edge resonance, our quantitative and spectroscopic phase method allows high-contrast imaging of nanoscale electronic and magnetic order while increasing the probing depth and decreasing the radiation dose by an order of magnitude. The complex refractive index is quantitatively obtained through the interference between resonant and nonresonant scattering.

Scherz, A.; Schlotter, W.F.; Chen, K.; Rick, R.; Stohr, J.; Luning, J.; McNulty, I.; Gunther, C.; Radu, F.; Eberhardt, W.; Hellwig, O.; Eisebitt, S.; /SLAC, SSRL /Stanford U., Appl. Phys. Dept. /BESSY, Berlin /Argonne /Hitachi Global Stor. Tech., San Jose

2009-04-30

385

SQUID-Detected Magnetic Resonance Imaging in MicroteslaFields  

SciTech Connect

Magnetic resonance imaging (MRI) has developed into a powerful clinical tool for imaging the human body (1). This technique is based on nuclear magnetic resonance (NMR) of protons (2, 3) in a static magnetic field B{sub 0}. An applied radiofrequency pulse causes the protons to precess about B{sub 0} at their Larmor frequency {nu}{sub 0} = ({gamma}/2{pi})B{sub 0}, where {gamma} is the gyromagnetic ratio; {gamma}/2{pi} = 42.58 MHz/tesla. The precessing protons generate an oscillating magnetic field and hence a voltage in a nearby coil that is amplified and recorded. The application of three-dimensional magnetic field gradients specifies a unique magnetic field and thus an NMR frequency in each voxel of the subject, so that with appropriate encoding of the signals one can acquire a complete image (4). Most clinical MRI systems involve magnetic fields generated by superconducting magnets, and the current trend is to higher magnetic fields than the widely used 1.5-T systems (5). Nonetheless, there is ongoing interest in the development of less expensive imagers operating at lower fields. Commercially available 0.2-T systems based on permanent magnets offer both lower cost and a more open access than their higher-field counterparts, at the expense of signal-to-noise-ratio (SNR) and spatial resolution. At the still lower field of 0.03 mT maintained by a conventional, room-temperature solenoid, Connolly and co-workers (6, 7) obtain good spatial resolution and signal-to-noise ratio (SNR) by prepolarizing the protons in a field B{sub p} of 0.3 T. Prepolarization (8) enhances the magnetic moment of an ensemble of protons over that produced by the lower precession field; after the polarizing field is removed, the higher magnetic moment produces a correspondingly larger signal during its precession in B{sub 0}. Using the same method, Stepisnik et al. (9) obtained MR images in the Earth's magnetic field ({approx} 50 {micro}T). Alternatively, one can enhance the signal amplitude in MRI using laser polarized noble gases such as {sup 3}He or {sup 129}Xe (10-12). Hyperpolarized gases were used successfully to image the human lung in fields on the order of several mT (13-15). To overcome the sensitivity loss of Faraday detection at low frequencies, ultrasensitive magnetometers based on the Superconducting QUantum Interference Device (SQUID) (16) are used to detect NMR and MRI signals (17-24). Recently, SQUID-based MRI systems capable of acquiring in vivo images have appeared. For example, in the 10-mT system of Seton et al. (18) signals are coupled to a SQUID via a superconducting tuned circuit, while Clarke and coworkers (22, 25, 26) developed a system at 132 {micro}T with an untuned input circuit coupled to a SQUID. In a quite different approach, atomic magnetometers have been used recently to detect the magnetization (27) and NMR signal (28) of hyperpolarized gases. This technique could potentially be used for low-field MRI in the future. The goal of this review is to summarize the current state-of-the-art of MRI in microtesla fields detected with SQUIDs. The principles of SQUIDs and NMR are briefly reviewed. We show that very narrow NMR linewidths can be achieved in low magnetic fields that are quite inhomogeneous, with illustrative examples from spectroscopy. After describing our ultralow-field MRI system, we present a variety of images. We demonstrate that in microtesla fields the longitudinal relaxation T{sub 1} is much more material dependent than is the case in high fields; this results in a substantial improvement in 'T{sub 1}-weighted contrast imaging'. After outlining the first attempts to combine microtesla NMR with magnetoencephalography (MEG) (29), we conclude with a discussion of future directions.

Moessle, Michael; Hatridge, Michael; Clarke, John

2006-08-14

386

Use magnetic resonance imaging to assess articular cartilage  

PubMed Central

Magnetic resonance imaging (MRI) enables a noninvasive, three-dimensional assessment of the entire joint, simultaneously allowing the direct visualization of articular cartilage. Thus, MRI has become the imaging modality of choice in both clinical and research settings of musculoskeletal diseases, particular for osteoarthritis (OA). Although radiography, the current gold standard for the assessment of OA, has had recent significant technical advances, radiographic methods have significant limitations when used to measure disease progression. MRI allows accurate and reliable assessment of articular cartilage which is sensitive to change, providing the opportunity to better examine and understand preclinical and very subtle early abnormalities in articular cartilage, prior to the onset of radiographic disease. MRI enables quantitative (cartilage volume and thickness) and semiquantitative assessment of articular cartilage morphology, and quantitative assessment of cartilage matrix composition. Cartilage volume and defects have demonstrated adequate validity, accuracy, reliability and sensitivity to change. They are correlated to radiographic changes and clinical outcomes such as pain and joint replacement. Measures of cartilage matrix composition show promise as they seem to relate to cartilage morphology and symptoms. MRI-derived cartilage measurements provide a useful tool for exploring the effect of modifiable factors on articular cartilage prior to clinical disease and identifying the potential preventive strategies. MRI represents a useful approach to monitoring the natural history of OA and evaluating the effect of therapeutic agents. MRI assessment of articular cartilage has tremendous potential for large-scale epidemiological studies of OA progression, and for clinical trials of treatment response to disease-modifying OA drugs. PMID:22870497

Wang, Yuanyuan; Wluka, Anita E.; Jones, Graeme; Ding, Changhai

2012-01-01

387

The Osteoarthritis Initiative (OAI) magnetic resonance imaging quality assurance update  

PubMed Central

Objective Longitudinal quantitative evaluation of cartilage disease requires reproducible measurements over time. We report 8 years of quality assurance (QA) metrics for quantitative magnetic resonance (MR) knee analyses from the Osteoarthritis Initiative (OAI) and show the impact of MR system, phantom, and acquisition protocol changes. Method Key 3 T MR QA metrics, including signal-to-noise, signal uniformity, T2 relaxation times, and geometric distortion, were quantified monthly on two different phantoms using an automated program. Results Over 8 years, phantom measurements showed root-mean-square coefficient-of-variation reproducibility of <0.25% (190.0 mm diameter) and <0.20% (148.0 mm length), resulting in spherical volume reproducibility of <0.35%. T2 relaxation time reproducibility varied from 1.5% to 5.3%; seasonal fluctuations were observed at two sites. All other QA goals were met except: slice thicknesses were consistently larger than nominal on turbo spin echo images; knee coil signal uniformity and signal level varied significantly over time. Conclusions The longitudinal variations for a spherical volume should have minimal impact on the accuracy and reproducibility of cartilage volume and thickness measurements as they are an order of magnitude smaller than reported for either unpaired or paired (repositioning and reanalysis) precision errors. This stability should enable direct comparison of baseline and follow-up images. Cross-comparison of the geometric results from all four OAI sites reveal that the MR systems do not statistically differ and enable results to be pooled. MR QA results identified similar technical issues as previously published. Geometric accuracy stability should have the greatest impact on quantitative analysis of longitudinal change in cartilage volume and thickness precision. PMID:23092792

Schneider, E.; NessAiver, M.

2012-01-01

388

Sources of signal fluctuations in functional magnetic resonance imaging at 7 Tesla  

Microsoft Academic Search

High-field magnetic resonance imaging (MRI) systems allow for critical improvements in image signal-to-noise ratio (SNR), potentially leading to higher sensitivity and spatial resolution for functional MRI (fMRI). 3D segmented echo volumar imaging (EVI) has recently been proposed for high- resolution fMRI at ultra-high fields. It provides higher image SNR than standard 2D echo planar imaging (EPI), but is also thought

Joao P. F. Jorge; P. Figueiredo; W. van der Zwaag; J. P. Marques

2011-01-01

389

High-resolution imaging and spectroscopy of multipolar plasmonic resonances in aluminum nanoantennas.  

PubMed

We report on the high resolution imaging of multipolar plasmonic resonances in aluminum nanoantennas using electron energy loss spectroscopy (EELS). Plasmonic resonances ranging from near-infrared to ultraviolet (UV) are measured. The spatial distributions of the multipolar resonant modes are mapped and their energy dispersion is retrieved. The losses in the aluminum antennas are studied through the full width at half-maximum of the resonances, unveiling the weight of both interband and radiative damping mechanisms of the different multipolar resonances. In the blue-UV spectral range, high order resonant modes present a quality factor up to 8, two times higher than low order resonant modes at the same energy. This study demonstrates that near-infrared to ultraviolet tunable multipolar plasmonic resonances in aluminum nanoantennas with relatively high quality factors can be engineered. Aluminum nanoantennas are thus an appealing alternative to gold or silver ones in the visible and can be efficiently used for UV plasmonics. PMID:25207386

Martin, Jérôme; Kociak, Mathieu; Mahfoud, Zackaria; Proust, Julien; Gérard, Davy; Plain, Jérôme

2014-10-01

390

Should magnetic resonance imaging or computed tomography be the primary brain imaging modality in the transient ischemic attack clinic?  

PubMed Central

Objective The Royal College of Physicians and National Institute of Clinical Excellence have recommended that magnetic resonance imaging should be the modality of choice for cerebral imaging in transient ischemic attack patients. However, implementation of this is often difficult. Therefore, it is important to know whether magnetic resonance imaging contributes significantly to early clinical management in transient ischemic attack patients. Design A retrospective case-notes review of 65 consecutive patients seen by one neurology trainee (with consultant review), in a neurovascular service where computed tomography has been the primary cerebral imaging modality. Setting Outpatient TIA/Neurovascular clinic at Imperial College hospital. Participants 65 consecutive patients seen by one neurology trainee (with consultant review). Main outcome measure We recorded the preliminary clinical diagnosis, details of investigations performed and whether or not patients had a magnetic resonance imaging brain scan subsequently, the number followed up in clinic and the final diagnosis. Results Of the 65 cases seen, 55% were classified initially as transient ischemic attack/stroke mimics. Of the 29 cases (45%) that were classified as transient ischemic attack, all had computed tomography scans, 12 had magnetic resonance imaging scans subsequently and 14 were followed up several weeks later. Of the 36 cases classified as stroke mimics, 27 had computed tomography scans immediately and 31 had carotid Dopplers, six subsequently had magnetic resonance imaging scans and 14 were followed up in clinic. Only two patients had their diagnosis revised on the basis of the magnetic resonance imaging. Conclusions Our study suggests that magnetic resonance imaging brain changes the diagnosis in a relatively small percentage of cases. A good history and examination remain paramount in the assessment of patients presenting to the transient ischemic attack clinic, particularly when more than 50% of cases referred are transient ischemic attack/stroke mimics. PMID:25408918

Ganesalingam, Jeban

2014-01-01

391

Myelin Imaging Compound (MIC)-enhanced Magnetic Resonance Imaging of Myelination  

PubMed Central

The vertebrate nervous system is characterized by myelination, a fundamental biological process that protects the axons and facilitates electric pulse transduction. Damage to myelin is considered a major effect of autoimmune diseases such as multiple sclerosis (MS). Currently, therapeutic interventions are focused on protecting myelin integrity and promoting myelin repair. These efforts need to be accompanied by an effective imaging tool that correlates the disease progression with the extent of myelination. To date, magnetic resonance imaging (MRI) is the primary imaging technique to detect brain lesions in MS. However, conventional MRI cannot differentiate demyelinated lesions from other inflammatory lesions, and therefore cannot predict disease progression in MS. To address this problem, we have prepared a Gd-based contrast agent, termed MIC (Myelin Imaging Compound), which binds to myelin with high specificity. In this work, we demonstrate that MIC exhibits a high kinetic stability towards transmetallation with promising relaxometric properties. MIC was used for in vivo imaging of myelination following intracerebroventricular infusion in the rat brain. MIC was found to distribute preferentially in highly myelinated regions and was able to detect regions of focally induced demyelination. PMID:22098543

Frullano, Luca; Zhu, Junqing; Wang, Changning; Wu, Chunying; Miller, Robert H.; Wang, Yanming

2012-01-01

392

Voxelwise multivariate analysis of multimodality magnetic resonance imaging  

PubMed Central

Most brain magnetic resonance imaging (MRI) studies concentrate on a single MRI contrast or modality, frequently structural MRI. By performing an integrated analysis of several modalities, such as structural, perfusion-weighted, and diffusion-weighted MRI, new insights may be attained to better understand the underlying processes of brain diseases. We compare two voxelwise approaches: (1) fitting multiple univariate models, one for each outcome and then adjusting for multiple comparisons among the outcomes and (2) fitting a multivariate model. In both cases, adjustment for multiple comparisons is performed over all voxels jointly to account for the search over the brain. The multivariate model is able to account for the multiple comparisons over outcomes without assuming independence because the covariance structure between modalities is estimated. Simulations show that the multivariate approach is more powerful when the outcomes are correlated and, even when the outcomes are independent, the multivariate approach is just as powerful or more powerful when at least two outcomes are dependent on predictors in the model. However, multiple univariate regressions with Bonferroni correction remains a desirable alternative in some circumstances. To illustrate the power of each approach, we analyze a case control study of Alzheimer's disease, in which data from three MRI modalities are available. PMID:23408378

Naylor, Melissa G.; Cardenas, Valerie A.; Tosun, Duygu; Schuff, Norbert; Weiner, Michael; Schwartzman, Armin

2015-01-01

393

Pathological Correlates of White Matter Hyperintensities on Magnetic Resonance Imaging.  

PubMed

Background/Aims: We investigated the histopathological correlates of white matter hyperintensities (WMHs) in participants with Alzheimer's disease (AD) or cerebrovascular disease, and in aged controls. Methods: We reviewed 57 participants who had neuropathology and in whom neuroimaging was done. In addition to AD pathology, cortical microinfarcts, lacunes, and cerebral hemorrhages were assessed. Small-vessel disease included arteriolosclerosis and cerebral amyloid angiopathy. Postmortem brain tissue corresponding to regions of WMHs was investigated in 14 participants. The variables included: demyelination of the deep and periventricular white matter (WM), atrophy of the ventricular ependyma, and thickness of blood vessels. Partial Spearman's rank test and linear regression analysis, adjusted for age at the clinical evaluation and the duration to death, were performed. Results: The severity of arteriosclerosis was correlated with the volume of periventricular hyperintensity (PVH) estimated by magnetic resonance imaging. Deep white matter hyperintensity (DWMH) volume was correlated with the presence of cortical microinfarcts and cerebral hemorrhages. The severity of the breakdown of the ventricular lining was correlated with PVHs, and DWMHs correlated with the severity of deep WM demyelination. The diameter of small blood vessels was not associated with WMHs. Conclusion: WMHs are consistent with small-vessel disease and increase the tissue water content. We found no association between WMHs and the thickness of small blood vessels. © 2014 S. Karger AG, Basel. PMID:25401390

Shim, Yong Soo; Yang, Dong-Won; Roe, Catherine M; Coats, Mary A; Benzinger, Tammie L; Xiong, Chengjie; Galvin, James E; Cairns, Nigel J; Morris, John C

2014-11-01

394

Imaging the cell membrane with surface plasmon resonance phase microscopy  

NASA Astrophysics Data System (ADS)

Molecular interactions occurring on or near cell membrane surfaces are expected to have different properties from those occurring in bulk solutions. In order to analyze molecular interactions between the cell membrane with biomolecules having no additional fluorescence labeling, a microscope based on the integration of surface plasmon resonance (SPR) and common-path phase-shift interferometry (PSI) techniques is developed and used to study the cell adhesion and migration on the biosurfaces. The surface plasmons are excited by light via the attenuated total reflection method. The common-path PSI technique has features of long-term stability, even when subjected to external disturbances. Hence, the developed SPR phase microscope meets the requirements of real-time kinetic imaging. The proposed common-path SPR-PSI microscope demonstrates a detection limit of 2x10 -7 refractive index unit and a long-term phase stability of 2.5x10 -4 ? root mean square over four hours. The developed microscope is successfully applied to the real-time observation the live cell membranes with thrombomodulin proteins.

He, R.-Y.; Su, Y.-D.; Chang, G.-L.; Chen, S.-J.

2006-08-01

395

Assessing Tumor Angiogenesis with Dynamic Contrast Enhanced Magnetic Resonance Imaging  

NASA Astrophysics Data System (ADS)

Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) is a method able of assessing microvascular changes at high spatial resolution and without ionizing radiation. The microcirculation and structure of tumors are fundamentally chaotic in that tumor-derived factors stimulate the endothelial cells to form new small vessels (angiogenesis) and this vasculature deviates markedly from normal hierarchical branching patterns. The tumor-induced microvascular changes lead to blood flow that is both spatially and temporally more heterogeneous than the efficient and uniform perfusion of normal organs and tissues. DCE-MRI allows for the assessment of perfusion and permeability of the tumor microvasculature, including the network of vessels with diameters less than 100 ?m, which are beyond the resolution of conventional angiograms. The microvessel permeability to small molecular weight contrast media as well as measures of tumor response can be assessed with different analysis techniques ranging from simple measures of enhancement to pharmacokinetic models. In this work, such DCE-MRI analysis techniques are discussed.

Esparza-Coss, Emilio; Jackson, Edward F.

2006-09-01

396

Tissue oxygen saturation mapping with magnetic resonance imaging.  

PubMed

A quantitative estimate of cerebral blood oxygen saturation is of critical importance in the investigation of cerebrovascular disease. While positron emission tomography can map in vivo the oxygen level in blood, it has limited availability and requires ionizing radiation. Magnetic resonance imaging (MRI) offers an alternative through the blood oxygen level-dependent contrast. Here, we describe an in vivo and non-invasive approach to map brain tissue oxygen saturation (StO2) with high spatial resolution. StO2 obtained with MRI correlated well with results from blood gas analyses for various oxygen and hematocrit challenges. In a stroke model, the hypoxic areas delineated in vivo by MRI spatially matched those observed ex vivo by pimonidazole staining. In a model of diffuse traumatic brain injury, MRI was able to detect even a reduction in StO2 that was too small to be detected by histology. In a F98 glioma model, MRI was able to map oxygenation heterogeneity. Thus, the MRI technique may improve our understanding of the pathophysiology of several brain diseases involving impaired oxygenation. PMID:25005878

Christen, Thomas; Bouzat, Pierre; Pannetier, Nicolas; Coquery, Nicolas; Moisan, Anaïck; Lemasson, Benjamin; Thomas, Sébastien; Grillon, Emmanuelle; Detante, Olivier; Rémy, Chantal; Payen, Jean-François; Barbier, Emmanuel Luc

2014-09-01

397

Magnetic resonance imaging of meniscal degeneration in asymptomatic knees.  

PubMed

Histopathological studies have suggested that spontaneous degeneration of knee menisci predisposes to symptomatic tears. We used magnetic resonance (MR) imaging to study noninvasively 20 patients with documented meniscal tears in one knee but asymptomatic contralateral knees, 18 normal controls, and 15 patients with symptomatic nonmeniscal knee disorders. A scoring system for MR signal changes was developed, and differences between the three groups were tested for significance by a multivariate analysis of covariance. MR signal changes in the menisci begin at around 30 years of age, progress with age, occur in both men and women, and occur in subjects who are inactive as well as those who undergo habitual knee stress exercises. Most subjects with documented meniscal tears in one knee have MR signals in the asymptomatic contralateral knee that reflect a more advanced degree of meniscal degeneration than in age-comparable normal controls or patients with nonmeniscal knee disorders. After adjustment for potential confounding variables, weight, and sex, the mean scores in the asymptomatic knee of patients with meniscal disease are significantly higher than those of normal controls (p = 0.021) and nonmeniscal disease patients (p = 0.019). These results document the occurrence of age-dependent degeneration within knee menisci, and support the hypothesis that a segment of the population has pre-existing meniscal degeneration predisposing them to traumatic or spontaneous meniscal tears. PMID:2324849

Negendank, W G; Fernandez-Madrid, F R; Heilbrun, L K; Teitge, R A

1990-05-01

398

Spatially resolved ferromagnetic resonance: Imaging of ferromagnetic eigenmodes  

SciTech Connect

Fast magnetization dynamics of ferromagnetic elements on sub-micron length scales is currently attracting substantial scientific interest. Studying the ferromagnetic eigenmodes in such systems provides valuable information in order to trace back the dynamical response to the underlying micromagnetic properties. The inherent time structure of third generation synchrotron sources allows for time-resolved imaging (time resolution: 70-100 ps) of magnetization dynamics at soft x-ray microscopes (lateral resolution down to 20 nm). Stroboscopic pump-and-probe experiments were performed on micron-sized Permalloy samples at a full-field magnetic transmission x-ray microscope (XM-1, beamline 6.1.2) at the ALS at Berkeley, CA. Complementary to these time-domain experiments a frequency-domain 'spatially resolved ferromagnetic resonance' (SR-FMR) technique was applied to magnetic x-ray microscopy. In contrast to time-domain measurements which reflect a broadband excitation of the magnetization, the frequency-domain SR-FMR technique allows for detailed studies of specific ferromagnetic eigenmodes. First SR-FMR experiments at a scanning x-ray transmission microscope (STXM, ALS, BL 11.0.2) are reported. The sample, a 1x1 {mu}m{sup 2} Permalloy pattern, was excited by an alternating magnetic field with a frequency of 250 MHz. By varying the phase relation between the sine excitation and the x-ray flashes of the synchrotron, the dynamics of a vortex motion eigenmode was investigated in time and space.

Puzic, Aleksandar; Waeyenberge, Bartel van; Chou, K.W.; Fischer, Peter; Stoll, Hermann; Schuetz, Gisela; Tyliszczak, Tolek; Rott, Karsten; Brueckl, Hubert; Reiss, Guenter; Neudecker, Ingo; Haug, Thomas; Buess, Matthias; Back, Christian H. [Max-Planck-Institut fuer Metallforschung, 70569 Stuttgart (Germany); Chemical Science Division, LBNL, Berkeley, California, 94720 (United States); Fakultaet fuer Physik, Universitaet Bielefeld, 33501 Bielefeld (Germany); Experimentelle Physik, Universitaet Regensburg, 93053 Regensburg (Germany)

2005-05-15

399

Magnetic resonance imaging of primary intracranial tumors: a review  

SciTech Connect

The experience in magnetic resonance (MR) imaging of primary intracranial neoplasia at University of California, San Francisco is reviewed. Seventy patients have been evaluated by MR and computerized tomography (CT). MR scans were performed using a multi-slice spin echo technique with a long pulse repetition time (TR = 2000 msec), and long echo sampling delay (TE = 56 msec). This method was most sensitive in differentiating normal gray and white matter and in detecting both cerebral edema and abnormal tissue with prolonged T/sub 2/ characteristics. More sensitive to slight alterations in normal tissue, MR may detect a focal lesion in cases in which CT shows only mass effect. Moreover, MR may demonstrate more thoroughly the extent of tumor infiltration and broaden the characterization of abnormal tissue. Posterior fossa and brainstem anatomy are invariably better depicted by MR. The major limitations of MR include its inability to detect foci of tumor calcification, demonstrate the severity of bone destruction, or reliably distinguish tumor nidus from surrounding edema.

Holland, B.A.; Brant-Zawadzki, M.; Norman, D.; Newton, T.H.

1985-02-01

400

Functional magnetic resonance imaging of autism spectrum disorders.  

PubMed

This review presents an overview of functional magnetic resonance imaging findings in autism spectrum disorders (ASDS), although there is considerable heterogeneity with respect to results across studies, common themes have emerged, including: (i) hypoactivation in nodes of the "social brain" during social processing tasks, including regions within the prefrontal cortex, the posterior superior temporal sulcus, the amygdala, and the fusiform gyrus; (ii) aberrant frontostriatal activation during cognitive control tasks relevant to restricted and repetitive behaviors and interests, including regions within the dorsal prefrontal cortex and the basal ganglia; (iii) differential lateralization and activation of language processing and production regions during communication tasks; (iv) anomalous mesolimbic responses to social and nonsocial rewards; (v) task-based long-range functional hypoconnectivity and short-range hyper-connectivity; and (vi) decreased anterior-posterior functional connectivity during resting states. These findings provide mechanistic accounts of ASD pathophysiology and suggest directions for future research aimed at elucidating etiologic models and developing rationally derived and targeted treatments. PMID:23226956

Dichter, Gabriel S

2012-09-01

401

Imaging surface plasmon resonance for multiplex microassay sensing of mycotoxins.  

PubMed

A prototype imaging surface plasmon resonance-based multiplex microimmunoassay for mycotoxins is described. A microarray of mycotoxin-protein conjugates was fabricated using a continuous flow microspotter device. A competitive inhibition immunoassay format was developed for the simultaneous detection of deoxynivalenol (DON) and zearalenone (ZEN), using a single sensor chip. Initial in-house validation showed limits of detection of 21 and 17 ng/mL for DON and 16 and 10 ng/mL for ZEN in extracts, which corresponds to 84 and 68 ?g/kg for DON and 64 and 40 ?g/kg for ZEN in maize and wheat samples, respectively. Finally, the results were critically compared with data obtained from liquid chromatography-mass spectrometry confirmatory analysis method and found to be in good agreement. The described multiplex immunoassay for the rapid screening of several mycotoxins meets European Union regulatory limits and represents a robust platform for mycotoxin analysis in food and feed samples. PMID:21484244

Dorokhin, Denis; Haasnoot, Willem; Franssen, Maurice C R; Zuilhof, Han; Nielen, Michel W F

2011-07-01

402

Genetically encoded reporters for hyperpolarized xenon magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

Magnetic resonance imaging (MRI) enables high-resolution non-invasive observation of the anatomy and function of intact organisms. However, previous MRI reporters of key biological processes tied to gene expression have been limited by the inherently low molecular sensitivity of conventional 1H MRI. This limitation could be overcome through the use of hyperpolarized nuclei, such as in the noble gas xenon, but previous reporters acting on such nuclei have been synthetic. Here, we introduce the first genetically encoded reporters for hyperpolarized 129Xe MRI. These expressible reporters are based on gas vesicles (GVs), gas-binding protein nanostructures expressed by certain buoyant microorganisms. We show that GVs are capable of chemical exchange saturation transfer interactions with xenon, which enables chemically amplified GV detection at picomolar concentrations (a 100- to 10,000-fold improvement over comparable constructs for 1H MRI). We demonstrate the use of GVs as heterologously expressed indicators of gene expression and chemically targeted exogenous labels in MRI experiments performed on living cells.

Shapiro, Mikhail G.; Ramirez, R. Matthew; Sperling, Lindsay J.; Sun, George; Sun, Jinny; Pines, Alexander; Schaffer, David V.; Bajaj, Vikram S.

2014-07-01

403

Segmentation and classification of dynamic breast magnetic resonance image data  

NASA Astrophysics Data System (ADS)

An application of an unsupervised self-organizing neural network-the minimal free energy vector quantization neural network-is reported for the detection and characterization of breast lesions in dynamic contrast-enhanced magnetic resonance imaging (MRI). This technique enables the extraction of spatial and temporal features of dynamic MRI data stemming from patients with confirmed lesion diagnosis. By revealing regional properties of contrast-agent uptake, characterized by subtle differences of signal amplitude and dynamics, this method provides both a set of prototypical time series and a corresponding set of cluster assignment maps, which further provides a segmentation with regard to identification and regional subclassification of pathological breast tissue lesions. We present three different segmentation methods for the evaluation of signal intensity time courses for the differential diagnosis of enhancing lesions in breast MRI. Starting from the conventional methodology, we proceed by introducing the separate concepts of threshold segmentation and cluster analysis based on the minimal free energy vector quantization neural network, and in the last step by combining those two concepts. The results suggest that the minimal free energy vector quantization neural network has the potential to increase the diagnostic accuracy of MRI mammography by improving sensitivity without reduction of specificity.

Wismüller, Axel; Meyer-Bäse, Anke; Lange, Oliver; Schlossbauer, Thomas; Kallergi, Maria; Reiser, Maximilian; Leinsinger, Gerda

2006-01-01

404

Pilocytic astrocytoma presenting with atypical features on magnetic resonance imaging.  

PubMed

Pilocytic astrocytoma, which is classified as a grade I astrocytic tumor by the World Health Organization, is the most common type of glioma in children and young adults. Pilocytic astrocytoma generally appears as a well-circumscribed, contrast-enhancing lesion, frequently with cystic components on magnetic resonance imaging (MRI). However, it has been reported that the MRI appearance of pilocytic astrocytoma may be similar to that of high-grade gliomas in some cases. We here report on 6 cases of pilocytic astrocytoma with atypical MRI findings, including small cyst formation, heterogeneously enhancing tumor nodules, irregularly enhancing tumor nodules, and enhancing tumor nodules with internal hemorrhage. All tumors were successfully resected, and the histological diagnoses were pilocytic astrocytoma. When the tumor is located near a cerebral cistern or ventricle, the risk of leptomeningeal dissemination is increased. Furthermore, partial resection has also been associated with a higher risk of recurrence and leptomeningeal dissemination. To date, all but one patient are alive and recurrence-free. Because the preoperative diagnosis influences the decision on the extent of resection and because of the high risk of leptomeningeal dissemination associated with these tumors, careful and correct diagnosis by MRI is important. PMID:25454397

Nakano, Yoshiteru; Yamamoto, Junkoh; Takahashi, Mayu; Soejima, Yoshiteru; Akiba, Daisuke; Kitagawa, Takehiro; Ueta, Kunihiro; Miyaoka, Ryo; Umemura, Takeru; Nishizawa, Shigeru

2014-11-01

405

Achromatic synesthesias - a functional magnetic resonance imaging study.  

PubMed

Grapheme-color synesthetes experience consistent, automatic and idiosyncratic colors associated with specific letters and numbers. Frequently, these specific associations exhibit achromatic synesthetic qualities (e.g. white, black or gray). In this study, we have investigated for the first time the neural basis of achromatic synesthesias, their relationship to chromatic synesthesias and the achromatic congruency effect in order to understand not only synesthetic color but also other components of the synesthetic experience. To achieve this aim, functional magnetic resonance imaging experiments were performed in a group of associator grapheme-color synesthetes and matched controls who were stimulated with real chromatic and achromatic stimuli (Mondrians), and with letters and numbers that elicited different types of grapheme-color synesthesias (i.e. chromatic and achromatic inducers which elicited chromatic but also achromatic synesthesias, as well as congruent and incongruent ones). The information derived from the analysis of Mondrians and chromatic/achromatic synesthesias suggests that real and synesthetic colors/achromaticity do not fully share neural mechanisms. The whole-brain analysis of BOLD signals in response to the complete set of synesthetic inducers revealed that the functional peculiarities of the synesthetic brain are distributed, and reflect different components of the synesthetic experience: a perceptual component, an (attentional) feature binding component, and an emotional component. Additionally, the inclusion of achromatic experiences has provided new evidence in favor of the emotional binding theory, a line of interpretation which constitutes a bridge between grapheme-color synesthesia and other developmental modalities of the phenomenon. PMID:24845620

Melero, H; Ríos-Lago, M; Peña-Melián, A; Álvarez-Linera, J

2014-09-01

406

Functional magnetic resonance imaging of autism spectrum disorders  

PubMed Central

This review presents an overview of functional magnetic resonance imaging findings in autism spectrum disorders (ASDs), Although there is considerable heterogeneity with respect to results across studies, common themes have emerged, including: (i) hypoactivation in nodes of the “social brain” during social processing tasks, including regions within the prefrontal cortex, the posterior superior temporal sulcus, the amygdala, and the fusiform gyrus; (ii) aberrant frontostriatal activation during cognitive control tasks relevant to restricted and repetitive behaviors and interests, including regions within the dorsal prefrontal cortex and the basal ganglia; (iii) differential lateralization and activation of language processing and production regions during communication tasks; (iv) anomalous mesolimbic responses to social and nonsocial rewards; (v) task-based long-range functional hypoconnectivity and short-range hyper-connectivity; and (vi) decreased anterior-posterior functional connectivity during resting states. These findings provide mechanistic accounts of ASD pathophysiology and suggest directions for future research aimed at elucidating etiologic models and developing rationally derived and targeted treatments. PMID:23226956

Dichter, Gabriel S.

2012-01-01

407

Model-based 3-D segmentation of multiple sclerosis lesions in magnetic resonance brain images  

Microsoft Academic Search

Human investigators instinctively segment medical images into their anatomical components, drawing upon prior knowledge of anatomy to overcome image artifacts, noise, and lack of tissue contrast. The authors describe: 1) the development and use of a brain tissue probability model for the segmentation of multiple sclerosis (MS) lesions in magnetic resonance (MR) brain images, and 2) an empirical comparison of

Micheline Kamber; Rajjan Shinghal; D. L. Collins; Gordon S. Francis; Alan C. Evans

1995-01-01

408

Magnetic resonance imaging of laser polarized liquid xenon C. H. Tseng,1,2  

E-print Network

Magnetic resonance imaging of laser polarized liquid xenon C. H. Tseng,1,2 R. W. Mair,1 G. P. Wong liquid xenon, and image exchange between the liquid and vapor phases. The exceptionally large averaging. Applications may include imaging of density equilibration and convective flow near xenon's liquid

Walsworth, Ronald L.

409

Computational problems in magnetic resonance imaging Tuomo Valkonen, University of Cambridge  

E-print Network

pathologies. Figure: Illustration of the DTI process. Left-to-right: 1. DWI images, 2. colour-coded tensors, 3 (Uni-Graz), and F. Knoll (TU Graz). Diffusion tensor imaging [7, 8] Diffusion-weighted MRI measuresComputational problems in magnetic resonance imaging Tuomo Valkonen, University of Cambridge Joint

Edinburgh, University of

410

An Interventional Magnetic Resonance Imaging Technique for the Molecular Characterization of Intraprostatic  

E-print Network

an important role in cancer care and clinical research if the molecular processes that underlie the image data, molecular imaging, interventional MRI, prostate cancer, micro- array analysis. Introduction Dynamic contrastAn Interventional Magnetic Resonance Imaging Technique for the Molecular Characterization

Whitcomb, Louis L.

411

Role of Magnetic Resonance Imaging in the Clinical Diagnosis of the Temporomandibular Joint  

Microsoft Academic Search

Temporomandibular joint (TMJ) abnormalities cannot be reliably assessed by a clinical examination. Magnetic resonance imaging (MRI) may depict joint abnormalities not seen with any other imaging method and thus is the best method to make a diagnostic assessment of the TMJ status. In patients with temporomandibular joint disorder (TMD) referred for diagnostic imaging the predominant TMJ finding is internal derangement

Tore A. Larheim

2005-01-01

412

TUMOR SEGMENTATION FROM MAGNETIC RESONANCE IMAGING BY LEARNING VIA ONE-CLASS SUPPORT VECTOR MACHINE  

E-print Network

TUMOR SEGMENTATION FROM MAGNETIC RESONANCE IMAGING BY LEARNING VIA ONE-CLASS SUPPORT VECTOR MACHINE Center Singapore General Hospital, Singapore Email: gdrcfh@sgh.com.sg ABSTRACT In image segmentation, one viewpoints with application on medical image segmentation. For that, a novel and user-friendly tumor

Paris-Sud XI, Université de

413

Morphology and distribution of liquid inclusions in young sea ice as imaged by magnetic resonance  

NASA Astrophysics Data System (ADS)

In order to determine the morphology and distribution of liquid inclusions in young sea ice, magnetic resonance imaging of an 18 cm sea ice core was done using a Siemens 3T TIM TRIO human scanner. The sample was stored at about -20 °C until the beginning of a constructive interference steady state gradient echo sequence which lasted four and a half min. Here we present the first three-dimensional reconstruction of a brine drainage channel network in young sea ice using magnetic resonance imaging. The magnetic resonance image sequence data presented here clearly illustrate that brine drainage channels are established relatively quickly during ice formation, and indicates the amount and location of vertical and horizontal fluid permeability in young sea ice. A simple analysis of the image sequence reveals that magnetic resonance imaging is useful in describing the vertical profile of liquid fraction that compares well to volumes calculated for similar sea ice temperatures. Future work in this vein may include three-dimensional magnetic resonance scans of sea ice cores at in situ temperatures using different magnetic resonance sequences in order to improve the observation of inclusions, though this will necessitate both access to a scanner and the construction of a cooling system compatible with a magnetic resonance imager.

Galley, R. J.; Else, B. G. T.; Geilfus, N.-X.; Hare, A. A.; Isleifson, D.; Ryner, L.; Barber, D. G.; Rysgaard, S.

2013-10-01

414

Magnetic resonance imaging for adaptive cobalt tomotherapy: A proposal  

PubMed Central

Magnetic resonance imaging (MRI) provides excellent soft tissue contrast for oncology applications. We propose to combine a MRI scanner with a helical tomotherapy (HT) system to enable daily target imaging for improved conformal radiation dose delivery to a patient. HT uses an intensity-modulated fan-beam that revolves around a patient, while the patient slowly advances through the plane of rotation, yielding a helical beam trajectory. Since the use of a linear accelerator to produce radiation may be incompatible with the pulsed radiofrequency and the high and pulsed magnetic fields required for MRI, it is proposed that a radioactive Cobalt-60 (60Co) source be used instead to provide the radiation. An open low field (0.25 T) MRI system is proposed where the tomotherapy ring gantry is located between two sets of Helmholtz coils that can generate a sufficiently homogenous main magnetic field. It is shown that the two major challenges with the design, namely acceptable radiation dose rate (and therefore treatment duration) and moving parts in strong magnetic field, can be addressed. The high dose rate desired for helical tomotherapy delivery can be achieved using two radiation sources of 220TBq (6000Ci) each on a ring gantry with a source to axis-of-rotation distance of 75 cm. In addition to this, a dual row multi-leaf collimator (MLC) system with 15 mm leaf width at isocentre and relatively large fan beam widths between 15 and 30 mm per row shall be employed. In this configuration, the unit would be well-suited for most pelvic radiotherapy applications where the soft tissue contrast of MRI will be particularly beneficial. Non-magnetic MRI compatible materials must be used for the rotating gantry. Tungsten, which is non-magnetic, can be used for primary collimation of the fan-beam as well as for the MLC, which allows intensity modulated radiation delivery. We propose to employ a low magnetic Cobalt compound, sycoporite (CoS) for the Cobalt source material itself. Rotational delivery is less susceptible to problems related to the use of a low energy megavoltage photon source while the helical delivery reduces the negative impact of the relatively large penumbra inherent in the use of Cobalt sources for radiotherapy. On the other hand, the use of a 60Co source ensures constant dose rate with gantry rotation and makes dose calculation in a magnetic field as easy as the range of secondary electrons is limited. The MR-integrated Cobalt tomotherapy unit, dubbed ‘MiCoTo,’ uses two independent physical principles for image acquisition and treatment delivery. It would offer excellent target definition and will allow following target motion during treatment using fast imaging techniques thus providing the best possible input for adaptive radiotherapy. As an additional bonus, quality assurance of the radiation delivery can be performed in situ using radiation sensitive gels imaged by MRI. PMID:21206640

Kron, Tomas; Eyles, David; John, Schreiner L; Battista, Jerry

2006-01-01

415

Three-dimensional display from cross-sectional tomographic images: an application to magnetic resonance imaging.  

PubMed

A system has been developed to facilitate three-dimensional visualizations of tomographic image data. Tomographic techniques yield parallel planes of data at discrete locations; thus, a series of images comprises a three-dimensional database. From this database, a system has been developed to perform three-dimensional calculations, measurements, and display. The system consists of a conventional two-dimensional video monitor, a digitizing tablet for user interaction and region-of-interest (ROI) definition, application-oriented computational software, and an image display system for true three-dimensional database visualization. The three-dimensional display makes use of a varifocal mirror system with vector graphics capability. Through the use of specialized contouring software, we illustrate the utility of this system in the specific examples of displays prepared from magnetic resonance (MR) images of the brain and carotid arteries. It can be concluded that this system will provide valuable diagnostic and physiologic information that will provide added insight into normal and abnormal structure and its relationship to function. PMID:18230439

Kennedy, D N; Nelson, A C

1987-01-01

416

Image segmentation by EM-based adaptive pulse coupled neural networks in brain magnetic resonance imaging.  

PubMed

We propose an automatic hybrid image segmentation model that integrates the statistical expectation maximization (EM) model and the spatial pulse coupled neural network (PCNN) for brain magnetic resonance imaging (MRI) segmentation. In addition, an adaptive mechanism is developed to fine tune the PCNN parameters. The EM model serves two functions: evaluation of the PCNN image segmentation and adaptive adjustment of the PCNN parameters for optimal segmentation. To evaluate the performance of the adaptive EM-PCNN, we use it to segment MR brain image into gray matter (GM), white matter (WM) and cerebrospinal fluid (CSF). The performance of the adaptive EM-PCNN is compared with that of the non-adaptive EM-PCNN, EM, and Bias Corrected Fuzzy C-Means (BCFCM) algorithms. The result is four sets of boundaries for the GM and the brain parenchyma (GM+WM), the two regions of most interest in medical research and clinical applications. Each set of boundaries is compared with the golden standard to evaluate the segmentation performance. The adaptive EM-PCNN significantly outperforms the non-adaptive EM-PCNN, EM, and BCFCM algorithms in gray mater segmentation. In brain parenchyma segmentation, the adaptive EM-PCNN significantly outperforms the BCFCM only. However, the adaptive EM-PCNN is better than the non-adaptive EM-PCNN and EM on average. We conclude that of the three approaches, the adaptive EM-PCNN yields the best results for gray matter and brain parenchyma segmentation. PMID:20042313

Fu, J C; Chen, C C; Chai, J W; Wong, S T C; Li, I C

2010-06-01

417

Magnetic Resonance Imaging of the Newborn Brain: Automatic Segmentation of Brain Images into 50 Anatomical Regions  

PubMed Central

We studied methods for the automatic segmentation of neonatal and developing brain images into 50 anatomical regions, utilizing a new set of manually segmented magnetic resonance (MR) images from 5 term-born and 15 preterm infants imaged at term corrected age called ALBERTs. Two methods were compared: individual registrations with label propagation and fusion; and template based registration with propagation of a maximum probability neonatal ALBERT (MPNA). In both cases we evaluated the performance of different neonatal atlases and MPNA, and the approaches were compared with the manual segmentations by means of the Dice overlap coefficient. Dice values, averaged across regions, were 0.81±0.02 using label propagation and fusion for the preterm population, and 0.81±0.02 using the single registration of a MPNA for the term population. Segmentations of 36 further unsegmented target images of developing brains yielded visibly high-quality results. This registration approach allows the rapid construction of automatically labeled age-specific brain atlases for neonates and the developing brain. PMID:23565180

Gousias, Ioannis S.; Hammers, Alexander; Counsell, Serena J.; Srinivasan, Latha; Rutherford, Mary A.; Heckemann, Rolf A.; Hajnal, Jo V.; Rueckert, Daniel; Edwards, A. David

2013-01-01

418

Imaging of stroke: a comparison between X-ray fluorescence and magnetic resonance imaging methods  

PubMed Central

A dual imaging approach, combining magnetic resonance imaging to localize lesions and synchrotron rapid scanning X-ray fluorescence (XRF) mapping to localize and quantify calcium, iron and zinc was used to examine one case of recent stroke with hemorrhage and two cases of ischemia 3 and 7 years before death with the latter showing superficial necrosis. In hemorrhagic lesions, more Fe is found accompanied with less Zn. In chronic ischemic lesions, Fe, Zn and Ca are lower indicating that these elements are removed as the normal tissue dies and scar tissue forms. Both susceptibility and T2* maps were calculated to visualize iron in hemorrhages and validated by XRF Ca and Fe maps. The former was superior for imaging iron in hemorrhagic transformation and necrosis but did not capture ischemic lesions. In contrast, T2* could not differentiate Ca from Fe in necrotic tissue but did capture ischemic lesions, complementing the susceptibility mapping. The spatial localization, accurate quantitative data and elemental differentiation shown here could also be valuable for imaging other brain tissue damage with abnormal Ca and Fe content. PMID:22789844

Zheng, Weili; Haacke, E. Mark; Webb, Samuel M.; Nichol, Helen

2013-01-01

419

In vivo magnetic resonance imaging and semiautomated image analysis extend the brain phenotype for cdf\\/cdf mice  

Microsoft Academic Search

Magnetic resonance imaging and computer image analysis in human clinical studies effectively identify abnormal neuroanatomy in disease populations. As more mouse models of neurological disorders are discovered, such an approach may prove useful for translational studies. Here, we demonstrate the effectiveness of a similar strategy for mouse neuroscience studies by phenotyping mice with the cerebellar deficient folia (cdf) mutation. Using

N. A. Bock; N Kovacevic; T V Lipina; J C Roder; S L Ackerman; R M Henkelman

2006-01-01

420

Imaging the pain of low back pain: functional magnetic resonance imaging in combination with monitoring subjective pain perception  

E-print Network

Imaging the pain of low back pain: functional magnetic resonance imaging in combination to generate predictor waveforms with which related brain activity can be identi®ed. Chronic low back pain-leg raising procedure is performed to exacerbate the back pain. In the normal volunteer, fMRI scans were done

Apkarian, A. Vania

421

HST.583 Functional Magnetic Resonance Imaging: Data Acquisition and Analysis, Fall 2006  

E-print Network

This team taught, multidisciplinary course covers the fundamentals of magnetic resonance imaging relevant to the conduct and interpretation of human brain mapping studies. The challenges inherent in advancing our knowledge ...

Gollub, Randy L.

422

Phase-based regional oxygen metabolism in magnetic resonance imaging at high field  

E-print Network

Venous oxygen saturation (Yv) in cerebral veins and the cerebral metabolic rate of oxygen (CMRO?) are important indicators for brain function and disease. Phase-susceptibility measurements in magnetic resonance imaging ...

Fan, Audrey Peiwen

2010-01-01

423

Multimodal neuroimaging with simultaneous electroencephalogram and high-field functional magnetic resonance imaging  

E-print Network

Simultaneous recording of electroencephalogram (EEG) and functional magnetic resonance imaging (tMRI) is an important emerging tool in functional neuroimaging with the potential to reveal new mechanisms for brain function ...

Purdon, Patrick L. (Patrick Lee), 1974-

2005-01-01

424

Individual Differences in Sentence Comprehension: A Functional Magnetic Resonance Imaging Investigation  

E-print Network

. & INTRODUCTION Reading comprehension is a complex skill in which there are systematic individual differencesIndividual Differences in Sentence Comprehension: A Functional Magnetic Resonance Imaging Just Abstract & Language comprehension is neurally underpinned by a net- work of collaborating cortical

425

One-pot synthesis of magnetic nanoclusters enabling atherosclerosis-targeted magnetic resonance imaging  

PubMed Central

In this study, dextran-encrusted magnetic nanoclusters (DMNCs) were synthesized using a one-pot solution phase method for detection of atherosclerosis by magnetic resonance imaging. Pyrenyl dextran was used as a surfactant because of its electron-stabilizing effect and its amphiphilic nature, rendering the DMNCs stable and water-dispersible. The DMNCs were 65.6±4.3 nm, had a narrow size distribution, and were superparamagnetic with a high magnetization value of 60.1 emu/g. Further, they showed biocompatibility and high cellular uptake efficiency, as indicated by a strong interaction between dextran and macrophages. In vivo magnetic resonance imaging demonstrated the ability of DMNCs to act as an efficient magnetic resonance imaging contrast agent capable of targeted detection of atherosclerosis. In view of these findings, it is concluded that DMNCs can be used as magnetic resonance imaging contrast agents to detect inflammatory disease. PMID:24904209

Kukreja, Aastha; Lim, Eun-Kyung; Kang, Byunghoon; Choi, Yuna; Lee, Taeksu; Suh, Jin-Suck; Huh, Yong-Min; Haam, Seungjoo

2014-01-01

426

A 16-Channel Receive Array Insert for Magnetic Resonance Imaging of the Breast at 7T  

E-print Network

Breast cancer is the second leading cause of cancer death among females in the United States. Magnetic resonance imaging (MRI) has emerged as a powerful tool for detecting and evaluating the disease, with notable advantages over other modalities...

By, Samantha

2014-04-01

427

Multilayered nanocoatings incorporating superparamagnetic nanoparticles for tracking of pancreatic islet transplants with magnetic resonance imaging.  

PubMed

A novel strategy for delivering functionalised superparamagnetic iron oxide nanoparticles to the outer surface of pancreatic islet grafts, using chemically modified polymeric nanolayers, has been developed for tracking of engrafted pancreatic islets by magnetic resonance imaging. PMID:23846395

Wang, Yang; Blanco-Andujar, Cristina; Zhi, Zheng-liang; So, Po-Wah; Thanh, Nguyen Thi Kim; Pickup, John C

2013-08-21

428

Anatomical Brain Magnetic Resonance Imaging of Typically Developing Children and Adolescents  

ERIC Educational Resources Information Center

Methodological issues relevant to magnetic resonance imaging studies of brain anatomy are discussed along with the findings on the neuroanatomic changes during childhood and adolescence. The development of the brain is also discussed.

Giedd, Jay N.; Lalonde, Francois M.; Celano, Mark J.; White, Samantha L.; Wallace, Gregory L.; Lee, Nancy R.; Lenroot, Rhoshel K.

2009-01-01

429

Brain functional magnetic resonance imaging response to glucose and fructose infusions in humans  

Technology Transfer Automated Retrieval System (TEKTRAN)

Objective: In animals, intracerebroventricular glucose and fructose have opposing effects on appetite and weight regulation. In humans, functional brain magnetic resonance imaging (fMRI) studies during carbohydrate ingestion suggest that glucose may regulate HT signaling but are potentially confoun...

430

Magnetic resonance spectroscopic imaging with 2D spectroscopy for the detection of brain metabolites  

E-print Network

While magnetic resonance imaging (MRI) derives its signal from protons in water, additional biochemical compounds are detectable in vivo within the proton spectrum. The detection and mapping of these much weaker signals ...

Kok, Trina

2012-01-01

431

Transmit field pattern control for high field magnetic resonance imaging with integrated RF current sources  

E-print Network

The primary design criterion for RF transmit coils for MRI is uniform transverse magnetic (B1) field. Currently, most high frequency transmit coils are designed as periodic, symmetric structures that are resonant at the imaging frequency...

Kurpad, Krishna Nagaraj

2005-11-01

432

J-Substitution Algorithm in Magnetic Resonance Electrical Impedance Tomography (MREIT): Phantom Experiments for Static Resistivity Images  

Microsoft Academic Search

Recently, a new static resistivity image reconstruction algorithm is proposed utilizing internal current density data obtained by magnetic resonance current density imaging technique. This new imaging method is called magnetic resonance electrical impedance tomography (MREIT). The derivation and performance of J-substitution algorithm in MREIT have been reported as a new accurate and high-resolution static impedance imaging technique via computer simulation

Hyan Soo Khang; Byung Il Lee; Suk Hoon Oh; Eung Je Woo; Soo Yeol Lee; Min Hyoung Cho; Ohin Kwon; Jeong-rock Yoon; Jin Keun Seo

2002-01-01

433

Can Images Obtained With High Field Strength Magnetic Resonance Imaging Reduce Contouring Variability of the Prostate?  

SciTech Connect

Purpose: The objective of this study is to determine whether there is less contouring variability of the prostate using higher-strength magnetic resonance images (MRI) compared with standard MRI and computed tomography (CT). Methods and Materials: Forty patients treated with prostate brachytherapy were accrued to a prospective study that included the acquisition of 1.5-T MR and CT images at specified time points. A subset of 10 patients had additional 3.0-T MR images acquired at the same time as their 1.5-T MR scans. Images from each of these patients were contoured by 5 radiation oncologists, with a random subset of patients repeated to quantify intraobserver contouring variability. To minimize bias in contouring the prostate, the image sets were placed in folders in a random order with all identifiers removed from the images. Results: Although there was less interobserver contouring variability in the overall prostate volumes in 1.5-T MRI compared with 3.0-T MRI (p < 0.01), there was no significant differences in contouring variability in the different regions of the prostate between 1.5-T MRI and 3.0-T MRI. MRI demonstrated significantly less interobserver contouring variability in both 1.5-T and 3.0-T compared with CT in overall prostate volumes (p < 0.01, p = 0.01), with the greatest benefits being appreciated in the base of the prostate. Overall, there was less intraobserver contouring variability than interobserver contouring variability for all of the measurements analyzed. Conclusions: Use of 3.0-T MRI does not demonstrate a significant improvement in contouring variability compared with 1.5-T MRI, although both magnetic strengths demonstrated less contouring variability compared with CT.

Usmani, Nawaid, E-mail: Nawaid.Usmani@albertahealthservices.ca [Department of Radiation Oncology, Cross Cancer Institute, Edmonton, AB (Canada); Department of Oncology, University of Alberta, Edmonton, AB (Canada); Sloboda, Ron [Department of Oncology, University of Alberta, Edmonton, AB (Canada); Department of Medical Physics, Cross Cancer Institute, Edmonton, AB (Canada); Kamal, Wafa [Department of Radiation Oncology, Cross Cancer Institute, Edmonton, AB (Canada); Ghosh, Sunita [Department of Oncology, University of Alberta, Edmonton, AB (Canada); Department of Experimental Oncology, Cross Cancer Institute, Edmonton, AB (Canada); Pervez, Nadeem; Pedersen, John; Yee, Don; Danielson, Brita; Murtha, Albert; Amanie, John [Department of Radiation Oncology, Cross Cancer Institute, Edmonton, AB (Canada); Department of Oncology, University of Alberta, Edmonton, AB (Canada); Monajemi, Tara [Department of Medical Physics, Cross Cancer Institute, Edmonton, AB (Canada)

2011-07-01

434

A Survey of Prostate Segmentation Methodologies in Ultrasound, Magnetic Resonance and Computed Tomography Images  

E-print Network

A Survey of Prostate Segmentation Methodologies in Ultrasound, Magnetic Resonance and Computed Resonance Center, Joan Maragall 26, 17002 Girona, Spain Abstract Prostate segmentation is a challenging task-calcifications and imaging artifacts like shadow poses serious challenges to accurate prostate segmentation in transrectal

Boyer, Edmond

435

Near field imaging in microwave regime using double layer split-ring resonator based metamaterial  

E-print Network

Near field imaging in microwave regime using double layer split-ring resonator based metamaterial K Engineering, Bilkent University, 06-800 Ankara, Turkey A planar metamaterial structure consisting of two with subwavelength resolution. The source frequency is swept through the resonance gap of the metamaterial layers

Ozbay, Ekmel

436

Large Sample Group Independent Component Analysis of Functional Magnetic Resonance Imaging Using Anatomical  

E-print Network

of functional magnetic resonance imaging (fMRI) signals that is capable of revealing connected brain systems to perform group-level analyses on datasets consisting of hundreds of scan sessions by combining the results fMRI; group ICA; bagging; clustering; bootstrap I. INTRODUCTION Functional magnetic resonance

Yuille, Alan L.

437

Surface Plasmon Resonance Imaging Using a High Numerical Aperture Microscope Objective  

E-print Network

Surface Plasmon Resonance Imaging Using a High Numerical Aperture Microscope Objective Bo Huang-5080 We designed, constructed, and tested a surface plasmon resonance (SPR) microscope using a high numerical aperture objective from a commercially available inverted optical microscope. Such a configuration

Zare, Richard N.

438

Comparison of imaging with sub-wavelength resolution in the canalization and resonant tunnelling regimes  

Microsoft Academic Search

We compare the properties of sub-wavelength imaging in the visible wavelength range for metal-dielectric multilayers operating in the canalization and the resonant tunnelling regimes. The analysis is based on the transfer matrix method and time domain simulations. We show that point spread functions for the first two resonances in the canalization regime are approximately Gaussian in shape. Material losses suppress

R. Kotynski; T. Stefaniuk

2009-01-01

439

Cardiac magnetic resonance imaging safety following percutaneous coronary intervention.  

PubMed

In the first 8 weeks after percutaneous coronary intervention (PCI), possible negative interactions exist between the cardiac magnetic resonance (CMR) imaging environment and the weakly ferromagnetic material in coronary stents. There are circumstances when CMR would be indicated shortly following PCI, such as acute myocardial infarction (AMI). The purpose of this study is to demonstrate CMR safety shortly following stent PCI in AMI patients. We performed a retrospective analysis of safety data in AMI patients with recently placed coronary artery stents enrolled in a multi-center phase II trial for gadoversetamide. Patients underwent 1.5 T CMR within 16 days of PCI. Vital signs (blood pressure, heart rate, respiratory rate, and body temperature) and ECGs were taken pre-CMR, 1, 2, and 24 h post-CMR. Any major adverse cardiac event (MACE) or other serious adverse events in the first 24 h after MRI were recorded. There were 258 stents in 211 AMI patients. The mean delay to CMR following PCI was 6.5 ± 4 days, with 62 patients (29 %) receiving CMR within 3 days and 132 patients (63 %) within 1 week. Patients showed no significant vital sign changes following CMR. Ten patients (4.7 %) showed mild, transient ECG changes. Within the 24-h follow-up group, 4 patients (1.9 %) had moderate to severe events, including chest pain (1) and elevated cardiac enzymes (1), resolving in 24 h; heart failure (1) and ischemic stroke (1). There were no deaths. This study demonstrates fewer MACE in AMI patients undergoing 1.5 T CMR within 16 days of stent placement in comparison to post-stent event rate reported in the literature. This study adds to the CMR after stent PCI safety profile suggested by previous studies and is the largest and first study that uses multicenter data to assess stent safety following CMR examination. PMID:23624930

Curtis, Jason W; Lesniak, Donna C; Wible, James H; Woodard, Pamela K

2013-10-01

440

Compact low field magnetic resonance imaging magnet: Design and optimization  

NASA Astrophysics Data System (ADS)

Magnetic resonance imaging (MRI) is performed with a very large instrument that allows the patient to be inserted into a region of uniform magnetic field. The field is generated either by an electromagnet (resistive or superconductive) or by a permanent magnet. Electromagnets are designed as air cored solenoids of cylindrical symmetry, with an inner bore of 80-100 cm in diameter. In clinical analysis of peripheral regions of the body (legs, arms, foot, knee, etc.) it would be better to adopt much less expensive magnets leaving the most expensive instruments to applications that require the insertion of the patient in the magnet (head, thorax, abdomen, etc.). These "dedicated" apparati could be smaller and based on resistive magnets that are manufactured and operated at very low cost, particularly if they utilize an iron yoke to reduce power requirements. In order to obtain good field uniformity without the use of a set of shimming coils, we propose both particular construction of a dedicated magnet, using four independently controlled pairs of coils, and an optimization-based strategy for computing, a posteriori, the optimal current values. The optimization phase could be viewed as a low-cost shimming procedure for obtaining the desired magnetic field configuration. Some experimental measurements, confirming the effectiveness of the proposed approach (construction and optimization), have also been reported. In particular, it has been shown that the adoption of the proposed optimization based strategy has allowed the achievement of good uniformity of the magnetic field in about one fourth of the magnet length and about one half of its bore. On the basis of the good experimental results, the dedicated magnet can be used for MRI of peripheral regions of the body and for animal experimentation at very low cost.

Sciandrone, M.; Placidi, G.; Testa, L.; Sotgiu, A.

2000-03-01

441

Incidental extraspinal findings on magnetic resonance imaging of intervertebral discs  

PubMed Central

Introduction We aimed to evaluate pathological extraspinal findings and congenital anomalies/anatomical variations that were incidentally detected on the magnetic resonance imaging (MRI) scans of intervertebral discs, to find the frequencies of these incidental findings, and to emphasise the clinical importance of them. Material and methods A retrospective study including 1031 consecutive patients (730 females and 301 males, with a median age of 46 years) was conducted by evaluating a total of 1106 MRI examinations of intervertebral discs. Examinations were performed with a 1.5 T MRI unit. Incidental findings were classified as pathological findings and congenital anomalies/anatomical variations. Results The percentages of incidental extraspinal pathological findings and congenital anomalies/anatomical variations were 16.6% (95% confidence interval (CI): 14.4–18.8) and 3.7% (95% CI: 2.6–4.3), respectively. The percentage of incidental extraspinal pathological findings on cervical spinal MRI was 25.7% (95% CI: 20.1–31.7), thyroid nodules being the most common incidental findings. On thoracic spinal MRI (n = 19), inferior pole thyroid nodules were demonstrated as incidental extraspinal pathological findings, with a percentage of 10.5% (95% CI: 9.6–11.5). On lumbar spinal MRI, incidental pathological findings were detected with a percentage of 14.2% (95% CI: 11.9–16.6), while the percentage of congenital anomalies/anatomical variations was 4.8% (95% CI: 3.4–6.3). Eventually, 6.5% (95% CI: 2.6–9.4) of all cases with incidental extraspinal pathological findings underwent surgery. Conclusions On MRI examination of intervertebral discs, paying attention to incidentally detected pathological extraspinal findings and congenital anomalies/anatomical variations is very important due to the fact that they can alter the treatment of the patient or affect the patient's life. PMID:25276162

Ayaz, Umit Yasar; Turanl?, Sevim; Saltas, Hakan; Karabacak, Osman Raif; Damar, Cagr?; Hekimoglu, Baki

2014-01-01

442

Assessment of mitral regurgitation by magnetic resonance imaging.  

PubMed

To evaluate the potential of magnetic resonance imaging (MRI) in detection and quantification of mitral regurgitation, 26 pts. with echocardiographically or angiographically documented mitral regurgitation were examined using a 0.5 Tesla superconducting magnet. In each patient a multislice-multiphase study in a sagittal-coronal double angulated projection (four-chamber view equivalent) was performed to assess left and right ventricular volumes, ejection fraction and regurgitant fraction. Additionally a blood flow sensitive cine-study (fast field echo: FFE) was done to visualize direction and area of regurgitant jet. MRI data were compared with quantitative and quantitative assessment of mitral regurgitation by angiography, 2D echocardiography, Doppler sonography and color flow mapping. Using the FFE mode MRI was able to detect the regurgitant jet as a typical signal loss within the left atrium in all patients. The ratio of regurgitant jet area/left atrium area as determined by MRI showed a correlation with a comparable ratio from color Doppler sonography of R = 0.87 (p less than 0.001). There was also good agreement in semiquantitative grading of mitral regurgitation between MRI and angiography (R = 0.77, p less than 0.001). The determination of left and right ventricular stroke volume allowed the calculation of the regurgitant fraction, which showed a correlation with invasively determined regurgitation fraction of R = 0.84 (p less than 0.001). These data provide additional information that MRI may be useful as a noninvasive technique to detect and quantify mitral regurgitation. PMID:2630843

Glogar, D; Globits, S; Neuhold, A; Mayr, H

1989-01-01

443

Conventional magnetic resonance imaging features in patients with tropical spastic paraparesis  

Microsoft Academic Search

Conventional brain and spinal cord magnetic resonance images were performed in 21 patients with human T-cell lymphotropic\\u000a virus (HTLV)-1 associated myelopathy\\/tropical spastic paraparesis, to assess the role of conventional magnetic resonance imaging\\u000a (MRI) in the disease diagnosis. These patients had no other central nervous system conditions or related risk factors at the\\u000a time of tropical spastic paraparesis diagnosis. Eleven (52.4%)

Francesca Bagnato; John A. Butman; Carlos A. Mora; Shiva Gupta; Yoshima Yamano; Talin A. Tasciyan; Jeffrey M. Solomon; Waldyr J. Santos; Roger D. Stone; Henry F. McFarland; Steven Jacobson

2005-01-01

444

Functional magnetic resonance imaging of symptom provocation in obsessive-compulsive disorder  

Microsoft Academic Search

BACKGROUND: The new technique of functional magnetic resonance imaging was used to investigate the mediating neuroanatomy of obsessive-compulsive disorder symptoms. METHODS: Ten patients with obsessive-compulsive disorder and 5 normal subjects were studied via functional magnetic resonance imaging during control and provoked conditions. Data analysis entailed parametric and nonparametric statistical mapping. RESULTS: Statistical maps (nonparametric; P < 10(-3)) showed activation for

H. C. Breiter; S. L. Rauch; K. K. Kwong; J. R. Baker; R. M. Weisskoff; D. N. Kennedy; A. D. Kendrick; T. L. Davis; A. Jiang; M. S. Cohen; C. E. Stern; J. W. Belliveau; L. Baer; R. L. O'Sullivan; C. R. Savage; M. A. Jenike; B. R. Rosen

1996-01-01

445

Ductal carcinoma in situ: detection, diagnosis, and characterization with magnetic resonance imaging.  

PubMed

Ductal carcinoma in situ (DCIS) is a preinvasive malignancy that currently accounts for over 20% of newly diagnosed breast cancers in the US. This article reviews how clinical magnetic resonance imaging methods are being implemented for the detection, diagnosis and characterization of DCIS. Research strategies that are being pursued to help realize the full potential for magnetic resonance imaging to improve the outcomes of patients diagnosed with DCIS are discussed. PMID:21782121

Jansen, Sanaz A

2011-08-01

446

Multisection 1 H Magnetic Resonance Spectroscopic Imaging Assessment of Glioma Response to Chemotherapy  

Microsoft Academic Search

Summary  This study evaluated the role of proton magnetic resonance spectroscopic imaging (1H MRSI) in assessing the response of low-grade brain tumors to a chemotherapy-only treatment regimen. Specifically, it was\\u000a of interest to assess if 1H MRSI could detect early tumor response to therapy prior to magnetic resonance imaging (MRI) changes, and to establish which\\u000a spectral markers were sensitive to regional

Casilda Balmaceda; Dana Critchell; Xiangling Mao; Kenneth Cheung; Susan Pannullo; Robert L. DeLaPaz; Dikoma C. Shungu

2006-01-01

447

Detecting tumor responses to treatment using hyperpolarized 13C magnetic resonance spectroscopic imaging  

E-print Network

ORAL PRESENTATION Open Access Detecting tumor responses to treatment using hyperpolarized 13C magnetic resonance spectroscopic imaging Kevin M Brindle From 16th International Charles Heidelberger Symposium on Cancer Research Coimbra, Portugal. 26... - labeled bicarbonate. Nature 2008, 453:940-943. doi:10.1038/nrc2289 Cite this article as: Brindle: Detecting tumor responses to treatment using hyperpolarized 13C magnetic resonance spectroscopic imaging. BMC Proceedings 2010 4(Suppl 2):O24. Correspondence...

2010-09-24

448

Pulmonary ventilation imaged by magnetic resonance: at the doorstep of clinical application  

Microsoft Academic Search

ABSTRACT: Over the past few years, magnetic resonance imaging (MRI) has emerged,as an important instrument for functional ventilation imaging. The aim of this review,is to summarize,established clinical methods,and,emerging,techniques,for research and clinical arenas. Before the advent of MRI, chest radiography and computed tomography (CT) dominated morphological lung imaging, while functional ventilation imaging was accomplished with scintigraphy. Initially, MRI was not used

H. U. Kauczor; X. J. Chen; E. J. R. van Beek; W. G. Schreiber