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Sample records for artery image quality

  1. High-quality 3-D coronary artery imaging on an interventional C-arm x-ray system

    SciTech Connect

    Hansis, Eberhard; Carroll, John D.; Schaefer, Dirk; Doessel, Olaf; Grass, Michael

    2010-04-15

    Purpose: Three-dimensional (3-D) reconstruction of the coronary arteries during a cardiac catheter-based intervention can be performed from a C-arm based rotational x-ray angiography sequence. It can support the diagnosis of coronary artery disease, treatment planning, and intervention guidance. 3-D reconstruction also enables quantitative vessel analysis, including vessel dynamics from a time-series of reconstructions. Methods: The strong angular undersampling and motion effects present in gated cardiac reconstruction necessitate the development of special reconstruction methods. This contribution presents a fully automatic method for creating high-quality coronary artery reconstructions. It employs a sparseness-prior based iterative reconstruction technique in combination with projection-based motion compensation. Results: The method is tested on a dynamic software phantom, assessing reconstruction accuracy with respect to vessel radii and attenuation coefficients. Reconstructions from clinical cases are presented, displaying high contrast, sharpness, and level of detail. Conclusions: The presented method enables high-quality 3-D coronary artery imaging on an interventional C-arm system.

  2. Coronary artery stent (image)

    MedlinePLUS

    ... with a balloon catheter and expands when the balloon is inflated. The stent is then left there to help keep the artery open. ... with a balloon catheter and expands when the balloon is inflated. The stent is then left there to help keep the artery open.

  3. Ultrasonic Imaging Of Deep Arteries

    NASA Technical Reports Server (NTRS)

    Rooney, James A.; Heyser, Richard C.; Lecroissette, Dennis H.

    1990-01-01

    Swept-frequency sound replaces pulsed sound. Ultrasonic medical instrument produces images of peripheral and coronary arteries with resolutions higher and at depths greater than attainable by previous ultrasonic systems. Time-delay-spectrometry imager includes scanning, image-processing, and displaying equipment. It sweeps in frequency from 0 to 10 MHz in 20 ms, pauses for 5 ms, and repeats sweep. Intended for use in noninvasive detection and measurement of atherosclerotic lesions.

  4. Optimised Computational Functional Imaging for Arteries

    E-print Network

    Nicoud, Franck

    Optimised Computational Functional Imaging for Arteries Ramiro Moreno1 , Ming Chau3 , Shirod Jeetoo of the Optimised Computational Func- tional Imaging for Arteries (OCFIA) program is to introduce high of the complex velocity distribution and biomechanical load on the arterial wall. Nevertheless there is not doubt

  5. Photoacoustic imaging of carotid artery atherosclerosis

    NASA Astrophysics Data System (ADS)

    Kruizinga, Pieter; van der Steen, Antonius F. W.; de Jong, Nico; Springeling, Geert; Robertus, Jan Lukas; van der Lugt, Aad; van Soest, Gijs

    2014-11-01

    We introduce a method for photoacoustic imaging of the carotid artery, tailored toward detection of lipid-rich atherosclerotic lesions. A common human carotid artery was obtained at autopsy, embedded in a neck mimicking phantom and imaged with a multimodality imaging system using interstitial illumination. Light was delivered through a 1.25-mm-diameter optical probe that can be placed in the pharynx, allowing the carotid artery to be illuminated from within the body. Ultrasound imaging and photoacoustic signal detection is achieved by an external 8-MHz linear array coupled to an ultrasound imaging system. Spectroscopic analysis of photoacoustic images obtained in the wavelength range from 1130 to 1250 nm revealed plaque-specific lipid accumulation in the collagen structure of the artery wall. These spectroscopic findings were confirmed by histology.

  6. Troubleshooting Arterial-Phase MR Images of Gadoxetate Disodium-Enhanced Liver

    PubMed Central

    Huh, Jimi; Yeh, Benjamin M.; Lee, Seung Soo; Kim, Kyoung Won; Wu, En-Haw; Wang, Z. Jane; Zhao, Li-qin; Chang, Wei Chou

    2015-01-01

    Gadoxetate disodium is a widely used magnetic resonance (MR) contrast agent for liver MR imaging, and it provides both dynamic and hepatobiliary phase images. However, acquiring optimal arterial phase images at liver MR using gadoxetate disodium is more challenging than using conventional extracellular MR contrast agent because of the small volume administered, the gadolinium content of the agent, and the common occurrence of transient severe motion. In this article, we identify the challenges in obtaining high-quality arterial-phase images of gadoxetate disodium-enhanced liver MR imaging and present strategies for optimizing arterial-phase imaging based on the thorough review of recent research in this field. PMID:26576109

  7. Quantitative Amyloid Imaging Using Image-Derived Arterial Input Function

    PubMed Central

    Su, Yi; Blazey, Tyler M.; Snyder, Abraham Z.; Raichle, Marcus E.; Hornbeck, Russ C.; Aldea, Patricia; Morris, John C.; Benzinger, Tammie L. S.

    2015-01-01

    Amyloid PET imaging is an indispensable tool widely used in the investigation, diagnosis and monitoring of Alzheimer’s disease (AD). Currently, a reference region based approach is used as the mainstream quantification technique for amyloid imaging. This approach assumes the reference region is amyloid free and has the same tracer influx and washout kinetics as the regions of interest. However, this assumption may not always be valid. The goal of this work is to evaluate an amyloid imaging quantification technique that uses arterial region of interest as the reference to avoid potential bias caused by specific binding in the reference region. 21 participants, age 58 and up, underwent Pittsburgh compound B (PiB) PET imaging and MR imaging including a time-of-flight (TOF) MR angiography (MRA) scan and a structural scan. FreeSurfer based regional analysis was performed to quantify PiB PET data. Arterial input function was estimated based on coregistered TOF MRA using a modeling based technique. Regional distribution volume (VT) was calculated using Logan graphical analysis with estimated arterial input function. Kinetic modeling was also performed using the estimated arterial input function as a way to evaluate PiB binding (DVRkinetic) without a reference region. As a comparison, Logan graphical analysis was also performed with cerebellar cortex as reference to obtain DVRREF. Excellent agreement was observed between the two distribution volume ratio measurements (r>0.89, ICC>0.80). The estimated cerebellum VT was in line with literature reported values and the variability of cerebellum VT in the control group was comparable to reported variability using arterial sampling data. This study suggests that image-based arterial input function is a viable approach to quantify amyloid imaging data, without the need of arterial sampling or a reference region. This technique can be a valuable tool for amyloid imaging, particularly in population where reference normalization may not be accurate. PMID:25849581

  8. Social image quality

    NASA Astrophysics Data System (ADS)

    Qiu, Guoping; Kheiri, Ahmed

    2011-01-01

    Current subjective image quality assessments have been developed in the laboratory environments, under controlledconditions, and are dependent on the participation of limited numbers of observers. In this research, with the help of Web 2.0 and social media technology, a new method for building a subjective image quality metric has been developed where the observers are the Internet users. A website with a simple user interface that enables Internet users from anywhere at any time to vote for a better quality version of a pair of the same image has been constructed. Users' votes are recorded and used to rank the images according to their perceived visual qualities. We have developed three rank aggregation algorithms to process the recorded pair comparison data, the first uses a naive approach, the second employs a Condorcet method, and the third uses the Dykstra's extension of Bradley-Terry method. The website has been collecting data for about three months and has accumulated over 10,000 votes at the time of writing this paper. Results show that the Internet and its allied technologies such as crowdsourcing offer a promising new paradigm for image and video quality assessment where hundreds of thousands of Internet users can contribute to building more robust image quality metrics. We have made Internet user generated social image quality (SIQ) data of a public image database available online (http://www.hdri.cs.nott.ac.uk/siq/) to provide the image quality research community with a new source of ground truth data. The website continues to collect votes and will include more public image databases and will also be extended to include videos to collect social video quality (SVQ) data. All data will be public available on the website in due course.

  9. Magnetic resonance imaging of coronary artery occlusions in the navigator technique.

    PubMed

    Wittlinger, Thomas; Voigtländer, Thomas; Rohr, Martin; Meyer, Jürgen; Thelen, Martin; Kreitner, Karl Friedrich; Kalden, Peter

    2002-06-01

    Non-invasive assessment of coronary arteries is possible with magnetic resonance imaging (MRI). Respiratory gated MR coronary angiography is a new imaging technique that permits reconstruction of the coronary arteries based on a three-dimensional (3D) data set obtained from the free-breathing patient. In this study, respiratory gated MR angiography (MRA) was performed to assess coronary artery occlusions. MRI was performed in 25 patients who had been referred for conventional coronary angiography because of suspected coronary artery disease. Coronary artery occlusion was evaluated in the proximal and middle vessel segments after multiplanar coronary reconstruction of the MR images. Five patients were excluded from the study; in the remaining 20 patients 120 coronary artery segments were analyzed. Good image quality could be obtained for 85% of the segments. Eighteen of the 24 occlusions were confirmed by MRI, the overall sensitivity was 75% and the specificity was 100%. The best results were found in the proximal left anterior descending (LAD) and descending parts of the right coronary artery (RCA), where all occlusions were confirmed. These results showed that coronary artery occlusions can be detected in the proximal and middle LAD and RCA using 3D respiratory gated MRA. Further technical improvements, especially in spatial resolution, are necessary before MRA can become a reliable diagnostic tool in the non-invasive evaluation of coronary arteries. PMID:12123312

  10. Coronary artery balloon angioplasty - series (image)

    MedlinePLUS

    ... muscle (the coronary arteries) can be narrowed or blocked by this accumulation. If the narrowing is small, ... is a minimally invasive procedure to open up blocked coronary arteries, allowing blood to circulate unobstructed to ...

  11. Thermal Imaging of the Superficial Temporal Artery: An Arterial Pulse Recovery Model

    E-print Network

    Farag, Aly A.

    been greatly advanced by Pavlidis et al. [10], [9] who applied thermal imagery for the measurementThermal Imaging of the Superficial Temporal Artery: An Arterial Pulse Recovery Model Sergey Y) using passive thermal Infra Red (IR) sensors. The proposed ap- proach has a physical and physiological

  12. Different Imaging Strategies in Patients With Possible Basilar Artery Occlusion

    PubMed Central

    Beyer, Sebastian E.; Hunink, Myriam G.; Schöberl, Florian; von Baumgarten, Louisa; Petersen, Steffen E.; Dichgans, Martin; Janssen, Hendrik; Ertl-Wagner, Birgit; Reiser, Maximilian F.

    2015-01-01

    Background and Purpose— This study evaluated the cost-effectiveness of different noninvasive imaging strategies in patients with possible basilar artery occlusion. Methods— A Markov decision analytic model was used to evaluate long-term outcomes resulting from strategies using computed tomographic angiography (CTA), magnetic resonance imaging, nonenhanced CT, or duplex ultrasound with intravenous (IV) thrombolysis being administered after positive findings. The analysis was performed from the societal perspective based on US recommendations. Input parameters were derived from the literature. Costs were obtained from United States costing sources and published literature. Outcomes were lifetime costs, quality-adjusted life-years (QALYs), incremental cost-effectiveness ratios, and net monetary benefits, with a willingness-to-pay threshold of $80 000 per QALY. The strategy with the highest net monetary benefit was considered the most cost-effective. Extensive deterministic and probabilistic sensitivity analyses were performed to explore the effect of varying parameter values. Results— In the reference case analysis, CTA dominated all other imaging strategies. CTA yielded 0.02 QALYs more than magnetic resonance imaging and 0.04 QALYs more than duplex ultrasound followed by CTA. At a willingness-to-pay threshold of $80 000 per QALY, CTA yielded the highest net monetary benefits. The probability that CTA is cost-effective was 96% at a willingness-to-pay threshold of $80 000/QALY. Sensitivity analyses showed that duplex ultrasound was cost-effective only for a prior probability of ?0.02 and that these results were only minimally influenced by duplex ultrasound sensitivity and specificity. Nonenhanced CT and magnetic resonance imaging never became the most cost-effective strategy. Conclusions— Our results suggest that CTA in patients with possible basilar artery occlusion is cost-effective. PMID:26022634

  13. Variation in Arterial Inflow Temperature: A Regional Quality Improvement Project

    PubMed Central

    Warren, Craig S.; DeFoe, Gordon R.; Groom, Robert C.; Pieroni, John W.; Groski, Candace S.; Morse, Catherine B.; Connors, Ellen M.; Lataille, Peter J.; Ross, Cathy S.; Likosky, Donald S.

    2011-01-01

    Abstract: Peer-reviewed evidence (Class IIa, Level B) suggests that arterial blood temperature should be limited to 37°C during cardiopulmonary bypass. We implemented a regional quality improvement initiative to reduce regional variability in our performance around this recommendation at four northern New England medical centers between January 2006 and June 2010. Cardiovascular perfusionists at four medical centers collaborated by conference calls regarding blood temperature management. Evidence from the recommendations were reviewed at each center, and strategies to prevent hyperthermia and to improve performance on this quality measure were discussed. Centers submitted data concerning highest arterial blood temperatures among all isolated coronary artery bypass grafting procedures between 2006 through June 2010. Scope and focus of local practice changes were at the discretion of each center. The timing of each center’s quality improvement initiatives was recorded, and adherence to thresholds of 37°C and 37.5°C were analyzed. Data were collected prospectively through our regional per-fusion registry. Data were available for 4909 procedures (1645 before interventions, 3264 after interventions). Prior to the quality improvement interventions, 90% of procedures had elevated arterial line temperatures (37°C or more), and afterwards it was 69% (p < .001) for an absolute difference of 21%. Prior to the intervention, 53% of procedures had temperatures beyond a threshold of 37.5°C versus 19% subsequent to interventions, for an absolute difference of 34% (p < .001). This regional effort to reduce patient exposure to elevated arterial line temperatures resulted in a significant sustained reduction in high arterial outflow temperatures at three of the four centers. A regional registry provides a means for assessing performance against evidence-based recommendations, and evaluating short and long-term success of quality improvement initiatives. PMID:21848173

  14. Vessel Wall Imaging of the Intracranial and Cervical Carotid Arteries

    PubMed Central

    Choi, Young Jun; Jung, Seung Chai; Lee, Deok Hee

    2015-01-01

    Vessel wall imaging can depict the morphologies of atherosclerotic plaques, arterial walls, and surrounding structures in the intracranial and cervical carotid arteries beyond the simple luminal changes that can be observed with traditional luminal evaluation. Differentiating vulnerable from stable plaques and characterizing atherosclerotic plaques are vital parts of the early diagnosis, prevention, and treatment of stroke and the neurological adverse effects of atherosclerosis. Various techniques for vessel wall imaging have been developed and introduced to differentiate and analyze atherosclerotic plaques in the cervical carotid artery. High-resolution magnetic resonance imaging (HR-MRI) is the most important and popular vessel wall imaging technique for directly evaluating the vascular wall and intracranial artery disease. Intracranial artery atherosclerosis, dissection, moyamoya disease, vasculitis, and reversible cerebral vasoconstriction syndrome can also be diagnosed and differentiated by using HR-MRI. Here, we review the radiologic features of intracranial artery disease and cervical carotid artery atherosclerosis on HR-MRI and various other vessel wall imaging techniques (e.g., ultrasound, computed tomography, magnetic resonance, and positron emission tomography-computed tomography). PMID:26437991

  15. Spatially adaptive image quality metrics for perceptual image quality assessment

    NASA Astrophysics Data System (ADS)

    Fliegel, Karel

    2009-08-01

    The problem of objective image quality assessment has been known for couple of decades but with emerging multimedia technologies it becomes very important. This paper presents an approach to predict perceived quality of compressed images while incorporating real visual attention coordinates. Information about the visual attention is not usually taken into account in models for image quality assessment. Impact of the region of interest on estimation accuracy of a simple image quality metric has been investigated in our previous papers. The gaze coordinates were calculated using calibrated electro-oculogram records of human observers while watching a number of test images. This paper further investigates this idea using data from more observers. Obtained mean opinion scores of perceived image quality and eye tracking data were used to verify potential improvement of assessment accuracy for a simple image quality metric.

  16. A new imaging technique based on resonance for arterial vessels

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoming; Fatemi, Mostafa; Greenleaf, James F.

    2003-04-01

    Vibro-acoustography is a new noncontact imaging method based on the radiation force of ultrasound. We extend this technique for imaging of arterial vessels based on vibration resonance. The arterial vessel is excited remotely by ultrasound at a resonant frequency, at which the vibration of the vessel as well as its transmission to the body surface are large enough to be measured. By scanning the ultrasound beam across the vessel plane and measuring the vibration at one single point on the body or vessel surface, an image of the interior artery can be mapped. Theory is developed that predicts the measured velocity is proportional to the value of the mode shape at resonance. Experimental studies were carried out on a silicone tube embedded in a cylindrical gel phantom of large radius, which simulates a large artery and the surrounding body. The fundamental frequency was measured at which the ultrasound transducer scanned across the tube plane with velocity measurement at one single point on the tube or on the phantom by laser. The images obtained show clearly the interior tube and the modal shape of the tube. The present technique offers a new imaging method for arterial vessels.

  17. Retinal Image Quality During Accommodation

    PubMed Central

    López-Gil, N.; Martin, J.; Liu, T.; Bradley, A.; Díaz-Muñoz, D.; Thibos, L.

    2013-01-01

    Purpose We asked if retinal image quality is maximum during accommodation, or sub-optimal due to accommodative error, when subjects perform an acuity task. Methods Subjects viewed a monochromatic (552nm), high-contrast letter target placed at various viewing distances. Wavefront aberrations of the accommodating eye were measured near the endpoint of an acuity staircase paradigm. Refractive state, defined as the optimum target vergence for maximising retinal image quality, was computed by through-focus wavefront analysis to find the power of the virtual correcting lens that maximizes visual Strehl ratio. Results Despite changes in ocular aberrations and pupil size during binocular viewing, retinal image quality and visual acuity typically remain high for all target vergences. When accommodative errors lead to sub-optimal retinal image quality, acuity and measured image quality both decline. However, the effect of accommodation errors of on visual acuity are mitigated by pupillary constriction associated with accommodation and binocular convergence and also to binocular summation of dissimilar retinal image blur. Under monocular viewing conditions some subjects displayed significant accommodative lag that reduced visual performance, an effect that was exacerbated by pharmacological dilation of the pupil. Conclusions Spurious measurement of accommodative error can be avoided when the image quality metric used to determine refractive state is compatible with the focusing criteria used by the visual system to control accommodation. Real focusing errors of the accommodating eye do not necessarily produce a reliably measurable loss of image quality or clinically significant loss of visual performance, probably because of increased depth-of-focus due to pupil constriction. When retinal image quality is close to maximum achievable (given the eye’s higher-order aberrations), acuity is also near maximum. A combination of accommodative lag, reduced image quality, and reduced visual function may be a useful sign for diagnosing functionally-significant accommodative errors indicating the need for therapeutic intervention. PMID:23786386

  18. Image Enhancement, Image Quality, and Noise

    NASA Technical Reports Server (NTRS)

    Rahman, Zia-ur; Jobson, Daniel J.; Woodell, Glenn A.; Hines, Glenn D.

    2005-01-01

    The Multiscale Retinex With Color Restoration (MSRCR) is a non-linear image enhancement algorithm that provides simultaneous dynamic range compression, color constancy and rendition. The overall impact is to brighten up areas of poor contrast/lightness but not at the expense of saturating areas of good contrast/brightness. The downside is that with the poor signal-to-noise ratio that most image acquisition devices have in dark regions, noise can also be greatly enhanced thus affecting overall image quality. In this paper, we will discuss the impact of the MSRCR on the overall quality of an enhanced image as a function of the strength of shadows in an image, and as a function of the root-mean-square (RMS) signal-to-noise (SNR) ratio of the image.

  19. Quality assessment for hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Chen, Yuheng; Chen, Xinhua; Zhou, Jiankang; Shen, Weimin

    2014-11-01

    Image quality assessment is an essential value judgement approach for many applications. Multi & hyper spectral imaging has more judging essentials than grey scale or RGB imaging and its image quality assessment job has to cover up all-around evaluating factors. This paper presents an integrating spectral imaging quality assessment project, in which spectral-based, radiometric-based and spatial-based statistical behavior for three hyperspectral imagers are jointly executed. Spectral response function is worked out based on discrete illumination images and its spectral performance is deduced according to its FWHM and spectral excursion value. Radiometric response ability of different spectral channel under both on-ground and airborne imaging condition is judged by SNR computing based upon local RMS extraction and statistics method. Spatial response evaluation of the spectral imaging instrument is worked out by MTF computing with slanted edge analysis method. Reported pioneering systemic work in hyperspectral imaging quality assessment is carried out with the help of several domestic dominating work units, which not only has significance in the development of on-ground and in-orbit instrument performance evaluation technique but also takes on reference value for index demonstration and design optimization for instrument development.

  20. IEEE TRANSACTIONS ON MEDICAL IMAGING 1 Retinal artery-vein classification via topology

    E-print Network

    Tomasi, Carlo

    IEEE TRANSACTIONS ON MEDICAL IMAGING 1 Retinal artery-vein classification via topology estimation Abstract--We propose a novel, graph-theoretic framework for distinguishing arteries from veins in a fundus manifestation. Index Terms--artery-vein classification, medical imaging, graph theory, tree topology, image

  1. Arterial Perfusion Imaging-Defined Subvolume of Intrahepatic Cancer

    PubMed Central

    Wang, Hesheng; Farjam, Reza; Feng, Mary; Hussain, Hero; Ten Haken, Randall K.; Lawrence, Theodore S.; Cao, Yue

    2014-01-01

    Purpose To assess whether an increase in a subvolume of intrahepatic tumor with elevated arterial perfusion during radiation therapy (RT) predicts tumor progression post RT. Methods and Materials Twenty patients with unresectable intrahepatic cancers undergoing RT were enrolled in a prospective IRB-approved study. Dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) were performed prior to RT (pre-RT), after delivering ~60% of the planned dose (mid-RT) and one month after completion of RT to quantify hepatic arterial perfusion. The arterial perfusions of the tumors at pre-RT were clustered into low-normal and elevated perfusion by a fuzzy clustering-based method, and the tumor subvolumes with elevated arterial perfusion were extracted from the hepatic arterial perfusion images. The percentage changes in the tumor subvolumes and means of arterial perfusion over the tumors from pre-RT to mid-RT were evaluated for predicting tumor progression post-RT. Results Of the 24 tumors, 6 tumors in 5 patients progressed 5–21 months after RT completion. Neither tumor volumes nor means of tumor arterial perfusion at pre-RT were predictive of treatment outcome. The mean arterial perfusion over the tumors increased significantly at mid-RT in progressive tumors comparing to the responsive ones (p=0.006). From pre-RT to mid-RT, the responsive tumors had a decrease in the tumor subvolumes with elevated arterial perfusion (median: ?14%, range: ?75% – 65%), while the progressing tumors had an increase of the subvolumes (median: 57%, range: ?7% – 165%) (p=0.003). Receiver operating characteristic (ROC) analysis of the percentage change in the subvolume for predicting tumor progression post-RT had an area under the curve (AUC) of 0.90. Conclusion The increase in the subvolume of the intrahepatic tumor with elevated arterial perfusion during RT has the potential to be a predictor for tumor progression post-RT. The tumor subvolume could be a radiation boost candidate for response-driven adaptive RT. PMID:24613814

  2. The development and potential of acoustic radiation force impulse (ARFI) imaging for carotid artery plaque characterization.

    PubMed

    Allen, Jason D; Ham, Katherine L; Dumont, Douglas M; Sileshi, Bantayehu; Trahey, Gregg E; Dahl, Jeremy J

    2011-08-01

    Stroke is the third leading cause of death and long-term disability in the USA. Currently, surgical intervention decisions in asymptomatic patients are based upon the degree of carotid artery stenosis. While there is a clear benefit of endarterectomy for patients with severe (> 70%) stenosis, in those with high/moderate (50-69%) stenosis the evidence is less clear. Evidence suggests ischemic stroke is associated less with calcified and fibrous plaques than with those containing softer tissue, especially when accompanied by a thin fibrous cap. A reliable mechanism for the identification of individuals with atherosclerotic plaques which confer the highest risk for stroke is fundamental to the selection of patients for vascular interventions. Acoustic radiation force impulse (ARFI) imaging is a new ultrasonic-based imaging method that characterizes the mechanical properties of tissue by measuring displacement resulting from the application of acoustic radiation force. These displacements provide information about the local stiffness of tissue and can differentiate between soft and hard areas. Because arterial walls, soft tissue, atheromas, and calcifications have a wide range in their stiffness properties, they represent excellent candidates for ARFI imaging. We present information from early phantom experiments and excised human limb studies to in vivo carotid artery scans and provide evidence for the ability of ARFI to provide high-quality images which highlight mechanical differences in tissue stiffness not readily apparent in matched B-mode images. This allows ARFI to identify soft from hard plaques and differentiate characteristics associated with plaque vulnerability or stability. PMID:21447606

  3. Complex-Valued Analysis of Arterial Spin LabelingBased Functional Magnetic Resonance Imaging

    E-print Network

    Rowe, Daniel B.

    Complex-Valued Analysis of Arterial Spin Labeling­Based Functional Magnetic Resonance Imaging-dependent phase differences between tagged and control arterial spin labeling images are reported. A biophysical model is presented to explain the vascular origin of this difference. Arterial spin labeling data

  4. Analysis techniques for coronary arteries and cardiac function using advanced MRI and CT imaging

    E-print Network

    Greenaway, Alan

    Analysis techniques for coronary arteries and cardiac function using advanced MRI and CT imaging angiography is used to assess the coronary arteries due to its high spatial resolution, and MR is used by CT feasible, while new MR techniques increase the spatial resolution imaging the coronary arteries

  5. Label-free imaging of arterial cells and extracellular matrix using a multimodal CARS microscope

    E-print Network

    Cheng, Ji-Xin

    Label-free imaging of arterial cells and extracellular matrix using a multimodal CARS microscope carotid arteries. CARS signals arising from CH2-rich membranes allowed visualization of endothelial cells and smooth muscle cells of the arterial wall. Additionally, CARS microscopy allowed vibrational imaging

  6. Video and image quality

    NASA Astrophysics Data System (ADS)

    Aldridge, Jim

    1995-09-01

    This paper presents some of the results of a UK government research program into methods of improving the effectiveness of CCTV surveillance systems. The paper identifies the major components of video security systems and primary causes of unsatisfactory images. A method is outline for relating the picture detail limitations imposed by each system component on overall system performance. The paper also points out some possible difficulties arising from the use of emerging new technology.

  7. Landsat image data quality studies

    NASA Technical Reports Server (NTRS)

    Schueler, C. F.; Salomonson, V. V.

    1985-01-01

    Preliminary results of the Landsat-4 Image Data Quality Analysis (LIDQA) program to characterize the data obtained using the Thematic Mapper (TM) instrument on board the Landsat-4 and Landsat-5 satellites are reported. TM design specifications were compared to the obtained data with respect to four criteria, including spatial resolution; geometric fidelity; information content; and image relativity to Multispectral Scanner (MSS) data. The overall performance of the TM was rated excellent despite minor instabilities and radiometric anomalies in the data. Spatial performance of the TM exceeded design specifications in terms of both image sharpness and geometric accuracy, and the image utility of the TM data was at least twice as high as MSS data. The separability of alfalfa and sugar beet fields in a TM image is demonstrated.

  8. Structural Similarity Based Image Quality Assessment

    E-print Network

    Wang, Zhou

    Assessment quality. The goal of image quality assessment research is to design methods that quantifyStructural Similarity Based Image Quality Assessment Zhou Wang, Alan C. Bovik and Hamid R. Sheikh scene. The principle hypothesis of structural similarity based image quality assessment is that the HVS

  9. Intraindividual comparison of contrast-enhanced electron-beam computed tomography and navigator-echo-based magnetic resonance imaging for noninvasive coronary artery angiography.

    PubMed

    Nikolaou, Konstantin; Huber, Armin; Knez, Andreas; Becker, Christoph; Bruening, Roland; Reiser, Maximilian

    2002-07-01

    The aim of this study was to compare contrast-enhanced electron-beam computed tomography (EBCT) and navigator-echo-based MRI of the coronary arteries in the same patient population. Both methods were assessed for visualization of the coronary arteries and their diagnostic accuracy in identifying significant coronary artery stenoses compared with conventional coronary angiography. Twenty patients with known coronary artery disease were examined with both contrast-enhanced EBCT and a respiratory-gated MRI sequence. A grading system was used to evaluate the image quality. Sensitivity and specificity for the detection of significant coronary artery stenoses was evaluated compared with conventional coronary angiography. With EBCT, 89% of the main coronary arteries could be completely visualised in the proximal and middle segments; with MRI, 83% were visualised. With EBCT the sensitivities for identifying significant (>/=50%) stenoses in proximal and middle vessel segments were 75% in the main stem, 88% in the left anterior descending coronary artery, 75% in the left circumflex coronary artery, and 90% in the right coronary artery. Respective sensitivities for MRI angiograms were 75, 82, 75 and 80%. With both modalities a sufficient image quality of the main coronary arteries can be obtained in most cases. The diagnostic capability for detecting significant stenoses is comparable for both methods. PMID:12111056

  10. ECG-synchronized DSA exposure control: improved cervicothoracic image quality

    SciTech Connect

    Kelly, W.M.; Gould, R.; Norman, D.; Brant-Zawadzki, M.; Cox, L.

    1984-10-01

    An electrocardiogram (ECG)-synchronized x-ray exposure sequence was used to acquire digital subtraction angiographic (DSA) images during 13 arterial injection studies of the aortic arch or carotid bifurcations. These gated images were compared with matched ungated DSA images acquired using the same technical factors, contrast material volume, and patient positioning. Subjective assessments by five experienced observers of edge definition, vessel conspicuousness, and overall diagnostic quality showed overall preference for one of the two acquisition methods in 69% of cases studied. Of these, the ECG-synchronized exposure series were rated superior in 76%. These results, as well as the relatively simple and inexpensive modifications required, suggest that routine use of ECG exposure control can facilitate improved arterial DSA evaluations of suspected cervicothoracic vascular disease.

  11. Arterial Tortuosity Syndrome: An Approach through Imaging Perspective

    PubMed Central

    Bhat, Venkatraman

    2014-01-01

    This pictorial illustration demonstrates various aspects of arterial tortuosity syndrome (ATS) obtained predominantly from a multiple detector computed tomography (MDCT) examination of a patient. In addition, a comprehensive review of typical multi-modality imaging observations in patients with ATS is presented along with a description of a few imaging signs. Non-invasively obtained, conclusive information is required in patients with ATS in view of the fragile vascular structures involved. An amazing wealth of information can be obtained by reviewing the volumetric data sets of MDCT examination. In the context of incomplete clinical information or remote reading of radiographic examination with inadequate clinical details, ability to “image data mine” the hidden, unexplored information may be vastly useful. The role of MDCT as a single modality of evaluation in ATS is highlighted. PMID:25250193

  12. Comparative imaging study in ultrasound, MRI, CT, and DSA using a multimodality renal artery phantom

    SciTech Connect

    King, Deirdre M.; Fagan, Andrew J.; Moran, Carmel M.; Browne, Jacinta E.

    2011-02-15

    Purpose: A range of anatomically realistic multimodality renal artery phantoms consisting of vessels with varying degrees of stenosis was developed and evaluated using four imaging techniques currently used to detect renal artery stenosis (RAS). The spatial resolution required to visualize vascular geometry and the velocity detection performance required to adequately characterize blood flow in patients suffering from RAS are currently ill-defined, with the result that no one imaging modality has emerged as a gold standard technique for screening for this disease. Methods: The phantoms, which contained a range of stenosis values (0%, 30%, 50%, 70%, and 85%), were designed for use with ultrasound, magnetic resonance imaging, x-ray computed tomography, and x-ray digital subtraction angiography. The construction materials used were optimized with respect to their ultrasonic speed of sound and attenuation coefficient, MR relaxometry (T{sub 1},T{sub 2}) properties, and Hounsfield number/x-ray attenuation coefficient, with a design capable of tolerating high-pressure pulsatile flow. Fiducial targets, incorporated into the phantoms to allow for registration of images among modalities, were chosen to minimize geometric distortions. Results: High quality distortion-free images of the phantoms with good contrast between vessel lumen, fiducial markers, and background tissue to visualize all stenoses were obtained with each modality. Quantitative assessments of the grade of stenosis revealed significant discrepancies between modalities, with each underestimating the stenosis severity for the higher-stenosed phantoms (70% and 85%) by up to 14%, with the greatest discrepancy attributable to DSA. Conclusions: The design and construction of a range of anatomically realistic renal artery phantoms containing varying degrees of stenosis is described. Images obtained using the main four diagnostic techniques used to detect RAS were free from artifacts and exhibited adequate contrast to allow for quantitative measurements of the degree of stenosis in each phantom. Such multimodality phantoms may prove useful in evaluating current and emerging US, MRI, CT, and DSA technology.

  13. Contrast-enhanced ultrasound imaging of the vasa vasorum of carotid artery plaque

    PubMed Central

    Song, Ze-Zhou; Zhang, Yan-Ming

    2015-01-01

    The vasa vasorum of carotid artery plaque is a novel marker of accurately evaluating the vulnerability of carotid artery plaque, which was associated with symptomatic cerebrovascular and cardiovascular disease. The presence of ultrasound contrast agents in carotid artery plaque represents the presence of the vasa vasorum in carotid artery plaque because the ultrasound contrast agents are strict intravascular tracers. Therefore, contrast-enhanced ultrasound (CEUS) is a novel and safe imaging modality for evaluating the vasa vasorum in carotid artery plaque. However, there are some issues that needs to be assessed to embody fully the clinical utility of the vasa vasorum in carotid artery plaque with CEUS. PMID:26120382

  14. Augmented reality image guidance for minimally invasive coronary artery bypass

    NASA Astrophysics Data System (ADS)

    Figl, Michael; Rueckert, Daniel; Hawkes, David; Casula, Roberto; Hu, Mingxing; Pedro, Ose; Zhang, Dong Ping; Penney, Graeme; Bello, Fernando; Edwards, Philip

    2008-03-01

    We propose a novel system for image guidance in totally endoscopic coronary artery bypass (TECAB). A key requirement is the availability of 2D-3D registration techniques that can deal with non-rigid motion and deformation. Image guidance for TECAB is mainly required before the mechanical stabilization of the heart, thus the most dominant source of non-rigid deformation is the motion of the beating heart. To augment the images in the endoscope of the da Vinci robot, we have to find the transformation from the coordinate system of the preoperative imaging modality to the system of the endoscopic cameras. In a first step we build a 4D motion model of the beating heart. Intraoperatively we can use the ECG or video processing to determine the phase of the cardiac cycle. We can then take the heart surface from the motion model and register it to the stereo-endoscopic images of the da Vinci robot using 2D-3D registration methods. We are investigating robust feature tracking and intensity-based methods for this purpose. Images of the vessels available in the preoperative coordinate system can then be transformed to the camera system and projected into the calibrated endoscope view using two video mixers with chroma keying. It is hoped that the augmented view can improve the efficiency of TECAB surgery and reduce the conversion rate to more conventional procedures.

  15. Analysis of the Sensitivity and Specificity of Noninvasive Imaging Tests for the Diagnosis of Renal Artery Stenosis

    PubMed Central

    Borelli, Flavio Antonio de Oliveira; Pinto, Ibraim M. F.; Amodeo, Celso; Smanio, Paola E. P.; Kambara, Antonio M.; Petisco, Ana Claudia G.; Moreira, Samuel M.; Paiva, Ricardo Calil; Lopes, Hugo Belotti; Sousa, Amanda G. M. R.

    2013-01-01

    Background Aging and atherosclerosis are related to renovascular hypertension in elderly individuals. Regardless of comorbidities, renal artery stenosis is itself an important cause of cardiovascular morbidity and mortality. Objective To define the sensitivity, specificity, positive predictive value, and negative predictive value of noninvasive imaging tests used in the diagnosis of renal artery stenosis. Methods In a group of 61 patients recruited, 122 arteries were analized, thus permitting the definition of sensitivity, specificity, and the relative contribution of each imaging study performed (Doppler, scintigraphy and computed tomographic angiography in comparison to renal arteriography). Results The mean age was 65.43 years (standard deviation: 8.7). Of the variables related to the study population that were compared to arteriography, two correlated with renal artery stenosis, renal dysfunction and triglycerides. The median glomerular filtration rate was 52.8 mL/min/m2. Doppler showed sensitivity of 82.90%, specificity of 70%, a positive predictive value of 85% and negative predictive value of 66.70%. For tomography, sensitivity was 66.70%, specificity 80%, positive predictive value 87.50% and negative predictive value 55.20%. With these findings, we could identify the imaging tests that best detected stenosis. Conclusion Tomography and Doppler showed good quality and efficacy in the diagnosis of renal artery stenosis, with Doppler having the advantage of not requiring the use of contrast medium for the assessment of a disease that is common in diabetics and is associated with renal dysfunction and severe left ventricular dysfunction. PMID:24061685

  16. Cross-Sectional Imaging in a Case of Adventitial Cystic Disease of the Popliteal Artery

    SciTech Connect

    Ricci, Paolo; Panzetti, Claudio; Mastantuono, Marco; Bassetti, Erica; Iascone, Clemente; Ragonesi, Barbara; Bernucci, Paola; Gallo, Pietro; Rossi, Plinio

    1999-01-15

    Adventitial cystic disease of the popliteal artery is an unusual condition of uncertain etiology, in which a mucin-containing cyst forms in the wall of the artery and produces lower extremity claudication, typically in young and middle-aged men. A diagnosis of adventitial cystic disease of the popliteal artery was made preoperatively in a 47-year-old man by means of several imaging modalities, including angiography, magnetic resonance imaging, and ultrasound. The pathological findings confirmed the suggested diagnosis.

  17. In-vivo validation of fluorescence lifetime imaging (FLIm) of coronary arteries in swine

    NASA Astrophysics Data System (ADS)

    Bec, Julien; Ma, Dinglong; Yankelevich, Diego R.; Gorpas, Dimitris S.; Ferrier, William T.; Southard, Jeffrey; Marcu, Laura

    2015-02-01

    We report a scanning imaging system that enables high speed multispectral fluorescence lifetime imaging (FLIm) of coronary arteries. This system combines a custom low profile (3 Fr) imaging catheter using a 200 ?m core side viewing UV-grade silica fiber optic, an acquisition system able to measure fluorescence decays over four spectral bands at 20 kHz and a fast data analysis and display module. In vivo use of the system has been optimized, with particular emphasis on clearing blood from the optical pathway. A short acquisition time (5 seconds for a 20 mm long coronary segment) enabled data acquisition during a bolus saline solution injection through the 7 Fr catheter guide. The injection parameters were precisely controlled using a power injector and optimized to provide good image quality while limiting the bolus injection duration and volume (12 cc/s, 80 cc total volume). The ability of the system to acquire data in vivo was validated in healthy swine by imaging different sections of the left anterior descending (LAD) coronary. A stent coated with fluorescent markers was placed in the LAD and imaged, demonstrating the ability of the system to discriminate in vivo different fluorescent features and structures from the vessel background fluorescence using spectral and lifetime information. Intensity en face images over the four bands of the instrument were available within seconds whereas lifetime images were computed in 2 minutes, providing efficient feedback during the procedure. This successful demonstration of FLIm in coronaries enables future study of atherosclerotic cardiovascular diseases.

  18. Image guidance for robotic minimally invasive coronary artery bypass.

    PubMed

    Figl, Michael; Rueckert, Daniel; Hawkes, David; Casula, Roberto; Hu, Mingxing; Pedro, Ose; Zhang, Dong Ping; Penney, Graeme; Bello, Fernando; Edwards, Philip

    2010-01-01

    A novel system for image guidance in totally endoscopic coronary artery bypass (TECAB) is presented. Key requirement is the availability of 2D-3D registration techniques that can deal with non-rigid motion and deformation. Image guidance for TECAB is mainly required before the mechanical stabilisation of the heart, when the most dominant source of misregistration is the deformation and non-rigid motion of the heart. To augment the images in the endoscope of the da Vinci robot, we have to find the transformation from the coordinate system of the preoperative imaging modality to the system of the endoscopic cameras. In a first step we build a 4D motion model of the beating heart. Intraoperatively we can use the ECG or video processing to determine the phase of the cardiac cycle, as well as the heart and respiratory frequencies. We then take the heart surface from the motion model and register it to the stereo endoscopic images of the da Vinci robot resp. of a validation system using photo-consistency. To take advantage of the fact that there is a whole image sequence available for registration, we use the different phases together to get the registration. We found the similarity function to be much smoother when using more phases. This also showed promising behaviour in convergence tests. Images of the vessels available in the preoperative coordinate system can then be transformed to the camera system and projected into the calibrated endoscope view using two video mixers with chroma keying. It is hoped that the augmented view can improve the efficiency of TECAB surgery and reduce the conversion rate to more conventional procedures. PMID:19773147

  19. Univariant assessment of the quality of images

    NASA Astrophysics Data System (ADS)

    Jung, Mathieu; Leger, Dominique; Gazalet, Marc G.

    2002-07-01

    To evaluate the quality of images, most methods compare a degraded image to a perfect reference. Nevertheless in many cases, a reference does not exist. We propose an original univariant (i.e., without a reference) method based on the use of artificial neural networks. The principle behind it is to first teach a neural network to assess image quality using images taken from a pool of known examples, then use it to assess the quality of unknown images. The defects considered are compression artifacts, ringing, local singularities, etc. To simplify, only images with defects that are not mixed with one another were first used. Two illustrative examples are presented: assessment of the quality of JPEG compressed images and detection of local defects. The quality of the images is assessed without a reference and with error less than 6% - 7% compared to the bivariant method that was learned. Our method can even be used to model some very simple visual comportment.

  20. Blood vessel classification into arteries and veins in retinal images

    NASA Astrophysics Data System (ADS)

    Kondermann, Claudia; Kondermann, Daniel; Yan, Michelle

    2007-03-01

    The prevalence of diabetes is expected to increase dramatically in coming years; already today it accounts for a major proportion of the health care budget in many countries. Diabetic Retinopathy (DR), a micro vascular complication very often seen in diabetes patients, is the most common cause of visual loss in working age population of developed countries today. Since the possibility of slowing or even stopping the progress of this disease depends on the early detection of DR, an automatic analysis of fundus images would be of great help to the ophthalmologist due to the small size of the symptoms and the large number of patients. An important symptom for DR are abnormally wide veins leading to an unusually low ratio of the average diameter of arteries to veins (AVR). There are also other diseases like high blood pressure or diseases of the pancreas with one symptom being an abnormal AVR value. To determine it, a classification of vessels as arteries or veins is indispensable. As to our knowledge despite the importance there have only been two approaches to vessel classification yet. Therefore we propose an improved method. We compare two feature extraction methods and two classification methods based on support vector machines and neural networks. Given a hand-segmentation of vessels our approach achieves 95.32% correctly classified vessel pixels. This value decreases by 10% on average, if the result of a segmentation algorithm is used as basis for the classification.

  1. Successful serial imaging of the mouse cerebral arteries using conventional 3-T magnetic resonance imaging.

    PubMed

    Makino, Hiroshi; Hokamura, Kazuya; Natsume, Takahiro; Kimura, Tetsuro; Kamio, Yoshinobu; Magata, Yasuhiro; Namba, Hiroki; Katoh, Takasumi; Sato, Shigehito; Hashimoto, Tomoki; Umemura, Kazuo

    2015-09-01

    Serial imaging studies can be useful in characterizing the pathologic and physiologic remodeling of cerebral arteries in various mouse models. We tested the feasibility of using a readily available, conventional 3-T magnetic resonance imaging (MRI) to serially image cerebrovascular remodeling in mice. We utilized a mouse model of intracranial aneurysm as a mouse model of the dynamic, pathologic remodeling of cerebral arteries. Aneurysms were induced by hypertension and a single elastase injection into the cerebrospinal fluid. For the mouse cerebrovascular imaging, we used a conventional 3-T MRI system and a 40-mm saddle coil. We used non-enhanced magnetic resonance angiography (MRA) to detect intracranial aneurysm formation and T2-weighted imaging to detect aneurysmal subarachnoid hemorrhage. A serial MRI was conducted every 2 to 3 days. MRI detection of aneurysm formation and subarachnoid hemorrhage was compared against the postmortem inspection of the brain that was perfused with dye. The imaging times for the MRA and T2-weighted imaging were 3.7±0.5 minutes and 4.8±0.0 minutes, respectively. All aneurysms and subarachnoid hemorrhages were correctly identified by two masked observers on MRI. This MRI-based serial imaging technique was useful in detecting intracranial aneurysm formation and subarachnoid hemorrhage in mice. PMID:25920958

  2. Intravital live cell triggered imaging system reveals monocyte patrolling and macrophage migration in atherosclerotic arteries.

    PubMed

    McArdle, Sara; Chodaczek, Grzegorz; Ray, Nilanjan; Ley, Klaus

    2015-02-01

    Intravital multiphoton imaging of arteries is technically challenging because the artery expands with every heartbeat, causing severe motion artifacts. To study leukocyte activity in atherosclerosis, we developed the intravital live cell triggered imaging system (ILTIS). This system implements cardiac triggered acquisition as well as frame selection and image registration algorithms to produce stable movies of myeloid cell movement in atherosclerotic arteries in live mice. To minimize tissue damage, no mechanical stabilization is used and the artery is allowed to expand freely. ILTIS performs multicolor high frame-rate two-dimensional imaging and full-thickness three-dimensional imaging of beating arteries in live mice. The external carotid artery and its branches (superior thyroid and ascending pharyngeal arteries) were developed as a surgically accessible and reliable model of atherosclerosis. We use ILTIS to demonstrate Cx3cr1GFP monocytes patrolling the lumen of atherosclerotic arteries. Additionally, we developed a new reporter mouse (Apoe?/?Cx3cr1GFP/+Cd11cYFP) to image GFP+ and GFP+YFP + macrophages “dancing on the spot” and YFP+ macrophages migrating within intimal plaque. ILTIS will be helpful to answer pertinent open questions in the field, including monocyte recruitment and transmigration, macrophage and dendritic cell activity, and motion of other immune cells. PMID:25710308

  3. Intravital live cell triggered imaging system reveals monocyte patrolling and macrophage migration in atherosclerotic arteries

    NASA Astrophysics Data System (ADS)

    McArdle, Sara; Chodaczek, Grzegorz; Ray, Nilanjan; Ley, Klaus

    2015-02-01

    Intravital multiphoton imaging of arteries is technically challenging because the artery expands with every heartbeat, causing severe motion artifacts. To study leukocyte activity in atherosclerosis, we developed the intravital live cell triggered imaging system (ILTIS). This system implements cardiac triggered acquisition as well as frame selection and image registration algorithms to produce stable movies of myeloid cell movement in atherosclerotic arteries in live mice. To minimize tissue damage, no mechanical stabilization is used and the artery is allowed to expand freely. ILTIS performs multicolor high frame-rate two-dimensional imaging and full-thickness three-dimensional imaging of beating arteries in live mice. The external carotid artery and its branches (superior thyroid and ascending pharyngeal arteries) were developed as a surgically accessible and reliable model of atherosclerosis. We use ILTIS to demonstrate Cx3cr1GFP monocytes patrolling the lumen of atherosclerotic arteries. Additionally, we developed a new reporter mouse (Apoe-/-Cx3cr1GFP/+Cd11cYFP) to image GFP+ and GFP+YFP+ macrophages "dancing on the spot" and YFP+ macrophages migrating within intimal plaque. ILTIS will be helpful to answer pertinent open questions in the field, including monocyte recruitment and transmigration, macrophage and dendritic cell activity, and motion of other immune cells.

  4. Quality Metrics Evaluation of Hyperspectral Images

    NASA Astrophysics Data System (ADS)

    Singh, A. K.; Kumar, H. V.; Kadambi, G. R.; Kishore, J. K.; Shuttleworth, J.; Manikandan, J.

    2014-11-01

    In this paper, the quality metrics evaluation on hyperspectral images has been presented using k-means clustering and segmentation. After classification the assessment of similarity between original image and classified image is achieved by measurements of image quality parameters. Experiments were carried out on four different types of hyperspectral images. Aerial and spaceborne hyperspectral images with different spectral and geometric resolutions were considered for quality metrics evaluation. Principal Component Analysis (PCA) has been applied to reduce the dimensionality of hyperspectral data. PCA was ultimately used for reducing the number of effective variables resulting in reduced complexity in processing. In case of ordinary images a human viewer plays an important role in quality evaluation. Hyperspectral data are generally processed by automatic algorithms and hence cannot be viewed directly by human viewers. Therefore evaluating quality of classified image becomes even more significant. An elaborate comparison is made between k-means clustering and segmentation for all the images by taking Peak Signal-to-Noise Ratio (PSNR), Mean Square Error (MSE), Maximum Squared Error, ratio of squared norms called L2RAT and Entropy. First four parameters are calculated by comparing the quality of original hyperspectral image and classified image. Entropy is a measure of uncertainty or randomness which is calculated for classified image. Proposed methodology can be used for assessing the performance of any hyperspectral image classification techniques.

  5. Optical coherence tomography and hyperspectral imaging of vascular recovery in a model of peripheral arterial disease

    NASA Astrophysics Data System (ADS)

    Poole, Kristin M.; Sit, Wesley W.; Tucker-Schwartz, Jason M.; Duvall, Craig L.; Skala, Melissa C.

    2013-03-01

    Peripheral arterial disease (PAD) leads to an increased risk of myocardial infarction and stroke, increased mortality, and reduced quality of life. The mouse hind limb ischemia (HLI) model is the most commonly used system for studying the mechanisms of collateral vessel formation and for testing new PAD therapies, but there is a lack of techniques for acquiring physiologically-relevant, quantitative data intravitally in this model. In this work, non-invasive, quantitative optical imaging techniques were applied to the mouse HLI model over a time course. Optical coherence tomography (OCT) imaged changes in blood flow (Doppler OCT) and microvessel morphology (speckle variance OCT) through the skin of haired mice with high resolution. Hyperspectral imaging was also used to quantify blood oxygenation. In ischemic limbs, blood oxygenation in the footpad was substantially reduced after induction of ischemia followed by complete recovery by three weeks, consistent with standard measures. Three dimensional images of the vasculature distal to vessel occlusion acquired with speckle variance OCT revealed changes in OCT flow signal and vessel morphology. Taken together, OCT and hyperspectral imaging enable intravital acquisition of both functional and morphological data which fill critical gaps in understanding structure-function relationships that contribute to recovery in the mouse HLI model. Therefore, these optical imaging methods hold promise as tools for studying the mechanisms of vascular recovery and evaluating novel therapeutic treatments in preclinical studies.

  6. Cost-Effectiveness of Carotid Plaque MR Imaging as a Stroke Risk Stratification Tool in Asymptomatic Carotid Artery Stenosis.

    PubMed

    Gupta, Ajay; Mushlin, Alvin I; Kamel, Hooman; Navi, Babak B; Pandya, Ankur

    2015-12-01

    Purpose To evaluate the cost-effectiveness of a decision-making rule based on the magnetic resonance (MR) imaging assessment of intraplaque hemorrhage (IPH) in patients with asymptomatic carotid artery stenosis. Materials and Methods Two competing stroke prevention strategies were compared: (a) an intensive medical therapy-based management strategy versus (b) an imaging-based strategy in which the subset of patients with asymptomatic carotid artery stenosis with IPH on MR images would undergo immediate carotid endarterectomy in addition to ongoing intensive medical therapy. Patients in the medical therapy-only group could undergo carotid endarterectomy only with substantial carotid artery stenosis disease progression. Lifetime quality-adjusted life years (QALYs) and costs were modeled for patients with asymptomatic carotid artery stenosis with 70%-89% and 50%-69% carotid artery stenosis at presentation. Risks of stroke and complications from carotid endarterectomy, costs, and quality of life values were estimated from published sources. Results The medical therapy-based strategy had a lower life expectancy (12.65 years vs 12.95 years), lower lifetime QALYs (9.96 years vs 10.05 years), and lower lifetime costs ($13 699 vs $15 297) when compared with the MR imaging IPH-based strategy. The incremental cost-effectiveness ratio (ICER) for the MR imaging IPH strategy compared with the medical therapy-based strategy was $16 000 per QALY by using a base-case 70-year-old patient. When using starting patient ages of 60 and 80 years, the ICERs for the MR imaging IPH strategy were $3100 per QALY and $73 000 per QALY, respectively. The ICERs for the MR imaging IPH strategy were slightly higher at all ages for 50%-69% stenosis but remained below a willingness-to-pay threshold of $100 000 per QALY for starting ages of 60 and 70 years. Conclusion MR imaging IPH can be used as a cost-effective tool to identify patients with asymptomatic carotid artery stenosis most likely to benefit from carotid endarterectomy. (©) RSNA, 2015 Online supplemental material is available for this article. An earlier incorrect version of this article appeared online. This article was corrected on July 14, 2015. PMID:26098459

  7. Image quality scaling of electrophotographic prints

    NASA Astrophysics Data System (ADS)

    Johnson, Garrett M.; Patil, Rohit A.; Montag, Ethan D.; Fairchild, Mark D.

    2003-12-01

    Two psychophysical experiments were performed scaling overall image quality of black-and-white electrophotographic (EP) images. Six different printers were used to generate the images. There were six different scenes included in the experiment, representing photographs, business graphics, and test-targets. The two experiments were split into a paired-comparison experiment examining overall image quality, and a triad experiment judging overall similarity and dissimilarity of the printed images. The paired-comparison experiment was analyzed using Thurstone's Law, to generate an interval scale of quality, and with dual scaling, to determine the independent dimensions used for categorical scaling. The triad experiment was analyzed using multidimensional scaling to generate a psychological stimulus space. The psychophysical results indicated that the image quality was judged mainly along one dimension and that the relationships among the images can be described with a single dimension in most cases. Regression of various physical measurements of the images to the paired comparison results showed that a small number of physical attributes of the images could be correlated with the psychophysical scale of image quality. However, global image difference metrics did not correlate well with image quality.

  8. Cognitive issues in image quality measurement

    NASA Astrophysics Data System (ADS)

    de Ridder, Huib

    2001-01-01

    Designers of imaging systems, image processing algorithms, etc., usually take for granted that methods for assessing perceived image quality produce unbiased estimates of the viewers' quality impression. Quality judgments, however, are affected by the judgment strategies induced by the experimental procedures. In this paper the results of two experiments are presented illustrating the influence judgment strategies can have on quality judgments. The first experiment concerns contextual effects due to the composition of the stimulus sets. Subjects assessed the sharpness of two differently composed sets of blurred versions of one static image. The sharpness judgments for the blurred images present in both stimulus sets were found to be dependent on the composition of the set as well as the scaling technique employed. In the second experiment subjects assessed either the overall quality or the overall impairment of manipulated and standard JPEG-coded images containing two main artifacts. The results indicate a systematic different between the quality and impairment judgments that could be interpreted as instruction-based different weighting of the two artifacts. Again, some influence of scaling techniques was observed. The results of both experiments underscore the important role judgment strategies play in the psychophysical evaluation of image quality. Ignoring this influence on quality judgments may lead to invalid conclusions about the viewers' impression of image quality.

  9. Phase congruency assesses hyperspectral image quality

    NASA Astrophysics Data System (ADS)

    Shao, Xiaopeng; Zhong, Cheng

    2012-10-01

    Blind image quality assessment (QA) is a tough task especially for hyperspectral imagery which is degraded by noise, distortion, defocus, and other complex factors. Subjective hyperspectral imagery QA methods are basically measured the degradation of image from human perceptual visual quality. As the most important image quality measurement features, noise and blur, determined the image quality greatly, are employed to predict the objective hyperspectral imagery quality of each band. We demonstrate a novel no-reference hyperspectral imagery QA model based on phase congruency (PC), which is a dimensionless quantity and provides an absolute measure of the significance of feature point. First, Log Gabor wavelet is used to calculate the phase congruency of frequencies of each band image. The relationship between noise and PC can be derived from above transformation under the assumption that noise is additive. Second, PC focus measure evaluation model is proposed to evaluate blur caused by different amounts of defocus. The ratio and mean factors of edge blur level and noise is defined to assess the quality of each band image. This image QA method obtains excellent correlation with subjective image quality score without any reference. Finally, the PC information is utilized to improve the quality of some bands images.

  10. Development of photoacoustic radar imaging for endoscopy (coronary artery) diagnosis A novel intravascular imager technology of fatty acids in arteries responsible for heart disease and

    E-print Network

    Sun, Yu

    th year thesis will involve testing of photoacoustic and ultrasonic intravascular signal responses developed. The imager consists of a catheter carrying combined photoacoustic and ultrasonic sources for coronary artery disease at an earlier stage than today's purely ultrasonic and purely optical imaging

  11. Image mosaicing: Create High Quality Panoramic Multi-spectral Image

    E-print Network

    Tokyo, University of

    Image mosaicing: Create High Quality Panoramic Multi-spectral Image by Akifumi Ikari A Senior and virtual reality, multi-spectral and panoramic images are needed. To get a panoramic multi-spectral images for restriction of the resolution of a camera, a photography angle, etc, by taking the scene many times so

  12. Signal and image processing for early detection of coronary artery diseases: A review

    NASA Astrophysics Data System (ADS)

    Mobssite, Youness; Samir, B. Belhaouari; Mohamad Hani, Ahmed Fadzil B.

    2012-09-01

    Today biomedical signals and image based detection are a basic step to diagnose heart diseases, in particular, coronary artery diseases. The goal of this work is to provide non-invasive early detection of Coronary Artery Diseases relying on analyzing images and ECG signals as a combined approach to extract features, further classify and quantify the severity of DCAD by using B-splines method. In an aim of creating a prototype of screening biomedical imaging for coronary arteries to help cardiologists to decide the kind of treatment needed to reduce or control the risk of heart attack.

  13. Robust information gain based fuzzy c-means clustering and classification of carotid artery ultrasound images.

    PubMed

    Hassan, Mehdi; Chaudhry, Asmatullah; Khan, Asifullah; Iftikhar, M Aksam

    2014-02-01

    In this paper, a robust method is proposed for segmentation of medical images by exploiting the concept of information gain. Medical images contain inherent noise due to imaging equipment, operating environment and patient movement during image acquisition. A robust medical image segmentation technique is thus inevitable for accurate results in subsequent stages. The clustering technique proposed in this work updates fuzzy membership values and cluster centroids based on information gain computed from the local neighborhood of a pixel. The proposed approach is less sensitive to noise and produces homogeneous clustering. Experiments are performed on medical and non-medical images and results are compared with state of the art segmentation approaches. Analysis of visual and quantitative results verifies that the proposed approach outperforms other techniques both on noisy and noise free images. Furthermore, the proposed technique is used to segment a dataset of 300 real carotid artery ultrasound images. A decision system for plaque detection in the carotid artery is then proposed. Intima media thickness (IMT) is measured from the segmented images produced by the proposed approach. A feature vector based on IMT values is constructed for making decision about the presence of plaque in carotid artery using probabilistic neural network (PNN). The proposed decision system detects plaque in carotid artery images with high accuracy. Finally, effect of the proposed segmentation technique has also been investigated on classification of carotid artery ultrasound images. PMID:24239296

  14. Feasibility of proximal right coronary artery imaging by 2D and 3D echocardiography in comparison to coronary angiography

    PubMed Central

    Lange, Katharina; Pfeiffer, Dietrich; Hagendorff, Andreas

    2015-01-01

    The present study was carried out to test the feasibility of proximal right coronary artery (RCA) imaging and to detect proximal RCA narrowing and occlusion by 2D and 3D transthoracic echocardiography in comparison to coronary angiography (CA). Standardised 2D and 3D echocardiography were performed prior to CA in 97 patients with sinus rhythm. The following parameters were determined: the longest longitudinal detectable RCA segment, the minimum and maximum width of the RCA, the area and number of detectable narrowing >50% of the proximal RCA and the correlation between the echocardiographic and angiographic findings. The visualisation of the proximal RCA and the detection of coronary artery narrowing in the proximal RCA are generally possible. Differences in width and area were not statistically significant between 2D and 3D echocardiography, but showed significant differences between echocardiography and CA. For the detection of proximal RCA narrowing, higher sensitivity and specificity values were obtained by 2D than by 3D echocardiography. However, in patients with sufficient image quality 3D echocardiography permits a more detailed visualisation of the anatomical proportions and an en-face view into the RCA ostium. The visualisation of the proximal RCA is feasible and narrowing can be detected by 2D and 3D echocardiography if image quality is sufficient. CA is the gold standard for the detection of coronary artery stenoses. However, the potential of this new approach is clinically important because crucial findings of the proximal RCA can be presumably detected non-invasively prior to CA.

  15. Computer-generated 3D ultrasound images of the carotid artery

    NASA Technical Reports Server (NTRS)

    Selzer, Robert H.; Lee, Paul L.; Lai, June Y.; Frieden, Howard J.; Blankenhorn, David H.

    1989-01-01

    A method is under development to measure carotid artery lesions from a computer-generated three-dimensional ultrasound image. For each image, the position of the transducer in six coordinates (x, y, z, azimuth, elevation, and roll) is recorded and used to position each B-mode picture element in its proper spatial position in a three-dimensional memory array. After all B-mode images have been assembled in the memory, the three-dimensional image is filtered and resampled to produce a new series of parallel-plane two-dimensional images from which arterial boundaries are determined using edge tracking methods.

  16. Automated anatomical labeling method for abdominal arteries extracted from 3D abdominal CT images

    NASA Astrophysics Data System (ADS)

    Oda, Masahiro; Hoang, Bui Huy; Kitasaka, Takayuki; Misawa, Kazunari; Fujiwara, Michitaka; Mori, Kensaku

    2012-02-01

    This paper presents an automated anatomical labeling method of abdominal arteries. In abdominal surgery, understanding of blood vessel structure concerning with a target organ is very important. Branching pattern of blood vessels differs among individuals. It is required to develop a system that can assist understanding of a blood vessel structure and anatomical names of blood vessels of a patient. Previous anatomical labbeling methods for abdominal arteries deal with either of the upper or lower abdominal arteries. In this paper, we present an automated anatomical labeling method of both of the upper and lower abdominal arteries extracted from CT images. We obtain a tree structure of artery regions and calculate feature values for each branch. These feature values include the diameter, curvature, direction, and running vectors of a branch. Target arteries of this method are grouped based on branching conditions. The following processes are separately applied for each group. We compute candidate artery names by using classifiers that are trained to output artery names. A correction process of the candidate anatomical names based on the rule of majority is applied to determine final names. We applied the proposed method to 23 cases of 3D abdominal CT images. Experimental results showed that the proposed method is able to perform nomenclature of entire major abdominal arteries. The recall and the precision rates of labeling are 79.01% and 80.41%, respectively.

  17. How much image noise can be added in cardiac x-ray imaging without loss in perceived image quality?

    NASA Astrophysics Data System (ADS)

    Gislason-Lee, Amber J.; Kumcu, Asli; Kengyelics, Stephen M.; Brettle, David S.; Treadgold, Laura A.; Sivananthan, Mohan; Davies, Andrew G.

    2015-10-01

    Cardiologists use x-ray image sequences of the moving heart acquired in real-time to diagnose and treat cardiac patients. The amount of radiation used is proportional to image quality; however, exposure to radiation is damaging to patients and personnel. The amount by which radiation dose can be reduced without compromising patient care was determined. For five patient image sequences, increments of computer-generated quantum noise (white + colored) were added to the images, frame by frame using pixel-to-pixel addition, to simulate corresponding increments of dose reduction. The noise adding software was calibrated for settings used in cardiac procedures, and validated using standard objective and subjective image quality measurements. The degraded images were viewed next to corresponding original (not degraded) images in a two-alternative-forced-choice staircase psychophysics experiment. Seven cardiologists and five radiographers selected their preferred image based on visualization of the coronary arteries. The point of subjective equality, i.e., level of degradation where the observer could not perceive a difference between the original and degraded images, was calculated; for all patients the median was 33%±15% dose reduction. This demonstrates that a 33%±15% increase in image noise is feasible without being perceived, indicating potential for 33%±15% dose reduction without compromising patient care.

  18. 3DVIEWNIX-AVS: a software package for separate visualization of arteries and veins in CE-MRA images

    NASA Astrophysics Data System (ADS)

    Lei, Tianhu; Udupa, Jayaram K.; Odhner, Dewey; Saha, Punam K.

    2001-05-01

    Our earlier study developed a computerized method, based on fuzzy connected object delineation principles and algorithms, for artery and vein separation in CE-MRA images. This paper reports its current development - a software package - for the routine clinical use. The software package, termed 3DVIEWNIX-AVS, consists of the following major operational parts: 1)converting data from DICOM3 to 3DVIEWNIX format, 2) previewing slices/creating VOI and MIP shell, 3) segmenting vessel, 4) separating artery and vein, 5) shell rendering vascular structures and creating animations. This package has been applied to EPIX Medical Inc's CE-MRA data (AngioMark MS-325). 133 original CE-MRA data sets (of 52 patients) from 6 hospitals have been processed. In all case studies, unified parameter settings produce correct artery/vein separation. The current package is running on a Pentium PC under Linux and the total operation time per study is about 10 minutes. The strengths of this software package are its 1) minimal user interaction, 2) minimal anatomic knowledge requirements on human vascular system, 3) clinically required speed, 4) free entry to any operational stages, 5) reproducible, reliable, high quality of results, and 6) cost effective computer implementation. To date, it seems to be the only software package (using an image processing approach) available for artery and vein separation for the routine use in a clinical setting.

  19. Unusual Malignant Coronary Artery Anomaly: Results of Coronary Angiography, MR Imaging, and Multislice CT

    SciTech Connect

    Apitzsch, Jonas; Kuehl, Harald P.; Muehlenbruch, Georg; Mahnken, Andreas H.

    2010-04-15

    We report the case of a man with an uncommon anomaly of the origin and course of the left coronary artery. Clinical, coronary angiography, magnetic resonance imaging, and multislice computed tomography findings of this intermittently symptomatic 49 year-old patient with the rare anomaly of his left coronary artery stemming from the right sinus of Valsalva and taking an interarterial and intraseptal course are presented. The diagnostic value of the different imaging modalities is discussed.

  20. Automatic quality assessment of planetary images

    NASA Astrophysics Data System (ADS)

    Sidiropoulos, P.; Muller, J.-P.

    2015-10-01

    A significant fraction of planetary images are corrupted beyond the point that much scientific meaning can be extracted. For example, transmission errors result in missing data which is unrecoverable. The available planetary image datasets include many such "bad data", which both occupy valuable scientific storage resources and create false impressions about planetary image availability for specific planetary objects or target areas. In this work, we demonstrate a pipeline that we have developed to automatically assess the quality of planetary images. Additionally, this method discriminates between different types of image degradation, such as low-quality originating from camera flaws or low-quality triggered by atmospheric conditions, etc. Examples of quality assessment results for Viking Orbiter imagery will be also presented.

  1. Digital Image Processing Of Arterial Thrombi Images, Recorded By Light Transmission

    NASA Astrophysics Data System (ADS)

    Nyssen, Marc; Blockeel, Erik; Bourgain, Rene

    1986-05-01

    For several years, the formation and evolution of thrombi in small arteries of rats has been quantitatively studied at the Laboratory of Physiology and Physiopathology at the V.U.B. Global size parameters can be determined by projecting the image of a small arterial segment onto photosensitive cells. The transmitted light intensity is a measure for the thrombotic phenomenon. This unique method permitted extensive in vivo study of the platelet-vessel wall interaction and local thrombosis. Now, a further development has emerged with the aim to improve the resolution of these measurements in order to get information on texture and form of the thrombotic mass at any stage of its evolution. Therefore a thorough understanding of how light propagates through non hemolized blood was essential. For this purpose, the Medical Informatics department developed a system to record and process digital images of the thrombotic phenomenon. For the processing and attempt to reconstruct the thrombi, a model describing the light transmission in a dispersive medium such as flowing blood had to be worked out. Application of results from Twersky's multiple scattering theory, combined with appropriate border conditions and parameter values was attempted. In the particular situation we studied, the dispersive properties of the flowing blood were found to be highly anisotropic. An explanation for this phenomenon could be given by considering the alignment of red blood cells in the blood flow. In order to explain the measured intensity profiles, we had to postulate alignment in the plane perpendicular to the flow as well. The theoretical predictions are in good agreement with the experimental values if we assume almost perfect alignment of the erythrocytes such that their short axes are pointing in the direction of the center of the artery. Conclusive evidence of the interaction between local flow properties and light transmission could be found by observing arteries with perturbated flow.

  2. Imaging Food Quality Flemming Mller

    E-print Network

    fermented sausages. The imaging techniques ranged from single wavelength images, multispectral to hyperspectral images. The effect of different light geometries were utilised in measuring the light reflection.eks. temperatur, NIR og masse spektrofotometri. Billeder og særligt spektralbilleder indeholder store mængder data

  3. Cerebral Arterial Calcification Is an Imaging Prognostic Marker for Revascularization Treatment of Acute Middle Cerebral Arterial Occlusion

    PubMed Central

    Lee, Seong-Joon; Hong, Ji Man; Lee, Manyong; Huh, Kyoon; Choi, Jin Wook

    2015-01-01

    Background and Purpose To study the significance of intracranial artery calcification as a prognostic marker for acute ischemic stroke patients undergoing revascularization treatment after middle cerebral artery (MCA) trunk occlusion. Methods Patients with acute MCA trunk occlusion, who underwent intravenous and/or intra-arterial revascularization treatment, were enrolled. Intracranial artery calcification scores were calculated by counting calcified intracranial arteries among major seven arteries on computed tomographic angiography. Patients were divided into high (HCB; score ?3) or low calcification burden (LCB; score <3) groups. Demographic, imaging, and outcome data were compared, and whether HCB is a prognostic factor was evaluated. Grave prognosis was defined as modified Rankin Scale 5-6 for this study. Results Of 80 enrolled patients, the HCB group comprised 15 patients, who were older, and more commonly had diabetes than patients in the LCB group. Initial National Institutes of Health Stroke Scale (NIHSS) scores did not differ (HCB 13.3±2.7 vs. LCB 14.6±3.8) between groups. The final good reperfusion after revascularization treatment (thrombolysis in cerebral infarction score 2b-3, HCB 66.7% vs. LCB 69.2%) was similarly achieved in both groups. However, the HCB group had significantly higher NIHSS scores at discharge (16.0±12.3 vs. 7.9±8.3), and more frequent grave outcome at 3 months (57.1% vs. 22.0%) than the LCB group. HCB was proven as an independent predictor for grave outcome at 3 months when several confounding factors were adjusted (odds ratio 4.135, 95% confidence interval, 1.045-16.359, P=0.043). Conclusions Intracranial HCB was associated with grave prognosis in patients who have undergone revascularization for acute MCA trunk occlusion. PMID:25692109

  4. Multiresolution Approach for Noncontact Measurements of Arterial Pulse Using Thermal Imaging

    NASA Astrophysics Data System (ADS)

    Chekmenev, Sergey Y.; Farag, Aly A.; Miller, William M.; Essock, Edward A.; Bhatnagar, Aruni

    This chapter presents a novel computer vision methodology for noncontact and nonintrusive measurements of arterial pulse. This is the only investigation that links the knowledge of human physiology and anatomy, advances in thermal infrared (IR) imaging and computer vision to produce noncontact and nonintrusive measurements of the arterial pulse in both time and frequency domains. The proposed approach has a physical and physiological basis and as such is of a fundamental nature. A thermal IR camera was used to capture the heat pattern from superficial arteries, and a blood vessel model was proposed to describe the pulsatile nature of the blood flow. A multiresolution wavelet-based signal analysis approach was applied to extract the arterial pulse waveform, which lends itself to various physiological measurements. We validated our results using a traditional contact vital signs monitor as a ground truth. Eight people of different age, race and gender have been tested in our study consistent with Health Insurance Portability and Accountability Act (HIPAA) regulations and internal review board approval. The resultant arterial pulse waveforms exactly matched the ground truth oximetry readings. The essence of our approach is the automatic detection of region of measurement (ROM) of the arterial pulse, from which the arterial pulse waveform is extracted. To the best of our knowledge, the correspondence between noncontact thermal IR imaging-based measurements of the arterial pulse in the time domain and traditional contact approaches has never been reported in the literature.

  5. Automated measurement of pulmonary artery in low-dose non-contrast chest CT images

    NASA Astrophysics Data System (ADS)

    Xie, Yiting; Liang, Mingzhu; Yankelevitz, David F.; Henschke, Claudia I.; Reeves, Anthony P.

    2015-03-01

    A new measurement of the pulmonary artery diameter is obtained where the artery may be robustly segmented between the heart and the artery bifurcation. An automated algorithm is presented that can make this pulmonary artery measurement in low-dose non-contrast chest CT images. The algorithm uses a cylinder matching method following geometric constraints obtained from other adjacent organs that have been previously segmented. This new measurement and the related ratio of pulmonary artery to aortic artery measurement are compared to traditional manual approaches for pulmonary artery characterization. The algorithm was qualitatively evaluated on 124 low-dose and 223 standard-dose non-contrast chest CT scans from two public datasets; 324 out of the 347 cases had good segmentations and in the other 23 cases there was significant boundary inaccuracy. For quantitative evaluation, the comparison was to manually marked pulmonary artery boundary in an axial slice in 45 cases; the resulting average Dice Similarity Coefficient was 0.88 (max 0.95, min 0.74). For the 45 cases with manual markings, the correlation between the automated pulmonary artery to ascending aorta diameter ratio and manual ratio at pulmonary artery bifurcation level was 0.81. Using Bland-Altman analysis, the mean difference of the two ratios was 0.03 and the limits of agreement was (-0.12, 0.18). This automated measurement may have utility as an alternative to the conventional manual measurement of pulmonary artery diameter at the bifurcation level especially in the context of noisy low-dose CT images.

  6. Review of duplex and colour Doppler imaging of lower-limb arteries and veins.

    PubMed

    Lunt, M J

    1999-04-01

    Ultrasonic imaging provides a non-invasive assessment of the arterial and venous circulation in the lower limb and is accepted as a valuable diagnostic technique. Grey-scale images identify plaque and thrombus, duplex assessment provides a measurement of blood velocity through a vessel, and colour Doppler imaging enables the rapid localization of arterial stenoses and occlusions and the identification of incompetent veins. This article outlines the principles of the different techniques and presents normal images. Procedures for investigating arterial stenoses, superficial venous incompetence and deep venous thrombosis are described, abnormal images presented and the limitations discussed. It is hoped to provide an insight into the strengths and limitations of ultrasonic vascular investigations for those involved in tissue viability and ulcer management. PMID:10480971

  7. Low-quality image enhancement using

    E-print Network

    Schettini, Raimondo

    , and Raimondo Schettini Università degli Studi di Milano-Bicocca, DISCo, Via Bicocca degli Arcimboldi 8, 20126 Milano, Italy E-mail: gasparini@disco.unimib.it Abstract. Low quality images are often corrupted by arti

  8. The effect of adaptive iterative dose reduction on image quality in 320-detector row CT coronary angiography

    PubMed Central

    Tatsugami, F; Matsuki, M; Nakai, G; Inada, Y; Kanazawa, S; Takeda, Y; Morita, H; Takada, H; Yoshikawa, S; Fukumura, K; Narumi, Y

    2012-01-01

    Objective To evaluate the effect of adaptive iterative dose reduction (AIDR) on image noise and image quality as compared with standard filtered back projection (FBP) in 320-detector row CT coronary angiography (CTCA). Methods 50 patients (14 females, mean age 68±9 years) who underwent CTCA (100 kV or 120 kV, 400–580 mA) within a single heartbeat were enrolled. Studies were reconstructed with FBP and subsequently AIDR. Image noise, vessel contrast and contrast-to-noise ratio (CNR) in the coronary arteries were evaluated. Overall image quality for coronary arteries was assessed using a five-point scale (1, non-diagnostic; 5, excellent). Results All the examinations were performed in a single heartbeat. Image noise in the aorta was significantly lower in data sets reconstructed with AIDR than in those reconstructed with FBP (21.4±3.1 HU vs 36.9±4.5 HU; p<0.001). No significant differences were observed between FBP and AIDR for the mean vessel contrast (HU) in the proximal coronary arteries. Consequently, CNRs in the proximal coronary arteries were higher in the AIDR group than in the FBP group (p<0.001). The mean image quality score was improved by AIDR (3.75±0.38 vs 4.24±0.38; p<0.001). Conclusion The use of AIDR reduces image noise and improves image quality in 320-detector row CTCA. PMID:22253355

  9. Joint segmentation of lumen and outer wall from femoral artery MR images: Towards 3D imaging measurements of peripheral arterial disease.

    PubMed

    Ukwatta, Eranga; Yuan, Jing; Qiu, Wu; Rajchl, Martin; Chiu, Bernard; Fenster, Aaron

    2015-12-01

    Three-dimensional (3D) measurements of peripheral arterial disease (PAD) plaque burden extracted from fast black-blood magnetic resonance (MR) images have shown to be more predictive of clinical outcomes than PAD stenosis measurements. To this end, accurate segmentation of the femoral artery lumen and outer wall is required for generating volumetric measurements of PAD plaque burden. Here, we propose a semi-automated algorithm to jointly segment the femoral artery lumen and outer wall surfaces from 3D black-blood MR images, which are reoriented and reconstructed along the medial axis of the femoral artery to obtain improved spatial coherence between slices of the long, thin femoral artery and to reduce computation time. The developed segmentation algorithm enforces two priors in a global optimization manner: the spatial consistency between the adjacent 2D slices and the anatomical region order between the femoral artery lumen and outer wall surfaces. The formulated combinatorial optimization problem for segmentation is solved globally and exactly by means of convex relaxation using a coupled continuous max-flow (CCMF) model, which is a dual formulation to the convex relaxed optimization problem. In addition, the CCMF model directly derives an efficient duality-based algorithm based on the modern multiplier augmented optimization scheme, which has been implemented on a GPU for fast computation. The computed segmentations from the developed algorithm were compared to manual delineations from experts using 20 black-blood MR images. The developed algorithm yielded both high accuracy (Dice similarity coefficients ?87% for both the lumen and outer wall surfaces) and high reproducibility (intra-class correlation coefficient of 0.95 for generating vessel wall area), while outperforming the state-of-the-art method in terms of computational time by a factor of ?20. PMID:26387053

  10. No training blind image quality assessment

    NASA Astrophysics Data System (ADS)

    Chu, Ying; Mou, Xuanqin; Ji, Zhen

    2014-03-01

    State of the art blind image quality assessment (IQA) methods generally extract perceptual features from the training images, and send them into support vector machine (SVM) to learn the regression model, which could be used to further predict the quality scores of the testing images. However, these methods need complicated training and learning, and the evaluation results are sensitive to image contents and learning strategies. In this paper, two novel blind IQA metrics without training and learning are firstly proposed. The new methods extract perceptual features, i.e., the shape consistency of conditional histograms, from the joint histograms of neighboring divisive normalization transform coefficients of distorted images, and then compare the length attribute of the extracted features with that of the reference images and degraded images in the LIVE database. For the first method, a cluster center is found in the feature attribute space of the natural reference images, and the distance between the feature attribute of the distorted image and the cluster center is adopted as the quality label. The second method utilizes the feature attributes and subjective scores of all the images in the LIVE database to construct a dictionary, and the final quality score is calculated by interpolating the subjective scores of nearby words in the dictionary. Unlike the traditional SVM based blind IQA methods, the proposed metrics have explicit expressions, which reflect the relationships of the perceptual features and the image quality well. Experiment results in the publicly available databases such as LIVE, CSIQ and TID2008 had shown the effectiveness of the proposed methods, and the performances are fairly acceptable.

  11. Noninvasive ergonovine maleate provocative testing for coronary artery spasm: the need for routine thallium-201 imaging

    SciTech Connect

    Shanes, J.G.; Krone, R.J.; Fisher, K.; Shah, B.; Eisenkramer, G.; Humphrey, J.R.

    1983-01-01

    We administered ergonovine and used both electrocardiographic monitoring and thallium-/sup 201/ (/sup 201/Tl) imaging to detect reversible ischemia in 100 patients. Patients already established as having coronary artery spasm and those with nonbypassed, proximal, high-grade coronary artery stenosis were excluded. No complication occurred in any patient. The use of thallium imaging in addition to electrocardiographic monitoring resulted in a higher degree of sensitivity than did ECG monitoring alone. Fourteen patients demonstrated evidence of coronary artery spasm as documented by /sup 201/Tl imaging but of the 14, significant ECG changes occurred in only 50%, and classic ST segment elevation in 21%. Thus, in carefully selected patients the noninvasive provocation of coronary spasm can be accomplished safely, but ECG monitoring must be combined with thallium-/sup 201/ imaging to achieve an acceptable degree of sensitivity.

  12. Development of functional in vivo imaging of cerebral lenticulostriate artery using novel synchrotron radiation angiography

    NASA Astrophysics Data System (ADS)

    Lin, Xiaojie; Miao, Peng; Mu, Zhihao; Jiang, Zhen; Lu, Yifan; Guan, Yongjing; Chen, Xiaoyan; Xiao, Tiqiao; Wang, Yongting; Yang, Guo-Yuan

    2015-02-01

    The lenticulostriate artery plays a vital role in the onset and development of cerebral ischemia. However, current imaging techniques cannot assess the in vivo functioning of small arteries such as the lenticulostriate artery in the brain of rats. Here, we report a novel method to achieve a high resolution multi-functional imaging of the cerebrovascular system using synchrotron radiation angiography, which is based on spatio-temporal analysis of contrast density in the arterial cross section. This method provides a unique tool for studying the sub-cortical vascular elasticity after cerebral ischemia in rats. Using this technique, we demonstrated that the vascular elasticity of the lenticulostriate artery decreased from day 1 to day 7 after transient middle cerebral artery occlusion in rats and recovered from day 7 to day 28 compared to the controls (p < 0.001), which paralleled with brain edema formation and inversely correlated with blood flow velocity (p < 0.05). Our results demonstrated that the change of vascular elasticity was related to the levels of brain edema and the velocity of focal blood flow, suggesting that reducing brain edema is important for the improvement of the function of the lenticulostriate artery in the ischemic brain.

  13. Perceptual image quality and telescope performance ranking

    NASA Astrophysics Data System (ADS)

    Lentz, Joshua K.; Harvey, James E.; Marshall, Kenneth H.; Salg, Joseph; Houston, Joseph B.

    2010-08-01

    Launch Vehicle Imaging Telescopes (LVIT) are expensive, high quality devices intended for improving the safety of vehicle personnel, ground support, civilians, and physical assets during launch activities. If allowed to degrade from the combination of wear, environmental factors, and ineffective or inadequate maintenance, these devices lose their ability to provide adequate quality imagery to analysts to prevent catastrophic events such as the NASA Space Shuttle, Challenger, accident in 1986 and the Columbia disaster of 2003. A software tool incorporating aberrations and diffraction that was developed for maintenance evaluation and modeling of telescope imagery is presented. This tool provides MTF-based image quality metric outputs which are correlated to ascent imagery analysts' perception of image quality, allowing a prediction of usefulness of imagery which would be produced by a telescope under different simulated conditions.

  14. Imaging of blunt arterial trauma of the upper extremity in children.

    PubMed

    Hodina, M; Gudinchet, F; Reinberg, O; Schnyder, P

    2001-08-01

    We report four patients with blunt arterial trauma of the upper limb following unusual mechanisms of injury in two patients (one fell on the handlebars of his bicycle, the second was crushed by a moving lawn mower) and due to bicycle accidents in two further patients. The use of digital subtraction angiography (DSA) in all patients, together with colour Doppler imaging (CDI) in one patient, provided optimum preoperative identification and localisation of the arterial lesions. PMID:11550768

  15. Requirements for imaging vulnerable plaque in the coronary artery using a coded aperture imaging system

    NASA Astrophysics Data System (ADS)

    Tozian, Cynthia

    A coded aperture1 plate was employed on a conventional gamma camera for 3D single photon emission computed tomography (SPECT) imaging on small animal models. The coded aperture design was selected to improve the spatial resolution and decrease the minimum detectable activity (MDA) required to image plaque formation in the APoE (apolipoprotein E) gene deficient mouse model when compared to conventional SPECT techniques. The pattern that was tested was a no-two-holes-touching (NTHT) modified uniformly redundant array (MURA) having 1,920 pinholes. The number of pinholes combined with the thin sintered tungsten plate was designed to increase the efficiency of the imaging modality over conventional gamma camera imaging methods while improving spatial resolution and reducing noise in the image reconstruction. The MDA required to image the vulnerable plaque in a human cardiac-torso mathematical phantom was simulated with a Monte Carlo code and evaluated to determine the optimum plate thickness by a receiver operating characteristic (ROC) yielding the lowest possible MDA and highest area under the curve (AUC). A partial 3D expectation maximization (EM) reconstruction was developed to improve signal-to-noise ratio (SNR), dynamic range, and spatial resolution over the linear correlation method of reconstruction. This improvement was evaluated by imaging a mini hot rod phantom, simulating the dynamic range, and by performing a bone scan of the C-57 control mouse. Results of the experimental and simulated data as well as other plate designs were analyzed for use as a small animal and potentially human cardiac imaging modality for a radiopharmaceutical developed at Bristol-Myers Squibb Medical Imaging Company, North Billerica, MA, for diagnosing vulnerable plaques. If left untreated, these plaques may rupture causing sudden, unexpected coronary occlusion and death. The results of this research indicated that imaging and reconstructing with this new partial 3D algorithm improved the SNR, spatial resolution, dynamic range of 4:1 to 6:1, and decreased the MDA required at the site of a plaque by twofold in comparison with other nuclear medicine imaging methods. Recommendations to increase the field of view (FOV) along with a better imaging geometry would enable placement of larger objects (human heart included) within the fully encoded FOV while improving spatial resolution, magnification factors, and efficiency. Further improvements to the algorithm and imaging system may enable novel vulnerable plaque imaging and early detection of coronary artery disease. 1See definitions beginning on page xvii.

  16. Computerized measurement of mammographic display image quality

    NASA Astrophysics Data System (ADS)

    Chakraborty, Dev P.; Sivarudrappa, Mahesh; Roehrig, Hans

    1999-05-01

    Since the video monitor is widely believed to be the weak link in the imaging chain, it is critical, to include it in the total image quality evaluation. Yet, most physical measurements of mammographic image quality are presently limited to making measurements on the digital matrix, not the displayed image. A method is described to quantitatively measure image quality of mammographic monitors using ACR phantom-based test patterns. The image of the test pattern is digitized using a charge coupled device (CCD) camera, and the resulting image file is analyzed by an existing phantom analysis method (Computer Analysis of Mammography Phantom Images, CAMPI). The new method is called CCD-CAMPI and it yields the Signal-to-Noise-Ratio (SNR) for an arbitrary target shape (e.g., speck, mass or fiber). In this work we show the feasibility of this idea for speck targets. Also performed were physical image quality characterization of the monitor (so-called Fourier measures) and analysis by another template matching method due to Tapiovaara and Wagner (TW) which is closely related to CAMPI. The methods were applied to a MegaScan monitor. Test patterns containing a complete speck group superposed on a noiseless background were displayed on the monitor and a series of CCD images were acquired. These images were subjected to CCD-CAMPI and TW analyses. It was found that the SNR values for the CCD-CAMPI method tracked those of the TW method, although the latter measurements were considerably less precise. The TW SNR measure was also about 25% larger than the CCD-CAMPI determination. These differences could be understood from the manner in which the two methods evaluate the noise. Overall accuracy of the CAMPI SNR determination was 4.1% for single images when expressed as a coefficient of variance. While the SNR measures are predictable from the Fourier measures the number of images and effort required is prohibitive and it is not suited to Quality Control (QC). Unlike the Fourier measures and the TW method, CCD-CAMPI is capable of yielding speck SNR on a single image. This is based on preliminary work and more complete testing is underway. Based on the early promising results, we expect that the CCD-CAMI method can be adapted to routine image QC of monitors using inexpensive equipment.

  17. Images in Clinical Medicine. Left Main Coronary Artery Stent Migration.

    PubMed

    Adigopula, Sasikanth; Nsair, Ali

    2015-11-12

    A 22-year-old woman with primary pulmonary hypertension presented with displacement of stents that had been implanted in the left main coronary artery and had migrated into the aorta. She had been referred to our center for evaluation for lung transplantation. PMID:26559574

  18. Automating Image Enhancement Optimization Using Image Quality Metrics

    NASA Astrophysics Data System (ADS)

    Gerwe, D.; Luna, C.; Calef, B.

    2014-09-01

    Image enhancement algorithms typically require tuning one or more input parameters to get the best results. Skipping this step or poor choice of values can often result in significant decrease in enhancement level or even degrade the image. This paper demonstrates the utility of image quality metrics in automating this tuning process for Space Situational Awareness imagery of resolved Resident Space Objects. The metrics considered in this study compare an original pristine image to the final displayed image, thus only apply directly to simulated images. However it is shown that a training set can be used to determine the best settings as a function of measureable imaging condition (light level, r0, …) to produce a look-up table that can be used for field collected data.

  19. Complimentary use of epicardial echo imaging and Doppler in quantification of coronary artery stenoses

    NASA Astrophysics Data System (ADS)

    Richards, Kent L.; Cannon, Scott R.

    1990-08-01

    As more advanced therapeutic procedures are performed on coronary arteries during open chest surgery more advanced diagnostic procedures will be required to define the location and severity of coronary artery disease. This manuscript describes our preliminary experiences in identifying human coronary artery stenoses using epicardial two-dimensional color flow Doppler. Once the lesions were identified we used standard echo Doppler and imaging techniques to define their severity. The accuracy of stenotic cross sectional area calculated using the continuity equation and pressure gradient calculated using the Bernoulli equation were defined using a pulsatile flow model of the coronary circulation. Suggestions about further hardware development required to allow easy clinical application of this technique are described. 1 - CLINICAL NEED FOR INTRA-OPERATIVE EVAUJATION OFCORONARY ARTERIES The severity of coronary artery disease in adults who require coronary bypass surgery has changed significantly in the last ten years. More effective medications used to control angina pectoris and the wide use of percutaneous y artery angioplasty have delayed the timing of surgery until atherosclerotic involvement is more extensive. In addition patients who have had initial coronary bypass operations are now reaching ages at which atherosclerotic involvement of their bypass grafts and native vessels has progressed and reoperation is required. To meet the challenge of coronary arteries with multiple lesions or diffuse disease intraoperative angioplasty devices are being developed. Whether bypass surgery for advanced lesions or reoperation of

  20. Perceptual Quality Assessment of Screen Content Images.

    PubMed

    Yang, Huan; Fang, Yuming; Lin, Weisi

    2015-11-01

    Research on screen content images (SCIs) becomes important as they are increasingly used in multi-device communication applications. In this paper, we present a study on perceptual quality assessment of distorted SCIs subjectively and objectively. We construct a large-scale screen image quality assessment database (SIQAD) consisting of 20 source and 980 distorted SCIs. In order to get the subjective quality scores and investigate, which part (text or picture) contributes more to the overall visual quality, the single stimulus methodology with 11 point numerical scale is employed to obtain three kinds of subjective scores corresponding to the entire, textual, and pictorial regions, respectively. According to the analysis of subjective data, we propose a weighting strategy to account for the correlation among these three kinds of subjective scores. Furthermore, we design an objective metric to measure the visual quality of distorted SCIs by considering the visual difference of textual and pictorial regions. The experimental results demonstrate that the proposed SCI perceptual quality assessment scheme, consisting of the objective metric and the weighting strategy, can achieve better performance than 11 state-of-the-art IQA methods. To the best of our knowledge, the SIQAD is the first large-scale database published for quality evaluation of SCIs, and this research is the first attempt to explore the perceptual quality assessment of distorted SCIs. PMID:26259078

  1. Lessions learned in WISE image quality

    NASA Astrophysics Data System (ADS)

    Kendall, Martha; Duval, Valerie G.; Larsen, Mark F.; Heinrichsen, Ingolf H.; Esplin, Roy W.; Shannon, Mark; Wright, Edward L.

    2010-08-01

    The Wide-Field Infrared Survey Explorer (WISE) mission launched in December of 2009 is a true success story. The mission is performing beyond expectations on-orbit and maintained cost and schedule throughout. How does such a thing happen? A team constantly focused on mission success is a key factor. Mission success is more than a program meeting its ultimate science goals; it is also meeting schedule and cost goals to avoid cancellation. The WISE program can attribute some of its success in achieving the image quality needed to meet science goals to lessons learned along the way. A requirement was missed in early decomposition, the absence of which would have adversely affected end-to-end system image quality. Fortunately, the ability of the cross-organizational team to focus on fixing the problem without pointing fingers or waiting for paperwork was crucial in achieving a timely solution. Asking layman questions early in the program could have revealed requirement flowdown misunderstandings between spacecraft control stability and image processing needs. Such is the lesson learned with the WISE spacecraft Attitude Determination & Control Subsystem (ADCS) jitter control and the image data reductions needs. Spacecraft motion can affect image quality in numerous ways. Something as seemingly benign as different terminology being used by teammates in separate groups working on data reduction, spacecraft ADCS, the instrument, mission operations, and the science proved to be a risk to system image quality. While the spacecraft was meeting the allocated jitter requirement , the drift rate variation need was not being met. This missing need was noticed about a year before launch and with a dedicated team effort, an adjustment was made to the spacecraft ADCS control. WISE is meeting all image quality requirements on-orbit thanks to a diligent team noticing something was missing before it was too late and applying their best effort to find a solution.

  2. Evaluation of diseased coronary arterial branches by polar representations of thallium-201 rotational myocardial imaging

    SciTech Connect

    Iino, T.; Toyosaki, N.; Katsuki, T.; Noda, T.; Natsume, T.; Yaginuma, T.; Hosoda, S.; Furuse, M.

    1987-09-01

    The perfusion territories in polar representations of stress Tl-201 rotational myocardial imaging in patients with angina pectoris who had one diseased coronary segment were analyzed. The lesions proximal or distal to the first major septal perforator in left anterior descending arteries were detected by the presence or absence of defects at the base of the anterior septum. Right coronary artery lesions were detected by the presence of defects at the basal posterior septum, in contrast to the preservation of myocardial uptake at this portion in lesions of the left circumflex artery. The specific defect patterns were detected in cases with lesions at the first diagonal, obtuse marginal, and posterolateral branches. Recognition of these defects in the polar maps allows detailed detection of diseased coronary arterial branches.

  3. Molecular imaging of plaques in coronary arteries with PET and SPECT

    PubMed Central

    Sun, Zhong-Hua; Rashmizal, Hairil; Xu, Lei

    2014-01-01

    Coronary artery disease remains a major cause of mortality. Presence of atherosclerotic plaques in the coronary artery is responsible for lumen stenosis which is often used as an indicator for determining the severity of coronary artery disease. However, the degree of coronary lumen stenosis is not often related to compromising myocardial blood flow, as most of the cardiac events that are caused by atherosclerotic plaques are the result of vulnerable plaques which are prone to rupture. Thus, identification of vulnerable plaques in coronary arteries has become increasingly important to assist identify patients with high cardiovascular risks. Molecular imaging with use of positron emission tomography (PET) and single photon emission computed tomography (SPECT) has fulfilled this goal by providing functional information about plaque activity which enables accurate assessment of plaque stability. This review article provides an overview of diagnostic applications of molecular imaging techniques in the detection of plaques in coronary arteries with PET and SPECT. New radiopharmaceuticals used in the molecular imaging of coronary plaques and diagnostic applications of integrated PET/CT and PET/MRI in coronary plaques are also discussed. PMID:25278976

  4. Radiological Management of Hemoptysis: A Comprehensive Review of Diagnostic Imaging and Bronchial Arterial Embolization

    SciTech Connect

    Chun, Joo-Young Morgan, Robert; Belli, Anna-Maria

    2010-04-15

    Hemoptysis can be a life-threatening respiratory emergency and indicates potentially serious underlying intrathoracic disease. Large-volume hemoptysis carries significant mortality and warrants urgent investigation and intervention. Initial assessment by chest radiography, bronchoscopy, and computed tomography (CT) is useful in localizing the bleeding site and identifying the underlying cause. Multidetector CT angiography is a relatively new imaging technique that allows delineation of abnormal bronchial and nonbronchial arteries using reformatted images in multiple projections, which can be used to guide therapeutic arterial embolization procedures. Bronchial artery embolization (BAE) is now considered to be the most effective procedure for the management of massive and recurrent hemoptysis, either as a first-line therapy or as an adjunct to elective surgery. It is a safe technique in the hands of an experienced operator with knowledge of bronchial artery anatomy and the potential pitfalls of the procedure. Recurrent bleeding is not uncommon, especially if there is progression of the underlying disease process. Prompt repeat embolization is advised in patients with recurrent hemoptysis in order to identify nonbronchial systemic and pulmonary arterial sources of bleeding. This article reviews the pathophysiology and causes of hemoptysis, diagnostic imaging and therapeutic options, and technique and outcomes of BAE.

  5. Imaging of Small Animal Peripheral Artery Disease Models: Recent Advancements and Translational Potential

    PubMed Central

    Lin, Jenny B.; Phillips, Evan H.; Riggins, Ti’Air E.; Sangha, Gurneet S.; Chakraborty, Sreyashi; Lee, Janice Y.; Lycke, Roy J.; Hernandez, Clarissa L.; Soepriatna, Arvin H.; Thorne, Bradford R. H.; Yrineo, Alexa A.; Goergen, Craig J.

    2015-01-01

    Peripheral artery disease (PAD) is a broad disorder encompassing multiple forms of arterial disease outside of the heart. As such, PAD development is a multifactorial process with a variety of manifestations. For example, aneurysms are pathological expansions of an artery that can lead to rupture, while ischemic atherosclerosis reduces blood flow, increasing the risk of claudication, poor wound healing, limb amputation, and stroke. Current PAD treatment is often ineffective or associated with serious risks, largely because these disorders are commonly undiagnosed or misdiagnosed. Active areas of research are focused on detecting and characterizing deleterious arterial changes at early stages using non-invasive imaging strategies, such as ultrasound, as well as emerging technologies like photoacoustic imaging. Earlier disease detection and characterization could improve interventional strategies, leading to better prognosis in PAD patients. While rodents are being used to investigate PAD pathophysiology, imaging of these animal models has been underutilized. This review focuses on structural and molecular information and disease progression revealed by recent imaging efforts of aortic, cerebral, and peripheral vascular disease models in mice, rats, and rabbits. Effective translation to humans involves better understanding of underlying PAD pathophysiology to develop novel therapeutics and apply non-invasive imaging techniques in the clinic. PMID:25993289

  6. Subjective matters: from image quality to image psychology

    NASA Astrophysics Data System (ADS)

    Fedorovskaya, Elena A.; De Ridder, Huib

    2013-03-01

    From the advent of digital imaging through several decades of studies, the human vision research community systematically focused on perceived image quality and digital artifacts due to resolution, compression, gamma, dynamic range, capture and reproduction noise, blur, etc., to help overcome existing technological challenges and shortcomings. Technological advances made digital images and digital multimedia nearly flawless in quality, and ubiquitous and pervasive in usage, provide us with the exciting but at the same time demanding possibility to turn to the domain of human experience including higher psychological functions, such as cognition, emotion, awareness, social interaction, consciousness and Self. In this paper we will outline the evolution of human centered multidisciplinary studies related to imaging and propose steps and potential foci of future research.

  7. Image quality measures and their performance

    NASA Technical Reports Server (NTRS)

    Eskicioglu, Ahmet M.; Fisher, Paul S.; Chen, Si-Yuan

    1994-01-01

    A number of quality measures are evaluated for gray scale image compression. They are all bivariate exploiting the differences between corresponding pixels in the original and degraded images. It is shown that although some numerical measures correlate well with the observers' response for a given compression technique, they are not reliable for an evaluation across different techniques. The two graphical measures (histograms and Hosaka plots), however, can be used to appropriately specify not only the amount, but also the type of degradation in reconstructed images.

  8. Geometric assessment of image quality using digital image registration techniques

    NASA Technical Reports Server (NTRS)

    Tisdale, G. E.

    1976-01-01

    Image registration techniques were developed to perform a geometric quality assessment of multispectral and multitemporal image pairs. Based upon LANDSAT tapes, accuracies to a small fraction of a pixel were demonstrated. Because it is insensitive to the choice of registration areas, the technique is well suited to performance in an automatic system. It may be implemented at megapixel-per-second rates using a commercial minicomputer in combination with a special purpose digital preprocessor.

  9. Measuring image quality in overlapping areas of panoramic composed images

    NASA Astrophysics Data System (ADS)

    Mitjà, Carles; Bover, Toni; Escofet, Jaume

    2012-06-01

    Several professional photographic applications uses the merging of consecutive overlapping images in order to obtain bigger files by means of stitching techniques or extended field of view (FOV) for panoramic images. All of those applications share the fact that the final composed image is obtained by overlapping the neighboring areas of consecutive individual images taken as a mosaic or a series of tiles over the scene, from the same point of view. Any individual image taken with a given lens can carry residual aberrations and several of them will affect more probably the borders of the image frame. Furthermore, the amount of distortion aberration present in the images of a given lens will be reversed in position for the two overlapping areas of a pair of consecutive takings. Finally, the different images used in composing the final one have corresponding overlapping areas taken with different perspective. From all the previously stated can be derived that the software employed must remap all the pixel information in order to resize and match image features in those overlapping areas, providing a final composed image with the desired perspective projection. The work presented analyse two panoramic format images taken with a pair of lenses and composed by means of a state of the art stitching software. Then, a series of images are taken to cover an FOV three times the original lens FOV, the images are merged by means of a software of common use in professional panoramic photography and the final image quality is evaluated through a series of targets positioned in strategic locations over the whole taking field of view. That allows measuring the resulting Resolution and Modulation Transfer Function (MTF). The results are shown compared with the previous measures on the original individual images.

  10. FFDM image quality assessment using computerized image texture analysis

    NASA Astrophysics Data System (ADS)

    Berger, Rachelle; Carton, Ann-Katherine; Maidment, Andrew D. A.; Kontos, Despina

    2010-04-01

    Quantitative measures of image quality (IQ) are routinely obtained during the evaluation of imaging systems. These measures, however, do not necessarily correlate with the IQ of the actual clinical images, which can also be affected by factors such as patient positioning. No quantitative method currently exists to evaluate clinical IQ. Therefore, we investigated the potential of using computerized image texture analysis to quantitatively assess IQ. Our hypothesis is that image texture features can be used to assess IQ as a measure of the image signal-to-noise ratio (SNR). To test feasibility, the "Rachel" anthropomorphic breast phantom (Model 169, Gammex RMI) was imaged with a Senographe 2000D FFDM system (GE Healthcare) using 220 unique exposure settings (target/filter, kVs, and mAs combinations). The mAs were varied from 10%-300% of that required for an average glandular dose (AGD) of 1.8 mGy. A 2.5cm2 retroareolar region of interest (ROI) was segmented from each image. The SNR was computed from the ROIs segmented from images linear with dose (i.e., raw images) after flat-field and off-set correction. Image texture features of skewness, coarseness, contrast, energy, homogeneity, and fractal dimension were computed from the Premium ViewTM postprocessed image ROIs. Multiple linear regression demonstrated a strong association between the computed image texture features and SNR (R2=0.92, p<=0.001). When including kV, target and filter as additional predictor variables, a stronger association with SNR was observed (R2=0.95, p<=0.001). The strong associations indicate that computerized image texture analysis can be used to measure image SNR and potentially aid in automating IQ assessment as a component of the clinical workflow. Further work is underway to validate our findings in larger clinical datasets.

  11. Naturalness and interestingness of test images for visual quality evaluation

    NASA Astrophysics Data System (ADS)

    Halonen, Raisa; Westman, Stina; Oittinen, Pirkko

    2011-01-01

    Balanced and representative test images are needed to study perceived visual quality in various application domains. This study investigates naturalness and interestingness as image quality attributes in the context of test images. Taking a top-down approach we aim to find the dimensions which constitute naturalness and interestingness in test images and the relationship between these high-level quality attributes. We compare existing collections of test images (e.g. Sony sRGB images, ISO 12640 images, Kodak images, Nokia images and test images developed within our group) in an experiment combining quality sorting and structured interviews. Based on the data gathered we analyze the viewer-supplied criteria for naturalness and interestingness across image types, quality levels and judges. This study advances our understanding of subjective image quality criteria and enables the validation of current test images, furthering their development.

  12. Molecular histology of arteries: mass spectrometry imaging as a novel ex vivo tool to investigate atherosclerosis.

    PubMed

    Martin-Lorenzo, Marta; Alvarez-Llamas, Gloria; McDonnell, Liam A; Vivanco, Fernando

    2016-01-01

    Atherosclerosis is usually the underlying cause of a fatal event such as myocardial infarction or ictus. The atherome plaque develops silently and asymptomatically within the arterial intima layer. In this context, the possibility to analyze the molecular content of arterial tissue while preserving each molecule's specific localization is of great interest as it may reveal further insights into the physiopathological changes taking place. Mass spectrometry imaging (MSI) enables the spatially resolved molecular analysis of proteins, peptides, metabolites, lipids and drugs directly in tissue, with a resolution sufficient to reveal molecular features specific to distinct arterial structures. MSI represents a novel ex vivo imaging tool still underexplored in cardiovascular diseases. This review focuses on the MSI technique applied to cardiovascular disease and covers the main contributions to date, ongoing efforts, the main challenges and current limitations of MSI. PMID:26558814

  13. An Effect of Spatial Filtering in Visualization of Coronary Arteries Imaging

    E-print Network

    Kodge, B G

    2011-01-01

    At present, coronary angiography is the well known standard for the diagnosis of coronary artery disease. Conventional coronary angiography is an invasive procedure with a small, yet inherent risk of myocardial infarction, stroke, potential arrhythmias, and death. Other noninvasive diagnostic tools, such as electrocardiography, echocardiography, and nuclear imaging are now widely available but are limited by their inability to directly visualize and quantify coronary artery stenoses and predict the stability of plaques. Coronary magnetic resonance angiography (MRA) is a technique that allows visualization of the coronary arteries by noninvasive means; however, it has not yet reached a stage where it can be used in routine clinical practice. Although coronary MRA is a potentially useful diagnostic tool, it has limitations. Further research should focus on improving the diagnostic resolution and accuracy of coronary MRA. This paper will helps to cardiologists to take the clear look of spatial filtered imaging o...

  14. Understanding the genetics of coronary artery disease through the lens of non-invasive imaging

    PubMed Central

    Yang, Eunice; Vargas, Jose D

    2012-01-01

    Summary Coronary artery disease is a common disease with a known heritable component that has spurred interest in genetic research for decades, resulting in a handful of candidate genes and an appreciation for the complexity of its genetic contributions. Recent advances in sequencing technologies have made large scale association studies possible adding to our current understanding of the genetics of coronary artery disease. Sifting through the statistical noise, however, requires selecting effective phenotypic markers. New imaging technologies have improved our ability to detect subclinical atherosclerosis in a safe and reproducible manner in large numbers of patients. We propose here that advances in imaging technology have generated improved phenotypic markers for genetic association studies of coronary artery disease. PMID:22149524

  15. Regional calcium distribution and ultrasound images of the vessel wall in human carotid arteries

    NASA Astrophysics Data System (ADS)

    Szikszai, Z.; Kertész, Zs.; Uzonyi, I.; Szíki, G. Á.; Magyar, M. T.; Molnár, S.; Ida, Y.; Csiba, L.

    2005-04-01

    Arterial calcification can take place at two sites in the vessel wall: the intima and the media. Intimal calcification occurs exclusively within atherosclerotic plaques, while medial calcification may develop independently. Extensive calcified plaques in the carotid arteries can be easily detected by B-mode ultrasonic imaging. The calcium content might correlate with the ultrasound reflectance of the vessel wall, and could be a surrogate marker for arteriosclerosis. In this study, segments of human carotid arteries collected at autopsy were examined by ultrasonography in vitro and calcium distributional maps of sections from the same segments were determined by particle induced X-ray emission. Our aim was to make a first step towards investigating the relationship between the calcium distributional maps and the respective ultrasound images.

  16. Image Quality Indicator for Infrared Inspections

    NASA Technical Reports Server (NTRS)

    Burke, Eric

    2011-01-01

    The quality of images generated during an infrared thermal inspection depends on many system variables, settings, and parameters to include the focal length setting of the IR camera lens. If any relevant parameter is incorrect or sub-optimal, the resulting IR images will usually exhibit inherent unsharpness and lack of resolution. Traditional reference standards and image quality indicators (IQIs) are made of representative hardware samples and contain representative flaws of concern. These standards are used to verify that representative flaws can be detected with the current IR system settings. However, these traditional standards do not enable the operator to quantify the quality limitations of the resulting images, i.e. determine the inherent maximum image sensitivity and image resolution. As a result, the operator does not have the ability to optimize the IR inspection system prior to data acquisition. The innovative IQI described here eliminates this limitation and enables the operator to objectively quantify and optimize the relevant variables of the IR inspection system, resulting in enhanced image quality with consistency and repeatability in the inspection application. The IR IQI consists of various copper foil features of known sizes that are printed on a dielectric non-conductive board. The significant difference in thermal conductivity between the two materials ensures that each appears with a distinct grayscale or brightness in the resulting IR image. Therefore, the IR image of the IQI exhibits high contrast between the copper features and the underlying dielectric board, which is required to detect the edges of the various copper features. The copper features consist of individual elements of various shapes and sizes, or of element-pairs of known shapes and sizes and with known spacing between the elements creating the pair. For example, filled copper circles with various diameters can be used as individual elements to quantify the image sensitivity limit. Copper line-pairs of various sizes where the line width is equivalent to the spacing between the lines can be used as element-pairs to quantify the image resolution limit.

  17. Prediction of Viking lander camera image quality

    NASA Technical Reports Server (NTRS)

    Huck, F. O.; Burcher, E. E.; Jobson, D. J.; Wall, S. D.

    1976-01-01

    Formulations are presented that permit prediction of image quality as a function of camera performance, surface radiance properties, and lighting and viewing geometry. Predictions made for a wide range of surface radiance properties reveal that image quality depends strongly on proper camera dynamic range command and on favorable lighting and viewing geometry. Proper camera dynamic range commands depend mostly on the surface albedo that will be encountered. Favorable lighting and viewing geometries depend mostly on lander orientation with respect to the diurnal sun path over the landing site, and tend to be independent of surface albedo and illumination scattering function. Side lighting with low sun elevation angles (10 to 30 deg) is generally favorable for imaging spatial details and slopes, whereas high sun elevation angles are favorable for measuring spectral reflectances.

  18. Trans-illuminated laser speckle imaging of collateral artery blood flow in ischemic mouse hindlimb.

    PubMed

    Meisner, Joshua K; Niu, Jacqueline; Sumer, Suna; Price, Richard J

    2013-09-01

    The mouse ischemic hindlimb model is used widely for studying collateral artery growth (i.e., arteriogenesis) in response to increased shear stress. Nonetheless, precise measurements of regional shear stress changes along individual collateral arteries are lacking. Our goal is to develop and verify trans-illumination laser speckle flowmetry (LSF) for this purpose. Studies of defibrinated bovine blood flow through tubes embedded in tissue-mimicking phantoms indicate that trans-illumination LSF better maintains sensitivity with an increasing tissue depth when compared to epi-illumination, with an ?50% reduction in the exponential decay of the speckle velocity signal. Applying trans-illuminated LSF to the gracilis muscle collateral artery network in vivo yields both improved sensitivity and reduced noise when compared to epi-illumination. Trans-illuminated LSF images reveal regional differences in collateral artery blood velocity after femoral artery ligation and are used to measure an ?2-fold increase in the shear stress at the entrance regions to the muscle. We believe these represent the first direct measurements of regional shear stress changes in individual mouse collateral arteries. The ability to capture deeper vascular signals using a trans-illumination configuration for LSF may expand the current applications for LSF, which could have bearing on determining how shear stress magnitude and direction regulate arteriogenesis. PMID:24045691

  19. Surface Roughness Detection of Arteries via Texture Analysis of Ultrasound Images for Early Diagnosis of Atherosclerosis

    PubMed Central

    Niu, Lili; Qian, Ming; Yang, Wei; Meng, Long; Xiao, Yang; Wong, Kelvin K. L.; Abbott, Derek; Liu, Xin; Zheng, Hairong

    2013-01-01

    There is a strong research interest in identifying the surface roughness of the carotid arterial inner wall via texture analysis for early diagnosis of atherosclerosis. The purpose of this study is to assess the efficacy of texture analysis methods for identifying arterial roughness in the early stage of atherosclerosis. Ultrasound images of common carotid arteries of 15 normal mice fed a normal diet and 28 apoE?/? mice fed a high-fat diet were recorded by a high-frequency ultrasound system (Vevo 2100, frequency: 40 MHz). Six different texture feature sets were extracted based on the following methods: first-order statistics, fractal dimension texture analysis, spatial gray level dependence matrix, gray level difference statistics, the neighborhood gray tone difference matrix, and the statistical feature matrix. Statistical analysis indicates that 11 of 19 texture features can be used to distinguish between normal and abnormal groups (p<0.05). When the 11 optimal features were used as inputs to a support vector machine classifier, we achieved over 89% accuracy, 87% sensitivity and 93% specificity. The accuracy, sensitivity and specificity for the k-nearest neighbor classifier were 73%, 75% and 70%, respectively. The results show that it is feasible to identify arterial surface roughness based on texture features extracted from ultrasound images of the carotid arterial wall. This method is shown to be useful for early detection and diagnosis of atherosclerosis. PMID:24146940

  20. Imaging of Unilateral Meningo-ophthalmic Artery Anomaly in a Patient with Bilateral Nasopharyngeal Angiofibroma

    PubMed Central

    Louw, Louise; Steyl, Johan; Loggenberg, Eugene

    2014-01-01

    A 12-year-old boy with epistaxis presented with a rare midline nasopharyngeal angiofibroma that extended lateral into the pterygoid and infratemporal fossae. Pre-operative angiography revealed bilateral prominent feeder arteries and two major anastomotic connections, and a rare left meningo-ophthalmic artery (M-OA) anomaly that was the sole path of supply to the eye. A literature search using Pubmed and Medline was conducted. For imaging, a six-vessel study (i.e. external and internal carotid and vertebral arteries on both sides) was selected. Embolization of prominent tumor feeder arteries was unsafe for tumor extirpation, but super-selective embolization of both sphenopalatine arteries was performed to control epistaxis. The M-OA anomaly that originated from the maxillary artery (MA) was marked by an ophthalmic artery (OA) variant with orbital and ocular divisions that coursed through the superior orbital fissure and optic foramen, respectively, each with distinct branching patterns, a middle meningeal artery (MMA) with normal branches (i.e. anterior and posterior branches), and two branch variations (i.e. lacrimal and meningeal branches) that originated from the anterior branch of the MMA. The lacrimal branch coursed through a cranio-orbital foramen, but the meningeal branch remained outside the orbit. The anatomy of the right OA was normal. The left M-OA anomaly was considered incidental and not tumor-related since the tumor was more prominent on the right side, and no intra-orbital infiltrations occurred. Of clinical significance is that proximal embolization of MA or MMA carries a high risk of visual impairment in cases where M-OA anomalies are the sole mode of supply to the eye. PMID:25558432

  1. High resolution in vivo intra-arterial imaging with optical coherence tomography

    PubMed Central

    Fujimoto, J; Boppart, S; Tearney, G; Bouma, B; Pitris, C; Brezinski, M

    1999-01-01

    BACKGROUND—Optical coherence tomography (OCT) is a new method of catheter based micron scale imaging. OCT is analogous to ultrasound, measuring the intensity of backreflected infrared light rather than sound waves.?OBJECTIVE—To demonstrate the ability of OCT to perform high resolution imaging of arterial tissue in vivo.?METHODS—OCT imaging of the abdominal aorta of New Zealand white rabbits was performed using a 2.9 F OCT imaging catheter. Using an ultrashort pulse laser as a light source for imaging, an axial resolution of 10 µm was achieved.?RESULTS—Imaging was performed at 4 frames/second and data were saved in either super VHS or digital format. Saline injections were required during imaging because of the signal attenuation caused by blood. Microstructure was sharply defined within the arterial wall and correlated with histology. Some motion artefacts were noted at 4 frames/second.?CONCLUSIONS—In vivo imaging of the rabbit aorta was demonstrated at a source resolution of 10 µm, but required the displacement of blood with saline. The high resolution of OCT allows imaging to be performed near the resolution of histopathology, offering the potential to have an impact both on the identification of high risk plaques and the guidance of interventional procedures.???Keywords: imaging; intravascular ultrasound; plaque rupture; optical coherence tomography PMID:10409522

  2. Medical Imaging Image Quality Assessment with Monte Carlo Methods

    NASA Astrophysics Data System (ADS)

    Michail, C. M.; Karpetas, G. E.; Fountos, G. P.; Kalyvas, N. I.; Martini, Niki; Koukou, Vaia; Valais, I. G.; Kandarakis, I. S.

    2015-09-01

    The aim of the present study was to assess image quality of PET scanners through a thin layer chromatography (TLC) plane source. The source was simulated using a previously validated Monte Carlo model. The model was developed by using the GATE MC package and reconstructed images obtained with the STIR software for tomographic image reconstruction, with cluster computing. The PET scanner simulated in this study was the GE DiscoveryST. A plane source consisted of a TLC plate, was simulated by a layer of silica gel on aluminum (Al) foil substrates, immersed in 18F-FDG bath solution (1MBq). Image quality was assessed in terms of the Modulation Transfer Function (MTF). MTF curves were estimated from transverse reconstructed images of the plane source. Images were reconstructed by the maximum likelihood estimation (MLE)-OSMAPOSL algorithm. OSMAPOSL reconstruction was assessed by using various subsets (3 to 21) and iterations (1 to 20), as well as by using various beta (hyper) parameter values. MTF values were found to increase up to the 12th iteration whereas remain almost constant thereafter. MTF improves by using lower beta values. The simulated PET evaluation method based on the TLC plane source can be also useful in research for the further development of PET and SPECT scanners though GATE simulations.

  3. Dried fruits quality assessment by hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Serranti, Silvia; Gargiulo, Aldo; Bonifazi, Giuseppe

    2012-05-01

    Dried fruits products present different market values according to their quality. Such a quality is usually quantified in terms of freshness of the products, as well as presence of contaminants (pieces of shell, husk, and small stones), defects, mould and decays. The combination of these parameters, in terms of relative presence, represent a fundamental set of attributes conditioning dried fruits humans-senses-detectable-attributes (visual appearance, organolectic properties, etc.) and their overall quality in terms of marketable products. Sorting-selection strategies exist but sometimes they fail when a higher degree of detection is required especially if addressed to discriminate between dried fruits of relatively small dimensions and when aiming to perform an "early detection" of pathogen agents responsible of future moulds and decays development. Surface characteristics of dried fruits can be investigated by hyperspectral imaging (HSI). In this paper, specific and "ad hoc" applications addressed to propose quality detection logics, adopting a hyperspectral imaging (HSI) based approach, are described, compared and critically evaluated. Reflectance spectra of selected dried fruits (hazelnuts) of different quality and characterized by the presence of different contaminants and defects have been acquired by a laboratory device equipped with two HSI systems working in two different spectral ranges: visible-near infrared field (400-1000 nm) and near infrared field (1000-1700 nm). The spectra have been processed and results evaluated adopting both a simple and fast wavelength band ratio approach and a more sophisticated classification logic based on principal component (PCA) analysis.

  4. Imaging findings and endovascular management of iatrogenic hepatic arterial injuries

    PubMed Central

    Güneyli, Serkan; Gök, Mustafa; Ç?nar, Celal; Bozkaya, Halil; Korkmaz, Mehmet; Par?ldar, Mustafa; Oran, ?smail

    2015-01-01

    Iatrogenic hepatic arterial injuries (IHAIs) include pseudoaneurysm, extravasation, arteriovenous fistula, arteriobiliary fistula, and dissection. IHAIs are usually demonstrated following percutaneous transhepatic biliary drainage, percutaneous liver biopsy, liver surgery, chemoembolization, radioembolization, and endoscopic retrograde cholangiopancreatography. The latency period between the intervention and diagnosis varies. The most common symptom is hemorrhage, and the most common lesion is pseudoaneurysm. Computed tomography angiography (CTA) is mostly performed prior to angiography, and IHAIs are demonstrated on CTA in most of the patients. Patients with IHAI are mostly treated by coils, but some patients may be treated by liquid embolic materials or stent-grafts. CTA can also be used in the follow-up period. Endovascular treatment is a safe and minimally invasive treatment option with high success rates. PMID:26359873

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

    NASA Astrophysics Data System (ADS)

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

    2010-01-01

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

  6. Carotid artery and aortic arch imaging with ECG gating in DSA

    SciTech Connect

    Francis, D.A.; Sheldon, J.J.; Soila, K.; Tobias, J.

    1985-06-01

    New computer software for gated digital subtraction angiography imaging was used to study 57 patients over 3 months. Better mask registration on isolated sets of systolic and diastolic images improved image quality. Detail of vessel outline and lesion was better than that seen on nongated images.

  7. Objective Assessment of Image Quality VI: Imaging in Radiation Therapy

    PubMed Central

    Barrett, Harrison H.; Kupinski, Matthew A.; Müeller, Stefan; Halpern, Howard J.; Morris, John C.; Dwyer, Roisin

    2015-01-01

    Earlier work on Objective Assessment of Image Quality (OAIQ) focused largely on estimation or classification tasks in which the desired outcome of imaging is accurate diagnosis. This paper develops a general framework for assessing imaging quality on the basis of therapeutic outcomes rather than diagnostic performance. By analogy to Receiver Operating Characteristic (ROC) curves and their variants as used in diagnostic OAIQ, the method proposed here utilizes the Therapy Operating Characteristic or TOC curves, which are plots of the probability of tumor control vs. the probability of normal-tissue complications as the overall dose level of a radiotherapy treatment is varied. The proposed figure of merit is the area under the TOC curve, denoted AUTOC. This paper reviews an earlier exposition of the theory of TOC and AUTOC, which was specific to the assessment of image-segmentation algorithms, and extends it to other applications of imaging in external-beam radiation treatment as well as in treatment with internal radioactive sources. For each application, a methodology for computing the TOC is presented. A key difference between ROC and TOC is that the latter can be defined for a single patient rather than a population of patients. PMID:24200954

  8. The role of completion imaging following carotid artery endarterectomy.

    PubMed

    Ricco, Jean-Baptiste; Schneider, Fabrice; Illuminati, Giulio; Samson, Russell H

    2013-05-01

    A variety of completion imaging methods can be used during carotid endarterectomy to recognize technical errors or intrinsic abnormalities such as mural thrombus or platelet aggregation, but none of these methods has achieved wide acceptance, and their ability to improve the outcome of the operation remains a matter of controversy. It is unclear if completion imaging is routinely necessary and which abnormalities require re-exploration. Proponents of routine completion imaging argue that identification of these abnormalities will allow their immediate correction and avoid a perioperative stroke. However, much of the evidence in favor of this argument is incidental, and many experienced vascular surgeons who perform carotid endarterectomy do not use any completion imaging technique and report equally good outcomes using a careful surgical protocol. Furthermore, certain postoperative strokes, including intracerebral hemorrhage and hyperperfusion syndrome, are unrelated to the surgical technique and cannot be prevented by completion imaging. This controversial subject is now open to discussion, and our debaters have been given the task to clarify the evidence to justify their preferred option for completion imaging during carotid endarterectomy. PMID:23601598

  9. Differences in the Properties of the Radial Artery between Cun, Guan, Chi, and Nearby Segments Using Ultrasonographic Imaging: A Pilot Study on Arterial Depth, Diameter, and Blood Flow

    PubMed Central

    Kim, Jaeuk U.; Lee, Yu Jung; Kim, Jong Yeol

    2015-01-01

    Aim of the Study. The three conventional pulse-diagnostic palpation locations (PLs) on both wrists are Cun, Guan, and Chi, and each location reveals different clinical information. To identify anatomical or hemodynamic specificity, we used ultrasonographic imaging to determine the arterial diameter, radial artery depth, and arterial blood flow velocity at the three PLs and at nearby non-PL segments. Methods. We applied an ultrasound scanner to 44 subjects and studied the changes in the arterial diameter and depth as well as in the average/maximum blood flow velocities along the radial artery at three PLs and three non-PLs located more proximally than Chi. Results. All of the measurements at all of the PLs were significantly different (P < 0.01). Artery depth was significantly different among the non-PLs; however, this difference became insignificant after normalization to the arm circumference. Conclusions. Substantial changes in the hemodynamic and anatomical properties of the radial artery around the three PLs were insignificant at the nearby non-PLs segments. This finding may provide a partial explanation for the diagnostic use of “Cun, Guan, and Chi.” PMID:25763090

  10. Determination of lung segments in computed tomography images using the Euclidean distance to the pulmonary artery

    SciTech Connect

    Stoecker, Christina; Moltz, Jan H.; Lassen, Bianca; Kuhnigk, Jan-Martin; Krass, Stefan; Welter, Stefan; Peitgen, Heinz-Otto

    2013-09-15

    Purpose: Computed tomography (CT) imaging is the modality of choice for lung cancer diagnostics. With the increasing number of lung interventions on sublobar level in recent years, determining and visualizing pulmonary segments in CT images and, in oncological cases, reliable segment-related information about the location of tumors has become increasingly desirable. Computer-assisted identification of lung segments in CT images is subject of this work.Methods: The authors present a new interactive approach for the segmentation of lung segments that uses the Euclidean distance of each point in the lung to the segmental branches of the pulmonary artery. The aim is to analyze the potential of the method. Detailed manual pulmonary artery segmentations are used to achieve the best possible segment approximation results. A detailed description of the method and its evaluation on 11 CT scans from clinical routine are given.Results: An accuracy of 2–3 mm is measured for the segment boundaries computed by the pulmonary artery-based method. On average, maximum deviations of 8 mm are observed. 135 intersegmental pulmonary veins detected in the 11 test CT scans serve as reference data. Furthermore, a comparison of the presented pulmonary artery-based approach to a similar approach that uses the Euclidean distance to the segmental branches of the bronchial tree is presented. It shows a significantly higher accuracy for the pulmonary artery-based approach in lung regions at least 30 mm distal to the lung hilum.Conclusions: A pulmonary artery-based determination of lung segments in CT images is promising. In the tests, the pulmonary artery-based determination has been shown to be superior to the bronchial tree-based determination. The suitability of the segment approximation method for application in the planning of segment resections in clinical practice has already been verified in experimental cases. However, automation of the method accompanied by an evaluation on a larger number of test cases is required before application in the daily clinical routine.

  11. Hyperspectral and multispectral imaging for evaluating food safety and quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spectral imaging technologies have been developed rapidly during the past decade. This paper presents hyperspectral and multispectral imaging technologies in the area of food safety and quality evaluation, with an introduction, demonstration, and summarization of the spectral imaging techniques avai...

  12. Improving Secondary Ion Mass Spectrometry Image Quality with Image Fusion

    PubMed Central

    Tarolli, Jay G.; Jackson, Lauren M.; Winograd, Nicholas

    2014-01-01

    The spatial resolution of chemical images acquired with cluster secondary ion mass spectrometry (SIMS) is limited not only by the size of the probe utilized to create the images, but also by detection sensitivity. As the probe size is reduced to below 1 µm, for example, a low signal in each pixel limits lateral resolution due to counting statistics considerations. Although it can be useful to implement numerical methods to mitigate this problem, here we investigate the use of image fusion to combine information from scanning electron microscope (SEM) data with chemically resolved SIMS images. The advantage of this approach is that the higher intensity and, hence, spatial resolution of the electron images can help to improve the quality of the SIMS images without sacrificing chemical specificity. Using a pan-sharpening algorithm, the method is illustrated using synthetic data, experimental data acquired from a metallic grid sample, and experimental data acquired from a lawn of algae cells. The results show that up to an order of magnitude increase in spatial resolution is possible to achieve. A cross-correlation metric is utilized for evaluating the reliability of the procedure. PMID:24912432

  13. Model-based quantification of image quality

    NASA Technical Reports Server (NTRS)

    Hazra, Rajeeb; Miller, Keith W.; Park, Stephen K.

    1989-01-01

    In 1982, Park and Schowengerdt published an end-to-end analysis of a digital imaging system quantifying three principal degradation components: (1) image blur - blurring caused by the acquisition system, (2) aliasing - caused by insufficient sampling, and (3) reconstruction blur - blurring caused by the imperfect interpolative reconstruction. This analysis, which measures degradation as the square of the radiometric error, includes the sample-scene phase as an explicit random parameter and characterizes the image degradation caused by imperfect acquisition and reconstruction together with the effects of undersampling and random sample-scene phases. In a recent paper Mitchell and Netravelli displayed the visual effects of the above mentioned degradations and presented subjective analysis about their relative importance in determining image quality. The primary aim of the research is to use the analysis of Park and Schowengerdt to correlate their mathematical criteria for measuring image degradations with subjective visual criteria. Insight gained from this research can be exploited in the end-to-end design of optical systems, so that system parameters (transfer functions of the acquisition and display systems) can be designed relative to each other, to obtain the best possible results using quantitative measurements.

  14. Enhancement and quality control of GOES images

    NASA Astrophysics Data System (ADS)

    Jentoft-Nilsen, Marit; Palaniappan, Kannappan; Hasler, A. Frederick; Chesters, Dennis

    1996-10-01

    The new generation of Geostationary Operational Environmental Satellites (GOES) have an imager instrument with five multispectral bands of high spatial resolution,and very high dynamic range radiance measurements with 10-bit precision. A wide variety of environmental processes can be observed at unprecedented time scales using the new imager instrument. Quality assurance and feedback to the GOES project office is performed using rapid animation at high magnification, examining differences between successive frames, and applying radiometric and geometric correction algorithms. Missing or corrupted scanline data occur unpredictably due to noise in the ground based receiving system. Smooth high resolution noise-free animations can be recovered using automatic techniques even from scanline scratches affecting more than 25 percent of the dataset. Radiometric correction using the local solar zenith angle was applied to the visible channel to compensate for time- of-day illumination variations to produce gain-compensated movies that appear well-lit from dawn to dusk and extend the interval of useful image observations by more than two hours. A time series of brightness histograms displays some subtle quality control problems in the GOES channels related to rebinning of the radiance measurements. The human visual system is sensitive to only about half of the measured 10- bit dynamic range in intensity variations, at a given point in a monochrome image. In order to effectively use the additional bits of precision and handle the high data rate, new enhancement techniques and visualization tools were developed. We have implemented interactive image enhancement techniques to selectively emphasize different subranges of the 10-bits of intensity levels. Improving navigational accuracy using registration techniques and geometric correction of scanline interleaving errors is a more difficult problem that is currently being investigated.

  15. A study on automated anatomical labeling to arteries concerning with colon from 3D abdominal CT images

    NASA Astrophysics Data System (ADS)

    Hoang, Bui Huy; Oda, Masahiro; Jiang, Zhengang; Kitasaka, Takayuki; Misawa, Kazunari; Fujiwara, Michitaka; Mori, Kensaku

    2011-03-01

    This paper presents an automated anatomical labeling method of arteries extracted from contrasted 3D CT images based on multi-class AdaBoost. In abdominal surgery, understanding of vasculature related to a target organ such as the colon is very important. Therefore, the anatomical structure of blood vessels needs to be understood by computers in a system supporting abdominal surgery. There are several researches on automated anatomical labeling, but there is no research on automated anatomical labeling to arteries concerning with the colon. The proposed method obtains a tree structure of arteries from the artery region and calculates features values of each branch. These feature values are thickness, curvature, direction, and running vectors of branch. Then, candidate arterial names are computed by classifiers that are trained to output artery names. Finally, a global optimization process is applied to the candidate arterial names to determine final names. Target arteries of this paper are nine lower abdominal arteries (AO, LCIA, RCIA, LEIA, REIA, SMA, IMA, LIIA, RIIA). We applied the proposed method to 14 cases of 3D abdominal contrasted CT images, and evaluated the results by leave-one-out scheme. The average precision and recall rates of the proposed method were 87.9% and 93.3%, respectively. The results of this method are applicable for anatomical name display of surgical simulation and computer aided surgery.

  16. Accuracy of pulsed arterial spin labeling magnetic resonance imaging in the human brain : tag width and timing effects

    E-print Network

    Bolar, Divya Sanam

    2007-01-01

    Arterial spin labeling (ASL) is the only non-invasive magnetic resonance imaging (MRI) technique that allows absolute quantification of cerebral blood flow (CBF). It involves using radiofrequency pulses designed to invert ...

  17. Finger vein image quality evaluation using support vector machines

    NASA Astrophysics Data System (ADS)

    Yang, Lu; Yang, Gongping; Yin, Yilong; Xiao, Rongyang

    2013-02-01

    In an automatic finger-vein recognition system, finger-vein image quality is significant for segmentation, enhancement, and matching processes. In this paper, we propose a finger-vein image quality evaluation method using support vector machines (SVMs). We extract three features including the gradient, image contrast, and information capacity from the input image. An SVM model is built on the training images with annotated quality labels (i.e., high/low) and then applied to unseen images for quality evaluation. To resolve the class-imbalance problem in the training data, we perform oversampling for the minority class with random-synthetic minority oversampling technique. Cross-validation is also employed to verify the reliability and stability of the learned model. Our experimental results show the effectiveness of our method in evaluating the quality of finger-vein images, and by discarding low-quality images detected by our method, the overall finger-vein recognition performance is considerably improved.

  18. Quality of Life on Arterial Hypertension: Validity of Known Groups of MINICHAL

    PubMed Central

    Soutello, Ana Lúcia Soares; Rodrigues, Roberta Cunha Matheus; Jannuzzi, Fernanda Freire; São-João, Thaís Moreira; Martini, Gabriela Giordano; Nadruz Jr., Wilson; Gallani, Maria-Cecília Bueno Jayme

    2015-01-01

    Introductions In the care of hypertension, it is important that health professionals possess available tools that allow evaluating the impairment of the health-related quality of life, according to the severity of hypertension and the risk for cardiovascular events. Among the instruments developed for the assessment of health-related quality of life, there is the Mini-Cuestionario of Calidad de Vida en la Hipertensión Arterial (MINICHAL) recently adapted to the Brazilian culture. Objective To estimate the validity of known groups of the Brazilian version of the MINICHAL regarding the classification of risk for cardiovascular events, symptoms, severity of dyspnea and target-organ damage. Methods Data of 200 hypertensive outpatients concerning sociodemographic and clinical information and health-related quality of life were gathered by consulting the medical charts and the application of the Brazilian version of MINICHAL. The Mann-Whitney test was used to compare health-related quality of life in relation to symptoms and target-organ damage. The Kruskal-Wallis test and ANOVA with ranks transformation were used to compare health-related quality of life in relation to the classification of risk for cardiovascular events and intensity of dyspnea, respectively. Results The MINICHAL was able to discriminate health-related quality of life in relation to symptoms and kidney damage, but did not discriminate health-related quality of life in relation to the classification of risk for cardiovascular events. Conclusion The Brazilian version of the MINICHAL is a questionnaire capable of discriminating differences on the health?related quality of life regarding dyspnea, chest pain, palpitation, lipothymy, cephalea and renal damage. PMID:25993593

  19. Sexuality and Body Image After Uterine Artery Embolization and Hysterectomy in the Treatment of Uterine Fibroids: A Randomized Comparison

    SciTech Connect

    Hehenkamp, Wouter J. K. Volkers, Nicole A.; Bartholomeus, Wouter; Blok, Sjoerd de; Birnie, Erwin; Reekers, Jim A.; Ankum, Willem M.

    2007-09-15

    In this paper the effect of uterine artery embolization (UAE) on sexual functioning and body image is investigated in a randomized comparison to hysterectomy for symptomatic uterine fibroids. The EMbolization versus hysterectoMY (EMMY) trial is a randomized controlled study, conducted at 28 Dutch hospitals. Patients were allocated hysterectomy (n = 89) or UAE (n 88). Two validated questionnaires (the Sexual Activity Questionnaire [SAQ] and the Body Image Scale [BIS]) were completed by all patients at baseline, 6 weeks, and 6, 12, 18, and 24 months after treatment. Repeated measurements on SAQ scores revealed no differences between the groups. There was a trend toward improved sexual function in both groups at 2 years, although this failed to reach statistical significance except for the dimensions discomfort and habit in the UAE arm. Overall quality of sexual life deteriorated in a minority of cases at all time points, with no significant differences between the groups (at 24 months: UAE, 29.3%, versus hysterectomy, 23.5%; p = 0.32). At 24 months the BIS score had improved in both groups compared to baseline, but the change was only significant in the UAE group (p = 0.009). In conclusion, at 24 months no differences in sexuality and body image were observed between the UAE and the hysterectomy group. On average, both after UAE and hysterectomy sexual functioning and body image scores improved, but significantly so only after UAE.

  20. LETHA: Learning from High Quality Inputs for 3D Pose Estimation in Low Quality Images

    E-print Network

    Moreno-Noguer, Francesc

    LETHA: Learning from High Quality Inputs for 3D Pose Estimation in Low Quality Images Adrian Penate quality training data, and combining them with discriminative machine learning to deal with low- quality image with the 3D model [13]. Machine learning approaches on the other hand, annotate training imagery

  1. Quality initiatives: blind spots at brain imaging.

    PubMed

    Bahrami, Simin; Yim, Catherine M

    2009-11-01

    Radiologists face the daily challenge of analyzing and interpreting a high volume of images in a timely manner. Minimizing errors, whether perceptual or cognitive in nature, is paramount for high-quality diagnostics and patient care. There are certain areas within the head encountered at routine brain imaging in which the interpreting radiologist is most prone to make perceptual errors. These areas, or "blind spots," include the cerebral sulci, dural sinuses, orbits, cavernous sinuses, clivus, Meckel cave, brainstem, skull base, and parapharyngeal soft tissues. In addition, the use of an inappropriate window width and level for the evaluation of computed tomographic (CT) scans can be a virtual, rather than an anatomic, blind spot. The inclusion of a comprehensive checklist for evaluation of these blind spots as part of every brain imaging study is crucial for avoiding false-negative results. Knowledge of the anatomic features of these blind spots is also crucial, as well as familiarity with the normal CT and magnetic resonance imaging findings in these areas. In addition, the radiologist should be aware of possible interpretation pitfalls that may lead to false-positive results (eg, normal anatomic variants that may be mistaken for pathologic conditions). Finally, a well-developed differential diagnosis will help ensure correct interpretation and appropriate patient treatment. PMID:19734470

  2. Mechanical Stabilization of Mouse Carotid Artery for In Vivo Intravital Microscopy Imaging of Atherogenesis.

    PubMed

    Chèvre, Raphaël

    2015-01-01

    We present here a procedure that allows real-time high-resolution multichannel imaging of early atherosclerotic lesions of live mice, by dramatically reducing the respiratory and pulsatile movements of the athero-susceptible carotid artery, without significantly altering blood flow dynamics. This surgical preparation can be combined with the use of various fluorescent probes and reporter mice to simultaneously visualize the dynamics of inflammatory leukocytes, platelets, or even subcellular structures. Stabilization of the tissue renders it suitable for two-photon laser scanning microscopic imaging and allows tracking the behavior of inflammatory cells in three dimensions. PMID:26445802

  3. High-Permittivity Thin Dielectric Padding Improves Fresh Blood Imaging of Femoral Arteries at 3T

    PubMed Central

    Lindley, Marc D; Kim, Daniel; Morrell, Glen; Heilbrun, Marta E; Storey, Pippa; Hanrahan, Christopher J; Lee, Vivian S

    2014-01-01

    Objectives Fresh blood imaging (FBI) is a useful non-contrast magnetic resonance angiography (NC-MRA) method for assessment of peripheral arterial disease (PAD), particularly in patients with poor renal function. Compared with 1.5T, 3T enables higher signal to noise ratio (SNR) and/or spatio-temporal resolution in FBI, as demonstrated successfully for the calf station. However, FBI of the thigh station at 3T has been reported to suffer from signal void in the common femoral artery of one thigh only due to the radial symmetry in transmit radio-frequency field (B1+) variation. We sought to increase the femoral arterial signal attenuated by B1+ variation in FBI at 3T using high permittivity dielectric padding. Materials and Methods We performed FBI of the thigh station in 13 human subjects at 3T to compare the following 3 settings: no padding, commercially available thick (~ 5 cm) dielectric padding, and high-permittivity thin (~2 cm) dielectric padding. B1+ mapping was also performed in the common femoral arteries to characterize the radial symmetry in B1+ variation and quantify the improvement in B1+ excitation. We characterized the impact of radial symmetry in B1+ variation on the FBI signal and FBI MRA of the right common femoral artery using quantitative (i.e., contrast-to-noise ratio (CNR)) and qualitative (i.e., conspicuity) analyses. Results The radial symmetry in B1+ variation attenuates signal in the right common femoral artery, which can be partially improved with commercial padding and improved further with high permittivity padding. Averaging the results over 13 subjects, the B1+, CNR and conspicuity scores in the right common femoral artery were significantly better with high-permittivity padding than with commercial padding and baseline (p<0.001). Conclusions Our study shows that high-permittivity dielectric padding can be used to increase the femoral arterial signal attenuated by B1+ variation in FBI at 3T. PMID:25329606

  4. Tissue velocity imaging of coronary artery by rotating-type intravascular ultrasound.

    PubMed

    Saijo, Yoshifumi; Tanaka, Akira; Owada, Naoki; Akino, Yoshihisa; Nitta, Shinichi

    2004-04-01

    Intravascular ultrasound (IVUS) provides not only the dimensions of coronary artery but the information of tissue components. In catheterization laboratory, soft and hard plaques are classified by visual inspection of echo intensity. So-called soft plaque contains lipid core or thrombus and it is believed to be more vulnerable than a hard plaque. However, it is not simple to analyze the echo signals quantitatively. When we look at a reflection signal, the intensity is affected by the distance of the object, the medium between transducer and objects and the fluctuation caused by rotation of IVUS probe. The time of flight is also affected by the sound speed of the medium and Doppler shift caused by tissue motion but usually those can be neglected. Thus, the analysis of RF signal in time domain can be more quantitative than intensity of RF signal. In the present study, a novel imaging technique called "intravascular tissue velocity imaging" was developed for searching a vulnerable plaque. Radio-frequency (RF) signal from a clinically used IVUS apparatus was digitized at 500 MSa/s and stored in a workstation. First, non-uniform rotation was corrected by maximizing the correlation coefficient of circumferential RF signal distribution in two consecutive frames. Then, the correlation and displacement were calculated by analyzing the radial difference of RF signal. Tissue velocity was determined by the displacement and the frame rate. The correlation image of normal and atherosclerotic coronary arteries clearly showed the internal and external borders of arterial wall. Soft plaque with low echo area in the intima showed high velocity while the calcified lesion showed the very low tissue velocity. This technique provides important information on tissue character of coronary artery. PMID:15047378

  5. Quantitative optical imaging of vascular response in vivo in a model of peripheral arterial disease

    PubMed Central

    Poole, Kristin M.; Tucker-Schwartz, Jason M.; Sit, Wesley W.; Walsh, Alex J.; Duvall, Craig L.

    2013-01-01

    The mouse hind limb ischemia (HLI) model is well established for studying collateral vessel formation and testing therapies for peripheral arterial disease, but there is a lack of quantitative techniques for intravitally analyzing blood vessel structure and function. To address this need, non-invasive, quantitative optical imaging techniques were developed to assess the time-course of recovery in the mouse HLI model. Hyperspectral imaging and optical coherence tomography (OCT) were used to non-invasively image hemoglobin oxygen saturation and microvessel morphology plus blood flow, respectively, in the anesthetized mouse after induction of HLI. Hyperspectral imaging detected significant increases in hemoglobin saturation in the ischemic paw as early as 3 days after femoral artery ligation (P < 0.01), and significant increases in distal blood flow were first detected with OCT 14 days postsurgery (P < 0.01). Intravital OCT images of the adductor muscle vasculature revealed corkscrew collateral vessels characteristic of the arteriogenic response to HLI. The hyperspectral imaging and OCT data significantly correlated with each other and with laser Doppler perfusion imaging (LDPI) and tissue oxygenation sensor data (P < 0.01). However, OCT measurements acquired depth-resolved information and revealed more sustained flow deficits following surgery that may be masked by more superficial measurements (LDPI, hyperspectral imaging). Therefore, intravital OCT may provide a robust biomarker for the late stages of ischemic limb recovery. This work validates non-invasive acquisition of both functional and morphological data with hyperspectral imaging and OCT. Together, these techniques provide cardiovascular researchers an unprecedented and comprehensive view of the temporal dynamics of HLI recovery in living mice. PMID:23955718

  6. Image quality metrics for optical coherence angiography.

    PubMed

    Lozzi, Andrea; Agrawal, Anant; Boretsky, Adam; Welle, Cristin G; Hammer, Daniel X

    2015-07-01

    We characterized image quality in optical coherence angiography (OCA) en face planes of mouse cortical capillary network in terms of signal-to-noise ratio (SNR) and Weber contrast (Wc) through a novel mask-based segmentation method. The method was used to compare two adjacent B-scan processing algorithms, (1) average absolute difference (AAD) and (2) standard deviation (SD), while varying the number of lateral cross-sections acquired (also known as the gate length, N). AAD and SD are identical at N = 2 and exhibited similar image quality for N<10. However, AAD is relatively less susceptible to bulk tissue motion artifact than SD. SNR and Wc were 15% and 35% higher for AAD from N = 25 to 100. In addition data sets were acquired with two objective lenses with different magnifications to quantify the effect of lateral resolution on fine capillary detection. The lower power objective yielded a significant mean broadening of 17% in Full Width Half Maximum (FWHM) diameter. These results may guide study and device designs for OCA capillary and blood flow quantification. PMID:26203372

  7. Image quality metrics for optical coherence angiography

    PubMed Central

    Lozzi, Andrea; Agrawal, Anant; Boretsky, Adam; Welle, Cristin G.; Hammer, Daniel X.

    2015-01-01

    We characterized image quality in optical coherence angiography (OCA) en face planes of mouse cortical capillary network in terms of signal-to-noise ratio (SNR) and Weber contrast (Wc) through a novel mask-based segmentation method. The method was used to compare two adjacent B-scan processing algorithms, (1) average absolute difference (AAD) and (2) standard deviation (SD), while varying the number of lateral cross-sections acquired (also known as the gate length, N). AAD and SD are identical at N = 2 and exhibited similar image quality for N<10. However, AAD is relatively less susceptible to bulk tissue motion artifact than SD. SNR and Wc were 15% and 35% higher for AAD from N = 25 to 100. In addition data sets were acquired with two objective lenses with different magnifications to quantify the effect of lateral resolution on fine capillary detection. The lower power objective yielded a significant mean broadening of 17% in Full Width Half Maximum (FWHM) diameter. These results may guide study and device designs for OCA capillary and blood flow quantification. PMID:26203372

  8. Block-wise Finger Image Quality Assessment Based on Machine

    E-print Network

    Block-wise Finger Image Quality Assessment Based on Machine Learning Ivan Danov Kongens Lyngby 2013. These four machine learning models are used to predict the quality scores of the fingerprint images to extract quality features. These features are to be interpreted by another machine learning model trained

  9. Color Image Quality on the Internet Sabine Susstrunk, Stefan Winkler

    E-print Network

    Winkler, Stefan

    Color Image Quality on the Internet Sabine S¨usstrunk, Stefan Winkler Audiovisual Communications Laboratory (LCAV) Ecole Polytechnique F´ed´erale de Lausanne (EPFL) 1015 Lausanne, Switzerland ABSTRACT Color image quality depends on many factors, such as the initial capture system and its color image processing

  10. Objective assessment of image quality. IV. Application to adaptive optics

    E-print Network

    Dainty, Chris

    Objective assessment of image quality. IV. Application to adaptive optics Harrison H. Barrett J. Myers NIBIB/CDRH Laboratory for the Assessment of Medical Imaging Systems, Rockville, Maryland 14, 2006 (Doc. ID 65980) The methodology of objective assessment, which defines image quality

  11. Application-driven Spectral Image Quality Assessment and Prediction

    E-print Network

    Kerekes, John

    such as resolution, noise, and sharpness through a General Image Quality Equation (GIQE) [8]. These ratings found useApplication-driven Spectral Image Quality Assessment and Prediction John P. Kerekes Chester F. Carlson Center for Imaging Science Rochester Institute of Technology 54 Lomb Memorial Drive Rochester, New

  12. Measuring Images: Differences, Quality, and Appearance Garrett M. Johnson*

    E-print Network

    Johnson, Garrett M.

    Measuring Images: Differences, Quality, and Appearance Garrett M. Johnson* and Mark D. Fairchild Munsell Color Science Laboratory, Chester F. Carlson Center for Imaging Science, Rochester Institute of Technology, Rochester, NY, USA 14623-5604 ABSTRACT One goal of image quality modeling is to predict human

  13. Current and future trends in multimodality imaging of coronary artery disease.

    PubMed

    Alexanderson-Rosas, Erick; Guinto-Nishimura, Gerardo Y; Cruz-Mendoza, Jose Raul; Oropeza-Aguilar, Mariano; De La Fuente-Mancera, Juan Carlos; Barrero-Mier, Alejandro F; Monroy-Gonzalez, Andrea; Juarez-Orozco, Luis Eduardo; Cano-Zarate, Roberto; Meave-Gonzalez, Aloha

    2015-06-01

    Nowadays, there is a wide array of imaging studies available for the evaluation of coronary artery disease, each with its particular indications and strengths. Cardiac single photon emission tomography is mostly used to evaluate myocardial perfusion, having experienced recent marked improvements in image acquisition. Cardiac PET has its main utility in perfusion imaging, atherosclerosis and endothelial function evaluation, and viability assessment. Cardiovascular computed tomography has long been used as a reference test for non-invasive evaluation of coronary lesions and anatomic characterization. Cardiovascular magnetic resonance is currently the reference standard for non-invasive ventricular function evaluation and myocardial scarring delineation. These specific strengths have been enhanced with the advent of hybrid equipment, offering a true integration of different imaging modalities into a single, simultaneous and comprehensive study. PMID:25912725

  14. Non-linear imaging and characterization of atherosclerotic arterial tissue using combined SHG and FLIM microscopy

    NASA Astrophysics Data System (ADS)

    Cicchi, Riccardo; Matthäus, Christian; Meyer, Tobias; Lattermann, Annika; Dietzek, Benjamin; Brehm, Bernhard R.; Popp, Jürgen; Pavone, Francesco S.

    2015-03-01

    Atherosclerosis is among the most widespread cardiovascular diseases and one of the leading cause of death in the Western World. Characterization of arterial tissue in atherosclerotic condition is extremely interesting from the diagnostic point of view, especially for what is concerning collagen content and organization because collagen plays a crucial role in plaque vulnerability. Routinely used diagnostic methods, such as histopathological examination, are limited to morphological analysis of the examined tissues, whereas an exhaustive characterization requires immune-histochemical examination and a morpho-functional approach. Non-linear microscopy techniques offer the potential for providing morpho-functional information on the examined tissues in a label-free way. In this study, we employed combined SHG and FLIM microscopy for characterizing collagen organization in both normal arterial wall and within atherosclerotic plaques. Image pattern analysis of SHG images allowed characterizing collagen organization in different tissue regions. In addition, the analysis of collagen fluorescence decay contributed to the characterization of the samples on the basis of collagen fluorescence lifetime. Different values of collagen fiber mean size, collagen distribution, collagen anisotropy and collagen fluorescence lifetime were found in normal arterial wall and within plaque depositions, prospectively allowing for automated classification of atherosclerotic lesions and plaque vulnerability. The presented method represents a promising diagnostic tool for evaluating atherosclerotic tissue and has the potential to find a stable place in clinical setting as well as to be applied in vivo in the near future.

  15. Indocyanine green fluorescence and three-dimensional imaging of right gastroepiploic artery in gastric tube cancer

    PubMed Central

    Nakano, Toru; Sakurai, Tadashi; Maruyama, Shota; Ozawa, Yohei; Kamei, Takashi; Miyata, Go; Ohuchi, Noriaki

    2015-01-01

    A 79-year-old male was admitted to our hospital for the treatment of cancer of the gastric tube. Gastrointestinal examination revealed a T1b Union for International Cancer Control (UICC) tumor at the pyloric region of the gastric tube. Laparotomy did not reveal infiltration into the serosa, peritoneal dissemination, regional lymph node swelling, or distant metastasis. We performed a distal gastrectomy preserving the right gastroepiploic artery by referencing the preoperative three-dimensional computed tomoangiography. We also evaluated the blood flow of the right gastroepiploic artery and in the proximal gastric tube by using indocyanine green fluorescence imaging intra-operatively and then followed with a gastrojejunal anastomosis with Roux-en-Y reconstruction. The definitive diagnosis was moderately differentiated adenocarcinoma of the gastric tube, pT1bN0M0, pStage IA (UICC). His postoperative course was uneventful. Three-dimensional computed tomographic imaging is effective for assessing the course of blood vessels and the relationship with the surrounding structures. Intraoperative evaluation of blood flow of the right gastroepiploic artery and of the gastric tube in the anastomotic portion is very valuable information and could contribute to a safe gastrointestinal reconstruction. PMID:25574113

  16. The influence of statistical variations on image quality

    NASA Astrophysics Data System (ADS)

    Hultgren, Bror; Hertel, Dirk; Bullitt, Julian

    2006-01-01

    For more than thirty years imaging scientists have constructed metrics to predict psychovisually perceived image quality. Such metrics are based on a set of objectively measurable basis functions such as Noise Power Spectrum (NPS), Modulation Transfer Function (MTF), and characteristic curves of tone and color reproduction. Although these basis functions constitute a set of primitives that fully describe an imaging system from the standpoint of information theory, we found that in practical imaging systems the basis functions themselves are determined by system-specific primitives, i.e. technology parameters. In the example of a printer, MTF and NPS are largely determined by dot structure. In addition MTF is determined by color registration, and NPS by streaking and banding. Since any given imaging system is only a single representation of a class of more or less identical systems, the family of imaging systems and the single system are not described by a unique set of image primitives. For an image produced by a given imaging system, the set of image primitives describing that particular image will be a singular instantiation of the underlying statistical distribution of that primitive. If we know precisely the set of imaging primitives that describe the given image we should be able to predict its image quality. Since only the distributions are known, we can only predict the distribution in image quality for a given image as produced by the larger class of 'identical systems'. We will demonstrate the combinatorial effect of the underlying statistical variations in the image primitives on the objectively measured image quality of a population of printers as well as on the perceived image quality of a set of test images. We also will discuss the choice of test image sets and impact of scene content on the distribution of perceived image quality.

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

    SciTech Connect

    Rohkohl, Christopher; Bruder, Herbert; Stierstorfer, Karl; Flohr, Thomas

    2013-03-15

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

  18. Pseudoaneurysm of the femoral artery after cardiac catheterisation: diagnosis and treatment by manual compression guided by Doppler colour flow imaging.

    PubMed Central

    Currie, P; Turnbull, C M; Shaw, T R

    1994-01-01

    OBJECTIVE--To assess the value of Doppler colour flow imaging for diagnosing and guiding non-surgical treatment of pseudoaneurysm of the femoral artery complicating cardiac catheterisation. DESIGN--A prospective study. SETTING--Cardiac department in a teaching hospital. PATIENTS--9 patients (8 female, 1 male) who presented with pseudoaneurysm 1-15 days after cardiac catheterisation. INTERVENTIONS--The femoral arterial communication to the false aneurysm was localised by Doppler colour flow imaging. Manual pressure was then applied to the ultrasound transducer which was positioned directly over the site of the arterial communication. Pressure was progressively increased until it was sufficient to prevent colour flow from the artery into the false aneurysm cavity while allowing Doppler flow to continue within the arterial lumen. MAIN OUTCOME MEASURES--Characteristics of pseudoaneurysm, duration of manual compression, success rate, follow up. RESULTS--The pseudoaneurysms ranged from 1.3 to 5.5 cm in length. Six pseudoaneurysms were 1.3-2.0 cm away from the arterial puncture. The pseudoaneurysm was closed in 8/9 patients by compression exerted manually through the transducer for 25-40 minutes (3 successful cases required two or three periods of compression within 48 hours). No pseudoaneurysm recurred during 14-61 days of follow up. CONCLUSIONS--Most pseudoaneurysms of the femoral artery can be treated by a period of manual pressure applied with an ultrasound transducer and guided by Doppler colour flow. Images PMID:8068475

  19. Two-dimensional flow study in a stenotic artery phantom using ultrasonic particle image velocimetry.

    PubMed

    Qian, Ming; Song, Ruibo; Niu, Lili; Chen, Liping; Zheng, Hairong

    2011-01-01

    Blood flow dynamics has an important role in atherosclerosis initiation, progression, plaque rupture and thrombosis, and it is important to investigate the flow characteristics in the context of a mild stenotic artery. In this paper, tissue-equivalent ultrasound phantoms of artery stenosis were fabricated, and ultrasonic particle image velocimetry (EchoPIV) method was applied for two-dimensional flow study. A flow circuit was established and steady flow was provided by the gear pump. Flow at the inlet and the stenosis region were researched with EchoPIV method and ultrasound Doppler technique. The detailed 2D two-component velocity vectors were determined with EchoPIV method, and the measuring accuracy outweighs that of Ultrasound Doppler by comparing to the theoretical values of Poiseuille flow. PMID:22254372

  20. Quality Prediction of Asymmetrically Distorted Stereoscopic 3D Images.

    PubMed

    Wang, Jiheng; Rehman, Abdul; Zeng, Kai; Wang, Shiqi; Wang, Zhou

    2015-11-01

    Objective quality assessment of distorted stereoscopic images is a challenging problem, especially when the distortions in the left and right views are asymmetric. Existing studies suggest that simply averaging the quality of the left and right views well predicts the quality of symmetrically distorted stereoscopic images, but generates substantial prediction bias when applied to asymmetrically distorted stereoscopic images. In this paper, we first build a database that contains both single-view and symmetrically and asymmetrically distorted stereoscopic images. We then carry out a subjective test, where we find that the quality prediction bias of the asymmetrically distorted images could lean toward opposite directions (overestimate or underestimate), depending on the distortion types and levels. Our subjective test also suggests that eye dominance effect does not have strong impact on the visual quality decisions of stereoscopic images. Furthermore, we develop an information content and divisive normalization-based pooling scheme that improves upon structural similarity in estimating the quality of single-view images. Finally, we propose a binocular rivalry-inspired multi-scale model to predict the quality of stereoscopic images from that of the single-view images. Our results show that the proposed model, without explicitly identifying image distortion types, successfully eliminates the prediction bias, leading to significantly improved quality prediction of the stereoscopic images. PMID:26087491

  1. Performance evaluation of an automatic segmentation method of cerebral arteries in MRA images by use of a large image database

    NASA Astrophysics Data System (ADS)

    Uchiyama, Yoshikazu; Asano, Tatsunori; Hara, Takeshi; Fujita, Hiroshi; Kinosada, Yasutomi; Asano, Takahiko; Kato, Hiroki; Kanematsu, Masayuki; Hoshi, Hiroaki; Iwama, Toru

    2009-02-01

    The detection of cerebrovascular diseases such as unruptured aneurysm, stenosis, and occlusion is a major application of magnetic resonance angiography (MRA). However, their accurate detection is often difficult for radiologists. Therefore, several computer-aided diagnosis (CAD) schemes have been developed in order to assist radiologists with image interpretation. The purpose of this study was to develop a computerized method for segmenting cerebral arteries, which is an essential component of CAD schemes. For the segmentation of vessel regions, we first used a gray level transformation to calibrate voxel values. To adjust for variations in the positioning of patients, registration was subsequently employed to maximize the overlapping of the vessel regions in the target image and reference image. The vessel regions were then segmented from the background using gray-level thresholding and region growing techniques. Finally, rule-based schemes with features such as size, shape, and anatomical location were employed to distinguish between vessel regions and false positives. Our method was applied to 854 clinical cases obtained from two different hospitals. The segmentation of cerebral arteries in 97.1%(829/854) of the MRA studies was attained as an acceptable result. Therefore, our computerized method would be useful in CAD schemes for the detection of cerebrovascular diseases in MRA images.

  2. Rapid 3D dynamic arterial spin labeling with a sparse model-based image reconstruction.

    PubMed

    Zhao, Li; Fielden, Samuel W; Feng, Xue; Wintermark, Max; Mugler, John P; Meyer, Craig H

    2015-11-01

    Dynamic arterial spin labeling (ASL) MRI measures the perfusion bolus at multiple observation times and yields accurate estimates of cerebral blood flow in the presence of variations in arterial transit time. ASL has intrinsically low signal-to-noise ratio (SNR) and is sensitive to motion, so that extensive signal averaging is typically required, leading to long scan times for dynamic ASL. The goal of this study was to develop an accelerated dynamic ASL method with improved SNR and robustness to motion using a model-based image reconstruction that exploits the inherent sparsity of dynamic ASL data. The first component of this method is a single-shot 3D turbo spin echo spiral pulse sequence accelerated using a combination of parallel imaging and compressed sensing. This pulse sequence was then incorporated into a dynamic pseudo continuous ASL acquisition acquired at multiple observation times, and the resulting images were jointly reconstructed enforcing a model of potential perfusion time courses. Performance of the technique was verified using a numerical phantom and it was validated on normal volunteers on a 3-Tesla scanner. In simulation, a spatial sparsity constraint improved SNR and reduced estimation errors. Combined with a model-based sparsity constraint, the proposed method further improved SNR, reduced estimation error and suppressed motion artifacts. Experimentally, the proposed method resulted in significant improvements, with scan times as short as 20s per time point. These results suggest that the model-based image reconstruction enables rapid dynamic ASL with improved accuracy and robustness. PMID:26169322

  3. Learning to Rank for Blind Image Quality Assessment.

    PubMed

    Gao, Fei; Tao, Dacheng; Gao, Xinbo; Li, Xuelong

    2015-10-01

    Blind image quality assessment (BIQA) aims to predict perceptual image quality scores without access to reference images. State-of-the-art BIQA methods typically require subjects to score a large number of images to train a robust model. However, subjective quality scores are imprecise, biased, and inconsistent, and it is challenging to obtain a large-scale database, or to extend existing databases, because of the inconvenience of collecting images, training the subjects, conducting subjective experiments, and realigning human quality evaluations. To combat these limitations, this paper explores and exploits preference image pairs (PIPs) such as the quality of image Ia is better than that of image Ib for training a robust BIQA model. The preference label, representing the relative quality of two images, is generally precise and consistent, and is not sensitive to image content, distortion type, or subject identity; such PIPs can be generated at a very low cost. The proposed BIQA method is one of learning to rank. We first formulate the problem of learning the mapping from the image features to the preference label as one of classification. In particular, we investigate the utilization of a multiple kernel learning algorithm based on group lasso to provide a solution. A simple but effective strategy to estimate perceptual image quality scores is then presented. Experiments show that the proposed BIQA method is highly effective and achieves a performance comparable with that of state-of-the-art BIQA algorithms. Moreover, the proposed method can be easily extended to new distortion categories. PMID:25616080

  4. Three-dimensional segmentation of pulmonary artery volume from thoracic computed tomography imaging

    NASA Astrophysics Data System (ADS)

    Lindenmaier, Tamas J.; Sheikh, Khadija; Bluemke, Emma; Gyacskov, Igor; Mura, Marco; Licskai, Christopher; Mielniczuk, Lisa; Fenster, Aaron; Cunningham, Ian A.; Parraga, Grace

    2015-03-01

    Chronic obstructive pulmonary disease (COPD), is a major contributor to hospitalization and healthcare costs in North America. While the hallmark of COPD is airflow limitation, it is also associated with abnormalities of the cardiovascular system. Enlargement of the pulmonary artery (PA) is a morphological marker of pulmonary hypertension, and was previously shown to predict acute exacerbations using a one-dimensional diameter measurement of the main PA. We hypothesized that a three-dimensional (3D) quantification of PA size would be more sensitive than 1D methods and encompass morphological changes along the entire central pulmonary artery. Hence, we developed a 3D measurement of the main (MPA), left (LPA) and right (RPA) pulmonary arteries as well as total PA volume (TPAV) from thoracic CT images. This approach incorporates segmentation of pulmonary vessels in cross-section for the MPA, LPA and RPA to provide an estimate of their volumes. Three observers performed five repeated measurements for 15 ex-smokers with ?10 pack-years, and randomly identified from a larger dataset of 199 patients. There was a strong agreement (r2=0.76) for PA volume and PA diameter measurements, which was used as a gold standard. Observer measurements were strongly correlated and coefficients of variation for observer 1 (MPA:2%, LPA:3%, RPA:2%, TPA:2%) were not significantly different from observer 2 and 3 results. In conclusion, we generated manual 3D pulmonary artery volume measurements from thoracic CT images that can be performed with high reproducibility. Future work will involve automation for implementation in clinical workflows.

  5. Analysis of the Quality of Information Obtained About Uterine Artery Embolization From the Internet

    SciTech Connect

    Tavare, Aniket N.; Alsafi, Ali Hamady, Mohamad S.

    2012-12-15

    Purpose: The Internet is widely used by patients to source health care-related information. We sought to analyse the quality of information available on the Internet about uterine artery embolization (UAE). Materials and Methods: We searched three major search engines for the phrase 'uterine artery embolization' and compiled the top 50 results from each engine. After excluding repeated sites, scientific articles, and links to documents, the remaining 50 sites were assessed using the LIDA instrument, which scores sites across the domains of accessibility, usability, and reliability. The Fleisch reading ease score (FRES) was calculated for each of the sites. Finally, we checked the country of origin and the presence of certification by the Health On the Net Foundation (HONcode) as well as their effect on LIDA and FRES scores.ResultsThe following mean scores were obtained: accessibility 48/60 (80%), usability 42/54 (77%), reliability 20/51 (39%), total LIDA 110/165 (67%), and FRES 42/100 (42%). Nine sites had HONcode certification, and this was associated with significantly greater (p < 0.05) reliability and total LIDA and FRES scores. When comparing sites between United Kingdom and United States, there was marked variation in the quality of results obtained when searching for information on UAE (p < 0.05). Conclusion: In general, sites were well designed and easy to use. However, many scored poorly on the reliability of their information either because they were produced in a non-evidence-based way or because they lacking currency. It is important that patients are guided to reputable, location-specific sources of information online, especially because prominent search engine rank does not guarantee reliability of information.

  6. Retinal Image Quality during Accommodation in Adult Myopic Eyes

    PubMed Central

    Sreenivasan, Vidhyapriya; Aslakson, Emily; Kornaus, Andrew; Thibos, Larry N.

    2014-01-01

    Purpose Reduced retinal image contrast produced by accommodative lag is implicated with myopia development. Here, we measure accommodative error and retinal image quality from wavefront aberrations in myopes and emmetropes when they perform visually demanding and naturalistic tasks. Methods Wavefront aberrations were measured in 10 emmetropic and 11 myopic adults at three distances (100, 40, and 20 cm) while performing four tasks (monocular acuity, binocular acuity, reading, and movie watching). For the acuity tasks, measurements of wavefront error were obtained near the end point of the acuity experiment. Refractive state was defined as the target vergence that optimizes image quality using a visual contrast metric (VSMTF) computed from wavefront errors. Results Accommodation was most accurate (and image quality best) during binocular acuity whereas accommodation was least accurate (and image quality worst) while watching a movie. When viewing distance was reduced, accommodative lag increased and image quality (as quantified by VSMTF) declined for all tasks in both refractive groups. For any given viewing distance, computed image quality was consistently worse in myopes than in emmetropes, more so for the acuity than for reading/movie watching. Although myopes showed greater lags and worse image quality for the acuity experiments compared to emmetropes, acuity was not measurably worse in myopes compared to emmetropes. Conclusions Retinal image quality present when performing a visually demanding task (e.g., during clinical examination) is likely to be greater than for less demanding tasks (e.g., reading/movie watching). Although reductions in image quality lead to reductions in acuity, the image quality metric VSMTF is not necessarily an absolute indicator of visual performance because myopes achieved slightly better acuity than emmetropes despite showing greater lags and worse image quality. Reduced visual contrast in myopes compared to emmetropes is consistent with theories of myopia progression that point to image contrast as an inhibitory signal for ocular growth. PMID:24152885

  7. Automated registration of multispectral MR vessel wall images of the carotid artery

    SciTech Connect

    Klooster, R. van 't; Staring, M.; Reiber, J. H. C.; Lelieveldt, B. P. F.; Geest, R. J. van der; Klein, S.; Kwee, R. M.; Kooi, M. E.

    2013-12-15

    Purpose: Atherosclerosis is the primary cause of heart disease and stroke. The detailed assessment of atherosclerosis of the carotid artery requires high resolution imaging of the vessel wall using multiple MR sequences with different contrast weightings. These images allow manual or automated classification of plaque components inside the vessel wall. Automated classification requires all sequences to be in alignment, which is hampered by patient motion. In clinical practice, correction of this motion is performed manually. Previous studies applied automated image registration to correct for motion using only nondeformable transformation models and did not perform a detailed quantitative validation. The purpose of this study is to develop an automated accurate 3D registration method, and to extensively validate this method on a large set of patient data. In addition, the authors quantified patient motion during scanning to investigate the need for correction. Methods: MR imaging studies (1.5T, dedicated carotid surface coil, Philips) from 55 TIA/stroke patients with ipsilateral <70% carotid artery stenosis were randomly selected from a larger cohort. Five MR pulse sequences were acquired around the carotid bifurcation, each containing nine transverse slices: T1-weighted turbo field echo, time of flight, T2-weighted turbo spin-echo, and pre- and postcontrast T1-weighted turbo spin-echo images (T1W TSE). The images were manually segmented by delineating the lumen contour in each vessel wall sequence and were manually aligned by applying throughplane and inplane translations to the images. To find the optimal automatic image registration method, different masks, choice of the fixed image, different types of the mutual information image similarity metric, and transformation models including 3D deformable transformation models, were evaluated. Evaluation of the automatic registration results was performed by comparing the lumen segmentations of the fixed image and moving image after registration. Results: The average required manual translation per image slice was 1.33 mm. Translations were larger as the patient was longer inside the scanner. Manual alignment took 187.5 s per patient resulting in a mean surface distance of 0.271 ± 0.127 mm. After minimal user interaction to generate the mask in the fixed image, the remaining sequences are automatically registered with a computation time of 52.0 s per patient. The optimal registration strategy used a circular mask with a diameter of 10 mm, a 3D B-spline transformation model with a control point spacing of 15 mm, mutual information as image similarity metric, and the precontrast T1W TSE as fixed image. A mean surface distance of 0.288 ± 0.128 mm was obtained with these settings, which is very close to the accuracy of the manual alignment procedure. The exact registration parameters and software were made publicly available. Conclusions: An automated registration method was developed and optimized, only needing two mouse clicks to mark the start and end point of the artery. Validation on a large group of patients showed that automated image registration has similar accuracy as the manual alignment procedure, substantially reducing the amount of user interactions needed, and is multiple times faster. In conclusion, the authors believe that the proposed automated method can replace the current manual procedure, thereby reducing the time to analyze the images.

  8. High-Resolution Magnetic Resonance Imaging of Intracranial Vertebral Artery Dissecting Aneurysm for Planning of Endovascular Treatment

    PubMed Central

    Chun, Dong Hyun; Jeong, Young Gyun; Jeong, Hae Woong

    2015-01-01

    The equipment and techniques associated with magnetic resonance imaging (MRI) have rapidly evolved. The development of 3.0 Tesla MRI has enabled high-resolution imaging of the intracranial vessel wall. High-resolution MRI (HRMRI) can yield excellent visualization of both the arterial wall and lumen, thus facilitating the detection of the primary and secondary features of intracranial arterial dissection. In the present report, we describe the manner in which HRMRI affected our endovascular treatment planning strategy in 2 cases with unruptured intracranial vertebral artery dissection aneurysm. HRMRI provides further information about the vessel wall and the lumen of the unruptured intracranial vertebral artery dissecting aneurysm, which was treated by an endovascular approach in the 2 current cases. PMID:26361535

  9. 19 me Congrs Franais de Mcanique Marseille, 24-28 aot 2009 CFD-based functional imaging for arteries : in vitro validation

    E-print Network

    Nicoud, Franck

    for arteries : in vitro validation B. TAYLLAMINa, R. MORENOb, F. NICOUDa, M. CHAUc, H. ROUSSEAUb a. I3M CNRS for arteries. The relevant data (velocity field, wall shear stress, pressure gradient, ...) are the output distribution and biomechanical load on the arterial wall. Nevertheless there no doubt that medical imaging

  10. High-Resolution 3 T MR Microscopy Imaging of Arterial Walls

    SciTech Connect

    Sailer, Johannes Rand, Thomas; Berg, Andreas; Sulzbacher, Irene; Peloschek, P.; Hoelzenbein, Thomas; Lammer, Johannes

    2006-10-15

    Purpose. To achieve a high spatial resolution in MR imaging that allows for clear visualization of anatomy and even histology and documentation of plaque morphology in in vitro samples from patients with advanced atherosclerosis. A further objective of our study was to evaluate whether T2-weighted high-resolution MR imaging can provide accurate classification of atherosclerotic plaque according to a modified American Heart Association classification. Methods. T2-weighted images of arteries were obtained in 13 in vitro specimens using a 3 T MR unit (Medspec 300 Avance/Bruker, Ettlingen, Germany) combined with a dedicated MR microscopy system. Measurement parameters were: T2-weighted sequences with TR 3.5 sec, TE 15-120 msec; field of view (FOV) 1.4 x 1.4; NEX 8; matrix 192; and slice thickness 600 {mu}m. MR measurements were compared with corresponding histologic sections. Results. We achieved excellent spatial and contrast resolution in all specimens. We found high agreement between MR images and histology with regard to the morphology and extent of intimal proliferations in all but 2 specimens. We could differentiate fibrous caps and calcifications from lipid plaque components based on differences in signal intensity in order to differentiate hard and soft atheromatous plaques. Hard plaques with predominantly intimal calcifications were found in 7 specimens, and soft plaques with a cholesterol/lipid content in 5 cases. In all specimens, hemorrhage or thrombus formation, and fibrotic and hyalinized tissue could be detected on both MR imaging and histopathology. Conclusion. High-resolution, high-field MR imaging of arterial walls demonstrates the morphologic features, volume, and extent of intimal proliferations with high spatial and contrast resolution in in vitro specimens and can differentiate hard and soft plaques.

  11. Searching for the limit of image quality in film radiography

    SciTech Connect

    Vaessen, B.; Perdieus, P.; Florens, R.

    1993-12-31

    Radiographic film image quality in general was, and in most cases still is, considered as a very subjective and rather vague parameter. Yet it is of vital importance to the NDT and related quality control and quality assurance industry. Therefore, lately Agfa has put a major effort into quantifying image quality in an objective, measurable way. It was in the framework of this optimization project, that the authors, based on these new insights in imaging of industrial film systems, strived to search for the limit of the highest achievable image quality. In this paper they report these results. They not only report these results in an academic way, meaning how this highest image quality can be achieved under lab conditions, but also how these same results can be obtained under practical e.g. field-conditions.

  12. Food quality assessment by NIR hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Whitworth, Martin B.; Millar, Samuel J.; Chau, Astor

    2010-04-01

    Near infrared reflectance (NIR) spectroscopy is well established in the food industry for rapid compositional analysis of bulk samples. NIR hyperspectral imaging provides new opportunities to measure the spatial distribution of components such as moisture and fat, and to identify and measure specific regions of composite samples. An NIR hyperspectral imaging system has been constructed for food research applications, incorporating a SWIR camera with a cooled 14 bit HgCdTe detector and N25E spectrograph (Specim Ltd, Finland). Samples are scanned in a pushbroom mode using a motorised stage. The system has a spectral resolution of 256 pixels covering a range of 970-2500 nm and a spatial resolution of 320 pixels covering a swathe adjustable from 8 to 300 mm. Images are acquired at a rate of up to 100 lines s-1, enabling samples to be scanned within a few seconds. Data are captured using SpectralCube software (Specim) and analysed using ENVI and IDL (ITT Visual Information Solutions). Several food applications are presented. The strength of individual absorbance bands enables the distribution of particular components to be assessed. Examples are shown for detection of added gluten in wheat flour and to study the effect of processing conditions on fat distribution in chips/French fries. More detailed quantitative calibrations have been developed to study evolution of the moisture distribution in baguettes during storage at different humidities, to assess freshness of fish using measurements of whole cod and fillets, and for prediction of beef quality by identification and separate measurement of lean and fat regions.

  13. Improved factor analysis of dynamic PET images to estimate arterial input function and tissue curves

    NASA Astrophysics Data System (ADS)

    Boutchko, Rostyslav; Mitra, Debasis; Pan, Hui; Jagust, William; Gullberg, Grant T.

    2015-03-01

    Factor analysis of dynamic structures (FADS) is a methodology of extracting time-activity curves (TACs) for corresponding different tissue types from noisy dynamic images. The challenges of FADS include long computation time and sensitivity to the initial guess, resulting in convergence to local minima far from the true solution. We propose a method of accelerating and stabilizing FADS application to sequences of dynamic PET images by adding preliminary cluster analysis of the time activity curves for individual voxels. We treat the temporal variation of individual voxel concentrations as a set of time-series and use a partial clustering analysis to identify the types of voxel TACs that are most functionally distinct from each other. These TACs provide a good initial guess for the temporal factors for subsequent FADS processing. Applying this approach to a set of single slices of dynamic 11C-PIB images of the brain allows identification of the arterial input function and two different tissue TACs that are likely to correspond to the specific and non-specific tracer binding-tissue types. These results enable us to perform direct classification of tissues based on their pharmacokinetic properties in dynamic PET without relying on a compartment-based kinetic model, without identification of the reference region, or without using any external methods of estimating the arterial input function, as needed in some techniques.

  14. Plaque Imaging to Decide on Optimal Treatment: Medical Versus Carotid Endarterectomy Versus Carotid Artery Stenting.

    PubMed

    Sun, Jie; Hatsukami, Thomas S

    2016-02-01

    Many of the current guidelines for the management of carotid atherosclerosis are based on clinical trial findings published more than 2 decades ago. The lack of plaque information in clinical decision making represents a major shortcoming and highlights the need for contemporary trials based on characteristics of the atherosclerotic lesion itself, rather than luminal stenosis alone. This article summarizes the major dilemmas clinicians face in current practice, and discusses the rationale and evidence that plaque imaging may help to address these challenges and optimize the clinical management of carotid artery disease in the future. PMID:26610667

  15. Influence of affective image content on subjective quality assessment.

    PubMed

    van der Linde, Ian; Doe, Rachel M

    2012-09-01

    Image quality assessment (IQA) enables distortions introduced into an image (e.g., through lossy compression or broadcast) to be measured and evaluated for severity. It is unclear to what degree affective image content may influence this process. In this study, participants (n=25) were found to be unable to disentangle affective image content from objective image quality in a standard IQA procedure (single stimulus numerical categorical scale). We propose that this issue is worthy of consideration, particularly in single stimulus IQA techniques, in which a small number of handpicked images, not necessarily representative of the gamut of affect seen in true broadcasting, and unrated for affective content, serve as stimuli. PMID:23201952

  16. Diagnostic Confidence of Run-Off CT-Angiography as the Primary Diagnostic Imaging Modality in Patients Presenting with Acute or Chronic Peripheral Arterial Disease

    PubMed Central

    Werncke, Thomas; Ringe, Kristina Imeen; von Falck, Christian; Kruschewski, Martin; Wacker, Frank; Meyer, Bernhard Christian

    2015-01-01

    Objectives To investigate the reliability of CT-angiography of the lower extremities (run-off CTA) to derive a treatment decision in patients with acute and chronic peripheral artery disease (PAD). Materials and Methods 314 patients referred for run-off CTA were includ-ed in this retrospective study. First, diagnostic confidence of run-off CTA to derive a treat-ment decision was assessed in an interdisciplinary vascular conference using a 2 point scale (sufficient or not sufficient diagnostic confidence) and compared with the image quality eval-uated by two readers in consensus in four different levels (abdominopelvic, thigh, calf, foot arteries). Second, reliability of treatment decision was verified in all patients undergoing re-vascularization therapy. Results Diagnostic confidence of run-off CTA to derive a treatment deci-sion was sufficient in all patients with acute and in 97% of patients (215/221) with chronic PAD, whereas the rate of run-off CTA with non-diagnostic image quality was considerably higher in the calf and foot level (acute vs. chronic; calf: 28% vs.17%; foot: 52% vs. 20%). Reliability of treatment decision was superior for patients with chronic (123/133 = 92%) than for patients with acute PAD (64/78 = 82%, P = 0.02). Conclusion Run-off CTA is a reliable imaging modality for primary diag-nostic work-up of patients with acute and chronic PAD. PMID:25835948

  17. Automated FMV image quality assessment based on power spectrum statistics

    NASA Astrophysics Data System (ADS)

    Kalukin, Andrew

    2015-05-01

    Factors that degrade image quality in video and other sensor collections, such as noise, blurring, and poor resolution, also affect the spatial power spectrum of imagery. Prior research in human vision and image science from the last few decades has shown that the image power spectrum can be useful for assessing the quality of static images. The research in this article explores the possibility of using the image power spectrum to automatically evaluate full-motion video (FMV) imagery frame by frame. This procedure makes it possible to identify anomalous images and scene changes, and to keep track of gradual changes in quality as collection progresses. This article will describe a method to apply power spectral image quality metrics for images subjected to simulated blurring, blocking, and noise. As a preliminary test on videos from multiple sources, image quality measurements for image frames from 185 videos are compared to analyst ratings based on ground sampling distance. The goal of the research is to develop an automated system for tracking image quality during real-time collection, and to assign ratings to video clips for long-term storage, calibrated to standards such as the National Imagery Interpretability Rating System (NIIRS).

  18. Sectioned images and surface models of a cadaver for understanding the deep circumflex iliac artery flap.

    PubMed

    Kim, Bong Chul; Chung, Min Suk; Kim, Hyung Jun; Park, Jin Seo; Shin, Dong Sun

    2014-03-01

    The aim of this study was to describe the deep circumflex iliac artery (DCIA) flap from sectioned images and stereoscopic anatomic models using Visible Korean, for the benefit of medical education and clinical training in the field of oromandibular reconstructive surgery. Serially sectioned images of the pelvic area were obtained from a cadaver. Outlines of significant structures in the sectioned images were drawn and stacked to build surface models. The PDF (portable document format) file (size, 30 MB) of the constructed models is available for free download on the Web site of the Department of Anatomy at Ajou University School of Medicine (http://anatomy.co.kr). In the PDF file, the relevant structures of the DCIA flap can be seen in the sectioned images. All surface models and stereoscopic structures associated with the DCIA flap are displayed in real time. We hope that these state-of-the-art sectioned images, outlined images, and surface models will help students and trainees better understand the anatomy associated with DCIA flap. PMID:24621709

  19. Lighting Estimation in Indoor Environments from Low-Quality Images

    E-print Network

    Wolf, Christian

    Lighting Estimation in Indoor Environments from Low-Quality Images Natalia Neverova, Damien Muselet iterative algorithm allowing to estimate light colors in low-quality images. Sec- ond, unlike the classical.muselet,alain.tremeau}@univ-st-etienne.fr http://laboratoirehubertcurien.fr Abstract. Lighting conditions estimation is a crucial point in many

  20. Can pictorial images communicate the quality of pain successfully?

    PubMed Central

    Knapp, Peter; Morley, Stephen; Stones, Catherine

    2015-01-01

    Chronic pain is common and difficult for patients to communicate to health professionals. It may include neuropathic elements which require specialised treatment. A little used approach to communicating the quality of pain is through the use of images. This study aimed to test the ability of a set of 12 images depicting different sensory pain qualities to successfully communicate those qualities. Images were presented to 25 student nurses and 38 design students. Students were asked to write down words or phrases describing the quality of pain they felt was being communicated by each image. They were asked to provide as many or as few as occurred to them. The images were extremely heterogeneous in their ability to convey qualities of pain accurately. Only 2 of the 12 images were correctly interpreted by more than 70% of the sample. There was a significant difference between the two student groups, with nurses being significantly better at interpreting the images than the design students. Clearly, attention needs to be given not only to the content of images designed to depict the sensory qualities of pain but also to the differing audiences who may use them. Education, verbal ability, ethnicity and a multiplicity of other factors may influence the understanding and use of such images. Considerable work is needed to develop a set of images which is sufficiently culturally appropriate and effective for general use. PMID:26516574

  1. The Quality of Reports on Cervical Arterial Dissection following Cervical Spinal Manipulation

    PubMed Central

    Wynd, Shari; Westaway, Michael; Vohra, Sunita; Kawchuk, Greg

    2013-01-01

    Background Cervical artery dissection (CAD) and stroke are serious harms that are sometimes associated with cervical spinal manipulation therapy (cSMT). Because of the relative rarity of these adverse events, studying them prospectively is challenging. As a result, systematic review of reports describing these events offers an important opportunity to better understand the relation between adverse events and cSMT. Of note, the quality of the case report literature in this area has not yet been assessed. Purpose 1) To systematically collect and synthesize available reports of CAD that have been associated with cSMT in the literature and 2) assess the quality of these reports. Methods A systematic review of the literature was conducted using several databases. All clinical study designs involving CADs associated with cSMT were eligible for inclusion. Included studies were screened by two independent reviewers for the presence/absence of 11 factors considered to be important in understanding the relation between CAD and cSMT. Results Overall, 43 articles reported 901 cases of CAD and 707 incidents of stroke reported to be associated with cSMT. The most common type of stroke reported was ischemic stroke (92%). Time-to-onset of symptoms was reported most frequently (95%). No single case included all 11 factors. Conclusions This study has demonstrated that the literature infrequently reports useful data toward understanding the association between cSMT, CADs and stroke. Improving the quality, completeness, and consistency of reporting adverse events may improve our understanding of this important relation. PMID:23527121

  2. Quaternion structural similarity: a new quality index for color images.

    PubMed

    Kolaman, Amir; Yadid-Pecht, Orly

    2012-04-01

    One of the most important issues for researchers developing image processing algorithms is image quality. Methodical quality evaluation, by showing images to several human observers, is slow, expensive, and highly subjective. On the other hand, a visual quality matrix (VQM) is a fast, cheap, and objective tool for evaluating image quality. Although most VQMs are good in predicting the quality of an image degraded by a single degradation, they poorly perform for a combination of two degradations. An example for such degradation is the color crosstalk (CTK) effect, which introduces blur with desaturation. CTK is expected to become a bigger issue in image quality as the industry moves toward smaller sensors. In this paper, we will develop a VQM that will be able to better evaluate the quality of an image degraded by a combined blur/desaturation degradation and perform as well as other VQMs on single degradations such as blur, compression, and noise. We show why standard scalar techniques are insufficient to measure a combined blur/desaturation degradation and explain why a vectorial approach is better suited. We introduce quaternion image processing (QIP), which is a true vectorial approach and has many uses in the fields of physics and engineering. Our new VQM is a vectorial expansion of structure similarity using QIP, which gave it its name-Quaternion Structural SIMilarity (QSSIM). We built a new database of a combined blur/desaturation degradation and conducted a quality survey with human subjects. An extensive comparison between QSSIM and other VQMs on several image quality databases-including our new database-shows the superiority of this new approach in predicting visual quality of color images. PMID:22203713

  3. Image processing system performance prediction and product quality evaluation

    NASA Technical Reports Server (NTRS)

    Stein, E. K.; Hammill, H. B. (principal investigators)

    1976-01-01

    The author has identified the following significant results. A new technique for image processing system performance prediction and product quality evaluation was developed. It was entirely objective, quantitative, and general, and should prove useful in system design and quality control. The technique and its application to determination of quality control procedures for the Earth Resources Technology Satellite NASA Data Processing Facility are described.

  4. Machine vision image quality measurement in cardiac x-ray imaging

    NASA Astrophysics Data System (ADS)

    Kengyelics, Stephen M.; Gislason-Lee, Amber; Keeble, Claire; Magee, Derek; Davies, Andrew G.

    2015-03-01

    The purpose of this work is to report on a machine vision approach for the automated measurement of x-ray image contrast of coronary arteries filled with iodine contrast media during interventional cardiac procedures. A machine vision algorithm was developed that creates a binary mask of the principal vessels of the coronary artery tree by thresholding a standard deviation map of the direction image of the cardiac scene derived using a Frangi filter. Using the mask, average contrast is calculated by fitting a Gaussian model to the greyscale profile orthogonal to the vessel centre line at a number of points along the vessel. The algorithm was applied to sections of single image frames from 30 left and 30 right coronary artery image sequences from different patients. Manual measurements of average contrast were also performed on the same images. A Bland-Altman analysis indicates good agreement between the two methods with 95% confidence intervals -0.046 to +0.048 with a mean bias of 0.001. The machine vision algorithm has the potential of providing real-time context sensitive information so that radiographic imaging control parameters could be adjusted on the basis of clinically relevant image content.

  5. Coronary artery wall imaging in mice using osmium tetroxide and micro-computed tomography (micro-CT)

    SciTech Connect

    Pai, Vinay M.; Kozlowski, Megan; Donahue, Danielle; Miller, Elishiah; Xiao, Xianghui; Chen, Marcus Y.; Yu, Zu-Xi; Connelly, Patricia; Jeffries, Kenneth; Wen, Han

    2012-05-10

    The high spatial resolution of micro-computed tomography (micro-CT) is ideal for 3D imaging of coronary arteries in intact mouse heart specimens. Previously, micro-CT of mouse heart specimens utilized intravascular contrast agents that hardened within the vessel lumen and allowed a vascular cast to be made. However, for mouse coronary artery disease models, it is highly desirable to image coronary artery walls and highlight plaques. For this purpose, we describe an ex vivo contrast-enhanced micro-CT imaging technique based on tissue staining with osmium tetroxide (OsO{sub 4}) solution. As a tissue-staining contrast agent, OsO{sub 4} is retained in the vessel wall and surrounding tissue during the fixation process and cleared from the vessel lumens. Its high X-ray attenuation makes the artery wall visible in CT. Additionally, since OsO{sub 4} preferentially binds to lipids, it highlights lipid deposition in the artery wall. We performed micro-CT of heart specimens of 5- to 25-week-old C57BL/6 wild-type mice and 5- to 13-week-old apolipoprotein E knockout (apoE{sup -/-}) mice at 10 {mu}m resolution. The results show that walls of coronary arteries as small as 45 {mu}m in diameter are visible using a table-top micro-CT scanner. Similar image clarity was achieved with 1/2000th the scan time using a synchrotron CT scanner. In 13-week-old apoE mice, lipid-rich plaques are visible in the aorta. Our study shows that the combination of OsO{sub 4} and micro-CT permits the visualization of the coronary artery wall in intact mouse hearts.

  6. Screen-imaging guidance using a modified portable video macroscope for middle cerebral artery occlusion.

    PubMed

    Zhu, Xingbao; Luo, Junli; Liu, Yun; Chen, Guolong; Liu, Song; Ruan, Qiangjin; Deng, Xunding; Wang, Dianchun; Fan, Quanshui; Pan, Xinghua

    2012-04-25

    The use of operating microscopes is limited by the focal length. Surgeons using these instruments cannot simultaneously view and access the surgical field and must choose one or the other. The longer focal length (more than 1 000 mm) of an operating telescope permits a position away from the operating field, above the surgeon and out of the field of view. This gives the telescope an advantage over an operating microscope. We developed a telescopic system using screen-imaging guidance and a modified portable video macroscope constructed from a Computar MLH-10 × macro lens, a DFK-21AU04 USB CCD Camera and a Dell laptop computer as monitor screen. This system was used to establish a middle cerebral artery occlusion model in rats. Results showed that magnification of the modified portable video macroscope was appropriate (5-20 ×) even though the Computar MLH-10 × macro lens was placed 800 mm away from the operating field rather than at the specified working distance of 152.4 mm with a zoom of 1-40 ×. The screen-imaging telescopic technique was clear, life-like, stereoscopic and matched the actual operation. Screen-imaging guidance led to an accurate, smooth, minimally invasive and comparatively easy surgical procedure. Success rate of the model establishment evaluated by neurological function using the modified neurological score system was 74.07%. There was no significant difference in model establishment time, sensorimotor deficit and infarct volume percentage. Our findings indicate that the telescopic lens is effective in the screen surgical operation mode referred to as "long distance observation and short distance operation" and that screen-imaging guidance using an modified portable video macroscope can be utilized for the establishment of a middle cerebral artery occlusion model and micro-neurosurgery. PMID:25722675

  7. Screen-imaging guidance using a modified portable video macroscope for middle cerebral artery occlusion?

    PubMed Central

    Zhu, Xingbao; Luo, Junli; Liu, Yun; Chen, Guolong; Liu, Song; Ruan, Qiangjin; Deng, Xunding; Wang, Dianchun; Fan, Quanshui; Pan, Xinghua

    2012-01-01

    The use of operating microscopes is limited by the focal length. Surgeons using these instruments cannot simultaneously view and access the surgical field and must choose one or the other. The longer focal length (more than 1 000 mm) of an operating telescope permits a position away from the operating field, above the surgeon and out of the field of view. This gives the telescope an advantage over an operating microscope. We developed a telescopic system using screen-imaging guidance and a modified portable video macroscope constructed from a Computar MLH-10 × macro lens, a DFK-21AU04 USB CCD Camera and a Dell laptop computer as monitor screen. This system was used to establish a middle cerebral artery occlusion model in rats. Results showed that magnification of the modified portable video macroscope was appropriate (5–20 ×) even though the Computar MLH-10 × macro lens was placed 800 mm away from the operating field rather than at the specified working distance of 152.4 mm with a zoom of 1–40 ×. The screen-imaging telescopic technique was clear, life-like, stereoscopic and matched the actual operation. Screen-imaging guidance led to an accurate, smooth, minimally invasive and comparatively easy surgical procedure. Success rate of the model establishment evaluated by neurological function using the modified neurological score system was 74.07%. There was no significant difference in model establishment time, sensorimotor deficit and infarct volume percentage. Our findings indicate that the telescopic lens is effective in the screen surgical operation mode referred to as “long distance observation and short distance operation” and that screen-imaging guidance using an modified portable video macroscope can be utilized for the establishment of a middle cerebral artery occlusion model and micro-neurosurgery. PMID:25722675

  8. Image quality and dose efficiency of high energy phase sensitive x-ray imaging: phantom studies.

    PubMed

    Wong, Molly Donovan; Wu, Xizeng; Liu, Hong

    2014-01-01

    The goal of this preliminary study was to perform an image quality comparison of high energy phase sensitive imaging with low energy conventional imaging at similar radiation doses. The comparison was performed with the following phantoms: American College of Radiology (ACR), contrast-detail (CD), acrylic edge and tissue-equivalent. Visual comparison of the phantom images indicated comparable or improved image quality for all phantoms. Quantitative comparisons were performed through ACR and CD observer studies, both of which indicated higher image quality in the high energy phase sensitive images. The results of this study demonstrate the ability of high energy phase sensitive imaging to overcome existing challenges with the clinical implementation of phase contrast imaging and improve the image quality for a similar radiation dose as compared to conventional imaging near typical mammography energies. In addition, the results illustrate the capability of phase sensitive imaging to sustain the image quality improvement at high x-ray energies and for breast simulating phantoms, both of which indicate the potential to benefit fields such as mammography. Future studies will continue to investigate the potential for dose reduction and image quality improvement provided by high energy phase sensitive imaging. PMID:24865208

  9. Effect of image quality on calcification detection in digital mammography

    SciTech Connect

    Warren, Lucy M.; Mackenzie, Alistair; Cooke, Julie; Given-Wilson, Rosalind M.; Wallis, Matthew G.; Chakraborty, Dev P.; Dance, David R.; Bosmans, Hilde; Young, Kenneth C.

    2012-06-15

    Purpose: This study aims to investigate if microcalcification detection varies significantly when mammographic images are acquired using different image qualities, including: different detectors, dose levels, and different image processing algorithms. An additional aim was to determine how the standard European method of measuring image quality using threshold gold thickness measured with a CDMAM phantom and the associated limits in current EU guidelines relate to calcification detection. Methods: One hundred and sixty two normal breast images were acquired on an amorphous selenium direct digital (DR) system. Microcalcification clusters extracted from magnified images of slices of mastectomies were electronically inserted into half of the images. The calcification clusters had a subtle appearance. All images were adjusted using a validated mathematical method to simulate the appearance of images from a computed radiography (CR) imaging system at the same dose, from both systems at half this dose, and from the DR system at quarter this dose. The original 162 images were processed with both Hologic and Agfa (Musica-2) image processing. All other image qualities were processed with Agfa (Musica-2) image processing only. Seven experienced observers marked and rated any identified suspicious regions. Free response operating characteristic (FROC) and ROC analyses were performed on the data. The lesion sensitivity at a nonlesion localization fraction (NLF) of 0.1 was also calculated. Images of the CDMAM mammographic test phantom were acquired using the automatic setting on the DR system. These images were modified to the additional image qualities used in the observer study. The images were analyzed using automated software. In order to assess the relationship between threshold gold thickness and calcification detection a power law was fitted to the data. Results: There was a significant reduction in calcification detection using CR compared with DR: the alternative FROC (AFROC) area decreased from 0.84 to 0.63 and the ROC area decreased from 0.91 to 0.79 (p < 0.0001). This corresponded to a 30% drop in lesion sensitivity at a NLF equal to 0.1. Detection was also sensitive to the dose used. There was no significant difference in detection between the two image processing algorithms used (p > 0.05). It was additionally found that lower threshold gold thickness from CDMAM analysis implied better cluster detection. The measured threshold gold thickness passed the acceptable limit set in the EU standards for all image qualities except half dose CR. However, calcification detection varied significantly between image qualities. This suggests that the current EU guidelines may need revising. Conclusions: Microcalcification detection was found to be sensitive to detector and dose used. Standard measurements of image quality were a good predictor of microcalcification cluster detection.

  10. Indium-111 platelet imaging for detection of platelet deposition in abdominal aneurysms and prosthetic arterial grafts

    SciTech Connect

    Ritchie, J.L.; Stratton, J.R.; Thiele, B.; Haminton, G.W.; Warrick, L.N.; Huang, T.W.; Harker, L.A.

    1981-04-01

    Thirty-four platelet imaging studies were performed in 23 patients to determine whether platelet deposition could be detected in patients with vascular aneurysms (18 patients) or in patients in whom Dacron prosthetic grafts had been placed (5 patients). In patients in whom abnormal platelet deposition was detected, the effect of administration of platelet-active drugs on platelet deposition was examined. Of the 18 patients with an aneurysm, 12 had equivocally positive studies on initial imaging and 2 had equivocally positive images. Of five patients with Dacron arterial grafts in place, four had diffuse platelet deposition in the grafts; the fifth patient had a platelet deposition only in a pseudoaneurysm. Eight patients with an abdominal aneurysm and positive or equivocally positive baseline images were restudied during platelet-active drug therapy either with aspirin plus dipyridamole (seven patients) or with sulfinpyrazone (four patients). No patient studied during treatment with aspirin plus dipyridamole had detectably decreased platelet deposition compared with baseline determinations. In contrast, two of four patients studied while receiving sulfinpyrazone showed decreased platelet deposition. Thus, platelet imaging may be of value for studying platelet physiology in vivo and for assessing platelet-active drugs and the thrombogenicity of prosthetic graft materials in human beings.

  11. Dynamic flat panel detector versus image intensifier in cardiac imaging: dose and image quality

    NASA Astrophysics Data System (ADS)

    Vano, E.; Geiger, B.; Schreiner, A.; Back, C.; Beissel, J.

    2005-12-01

    The practical aspects of the dosimetric and imaging performance of a digital x-ray system for cardiology procedures were evaluated. The system was configured with an image intensifier (II) and later upgraded to a dynamic flat panel detector (FD). Entrance surface air kerma (ESAK) to phantoms of 16, 20, 24 and 28 cm of polymethyl methacrylate (PMMA) and the image quality of a test object were measured. Images were evaluated directly on the monitor and with numerical methods (noise and signal-to-noise ratio). Information contained in the DICOM header for dosimetry audit purposes was also tested. ESAK values per frame (or kerma rate) for the most commonly used cine and fluoroscopy modes for different PMMA thicknesses and for field sizes of 17 and 23 cm for II, and 20 and 25 cm for FD, produced similar results in the evaluated system with both technologies, ranging between 19 and 589 µGy/frame (cine) and 5 and 95 mGy min-1 (fluoroscopy). Image quality for these dose settings was better for the FD version. The 'study dosimetric report' is comprehensive, and its numerical content is sufficiently accurate. There is potential in the future to set those systems with dynamic FD to lower doses than are possible in the current II versions, especially for digital cine runs, or to benefit from improved image quality.

  12. Health-related quality of life among patients with peripheral arterial disease.

    PubMed

    Maksimovic, Milos; Vlajinac, Hristina; Marinkovic, Jelena; Kocev, Nikola; Voskresenski, Tatjana; Radak, Djordje

    2014-07-01

    We evaluated health-related quality of life (HRQoL) among patients with peripheral arterial disease (PAD) and compared the results with those of the general population. We also evaluated the possible association between some demographic and clinical characteristics of patients with PAD and HRQoL. A cross-sectional study involved 102 consecutive patients with verified PAD referred to the Dedinje Vascular Surgery Clinic in Belgrade. The HRQoL was measured using Medical Outcome Survey Short Form 36 (SF-36). Patients with PAD had significantly lower mean SF-36 scores for physical functioning, role-physical, bodily pain, social functioning, role-emotional, and mental health in comparison with the general population. The HRQoL was significantly more impaired in patients with severe PAD. Patients with PAD had a reduced HRQoL compared with the general population. The impact of PAD on HRQoL was independent of other factors related to both the disease and the HRQoL. PMID:23657177

  13. Imaging of vascular dynamics within the foot using dynamic diffuse optical tomography to diagnose peripheral arterial disease

    NASA Astrophysics Data System (ADS)

    Khalil, M. A.; Kim, H. K.; Hoi, J. W.; Kim, I.; Dayal, R.; Shrikande, G.; Hielscher, A. H.

    2013-03-01

    Peripheral Arterial Disease (PAD) is the narrowing of the functional area of the artery generally due to atherosclerosis. It affects between 8-12 million people in the United States and if untreated this can lead to ulceration, gangrene and ultimately amputation. The current diagnostic method for PAD is the ankle-brachial index (ABI). The ABI is a ratio of the patient's systolic blood pressure in the foot to that of the brachial artery in the arm, a ratio below 0.9 is indicative of affected vasculature. However, this method is ineffective in patients with calcified arteries (diabetic and end-stage renal failure patients), which falsely elevates the ABI recording resulting in a false negative reading. In this paper we present our results in a pilot study to deduce optical tomography's ability to detect poor blood perfusion in the foot. We performed an IRB approved 30 patient study, where we imaged the feet of the enrolled patients during a five stage dynamic imaging sequence. The patients were split up into three groups: 10 healthy subjects, 10 PAD patients and 10 PAD patients with diabetes and they were imaged while applying a pressure cuff to their thigh. Differences in the magnitude of blood pooling in the foot and rate at which the blood pools in the foot are all indicative of arterial disease.

  14. 4D motion modeling of the coronary arteries from CT images for robotic assisted minimally invasive surgery

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

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

  15. No-reference visual quality assessment for image inpainting

    NASA Astrophysics Data System (ADS)

    Voronin, V. V.; Frantc, V. A.; Marchuk, V. I.; Sherstobitov, A. I.; Egiazarian, K.

    2015-03-01

    Inpainting has received a lot of attention in recent years and quality assessment is an important task to evaluate different image reconstruction approaches. In many cases inpainting methods introduce a blur in sharp transitions in image and image contours in the recovery of large areas with missing pixels and often fail to recover curvy boundary edges. Quantitative metrics of inpainting results currently do not exist and researchers use human comparisons to evaluate their methodologies and techniques. Most objective quality assessment methods rely on a reference image, which is often not available in inpainting applications. Usually researchers use subjective quality assessment by human observers. It is difficult and time consuming procedure. This paper focuses on a machine learning approach for no-reference visual quality assessment for image inpainting based on the human visual property. Our method is based on observation that Local Binary Patterns well describe local structural information of the image. We use a support vector regression learned on assessed by human images to predict perceived quality of inpainted images. We demonstrate how our predicted quality value correlates with qualitative opinion in a human observer study. Results are shown on a human-scored dataset for different inpainting methods.

  16. Review of Source Images is Necessary for the Evaluation of Gadolinium-Enhanced MR Angiography for Renal Artery Stenosis

    SciTech Connect

    Wehrschuetz, M. Aschauer, M.; Portugaller, H.; Stix, A.; Wehrschuetz-Sigl, E.; Hausegger, K.; Ebner, F.

    2004-09-15

    The purpose of this study was to assess interobserver variability and accuracy in the evaluation of renal artery stenosis (RAS) with gadolinium-enhanced MR angiography (MRA) and digital subtraction angiography (DSA) in patients with hypertension. The authors found that source images are more accurate than maximum intensity projection (MIP) for depicting renal artery stenosis. Two independent radiologists reviewed MRA and DSA from 38 patients with hypertension. Studies were postprocessed to display images in MIP and source images. DSA was the standard for comparison in each patient. For each main renal artery, percentage stenosis was estimated for any stenosis detected by the two radiologists. To calculate sensitivity, specificity and accuracy, MRA studies and stenoses were categorized as normal, mild (1-39%), moderate (40-69%) or severe ({>=}70%), or occluded. DSA stenosis estimates of 70% or greater were considered hemodynamically significant. Analysis of variance demonstrated that MIP estimates of stenosis were greater than source image estimates for both readers. Differences in estimates for MIP versus DSA reached significance in one reader. The interobserver variance for MIP, source images and DSA was excellent (0.80< {kappa}{<=} 0.90). The specificity of source images was high (97%) but less for MIP (87%); average accuracy was 92% for MIP and 98% for source images. In this study, source images are significantly more accurate than MIP images in one reader with a similar trend was observed in the second reader. The interobserver variability was excellent. When renal artery stenosis is a consideration, high accuracy can only be obtained when source images are examined.

  17. Meat quality evaluation by hyperspectral imaging technique: an overview.

    PubMed

    Elmasry, Gamal; Barbin, Douglas F; Sun, Da-Wen; Allen, Paul

    2012-01-01

    During the last two decades, a number of methods have been developed to objectively measure meat quality attributes. Hyperspectral imaging technique as one of these methods has been regarded as a smart and promising analytical tool for analyses conducted in research and industries. Recently there has been a renewed interest in using hyperspectral imaging in quality evaluation of different food products. The main inducement for developing the hyperspectral imaging system is to integrate both spectroscopy and imaging techniques in one system to make direct identification of different components and their spatial distribution in the tested product. By combining spatial and spectral details together, hyperspectral imaging has proved to be a promising technology for objective meat quality evaluation. The literature presented in this paper clearly reveals that hyperspectral imaging approaches have a huge potential for gaining rapid information about the chemical structure and related physical properties of all types of meat. In addition to its ability for effectively quantifying and characterizing quality attributes of some important visual features of meat such as color, quality grade, marbling, maturity, and texture, it is able to measure multiple chemical constituents simultaneously without monotonous sample preparation. Although this technology has not yet been sufficiently exploited in meat process and quality assessment, its potential is promising. Developing a quality evaluation system based on hyperspectral imaging technology to assess the meat quality parameters and to ensure its authentication would bring economical benefits to the meat industry by increasing consumer confidence in the quality of the meat products. This paper provides a detailed overview of the recently developed approaches and latest research efforts exerted in hyperspectral imaging technology developed for evaluating the quality of different meat products and the possibility of its widespread deployment. PMID:22591341

  18. Univariant assessment of the visual quality of images

    NASA Astrophysics Data System (ADS)

    Jung, Mathieu; Leger, Dominique

    2000-06-01

    In order to evaluate the visual quality of images, most methods compare a degraded image to a perfect reference. We propose an original univariant (i.e. without reference) method based on the use of artificial neural networks. The principle is first to use a neural network to learn the quality of images taken from a pool of known examples, then use it to assess the quality of unknown images. The considered defects are compression artefacts, ringing or local singularities. To simplify, only images with defects that are not mixed with each other were first used. The method follows four steps. Observers are first required to mark degraded images to establish a pool of examples. Then, a characterization of the defect is extracted mathematically from the image. Then, the neural network learns how to establish a relation between the mathematical characterization of the defect and the visual mark. Finally, it can be used to assess the visual quality of an unknown image from the mathematical characterization of its defects. Two illustrative examples are presented: the assessment of the quality of JPEG compressed images and the detection of local defects.

  19. Image quality assessment by preprocessing and full reference model combination

    NASA Astrophysics Data System (ADS)

    Bianco, S.; Ciocca, G.; Marini, F.; Schettini, R.

    2009-01-01

    This paper focuses on full-reference image quality assessment and presents different computational strategies aimed to improve the robustness and accuracy of some well known and widely used state of the art models, namely the Structural Similarity approach (SSIM) by Wang and Bovik and the S-CIELAB spatial-color model by Zhang and Wandell. We investigate the hypothesis that combining error images with a visual attention model could allow a better fit of the psycho-visual data of the LIVE Image Quality assessment Database Release 2. We show that the proposed quality assessment metric better correlates with the experimental data.

  20. Advanced Imaging Tools Rather Than Hemodynamics Should Be the Primary Approach for Diagnosing, Following, and Managing Pulmonary Arterial Hypertension

    PubMed Central

    Gerges, Mario; Gerges, Christian; Lang, Irene M.

    2015-01-01

    Pulmonary hypertension (PH) is currently defined based on invasive measurements: a resting pulmonary artery pressure ? 25 mm Hg. For pulmonary arterial hypertension, a pulmonary arterial wedge pressure ? 15 mm Hg and pulmonary vascular resistance > 3 Wood units are also required. Thus, right heart catheterization is inevitable at present. However, the diagnosis, follow-up, and management of PH by noninvasive techniques is progressing. Significant advances have been achieved in the imaging of pulmonary vascular disease and the right ventricle. We review the current sensitivities and specificities of noninvasive imaging of PH and discuss its role and future potential to replace hemodynamics as the primary approach to screening, diagnosing, and following/managing PH. PMID:25840101

  1. Seeing Red: A new imaging technique produces video-quality images of red blood

    E-print Network

    Xie, Xiaoliang Sunney

    Seeing Red: A new imaging technique produces video-quality images of red blood cells in living Probes Cells A new nanowire laser could reveal new cellular mechanisms. TAGS IMAGING LASER IMAGING skin (shown) as well as red blood cells moving through the capillaries of live mice. Credit: Brian Saar

  2. Maximum likelihood difference scaling of image quality in compression-degraded images

    E-print Network

    Maloney, Laurence T.

    ] allow arbitrary compression of digital images. They are widely employed in encoding video [2Maximum likelihood difference scaling of image quality in compression-degraded images Christophe 24, 2007 (Doc. ID 86698); published October 1, 2007 Lossy image compression techniques allow

  3. Beamformed nearfield imaging of a simulated coronary artery containing a stenosis.

    PubMed

    Owsley, N L; Hull, A J

    1998-12-01

    This paper is concerned with the potential for the detection and location of an artery containing a partial blockage by exploiting the space-time properties of the shear wave field in the surrounding elastic soft tissue. As a demonstration of feasibility, an array of piezoelectric film vibration sensors is placed on the free surface of a urethane mold that contains a surgical tube. Inside the surgical tube is a nylon constriction that inhibits the water flowing through the tube. A turbulent field develops in and downstream from the blockage, creating a randomly fluctuating pressure on the inner wall of the tube. This force produces shear and compressional wave energy in the urethane. After the array is used to sample the dominant shear wave space-time energy field at low frequencies, a nearfield (i.e., focused) beamforming process then images the energy distribution in the three-dimensional solid. Experiments and numerical simulations are included to demonstrate the potential of this noninvasive procedure for the early identification of vascular blockages-the typical precursor of serious arterial disease in the human heart. PMID:10048847

  4. Arterial elasticity imaging: comparison of finite-element analysis models with high-resolution ultrasound speckle tracking

    PubMed Central

    2010-01-01

    Background The nonlinear mechanical properties of internal organs and tissues may be measured with unparalleled precision using ultrasound imaging with phase-sensitive speckle tracking. The many potential applications of this important noninvasive diagnostic approach include measurement of arterial stiffness, which is associated with numerous major disease processes. The accuracy of previous ultrasound measurements of arterial stiffness and vascular elasticity has been limited by the relatively low strain of nonlinear structures under normal physiologic pressure and the measurement assumption that the effect of the surrounding tissue modulus might be ignored in both physiologic and pressure equalized conditions. Methods This study performed high-resolution ultrasound imaging of the brachial artery in a healthy adult subject under normal physiologic pressure and the use of external pressure (pressure equalization) to increase strain. These ultrasound results were compared to measurements of arterial strain as determined by finite-element analysis models with and without a surrounding tissue, which was represented by homogenous material with fixed elastic modulus. Results Use of the pressure equalization technique during imaging resulted in average strain values of 26% and 18% at the top and sides, respectively, compared to 5% and 2%, at the top and sides, respectively, under physiologic pressure. In the artery model that included surrounding tissue, strain was 19% and 16% under pressure equalization versus 9% and 13% at the top and sides, respectively, under physiologic pressure. The model without surrounding tissue had slightly higher levels of strain under physiologic pressure compared to the other model, but the resulting strain values under pressure equalization were > 60% and did not correspond to experimental values. Conclusions Since pressure equalization may increase the dynamic range of strain imaging, the effect of the surrounding tissue on strain should be incorporated into models of arterial strain, particularly when the pressure equalization technique is used. PMID:20565833

  5. Feature maps driven no-reference image quality prediction of authentically distorted images

    NASA Astrophysics Data System (ADS)

    Ghadiyaram, Deepti; Bovik, Alan C.

    2015-03-01

    Current blind image quality prediction models rely on benchmark databases comprised of singly and synthetically distorted images, thereby learning image features that are only adequate to predict human perceived visual quality on such inauthentic distortions. However, real world images often contain complex mixtures of multiple distortions. Rather than a) discounting the effect of these mixtures of distortions on an image's perceptual quality and considering only the dominant distortion or b) using features that are only proven to be efficient for singly distorted images, we deeply study the natural scene statistics of authentically distorted images, in different color spaces and transform domains. We propose a feature-maps-driven statistical approach which avoids any latent assumptions about the type of distortion(s) contained in an image, and focuses instead on modeling the remarkable consistencies in the scene statistics of real world images in the absence of distortions. We design a deep belief network that takes model-based statistical image features derived from a very large database of authentically distorted images as input and discovers good feature representations by generalizing over different distortion types, mixtures, and severities, which are later used to learn a regressor for quality prediction. We demonstrate the remarkable competence of our features for improving automatic perceptual quality prediction on a benchmark database and on the newly designed LIVE Authentic Image Quality Challenge Database and show that our approach of combining robust statistical features and the deep belief network dramatically outperforms the state-of-the-art.

  6. Interplay between JPEG-2000 image coding and quality estimation

    NASA Astrophysics Data System (ADS)

    Pinto, Guilherme O.; Hemami, Sheila S.

    2013-03-01

    Image quality and utility estimators aspire to quantify the perceptual resemblance and the usefulness of a distorted image when compared to a reference natural image, respectively. Image-coders, such as JPEG-2000, traditionally aspire to allocate the available bits to maximize the perceptual resemblance of the compressed image when compared to a reference uncompressed natural image. Specifically, this can be accomplished by allocating the available bits to minimize the overall distortion, as computed by a given quality estimator. This paper applies five image quality and utility estimators, SSIM, VIF, MSE, NICE and GMSE, within a JPEG-2000 encoder for rate-distortion optimization to obtain new insights on how to improve JPEG-2000 image coding for quality and utility applications, as well as to improve the understanding about the quality and utility estimators used in this work. This work develops a rate-allocation algorithm for arbitrary quality and utility estimators within the Post- Compression Rate-Distortion Optimization (PCRD-opt) framework in JPEG-2000 image coding. Performance of the JPEG-2000 image coder when used with a variety of utility and quality estimators is then assessed. The estimators fall into two broad classes, magnitude-dependent (MSE, GMSE and NICE) and magnitudeindependent (SSIM and VIF). They further differ on their use of the low-frequency image content in computing their estimates. The impact of these computational differences is analyzed across a range of images and bit rates. In general, performance of the JPEG-2000 coder below 1.6 bits/pixel with any of these estimators is highly content dependent, with the most relevant content being the amount of texture in an image and whether the strongest gradients in an image correspond to the main contours of the scene. Above 1.6 bits/pixel, all estimators produce visually equivalent images. As a result, the MSE estimator provides the most consistent performance across all images, while specific estimators are expected to provide improved performance for images with suitable content.

  7. A quantitative method for visual phantom image quality evaluation

    NASA Astrophysics Data System (ADS)

    Chakraborty, Dev P.; Liu, Xiong; O'Shea, Michael; Toto, Lawrence C.

    2000-04-01

    This work presents an image quality evaluation technique for uniform-background target-object phantom images. The Degradation-Comparison-Threshold (DCT) method involves degrading the image quality of a target-containing region with a blocking processing and comparing the resulting image to a similarly degraded target-free region. The threshold degradation needed for 92% correct detection of the target region is the image quality measure of the target. Images of American College of Radiology (ACR) mammography accreditation program phantom were acquired under varying x-ray conditions on a digital mammography machine. Five observers performed ACR and DCT evaluations of the images. A figure-of-merit (FOM) of an evaluation method was defined which takes into account measurement noise and the change of the measure as a function of x-ray exposure to the phantom. The FOM of the DCT method was 4.1 times that of the ACR method for the specks, 2.7 times better for the fibers and 1.4 times better for the masses. For the specks, inter-reader correlations on the same image set increased significantly from 87% for the ACR method to 97% for the DCT method. The viewing time per target for the DCT method was 3 - 5 minutes. The observed greater sensitivity of the DCT method could lead to more precise Quality Control (QC) testing of digital images, which should improve the sensitivity of the QC process to genuine image quality variations. Another benefit of the method is that it can measure the image quality of high detectability target objects, which is impractical by existing methods.

  8. Intraoperative laser speckle contrast imaging improves the stability of rodent middle cerebral artery occlusion model

    NASA Astrophysics Data System (ADS)

    Yuan, Lu; Li, Yao; Li, Hangdao; Lu, Hongyang; Tong, Shanbao

    2015-09-01

    Rodent middle cerebral artery occlusion (MCAO) model is commonly used in stroke research. Creating a stable infarct volume has always been challenging for technicians due to the variances of animal anatomy and surgical operations. The depth of filament suture advancement strongly influences the infarct volume as well. We investigated the cerebral blood flow (CBF) changes in the affected cortex using laser speckle contrast imaging when advancing suture during MCAO surgery. The relative CBF drop area (CBF50, i.e., the percentage area with CBF less than 50% of the baseline) showed an increase from 20.9% to 69.1% when the insertion depth increased from 1.6 to 1.8 cm. Using the real-time CBF50 marker to guide suture insertion during the surgery, our animal experiments showed that intraoperative CBF-guided surgery could significantly improve the stability of MCAO with a more consistent infarct volume and less mortality.

  9. Intraoperative laser speckle contrast imaging improves the stability of rodent middle cerebral artery occlusion model.

    PubMed

    Yuan, Lu; Li, Yao; Li, Hangdao; Lu, Hongyang; Tong, Shanbao

    2015-09-01

    Rodent middle cerebral artery occlusion (MCAO) model is commonly used in stroke research. Creating a stable infarct volume has always been challenging for technicians due to the variances of animal anatomy and surgical operations. The depth of filament suture advancement strongly influences the infarct volume as well. We investigated the cerebral blood flow (CBF) changes in the affected cortex using laser speckle contrast imaging when advancing suture during MCAO surgery. The relative CBF drop area (CBF50, i.e., the percentage area with CBF less than 50% of the baseline) showed an increase from 20.9% to 69.1% when the insertion depth increased from 1.6 to 1.8 cm. Using the real-time CBF50 marker to guide suture insertion during the surgery, our animal experiments showed that intraoperative CBF-guided surgery could significantly improve the stability of MCAO with a more consistent infarct volume and less mortality. PMID:26359813

  10. Biomarker, Imaging and Quality of Life Studies Funding Program (BIQSFP)

    Cancer.gov

    Funded NCTN and NCORP Research Bases can apply for funding to support biomarker, imaging, and quality of life studies with or without Cost-Effectiveness Analysis (CEA) proposals associated with NCI network trials.

  11. Segmentation of the common carotid artery with active shape models from 3D ultrasound images

    NASA Astrophysics Data System (ADS)

    Yang, Xin; Jin, Jiaoying; He, Wanji; Yuchi, Ming; Ding, Mingyue

    2012-03-01

    Carotid atherosclerosis is a major cause of stroke, a leading cause of death and disability. In this paper, we develop and evaluate a new segmentation method for outlining both lumen and adventitia (inner and outer walls) of common carotid artery (CCA) from three-dimensional ultrasound (3D US) images for carotid atherosclerosis diagnosis and evaluation. The data set consists of sixty-eight, 17× 2× 2, 3D US volume data acquired from the left and right carotid arteries of seventeen patients (eight treated with 80mg atorvastain and nine with placebo), who had carotid stenosis of 60% or more, at baseline and after three months of treatment. We investigate the use of Active Shape Models (ASMs) to segment CCA inner and outer walls after statin therapy. The proposed method was evaluated with respect to expert manually outlined boundaries as a surrogate for ground truth. For the lumen and adventitia segmentations, respectively, the algorithm yielded Dice Similarity Coefficient (DSC) of 93.6%+/- 2.6%, 91.8%+/- 3.5%, mean absolute distances (MAD) of 0.28+/- 0.17mm and 0.34 +/- 0.19mm, maximum absolute distances (MAXD) of 0.87 +/- 0.37mm and 0.74 +/- 0.49mm. The proposed algorithm took 4.4 +/- 0.6min to segment a single 3D US images, compared to 11.7+/-1.2min for manual segmentation. Therefore, the method would promote the translation of carotid 3D US to clinical care for the fast, safety and economical monitoring of the atherosclerotic disease progression and regression during therapy.

  12. Segmentation of common carotid artery with active appearance models from ultrasound images

    NASA Astrophysics Data System (ADS)

    Yang, Xin; He, Wanji; Fenster, Aaron; Yuchi, Ming; Ding, Mingyue

    2013-02-01

    Carotid atherosclerosis is a major cause of stroke, a leading cause of death and disability. In this paper, a new segmentation method is proposed and evaluated for outlining the common carotid artery (CCA) from transverse view images, which were sliced from three-dimensional ultrasound (3D US) of 1mm inter-slice distance (ISD), to support the monitoring and assessment of carotid atherosclerosis. The data set consists of forty-eight 3D US images acquired from both left and right carotid arteries of twelve patients in two time points who had carotid stenosis of 60% or more at the baseline. The 3D US data were collected at baseline and three-month follow-up, where seven treated with 80mg atorvastatin and five with placebo. The baseline manual boundaries were used for Active Appearance Models (AAM) training; while the treatment data for segmentation testing and evaluation. The segmentation results were compared with experts manually outlined boundaries, as a surrogate for ground truth, for further evaluation. For the adventitia and lumen segmentations, the algorithm yielded Dice Coefficients (DC) of 92.06%+/-2.73% and 89.67%+/-3.66%, mean absolute distances (MAD) of 0.28+/-0.18 mm and 0.22+/-0.16 mm, maximum absolute distances (MAXD) of 0.71+/-0.28 mm and 0.59+/-0.21 mm, respectively. The segmentation results were also evaluated via Pratt's figure of merit (FOM) with the value of 0.61+/-0.06 and 0.66+/-0.05, which provides a quantitative measure for judging the similarity. Experimental results indicate that the proposed method can promote the carotid 3D US usage for a fast, safe and economical monitoring of the atherosclerotic disease progression and regression during therapy.

  13. Deriving the Intrahepatic Arteriovenous Shunt Rate from CT Images and Biochemical Data Instead of from Arterial Perfusion Scintigraphy in Hepatic Arterial Infusion Chemotherapy

    SciTech Connect

    Ozaki, Toshiro Seki, Hiroshi; Shiina, Makoto

    2009-09-15

    The purpose of the present study was to elucidate a method for predicting the intrahepatic arteriovenous shunt rate from computed tomography (CT) images and biochemical data, instead of from arterial perfusion scintigraphy, because adverse exacerbated systemic effects may be induced in cases where a high shunt rate exists. CT and arterial perfusion scintigraphy were performed in patients with liver metastases from gastric or colorectal cancer. Biochemical data and tumor marker levels of 33 enrolled patients were measured. The results were statistically verified by multiple regression analysis. The total metastatic hepatic tumor volume (V{sub metastasized}), residual hepatic parenchyma volume (V{sub residual}; calculated from CT images), and biochemical data were treated as independent variables; the intrahepatic arteriovenous (IHAV) shunt rate (calculated from scintigraphy) was treated as a dependent variable. The IHAV shunt rate was 15.1 {+-} 11.9%. Based on the correlation matrixes, the best correlation coefficient of 0.84 was established between the IHAV shunt rate and V{sub metastasized} (p < 0.01). In the multiple regression analysis with the IHAV shunt rate as the dependent variable, the coefficient of determination (R{sup 2}) was 0.75, which was significant at the 0.1% level with two significant independent variables (V{sub metastasized} and V{sub residual}). The standardized regression coefficients ({beta}) of V{sub metastasized} and V{sub residual} were significant at the 0.1 and 5% levels, respectively. Based on this result, we can obtain a predicted value of IHAV shunt rate (p < 0.001) using CT images. When a high shunt rate was predicted, beneficial and consistent clinical monitoring can be initiated in, for example, hepatic arterial infusion chemotherapy.

  14. Dosimetry and image quality assessment in a direct radiography system

    PubMed Central

    Oliveira, Bruno Beraldo; de Oliveira, Marcio Alves; Paixão, Lucas; Teixeira, Maria Helena Araújo; Nogueira, Maria do Socorro

    2014-01-01

    Objective To evaluate the mean glandular dose with a solid state detector and the image quality in a direct radiography system, utilizing phantoms. Materials and Methods Irradiations were performed with automatic exposure control and polymethyl methacrylate slabs with different thicknesses to calculate glandular dose values. The image quality was evaluated by means of the structures visualized on the images of the phantoms. Results Considering the uncertainty of the measurements, the mean glandular dose results are in agreement with the values provided by the equipment and with internationally adopted reference levels. Results obtained from images of the phantoms were in agreement with the reference values. Conclusion The present study contributes to verify the equipment conformity as regards dose values and image quality. PMID:25741119

  15. Adolescents with d-Transposition of the Great Arteries Corrected with the Arterial Switch Procedure: Neuropsychological Assessment and Structural Brain Imaging

    PubMed Central

    Bellinger, David C.; Wypij, David; Rivkin, Michael J.; DeMaso, David R.; Robertson, Richard L.; Dunbar-Masterson, Carolyn; Rappaport, Leonard A.; Wernovsky, Gil; Jonas, Richard A.; Newburger, Jane W.

    2011-01-01

    Background We report on neuropsychological and structural brain imaging assessments at age 16 years in children with d-transposition of the great arteries (d-TGA) who underwent the arterial switch operation (ASO) as infants. Children were randomly assigned to a vital organ support method, deep hypothermia with either total circulatory arrest or continuous low-flow cardiopulmonary bypass. Methods and Results Of 159 eligible adolescents, 139 (87%) participated. Academic achievement, memory, executive functions, visual-spatial skills, attention, and social cognition were assessed. Few significant treatment group differences were found. The occurrence of seizures in the post-operative period was the medical variable most consistently related to worse outcomes. The scores of both treatment groups tended to be lower than those of the test normative populations, with substantial proportions scoring 1 or more standard deviations below the expected mean. Although the test scores of most adolescents in this trial cohort are in the average range, a substantial proportion has received remedial academic or behavioral services (65%). MRI abnormalities were more frequent in the d-TGA group (33%) than in a referent group (4%). Conclusions Adolescents with d-TGA who have undergone the arterial switch operation are at increased neurodevelopmental risk. These data suggest that children with congenital heart disease may benefit from ongoing surveillance to identify emerging difficulties. Clinical Trial Registration NCT00000470, http://clinicaltrials.gov PMID:21875911

  16. Dyspnea, depression and health related quality of life in pulmonary arterial hypertension patients

    PubMed Central

    Talwar, Arunabh; Sahni, Sonu; Kim, Eun Ji; Verma, Sameer; Kohn, Nina

    2015-01-01

    Pulmonary arterial hypertension (PAH) is a rare and devastating disease which is characterized by worsening dyspnea and exercise tolerance. These patients are often found to have concomitant, depression, anxiety and impaired health-related quality of life (HRQOL). The interrelationship of dyspnea, depression and HRQOL in these patients is not well studied. Retrospective analysis was performed on 46 PAH patients (mean age 51.73). Patients completed Medical Outcomes Study Short - Form 36 V2 (SF-36) to measure HRQOL, Modified Medical Research Council (mMRC) Dyspnea Scale and Zung Depression Scale (ZDS). Physical Health Composite Scores (PCS) and Mental Health Composite Scores (MCS) were derived from SF-36. Spearman’s correlation was computed to determine degree of correlation between pairs of scales. 46 patients (12 males, 34 females; median age 51.4 yr) with confirmed PAH were considered for the study of which 36 patients (9 males, 27 females, median age 50.1 yr), were eligible for further analysis. MMRC Dyspnea Scale Score was 1.0 (Q1 to Q3:1.0 to 2.0). Median MCS was 52.1 (Q1 to Q3:41.7 to 57.1) and PCS was 37.9 (Q1 to Q3: 30.7 to 49.6). There was a significant negative correlation between dyspnea and PCS (r =?0.660, P<0.0001) and MCS (r =?0.342, P<0.0411). The ZDS was available for 17 of these patients; their median score was 42.0 (Q1 to Q3: 33.0 to 46.0). There was a significant correlation between the ZDS and PCS (r =?0.578, P<0.0150,) MCS (r =?0.752, P<0.0005). Patients with PAH suffer from diminished HRQOL correlating with their dyspnea and underlying depression. PMID:26535216

  17. Dyspnea, depression and health related quality of life in pulmonary arterial hypertension patients.

    PubMed

    Talwar, Arunabh; Sahni, Sonu; Kim, Eun Ji; Verma, Sameer; Kohn, Nina

    2015-10-01

    Pulmonary arterial hypertension (PAH) is a rare and devastating disease which is characterized by worsening dyspnea and exercise tolerance. These patients are often found to have concomitant, depression, anxiety and impaired health-related quality of life (HRQOL). The interrelationship of dyspnea, depression and HRQOL in these patients is not well studied. Retrospective analysis was performed on 46 PAH patients (mean age 51.73). Patients completed Medical Outcomes Study Short - Form 36 V2 (SF-36) to measure HRQOL, Modified Medical Research Council (mMRC) Dyspnea Scale and Zung Depression Scale (ZDS). Physical Health Composite Scores (PCS) and Mental Health Composite Scores (MCS) were derived from SF-36. Spearman's correlation was computed to determine degree of correlation between pairs of scales. 46 patients (12 males, 34 females; median age 51.4 yr) with confirmed PAH were considered for the study of which 36 patients (9 males, 27 females, median age 50.1 yr), were eligible for further analysis. MMRC Dyspnea Scale Score was 1.0 (Q1 to Q3:1.0 to 2.0). Median MCS was 52.1 (Q1 to Q3:41.7 to 57.1) and PCS was 37.9 (Q1 to Q3: 30.7 to 49.6). There was a significant negative correlation between dyspnea and PCS (r =-0.660, P<0.0001) and MCS (r =-0.342, P<0.0411). The ZDS was available for 17 of these patients; their median score was 42.0 (Q1 to Q3: 33.0 to 46.0). There was a significant correlation between the ZDS and PCS (r =-0.578, P<0.0150,) MCS (r =-0.752, P<0.0005). Patients with PAH suffer from diminished HRQOL correlating with their dyspnea and underlying depression. PMID:26535216

  18. RADARSAT-1 Image Quality - Continuing Success in Extended Mission

    NASA Astrophysics Data System (ADS)

    Srivastava, S. K.; Le Dantec, P.; Banik, B. T.; Guertin, G.; Gray, R.; Hawkins, R. K.; Murnaghan, K.

    2003-03-01

    RADARSAT-1, the first Canadian SAR remote sensing satellite, was launched on November 4, 1995. After commissioning, it was put in to routine operations on April 1, 1996. Since then, it has been operating successfully, even after completing its five and a quarter years of design lifetime, and providing data to users for their intended applications. Significant effort continues to be expended in the provision of high quality products to users generated by the Canadian Data Processing Facility (CDPF). After initial calibration, both single beams and ScanSAR are monitored routinely as part of the Maintenance Phase for image quality performance. Image quality is monitored through periodic measurements of impulse response function, location error and radiometry, using images of the Amazon Rainforest and RADARSAT-1 Precision Transponders (RPTs). ScanSAR radiometry is also monitored through periodic measurements of the Amazon Rainforest. A major upgrade of the ScanSAR processor completed recently in CDPF made significant improvements in image quality and radiometry. Measured results indicate that image quality is better than system specification and maintained. This paper will describe the overall process of data acquisition, data analysis and re- calibration for image quality maintenance.

  19. Objective image quality assessment based on support vector regression.

    PubMed

    Narwaria, Manish; Lin, Weisi

    2010-03-01

    Objective image quality estimation is useful in many visual processing systems, and is difficult to perform in line with the human perception. The challenge lies in formulating effective features and fusing them into a single number to predict the quality score. In this brief, we propose a new approach to address the problem, with the use of singular vectors out of singular value decomposition (SVD) as features for quantifying major structural information in images and then support vector regression (SVR) for automatic prediction of image quality. The feature selection with singular vectors is novel and general for gauging structural changes in images as a good representative of visual quality variations. The use of SVR exploits the advantages of machine learning with the ability to learn complex data patterns for an effective and generalized mapping of features into a desired score, in contrast with the oft-utilized feature pooling process in the existing image quality estimators; this is to overcome the difficulty of model parameter determination for such a system to emulate the related, complex human visual system (HVS) characteristics. Experiments conducted with three independent databases confirm the effectiveness of the proposed system in predicting image quality with better alignment with the HVS's perception than the relevant existing work. The tests with untrained distortions and databases further demonstrate the robustness of the system and the importance of the feature selection. PMID:20100674

  20. Imaging quality full chip verification for yield improvement

    NASA Astrophysics Data System (ADS)

    Yang, Qing; Zhou, CongShu; Quek, ShyueFong; Lu, Mark; Foong, YeeMei; Qiu, JianHong; Pandey, Taksh; Dover, Russell

    2013-04-01

    Basic image intensity parameters, like maximum and minimum intensity values (Imin and Imax), image logarithm slope (ILS), normalized image logarithm slope (NILS) and mask error enhancement factor (MEEF) , are well known as indexes of photolithography imaging quality. For full chip verification, hotspot detection is typically based on threshold values for line pinching or bridging. For image intensity parameters it is generally harder to quantify an absolute value to define where the process limit will occur, and at which process stage; lithography, etch or post- CMP. However it is easy to conclude that hot spots captured by image intensity parameters are more susceptible to process variation and very likely to impact yield. In addition these image intensity hot spots can be missed by using resist model verification because the resist model normally is calibrated by the wafer data on a single resist plane and is an empirical model which is trying to fit the resist critical dimension by some mathematic algorithm with combining optical calculation. Also at resolution enhancement technology (RET) development stage, full chip imaging quality check is also a method to qualify RET solution, like Optical Proximity Correct (OPC) performance. To add full chip verification using image intensity parameters is also not as costly as adding one more resist model simulation. From a foundry yield improvement and cost saving perspective, it is valuable to quantify the imaging quality to find design hot spots to correctly define the inline process control margin. This paper studies the correlation between image intensity parameters and process weakness or catastrophic hard failures at different process stages. It also demonstrated how OPC solution can improve full chip image intensity parameters. Rigorous 3D resist profile simulation across the full height of the resist stack was also performed to identify a correlation to the image intensity parameter. A methodology of post-OPC full chip verification is proposed for improving OPC quality at RET development stage and for inline process control and yield improvement at production stage.

  1. Noise Reduction in CMOS Image Sensors for High Quality Imaging: The Autocorrelation Function Filter on Burst Image Sequences

    E-print Network

    Nielsen, Frank

    : Source and classification of the two types of noise in a CMOS image sensor. The `W' and `C' attributesNoise Reduction in CMOS Image Sensors for High Quality Imaging: The Autocorrelation Function Filter-hiro@waseda.jp Abstract We propose a new method for image noise detection and reduction in complementary metal oxide semi

  2. Cardiac rehabilitation may not provide a quality of life benefit in coronary artery disease patients

    PubMed Central

    2012-01-01

    Background Improvements in patient-reported health-related quality of life (HRQoL) are important goals of cardiac rehabilitation (CR). In patients undergoing coronary angiography for angina and with documented coronary artery disease (CAD), the present study compared HRQoL over 6 months in CR participants and non-participants. Clinical predictors of CR participants were also assessed. Methods A total of 221 consecutive patients undergoing angiography for angina with documented CAD and who were eligible for a CR program were recruited. CR participants were enrolled in a six-week Phase II outpatient CR course (31%, n?=?68) within 2 months following angiography and the non-participants were included as a control. At baseline (angiography), one and six months post angiography, clinical and HRQoL data were obtained including the Short Form-36 (SF-36) and the Seattle Angina Questionnaire (SAQ). The response rate for the HRQoL assessment was 68% (n?=?150). Cross sectional comparisons were age-adjusted and performed using logistic or linear regression as appropriate. Longitudinal changes in HRQoL were assessed using least squares regression. Finally, a multiple logistic regression was fitted with CR participant as the final outcome. Results At angiography, the CR non-participants were older, and age-adjusted analyses revealed poorer physical (angina limitation: 54?±?25 versus 64?±?22, p <0.05) and mental HRQoL (significant psycho-social distress: 62%, n?=?95 versus 47%, n?=?32, p <0.05) compared to the CR participants. In addition, the CR participants were more likely to have undergone angiography for myocardial infarction (OR?=?2.8, 95% CI 1.5-5.3, p?=?0.001). By six months, all patients showed an improvement in HRQoL indices, however the rate of improvement did not differ between the controls and CR participants. Conclusion Following angiography, CAD patients reported improvements in both generic and disease-specific HRQoL, however CR participation did not influence this outcome. This may be explained by biases in CR enrollment, whereby acute patients, who may be less limited in HRQoL compared to stable, chronic patients, are targeted for CR participation. Further investigation is required so CR programs maximize the quality of life benefits to all potential CR patients. PMID:23164456

  3. IEEE TRANSACTIONS ON MEDICAL IMAGING ---FINAL MANUSCRIPT 20040117 1 Interactive Virtual Endoscopy in Coronary Arteries

    E-print Network

    Wahle, Andreas

    in Coronary Arteries based on Multi­Modality Fusion Andreas Wahle, # Senior Member, IEEE, Mark E. Olszewski­independent virtual endoscopy in human coronary arteries is presented in this pa­ per. It incorporates previously results in a three­ or four­dimensional (3­D/4­D) model of a coronary artery, specifically of its lumen

  4. High Speed Terahertz Pulse Imaging in the Reflection Geometry and Image Quality Enhancement by Digital Image Processing

    NASA Astrophysics Data System (ADS)

    Shon, Chae-Hwa; Chong, Won-Yong; Jeon, Seok-Gy; Kim, Geun-Ju; Kim, Jung-Il; Jin, Yun-Sik

    2008-01-01

    We describe the formation and enhancement of two dimensional pulsed terahertz (THz) images obtained in the reflection geometry with a high-speed optical delay line. Two test objects are imaged and analyzed with respect to material information and concealed structure. Clear THz images were obtained with various imaging modes and were compared with the X-ray images. The THz image of a sample revealed material features that the X-ray image cannot distinguish. We could enhance the THz image quality using various image processing techniques, such as edge detection, de-noising, high-pass filtering, and wavelet filtering.

  5. Raman chemical imaging technology for food safety and quality evaluation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Raman chemical imaging combines Raman spectroscopy and digital imaging to visualize composition and morphology of a target. This technique offers great potential for food safety and quality research. Most commercial Raman instruments perform measurement at microscopic level, and the spatial range ca...

  6. SUBJECTIVE IMAGE QUALITY TRADEOFFS BETWEEN SPATIAL RESOLUTION AND QUANTIZATION NOISE

    E-print Network

    Pappas, Thrasyvoulos N.

    SUBJECTIVE IMAGE QUALITY TRADEOFFS BETWEEN SPATIAL RESOLUTION AND QUANTIZATION NOISE Soo Hyun Bae, Thrasyvoulos N. Pappas , Biing-Hwang Juang Center for Signal and Image Processing, Georgia Institute- tization noise has been examined in our previous work. Subjec- tive experiments indicate

  7. Micro-CT image-derived metrics quantify arterial wall distensibility reduction in a rat model of pulmonary hypertension

    NASA Astrophysics Data System (ADS)

    Johnson, Roger H.; Karau, Kelly L.; Molthen, Robert C.; Haworth, Steven T.; Dawson, Christopher A.

    2000-04-01

    We developed methods to quantify arterial structural and mechanical properties in excised rat lungs and applied them to investigate the distensibility decrease accompanying chronic hypoxia-induced pulmonary hypertension. Lungs of control and hypertensive (three weeks 11% O2) animals were excised and a contrast agent introduced before micro-CT imaging with a special purpose scanner. For each lung, four 3D image data sets were obtained, each at a different intra-arterial contrast agent pressure. Vessel segment diameters and lengths were measured at all levels in the arterial tree hierarchy, and these data used to generate features sensitive to distensibility changes. Results indicate that measurements obtained from 3D micro-CT images can be used to quantify vessel biomechanical properties in this rat model of pulmonary hypertension and that distensibility is reduced by exposure to chronic hypoxia. Mechanical properties can be assessed in a localized fashion and quantified in a spatially-resolved way or as a single parameter describing the tree as a whole. Micro-CT is a nondestructive way to rapidly assess structural and mechanical properties of arteries in small animal organs maintained in a physiological state. Quantitative features measured by this method may provide valuable insights into the mechanisms causing the elevated pressures in pulmonary hypertension of differing etiologies and should become increasingly valuable tools in the study of complex phenotypes in small-animal models of important diseases such as hypertension.

  8. A feature-enriched completely blind image quality evaluator.

    PubMed

    Lin Zhang; Lei Zhang; Bovik, Alan C

    2015-08-01

    Existing blind image quality assessment (BIQA) methods are mostly opinion-aware. They learn regression models from training images with associated human subjective scores to predict the perceptual quality of test images. Such opinion-aware methods, however, require a large amount of training samples with associated human subjective scores and of a variety of distortion types. The BIQA models learned by opinion-aware methods often have weak generalization capability, hereby limiting their usability in practice. By comparison, opinion-unaware methods do not need human subjective scores for training, and thus have greater potential for good generalization capability. Unfortunately, thus far no opinion-unaware BIQA method has shown consistently better quality prediction accuracy than the opinion-aware methods. Here, we aim to develop an opinion-unaware BIQA method that can compete with, and perhaps outperform, the existing opinion-aware methods. By integrating the features of natural image statistics derived from multiple cues, we learn a multivariate Gaussian model of image patches from a collection of pristine natural images. Using the learned multivariate Gaussian model, a Bhattacharyya-like distance is used to measure the quality of each image patch, and then an overall quality score is obtained by average pooling. The proposed BIQA method does not need any distorted sample images nor subjective quality scores for training, yet extensive experiments demonstrate its superior quality-prediction performance to the state-of-the-art opinion-aware BIQA methods. The MATLAB source code of our algorithm is publicly available at www.comp.polyu.edu.hk/~cslzhang/IQA/ILNIQE/ILNIQE.htm. PMID:25915960

  9. A patient image-based technique to assess the image quality of clinical chest radiographs

    NASA Astrophysics Data System (ADS)

    Lin, Yuan; Samei, Ehsan; Luo, Hui; Dobbins, James T., III; McAdams, H. Page; Wang, Xiaohui; Sehnert, William J.; Barski, Lori; Foos, David H.

    2011-03-01

    Current clinical image quality assessment techniques mainly analyze image quality for the imaging system in terms of factors such as the capture system DQE and MTF, the exposure technique, and the particular image processing method and processing parameters. However, when assessing a clinical image, radiologists seldom refer to these factors, but rather examine several specific regions of the image to see whether the image is suitable for diagnosis. In this work, we developed a new strategy to learn and simulate radiologists' evaluation process on actual clinical chest images. Based on this strategy, a preliminary study was conducted on 254 digital chest radiographs (38 AP without grids, 35 AP with 6:1 ratio grids and 151 PA with 10:1 ratio grids). First, ten regional based perceptual qualities were summarized through an observer study. Each quality was characterized in terms of a physical quantity measured from the image, and as a first step, the three physical quantities in lung region were then implemented algorithmically. A pilot observer study was performed to verify the correlation between image perceptual qualities and physical quantitative qualities. The results demonstrated that our regional based metrics have promising performance for grading perceptual properties of chest radiographs.

  10. Impact of age on improvement in health-related quality of life 5 years after coronary artery bypass grafting.

    PubMed

    Herlitz, J; Wiklund, I; Sjöland, H; Karlson, B W; Karlsson, T; Haglid, M; Hartford, M; Caidahl, K

    2000-03-01

    The aim of this study was to describe the relief of symptoms and improvement in other aspects of health-related quality of life 5 years after coronary artery by-pass grafting in relation to age. Patients in western Sweden were approached with an inquiry prior to surgery and 5 years after the operation. Health-related quality of life was estimated with 3 different instruments: Physical Activity Score (PAS), Nottingham Health Profile (NHP), Psychological General Well-Being Index (PGWB). Prior to surgery patients were approached either in the ward or by post and 5 years after surgery they were approached by post. A total of 1719 patients were available for the survey, of whom 876 (51%) responded to the survey both prior to and after 5 years. Among the 876 respondents 287 were <60 years, 331 were 60-67 years and 258 were >67 years. In terms of physical activity, chest pain and dyspnoea, a similar improvement was observed regardless of age. In terms of health-related quality of life questionnaires, there was an inverse association between age and improvement when using PAS and a similar trend was observed with NHP and PGWB. In conclusion, 5 years after coronary artery bypass grafting relief of symptoms and improvement in physical activity was not associated with age, whereas improvement in other aspects of health-related quality of life tended to be less marked in elderly people. Overall age seemed to have a small impact on the improved well-being 5 years after coronary surgery. However, due to the limited response rate the results may not be applicable to a non-selected coronary artery bypass grafting population. PMID:10782941

  11. Perceived quality of wood images influenced by the skewness of image histogram

    NASA Astrophysics Data System (ADS)

    Katsura, Shigehito; Mizokami, Yoko; Yaguchi, Hirohisa

    2015-08-01

    The shape of image luminance histograms is related to material perception. We investigated how the luminance histogram contributed to improvements in the perceived quality of wood images by examining various natural wood and adhesive vinyl sheets with printed wood grain. In the first experiment, we visually evaluated the perceived quality of wood samples. In addition, we measured the colorimetric parameters of the wood samples and calculated statistics of image luminance. The relationship between visual evaluation scores and image statistics suggested that skewness and kurtosis affected the perceived quality of wood. In the second experiment, we evaluated the perceived quality of wood images with altered luminance skewness and kurtosis using a paired comparison method. Our result suggests that wood images are more realistic if the skewness of the luminance histogram is slightly negative.

  12. Digital image quality measurements by objective and subjective methods from series of parametrically degraded images

    NASA Astrophysics Data System (ADS)

    Tachó, Aura; Mitjà, Carles; Martínez, Bea; Escofet, Jaume; Ralló, Miquel

    2013-11-01

    Many digital image applications like digitization of cultural heritage for preservation purposes operate with compressed files in one or more image observing steps. For this kind of applications JPEG compression is one of the most widely used. Compression level, final file size and quality loss are parameters that must be managed optimally. Although this loss can be monitored by means of objective image quality measurements, the real challenge is to know how it can be related with the perceived image quality by observers. A pictorial image has been degraded by two different procedures. The first, applying different levels of low pass filtering by convolving the image with progressively broad Gauss kernels. The second, saving the original file to a series of JPEG compression levels. In both cases, the objective image quality measurement is done by analysis of the image power spectrum. In order to obtain a measure of the perceived image quality, both series of degraded images are displayed on a computer screen organized in random pairs. The observers are compelled to choose the best image of each pair. Finally, a ranking is established applying Thurstone scaling method. Results obtained by both measurements are compared between them and with other objective measurement method as the Slanted Edge Test.

  13. Intravascular near-infrared fluorescence molecular imaging of atherosclerosis: toward coronary arterial visualization of biologically high-risk plaques

    NASA Astrophysics Data System (ADS)

    Calfon, Marcella A.; Vinegoni, Claudio; Ntziachristos, Vasilis; Jaffer, Farouc A.

    2010-01-01

    New imaging methods are urgently needed to identify high-risk atherosclerotic lesions prior to the onset of myocardial infarction, stroke, and ischemic limbs. Molecular imaging offers a new approach to visualize key biological features that characterize high-risk plaques associated with cardiovascular events. While substantial progress has been realized in clinical molecular imaging of plaques in larger arterial vessels (carotid, aorta, iliac), there remains a compelling, unmet need to develop molecular imaging strategies targeted to high-risk plaques in human coronary arteries. We present recent developments in intravascular near-IR fluorescence catheter-based strategies for in vivo detection of plaque inflammation in coronary-sized arteries. In particular, the biological, light transmission, imaging agent, and engineering principles that underlie a new intravascular near-IR fluorescence sensing method are discussed. Intravascular near-IR fluorescence catheters appear highly translatable to the cardiac catheterization laboratory, and thus may offer a new in vivo method to detect high-risk coronary plaques and to assess novel atherosclerosis biologics.

  14. Optimization and image quality assessment of the alpha-image reconstruction algorithm: iterative reconstruction with well-defined image quality metrics

    NASA Astrophysics Data System (ADS)

    Lebedev, Sergej; Sawall, Stefan; Kuchenbecker, Stefan; Faby, Sebastian; Knaup, Michael; Kachelrieß, Marc

    2015-03-01

    The reconstruction of CT images with low noise and highest spatial resolution is a challenging task. Usually, a trade-off between at least these two demands has to be found or several reconstructions with mutually exclusive properties, i.e. either low noise or high spatial resolution, have to be performed. Iterative reconstruction methods might be suitable tools to overcome these limitations and provide images of highest diagnostic quality with formerly mutually exclusive image properties. While image quality metrics like the modulation transfer function (MTF) or the point spread function (PSF) are well-defined in case of standard reconstructions, e.g. filtered backprojection, the iterative algorithms lack these metrics. To overcome this issue alternate methodologies like the model observers have been proposed recently to allow a quantification of a usually task-dependent image quality metric.1 As an alternative we recently proposed an iterative reconstruction method, the alpha-image reconstruction (AIR), providing well-defined image quality metrics on a per-voxel basis.2 In particular, the AIR algorithm seeks to find weighting images, the alpha-images, that are used to blend between basis images with mutually exclusive image properties. The result is an image with highest diagnostic quality that provides a high spatial resolution and a low noise level. As the estimation of the alpha-images is computationally demanding we herein aim at optimizing this process and highlight the favorable properties of AIR using patient measurements.

  15. A review of ultrasound common carotid artery image and video segmentation techniques.

    PubMed

    Loizou, Christos P

    2014-12-01

    The determination of the wall thickness [intima-media thickness (IMT)], the delineation of the atherosclerotic carotid plaque, the measurement of the diameter in the common carotid artery (CCA), as well as the grading of its stenosis are important for the evaluation of the atherosclerosis disease. All these measurements are also considered to be significant markers for the clinical evaluation of the risk of stroke. A number of CCA segmentation techniques have been proposed in the last few years either for the segmentation of the intima-media complex (IMC), the lumen of the CCA, or for the atherosclerotic carotid plaque from ultrasound images or videos of the CCA. The present review study proposes and discusses the methods and systems introduced so far in the literature for performing automated or semi-automated segmentation in ultrasound images or videos of the CCA. These are based on edge detection, active contours, level sets, dynamic programming, local statistics, Hough transform, statistical modeling, neural networks, and an integration of the above methods. Furthermore, the performance of these systems is evaluated and discussed based on various evaluation metrics. We finally propose the best performing method that can be used for the segmentation of the IMC and the atherosclerotic carotid plaque in ultrasound images and videos. We end the present review study with a discussion of the different image and video CCA segmentation techniques, future perspectives, and further extension of these techniques to ultrasound video segmentation and wall tracking of the CCA. Future work on the segmentation of the CCA will be focused on the development of integrated segmentation systems for the complete segmentation of the CCA as well as the segmentation and motion analysis of the plaque and or the IMC from ultrasound video sequences of the CCA. These systems will improve the evaluation, follow up, and treatment of patients affected by advanced atherosclerosis disease conditions. PMID:25284219

  16. Effect of optical aberrations on image quality and visual performance

    NASA Astrophysics Data System (ADS)

    Ravikumar, Sowmya

    In addition to the effects of diffraction, retinal image quality in the human eye is degraded by optical aberrations. Although the paraxial geometric optics description of defocus consists of a simple blurred circle whose size determines the extent of blur, in reality the interactions between monochromatic and chromatic aberrations create a complex pattern of retinal image degradation. My thesis work hypothesizes that although both monochromatic and chromatic optical aberrations in general reduce image quality from best achievable, the underlying causes of retinal image quality degradation are characteristic of the nature of the aberration, its interactions with other aberrations as well as the composition of the stimulus. To establish a controlled methodology, a computational model of the retinal image with various levels of aberrations was used to create filters equivalent to those produced by real optical aberrations. Visual performance was measured psychophysically by using these special filters that separately modulated amplitude and phase in the retinal image. In order to include chromatic aberration into the optical interactions, a computational polychromatic model of the eye was created and validated. The model starts with monochromatic wavefront maps and derives a composite white light point-spread function whose quality was assessed using metrics of image quality. Finally, in order to assess the effectiveness of simultaneous multifocal intra-ocular lenses in correcting the eye's optical aberrations, a polychromatic computational model of a pseudophakic eye was constructed. This model incorporated the special chromatic properties unique to an eye corrected with hybrid refractive-diffractive optical elements. Results showed that normal optical aberrations reduced visual performance not only by reducing image contrast but also by altering the phase structure of the image. Longitudinal chromatic aberration had a greater effect on image quality in isolation than in the presence of monochromatic aberrations. Also, the diffractive optical element was found to improve polychromatic image quality in a pseudophakic eye by chromatic correction. My thesis work shows that in order to obtain maximal improvement in image quality, it is important to correct both monochromatic and chromatic aberrations.

  17. Automatic quality assessment in structural brain magnetic resonance imaging

    PubMed Central

    Mortamet, Bénédicte; Bernstein, Matt A.; Jack, Clifford R.; Gunter, Jeffrey L.; Ward, Chadwick; Britson, Paula J.; Meuli, Reto; Thiran, Jean-Philippe; Krueger, Gunnar

    2009-01-01

    MRI has evolved into an important diagnostic technique in medical imaging. However, reliability of the derived diagnosis can be degraded by artifacts, which challenge both radiologists and automatic computer-aided diagnosis. This paper proposes a fully automatic method for measuring image quality of 3D structural MRI. Quality measures are derived by analyzing the air background of magnitude images and are capable of detecting image degradation from several sources, including bulk motion, residual magnetization from incomplete spoiling, blurring, ghosting, etc. The method has been validated on 749 3D T1-weighted 1.5 T and 3 T head scans acquired at 36 Alzheimer's Disease Neuroimaging Initiative (ADNI) study sites operating with various software and hardware combinations. Results are compared against qualitative grades assigned by the ADNI quality control center (taken as the reference standard). The derived quality indices are independent of the MRI system used and agree with the reference standard quality ratings with high sensitivity and specificity (>85%). The proposed procedures for quality assessment could be of great value for both research and routine clinical imaging. It could greatly improve workflow through its ability to rule-out the need for a repeat scan while the patient is still in the magnet bore. PMID:19526493

  18. Stent implantation and optical frequency domain imaging with carbon dioxide for chronic total occlusion in the superficial femoral artery.

    PubMed

    Nakamura, Akihiro; Noda, Kazuki; Nakajima, Sota; Endo, Hideaki; Takahashi, Tohru; Nozaki, Eiji

    2015-10-01

    A 68-year-old female was presented with claudication in the left lower leg. She underwent angiography with carbon dioxide (CO2) because she had a history of anaphylactic shock to iodinated contrast medium. It revealed total occlusion of the left superficial femoral artery (SFA), and subsequently endovascular therapy (EVT) was performed by an antegrade approach from the left common femoral artery. After stent implantation, we performed optical frequency domain imaging (OFDI) using CO2 as contrast medium. OFDI has been extensively studied in the coronary circulation; however, its use in the peripheral arterial circulation is scarce. We present a case of stent implantation and OFDI using CO2 as an ancillary tool during EVT for SFA lesions in the patient with contraindication to iodinated contrast medium. PMID:25319810

  19. Comparison of Intravoxel Incoherent Motion Diffusion-Weighted MR Imaging and Arterial Spin Labeling MR Imaging in Gliomas

    PubMed Central

    Zhang, Zhiqiang; Zhou, Zhenyu; Zhang, Zhongping; Zhang, Yong; Zhang, Zongjun

    2015-01-01

    Gliomas grading is important for treatment plan; we aimed to investigate the application of intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) in gliomas grading, by comparing with the three-dimensional pseudocontinuous arterial spin labeling (3D pCASL). 24 patients (13 high grade gliomas and 11 low grade gliomas) underwent IVIM DWI and 3D pCASL imaging before operation; maps of fast diffusion coefficient (D?), slow diffusion coefficient (D), fractional perfusion-related volume (f), and apparent diffusion coefficient (ADC) as well as cerebral blood flow (CBF) were calculated and then coregistered to generate the corresponding parameter values. We found CBF and D? were higher in the high grade gliomas, whereas ADC, D, and f were lower (all P < 0.05). In differentiating the high from low grade gliomas, the maximum areas under the curves (AUC) of D?, CBF, and ADC were 0.857, 0.85, and 0.902, respectively. CBF was negatively correlated with f in tumor (r = ?0.619, P = 0.001). ADC was positively correlated with D in both tumor and white matter (r = 0.887, P = 0.000 and r = 0.824, P = 0.000, resp.). There was no correlation between CBF and D? in both tumor and white matter (P > 0.05). IVIM DWI showed more efficiency than 3D pCASL but less validity than conventional DWI in differentiating the high from low grade gliomas. PMID:25945328

  20. Image quality improvement of polygon computer generated holography.

    PubMed

    Pang, Xiao-Ning; Chen, Ding-Chen; Ding, Yi-Cong; Chen, Yi-Gui; Jiang, Shao-Ji; Dong, Jian-Wen

    2015-07-27

    Quality of holographic reconstruction image is seriously affected by undesirable messy fringes in polygon-based computer generated holography. Here, several methods have been proposed to improve the image quality, including a modified encoding method based on spatial-domain Fraunhofer diffraction and a specific LED light source. Fast Fourier transform is applied to the basic element of polygon and fringe-invisible reconstruction is achieved after introducing initial random phase. Furthermore, we find that the image with satisfactory fidelity and sharp edge can be reconstructed by either a LED with moderate coherence level or a modulator with small pixel pitch. Satisfactory image quality without obvious speckle noise is observed under the illumination of bandpass-filter-aided LED. The experimental results are consistent well with the correlation analysis on the acceptable viewing angle and the coherence length of the light source. PMID:26367569

  1. Magnetic Resonance Imaging (MRI) Analysis of Fibroid Location in Women Achieving Pregnancy After Uterine Artery Embolization

    SciTech Connect

    Walker, Woodruff J.; Bratby, Mark John

    2007-09-15

    The purpose of this study was to evaluate the fibroid morphology in a cohort of women achieving pregnancy following treatment with uterine artery embolization (UAE) for symptomatic uterine fibroids. A retrospective review of magnetic resonance imaging (MRI) of the uterus was performed to assess pre-embolization fibroid morphology. Data were collected on fibroid size, type, and number and included analysis of follow-up imaging to assess response. There have been 67 pregnancies in 51 women, with 40 live births. Intramural fibroids were seen in 62.7% of the women (32/48). Of these the fibroids were multiple in 16. A further 12 women had submucosal fibroids, with equal numbers of types 1 and 2. Two of these women had coexistent intramural fibroids. In six women the fibroids could not be individually delineated and formed a complex mass. All subtypes of fibroid were represented in those subgroups of women achieving a live birth versus those who did not. These results demonstrate that the location of uterine fibroids did not adversely affect subsequent pregnancy in the patient population investigated. Although this is only a small qualitative study, it does suggest that all types of fibroids treated with UAE have the potential for future fertility.

  2. Coronary arteries motion modeling on 2D x-ray images

    NASA Astrophysics Data System (ADS)

    Gao, Yang; Sundar, Hari

    2012-02-01

    During interventional procedures, 3D imaging modalities like CT and MRI are not commonly used due to interference with the surgery and radiation exposure concerns. Therefore, real-time information is usually limited and building models of cardiac motion are difficult. In such case, vessel motion modeling based on 2-D angiography images become indispensable. Due to issues with existing vessel segmentation algorithms and the lack of contrast in occluded vessels, manual segmentation of certain branches is usually necessary. In addition, such occluded branches are the most important vessels during coronary interventions and obtaining motion models for these can greatly help in reducing the procedure time and radiation exposure. Segmenting different cardiac phases independently does not guarantee temporal consistency and is not efficient for occluded branches required manual segmentation. In this paper, we propose a coronary motion modeling system which extracts the coronary tree for every cardiac phase, maintaining the segmentation by tracking the coronary tree during the cardiac cycle. It is able to map every frame to the specific cardiac phase, thereby inferring the shape information of the coronary arteries using the model corresponding to its phase. Our experiments show that our motion modeling system can achieve promising results with real-time performance.

  3. Noisy images-JPEG compressed: subjective and objective image quality evaluation

    NASA Astrophysics Data System (ADS)

    Corchs, Silvia; Gasparini, Francesca; Schettini, Raimondo

    2014-01-01

    The aim of this work is to study image quality of both single and multiply distorted images. We address the case of images corrupted by Gaussian noise or JPEG compressed as single distortion cases and images corrupted by Gaussian noise and then JPEG compressed, as multiply distortion case. Subjective studies were conducted in two parts to obtain human judgments on the single and multiply distorted images. We study how these subjective data correlate with No Reference state-of-the-art quality metrics. We also investigate proper combining of No Reference metrics to achieve better performance. Results are analyzed and compared in terms of correlation coefficients.

  4. The effect of image quality and forensic expertise in facial image comparisons.

    PubMed

    Norell, Kristin; Läthén, Klas Brorsson; Bergström, Peter; Rice, Allyson; Natu, Vaidehi; O'Toole, Alice

    2015-03-01

    Images of perpetrators in surveillance video footage are often used as evidence in court. In this study, identification accuracy was compared for forensic experts and untrained persons in facial image comparisons as well as the impact of image quality. Participants viewed thirty image pairs and were asked to rate the level of support garnered from their observations for concluding whether or not the two images showed the same person. Forensic experts reached their conclusions with significantly fewer errors than did untrained participants. They were also better than novices at determining when two high-quality images depicted the same person. Notably, lower image quality led to more careful conclusions by experts, but not for untrained participants. In summary, the untrained participants had more false negatives and false positives than experts, which in the latter case could lead to a higher risk of an innocent person being convicted for an untrained witness. PMID:25537273

  5. Improving high resolution retinal image quality using speckle illumination HiLo imaging

    PubMed Central

    Zhou, Xiaolin; Bedggood, Phillip; Metha, Andrew

    2014-01-01

    Retinal image quality from flood illumination adaptive optics (AO) ophthalmoscopes is adversely affected by out-of-focus light scatter due to the lack of confocality. This effect is more pronounced in small eyes, such as that of rodents, because the requisite high optical power confers a large dioptric thickness to the retina. A recently-developed structured illumination microscopy (SIM) technique called HiLo imaging has been shown to reduce the effect of out-of-focus light scatter in flood illumination microscopes and produce pseudo-confocal images with significantly improved image quality. In this work, we adopted the HiLo technique to a flood AO ophthalmoscope and performed AO imaging in both (physical) model and live rat eyes. The improvement in image quality from HiLo imaging is shown both qualitatively and quantitatively by using spatial spectral analysis. PMID:25136486

  6. Automated coronary artery calcification detection on low-dose chest CT images

    NASA Astrophysics Data System (ADS)

    Xie, Yiting; Cham, Matthew D.; Henschke, Claudia; Yankelevitz, David; Reeves, Anthony P.

    2014-03-01

    Coronary artery calcification (CAC) measurement from low-dose CT images can be used to assess the risk of coronary artery disease. A fully automatic algorithm to detect and measure CAC from low-dose non-contrast, non-ECG-gated chest CT scans is presented. Based on the automatically detected CAC, the Agatston score (AS), mass score and volume score were computed. These were compared with scores obtained manually from standard-dose ECG-gated scans and low-dose un-gated scans of the same patient. The automatic algorithm segments the heart region based on other pre-segmented organs to provide a coronary region mask. The mitral valve and aortic valve calcification is identified and excluded. All remaining voxels greater than 180HU within the mask region are considered as CAC candidates. The heart segmentation algorithm was evaluated on 400 non-contrast cases with both low-dose and regular dose CT scans. By visual inspection, 371 (92.8%) of the segmentations were acceptable. The automated CAC detection algorithm was evaluated on 41 low-dose non-contrast CT scans. Manual markings were performed on both low-dose and standard-dose scans for these cases. Using linear regression, the correlation of the automatic AS with the standard-dose manual scores was 0.86; with the low-dose manual scores the correlation was 0.91. Standard risk categories were also computed. The automated method risk category agreed with manual markings of gated scans for 24 cases while 15 cases were 1 category off. For low-dose scans, the automatic method agreed with 33 cases while 7 cases were 1 category off.

  7. Objective Quality Assessment for Color-to-Gray Image Conversion.

    PubMed

    Ma, Kede; Zhao, Tiesong; Zeng, Kai; Wang, Zhou

    2015-12-01

    Color-to-gray (C2G) image conversion is the process of transforming a color image into a grayscale one. Despite its wide usage in real-world applications, little work has been dedicated to compare the performance of C2G conversion algorithms. Subjective evaluation is reliable but is also inconvenient and time consuming. Here, we make one of the first attempts to develop an objective quality model that automatically predicts the perceived quality of C2G converted images. Inspired by the philosophy of the structural similarity index, we propose a C2G structural similarity (C2G-SSIM) index, which evaluates the luminance, contrast, and structure similarities between the reference color image and the C2G converted image. The three components are then combined depending on image type to yield an overall quality measure. Experimental results show that the proposed C2G-SSIM index has close agreement with subjective rankings and significantly outperforms existing objective quality metrics for C2G conversion. To explore the potentials of C2G-SSIM, we further demonstrate its use in two applications: 1) automatic parameter tuning for C2G conversion algorithms and 2) adaptive fusion of C2G converted images. PMID:26208349

  8. Peripheral Aberrations and Image Quality for Contact Lens Correction

    PubMed Central

    Shen, Jie; Thibos, Larry N.

    2011-01-01

    Purpose Contact lenses reduced the degree of hyperopic field curvature present in myopic eyes and rigid contact lenses reduced sphero-cylindrical image blur on the peripheral retina, but their effect on higher order aberrations and overall optical quality of the eye in the peripheral visual field is still unknown. The purpose of our study was to evaluate peripheral wavefront aberrations and image quality across the visual field before and after contact lens correction. Methods A commercial Hartmann-Shack aberrometer was used to measure ocular wavefront errors in 5° steps out to 30° of eccentricity along the horizontal meridian in uncorrected eyes and when the same eyes are corrected with soft or rigid contact lenses. Wavefront aberrations and image quality were determined for the full elliptical pupil encountered in off-axis measurements. Results Ocular higher-order aberrations increase away from fovea in the uncorrected eye. Third-order aberrations are larger and increase faster with eccentricity compared to the other higher-order aberrations. Contact lenses increase all higher-order aberrations except 3rd-order Zernike terms. Nevertheless, a net increase in image quality across the horizontal visual field for objects located at the foveal far point is achieved with rigid lenses, whereas soft contact lenses reduce image quality. Conclusions Second order aberrations limit image quality more than higher-order aberrations in the periphery. Although second-order aberrations are reduced by contact lenses, the resulting gain in image quality is partially offset by increased amounts of higher-order aberrations. To fully realize the benefits of correcting higher-order aberrations in the peripheral field requires improved correction of second-order aberrations as well. PMID:21873925

  9. A Dynamic Image Quality Evaluation of Videofluoroscopy Images: Considerations for Telepractice Applications.

    PubMed

    Burns, Clare L; Keir, Benjamin; Ward, Elizabeth C; Hill, Anne J; Farrell, Anna; Phillips, Nick; Porter, Linda

    2015-08-01

    High-quality fluoroscopy images are required for accurate interpretation of videofluoroscopic swallow studies (VFSS) by speech pathologists and radiologists. Consequently, integral to developing any system to conduct VFSS remotely via telepractice is ensuring that the quality of the VFSS images transferred via the telepractice system is optimized. This study evaluates the extent of change observed in image quality when videofluoroscopic images are transmitted from a digital fluoroscopy system to (a) current clinical equipment (KayPentax Digital Swallowing Workstation, and b) four different telepractice system configurations. The telepractice system configurations consisted of either a local C20 or C60 Cisco TelePresence System (codec unit) connected to the digital fluoroscopy system and linked to a second remote C20 or C60 Cisco TelePresence System via a network running at speeds of either 2, 4 or 6 megabits per second (Mbit/s). Image quality was tested using the NEMA XR 21 Phantom, and results demonstrated some loss in spatial resolution, low contrast detectability and temporal resolution for all transferred images when compared to the fluoroscopy source. When using higher capacity codec units and/or the highest bandwidths to support data transmission, image quality transmitted through the telepractice system was found to be comparable if not better than the current clinical system. This study confirms that telepractice systems can be designed to support fluoroscopy image transfer and highlights important considerations when developing telepractice systems for VFSS analysis to ensure high-quality radiological image reproduction. PMID:26014137

  10. [Small imaging spectrometer for the inspection of fruit quality].

    PubMed

    Liu, Yu-juan; Tang, Yu-guo; Cui, Ji-cheng; Bayanheshig

    2012-01-01

    Imaging spectrometer can acquire spatial and spectral information of the target at the same time, achieve high-precision, non-destructive, non-contamination and large area instantaneous inspection of the fruit. In order to get the imaging spectrum of the fruit, compact imaging spectrometer with convex grating produced by self was designed, it has the advantages of good performance, small volume and low weight, its resolution at 578 nm is 2.1 nm, and spectral line bend and chromatic distortion are both smaller than 0.6%. Laboratory test of the imaging spectrometer and the experiment of getting the imaging spectrum of apple were done, and the result shows that the imaging spectrometer satisfies the design requirement and can acquire the imaging spectrum of apple rapidly with high precision for inspection of fruit quality. PMID:22497177

  11. High dynamic range image compression by optimizing tone mapped image quality index.

    PubMed

    Ma, Kede; Yeganeh, Hojatollah; Zeng, Kai; Wang, Zhou

    2015-10-01

    Tone mapping operators (TMOs) aim to compress high dynamic range (HDR) images to low dynamic range (LDR) ones so as to visualize HDR images on standard displays. Most existing TMOs were demonstrated on specific examples without being thoroughly evaluated using well-designed and subject-validated image quality assessment models. A recently proposed tone mapped image quality index (TMQI) made one of the first attempts on objective quality assessment of tone mapped images. Here, we propose a substantially different approach to design TMO. Instead of using any predefined systematic computational structure for tone mapping (such as analytic image transformations and/or explicit contrast/edge enhancement), we directly navigate in the space of all images, searching for the image that optimizes an improved TMQI. In particular, we first improve the two building blocks in TMQI—structural fidelity and statistical naturalness components—leading to a TMQI-II metric. We then propose an iterative algorithm that alternatively improves the structural fidelity and statistical naturalness of the resulting image. Numerical and subjective experiments demonstrate that the proposed algorithm consistently produces better quality tone mapped images even when the initial images of the iteration are created by the most competitive TMOs. Meanwhile, these results also validate the superiority of TMQI-II over TMQI. PMID:26011881

  12. Body image and quality of life in a Spanish population

    PubMed Central

    Lobera, Ignacio Jáuregui; Ríos, Patricia Bolaños

    2011-01-01

    Purpose The aim of the current study was to analyze the psychometric properties, factor structure, and internal consistency of the Spanish version of the Body Image Quality of Life Inventory (BIQLI-SP) as well as its test–retest reliability. Further objectives were to analyze different relationships with key dimensions of psychosocial functioning (ie, self-esteem, presence of psychopathological symptoms, eating and body image-related problems, and perceived stress) and to evaluate differences in body image quality of life due to gender. Patients and methods The sample comprised 417 students without any psychiatric history, recruited from the Pablo de Olavide University and the University of Seville. There were 140 men (33.57%) and 277 women (66.43%), and the mean age was 21.62 years (standard deviation = 5.12). After obtaining informed consent from all participants, the following questionnaires were administered: BIQLI, Eating Disorder Inventory-2 (EDI-2), Perceived Stress Questionnaire (PSQ), Self-Esteem Scale (SES), and Symptom Checklist-90-Revised (SCL-90-R). Results The BIQLI-SP shows adequate psychometric properties, and it may be useful to determine the body image quality of life in different physical conditions. A more positive body image quality of life is associated with better self-esteem, better psychological wellbeing, and fewer eating-related dysfunctional attitudes, this being more evident among women. Conclusion The BIQLI-SP may be useful to determine the body image quality of life in different contexts with regard to dermatology, cosmetic and reconstructive surgery, and endocrinology, among others. In these fields of study, a new trend has emerged to assess body image-related quality of life. PMID:21403794

  13. Analysis of image quality for laser display scanner test

    NASA Astrophysics Data System (ADS)

    Specht, H.; Kurth, S.; Billep, D.; Gessner, T.

    2009-02-01

    The scanning laser display technology is one of the most promising technologies for highly integrated projection display applications (e. g. in PDAs, mobile phones or head mounted displays) due to its advantages regarding image quality, miniaturization level and low cost potential. As a couple of research teams found during their investigations on laser scanning projections systems, the image quality of such systems is - beside from laser source and video signal processing - crucially determined by the scan engine, including MEMS scanner, driving electronics, scanning regime and synchronization. Even though a number of technical parameters can be measured with high accuracy, the test procedure is challenging because the influence of these parameters on image quality is often insufficiently understood. Thus, in many cases it is not clear how to define limiting values for characteristic parameters. In this paper the relationship between parameters characterizing the scan engine and their influence on image quality will be discussed. Those include scanner topography, geometry of the path of light as well as trajectory parameters. Understanding this enables a new methodology for testing and characterization of the scan engine, based on evaluation of one or a series of projected test images. Due to the fact that the evaluation process can be easily automated by digital image processing this methodology has the potential to become integrated into the production process of laser displays.

  14. Construction of realistic liver phantoms from patient images using 3D printer and its application in CT image quality assessment

    NASA Astrophysics Data System (ADS)

    Leng, Shuai; Yu, Lifeng; Vrieze, Thomas; Kuhlmann, Joel; Chen, Baiyu; McCollough, Cynthia H.

    2015-03-01

    The purpose of this study is to use 3D printing techniques to construct a realistic liver phantom with heterogeneous background and anatomic structures from patient CT images, and to use the phantom to assess image quality with filtered back-projection and iterative reconstruction algorithms. Patient CT images were segmented into liver tissues, contrast-enhanced vessels, and liver lesions using commercial software, based on which stereolithography (STL) files were created and sent to a commercial 3D printer. A 3D liver phantom was printed after assigning different printing materials to each object to simulate appropriate attenuation of each segmented object. As high opacity materials are not available for the printer, we printed hollow vessels and filled them with iodine solutions of adjusted concentration to represent enhance levels in contrast-enhanced liver scans. The printed phantom was then placed in a 35×26 cm oblong-shaped water phantom and scanned repeatedly at 4 dose levels. Images were reconstructed using standard filtered back-projection and an iterative reconstruction algorithm with 3 different strength settings. Heterogeneous liver background were observed from the CT images and the difference in CT numbers between lesions and background were representative for low contrast lesions in liver CT studies. CT numbers in vessels filled with iodine solutions represented the enhancement of liver arteries and veins. Images were run through a Channelized Hotelling model observer with Garbor channels and ROC analysis was performed. The AUC values showed performance improvement using the iterative reconstruction algorithm and the amount of improvement increased with strength setting.

  15. Image quality assessment with manifold and machine learning

    NASA Astrophysics Data System (ADS)

    Charrier, Christophe; Lebrun, Gilles; Lezoray, Olivier

    2009-01-01

    A crucial step in image compression is the evaluation of its performance, and more precisely the available way to measure the final quality of the compressed image. In this paper, a machine learning expert, providing a final class number is designed. The quality measure is based on a learned classification process in order to respect the one of human observers. Instead of computing a final note, our method classifies the quality using the quality scale recommended by the UIT. This quality scale contains 5 ranks ordered from 1 (the worst quality) to 5 (the best quality). This was done constructing a vector containing many visual attributes. Finally, the final features vector contains more than 40 attibutes. Unfortunatley, no study about the existing interactions between the used visual attributes has been done. A feature selection algorithm could be interesting but the selection is highly related to the further used classifier. Therefore, we prefer to perform dimensionality reduction instead of feature selection. Manifold Learning methods are used to provide a low-dimensional new representation from the initial high dimensional feature space. The classification process is performed on this new low-dimensional representation of the images. Obtained results are compared to the one obtained without applying the dimension reduction process to judge the efficiency of the method.

  16. Toward the development of an image quality tool for active millimeter wave imaging systems

    NASA Astrophysics Data System (ADS)

    Barber, Jeffrey; Weatherall, James C.; Greca, Joseph; Smith, Barry T.

    2015-05-01

    Preliminary design considerations for an image quality tool to complement millimeter wave imaging systems are presented. The tool is planned for use in confirming operating parameters; confirmation of continuity for imaging component design changes, and analysis of new components and detection algorithms. Potential embodiments of an image quality tool may contain materials that mimic human skin in order to provide a realistic signal return for testing, which may also help reduce or eliminate the need for mock passengers for developmental testing. Two candidate materials, a dielectric liquid and an iron-loaded epoxy, have been identified and reflection measurements have been performed using laboratory systems in the range 18 - 40 GHz. Results show good agreement with both laboratory and literature data on human skin, particularly in the range of operation of two commercially available millimeter wave imaging systems. Issues related to the practical use of liquids and magnetic materials for image quality tools are discussed.

  17. Perceptual image quality in normalized LOG domain for Adaptive Optics image post-processing

    NASA Astrophysics Data System (ADS)

    Guo, Shiping; Zhang, Rongzhi; Li, Jisheng; Zou, Jianhua; Liu, Changhai; Gao, Weizhe

    2015-08-01

    Adaptive Optics together with subsequent post-processing techniques obviously improve the resolution of turbulencedegraded images in ground-based space objects detection and identification. The most common method for frame selection and stopping iteration in post-processing has always been subjective viewing of the images due to a lack of widely agreed-upon objective quality metric. Full reference metrics are not applicable for assessing the field data, no-reference metrics tend to perform poor sensitivity for Adaptive Optics images. In the present work, based on the Laplacian of Gaussian (LOG) local contrast feature, a nonlinear normalization is applied to transform the input image into a normalized LOG domain; a quantitative index is then extracted in this domain to assess the perceptual image quality. Experiments show this no-reference quality index is highly consistent with the subjective evaluation of input images for different blur degree and different iteration number.

  18. Four-dimensional Transcatheter Intra-arterial Perfusion MR Imaging Before and After Uterine Artery Embolization in the Rabbit VX2 Tumor Model

    PubMed Central

    Chung, Johnathan C.; Wang, Dingxin; Lewandowski, Robert J.; Tang, Richard; Chrisman, Howard B.; Vogelzang, Robert L.; Woloschak, Gayle E.; Larson, Andrew C.; Omary, Reed A.; Ryu, Robert K.

    2010-01-01

    Purpose To test the hypothesis that four-dimensional (4D) transcatheter intra-arterial perfusion (TRIP) MR imaging can measure uterine fibroid perfusion changes immediately before and after uterine artery embolization (UAE) in the rabbit VX2 tumor model. Materials and Methods Eight VX2 uterine tumors were grown in 6 rabbits. After positioning a catheter within the uterine artery, we performed 4D TRIP-MRI measurements with 3 mL injections of 2.5% gadopentetate dimeglumine. We used a dynamic 3D spoiled-GRE sequence with in vivo B1-field correction for improved accuracy during perfusion quantification. We performed UAE using 1 mL of gelatin microspheres (2×106 particles; diameter 40-120 ?m). Two regions-of-interest were drawn within each tumor upon perfusion maps. Functional embolic endpoints were reported as the mean percent reduction in fibroid tumor perfusion. Measurements before and after UAE were compared using paired t-tests (? = 0.05). Results VX2 uterine tumor perfusion decreased significantly from 27.1 at baseline to 7.09 after UAE (mL/min/100 mL tissue, p < 0.0001). Overall perfusion reduction was 76.3% (95% CI: 66.3%-86.3%). Conclusion 4D TRIP MRI can objectively quantify uterine fibroid perfusion reductions during UAE in VX2 rabbits. This technique could be used clinically to potentially determine an optimal embolic endpoint with the long-term goals of improving UAE success rates and minimizing procedure-related ischemic pain. PMID:20432349

  19. Thematic Mapper image quality: Preliminary results

    NASA Technical Reports Server (NTRS)

    Wrigley, R. C.; Card, D. H.; Hlavka, C. A.; Likens, W. C.; Mertz, F. C.; Hall, J. R.

    1983-01-01

    Based on images analyzed so far, the band to band registration accuracy of the thematic mapper is very good. For bands within the same focal plane, the mean misregistrations are well within the specification, 0.2 pixels. For bands between the cooled and uncooled focal planes, there is a consistent mean misregistration of 0.5 pixels along-scan and 0.2-0.3 pixels across-scan. It exceeds the permitted 0.3 pixels for registration of bands between focal planes. If the mean misregistrations were removed by the data processing software, an analysis of the standard deviation of the misregistration indicates all band combinations would meet the registration specifications except for those including the thermal band. Analysis of the periodic noise in one image indicates a noise component in band 1 with a spatial frequency equivalent to 3.2 pixels in the along-scan direction.

  20. APQ-102 imaging radar digital image quality study

    NASA Technical Reports Server (NTRS)

    Griffin, C. R.; Estes, J. M.

    1982-01-01

    A modified APQ-102 sidelooking radar collected synthetic aperture radar (SAR) data which was digitized and recorded on wideband magnetic tape. These tapes were then ground processed into computer compatible tapes (CCT's). The CCT's may then be processed into high resolution radar images by software on the CYBER computer.

  1. Exploratory survey of image quality on CR digital mammography imaging systems in Mexico.

    PubMed

    Gaona, E; Rivera, T; Arreola, M; Franco, J; Molina, N; Alvarez, B; Azorín, C G; Casian, G

    2014-01-01

    The purpose of this study was to assess the current status of image quality and dose in computed radiographic digital mammography (CRDM) systems. Studies included CRDM systems of various models and manufacturers which dose and image quality comparisons were performed. Due to the recent rise in the use of digital radiographic systems in Mexico, CRDM systems are rapidly replacing conventional film-screen systems without any regard to quality control or image quality standards. Study was conducted in 65 mammography facilities which use CRDM systems in the Mexico City and surrounding States. The systems were tested as used clinically. This means that the dose and beam qualities were selected using the automatic beam selection and photo-timed features. All systems surveyed generate laser film hardcopies for the radiologist to read on a scope or mammographic high luminance light box. It was found that 51 of CRDM systems presented a variety of image artefacts and non-uniformities arising from inadequate acquisition and processing, as well as from the laser printer itself. Undisciplined alteration of image processing settings by the technologist was found to be a serious prevalent problem in 42 facilities. Only four of them showed an image QC program which is periodically monitored by a medical physicist. The Average Glandular Dose (AGD) in the surveyed systems was estimated to have a mean value of 2.4 mGy. To improve image quality in mammography and make more efficient screening mammographic in early detection of breast cancer is required new legislation. PMID:23938078

  2. Investigation of perceptual attributes for mobile display image quality

    NASA Astrophysics Data System (ADS)

    Gong, Rui; Xu, Haisong; Wang, Qing; Wang, Zhehong; Li, Haifeng

    2013-08-01

    Large-scale psychophysical experiments are carried out on two types of mobile displays to evaluate the perceived image quality (IQ). Eight perceptual attributes, i.e., naturalness, colorfulness, brightness, contrast, sharpness, clearness, preference, and overall IQ, are visually assessed via categorical judgment method for various application types of test images, which were manipulated by different methods. Their correlations are deeply discussed, and further factor analysis revealed the two essential components to describe the overall IQ, i.e., the component of image detail aspect and the component of color information aspect. Clearness and naturalness are regarded as two principal factors for natural scene images, whereas clearness and colorfulness were selected as key attributes affecting the overall IQ for other application types of images. Accordingly, based on these selected attributes, two kinds of empirical models are built to predict the overall IQ of mobile displays for different application types of images.

  3. Optimage central organised image quality control including statistics and reporting.

    PubMed

    Jahnen, A; Schilz, C; Shannoun, F; Schreiner, A; Hermen, J; Moll, C

    2008-01-01

    Quality control of medical imaging systems is performed using dedicated phantoms. As the imaging systems are more and more digital, adequate image processing methods might help to save evaluation time and to receive objective results. The developed software package OPTIMAGE is focusing on this with a central approach: On one hand, OPTIMAGE provides a framework, which includes functions like database integration, DICOM data sources, multilingual user interface and image processing functionality. On the other hand, the test methods are implemented using modules which are able to process the images automatically for the common imaging systems. The integration of statistics and reporting into this environment is paramount: This is the only way to provide these functions in an interactive, user-friendly way. These features enable the users to discover degradation in performance quickly and document performed measurements easily. PMID:18252849

  4. Real-time computer treatment of THz passive device images with the high image quality

    NASA Astrophysics Data System (ADS)

    Trofimov, Vyacheslav A.; Trofimov, Vladislav V.

    2012-06-01

    We demonstrate real-time computer code improving significantly the quality of images captured by the passive THz imaging system. The code is not only designed for a THz passive device: it can be applied to any kind of such devices and active THz imaging systems as well. We applied our code for computer processing of images captured by four passive THz imaging devices manufactured by different companies. It should be stressed that computer processing of images produced by different companies requires using the different spatial filters usually. The performance of current version of the computer code is greater than one image per second for a THz image having more than 5000 pixels and 24 bit number representation. Processing of THz single image produces about 20 images simultaneously corresponding to various spatial filters. The computer code allows increasing the number of pixels for processed images without noticeable reduction of image quality. The performance of the computer code can be increased many times using parallel algorithms for processing the image. We develop original spatial filters which allow one to see objects with sizes less than 2 cm. The imagery is produced by passive THz imaging devices which captured the images of objects hidden under opaque clothes. For images with high noise we develop an approach which results in suppression of the noise after using the computer processing and we obtain the good quality image. With the aim of illustrating the efficiency of the developed approach we demonstrate the detection of the liquid explosive, ordinary explosive, knife, pistol, metal plate, CD, ceramics, chocolate and other objects hidden under opaque clothes. The results demonstrate the high efficiency of our approach for the detection of hidden objects and they are a very promising solution for the security problem.

  5. Predicting Cerebral Hyperperfusion Syndrome Following Superficial Temporal Artery to Middle Cerebral Artery Bypass based on Intraoperative Perfusion-Weighted Magnetic Resonance Imaging

    PubMed Central

    Wang, Defeng; Zhu, Fengping; Fung, Ka Ming; Zhu, Wei; Luo, Yishan; Chu, Winnie Chiu Wing; Tong Mok, Vincent Chung; Wu, Jinsong; Shi, Lin; Ahuja, Anil T.; Mao, Ying

    2015-01-01

    Moyamoya disease leads to the formation of stenosis in the cerebrovasculature. A superficial temporal artery to middle cerebral artery (STA-MCA) bypass is an effective treatment for the disease, yet it is usually associated with postoperative cerebral hyperperfusion syndrome (CHS). This study aimed to evaluate cerebral hemodynamic changes immediately after surgery and assess whether a semiquantitative analysis of an intraoperative magnetic resonance perfusion-weighted image (PWI) is useful for predicting postoperative CHS. Fourteen patients who underwent the STA-MCA bypass surgery were included in this study. An atlas-based registration method was employed for studying hemodynamics in different cerebral regions. Pre- versus intraoperative and group-wise comparisons were conducted to evaluate the hemodynamic changes. A postoperative increase in relative cerebral blood flow (CBF) at the terminal MCA territory (P?=?0.035) and drop in relative mean-time-transit at the central MCA territory (P?=?0.012) were observed in all patients. However, a significant raise in the increasing ratio of relative-CBF at the terminal MCA territory was only found in CHS patients (P?=?0.023). The cerebrovascular changes of the patients after revascularization treatment were confirmed. Intraoperative PWI might be helpful in predicting the change in relative-CBF at MCA terminal territory which might indicate a risk of CHS. PMID:26365751

  6. Semi-automated segmentation of carotid artery total plaque volume from three dimensional ultrasound carotid imaging

    NASA Astrophysics Data System (ADS)

    Buchanan, D.; Gyacskov, I.; Ukwatta, E.; Lindenmaier, T.; Fenster, A.; Parraga, G.

    2012-03-01

    Carotid artery total plaque volume (TPV) is a three-dimensional (3D) ultrasound (US) imaging measurement of carotid atherosclerosis, providing a direct non-invasive and regional estimation of atherosclerotic plaque volume - the direct determinant of carotid stenosis and ischemic stroke. While 3DUS measurements of TPV provide the potential to monitor plaque in individual patients and in populations enrolled in clinical trials, until now, such measurements have been performed manually which is laborious, time-consuming and prone to intra-observer and inter-observer variability. To address this critical translational limitation, here we describe the development and application of a semi-automated 3DUS plaque volume measurement. This semi-automated TPV measurement incorporates three user-selected boundaries in two views of the 3DUS volume to generate a geometric approximation of TPV for each plaque measured. We compared semi-automated repeated measurements to manual segmentation of 22 individual plaques ranging in volume from 2mm3 to 151mm3. Mean plaque volume was 43+/-40mm3 for semi-automated and 48+/-46mm3 for manual measurements and these were not significantly different (p=0.60). Mean coefficient of variation (CV) was 12.0+/-5.1% for the semi-automated measurements.

  7. Effect of Arterial Deprivation on Growing Femoral Epiphysis: Quantitative Magnetic Resonance Imaging Using a Piglet Model

    PubMed Central

    Cheon, Jung-Eun; Kim, In-One; Kim, Woo Sun; Choi, Young Hun

    2015-01-01

    Objective To investigate the usefulness of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion MRI for the evaluation of femoral head ischemia. Materials and Methods Unilateral femoral head ischemia was induced by selective embolization of the medial circumflex femoral artery in 10 piglets. All MRIs were performed immediately (1 hour) and after embolization (1, 2, and 4 weeks). Apparent diffusion coefficients (ADCs) were calculated for the femoral head. The estimated pharmacokinetic parameters (Kep and Ve from two-compartment model) and semi-quantitative parameters including peak enhancement, time-to-peak (TTP), and contrast washout were evaluated. Results The epiphyseal ADC values of the ischemic hip decreased immediately (1 hour) after embolization. However, they increased rapidly at 1 week after embolization and remained elevated until 4 weeks after embolization. Perfusion MRI of ischemic hips showed decreased epiphyseal perfusion with decreased Kep immediately after embolization. Signal intensity-time curves showed delayed TTP with limited contrast washout immediately post-embolization. At 1-2 weeks after embolization, spontaneous reperfusion was observed in ischemic epiphyses. The change of ADC (p = 0.043) and Kep (p = 0.043) were significantly different between immediate (1 hour) after embolization and 1 week post-embolization. Conclusion Diffusion MRI and pharmacokinetic model obtained from the DCE-MRI are useful in depicting early changes of perfusion and tissue damage using the model of femoral head ischemia in skeletally immature piglets. PMID:25995692

  8. Image-Processing Techniques for the Creation of Presentation-Quality Astronomical Images

    E-print Network

    Rector, T A; Frattare, L M; English, J; Puuohau-Pummill, K

    2004-01-01

    The quality of modern astronomical data, the power of modern computers and the agility of current image-processing software enable the creation of high-quality images in a purely digital form. The combination of these technological advancements has created a new ability to make color astronomical images. And in many ways it has led to a new philosophy towards how to create them. A practical guide is presented on how to generate astronomical images from research data with powerful image-processing programs. These programs use a layering metaphor that allows for an unlimited number of astronomical datasets to be combined in any desired color scheme, creating an immense parameter space to be explored using an iterative approach. Several examples of image creation are presented. A philosophy is also presented on how to use color and composition to create images that simultaneously highlight scientific detail and are aesthetically appealing. This philosophy is necessary because most datasets do not correspond to t...

  9. Combined MR imaging and numerical simulation of flow in realistic arterial bypass graft models.

    PubMed

    Papaharilaou, Y; Doorly, D J; Sherwin, S J; Peiro, J; Griffith, C; Cheshire, N; Zervas, V; Anderson, J; Sanghera, B; Watkins, N; Caro, C G

    2002-01-01

    We report methods for (a) transforming a three-dimensional geometry acquired by magnetic resonance angiography (MRA) in vivo, or by imaging a model cast, into a computational surface representation, (b) use of this to construct a three dimensional numerical grid for computational fluid dynamic (CFD) studies, and (c) use of the surface representation to produce a stereo-lithographic replica of the real detailed geometry, at a scale convenient for detailed magnetic resonance imaging (MRI) flow studies. This is applied to assess the local flow field in realistic geometry arterial bypass grafts. Results from a parallel numerical simulation and MRI measurement of flow in an aorto-coronary bypass graft with various inlet flow conditions demonstrate the strong influence of the graft inlet waveform on the perianastomotic flow field. A sinusoidal and a multi harmonic coronary flow waveform both with a mean Reynolds number (Re) of 100 and a Womersley parameter of 2.7 were applied at the graft inlet. A weak axial flow separation region just distal to the toe was found in sinusoidal flow near end deceleration (Re = 25). At the same location and approximately the same point in the cycle (Re = 30) but in coronary flow, the axial flow separation was stronger and more spatially pronounced. No axial flow separation occurred in steady flow for Re = 100. Numerical predictions indicate a region in the vicinity of the suture line (where there is a local narrowing of the graft) with a wall shear magnitude in excess of five times that associated with fully developed flow at the graft inlet. PMID:12122276

  10. Closed-chest animal model of chronic coronary artery stenosis. Assessment with magnetic resonance imaging.

    PubMed

    Wu, Ming; Bogaert, Jan; D'hooge, Jan; Sipido, Karin; Maes, Frederik; Dymarkowski, Steven; Rademakers, Frank E; Claus, Piet

    2010-03-01

    To evaluate the consequences of chronic non-occlusive coronary artery (CA) stenosis on myocardial function, perfusion and viability, we developed a closed-chest, closed-pericardium pig model, using magnetic resonance imaging (MRI) as quantitative imaging tool. Pigs underwent a percutaneous copper-coated stent implantation in the left circumflex CA (n = 19) or sham operation (n = 5). To evaluate the occurrence of myocardial infarction, cardiac troponin I (cTnI) levels were repetitively measured. At week 6, CA stenosis severity was quantified with angiography and cine, first-pass and contrast-enhanced MRI were performed to evaluate cardiac function, perfusion and viability. In the stenting group, cTnI values significantly increased at day 3 and day 5 (P = 0.01), and normalized at day 12. At angiography, 13/19 stented pigs had a stenosis >75%. Mean degree of CA stenosis was 91 +/- 4%, range 83-98%. At contrast-enhanced MRI, mean infarct size was 7 +/- 6%, range 0.7-18.4%. Five of the 6 pigs with stenosis <75% had no infarction. Stented pigs showed significantly higher Left-ventricular volumes and normalized mass (P < 0.05), and lower ejection fraction (P = 0.03) than the sham pigs. Both wall thickening and myocardial perfusion were significantly lower in animals with at least one segment >50% infarct (23 +/- 8%; 0.05 +/- 0.01 a.u./s) and animals with only <50% infarct segments (29% +/- 12%; 0.07 +/- 0.02 a.u./s), than sham pigs (52 +/- 6%; 0.10 +/- 0.03 a.u./s) (P < 0.001; P < 0.05). This minimally-invasive animal model of chronic, non-occlusive CA stenosis, presenting a mixture of perfusion and functional impairment and a variable degree of myocardial necrosis, can be used as substitute to study chronic myocardial hypoperfusion. PMID:20012206

  11. Radiation dose and image quality for paediatric interventional cardiology

    NASA Astrophysics Data System (ADS)

    Vano, E.; Ubeda, C.; Leyton, F.; Miranda, P.

    2008-08-01

    Radiation dose and image quality for paediatric protocols in a biplane x-ray system used for interventional cardiology have been evaluated. Entrance surface air kerma (ESAK) and image quality using a test object and polymethyl methacrylate (PMMA) phantoms have been measured for the typical paediatric patient thicknesses (4-20 cm of PMMA). Images from fluoroscopy (low, medium and high) and cine modes have been archived in digital imaging and communications in medicine (DICOM) format. Signal-to-noise ratio (SNR), figure of merit (FOM), contrast (CO), contrast-to-noise ratio (CNR) and high contrast spatial resolution (HCSR) have been computed from the images. Data on dose transferred to the DICOM header have been used to test the values of the dosimetric display at the interventional reference point. ESAK for fluoroscopy modes ranges from 0.15 to 36.60 µGy/frame when moving from 4 to 20 cm PMMA. For cine, these values range from 2.80 to 161.10 µGy/frame. SNR, FOM, CO, CNR and HCSR are improved for high fluoroscopy and cine modes and maintained roughly constant for the different thicknesses. Cumulative dose at the interventional reference point resulted 25-45% higher than the skin dose for the vertical C-arm (depending of the phantom thickness). ESAK and numerical image quality parameters allow the verification of the proper setting of the x-ray system. Knowing the increases in dose per frame when increasing phantom thicknesses together with the image quality parameters will help cardiologists in the good management of patient dose and allow them to select the best imaging acquisition mode during clinical procedures.

  12. Dose and diagnostic image quality in digital tomosynthesis imaging of facial bones in pediatrics

    NASA Astrophysics Data System (ADS)

    King, J. M.; Hickling, S.; Elbakri, I. A.; Reed, M.; Wrogemann, J.

    2011-03-01

    The purpose of this study was to evaluate the use of digital tomosynthesis (DT) for pediatric facial bone imaging. We compared the eye lens dose and diagnostic image quality of DT facial bone exams relative to digital radiography (DR) and computed tomography (CT), and investigated whether we could modify our current DT imaging protocol to reduce patient dose while maintaining sufficient diagnostic image quality. We measured the dose to the eye lens for all three modalities using high-sensitivity thermoluminescent dosimeters (TLDs) and an anthropomorphic skull phantom. To assess the diagnostic image quality of DT compared to the corresponding DR and CT images, we performed an observer study where the visibility of anatomical structures in the DT phantom images were rated on a four-point scale. We then acquired DT images at lower doses and had radiologists indicate whether the visibility of each structure was adequate for diagnostic purposes. For typical facial bone exams, we measured eye lens doses of 0.1-0.4 mGy for DR, 0.3-3.7 mGy for DT, and 26 mGy for CT. In general, facial bone structures were visualized better with DT then DR, and the majority of structures were visualized well enough to avoid the need for CT. DT imaging provides high quality diagnostic images of the facial bones while delivering significantly lower doses to the lens of the eye compared to CT. In addition, we found that by adjusting the imaging parameters, the DT effective dose can be reduced by up to 50% while maintaining sufficient image quality.

  13. Compensatory enlargement of human coronary arteries identified by magnetic resonance imaging.

    PubMed

    Bertini, P J; Parga, J R; Chagas, A C P; Rochitte, C E; Avila, L F; Favarato, D; Luz, P L da

    2005-05-01

    The aim of the present study was to evaluate the role of magnetic resonance imaging (MRI) for the non-invasive detection of coronary abnormalities and specifically the remodeling process in patients with coronary artery disease (CAD). MRI was performed in 10 control healthy subjects and 26 patients with angiographically proven CAD of the right coronary (RCA) or left anterior descending (LAD) artery; 23 patients were within two months of acute coronary syndromes, and 3 had stable angina with a positive test for ischemia. Wall thickness (WT), vessel wall area (VWA), total vessel area (TVA), and luminal area (LA) were measured. There were significant increases in WT (mean +/- SEM, RCA: 2.62 +/- 0.75 vs 0.53 +/- 0.15 mm; LAD: 2.21 +/- 0.69 vs 0.62 +/- 0.24 mm) and in VWA (RCA: 30.96 +/- 17.57 vs 2.1 +/- 1.2 mm(2); LAD: 19.53 +/- 7.25 vs 3.6 +/- 2.0 mm(2)) patients compared to controls (P < 0.001 for each variable). TVA values were also greater in patients compared to controls (RCA: 44.56 +/- 21.87 vs 12.3 +/- 4.2 mm(2); LAD: 31.89 +/- 11.31 vs 17.0 +/- 6.2 mm(2); P < 0.001). In contrast, the LA did not differ between patients and controls for RCA or LAD. When the LA was adjusted for vessel size using the LA/TVA ratio, a significant difference was found: 0.33 +/- 0.16 in patients vs 0.82 +/- 0.09 in controls (RCA) and 0.38 +/- 0.13 vs 0.78 +/- 0.06 (LAD) (P < 0.001). As opposed to normal controls, positive remodeling was present in all patients with CAD, as indicated by larger VWA. We conclude that MRI detected vessel wall abnormalities and was an effective tool for the noninvasive evaluation of the atherosclerotic process and coronary vessel wall modifications, including positive remodeling that frequently occurs in patients with acute coronary syndromes. PMID:15917946

  14. Coronary artery computed tomography as the first-choice imaging diagnostics in patients with high pre-test probability of coronary artery disease (CAT-CAD)

    PubMed Central

    Rudzi?ski, Piotr N.; Demkow, Marcin; Dzieli?ska, Zofia; Pr?gowski, Jerzy; Witkowski, Adam; Ru?y??o, Witold; K?pka, Cezary

    2015-01-01

    Introduction The primary diagnostic examination performed in patients with a high pre-test probability of coronary artery disease (CAD) is invasive coronary angiography. Currently, approximately 50% of all invasive coronary angiographies do not end with percutaneous coronary intervention (PCI) because of the absence of significant coronary artery lesions. It is desirable to eliminate such situations. There is an alternative, non-invasive method useful for exclusion of significant CAD, which is coronary computed tomography angiography (CCTA). Aim We hypothesize that use of CCTA as the first choice method in the diagnosis of patients with high pre-test probability of CAD may reduce the number of invasive coronary angiographies not followed by interventional treatment. Coronary computed tomography angiography also seems not to be connected with additional risks and costs of the diagnosis. Confirmation of these assumptions may impact cardiology guidelines. Material and methods One hundred and twenty patients with indications for invasive coronary angiography determined by current ESC guidelines regarding stable CAD are randomized 1 : 1 to classic invasive coronary angiography group and the CCTA group. Results All patients included in the study are monitored for the occurrence of possible end points during the diagnostic and therapeutic cycle (from the first imaging examination to either complete revascularization or disqualification from the invasive treatment), or during the follow-up period. Conclusions Based on the literature, it appears that the use of modern CT systems in patients with high pre-test probability of CAD, as well as appropriate clinical interpretation of the imaging study by invasive cardiologists, enables precise planning of invasive therapeutic procedures. Our randomized study will provide data to verify these assumptions. PMID:26677376

  15. Body image quality of life in eating disorders

    PubMed Central

    Jáuregui Lobera, Ignacio; Bolaños Ríos, Patricia

    2011-01-01

    Purpose: The objective was to examine how body image affects quality of life in an eating-disorder (ED) clinical sample, a non-ED clinical sample, and a nonclinical sample. We hypothesized that ED patients would show the worst body image quality of life. We also hypothesized that body image quality of life would have a stronger negative association with specific ED-related variables than with other psychological and psychopathological variables, mainly among ED patients. On the basis of previous studies, the influence of gender on the results was explored, too. Patients and methods: The final sample comprised 70 ED patients (mean age 22.65 ± 7.76 years; 59 women and 11 men); 106 were patients with other psychiatric disorders (mean age 28.20 ± 6.52; 67 women and 39 men), and 135 were university students (mean age 21.57 ± 2.58; 81 women and 54 men), with no psychiatric history. After having obtained informed consent, the following questionnaires were administered: Body Image Quality of Life Inventory-Spanish version (BIQLI-SP), Eating Disorders Inventory-2 (EDI-2), Perceived Stress Questionnaire (PSQ), Self-Esteem Scale (SES), and Symptom Checklist-90-Revised (SCL-90-R). Results: The ED patients’ ratings on the BIQLI-SP were the lowest and negatively scored (BIQLI-SP means: +20.18, +5.14, and ?6.18, in the student group, the non-ED patient group, and the ED group, respectively). The effect of body image on quality of life was more negative in the ED group in all items of the BIQLI-SP. Body image quality of life was negatively associated with specific ED-related variables, more than with other psychological and psychopathological variables, but not especially among ED patients. Conclusion: Body image quality of life was affected not only by specific pathologies related to body image disturbances, but also by other psychopathological syndromes. Nevertheless, the greatest effect was related to ED, and seemed to be more negative among men. This finding is the opposite of that found in other groups studied previously. PMID:21448468

  16. Flattening filter removal for improved image quality of megavoltage fluoroscopy

    SciTech Connect

    Christensen, James D.; Kirichenko, Alexander; Gayou, Olivier

    2013-08-15

    Purpose: Removal of the linear accelerator (linac) flattening filter enables a high rate of dose deposition with reduced treatment time. When used for megavoltage imaging, an unflat beam has reduced primary beam scatter resulting in sharper images. In fluoroscopic imaging mode, the unflat beam has higher photon count per image frame yielding higher contrast-to-noise ratio. The authors’ goal was to quantify the effects of an unflat beam on the image quality of megavoltage portal and fluoroscopic images.Methods: 6 MV projection images were acquired in fluoroscopic and portal modes using an electronic flat-panel imager. The effects of the flattening filter on the relative modulation transfer function (MTF) and contrast-to-noise ratio were quantified using the QC3 phantom. The impact of FF removal on the contrast-to-noise ratio of gold fiducial markers also was studied under various scatter conditions.Results: The unflat beam had improved contrast resolution, up to 40% increase in MTF contrast at the highest frequency measured (0.75 line pairs/mm). The contrast-to-noise ratio was increased as expected from the increased photon flux. The visualization of fiducial markers was markedly better using the unflat beam under all scatter conditions, enabling visualization of thin gold fiducial markers, the thinnest of which was not visible using the unflat beam.Conclusions: The removal of the flattening filter from a clinical linac leads to quantifiable improvements in the image quality of megavoltage projection images. These gains enable observers to more easily visualize thin fiducial markers and track their motion on fluoroscopic images.

  17. Value of computer analysis of exercise thallium images in the noninvasive detection of coronary artery disease

    SciTech Connect

    Kaul, S.; Newell, J.B.; Chesler, D.A.; Pohost, G.M.; Okada, R.D.; Guiney, T.E.; Boucher, C.A.

    1986-01-01

    An analysis was made of 196 patients with no previous myocardial infarction who had undergone thallium imaging with exercise and cardiac catheterization. Patients with a prior myocardial infarction were excluded, because in such situations the presence of CAD is already virtually certain. The aim was to determine the diagnostic value of computer-analyzed thallium imaging with exercise compared with the clinical and electrocardiographic assessment and analysis of visual images. To determine what variables correlated best with CAD, all were compared using stepwise analysis of logistic regression. This study provided an equation for calculating the probability of CAD. Data indicate that the major value of combining variable with statistical modeling was the optimization of specificity. The dominant variable was the number of initial quantitated defects with thallium. Clearance and redistribution were not needed in part because of the high quality of the method of quantification and in part because of selection of patients. The model permits the high sensitivity of this variable to be maintained but eliminates false-positive results in 15% of the patients with no CAD by using non-imaging variables available to the clinician (sex, peak cardiac rate, and the response of the ST segment during exercise).

  18. Image quality testing of assembled IR camera modules

    NASA Astrophysics Data System (ADS)

    Winters, Daniel; Erichsen, Patrik

    2013-10-01

    Infrared (IR) camera modules for the LWIR (8-12_m) that combine IR imaging optics with microbolometer focal plane array (FPA) sensors with readout electronics are becoming more and more a mass market product. At the same time, steady improvements in sensor resolution in the higher priced markets raise the requirement for imaging performance of objectives and the proper alignment between objective and FPA. This puts pressure on camera manufacturers and system integrators to assess the image quality of finished camera modules in a cost-efficient and automated way for quality control or during end-of-line testing. In this paper we present recent development work done in the field of image quality testing of IR camera modules. This technology provides a wealth of additional information in contrast to the more traditional test methods like minimum resolvable temperature difference (MRTD) which give only a subjective overall test result. Parameters that can be measured are image quality via the modulation transfer function (MTF) for broadband or with various bandpass filters on- and off-axis and optical parameters like e.g. effective focal length (EFL) and distortion. If the camera module allows for refocusing the optics, additional parameters like best focus plane, image plane tilt, auto-focus quality, chief ray angle etc. can be characterized. Additionally, the homogeneity and response of the sensor with the optics can be characterized in order to calculate the appropriate tables for non-uniformity correction (NUC). The technology can also be used to control active alignment methods during mechanical assembly of optics to high resolution sensors. Other important points that are discussed are the flexibility of the technology to test IR modules with different form factors, electrical interfaces and last but not least the suitability for fully automated measurements in mass production.

  19. Thematic Mapper image quality - Registration, noise, and resolution

    NASA Technical Reports Server (NTRS)

    Wrigley, R. C.; Card, D. H.; Hlavka, C. A.; Hall, J. R.; Mertz, F. C.; Archwamety, C.; Schowengerdt, R. A.

    1984-01-01

    The Landsat-4 satellite has two new imaging radiometers, including the redesigned Multispectral Scanner (MSS) and the Thematic Mapper (TM). The present investigation is concerned with an assessment of TM image quality on the basis of a study of band-to-band registration, periodic noise, and spatial resolution. In the TM images analyzed, the band-to-band registration accuracy of the instrument is very good. A few imperfections were found. Once a stable misregistration is removed, the TM should also meet its registration specifications between focal planes. Spatial resolution analyses in terms of MTF were performed in comparison modes. The forward and backward scans were shown to have virtually identical MTFs.

  20. Pyramid wavefront sensor for image quality evaluation of optical system

    NASA Astrophysics Data System (ADS)

    Chen, Zhendong

    2015-08-01

    When the pyramid wavefront sensor is used to evaluate the imaging quality, placed at the focal plane of the aberrated optical system e.g., a telescope, it splits the light into four beams. Four images of the pupil are created on the detector and the detection signals of the pyramid wavefront sensor are calculated with these four intensity patterns, providing information on the derivatives of the aberrated wavefront. Based on the theory of the pyramid wavefront sensor, we are going to develop simulation software and a wavefront detector which can be used to test the imaging quality of the telescope. In our system, the subpupil image intensity through the pyramid sensor is calculated to obtain the aberration of wavefront where the piston, tilt, defocus, spherical, coma, astigmatism and other high level aberrations are separately represented by Zernike polynomials. The imaging quality of the optical system is then evaluated by the subsequent wavefront reconstruction. The performance of our system is to be checked by comparing with the measurements carried out using Puntino wavefront instrument (the method of SH wavefront sensor). Within this framework, the measurement precision of pyramid sensor will be discussed as well through detailed experiments. In general, this project would be very helpful both in our understanding of the principle of the wavefront reconstruction and its future technical applications. So far, we have produced the pyramid and established the laboratory setup of the image quality detecting system based on this wavefront sensor. Preliminary results are obtained, in that we have obtained the intensity images of the four pupils. Additional work is needed to analyze the characteristics of the pyramid wavefront sensor.

  1. Simultaneous Analysis and Quality Assurance for Diffusion Tensor Imaging

    PubMed Central

    Lauzon, Carolyn B.; Asman, Andrew J.; Esparza, Michael L.; Burns, Scott S.; Fan, Qiuyun; Gao, Yurui; Anderson, Adam W.; Davis, Nicole; Cutting, Laurie E.; Landman, Bennett A.

    2013-01-01

    Diffusion tensor imaging (DTI) enables non-invasive, cyto-architectural mapping of in vivo tissue microarchitecture through voxel-wise mathematical modeling of multiple magnetic resonance imaging (MRI) acquisitions, each differently sensitized to water diffusion. DTI computations are fundamentally estimation processes and are sensitive to noise and artifacts. Despite widespread adoption in the neuroimaging community, maintaining consistent DTI data quality remains challenging given the propensity for patient motion, artifacts associated with fast imaging techniques, and the possibility of hardware changes/failures. Furthermore, the quantity of data acquired per voxel, the non-linear estimation process, and numerous potential use cases complicate traditional visual data inspection approaches. Currently, quality inspection of DTI data has relied on visual inspection and individual processing in DTI analysis software programs (e.g. DTIPrep, DTI-studio). However, recent advances in applied statistical methods have yielded several different metrics to assess noise level, artifact propensity, quality of tensor fit, variance of estimated measures, and bias in estimated measures. To date, these metrics have been largely studied in isolation. Herein, we select complementary metrics for integration into an automatic DTI analysis and quality assurance pipeline. The pipeline completes in 24 hours, stores statistical outputs, and produces a graphical summary quality analysis (QA) report. We assess the utility of this streamlined approach for empirical quality assessment on 608 DTI datasets from pediatric neuroimaging studies. The efficiency and accuracy of quality analysis using the proposed pipeline is compared with quality analysis based on visual inspection. The unified pipeline is found to save a statistically significant amount of time (over 70%) while improving the consistency of QA between a DTI expert and a pool of research associates. Projection of QA metrics to a low dimensional manifold reveal qualitative, but clear, QA-study associations and suggest that automated outlier/anomaly detection would be feasible. PMID:23637895

  2. Quality of traffic flow on urban arterial streets and its relationship with safety.

    PubMed

    Dixit, Vinayak V; Pande, Anurag; Abdel-Aty, Mohamed; Das, Abhishek; Radwan, Essam

    2011-09-01

    The two-fluid model for vehicular traffic flow explains the traffic on arterials as a mix of stopped and running vehicles. It describes the relationship between the vehicles' running speed and the fraction of running vehicles. The two parameters of the model essentially represent 'free flow' travel time and level of interaction among vehicles, and may be used to evaluate urban roadway networks and urban corridors with partially limited access. These parameters are influenced by not only the roadway characteristics but also by behavioral aspects of driver population, e.g., aggressiveness. Two-fluid models are estimated for eight arterial corridors in Orlando, FL for this study. The parameters of the two-fluid model were used to evaluate corridor level operations and the correlations of these parameters' with rates of crashes having different types/severity. Significant correlations were found between two-fluid parameters and rear-end and angle crash rates. Rate of severe crashes was also found to be significantly correlated with the model parameter signifying inter-vehicle interactions. While there is need for further analysis, the findings suggest that the two-fluid model parameters may have potential as surrogate measures for traffic safety on urban arterial streets. PMID:21658486

  3. Color image encryption using a high-quality elemental image array

    NASA Astrophysics Data System (ADS)

    Li, Xiao-Wei; Kim, Seok-Tae; Lee, In-Kwon

    2014-12-01

    In this paper, we present a color image encoding algorithm by combined use of the high-quality elemental image array (EIA) and the pseudo-random mask. To overcome low resolution drawbacks in widely used optical pickup system, in our scheme, the pseudo-inverse filter is introduced to improve this problem. In the cryptosystem, the proposed scheme provides high security because of the high key space of cellular automata. Meanwhile, the hologram-like attribute of the EIA can significantly improve the robustness of the encrypted image against some common image processing attacks. Experiments and analysis have both demonstrated the feasibility and efficiency of the image encryption algorithm.

  4. Image quality, space-qualified UV interference filters

    NASA Technical Reports Server (NTRS)

    Mooney, Thomas A.

    1992-01-01

    The progress during the contract period is described. The project involved fabrication of image quality, space-qualified bandpass filters in the 200-350 nm spectral region. Ion-assisted deposition (IAD) was applied to produce stable, reasonably durable filter coatings on space compatible UV substrates. Thin film materials and UV transmitting substrates were tested for resistance to simulated space effects.

  5. Comparison of retinal image quality with spherical and customized aspheric

    E-print Network

    Dainty, Chris

    retinal image quality, despite the misalignments that accompany cataract surgery. To test this hypothesis aspheric intraocular lenses calculated with real ray tracing," J. Cataract Refract. Surg. 35(11), 1984 in cataract patients," J. Cataract Refract. Surg. 26(7), 1022­1027 (2000). 10. J. Aramberri, "Intraocular lens

  6. Aberrations and retinal image quality of the normal human eye

    E-print Network

    Aberrations and retinal image quality of the normal human eye Junzhong Liang and David R. Williams important optical instrument is the human eye, yet its optical performance has not been completely char to measure the irregular as well as the classical aberrations of the eye, providing a more complete

  7. Mammography in New Zealand: radiation dose and image quality.

    PubMed

    Poletti, J L; Williamson, B D; Mitchell, A W

    1991-06-01

    The mean glandular doses to the breast, image quality and machine performance have been determined for all mammographic x-ray facilities in New Zealand, during 1988-89. For 30 mm and 45 mm phantoms the mean doses per film were 1.03 +/- 0.56 mGy and 1.97 +/- 1.06 mGy. These doses are within international guide-lines. Image quality (detection of simulated microcalcifications, and contrast-detail performance) was found to depend on focal spot size/FFD combination, breast thickness, and film processing. The best machines could resolve 0.2 mm aluminium oxide specks with the contact technique. The use of a grid improved image quality as did magnification. Extended cycle film processing reduced doses, but the claimed improvement in image quality was not apparent from our data. The machine calibration parameters kVp, HVL and timer accuracy were in general within accepted tolerances. Automatic exposure controls in some cases gave poor control of film density with changing breast thickness. PMID:1747087

  8. Perceived interest versus overt visual attention in image quality assessment

    NASA Astrophysics Data System (ADS)

    Engelke, Ulrich; Zhang, Wei; Le Callet, Patrick; Liu, Hantao

    2015-03-01

    We investigate the impact of overt visual attention and perceived interest on the prediction performance of image quality metrics. Towards this end we performed two respective experiments to capture these mechanisms: an eye gaze tracking experiment and a region-of-interest selection experiment. Perceptual relevance maps were created from both experiments and integrated into the design of the image quality metrics. Correlation analysis shows that indeed there is an added value of integrating these perceptual relevance maps. We reveal that the improvement in prediction accuracy is not statistically different between fixation density maps from eye gaze tracking data and region-of-interest maps, thus, indicating the robustness of different perceptual relevance maps for the performance gain of image quality metrics. Interestingly, however, we found that thresholding of region-of-interest maps into binary maps significantly deteriorates prediction performance gain for image quality metrics. We provide a detailed analysis and discussion of the results as well as the conceptual and methodological differences between capturing overt visual attention and perceived interest.

  9. Noise Brush: Interactive High Quality Image-Noise Separation Chi-Keung Tang

    E-print Network

    Wang, Jue

    Noise Brush: Interactive High Quality Image-Noise Separation Jia Chen Chi-Keung Tang The Hong the user with a set of easy interactive control to achieve high quality image-noise separation shown in (c an interactive approach using joint image- noise filtering for achieving high quality image-noise separation

  10. Comparison of quality control software tools for diffusion tensor imaging.

    PubMed

    Liu, Bilan; Zhu, Tong; Zhong, Jianhui

    2015-04-01

    Image quality of diffusion tensor imaging (DTI) is critical for image interpretation, diagnostic accuracy and efficiency. However, DTI is susceptible to numerous detrimental artifacts that may impair the reliability and validity of the obtained data. Although many quality control (QC) software tools are being developed and are widely used and each has its different tradeoffs, there is still no general agreement on an image quality control routine for DTIs, and the practical impact of these tradeoffs is not well studied. An objective comparison that identifies the pros and cons of each of the QC tools will be helpful for the users to make the best choice among tools for specific DTI applications. This study aims to quantitatively compare the effectiveness of three popular QC tools including DTI studio (Johns Hopkins University), DTIprep (University of North Carolina at Chapel Hill, University of Iowa and University of Utah) and TORTOISE (National Institute of Health). Both synthetic and in vivo human brain data were used to quantify adverse effects of major DTI artifacts to tensor calculation as well as the effectiveness of different QC tools in identifying and correcting these artifacts. The technical basis of each tool was discussed, and the ways in which particular techniques affect the output of each of the tools were analyzed. The different functions and I/O formats that three QC tools provide for building a general DTI processing pipeline and integration with other popular image processing tools were also discussed. PMID:25460331

  11. Pilot model of the extrahigh-quality imaging system

    NASA Astrophysics Data System (ADS)

    Taniho, Shuji; Ito, Hiroshi; Moriwaki, Hirohumi; Katada, Hideo; Makino, Shiro

    1996-02-01

    The progress of computer graphics and display technology has led us to always obtain an advanced visual image. However, we now feel the limit of the color reproduction (by the present 24 bits/pixel quantization, R, G, B, 8 bits respectively,) when pursuing a higher image quality. Therefore, we are developing an 'extra high quality imaging system' of 36 bit/pixel quantization (R, G, B, 12 bits, respectively.) This system comprises a MO disk drive, a controlling computer, a frame buffer and two 21' displays. The 2048 multiplied by 2048 pixel (36 bits/pixel) image data are read from the MO disk drive, and are sent to the frame buffer. A deliberately constructed 16 M byte frame buffer outputs the 36 bits/pixel video signal at a 200 MHz clock rate. Two displays, using a shadow-mask type CRT, are driven at a 78.7 kHz horizontal frequency. The system outputs the 36 bits/pixel and the 24 bits/pixel video signals concurrently, which makes it possible to compare the image quality of a 36 bits/pixel system with that of a 24 bits/pixel system. Many characteristics and physical factors, including noise, which do not cause a serious problem in conventional 24 bits/pixel systems, have a much more serious effect on the 36 bits/pixel system. We have now obtained the performance of color depth of up to 33 bits/pixel.

  12. Structural similarity analysis for brain MR image quality assessment

    NASA Astrophysics Data System (ADS)

    Punga, Mirela Visan; Moldovanu, Simona; Moraru, Luminita

    2014-11-01

    Brain MR images are affected and distorted by various artifacts as noise, blur, blotching, down sampling or compression and as well by inhomogeneity. Usually, the performance of pre-processing operation is quantified by using the quality metrics as mean squared error and its related metrics such as peak signal to noise ratio, root mean squared error and signal to noise ratio. The main drawback of these metrics is that they fail to take the structural fidelity of the image into account. For this reason, we addressed to investigate the structural changes related to the luminance and contrast variation (as non-structural distortions) and to denoising process (as structural distortion)through an alternative metric based on structural changes in order to obtain the best image quality.

  13. Association between Poor Glycemic Control, Impaired Sleep Quality, and Increased Arterial Thickening in Type 2 Diabetic Patients

    PubMed Central

    Yoda, Koichiro; Inaba, Masaaki; Hamamoto, Kae; Yoda, Maki; Tsuda, Akihiro; Mori, Katsuhito; Imanishi, Yasuo; Emoto, Masanori; Yamada, Shinsuke

    2015-01-01

    Objective Poor sleep quality is an independent predictor of cardiovascular events. However, little is known about the association between glycemic control and objective sleep architecture and its influence on arteriosclerosis in patients with type-2 diabetes mellitus (DM). The present study examined the association of objective sleep architecture with both glycemic control and arteriosclerosis in type-2 DM patients. Design Cross-sectional study in vascular laboratory. Methods The subjects were 63 type-2 DM inpatients (M/F, 32/31; age, 57.5±13.1) without taking any sleeping promoting drug and chronic kidney disease. We examined objective sleep architecture by single-channel electroencephalography and arteriosclerosis by carotid-artery intima-media thickness (CA-IMT). Results HbA1c was associated significantly in a negative manner with REM sleep latency (interval between sleep-onset and the first REM period) (?=-0.280, p=0.033), but not with other measurements of sleep quality. REM sleep latency associated significantly in a positive manner with log delta power (the marker of deep sleep) during that period (?=0.544, p=0.001). In the model including variables univariately correlated with CA-IMT (REM sleep latency, age, DM duration, systolic blood pressure, and HbA1c) as independent variables, REM sleep latency (?=-0.232, p=0.038), but not HbA1c were significantly associated with CA-IMT. When log delta power was included in place of REM sleep latency, log delta power (?=-0.257, p=0.023) emerged as a significant factor associated with CA-IMT. Conclusions In type-2 DM patients, poor glycemic control was independently associated with poor quality of sleep as represented by decrease of REM sleep latency which might be responsible for increased CA-IMT, a relevant marker for arterial wall thickening. PMID:25875738

  14. Imaging through turbid media via sparse representation: imaging quality comparison of three projection matrices

    NASA Astrophysics Data System (ADS)

    Shao, Xiaopeng; Li, Huijuan; Wu, Tengfei; Dai, Weijia; Bi, Xiangli

    2015-05-01

    The incident light will be scattered away due to the inhomogeneity of the refractive index in many materials which will greatly reduce the imaging depth and degrade the imaging quality. Many exciting methods have been presented in recent years for solving this problem and realizing imaging through a highly scattering medium, such as the wavefront modulation technique and reconstruction technique. The imaging method based on compressed sensing (CS) theory can decrease the computational complexity because it doesn't require the whole speckle pattern to realize reconstruction. One of the key premises of this method is that the object is sparse or can be sparse representation. However, choosing a proper projection matrix is very important to the imaging quality. In this paper, we analyzed that the transmission matrix (TM) of a scattering medium obeys circular Gaussian distribution, which makes it possible that a scattering medium can be used as the measurement matrix in the CS theory. In order to verify the performance of this method, a whole optical system is simulated. Various projection matrices are introduced to make the object sparse, including the fast Fourier transform (FFT) basis, the discrete cosine transform (DCT) basis and the discrete wavelet transform (DWT) basis, the imaging performances of each of which are compared comprehensively. Simulation results show that for most targets, applying the discrete wavelet transform basis will obtain an image in good quality. This work can be applied to biomedical imaging and used to develop real-time imaging through highly scattering media.

  15. A study of image quality for radar image processing. [synthetic aperture radar imagery

    NASA Technical Reports Server (NTRS)

    King, R. W.; Kaupp, V. H.; Waite, W. P.; Macdonald, H. C.

    1982-01-01

    Methods developed for image quality metrics are reviewed with focus on basic interpretation or recognition elements including: tone or color; shape; pattern; size; shadow; texture; site; association or context; and resolution. Seven metrics are believed to show promise as a way of characterizing the quality of an image: (1) the dynamic range of intensities in the displayed image; (2) the system signal-to-noise ratio; (3) the system spatial bandwidth or bandpass; (4) the system resolution or acutance; (5) the normalized-mean-square-error as a measure of geometric fidelity; (6) the perceptual mean square error; and (7) the radar threshold quality factor. Selective levels of degradation are being applied to simulated synthetic radar images to test the validity of these metrics.

  16. Septal myocardial perfusion imaging with thallium-201 in the diagnosis of proximal left anterior descending coronary artery disease

    SciTech Connect

    Pichard, A.D.; Wiener, I.; Martinez, E.; Horowitz, S.; Patterson, R.; Meller, J.; Goldsmith, S.J.; Gorlin, R.; Herman, M.V.

    1981-07-01

    The use of myocardial perfusion imaging (MPI) to identify obstructive coronary disease of the left anterior descending coronary artery proximal to the first septal perforator (prox LAD) was studied in 60 patients. Perfusion of the septum and anteroapical areas with thallium-201 injected during exercise was compared to results of coronary arteriography. Septal MPI defect was found in 92.3% of patients with obstruction of the proximal LAD, 27.7% of patients with obstruction of LAD distal to first septal perforator, 0% in patients with obstructions involving right or circumflex arteries, and in 10.5% of patients without coronary disease. Anteroapical MPI defects were found with similar frequency in the three groups with obstructive coronary disease. Septal MPI defect had a sensitivity of 92.3% and specificity of 85.4% in the diagnosis of proximal LAD disease. Normal septal perfusion with thallium-201 virtually excluded proximal LAD disease.

  17. Evaluation of Quality of Rice Grains by Photoacoustic Imaging

    NASA Astrophysics Data System (ADS)

    Suzuki, Manabu; Miyamoto, Katsuhiko; Hoshimiya, Tsutomu

    2005-06-01

    Recently, quality evaluation and control has become increasingly important in biology and agriculture. The evaluation of the quality of food plants has been performed by many inspection methods. To date, the evaluation of the grain of crops by photoacoustic spectroscopy in the infrared region has only been performed for corn. We have developed a method of applying a photoacoustic microscope (PAM) to pollen analysis. In this study, a PAM was used to evaluate the quality of crop grains, rice in this case, for the first time. Due to differences in the absorption of the laser beam, the homogeneity of rice grains was measured and shown as thermal images. The resolution was sufficiently good to evaluate a single grain of rice. This method has an advantage in that it can be used to measure the existence of both the surface and back surface colored regions. In addition to conventional video image evaluation or the macroscopic optical absorption method, PA imaging can enable the evaluation of the quality and condition of rice grains.

  18. Underwater image quality enhancement through composition of dual-intensity images and Rayleigh-stretching.

    PubMed

    Abdul Ghani, Ahmad Shahrizan; Mat Isa, Nor Ashidi

    2014-01-01

    The quality of underwater image is poor due to the properties of water and its impurities. The properties of water cause attenuation of light travels through the water medium, resulting in low contrast, blur, inhomogeneous lighting, and color diminishing of the underwater images. This paper proposes a method of enhancing the quality of underwater image. The proposed method consists of two stages. At the first stage, the contrast correction technique is applied to the image, where the image is applied with the modified Von Kries hypothesis and stretching the image into two different intensity images at the average value with respects to Rayleigh distribution. At the second stage, the color correction technique is applied to the image where the image is first converted into hue-saturation-value (HSV) color model. The modification of the color component increases the image color performance. Qualitative and quantitative analyses indicate that the proposed method outperforms other state-of-the-art methods in terms of contrast, details, and noise reduction. PMID:25674483

  19. Signal Quality Assessment of Retinal Optical Coherence Tomography Images

    PubMed Central

    Huang, Yijun; Gangaputra, Sapna; Lee, Kristine E.; Narkar, Ashwini R.; Klein, Ronald; Klein, Barbara E. K.; Meuer, Stacy M.; Danis, Ronald P.

    2012-01-01

    Purpose The purpose of this article was to assess signal quality of retinal optical coherence tomography (OCT) images from multiple devices using subjective and quantitative measurements. Methods A total of 120 multiframe OCT images from 4 spectral domain OCT devices (Cirrus, RTVue, Spectralis, and 3D OCT-1000) were evaluated subjectively by trained graders, and measured quantitatively using a derived parameter, maximum tissue contrast index (mTCI). An intensity histogram decomposition model was proposed to separate the foreground and background information of OCT images and to calculate the mTCI. The mTCI results were compared with the manufacturer signal index (MSI) provided by the respective devices, and to the subjective grading scores (SGS). Results Statistically significant correlations were observed between the paired methods (i.e., SGS and MSI, SGS and mTCI, and mTCI and MSI). Fisher's Z transformation indicated the Pearson correlation coefficient ? ? 0.8 for all devices. Using the Deming regression, correlation parameters between the paired methods were established. This allowed conversion from the proprietary MSI values to SGS and mTCI that are universally applied to each device. Conclusions The study suggests signal quality of retinal OCT images can be evaluated subjectively and objectively, independent of the devices. Together with the proposed histogram decomposition model, mTCI may be used as a standardization metric for OCT signal quality that would affect measurements. PMID:22427567

  20. Effects of task and image properties on visual-attention deployment in image-quality assessment

    NASA Astrophysics Data System (ADS)

    Alers, Hani; Redi, Judith; Liu, Hantao; Heynderickx, Ingrid

    2015-03-01

    It is important to understand how humans view images and how their behavior is affected by changes in the properties of the viewed images and the task they are given, particularly the task of scoring the image quality (IQ). This is a complex behavior that holds great importance for the field of image-quality research. This work builds upon 4 years of research work spanning three databases studying image-viewing behavior. Using eye-tracking equipment, it was possible to collect information on human viewing behavior of different kinds of stimuli and under different experimental settings. This work performs a cross-analysis on the results from all these databases using state-of-the-art similarity measures. The results strongly show that asking the viewers to score the IQ significantly changes their viewing behavior. Also muting the color saturation seems to affect the saliency of the images. However, a change in IQ was not consistently found to modify visual attention deployment, neither under free looking nor during scoring. These results are helpful in gaining a better understanding of image viewing behavior under different conditions. They also have important implications on work that collects subjective image-quality scores from human observers.

  1. Reducing the absorbed dose in analogue radiography of infant chest images by improving the image quality, using image processing techniques.

    TOXLINE Toxicology Bibliographic Information

    Karimian A; Yazdani S; Askari MA

    2011-09-01

    Radiographic inspection is one of the most widely employed techniques for medical testing methods. Because of poor contrast and high un-sharpness of radiographic image quality in films, converting radiographs to a digital format and using further digital image processing is the best method of enhancing the image quality and assisting the interpreter in their evaluation. In this research work, radiographic films of 70 infant chest images with different sizes of defects were selected. To digitise the chest images and employ image processing the two algorithms (i) spatial domain and (ii) frequency domain techniques were used. The MATLAB environment was selected for processing in the digital format. Our results showed that by using these two techniques, the defects with small dimensions are detectable. Therefore, these suggested techniques may help medical specialists to diagnose the defects in the primary stages and help to prevent more repeat X-ray examination of paediatric patients.

  2. TL dosimetry for quality control of CR mammography imaging systems

    NASA Astrophysics Data System (ADS)

    Gaona, E.; Nieto, J. A.; Góngora, J. A. I. D.; Arreola, M.; Enríquez, J. G. F.

    The aim of this work is to estimate the average glandular dose with thermoluminescent (TL) dosimetry and comparison with quality imaging in computed radiography (CR) mammography. For a measuring dose, the Food and Drug Administration (FDA) and the American College of Radiology (ACR) use a phantom, so that dose and image quality are assessed with the same test object. The mammography is a radiological image to visualize early biological manifestations of breast cancer. Digital systems have two types of image-capturing devices, full field digital mammography (FFDM) and CR mammography. In Mexico, there are several CR mammography systems in clinical use, but only one system has been approved for use by the FDA. Mammography CR uses a photostimulable phosphor detector (PSP) system. Most CR plates are made of 85% BaFBr and 15% BaFI doped with europium (Eu) commonly called barium flourohalideE We carry out an exploratory survey of six CR mammography units from three different manufacturers and six dedicated X-ray mammography units with fully automatic exposure. The results show three CR mammography units (50%) have a dose greater than 3.0 mGy without demonstrating improved image quality. The differences between doses averages from TLD system and dosimeter with ionization chamber are less than 10%. TLD system is a good option for average glandular dose measurement for X-rays with a HVL (0.35-0.38 mmAl) and kVp (24-26) used in quality control procedures with ACR Mammography Accreditation Phantom.

  3. Image-Processing Techniques for the Creation of Presentation-Quality Astronomical Images

    E-print Network

    T. A. Rector; Z. G. Levay; L. M. Frattare; J. English; K. Pu'uohau-Pummill

    2004-12-06

    The quality of modern astronomical data, the power of modern computers and the agility of current image-processing software enable the creation of high-quality images in a purely digital form. The combination of these technological advancements has created a new ability to make color astronomical images. And in many ways it has led to a new philosophy towards how to create them. A practical guide is presented on how to generate astronomical images from research data with powerful image-processing programs. These programs use a layering metaphor that allows for an unlimited number of astronomical datasets to be combined in any desired color scheme, creating an immense parameter space to be explored using an iterative approach. Several examples of image creation are presented. A philosophy is also presented on how to use color and composition to create images that simultaneously highlight scientific detail and are aesthetically appealing. This philosophy is necessary because most datasets do not correspond to the wavelength range of sensitivity of the human eye. The use of visual grammar, defined as the elements which affect the interpretation of an image, can maximize the richness and detail in an image while maintaining scientific accuracy. By properly using visual grammar, one can imply qualities that a two-dimensional image intrinsically cannot show, such as depth, motion and energy. In addition, composition can be used to engage viewers and keep them interested for a longer period of time. The use of these techniques can result in a striking image that will effectively convey the science within the image, to scientists and to the public.

  4. Image Quality Analysis of Various Gastrointestinal Endoscopes: Why Image Quality Is a Prerequisite for Proper Diagnostic and Therapeutic Endoscopy

    PubMed Central

    Ko, Weon Jin; An, Pyeong; Ko, Kwang Hyun; Hahm, Ki Baik; Hong, Sung Pyo

    2015-01-01

    Arising from human curiosity in terms of the desire to look within the human body, endoscopy has undergone significant advances in modern medicine. Direct visualization of the gastrointestinal (GI) tract by traditional endoscopy was first introduced over 50 years ago, after which fairly rapid advancement from rigid esophagogastric scopes to flexible scopes and high definition videoscopes has occurred. In an effort towards early detection of precancerous lesions in the GI tract, several high-technology imaging scopes have been developed, including narrow band imaging, autofocus imaging, magnified endoscopy, and confocal microendoscopy. However, these modern developments have resulted in fundamental imaging technology being skewed towards red-green-blue and this technology has obscured the advantages of other endoscope techniques. In this review article, we have described the importance of image quality analysis using a survey to consider the diversity of endoscope system selection in order to better achieve diagnostic and therapeutic goals. The ultimate aims can be achieved through the adoption of modern endoscopy systems that obtain high image quality. PMID:26473119

  5. Image Quality Analysis of Various Gastrointestinal Endoscopes: Why Image Quality Is a Prerequisite for Proper Diagnostic and Therapeutic Endoscopy.

    PubMed

    Ko, Weon Jin; An, Pyeong; Ko, Kwang Hyun; Hahm, Ki Baik; Hong, Sung Pyo; Cho, Joo Young

    2015-09-01

    Arising from human curiosity in terms of the desire to look within the human body, endoscopy has undergone significant advances in modern medicine. Direct visualization of the gastrointestinal (GI) tract by traditional endoscopy was first introduced over 50 years ago, after which fairly rapid advancement from rigid esophagogastric scopes to flexible scopes and high definition videoscopes has occurred. In an effort towards early detection of precancerous lesions in the GI tract, several high-technology imaging scopes have been developed, including narrow band imaging, autofocus imaging, magnified endoscopy, and confocal microendoscopy. However, these modern developments have resulted in fundamental imaging technology being skewed towards red-green-blue and this technology has obscured the advantages of other endoscope techniques. In this review article, we have described the importance of image quality analysis using a survey to consider the diversity of endoscope system selection in order to better achieve diagnostic and therapeutic goals. The ultimate aims can be achieved through the adoption of modern endoscopy systems that obtain high image quality. PMID:26473119

  6. How much image noise can be added in cardiac x-ray imaging without loss in perceived image quality?

    NASA Astrophysics Data System (ADS)

    Gislason-Lee, Amber J.; Kumcu, Asli; Kengyelics, Stephen M.; Rhodes, Laura A.; Davies, Andrew G.

    2015-03-01

    Dynamic X-ray imaging systems are used for interventional cardiac procedures to treat coronary heart disease. X-ray settings are controlled automatically by specially-designed X-ray dose control mechanisms whose role is to ensure an adequate level of image quality is maintained with an acceptable radiation dose to the patient. Current commonplace dose control designs quantify image quality by performing a simple technical measurement directly from the image. However, the utility of cardiac X-ray images is in their interpretation by a cardiologist during an interventional procedure, rather than in a technical measurement. With the long term goal of devising a clinically-relevant image quality metric for an intelligent dose control system, we aim to investigate the relationship of image noise with clinical professionals' perception of dynamic image sequences. Computer-generated noise was added, in incremental amounts, to angiograms of five different patients selected to represent the range of adult cardiac patient sizes. A two alternative forced choice staircase experiment was used to determine the amount of noise which can be added to a patient image sequences without changing image quality as perceived by clinical professionals. Twenty-five viewing sessions (five for each patient) were completed by thirteen observers. Results demonstrated scope to increase the noise of cardiac X-ray images by up to 21% +/- 8% before it is noticeable by clinical professionals. This indicates a potential for 21% radiation dose reduction since X-ray image noise and radiation dose are directly related; this would be beneficial to both patients and personnel.

  7. IEEE TRANSACTIONS ON IMAGE PROCESSING, VOL. 14, NO. 12, DECEMBER 2005 2117 An Information Fidelity Criterion for Image Quality

    E-print Network

    de Veciana, Gustavo

    of quality assessment (QA) research is to design algo- rithms that can automatically assess the quality of quality assessment (QA) research is, therefore, to design algorithms for objective evaluation of quality Criterion for Image Quality Assessment Using Natural Scene Statistics Hamid Rahim Sheikh, Member, IEEE, Alan

  8. Performance evaluation of objective quality metrics for HDR image compression

    NASA Astrophysics Data System (ADS)

    Valenzise, Giuseppe; De Simone, Francesca; Lauga, Paul; Dufaux, Frederic

    2014-09-01

    Due to the much larger luminance and contrast characteristics of high dynamic range (HDR) images, well-known objective quality metrics, widely used for the assessment of low dynamic range (LDR) content, cannot be directly applied to HDR images in order to predict their perceptual fidelity. To overcome this limitation, advanced fidelity metrics, such as the HDR-VDP, have been proposed to accurately predict visually significant differences. However, their complex calibration may make them difficult to use in practice. A simpler approach consists in computing arithmetic or structural fidelity metrics, such as PSNR and SSIM, on perceptually encoded luminance values but the performance of quality prediction in this case has not been clearly studied. In this paper, we aim at providing a better comprehension of the limits and the potentialities of this approach, by means of a subjective study. We compare the performance of HDR-VDP to that of PSNR and SSIM computed on perceptually encoded luminance values, when considering compressed HDR images. Our results show that these simpler metrics can be effectively employed to assess image fidelity for applications such as HDR image compression.

  9. Clinical study in phase- contrast mammography: image-quality analysis.

    PubMed

    Longo, Renata; Tonutti, Maura; Rigon, Luigi; Arfelli, Fulvia; Dreossi, Diego; Quai, Elisa; Zanconati, Fabrizio; Castelli, Edoardo; Tromba, Giuliana; Cova, Maria A

    2014-03-01

    The first clinical study of phase-contrast mammography (PCM) with synchrotron radiation was carried out at the Synchrotron Radiation for Medical Physics beamline of the Elettra synchrotron radiation facility in Trieste (Italy) in 2006-2009. The study involved 71 patients with unresolved breast abnormalities after conventional digital mammography and ultrasonography exams carried out at the Radiology Department of Trieste University Hospital. These cases were referred for mammography at the synchrotron radiation facility, with images acquired using a propagation-based phase-contrast imaging technique. To investigate the contribution of phase-contrast effects to the image quality, two experienced radiologists specialized in mammography assessed the visibility of breast abnormalities and of breast glandular structures. The images acquired at the hospital and at the synchrotron radiation facility were compared and graded according to a relative seven-grade visual scoring system. The statistical analysis highlighted that PCM with synchrotron radiation depicts normal structures and abnormal findings with higher image quality with respect to conventional digital mammography. PMID:24470410

  10. Loss of image quality in photobleaching during microscopic imaging of fluorescent probes bound to chromatin.

    PubMed

    Bernas, Tytus; Robinson, J Paul; Asem, Elikplimi K; Rajwa, Bartek

    2005-01-01

    Prolonged excitation of fluorescent probes leads eventually to loss of their capacity to emit light. A decrease in the number of detected photons reduces subsequently the resolving power of a fluorescence microscope. Adverse effects of fluorescence intensity loss on the quality of microscopic images of biological specimens have been recognized, but not determined quantitatively. We propose three human-independent methods of quality determination. These techniques require no reference images and are based on calculation of the actual resolution distance, information entropy, and signal-to-noise ratio (SNR). We apply the three measures to study the effect of photobleaching in cell nuclei stained with propidium iodide (PI) and chromomycin A3 (CA3) and imaged with fluorescence confocal microscopy. We conclude that the relative loss of image quality is smaller than the corresponding decrease in fluorescence intensity. Furthermore, the extent of quality loss is related to the optical properties of the imaging system and the noise characteristics of the detector. We discuss the importance of these findings for optimal registration and compression of biological images. PMID:16409080

  11. DES exposure checker: Dark Energy Survey image quality control crowdsourcer

    NASA Astrophysics Data System (ADS)

    Melchior, Peter; Sheldon, Erin; Drlica-Wagner, Alex; Rykoff, Eli S.

    2015-11-01

    DES exposure checker renders science-grade images directly to a web browser and allows users to mark problematic features from a set of predefined classes, thus allowing image quality control for the Dark Energy Survey to be crowdsourced through its web application. Users can also generate custom labels to help identify previously unknown problem classes; generated reports are fed back to hardware and software experts to help mitigate and eliminate recognized issues. These problem reports allow rapid correction of artifacts that otherwise may be too subtle or infrequent to be recognized.

  12. Multispectral fluorescence lifetime imaging system for intravascular diagnostics with ultrasound guidance: in vivo validation in swine arteries

    PubMed Central

    Bec, Julien; Ma, Dinglong M.; Yankelevich, Diego R.; Liu, Jing; Ferrier, William T.; Southard, Jeffrey; Marcu, Laura

    2015-01-01

    Fluorescence lifetime technique has demonstrated potential for analysis of atherosclerotic lesions and for complementing existing intravascular imaging modalities such as intravascular ultrasound (IVUS) in identifying lesions at high risk of rupture. This study presents a multimodal catheter system integrating a 40 MHz commercial IVUS and fluorescence lifetime imaging (FLIm) using fast helical motion scanning (400 rpm, 0.75 mm/s), able to acquire in vivo in pulsatile blood flow the autofluorescence emission of arterial vessels with high precision (5.08 ± 0.26 ns mean average lifetime over 13 scans). Co-registered FLIm and IVUS data allowed 3D visualization of both biochemical and morphological vessel properties. Current study supports the development of clinically compatible intravascular diagnostic system integrating FLIm and demonstrates, to our knowledge, the first in vivo intravascular application of a fluorescence lifetime imaging technique. PMID:23495014

  13. 256-slice CT coronary angiography in atrial fibrillation: The impact of mean heart rate and heart rate variability on image quality

    NASA Astrophysics Data System (ADS)

    Chen, Liang-Kuang; Hsu, Shih-Ming; Mok, Greta S. P.; Law, Wei-Yip; Lu, Kun-Mu; Yang, Ching-Ching; Wu, Tung-Hsin

    2011-08-01

    The aim of this study was to evaluate the image quality of 256-MDCT in atrial fibrillation and to compare the findings with those among patients in sinus rhythm.MaterialsAll reconstructed images were evaluated by two independent experienced readers blinded to patient information, heart rate, and ECG results to assess the diagnostic quality of images of the coronary artery segments using axial images, multi-planar reformations, maximum intensity projections, and volume rendering technique.ResultsNo statistical significance was detected in terms of the overall image quality between patients in sinus rhythm and with atrial fibrillation. Pearson's correlation analysis showed no significant association between image quality and mean heart rate no matter for patients in sinus rhythm or with atrial fibrillation. Similarly, there was no correlation between image quality and heart rate variability for either patients in sinus rhythm or with atrial fibrillation. Our results showed that the optimal reconstruction window depends on patient's HR, and the pattern for patients in atrial fibrillation is similar to that obtained from non-atrial fibrillation patients.ConclusionThis study shows the potential of using 256-MDCT coronary angiography in patients with atrial fibrillation. Our results suggest that when appropriate reconstruction timing window is applied, patients with atrial fibrillation do not have to be excluded from MDCT coronary angiographic examinations.

  14. Balancing Image Quality and Compression Factor for Special Stains Whole Slide Images

    PubMed Central

    Sharma, Anurag; Bautista, Pinky; Yagi, Yukako

    2012-01-01

    The objective is to find a practical balance between quality and performance for daily high volume whole slide imaging. We evaluated whole slide images created by various scanners at different compression factors to determine the best suitable quality factor (QF) needed for pathological images of special stains. Method: We scanned two sets of eight special stains slides each at 0.50 ?m/pixel resolution in Hamamatsu scanner at six and five QF levels respectively to generate 72 images which were observed at a calibrated monitor by imaging specialists, a histo-technician, and a pathologist to find the most suitable QF level for special stains in digital slides. Results: Most special stains images were acceptable at QF 30 except for the stain Reticulin where the lowest acceptable QF was 50. The compression of images from QF 90 to QF 50 reduced the size of the images by 62.73%. Conclusion: 0.50 ?m/pixel images at QF 50 or above were found suitable 12 special stain. PMID:21987586

  15. Segmentation of the lumen and media-adventitia boundaries of the common carotid artery from 3D ultrasound images

    NASA Astrophysics Data System (ADS)

    Ukwatta, E.; Awad, J.; Ward, A. D.; Samarabandu, J.; Krasinski, A.; Parraga, G.; Fenster, A.

    2011-03-01

    Three-dimensional ultrasound (3D US) vessel wall volume (VWV) measurements provide high measurement sensitivity and reproducibility for the monitoring and assessment of carotid atherosclerosis. In this paper, we describe a semiautomated approach based on the level set method to delineate the media-adventitia and lumen boundaries of the common carotid artery from 3D US images to support the computation of VWV. Due to the presence of plaque and US image artifacts, the carotid arteries are challenging to segment using image information alone. Our segmentation framework combines several image cues with domain knowledge and limited user interaction. Our method was evaluated with respect to manually outlined boundaries on 430 2D US images extracted from 3D US images of 30 patients who have carotid stenosis of 60% or more. The VWV given by our method differed from that given by manual segmentation by 6.7% +/- 5.0%. For the media-adventitia and lumen segmentations, respectively, our method yielded Dice coefficients of 95.2% +/- 1.6%, 94.3% +/- 2.6%, mean absolute distances of 0.3 +/- 0.1 mm, 0.2 +/- 0.1 mm, maximum absolute distances of 0.8 +/- 0.4 mm, 0.6 +/- 0.3 mm, and volume differences of 4.2% +/- 3.1%, 3.4% +/- 2.6%. The realization of a semi-automated segmentation method will accelerate the translation of 3D carotid US to clinical care for the rapid, non-invasive, and economical monitoring of atherosclerotic disease progression and regression during therapy.

  16. Dependence of image quality on image operator and noise for optical diffusion tomography

    NASA Astrophysics Data System (ADS)

    Chang, Jenghwa; Graber, Harry L.; Barbour, Randall L.

    1998-04-01

    By applying linear perturbation theory to the radiation transport equation, the inverse problem of optical diffusion tomography can be reduced to a set of linear equations, W(mu) equals R, where W is the weight function, (mu) are the cross- section perturbations to be imaged, and R is the detector readings perturbations. We have studied the dependence of image quality on added systematic error and/or random noise in W and R. Tomographic data were collected from cylindrical phantoms, with and without added inclusions, using Monte Carlo methods. Image reconstruction was accomplished using a constrained conjugate gradient descent method. Result show that accurate images containing few artifacts are obtained when W is derived from a reference states whose optical thickness matches that of the unknown teste medium. Comparable image quality was also obtained for unmatched W, but the location of the target becomes more inaccurate as the mismatch increases. Results of the noise study show that image quality is much more sensitive to noise in W than in R, and the impact of noise increase with the number of iterations. Images reconstructed after pure noise was substituted for R consistently contain large peaks clustered about the cylinder axis, which was an initially unexpected structure. In other words, random input produces a non- random output. This finding suggests that algorithms sensitive to the evolution of this feature could be developed to suppress noise effects.

  17. Dual-source spiral CT with pitch up to 3.2 and 75 ms temporal resolution: Image reconstruction and assessment of image quality

    SciTech Connect

    Flohr, Thomas G.; Leng Shuai; Yu Lifeng; Allmendinger, Thomas; Bruder, Herbert; Petersilka, Martin; Eusemann, Christian D.; Stierstorfer, Karl; Schmidt, Bernhard; McCollough, Cynthia H.

    2009-12-15

    Purpose: To present the theory for image reconstruction of a high-pitch, high-temporal-resolution spiral scan mode for dual-source CT (DSCT) and evaluate its image quality and dose. Methods: With the use of two x-ray sources and two data acquisition systems, spiral CT exams having a nominal temporal resolution per image of up to one-quarter of the gantry rotation time can be acquired using pitch values up to 3.2. The scan field of view (SFOV) for this mode, however, is limited to the SFOV of the second detector as a maximum, depending on the pitch. Spatial and low contrast resolution, image uniformity and noise, CT number accuracy and linearity, and radiation dose were assessed using the ACR CT accreditation phantom, a 30 cm diameter cylindrical water phantom or a 32 cm diameter cylindrical PMMA CTDI phantom. Slice sensitivity profiles (SSPs) were measured for different nominal slice thicknesses, and an anthropomorphic phantom was used to assess image artifacts. Results were compared between single-source scans at pitch=1.0 and dual-source scans at pitch=3.2. In addition, image quality and temporal resolution of an ECG-triggered version of the DSCT high-pitch spiral scan mode were evaluated with a moving coronary artery phantom, and radiation dose was assessed in comparison with other existing cardiac scan techniques. Results: No significant differences in quantitative measures of image quality were found between single-source scans at pitch=1.0 and dual-source scans at pitch=3.2 for spatial and low contrast resolution, CT number accuracy and linearity, SSPs, image uniformity, and noise. The pitch value (1.6{<=}pitch{<=}3.2) had only a minor impact on radiation dose and image noise when the effective tube current time product (mA s/pitch) was kept constant. However, while not severe, artifacts were found to be more prevalent for the dual-source pitch=3.2 scan mode when structures varied markedly along the z axis, particularly for head scans. Images of the moving coronary artery phantom acquired with the ECG-triggered high-pitch scan mode were visually free from motion artifacts at heart rates of 60 and 70 bpm. However, image quality started to deteriorate for higher heart rates. At equivalent image quality, the ECG-triggered high-pitch scan mode demonstrated lower radiation dose than other cardiac scan techniques on the same DSCT equipment (25% and 60% dose reduction compared to ECG-triggered sequential step-and-shoot and ECG-gated spiral with x-ray pulsing). Conclusions: A high-pitch (up to pitch=3.2), high-temporal-resolution (up to 75 ms) dual-source CT scan mode produced equivalent image quality relative to single-source scans using a more typical pitch value (pitch=1.0). The resultant reduction in the overall acquisition time may offer clinical advantage for cardiovascular, trauma, and pediatric CT applications. In addition, ECG-triggered high-pitch scanning may be useful as an alternative to ECG-triggered sequential scanning for patients with low to moderate heart rates up to 70 bpm, with the potential to scan the heart within one heart beat at reduced radiation dose.

  18. Monitoring of arterial wall remodelling in atherosclerotic rabbits with a magnetic resonance imaging contrast agent binding to matrix metalloproteinases

    PubMed Central

    Hyafil, Fabien; Vucic, Esad; Cornily, Jean-Christophe; Sharma, Rahul; Amirbekian, Vardan; Blackwell, Francis; Lancelot, Eric; Corot, Claire; Fuster, Valentin; Galis, Zorina S.; Feldman, Laurent J.; Fayad, Zahi A.

    2011-01-01

    Aims P947 is a gadolinium-based magnetic resonance imaging (MRI) contrast agent with high affinity for several matrix metalloproteinases (MMPs) involved in arterial wall remodelling. We tested whether the intensity of enhancement detected in vivo in the arterial wall with P947 and MRI correlates with actual tissue MMP-related enzymatic activity measured in a rabbit atherosclerotic model subjected to dietary manipulations. Methods and results Aortas of 15 rabbits in which atherosclerotic lesions were induced by balloon angioplasty and 4 months of hypercholesterolaemic diet were imaged at ‘baseline’ with P947-enhanced MRI. Atherosclerotic rabbits were divided into three groups: five rabbits were sacrificed (‘baseline’ group); five rabbits continued to be fed a lipid-supplemented diet (‘high-fat’ group); and five rabbits were switched from atherogenic to a purified chow diet (‘low-fat’ group). Four months later, a second P947-enhanced MRI was acquired in the 10 remaining rabbits. A significantly lower signal was detected in the aortic wall of rabbits from the ‘low-fat’ group as compared with rabbits from the ‘high-fat’ group (21 ± 6 vs. 46 ± 3%, respectively; P = 0.04). Such differences were not detected with the contrast agent P1135, which lacks the MMP-specific peptide sequence. In addition, the intensity of aortic wall enhancement detected with MRI after injection of P947 strongly correlated with actual MMP-2 gelatinolytic activity measured in corresponding aortic segments using zymography (r = 0.87). Conclusion P947-enhanced MRI can distinguish dietary-induced variations in MMP-related enzymatic activity within plaques in an experimental atherosclerotic model, supporting its utility as a clinical imaging tool for in vivo detection of arterial wall remodelling. PMID:21118852

  19. Image quality vs. sensitivity: fundamental sensor system engineering

    NASA Astrophysics Data System (ADS)

    Schueler, Carl F.

    2008-08-01

    This paper focuses on the fundamental system engineering tradeoff driving almost all remote sensing design efforts, affecting complexity, cost, performance, schedule, and risk: image quality vs. sensitivity. This single trade encompasses every aspect of performance, including radiometric accuracy, dynamic range and precision, as well as spatial, spectral, and temporal coverage and resolution. This single trade also encompasses every aspect of design, including mass, dimensions, power, orbit selection, spacecraft interface, sensor and spacecraft functional trades, pointing or scanning architecture, sensor architecture (e.g., field-of-view, optical form, aperture, f/#, material properties), electronics, mechanical and thermal properties. The relationship between image quality and sensitivity is introduced based on the concepts of modulation transfer function (MTF) and signal-to-noise ratio (SNR) with examples to illustrate the balance to be achieved by the system architect to optimize cost, complexity, performance and risk relative to end-user requirements.

  20. Exploring V1 by modeling the perceptual quality of images.

    PubMed

    Zhang, Fan; Jiang, Wenfei; Autrusseau, Florent; Lin, Weisi

    2014-01-01

    We propose an image quality model based on phase and amplitude differences between a reference and a distorted image. The proposed model is motivated by the fact that polar representations can separate visual information in a more independent and efficient manner than Cartesian representations in the primary visual cortex (V1). We subsequently estimate the model parameters from a large subjective data set using maximum likelihood methods. By comparing the various model hypotheses on the functional form about the phase and amplitude, we find that: (a) discrimination of visual orientation is important for quality assessment and yet a coarse level of such discrimination seems sufficient; and (b) a product-based amplitude-phase combination before pooling is effective, suggesting an interesting viewpoint about the functional structure of the simple cells and complex cells in V1. PMID:24464165

  1. The impact of temporal inaccuracies on 4DCT image quality

    SciTech Connect

    Mutaf, Y. D.; Antolak, J. A.; Brinkmann, D. H.

    2007-05-15

    Accurate delineation of target volumes is one of the critical components contributing to the success of image-guided radiotherapy treatments and several imaging modalities are employed to increase the accuracy in target identification. Four-dimensional (4D) techniques are incorporated into existing radiation imaging techniques like computed tomography (CT) to account for the mobility of the target volumes. However, these methods in some cases introduce further inaccuracies in the target delineation when further quality assurance measures are not implemented. A source of commonly observed inaccuracy is the misidentification of the respiration cycles and resulting respiration phase assignments used in the construction of the 4D patient model. The aim of this work is to emphasize the importance of optimal respiration phase assignment during the 4DCT image acquisition process and to perform a quantitative assessment of the effect of inaccurate phase assignments on the overall image quality. The accuracy of the phase assignment was assessed by comparison with an independent calculation of the respiration phases. Misplaced phase assignments manifest themselves as deformations and artifacts in reconstructed images. These effects are quantified as volumetric discrepancies in the localization of target objects represented by spherical phantoms. Measurements are performed using a fully programmable motion phantom designed and built at Mayo Clinic (Rochester, MN). Implementation of a case based independent check and correction procedure is also demonstrated with emphasis on the use of this procedure in the clinical environment. Review of clinical 4D scans performed in this institution showed discrepancies in the phase assignments in about 40% of the cases when compared to our independent calculations. It is concluded that for improved image reconstruction, an independent check of the sorting procedure should be performed for each clinical 4DCT case.

  2. Image quality of an investigational imaging panel for use with the imaging beam line cone-beam CT.

    PubMed

    Beltran, Chris

    2012-01-01

    The purpose of this study was to measure and compare the contrast-to-noise ratio (CNR) as a function of dose for the cone-beam CT (CBCT) produced by the imaging beam line (IBL) for the standard and an investigational imaging panel. Two Siemens Artiste linear accelerators were modified at our institution such that the MV-CBCT would operate under an investigational IBL. The imaging panel from one of the machines was replaced with an investigational imaging panel. After the modification, a set of CBCT for a large and small phantom consisting of eight tissue-equivalent inserts was acquired for the standard imager and for the investigational imager with and without the standard copper plate. Ten dose settings for each phantom using the IBL in combination with the standard and investigational imaging panel were acquired. The CNR for each tissue-equivalent insert was calculated. Resolution measurements in line pairs per mm (lp/mm) of the CBCT for the various imaging panel setups were made. In addition, CBCT images of two patients that were imaged with each panel configuration were displayed for a group of physicians and therapists who were asked to identify the best and worst CBCT for each patient. This was used as a qualitative judge of practical image quality. The CNR of the muscle insert for the large phantom with 1.5 cGy at isocenter was 1.3 for the standard imager, 1.5 for the investigational imager with the copper plate, and 1.9 without the plate. Under the same conditions, the CNR of the trabecular bone insert was 5.9, 7.3, and 9.7, respectively. For the small phantom with the same dose to isocenter, the CNR for muscle was 1.7, 2.1, and 3.3, respectively. For the trabecular bone, the CNR was 8.1, 9.6, and 12.1 respectively. The resolution for 1 cGy at isocenter was 0.37 lp/mm for the standard imager, 0.32 and 0.33 for the investigational imager with and without the copper plate. The qualitative test ranked the CBCT of the investigational imager without the copper plate to be the best image, and the standard imager to be the worst. The investigational imaging panel improves image quality as compared to the standard imager for IBL CBCTs. A 1 cGy IBL CBCT, no matter which imager is used, is sufficient for bony anatomy localization. The investigational imager without the copper plate was judged clinically to produce the best IBL CBCT. PMID:22231211

  3. Assessment of Wall Shear Stress Changes in Arteries and Veins of Arteriovenous Polytetrafluoroethylene Grafts Using Magnetic Resonance Imaging

    SciTech Connect

    Misra, Sanjay Woodrum, David A.; Homburger, Jay; Elkouri, Stephane; Mandrekar, Jayawant N.; Barocas, Victor; Glockner, James F.; Rajan, Dheeraj K.; Mukhopadhyay, Debabrata

    2006-08-15

    The purpose of the study was to determine simultaneously the temporal changes in luminal vessel area, blood flow, and wall shear stress (WSS) in both the anastomosed artery (AA) and vein (AV) of arteriovenous polytetrafluoroethylene (PTFE) grafts. PTFE grafts were placed from the iliac artery to the ipsilateral iliac vein in 12 castrated juvenile male pigs. Contrast-enhanced magnetic resonance angiograpgy with cine phase-contrast magnetic resonance imaging was performed. Luminal vessel area, blood flow, and WSS in the aorta, AA, AV, and inferior vena cava were determined at 3 days (D3), 7 days (D7), and 14 days (D14) after graft placement. Elastin von Gieson staining of the AV was performed. The average WSS of the AA was highest at D3 and then decreased by D7 and D14. In contrast, the average WSS and intima-to-media ratio of the AV increased from D3 to D7 and peaked by D14. Similarly, the average area of the AA was highest by D7 and began to approximate the control artery by D14. The average area of the AV had decreased to its lowest by D7. High blood flows through the AA causes a decrease in average WSS and increase in the average luminal vessel area, whereas at the AV, the average WSS and intima-to-media ratio both increase while the average luminal vessel area decreases.

  4. Quality Improvement Guidelines for Endovascular Treatment of Iliac Artery Occlusive Disease

    SciTech Connect

    Tsetis, Dimitrios Uberoi, Raman

    2008-03-15

    Endovascular therapy is the treatment of choice for type A and the preferred treatment for type B lesions. In selective patients, this type of treatment can be applied in type C and even type D lesions. Ipsilateral femoral, contralateral femoral, and brachial approach and both the intraluminal and subintimal space can be used for successful recanalization. The application of stents has improved the immediate hemodynamic and probably long-term clinical results of iliac percutaneous transluminal angioplasty. However, the superiority of primary or direct stenting over selective stenting has not been proven yet. The choice of stent type depends on lesion morphology and location but otherwise there is insufficient evidence to support the use of a particular stent design. There is insufficient evidence to justify routine use of covered stents. All patients should receive antiaggregant therapy following endovascular recanalization of iliac arteries. There is no consensus regarding prophylaxis with antibiotics in iliac recanalization procedures.

  5. Image Fusion of Preprocedural CTA with Real-time Fluoroscopy to Guide Proper Hepatic Artery Catheterization During Transarterial Chemoembolization of Hepatocellular Carcinoma: A Feasibility Study

    SciTech Connect

    Bargellini, Irene Turini, Francesca; Bozzi, Elena; Lauretti, Dario; Cicorelli, Antonio; Lunardi, Alessandro; Cioni, Roberto; Bartolozzi, Carlo

    2013-04-15

    To assess feasibility of proper hepatic artery catheterization using a 3D model obtained from preprocedural computed tomographic angiography (CTA), fused with real-time fluoroscopy, during transarterial chemoembolization of hepatocellular carcinoma. Twenty consecutive cirrhotic patients with hepatocellular carcinoma undergoing transarterial chemoembolization were prospectively enrolled onto the study. The early arterial phase axial images of the preprocedural CTA were postprocessed on an independent workstation connected to the angiographic system (Innova 4100; GE Healthcare, Milwaukee, WI), obtaining a 3D volume rendering image (VR) that included abdominal aorta, splanchnic arteries, and first and second lumbar vertebrae. The VR image was manually registered to the real-time X-ray fluoroscopy, with the lumbar spine used as the reference. The VR image was then used as guidance to selectively catheterize the proper hepatic artery. The procedure was considered successful when performed with no need for intraarterial contrast injections or angiographic acquisitions. The procedure was successful in 19 (95 %) of 20 patients. In one patient, celiac trunk angiography was required for the presence of a significant ostial stenosis that was underestimated at computed tomography. Time for image reconstruction and registration was <10 min in all cases. The use of preprocedural CTA model with fluoroscopy enables confident and direct catheterization of the proper hepatic artery with no need for preliminary celiac trunk angiography, thus reducing radiation exposure and contrast media administration.

  6. Beef quality parameters estimation using ultrasound and color images

    PubMed Central

    2015-01-01

    Background Beef quality measurement is a complex task with high economic impact. There is high interest in obtaining an automatic quality parameters estimation in live cattle or post mortem. In this paper we set out to obtain beef quality estimates from the analysis of ultrasound (in vivo) and color images (post mortem), with the measurement of various parameters related to tenderness and amount of meat: rib eye area, percentage of intramuscular fat and backfat thickness or subcutaneous fat. Proposal An algorithm based on curve evolution is implemented to calculate the rib eye area. The backfat thickness is estimated from the profile of distances between two curves that limit the steak and the rib eye, previously detected. A model base in Support Vector Regression (SVR) is trained to estimate the intramuscular fat percentage. A series of features extracted on a region of interest, previously detected in both ultrasound and color images, were proposed. In all cases, a complete evaluation was performed with different databases including: color and ultrasound images acquired by a beef industry expert, intramuscular fat estimation obtained by an expert using a commercial software, and chemical analysis. Conclusions The proposed algorithms show good results to calculate the rib eye area and the backfat thickness measure and profile. They are also promising in predicting the percentage of intramuscular fat. PMID:25734452

  7. Three-dimensional Pseudo-continuous Arterial Spin Label Non-contrast Enhanced Perfusion Imaging of Head and Neck Tumors with High-field MR System.

    PubMed

    Chen, Yu; Duan, Miao; Zhou, Hai-Long; Shi, Kai-Ning; Sun, Zhao-Yong; Bai, Chun-Mei; Jia, Ning; Zhang, Tao; Chen, Xing-Ming; Hu, Ke; Zhang, Zhu-Hua; Jin, Zheng-Yu

    2015-10-31

    Objective To evaluate the feasibility of three-dimensional pseudo-continuous arterial spin label (3D pCASL) non-contrast enhanced perfusion imaging applied to head and neck tumors in high-field MR and detect the effects of different postlabeling delay (PLD) time on image quality and the reliability of repeated measurements of tumor blood flow (BF) in different 3D pCASL groups. Methods In this prospective study,all the 25 patients received neck 3D pCASL non-contrast enhanced perfusion examinations in a 3.0 T MR system by using an 8-channel head and neck joint coil. Conventional T1-weighted(TIWI) and T2-weighted imaging (T2WI) were performed firstly. Finally,three 3D pCASL with different PLD time[ASL1(PLD1=1525 ms),ASL2(PLD2=2025 ms),ASL3(PLD3=2525 ms)]were acquired. Patients' perfusion-weighted images acquired from different 3D pCASL sequences underwent the analysis of signal to noise ratio (SNR) and contrast noise ratio (CNR) for tumors. Two observers performed the qualitative assessments on spiral artifacts and vascular artifacts of perfusion-weighted images from different 3D pCASL sequences. Blood flow (BF) of tumors from different 3D pCASL sequences were measured by the two observers respectively for the first time and by observer 2 for the second time. Results Seventeen enrolled patients (age:50.1±12.7 years,M/F=10:7) with histopathologic Results underwent the evaluation of image quality and measurements of BF values. The SNRs and CNRs of ASL1,ASL2,and ASL3 showed a descending trendency. SNRs (P=0.011)and CNRs(P=0.009) of ASL1 were significant higher than those of ASL3. There was no significant difference of scores of spiral artifacts among the three ASL groups (P=0.932). The scores of vascular artifacts of ASL1,ASL2,and ASL3 showed a descending trendency,also. And scores of ASL1 was significant higher than that of ASL3(P=0.000). The intraclass correlation coefficient (ICC) of intre-and intraobserver were high (ICC>0.9). Although the BF values of ASL1,ASL2,and ASL3 showed an ascending trendency,there was no significant difference among the three groups (P=0.977). Conclusion s The 3D pCASL no-contrast enhanced perfusion MR imaging can be used for head and neck tumor. The image quality of perfusion weighted images and reliability of BF measurements were satisfied. The 3D pCASL series with PLD of 1525 ms and 2025 ms have better image quality than PLD of 2525 ms. And BF values do not show significant statistic difference among the three groups. Therefore,3D pCASL series with PLD of 1525 ms and 2025 ms are more suitable for the perfusion imaging of head and neck tumors.
    . PMID:26564509

  8. Coronary arterial dynamics computation with medical-image-based time-dependent anatomical models and element-based zero-stress state estimates

    NASA Astrophysics Data System (ADS)

    Takizawa, Kenji; Torii, Ryo; Takagi, Hirokazu; Tezduyar, Tayfun E.; Xu, Xiao Y.

    2014-10-01

    We propose a method for coronary arterial dynamics computation with medical-image-based time-dependent anatomical models. The objective is to improve the computational analysis of coronary arteries for better understanding of the links between the atherosclerosis development and mechanical stimuli such as endothelial wall shear stress and structural stress in the arterial wall. The method has two components. The first one is element-based zero-stress (ZS) state estimation, which is an alternative to prestress calculation. The second one is a "mixed ZS state" approach, where the ZS states for different elements in the structural mechanics mesh are estimated with reference configurations based on medical images coming from different instants within the cardiac cycle. We demonstrate the robustness of the method in a patient-specific coronary arterial dynamics computation where the motion of a thin strip along the arterial surface and two cut surfaces at the arterial ends is specified to match the motion extracted from the medical images.

  9. Image Quality Improvement in Adaptive Optics Scanning Laser Ophthalmoscopy Assisted Capillary Visualization Using B-spline-based Elastic Image Registration

    PubMed Central

    Uji, Akihito; Ooto, Sotaro; Hangai, Masanori; Arichika, Shigeta; Yoshimura, Nagahisa

    2013-01-01

    Purpose To investigate the effect of B-spline-based elastic image registration on adaptive optics scanning laser ophthalmoscopy (AO-SLO)-assisted capillary visualization. Methods AO-SLO videos were acquired from parafoveal areas in the eyes of healthy subjects and patients with various diseases. After nonlinear image registration, the image quality of capillary images constructed from AO-SLO videos using motion contrast enhancement was compared before and after B-spline-based elastic (nonlinear) image registration performed using ImageJ. For objective comparison of image quality, contrast-to-noise ratios (CNRS) for vessel images were calculated. For subjective comparison, experienced ophthalmologists ranked images on a 5-point scale. Results All AO-SLO videos were successfully stabilized by elastic image registration. CNR was significantly higher in capillary images stabilized by elastic image registration than in those stabilized without registration. The average ratio of CNR in images with elastic image registration to CNR in images without elastic image registration was 2.10 ± 1.73, with no significant difference in the ratio between patients and healthy subjects. Improvement of image quality was also supported by expert comparison. Conclusions Use of B-spline-based elastic image registration in AO-SLO-assisted capillary visualization was effective for enhancing image quality both objectively and subjectively. PMID:24265796

  10. Image gathering and digital restoration for fidelity and visual quality

    NASA Technical Reports Server (NTRS)

    Huck, Friedrich O.; Alter-Gartenberg, Rachel; Rahman, Zia-Ur

    1991-01-01

    The fidelity and resolution of the traditional Wiener restorations given in the prevalent digital processing literature can be significantly improved when the transformations between the continuous and discrete representations in image gathering and display are accounted for. However, the visual quality of these improved restorations also is more sensitive to the defects caused by aliasing artifacts, colored noise, and ringing near sharp edges. In this paper, these visual defects are characterized, and methods for suppressing them are presented. It is demonstrated how the visual quality of fidelity-maximized images can be improved when (1) the image-gathering system is specifically designed to enhance the performance of the image-restoration algorithm, and (2) the Wiener filter is combined with interactive Gaussian smoothing, synthetic high edge enhancement, and nonlinear tone-scale transformation. The nonlinear transformation is used primarily to enhance the spatial details that are often obscurred when the normally wide dynamic range of natural radiance fields is compressed into the relatively narrow dynamic range of film and other displays.

  11. Positron emission tomography/magnetic resonance hybrid scanner imaging of cerebral blood flow using (15)O-water positron emission tomography and arterial spin labeling magnetic resonance imaging in newborn piglets.

    PubMed

    Andersen, Julie B; Henning, William S; Lindberg, Ulrich; Ladefoged, Claes N; Højgaard, Liselotte; Greisen, Gorm; Law, Ian

    2015-11-01

    Abnormality in cerebral blood flow (CBF) distribution can lead to hypoxic-ischemic cerebral damage in newborn infants. The aim of the study was to investigate minimally invasive approaches to measure CBF by comparing simultaneous (15)O-water positron emission tomography (PET) and single TI pulsed arterial spin labeling (ASL) magnetic resonance imaging (MR) on a hybrid PET/MR in seven newborn piglets. Positron emission tomography was performed with IV injections of 20?MBq and 100?MBq (15)O-water to confirm CBF reliability at low activity. Cerebral blood flow was quantified using a one-tissue-compartment-model using two input functions: an arterial input function (AIF) or an image-derived input function (IDIF). The mean global CBF (95% CI) PET-AIF, PET-IDIF, and ASL at baseline were 27 (23; 32), 34 (31; 37), and 27 (22; 32) mL/100?g per minute, respectively. At acetazolamide stimulus, PET-AIF, PET-IDIF, and ASL were 64 (55; 74), 76 (70; 83) and 79 (67; 92) mL/100?g per minute, respectively. At baseline, differences between PET-AIF, PET-IDIF, and ASL were 22% (P<0.0001) and -0.7% (P=0.9). At acetazolamide, differences between PET-AIF, PET-IDIF, and ASL were 19% (P=0.001) and 24% (P=0.0003). In conclusion, PET-IDIF overestimated CBF. Injected activity of 20?MBq (15)O-water had acceptable concordance with 100?MBq, without compromising image quality. Single TI ASL was questionable for regional CBF measurements. Global ASL CBF and PET CBF were congruent during baseline but not during hyperperfusion. PMID:26058699

  12. Objective assessment of image quality. IV. Application to adaptive optics.

    PubMed

    Barrett, Harrison H; Myers, Kyle J; Devaney, Nicholas; Dainty, Christopher

    2006-12-01

    The methodology of objective assessment, which defines image quality in terms of the performance of specific observers on specific tasks of interest, is extended to temporal sequences of images with random point spread functions and applied to adaptive imaging in astronomy. The tasks considered include both detection and estimation, and the observers are the optimal linear discriminant (Hotelling observer) and the optimal linear estimator (Wiener). A general theory of first- and second-order spatiotemporal statistics in adaptive optics is developed. It is shown that the covariance matrix can be rigorously decomposed into three terms representing the effect of measurement noise, random point spread function, and random nature of the astronomical scene. Figures of merit are developed, and computational methods are discussed. PMID:17106464

  13. Objective assessment of image quality. IV. Application to adaptive optics

    PubMed Central

    Barrett, Harrison H.; Myers, Kyle J.; Devaney, Nicholas; Dainty, Christopher

    2008-01-01

    The methodology of objective assessment, which defines image quality in terms of the performance of specific observers on specific tasks of interest, is extended to temporal sequences of images with random point spread functions and applied to adaptive imaging in astronomy. The tasks considered include both detection and estimation, and the observers are the optimal linear discriminant (Hotelling observer) and the optimal linear estimator (Wiener). A general theory of first- and second-order spatiotemporal statistics in adaptive optics is developed. It is shown that the covariance matrix can be rigorously decomposed into three terms representing the effect of measurement noise, random point spread function, and random nature of the astronomical scene. Figures of merit are developed, and computational methods are discussed. PMID:17106464

  14. Cross-layer Energy Optimization Under Image Quality Constraints for Wireless Image Transmissions.

    PubMed

    Yang, Na; Demirkol, Ilker; Heinzelman, Wendi

    2012-01-01

    Wireless image transmission is critical in many applications, such as surveillance and environment monitoring. In order to make the best use of the limited energy of the battery-operated cameras, while satisfying the application-level image quality constraints, cross-layer design is critical. In this paper, we develop an image transmission model that allows the application layer (e.g., the user) to specify an image quality constraint, and optimizes the lower layer parameters of transmit power and packet length, to minimize the energy dissipation in image transmission over a given distance. The effectiveness of this approach is evaluated by applying the proposed energy optimization to a reference ZigBee system and a WiFi system, and also by comparing to an energy optimization study that does not consider any image quality constraint. Evaluations show that our scheme outperforms the default settings of the investigated commercial devices and saves a significant amount of energy at middle-to-large transmission distances. PMID:23508852

  15. The Effect of Opponent Noise on Image Quality Garrett M. Johnson*

    E-print Network

    Johnson, Garrett M.

    The Effect of Opponent Noise on Image Quality Garrett M. Johnson* and Mark D. Fairchild Munsell A psychophysical experiment was performed examining the effect of luminance and chromatic noise on perceived image on perceived image quality. Averaged across the scenes, the original noise-free image was determined

  16. A hyperspectral imaging prototype for online quality evaluation of pickling cucumbers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A hyperspectral imaging prototype was developed for online evaluation of external and internal quality of pickling cucumbers. The prototype had several new, unique features including simultaneous reflectance and transmittance imaging and inline, real time calibration of hyperspectral images of each ...

  17. Uniform framework for the objective assessment and optimisation of radiotherapy image quality 

    E-print Network

    Reilly, Andrew James

    2011-07-05

    Image guidance has rapidly become central to current radiotherapy practice. A uniform framework is developed for evaluating image quality across all imaging modalities by modelling the ‘universal phantom’: breaking any ...

  18. TU-B-19A-01: Image Registration II: TG132-Quality Assurance for Image Registration

    SciTech Connect

    Brock, K; Mutic, S

    2014-06-15

    AAPM Task Group 132 was charged with a review of the current approaches and solutions for image registration in radiotherapy and to provide recommendations for quality assurance and quality control of these clinical processes. As the results of image registration are always used as the input of another process for planning or delivery, it is important for the user to understand and document the uncertainty associate with the algorithm in general and the Result of a specific registration. The recommendations of this task group, which at the time of abstract submission are currently being reviewed by the AAPM, include the following components. The user should understand the basic image registration techniques and methods of visualizing image fusion. The disclosure of basic components of the image registration by commercial vendors is critical in this respect. The physicists should perform end-to-end tests of imaging, registration, and planning/treatment systems if image registration is performed on a stand-alone system. A comprehensive commissioning process should be performed and documented by the physicist prior to clinical use of the system. As documentation is important to the safe implementation of this process, a request and report system should be integrated into the clinical workflow. Finally, a patient specific QA practice should be established for efficient evaluation of image registration results. The implementation of these recommendations will be described and illustrated during this educational session. Learning Objectives: Highlight the importance of understanding the image registration techniques used in their clinic. Describe the end-to-end tests needed for stand-alone registration systems. Illustrate a comprehensive commissioning program using both phantom data and clinical images. Describe a request and report system to ensure communication and documentation. Demonstrate an clinically-efficient patient QA practice for efficient evaluation of image registration.

  19. Image Quality of the Helioseismic and Magnetic Imager (HMI) Onboard the Solar Dynamics Observatory (SDO)

    NASA Technical Reports Server (NTRS)

    Wachter, R.; Schou, Jesper; Rabello-Soares, M. C.; Miles, J. W.; Duvall, T. L., Jr.; Bush, R. I.

    2011-01-01

    We describe the imaging quality of the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) as measured during the ground calibration of the instrument. We describe the calibration techniques and report our results for the final configuration of HMI. We present the distortion, modulation transfer function, stray light,image shifts introduced by moving parts of the instrument, best focus, field curvature, and the relative alignment of the two cameras. We investigate the gain and linearity of the cameras, and present the measured flat field.

  20. Microscope-based near-infrared stereo-imaging system for quantifying the motion of the murine epicardial coronary arteries in vivo.

    PubMed

    Long, David S; Zhu, Hui; Friedman, Morton H

    2013-09-01

    Atherosclerosis is a leading cause of mortality in industrialized countries. In addition to "traditional" systemic risk factors for atherosclerosis, the geometry and motion of coronary arteries may contribute to individual susceptibility to the development and progression of disease in these vessels. To be able to test this, we have developed a high-speed (?40 frames per second) microscope-based stereo-imaging system to quantify the motion of epicardial coronary arteries of mice. Using near-infrared nontargeted quantum dots as an imaging contrast agent, we synchronously acquired paired images of a surgically exposed murine heart, from which the three-dimensional geometry of the coronary arteries was reconstructed. The reconstructed geometry was tracked frame by frame through the cardiac cycle to quantify the in vivo motion of the vessel, from which displacements, curvature, and torsion parameters were derived. Illustrative results for a C57BL/6J mouse are presented. PMID:24057233

  1. Sleep Quality and Emotional Correlates in Taiwanese Coronary Artery Bypass Graft Patients 1 Week and 1 Month after Hospital Discharge: A Repeated Descriptive Correlational Study

    PubMed Central

    Yang, Pei-Lin; Huang, Guey-Shiun; Tsai, Chien-Sung; Lou, Meei-Fang

    2015-01-01

    Background Poor sleep quality is a common health problem for coronary artery bypass graft patients, however few studies have evaluated sleep quality during the period immediately following hospital discharge. Purpose The aim of this study was to investigate changes in sleep quality and emotional correlates in coronary artery bypass graft patients in Taiwan at 1 week and 1 month after hospital discharge. Methods We used a descriptive correlational design for this study. One week after discharge, 87 patients who had undergone coronary artery bypass surgery completed two structured questionnaires: the Pittsburgh Sleep Quality Index and the Hospital Anxiety and Depression Scale. Three weeks later (1 month after discharge) the patients completed the surveys again. Pearson correlations, t-tests, ANOVA and linear multiple regression analysis were used to analyze the data. Results A majority of the participants had poor sleep quality at 1 week (82.8%) and 1 month (66.7%) post-hospitalization, based on the global score of the Pittsburgh Sleep Quality Index. Despite poor sleep quality at both time-points the sleep quality at 1 month was significantly better than at 1-week post hospitalization. Poorer sleep quality correlated with older age, poorer heart function, anxiety and depression. The majority of participants had normal levels of anxiety at 1 week (69.0%) and 1 month (88.5%) as measured by the Hospital Anxiety and Depression Scale. However, some level of depression was seen at 1 week (78.1%) and 1 month (59.7%). Depression was a significant predictor of sleep quality at 1 week; at 1 month after hospital discharge both anxiety and depression were significant predictors of sleep quality. Conclusion Sleep quality, anxiety and depression all significantly improved 1 month after hospital discharge. However, more than half of the participants continued to have poor sleep quality and some level of depression. Health care personnel should be encouraged to assess sleep and emotional status in patients after coronary artery bypass surgery and offer them appropriate management strategies to improve sleep and reduce anxiety and depression. PMID:26291524

  2. Uterine Artery Embolization to Treat Uterine Adenomyosis with or without Uterine Leiomyomata: Results of Symptom Control and Health-Related Quality of Life 40 Months after Treatment

    SciTech Connect

    Froeling, V. Scheurig-Muenkler, C. Hamm, B. Kroencke, T. J.

    2012-06-15

    Purpose: To evaluate the clinical outcome for uterine adenomyosis with or without uterine leiomyomata 40 months after uterine artery embolization (UAE). Methods: Forty women aged 39-56 years (median 46 years) with symptomatic uterine adenomyosis and magnetic resonance imaging findings of uterine adenomyosis with or without combined uterine leiomyomata underwent UAE. Self-perceived changes in clinical symptoms were assessed, and residual symptom severity and health-related quality of life (HRQOL) after UAE were evaluated. Clinical failure was defined as no symptomatic improvement or second invasive therapy after UAE. Results were stratified by the extent of uterine adenomyosis at baseline magnetic resonance imaging. Results: Patients were followed for a median of 40 months (range 5-102 months). UAE led to symptomatic control after UAE in 29 (72.5%) of 40 patients while 11 women underwent hysterectomy (n = 10) or dilatation and curettage (n = 1) for therapy failure. No significant difference between women with pure uterine adenoymosis and women with uterine adenomyosis combined with uterine leiomyomata was observed. Best results were shown for UAE in uterine adenomyosis with uterine leiomyomata predominance as opposed to predominant uterine adenomyosis with minor fibroid disease (clinical failure 0% vs. 31.5%, P = 0.058). Throughout the study group, HRQOL score values increased and symptom severity scores decreased after UAE. Least improvement was noted for women with pure adenomyosis. Conclusions: UAE is clinically effective in the long term in most women with uterine adenomyosis. Symptomatic control and HRQOL were highest in patients with combined disease of uterine adenomyosis but leiomyomata predominance.

  3. Restoration of images degraded by underwater turbulence using structure tensor oriented image quality (STOIQ) metric.

    PubMed

    Kanaev, A V; Hou, W; Restaino, S R; Matt, S; G?adysz, S

    2015-06-29

    Recent advances in image processing for atmospheric propagation have provided a foundation for tackling the similar but perhaps more complex problem of underwater imaging, which is impaired by scattering and optical turbulence. As a result of these impairments underwater imagery suffers from excessive noise, blur, and distortion. Underwater turbulence impact on light propagation becomes critical at longer distances as well as near thermocline and mixing layers. In this work, we demonstrate a method for restoration of underwater images that are severely degraded by underwater turbulence. The key element of the approach is derivation of a structure tensor oriented image quality metric, which is subsequently incorporated into a lucky patch image processing framework. The utility of the proposed image quality measure guided by local edge strength and orientation is emphasized by comparing the restoration results to an unsuccessful restoration obtained with equivalent processing utilizing a standard isotropic metric. Advantages of the proposed approach versus three other state-of-the-art image restoration techniques are demonstrated using the data obtained in the laboratory water tank and in a natural environment underwater experiment. Quantitative comparison of the restoration results is performed via structural similarity index measure and normalized mutual information metric. PMID:26191716

  4. An improved approach for accurate and efficient measurement of common carotid artery intima-media thickness in ultrasound images.

    PubMed

    Li, Qiang; Zhang, Wei; Guan, Xin; Bai, Yu; Jia, Jing

    2014-01-01

    The intima-media thickness (IMT) of common carotid artery (CCA) can serve as an important indicator for the assessment of cardiovascular diseases (CVDs). In this paper an improved approach for automatic IMT measurement with low complexity and high accuracy is presented. 100 ultrasound images from 100 patients were tested with the proposed approach. The ground truth (GT) of the IMT was manually measured for six times and averaged, while the automatic segmented (AS) IMT was computed by the algorithm proposed in this paper. The mean difference±standard deviation between AS and GT IMT is 0.0231±0.0348?mm, and the correlation coefficient between them is 0.9629. The computational time is 0.3223?s per image with MATLAB under Windows XP on an Intel Core 2 Duo CPU E7500 @2.93?GHz. The proposed algorithm has the potential to achieve real-time measurement under Visual Studio. PMID:25215292

  5. Advances in the development of an imaging device for plaque measurement in the area of the carotid artery

    PubMed Central

    Li?ev, La?ezar; Krumnikl, Michal; Škuta, Jaromír; Babiuch, Marek; Farana, Radim

    2014-01-01

    This paper describes the advances in the development and subsequent testing of an imaging device for three-dimensional ultrasound measurement of atherosclerotic plaque in the carotid artery. The embolization from the atherosclerotic carotid plaque is one of the most common causes of ischemic stroke and, therefore, we consider the measurement of the plaque as extremely important. The paper describes the proposed hardware for enhancing the standard ultrasonic probe to provide a possibility of accurate probe positioning and synchronization with the cardiac activity, allowing the precise plaque measurements that were impossible with the standard equipment. The synchronization signal is derived from the output signal of the patient monitor (electrocardiogram (ECG)), processed by a microcontroller-based system, generating the control commands for the linear motion moving the probe. The controlling algorithm synchronizes the movement with the ECG waveform to obtain clear images not disturbed by the heart activity.

  6. Noninvasive Cardiac Imaging in Patients with Known and Suspected Coronary Artery Disease: What is in it for the Interventional Cardiologist?

    PubMed

    Rodriguez-Granillo, Gaston A; Campisi, Roxana; Carrascosa, Patricia

    2016-01-01

    The long-standing coronary artery disease (CAD) paradigm simplified by the discrimination between patients with or without CAD warrants to be revisited by the insightful information provided by noninvasive cardiac imaging, leading to a comprehensive physiopathological assessment rather than a mainly anatomical approach. This review will address (1) the role of non-invasive cardiac imaging for the appropriate selection of stable patients referred to invasive coronary angiography (ICA), and the evolving concept and prognostic implications of myocardial ischemia; (2) the usefulness of computed tomography coronary angiography for the guidance of percutaneous coronary interventions; and (3) the role and potential clinical impact of novel anatomical and functional non-invasive prognostic markers. PMID:26694725

  7. Computerized method for evaluating diagnostic image quality of calcified plaque images in cardiac CT: Validation on a physical dynamic cardiac phantom

    SciTech Connect

    King, Martin; Rodgers, Zachary; Giger, Maryellen L.; Bardo, Dianna M. E.; Patel, Amit R.

    2010-11-15

    Purpose: In cardiac computed tomography (CT), important clinical indices, such as the coronary calcium score and the percentage of coronary artery stenosis, are often adversely affected by motion artifacts. As a result, the expert observer must decide whether or not to use these indices during image interpretation. Computerized methods potentially can be used to assist in these decisions. In a previous study, an artificial neural network (ANN) regression model provided assessability (image quality) indices of calcified plaque images from the software NCAT phantom that were highly agreeable with those provided by expert observers. The method predicted assessability indices based on computer-extracted features of the plaque. In the current study, the ANN-predicted assessability indices were used to identify calcified plaque images with diagnostic calcium scores (based on mass) from a physical dynamic cardiac phantom. The basic assumption was that better quality images were associated with more accurate calcium scores. Methods: A 64-channel CT scanner was used to obtain 500 calcified plaque images from a physical dynamic cardiac phantom at different heart rates, cardiac phases, and plaque locations. Two expert observers independently provided separate sets of assessability indices for each of these images. Separate sets of ANN-predicted assessability indices tailored to each observer were then generated within the framework of a bootstrap resampling scheme. For each resampling iteration, the absolute calcium score error between the calcium scores of the motion-contaminated plaque image and its corresponding stationary image served as the ground truth in terms of indicating images with diagnostic calcium scores. The performances of the ANN-predicted and observer-assigned indices in identifying images with diagnostic calcium scores were then evaluated using ROC analysis. Results: Assessability indices provided by the first observer and the corresponding ANN performed similarly (AUC{sub OBS1}=0.80 [0.73,0.86] vs AUC{sub ANN1}=0.88 [0.82,0.92]) as that of the second observer and the corresponding ANN (AUC{sub OBS2}=0.87 [0.83,0.91] vs AUC{sub ANN2}=0.90 [0.85,0.94]). Moreover, the ANN-predicted indices were generated in a fraction of the time required to obtain the observer-assigned indices. Conclusions: ANN-predicted assessability indices performed similar to observer-assigned assessability indices in identifying images with diagnostic calcium scores from the physical dynamic cardiac phantom. The results of this study demonstrate the potential of using computerized methods for identifying images with diagnostic clinical indices in cardiac CT images.

  8. Patient dose and image quality from mega-voltage cone beam computed tomography imaging

    SciTech Connect

    Gayou, Olivier; Parda, David S.; Johnson, Mark; Miften, Moyed

    2007-02-15

    The evolution of ever more conformal radiation delivery techniques makes the subject of accurate localization of increasing importance in radiotherapy. Several systems can be utilized including kilo-voltage and mega-voltage cone-beam computed tomography (MV-CBCT), CT on rail or helical tomography. One of the attractive aspects of mega-voltage cone-beam CT is that it uses the therapy beam along with an electronic portal imaging device to image the patient prior to the delivery of treatment. However, the use of a photon beam energy in the mega-voltage range for volumetric imaging degrades the image quality and increases the patient radiation dose. To optimize image quality and patient dose in MV-CBCT imaging procedures, a series of dose measurements in cylindrical and anthropomorphic phantoms using an ionization chamber, radiographic films, and thermoluminescent dosimeters was performed. Furthermore, the dependence of the contrast to noise ratio and spatial resolution of the image upon the dose delivered for a 20-cm-diam cylindrical phantom was evaluated. Depending on the anatomical site and patient thickness, we found that the minimum dose deposited in the irradiated volume was 5-9 cGy and the maximum dose was between 9 and 17 cGy for our clinical MV-CBCT imaging protocols. Results also demonstrated that for high contrast areas such as bony anatomy, low doses are sufficient for image registration and visualization of the three-dimensional boundaries between soft tissue and bony structures. However, as the difference in tissue density decreased, the dose required to identify soft tissue boundaries increased. Finally, the dose delivered by MV-CBCT was simulated using a treatment planning system (TPS), thereby allowing the incorporation of MV-CBCT dose in the treatment planning process. The TPS-calculated doses agreed well with measurements for a wide range of imaging protocols.

  9. How does image noise affect actual and predicted human gaze allocation in assessing image quality?

    PubMed

    Röhrbein, Florian; Goddard, Peter; Schneider, Michael; James, Georgina; Guo, Kun

    2015-07-01

    A central research question in natural vision is how to allocate fixation to extract informative cues for scene perception. With high quality images, psychological and computational studies have made significant progress to understand and predict human gaze allocation in scene exploration. However, it is unclear whether these findings can be generalised to degraded naturalistic visual inputs. In this eye-tracking and computational study, we methodically distorted both man-made and natural scenes with Gaussian low-pass filter, circular averaging filter and Additive Gaussian white noise, and monitored participants' gaze behaviour in assessing perceived image qualities. Compared with original high quality images, distorted images attracted fewer numbers of fixations but longer fixation durations, shorter saccade distance and stronger central fixation bias. This impact of image noise manipulation on gaze distribution was mainly determined by noise intensity rather than noise type, and was more pronounced for natural scenes than for man-made scenes. We furthered compared four high performing visual attention models in predicting human gaze allocation in degraded scenes, and found that model performance lacked human-like sensitivity to noise type and intensity, and was considerably worse than human performance measured as inter-observer variance. Furthermore, the central fixation bias is a major predictor for human gaze allocation, which becomes more prominent with increased noise intensity. Our results indicate a crucial role of external noise intensity in determining scene-viewing gaze behaviour, which should be considered in the development of realistic human-vision-inspired attention models. PMID:25982711

  10. Using full-reference image quality metrics for automatic image sharpening

    NASA Astrophysics Data System (ADS)

    Krasula, Lukas; Fliegel, Karel; Le Callet, Patrick; Klíma, Miloš

    2014-05-01

    Image sharpening is a post-processing technique employed for the artificial enhancement of the perceived sharpness by shortening the transitions between luminance levels or increasing the contrast on the edges. The greatest challenge in this area is to determine the level of perceived sharpness which is optimal for human observers. This task is complex because the enhancement is gained only until the certain threshold. After reaching it, the quality of the resulting image drops due to the presence of annoying artifacts. Despite the effort dedicated to the automatic sharpness estimation, none of the existing metrics is designed for localization of this threshold. Nevertheless, it is a very important step towards the automatic image sharpening. In this work, possible usage of full-reference image quality metrics for finding the optimal amount of sharpening is proposed and investigated. The intentionally over-sharpened "anchor image" was included to the calculation as the "anti-reference" and the final metric score was computed from the differences between reference, processed, and anchor versions of the scene. Quality scores obtained from the subjective experiment were used to determine the optimal combination of partial metric values. Five popular fidelity metrics - SSIM, MS-SSIM, IW-SSIM, VIF, and FSIM - were tested. The performance of the proposed approach was then verified in the subjective experiment.

  11. Analysis of filtering techniques and image quality in pixel duplicated images

    NASA Astrophysics Data System (ADS)

    Mehrubeoglu, Mehrube; McLauchlan, Lifford

    2009-08-01

    When images undergo filtering operations, valuable information can be lost besides the intended noise or frequencies due to averaging of neighboring pixels. When the image is enlarged by duplicating pixels, such filtering effects can be reduced and more information retained, which could be critical when analyzing image content automatically. Analysis of retinal images could reveal many diseases at early stage as long as minor changes that depart from a normal retinal scan can be identified and enhanced. In this paper, typical filtering techniques are applied to an early stage diabetic retinopathy image which has undergone digital pixel duplication. The same techniques are applied to the original images for comparison. The effects of filtering are then demonstrated for both pixel duplicated and original images to show the information retention capability of pixel duplication. Image quality is computed based on published metrics. Our analysis shows that pixel duplication is effective in retaining information on smoothing operations such as mean filtering in the spatial domain, as well as lowpass and highpass filtering in the frequency domain, based on the filter window size. Blocking effects due to image compression and pixel duplication become apparent in frequency analysis.

  12. Relations between local and global perceptual image quality and visual masking

    NASA Astrophysics Data System (ADS)

    Alam, Md Mushfiqul; Patil, Pranita; Hagan, Martin T.; Chandler, Damon M.

    2015-03-01

    Perceptual quality assessment of digital images and videos are important for various image-processing applications. For assessing the image quality, researchers have often used the idea of visual masking (or distortion visibility) to design image-quality predictors specifically for the near-threshold distortions. However, it is still unknown that while assessing the quality of natural images, how the local distortion visibilities relate with the local quality scores. Furthermore, the summing mechanism of the local quality scores to predict the global quality scores is also crucial for better prediction of the perceptual image quality. In this paper, the local and global qualities of six images and six distortion levels were measured using subjective experiments. Gabor-noise target was used as distortion in the quality-assessment experiments to be consistent with our previous study [Alam, Vilankar, Field, and Chandler, Journal of Vision, 2014], in which the local root-mean-square contrast detection thresholds of detecting the Gabor-noise target were measured at each spatial location of the undistorted images. Comparison of the results of this quality-assessment experiment and the previous detection experiment shows that masking predicted the local quality scores more than 95% correctly above 15 dB threshold within 5% subject scores. Furthermore, it was found that an approximate squared summation of local-quality scores predicted the global quality scores suitably (Spearman rank-order correlation 0:97).

  13. Coronary Arteries

    MedlinePLUS

    ... and animations for grades K-6. The Coronary Arteries | Share Coronary Circulation The heart muscle, like every ... into two main coronary blood vessels (also called arteries). These coronary arteries branch off into smaller arteries, ...

  14. Image quality in CT: From physical measurements to model observers.

    PubMed

    Verdun, F R; Racine, D; Ott, J G; Tapiovaara, M J; Toroi, P; Bochud, F O; Veldkamp, W J H; Schegerer, A; Bouwman, R W; Giron, I Hernandez; Marshall, N W; Edyvean, S

    2015-12-01

    Evaluation of image quality (IQ) in Computed Tomography (CT) is important to ensure that diagnostic questions are correctly answered, whilst keeping radiation dose to the patient as low as is reasonably possible. The assessment of individual aspects of IQ is already a key component of routine quality control of medical x-ray devices. These values together with standard dose indicators can be used to give rise to 'figures of merit' (FOM) to characterise the dose efficiency of the CT scanners operating in certain modes. The demand for clinically relevant IQ characterisation has naturally increased with the development of CT technology (detectors efficiency, image reconstruction and processing), resulting in the adaptation and evolution of assessment methods. The purpose of this review is to present the spectrum of various methods that have been used to characterise image quality in CT: from objective measurements of physical parameters to clinically task-based approaches (i.e. model observer (MO) approach) including pure human observer approach. When combined together with a dose indicator, a generalised dose efficiency index can be explored in a framework of system and patient dose optimisation. We will focus on the IQ methodologies that are required for dealing with standard reconstruction, but also for iterative reconstruction algorithms. With this concept the previously used FOM will be presented with a proposal to update them in order to make them relevant and up to date with technological progress. The MO that objectively assesses IQ for clinically relevant tasks represents the most promising method in terms of radiologist sensitivity performance and therefore of most relevance in the clinical environment. PMID:26459319

  15. Perceptual image quality assessment: recent progress and trends

    NASA Astrophysics Data System (ADS)

    Lin, Weisi; Narwaria, Manish

    2010-07-01

    Image quality assessment (IQA) is useful in many visual processing systems but challenging to perform in line with the human perception. A great deal of recent research effort has been directed towards IQA. In order to overcome the difficulty and infeasibility of subjective tests in many situations, the aim of such effort is to assess visual quality objectively towards better alignment with the perception of the Human Visual system (HVS). In this work, we review and analyze the recent progress in the areas related to IQA, as well as giving our views whenever possible. Following the recent trends, we discuss the engineering approach in more details, explore the related aspects for feature pooling, and present a case study with machine learning.

  16. Crowdsourcing quality control for Dark Energy Survey images

    E-print Network

    Melchior, P; Drlica-Wagner, A; Rykoff, E S; Abbott, T M C; Abdalla, F B; Allam, S; Benoit-Levy, A; Brooks, D; Buckley-Geer, E; Rosell, A Carnero; Kind, M Carrasco; Carretero, J; Crocce, M; D'Andrea, C B; da Costa, L N; Desai, S; Doel, P; Evrard, A E; Finley, D A; Flaugher, B; Frieman, J; Gaztanaga, E; Gerdes, D W; Gruen, D; Gruendl, R A; Honscheid, K; James, D J; Jarvis, M; Kuehn, K; Li, T S; Maia, M A G; March, M; Marshall, J L; Nord, B; Ogando, R; Plazas, A A; Romer, A K; Sanchez, E; Scarpine, V; Sevilla-Noarbe, I; Smith, R C; Soares-Santos, M; Suchyta, E; Swanson, M E C; Tarle, G; Vikram, V; Walker, A R; Wester, W; Zhang, Y

    2015-01-01

    We have developed a crowdsourcing web application for image quality control employed by the Dark Energy Survey. Dubbed the "DES exposure checker", it renders science-grade images directly to a web browser and allows users to mark problematic features from a set of predefined classes. Users can also generate custom labels and thus help identify previously unknown problem classes. User reports are fed back to hardware and software experts to help mitigate and eliminate recognized issues. We report on the implementation of the application and our experience with its over 100 users, the majority of which are professional or prospective astronomers but not data management experts. We discuss aspects of user training and engagement, and demonstrate how problem reports have been pivotal to rapidly correct artifacts which would likely have been too subtle or infrequent to be recognized otherwise. We conclude with a number of important lessons learned, suggest possible improvements, and recommend this collective explo...

  17. Impact of chopping on image quality in the SIRTF telescope

    NASA Technical Reports Server (NTRS)

    Bottema, M.

    1985-01-01

    The initial Phase-A concept for the Space Infrared Telescope Facility (SIRTF), which was established in 1981, is concerned with a cryogenically cooled, 85 cm diameter, f/24 Ritchey-Chretien telescope, followed by a Multiple Instrument Chamber (MIC), containing six scientific instruments. In 1982, the Phase-A concept was reviewed with the aim to assess the technical readiness for the next phase of development. Various areas of concern were subsequently investigated in three parallel studies by industry. Two of the arising questions are considered in the present paper, taking into account the system and technology implications of achieving diffraction-limited resolution at 2 microns, and the limitations on the size of the imaging field under this condition. The conducted study takes into account an evaluation of the different methods of chopping. Attention is given to the telescope parameters, symmetric chopping, asymmetrical chopping, focus and alignment errors, the wavefront-error budget, and image quality.

  18. An automated system for numerically rating document image quality

    SciTech Connect

    Cannon, M.; Kelly, P.; Iyengar, S.S.; Brener, N.

    1997-04-01

    As part of the Department of Energy document declassification program, the authors have developed a numerical rating system to predict the OCR error rate that they expect to encounter when processing a particular document. The rating algorithm produces a vector containing scores for different document image attributes such as speckle and touching characters. The OCR error rate for a document is computed from a weighted sum of the elements of the corresponding quality vector. The predicted OCR error rate will be used to screen documents that would not be handled properly with existing document processing products.

  19. Evaluation of arterial blood flow heterogeneity via an image-based computational model

    NASA Astrophysics Data System (ADS)

    Burrowes, Kelly S.; Tawhai, Merryn H.; Hunter, Peter J.

    2005-04-01

    A computational model of blood flow through the human pulmonary arterial tree has been developed to investigate the relative influence of branching structure and gravity on blood flow distribution in the human lung. A geometric model of the largest arterial vessels and definitions of the lobar boundaries were first derived using multi-detector row x-ray computed tomography (MDCT) scans from the Lung Atlas. Further accompanying arterial vessels were generated from the MDCT vessel end points into the lobar volumes using a volume filling branching algorithm. A reduced form of the Navier-Stokes equations were solved within the geometric model to simulate pressure, velocity and vessel radius throughout the network. Blood flow results in the anatomically-based model, with and without gravity, and in a symmetric arterial model were compared in order to investigate their relative contributions to blood flow heterogeneity. Results showed a persistent blood flow gradient and flow heterogeneity in the absence of gravitational forces in the anatomically-based model. Results revealed that the asymmetric branching structure of the model was largely responsible for producing this heterogeneity. Analysis of average results in different slice thicknesses illustrated a clear flow gradient due to gravity in 'lower-resolution" data (thicker slices), but on examination of higher resolution data a trend was less obvious. Results suggest that while gravity does influence flow distribution, the influence of the tree branching structure is also a dominant factor. These results are consistent with high-resolution experimental studies that have demonstrated gravity to be only a minor determinant of blood flow distribution.

  20. Interrupted Aortic Arch Associated with Absence of Left Common Carotid Artery: Imaging with MDCT

    SciTech Connect

    Onbas, Omer Olgun, Hasim; Ceviz, Naci; Ors, Rahmi; Okur, Adnan

    2006-06-15

    Interrupted aortic arch (IAA) is a rare severe congenital heart defect defined as complete luminal and anatomic discontinuity between ascending and descending aorta. Although its association with various congenital heart defects has been reported, absence of left common carotid artery (CCA) in patients with IAA has not been reported previously. We report a case of IAA associated with the absence of left CCA which was clearly shown on multidetector-row spiral CT.

  1. Objective and subjective image quality with prospectively gated versus ECG-controlled tube current modulation using 256-slice computed tomographic angiography

    PubMed Central

    Abazid, Rami; Smettei, Osama; Sayed, Sawsan; Harby, Fahad Al; Habeeb, Abdullah Al; Saqqa, Hanaa Al; Mergania, Salma; Selvanayagam, Joseph B.

    2015-01-01

    Introduction Radiation exposure is one of the major limitations of computed tomographic coronary angiography (CTA). The purpose of this study was to compare the objective and subjective image quality and radiation dose using prospective ECG gating (PGA) versus ECG-controlled tube current modulation (ECTCM) scanning techniques. Methods A prospective, single-center study was performed at Prince Sultan Cardiac Centre, Qassim, Saudi Arabia. A total of 104 patients with low-to- intermediate probability of coronary artery disease (CAD) underwent CTA with either PGA or ECTCM acquisition. PGA was performed during the study period and compared with the last 50 CTAs previously done using ECTCM. A 4-point scale was used to assess the image quality subjectively. Objective image quality was assessed using image signal, noise, and signal-to-noise ratio (SNR). Results Patient‘s Baseline characteristics were not different between the two scanning protocols. The 4-point score of subjective image quality showed no significant differences between the PGA and ECTCM scans (2.9 ± 0.7, 2.96 ± 0.7, respectively; p = 0.87). The objective image quality showed significantly higher noise and lower SNR with PGA compared with ECTCM (31 ± 9, 27 ± 9, respectively; p < 0.001 for noise) and (15 ± 5, 17 ± 7, respectively; p < 0.001 for SNR), with no statistical difference in the image signal (434 ± 123, 425 ± 103 HU, respectively, p = 0.7). Radiation exposure was significantly lower with PGA than with ECTCM. The dose-length product (DLP) for PGA was 334 ± 130 mGy, compared with 822 ± 286 mGy for the ECTCM. This corresponds to a 59% reduction in radiation exposure (p < 0.0001). Conclusions Although prospective ECG-triggered axial scanning increased image noise, it maintained subjective image quality and was associated with a 59% reduction in radiation exposure when compared with ECTCM. PMID:26557743

  2. Quality control of VMAT synchronization using portal imaging.

    PubMed

    Bedford, James L; Chajecka-Szczygielska, Honorata; Thomas, Michael D R

    2015-01-01

    For accurate delivery of volumetric-modulated arc therapy (VMAT), the gantry position should be synchronized with the multileaf collimator (MLC) leaf positions and the dose rate. This study, therefore, aims to implement quality control (QC) of VMAT synchronization, with as few arcs as possible and with minimal data handling time, using portal imaging. A steel bar of diameter 12 mm is accurately positioned in the G-T direction, 80 mm laterally from the isocenter. An arc prescription irradiates the bar with a 16 mm × 220 mm field during a complete 360° arc, so as to cast a shadow of the bar onto the portal imager. This results in a sinusoidal sweep of the field and shadow across the portal imager and back. The method is evaluated by simulating gantry position errors of 1°-9° at one control point, dose errors of 2 monitor units to 20 monitor units (MU) at one control point (0.3%-3% overall), and MLC leaf position errors of 1 mm - 6 mm at one control point. Inhomogeneity metrics are defined to characterize the synchronization of all leaves and of individual leaves with respect to the complete set. Typical behavior is also investigated for three models of accelerator. In the absence of simulated errors, the integrated images show uniformity, and with simulated delivery errors, irregular patterns appear. The inhomogeneity metrics increase by 67% due to a 4° gantry position error, 33% due to an 8 MU (1.25%) dose error, and 70% due to a 2 mm MLC leaf position error. The method is more sensitive to errors at gantry angle 90°/270° than at 0°/180° due to the geometry of the test. This method provides fast and effective VMAT QC suitable for inclusion in a monthly accelerator QC program. The test is able to detect errors in the delivery of individual control points, with the possibility of using movie images to further investigate suspicious image features. PMID:25679179

  3. A color image quality assessment using a reduced-reference image machine learning expert

    NASA Astrophysics Data System (ADS)

    Charrier, Christophe; Lebrun, Gilles; Lezoray, Olivier

    2008-01-01

    A quality metric based on a classification process is introduced. The main idea of the proposed method is to avoid the error pooling step of many factors (in frequential and spatial domain) commonly applied to obtain a final quality score. A classification process based on final quality class with respect to the standard quality scale provided by the UIT. Thus, for each degraded color image, a feature vector is computed including several Human Visual System characteristics, such as, contrast masking effect, color correlation, and so on. Selected features are of two kinds: 1) full-reference features and 2) no-reference characteristics. That way, a machine learning expert, providing a final class number is designed.

  4. Prognostic value of automated SPECT scoring system for coronary artery disease in stress myocardial perfusion and fatty acid metabolism imaging.

    PubMed

    Nakata, Tomoaki; Hashimoto, Akiyoshi; Matsuki, Takayuki; Yoshinaga, Keiichiro; Tsukamoto, Kazumasa; Tamaki, Nagara

    2013-01-01

    Quantitative SPECT analysis contributes to the diagnostic and prognostic assessment of coronary artery disease. A novel automated scoring system (heart score view) can provide identical quantitative information to that determined by expert visual analysis. The aim of the present study is to evaluate the prognostic value of the automated SPECT scoring system when applied to stress thallium and resting beta-methyl-iodophenyl pentadecanoic acid (BMIPP) SPECT images. After a preliminary validation of the automated system by comparison with expert visual analyses, outcome data from 151 consecutive patients with suspected or known coronary artery disease without prior myocardial infarction were analyzed using automated SPECT scores on stress thallium and resting BMIPP images. The software quantified abnormalities as summed stress (SSS), summed rest and summed difference scores for stress thallium and as summed BMIPP scores (SBS). Cardiac events occurred over a period of 48 months in 29 (19.2%) patients with diabetes mellitus, a lower left ventricular ejection fraction (LVEF) and more abnormal scores for thallium and BMIPP. Multivariate predictors of all cardiac events included diabetes mellitus and thallium SSS. The global Chi-square value was significantly increased when SSS was added to the clinical information (diabetes mellitus and LVEF). Negative predictive values of thallium SSS and SBS were almost identical at 84% for all cardiac events and 98% for hard cardiac events. Automatically quantified perfusion and BMIPP scores are related to cardiac events and these values can improve the risk stratification of coronary patients particularly when stress thallium imaging is combined with clinical information. PMID:22782310

  5. Measuring saliency in images: which experimental parameters for the assessment of image quality?

    NASA Astrophysics Data System (ADS)

    Fredembach, Clement; Woolfe, Geoff; Wang, Jue

    2012-01-01

    Predicting which areas of an image are perceptually salient or attended to has become an essential pre-requisite of many computer vision applications. Because observers are notoriously unreliable in remembering where they look a posteriori, and because asking where they look while observing the image necessarily in uences the results, ground truth about saliency and visual attention has to be obtained by gaze tracking methods. From the early work of Buswell and Yarbus to the most recent forays in computer vision there has been, perhaps unfortunately, little agreement on standardisation of eye tracking protocols for measuring visual attention. As the number of parameters involved in experimental methodology can be large, their individual in uence on the nal results is not well understood. Consequently, the performance of saliency algorithms, when assessed by correlation techniques, varies greatly across the literature. In this paper, we concern ourselves with the problem of image quality. Specically: where people look when judging images. We show that in this case, the performance gap between existing saliency prediction algorithms and experimental results is signicantly larger than otherwise reported. To understand this discrepancy, we rst devise an experimental protocol that is adapted to the task of measuring image quality. In a second step, we compare our experimental parameters with the ones of existing methods and show that a lot of the variability can directly be ascribed to these dierences in experimental methodology and choice of variables. In particular, the choice of a task, e.g., judging image quality vs. free viewing, has a great impact on measured saliency maps, suggesting that even for a mildly cognitive task, ground truth obtained by free viewing does not adapt well. Careful analysis of the prior art also reveals that systematic bias can occur depending on instrumental calibration and the choice of test images. We conclude this work by proposing a set of parameters, tasks and images that can be used to compare the various saliency prediction methods in a manner that is meaningful for image quality assessment.

  6. Virtual monochromatic imaging in dual-source dual-energy CT: Radiation dose and image quality

    SciTech Connect

    Yu Lifeng; Christner, Jodie A.; Leng Shuai; Wang Jia; Fletcher, Joel G.; McCollough, Cynthia H.

    2011-12-15

    Purpose: To evaluate the image quality of virtual monochromatic images synthesized from dual-source dual-energy computed tomography (CT) in comparison with conventional polychromatic single-energy CT for the same radiation dose. Methods: In dual-energy CT, besides the material-specific information, one may also synthesize monochromatic images at different energies, which can be used for routine diagnosis similar to conventional polychromatic single-energy images. In this work, the authors assessed whether virtual monochromatic images generated from dual-source CT scanners had an image quality similar to that of polychromatic single-energy images for the same radiation dose. First, the authors provided a theoretical analysis of the optimal monochromatic energy for either the minimum noise level or the highest iodine contrast to noise ratio (CNR) for a given patient size and dose partitioning between the low- and high-energy scans. Second, the authors performed an experimental study on a dual-source CT scanner to evaluate the noise and iodine CNR in monochromatic images. A thoracic phantom with three sizes of attenuating rings was used to represent four adult sizes. For each phantom size, three dose partitionings between the low-energy (80 kV) and the high-energy (140 kV) scans were used in the dual-energy scan. Monochromatic images at eight energies (40 to 110 keV) were generated for each scan. Phantoms were also scanned at each of the four polychromatic single energy (80, 100, 120, and 140 kV) with the same radiation dose. Results: The optimal virtual monochromatic energy depends on several factors: phantom size, partitioning of the radiation dose between low- and high-energy scans, and the image quality metrics to be optimized. With the increase of phantom size, the optimal monochromatic energy increased. With the increased percentage of radiation dose on the low energy scan, the optimal monochromatic energy decreased. When maximizing the iodine CNR in monochromatic images, the optimal energy was lower than that when minimizing noise level. When the total radiation dose was equally distributed between low and high energy in dual-energy scans, for minimum noise, the optimal energies were 68, 71, 74, and 77 keV for small, medium, large, and extra-large (xlarge) phantoms, respectively; for maximum iodine CNR, the optimal energies were 66, 68, 70, 72 keV. With the optimal monochromatic energy, the noise level was similar to and the CNR was better than that in a single-energy scan at 120 kV for the same radiation dose. Compared to an 80 kV scan, however, the iodine CNR in monochromatic images was lower for the small, medium, and large phantoms. Conclusions: In dual-source dual-energy CT, optimal virtual monochromatic energy depends on patient size, dose partitioning, and the image quality metric optimized. With the optimal monochromatic energy, the noise level was similar to and the iodine CNR was better than that in 120 kV images for the same radiation dose. Compared to single-energy 80 kV images, the iodine CNR in virtual monochromatic images was lower for small to large phantom sizes.

  7. A comprehensive study on the relationship between image quality and imaging dose in low-dose cone beam CT

    E-print Network

    Yan, Hao; Jia, Xun; Jiang, Steve B

    2011-01-01

    While compressed sensing (CS) based reconstructions have been developed for low-dose CBCT, a clear understanding on the relationship between the image quality and imaging dose at low dose levels is needed. In this paper, we qualitatively investigate this subject in a comprehensive manner with extensive experimental and simulation studies. The basic idea is to plot image quality and imaging dose together as functions of number of projections and mAs per projection over the whole clinically relevant range. A clear understanding on the tradeoff between image quality and dose can be achieved and optimal low-dose CBCT scan protocols can be developed for various imaging tasks in IGRT. Main findings of this work include: 1) Under the CS framework, image quality has little degradation over a large dose range, and the degradation becomes evident when the dose scan protocols likely fall in the dose range of 40-100 ...

  8. Clinical, Laboratory, and Imaging Characteristics of Transient Ischemic Attack Caused by Large Artery Lesions: A Comparison between Carotid and Intracranial Arteries

    PubMed Central

    Uehara, Toshiyuki; Ohara, Tomoyuki; Toyoda, Kazunori; Nagatsuka, Kazuyuki; Minematsu, Kazuo

    2015-01-01

    Background/Aims The aims of this study were to determine the differences in clinical characteristics and the risk of ischemic stroke between patients with transient ischemic attack (TIA) attributable to extracranial carotid and intracranial artery occlusive lesions. Methods Among 445 patients admitted to our stroke care unit within 48 h of TIA onset between April 2008 and December 2013, 85 patients (63 men, mean age 69.4 years) with large artery occlusive lesions relevant to symptoms were included in this study. The primary endpoints were ischemic stroke at 2 and 90 days after TIA onset. Results Twenty-eight patients had carotid artery occlusive lesions (extracranial group), and 57 patients had intracranial artery occlusive lesions (intracranial group). Patients in the intracranial group were significantly younger, had lower levels of fibrinogen, and were less likely to have occlusion when compared with those in the extracranial group. Eleven patients in the extracranial group and none in the intracranial group underwent revascularization procedures within 90 days of TIA onset. The 2-day risk (14.2 vs. 0%, p = 0.044) and the 90-day risk (17.1 vs. 0%, p = 0.020) of ischemic stroke after TIA onset were significantly higher in the intracranial group than in the extracranial group. Conclusions Among our patients with TIA caused by large artery disease, patients with intracranial artery occlusive lesions were more frequent and were at higher risk of early ischemic stroke than those with extracranial carotid artery occlusive lesions. These data highlight the importance of prompt assessment of intracranial artery lesions in patients with TIA.

  9. Ruptured visceral artery aneurysms.

    PubMed

    Chiaradia, M; Novelli, L; Deux, J-F; Tacher, V; Mayer, J; You, K; Djabbari, M; Luciani, A; Rahmouni, A; Kobeiter, H

    2015-01-01

    Visceral artery aneurysms are rare but their estimated mortality due to rupture ranges between 25 and 70%. Treatment of visceral artery aneurysm rupture is usually managed by interventional radiology. Specific embolization techniques depend on the location, affected organ, locoregional arterial anatomy, and interventional radiologist skill. The success rate following treatment by interventional radiology is greater than 90%. The main complication is recanalization of the aneurysm, showing the importance of post-therapeutic monitoring, which should preferably be performed using MR imaging. PMID:26054246

  10. Contribution of cardiovascular magnetic resonance in the evaluation of coronary arteries.

    PubMed

    Mavrogeni, Sophie; Markousis-Mavrogenis, George; Kolovou, Genovefa

    2014-10-26

    Cardiovascular magnetic resonance (CMR) allows the nonradiating assessment of coronary arteries; to achieve better image quality cardiorespiratory artefacts should be corrected. Coronary MRA (CMRA) at the moment is indicated only for the detection of abnormal coronary origin, coronary artery ectasia and/or aneurysms (class?I?indication) and coronary bypass grafts (class II indication). CMRA utilisation for coronary artery disease is not yet part of clinical routine. However, the lack of radiation is of special value for the coronary artery evaluation in children and women. CMRA can assess the proximal part of coronary arteries in almost all cases. The best results have been observed in the evaluation of the left anterior descending and the right coronary artery, while the left circumflex, which is located far away from the coil elements, is frequently imaged with reduced quality, compared to the other two. Different studies detected an increase in wall thickness of the coronaries in patients with type?I?diabetes and abnormal renal function. Additionally, the non-contrast enhanced T1-weighed images detected the presence of thrombus in acute myocardial infarction. New techniques using delayed gadolinium enhanced imaging promise the direct visualization of inflamed plaques in the coronary arteries. The major advantage of CMR is the potential of an integrated protocol offering assessment of coronary artery anatomy, cardiac function, inflammation and stress perfusion-fibrosis in the same study, providing an individualized clinical profile of patients with heart disease. PMID:25349650

  11. Contribution of cardiovascular magnetic resonance in the evaluation of coronary arteries

    PubMed Central

    Mavrogeni, Sophie; Markousis-Mavrogenis, George; Kolovou, Genovefa

    2014-01-01

    Cardiovascular magnetic resonance (CMR) allows the nonradiating assessment of coronary arteries; to achieve better image quality cardiorespiratory artefacts should be corrected. Coronary MRA (CMRA) at the moment is indicated only for the detection of abnormal coronary origin, coronary artery ectasia and/or aneurysms (class?I?indication) and coronary bypass grafts (class II indication). CMRA utilisation for coronary artery disease is not yet part of clinical routine. However, the lack of radiation is of special value for the coronary artery evaluation in children and women. CMRA can assess the proximal part of coronary arteries in almost all cases. The best results have been observed in the evaluation of the left anterior descending and the right coronary artery, while the left circumflex, which is located far away from the coil elements, is frequently imaged with reduced quality, compared to the other two. Different studies detected an increase in wall thickness of the coronaries in patients with type?I?diabetes and abnormal renal function. Additionally, the non-contrast enhanced T1-weighed images detected the presence of thrombus in acute myocardial infarction. New techniques using delayed gadolinium enhanced imaging promise the direct visualization of inflamed plaques in the coronary arteries. The major advantage of CMR is the potential of an integrated protocol offering assessment of coronary artery anatomy, cardiac function, inflammation and stress perfusion-fibrosis in the same study, providing an individualized clinical profile of patients with heart disease. PMID:25349650

  12. Influence of Chronic Kidney Disease on Physical Function and Quality of Life in Patients after Coronary Artery Bypass Grafting

    PubMed Central

    Kuo, Yueh-Ting; Chiu, Kuan-Ming; Tsang, Yuk-Ming; Chiu, Cheng-Ming; Chien, Meng-Yueh

    2015-01-01

    Aims The purposes of this study were (1) to compare body composition, physical function, and quality of life (QOL) between patients after coronary artery bypass grafting (CABG) with and without chronic kidney disease (CKD) and (2) to analyze the factors associated with physical function and QOL domains in these patients. Methods Thirty male post-CABG patients with CKD and 30 matched controls were recruited. All subjects underwent dual-energy X-ray absorptiometry for body composition evaluation. Physical function tests included the grip strength test, 30-second chair stand test (30CST), and 6-min walk test (6MWT). Physical activity and QOL were assessed using the long form of the International Physical Activity Questionnaire and the World Health Organization Quality of Life Instrument (WHOQOL)-BREF, respectively. Results Post-CABG patients with CKD exhibited a lower arm lean mass and higher percent leg fat mass than those without CKD (p < 0.05). The patients with CKD also had lower 30CST scores, 6MWT distances, and QOL domain of social relationships scores than those without CKD after adjusting for covariates (p < 0.05). If NYHA class was considered in the model, NYHA class became the most important factor associated with 6MWT distances (? = ?0.647, p < 0.001) and the QOL domains of psychological health (? = ?0.285, p = 0.027) and environment (? = ?0.406, p = 0.001). Conclusion Post-CABG patients with CKD had worse body composition, physical function, and QOL than those without CKD, and this might be associated with a worse NYHA class. PMID:26648940

  13. Stress Imaging May Be Overused in Medicare Patients With Stable Coronary Artery Disease

    MedlinePLUS

    ... January 2013 Events Newsroom Research Activities, October 2013 Stress imaging may be overused in Medicare patients with ... for long-term adverse events after coronary stenting Stress imaging may be overused in Medicare patients with ...

  14. Task-based measures of image quality and their relation to radiation dose and patient risk

    NASA Astrophysics Data System (ADS)

    Barrett, Harrison H.; Myers, Kyle J.; Hoeschen, Christoph; Kupinski, Matthew A.; Little, Mark P.

    2015-01-01

    The theory of task-based assessment of image quality is reviewed in the context of imaging with ionizing radiation, and objective figures of merit (FOMs) for image quality are summarized. The variation of the FOMs with the task, the observer and especially with the mean number of photons recorded in the image is discussed. Then various standard methods for specifying radiation dose are reviewed and related to the mean number of photons in the image and hence to image quality. Current knowledge of the relation between local radiation dose and the risk of various adverse effects is summarized, and some graphical depictions of the tradeoffs between image quality and risk are introduced. Then various dose-reduction strategies are discussed in terms of their effect on task-based measures of image quality.

  15. Image quality assessment using multi-method fusion.

    PubMed

    Liu, Tsung-Jung; Lin, Weisi; Kuo, C-C Jay

    2013-05-01

    A new methodology for objective image quality assessment (IQA) with multi-method fusion (MMF) is presented in this paper. The research is motivated by the observation that there is no single method that can give the best performance in all situations. To achieve MMF, we adopt a regression approach. The new MMF score is set to be the nonlinear combination of scores from multiple methods with suitable weights obtained by a training process. In order to improve the regression results further, we divide distorted images into three to five groups based on the distortion types and perform regression within each group, which is called "context-dependent MMF" (CD-MMF). One task in CD-MMF is to determine the context automatically, which is achieved by a machine learning approach. To further reduce the complexity of MMF, we perform algorithms to select a small subset from the candidate method set. The result is very good even if only three quality assessment methods are included in the fusion process. The proposed MMF method using support vector regression is shown to outperform a large number of existing IQA methods by a significant margin when being tested in six representative databases. PMID:23288335

  16. Blind Image Quality Assessment using Semi-supervised Rectifier Networks Huixuan Tang

    E-print Network

    Toronto, University of

    and machine learning to model perceptual image quality. Such methods first extract hand-crafted features fromBlind Image Quality Assessment using Semi-supervised Rectifier Networks Huixuan Tang University human provided quality scores with machine learning to learn a measure. The biggest hurdles

  17. IMAGE QUALITY AND VISUAL ATTENTION INTERACTIONS: TOWARDS A MORE RELIABLE ANALYSIS IN THE SALIENCY SPACE

    E-print Network

    perception can be greatly beneficial for the design of effective objective quality metrics. Subjective the design of image enhancement algorithms and their related objective visual quality metrics in particularIMAGE QUALITY AND VISUAL ATTENTION INTERACTIONS: TOWARDS A MORE RELIABLE ANALYSIS IN THE SALIENCY

  18. Image Quality, Tissue Heating, and Frame Rate Trade-offs in Acoustic Radiation Force Impulse Imaging

    PubMed Central

    Bouchard, Richard R.; Dahl, Jeremy J.; Hsu, stephen J.; Palmeri, Mark L.; Trahey, Gregg E.

    2013-01-01

    The real-time application of acoustic radiation force impulse (ARFI) imaging requires both short acquisition times for a single ARFI image and repeated acquisition of these frames. Due to the high energy of pulses required to generate appreciable radiation force, however, repeated acquisitions could result in substantial transducer face and tissue heating. We describe and evaluate several novel beam sequencing schemes which, along with parallel-receive acquisition, are designed to reduce acquisition time and heating. These techniques reduce the total number of radiation force impulses needed to generate an image and minimize the time between successive impulses. We present qualitative and quantitative analyses of the trade-offs in image quality resulting from the acquisition schemes. Results indicate that these techniques yield a significant improvement in frame rate with only moderate decreases in image quality. Tissue and transducer face heating resulting from these schemes is assessed through finite element method modeling and thermocouple measurements. Results indicate that heating issues can be mitigated by employing ARFI acquisition sequences that utilize the highest track-to-excitation ratio possible. PMID:19213633

  19. Image-based computational simulation of sub-endothelial LDL accumulation in a human right coronary artery.

    PubMed

    Nouri, Mohammad; Jalali, Farhang; Karimi, Gholamreza; Zarrabi, Khalil

    2015-07-01

    Accumulation of low density lipoproteins (LDL) in the vessel wall is suggested as the initiator of atherosclerosis and coronary stenosis. This process is associated with the performance of endothelium layer that regulates entering of macromolecules to the vessel wall. Therefore, the present study aims to investigate sub-endothelial accumulation of LDL molecules in a coronary tree and predict atherosclerosis prone sites. Non-Newtonian blood flow is simulated for normal and hypertensive conditions through the lumen of a right coronary artery reconstructed from computed tomography (CT) images. A three-pore model is implemented as the endothelium boundary condition and hence, plasma flow and LDL transport are simulated within the arterial wall. Based on the pore model, endothelium pathways divide into normal junctions, vesicles and leaky junctions. Most of LDL molecules pass through the leaky junctions that arise at locations with low wall shear stress (WSS). Results indicate that increase in the number of leaky junctions at branch points with low WSS can lead to both elevated levels of sub-endothelial LDL accumulation and atherosclerosis risk. Findings reveal that at the branch points with disturbed flow, sub-endothelial concentration of LDL for the hypertensive condition is higher than the normal condition, however for the rest of regions with uniform geometry and unidirectional flow, this is reversed. Comparisons of non-Newtonian and Newtonian flows show mean increases of 34% and 13% in the sub-endothelial concentrations of Newtonian flows during the normal and hypertensive conditions, respectively. PMID:25957745

  20. Prognostic importance of silent myocardial ischemia detected by intravenous dipyridamole thallium myocardial imaging in asymptomatic patients with coronary artery disease

    SciTech Connect

    Younis, L.T.; Byers, S.; Shaw, L.; Barth, G.; Goodgold, H.; Chaitman, B.R. )

    1989-12-01

    One hundred seven asymptomatic patients who underwent intravenous dipyridamole thallium imaging were evaluated to determine prognostic indicators of subsequent cardiac events over an average follow-up period of 14 +/- 10 months. Univariate analysis of 18 clinical, scintigraphic and angiographic variables revealed that a reversible thallium defect, a combined fixed and reversible thallium defect, number of segmental thallium defects and extent of coronary artery disease were significant predictors of subsequent cardiac events. Of the 13 patients who died or had a nonfatal infarction, 12 had a reversible thallium defect. Stepwise logistic regression analysis selected a reversible thallium defect as the only significant predictor of cardiac events. When death or myocardial infarction was the outcome variable, a combined fixed and reversible thallium defect was the only predictor of outcome. In patients without previous myocardial infarction, the cardiac event rate was significantly greater in those with an abnormal versus normal thallium scan (55% versus 12%, p less than 0.001). Thus, intravenous dipyridamole thallium scintigraphy is a useful noninvasive test to risk stratify asymptomatic patients with coronary artery disease. A reversible thallium defect most likely indicates silent myocardial ischemia in a sizable fraction of patients in this clinical subset and is associated with an unfavorable prognosis.

  1. Quality Enhancement and Nerve Fibre Layer Artefacts Removal in Retina Fundus Images by Off Axis Imaging

    SciTech Connect

    Giancardo, Luca; Meriaudeau, Fabrice; Karnowski, Thomas Paul; Li, Yaquin; Tobin Jr, Kenneth William; Chaum, Edward

    2011-01-01

    Retinal fundus images acquired with non-mydriatic digital fundus cameras are a versatile tool for the diagnosis of various retinal diseases. Because of the ease of use of newer camera models and their relative low cost, these cameras are employed worldwide by retina specialists to diagnose diabetic retinopathy and other degenerative diseases. Even with relative ease of use, the images produced by these systems sometimes suffer from reflectance artefacts mainly due to the nerve fibre layer (NFL) or other camera lens related reflections. We propose a technique that employs multiple fundus images acquired from the same patient to obtain a single higher quality image without these reflectance artefacts. The removal of bright artefacts, and particularly of NFL reflectance, can have great benefits for the reduction of false positives in the detection of retinal lesions such as exudate, drusens and cotton wool spots by automatic systems or manual inspection. If enough redundant information is provided by the multiple images, this technique also compensates for a suboptimal illumination. The fundus images are acquired in straightforward but unorthodox manner, i.e. the stare point of the patient is changed between each shot but the camera is kept fixed. Between each shot, the apparent shape and position of all the retinal structures that do not exhibit isotropic reflectance (e.g. bright artefacts) change. This physical effect is exploited by our algorithm in order to extract the pixels belonging to the inner layers of the retina, hence obtaining a single artefacts-free image.

  2. Open source database of images DEIMOS: extension for large-scale subjective image quality assessment

    NASA Astrophysics Data System (ADS)

    Vítek, Stanislav

    2014-09-01

    DEIMOS (Database of Images: Open Source) is an open-source database of images and video sequences for testing, verification and comparison of various image and/or video processing techniques such as compression, reconstruction and enhancement. This paper deals with extension of the database allowing performing large-scale web-based subjective image quality assessment. Extension implements both administrative and client interface. The proposed system is aimed mainly at mobile communication devices, taking into account advantages of HTML5 technology; it means that participants don't need to install any application and assessment could be performed using web browser. The assessment campaign administrator can select images from the large database and then apply rules defined by various test procedure recommendations. The standard test procedures may be fully customized and saved as a template. Alternatively the administrator can define a custom test, using images from the pool and other components, such as evaluating forms and ongoing questionnaires. Image sequence is delivered to the online client, e.g. smartphone or tablet, as a fully automated assessment sequence or viewer can decide on timing of the assessment if required. Environmental data and viewing conditions (e.g. illumination, vibrations, GPS coordinates, etc.), may be collected and subsequently analyzed.

  3. Optimization of HVS-based objective image quality assessment with eye tracking

    NASA Astrophysics Data System (ADS)

    Fliegel, Karel

    2008-08-01

    In this paper, we present an approach to predict perceived quality of compressed images while incorporating real visual attention coordinates. Information about the visual attention is not usually taken into account in image quality assessment models. The idea of implementing gaze information into the image quality assessment system lies in that the artefacts are more disturbing to human observer in the region with higher saliency than in other parts of an image. Impact of the re¬gion of interest on estimation accuracy of a simple image quality metric is investigated. The gaze coordinates were calculated using calibrated electro-oculogram records of human observers while watching a number of test images. The same images were used for subjective image quality assessment. Obtained mean opinion scores of perceived image quality and eye tracking data were used to verify potential improvement of assessment accuracy for a simple image quality metric. Based on the proven effect, our previously developed system for still image quality assessment has been adapted while utilizing information about the visual attention. The potential performance improvement of existing image coding while incorporating the spatially adaptive HVS is discussed.

  4. 3D-FIESTA Magnetic Resonance Angiography Fusion Imaging of Distal Segment of Occluded Middle Cerebral Artery.

    PubMed

    Kuribara, Tomoyoshi; Haraguchi, Koichi; Ogane, Kazumi; Matsuura, Nobuki; Ito, Takeo

    2015-10-15

    Middle cerebral artery (MCA) occlusion was examined with basi-parallel anatomical scanning (BPAS) using three-dimensional fast imaging employing steady-state acquisition (3D-FIESTA), and 3D-FIESTA and magnetic resonance angiography (MRA) fusion images were created. We expected that an incidence of hemorrhagic complications due to vessel perforations would be decreased by obtaining vascular information beyond the occlusion and thus acute endovascular revascularization could be performed using such techniques. We performed revascularization for acute MCA occlusion for five patients who were admitted in our hospital from October 2012 to October 2014. Patients consisted of 1 man and 4 women with a mean age of 76.2 years (range: 59-86 years). Fusion images were created from three-dimensional time of flight (3D-TOF) MRA and 3D-FIESTA with phase cycling (3D-FIESTA-C). Then thrombectomy was performed in all the 5 patients. Merci retriever to 1 patient, Penumbra system to 1, urokinase infusion to 2, and Solitaire to 1 using such techniques. In all cases, a 3D-FIESTA-MRA fusion imaging could depict approximately clear vascular information to at least the M3 segment beyond the occlusion. And each acute revascularization was able to perform smoothly using these imaging techniques. In all cases, there was no symptomatic hemorrhagic complication. It showed that 3D-FIESTA MRA fusion imaging technique could obtain vascular information beyond the MCA occlusion. In this study, no symptomatic hemorrhagic complications were detected. It could imply that such techniques were useful not only to improve treatment efficiency but also to reduce the risk of development of hemorrhagic complications caused by vessel perforations in acute revascularization. PMID:26369877

  5. Advanced Imaging Magazine, January 2000, pp. 69-70 Firewire Untethered: High-Quality Images for Notebook Computers

    E-print Network

    for Notebook Computers Iwan Ulrich and Illah Nourbakhsh The Robotics Institute, Carnegie Mellon University 5000 for acquiring high-quality color images in real-time with a regular notebook computer, even though a high-quality color image acquisition system for notebook computers would open the doors for a wide array of portable

  6. A widefield fluorescence microscope with a linear image sensor for image cytometry of biospecimens: Considerations for image quality optimization

    NASA Astrophysics Data System (ADS)

    Hutcheson, Joshua A.; Majid, Aneeka A.; Powless, Amy J.; Muldoon, Timothy J.

    2015-09-01

    Linear image sensors have been widely used in numerous research and industry applications to provide continuous imaging of moving objects. Here, we present a widefield fluorescence microscope with a linear image sensor used to image translating objects for image cytometry. First, a calibration curve was characterized for a custom microfluidic chamber over a span of volumetric pump rates. Image data were also acquired using 15 ?m fluorescent polystyrene spheres on a slide with a motorized translation stage in order to match linear translation speed with line exposure periods to preserve the image aspect ratio. Aspect ratios were then calculated after imaging to ensure quality control of image data. Fluorescent beads were imaged in suspension flowing through the microfluidics chamber being pumped by a mechanical syringe pump at 16 ?l min-1 with a line exposure period of 150 ?s. The line period was selected to acquire images of fluorescent beads with a 40 dB signal-to-background ratio. A motorized translation stage was then used to transport conventional glass slides of stained cellular biospecimens. Whole blood collected from healthy volunteers was stained with 0.02% (w/v) proflavine hemisulfate was imaged to highlight leukocyte morphology with a 1.56 mm × 1.28 mm field of view (1540 ms total acquisition time). Oral squamous cells were also collected from healthy volunteers and stained with 0.01% (w/v) proflavine hemisulfate to demonstrate quantifiable subcellular features and an average nuclear to cytoplasmic ratio of 0.03 (n = 75), with a resolution of 0.31 ?m pixels-1.

  7. Beyond image quality: designing engaging interactions with digital products

    NASA Astrophysics Data System (ADS)

    de Ridder, Huib; Rozendaal, Marco C.

    2008-02-01

    Ubiquitous computing (or Ambient Intelligence) promises a world in which information is available anytime anywhere and with which humans can interact in a natural, multimodal way. In such world, perceptual image quality remains an important criterion since most information will be displayed visually, but other criteria such as enjoyment, fun, engagement and hedonic quality are emerging. This paper deals with engagement, the intrinsically enjoyable readiness to put more effort into exploring and/or using a product than strictly required, thus attracting and keeping user's attention for a longer period of time. The impact of the experienced richness of an interface, both visually and degree of possible manipulations, was investigated in a series of experiments employing game-like user interfaces. This resulted in the extension of an existing conceptual framework relating engagement to richness by means of two intermediating variables, namely experienced challenge and sense of control. Predictions from this revised framework are evaluated against results of an earlier experiment assessing the ergonomic and hedonic qualities of interactive media. Test material consisted of interactive CD-ROM's containing presentations of three companies for future customers.

  8. Image quality optimization and evaluation of linearly mixed images in dual-source, dual-energy CT.

    PubMed

    Yu, Lifeng; Primak, Andrew N; Liu, Xin; McCollough, Cynthia H

    2009-03-01

    In dual-source dual-energy CT, the images reconstructed from the low- and high-energy scans (typically at 80 and 140 kV, respectively) can be mixed together to provide a single set of nonmaterial-specific images for the purpose of routine diagnostic interpretation. Different from the material-specific information that may be obtained from the dual-energy scan data, the mixed images are created with the purpose of providing the interpreting physician a single set of images that have an appearance similar to that in single-energy images acquired at the same total radiation dose. In this work, the authors used a phantom study to evaluate the image quality of linearly mixed images in comparison to single-energy CT images, assuming the same total radiation dose and taking into account the effect of patient size and the dose partitioning between the low-and high-energy scans. The authors first developed a method to optimize the quality of the linearly mixed images such that the single-energy image quality was compared to the best-case image quality of the dual-energy mixed images. Compared to 80 kV single-energy images for the same radiation dose, the iodine CNR in dual-energy mixed images was worse for smaller phantom sizes. However, similar noise and similar or improved iodine CNR relative to 120 kV images could be achieved for dual-energy mixed images using the same total radiation dose over a wide range of patient sizes (up to 45 cm lateral thorax dimension). Thus, for adult CT practices, which primarily use 120 kV scanning, the use of dual-energy CT for the purpose of material-specific imaging can also produce a set of non-material-specific images for routine diagnostic interpretation that are of similar or improved quality relative to single-energy 120 kV scans. PMID:19378762

  9. Image quality optimization and evaluation of linearly mixed images in dual-source, dual-energy CT

    SciTech Connect

    Yu Lifeng; Primak, Andrew N.; Liu Xin; McCollough, Cynthia H.

    2009-03-15

    In dual-source dual-energy CT, the images reconstructed from the low- and high-energy scans (typically at 80 and 140 kV, respectively) can be mixed together to provide a single set of non-material-specific images for the purpose of routine diagnostic interpretation. Different from the material-specific information that may be obtained from the dual-energy scan data, the mixed images are created with the purpose of providing the interpreting physician a single set of images that have an appearance similar to that in single-energy images acquired at the same total radiation dose. In this work, the authors used a phantom study to evaluate the image quality of linearly mixed images in comparison to single-energy CT images, assuming the same total radiation dose and taking into account the effect of patient size and the dose partitioning between the low-and high-energy scans. The authors first developed a method to optimize the quality of the linearly mixed images such that the single-energy image quality was compared to the best-case image quality of the dual-energy mixed images. Compared to 80 kV single-energy images for the same radiation dose, the iodine CNR in dual-energy mixed images was worse for smaller phantom sizes. However, similar noise and similar or improved iodine CNR relative to 120 kV images could be achieved for dual-energy mixed images using the same total radiation dose over a wide range of patient sizes (up to 45 cm lateral thorax dimension). Thus, for adult CT practices, which primarily use 120 kV scanning, the use of dual-energy CT for the purpose of material-specific imaging can also produce a set of non-material-specific images for routine diagnostic interpretation that are of similar or improved quality relative to single-energy 120 kV scans.

  10. Comparison of no-reference image quality assessment machine learning-based algorithms on compressed images

    NASA Astrophysics Data System (ADS)

    Charrier, Christophe; Saadane, AbdelHakim; Fernandez-Maloigne, Christine

    2015-01-01

    No-reference image quality metrics are of fundamental interest as they can be embedded in practical applications. The main goal of this paper is to perform a comparative study of seven well known no-reference learning-based image quality algorithms. To test the performance of these algorithms, three public databases are used. As a first step, the trial algorithms are compared when no new learning is performed. The second step investigates how the training set influences the results. The Spearman Rank Ordered Correlation Coefficient (SROCC) is utilized to measure and compare the performance. In addition, an hypothesis test is conducted to evaluate the statistical significance of performance of each tested algorithm.

  11. Digital Image Processing Applied To Quality Assurance In Mineral Industry

    NASA Astrophysics Data System (ADS)

    Hamrouni, Zouheir; Ayache, Alain; Krey, Charlie J.

    1989-03-01

    In this paper , we bring forward an application of vision in the domain of quality assurance in mineral industry of talc. By using image processing and computer vision means, the proposed real time whiteness captor system intends: - to inspect the whiteness of grinded product, - to manage the mixing of primary talcs before grinding, in order to obtain a final product with predetermined whiteness. The system uses the robotic CCD microcamera MICAM (designed by our laboratory and presently manufactured), a micro computer system based on Motorola 68020 and real time image processing boards. It has the industrial following specifications: - High reliability - Whiteness is determined with a 0.3% precision on a scale of 25 levels. Because of the expected precision, we had to study carefully the lighting system, the type of image captor and associated electronics. The first developped softwares are able to process the withness of talcum powder; then we have conceived original algorithms to control withness of rough talc taking into account texture and shadows. The processing times of these algorithms are completely compatible with industrial rates. This system can be applied to other domains where high precision reflectance captor is needed: industry of paper, paints, ...

  12. A no-reference quality assessment algorithm for JPEG2000-compressed images based on local sharpness

    NASA Astrophysics Data System (ADS)

    Vu, Phong V.; Chandler, Damon M.

    2013-01-01

    In this paper, we present a no-reference quality assessment algorithm for JPEG2000-compressed images called EDIQ (EDge-based Image Quality). The algorithm works based on the assumption that the quality of JPEG2000- compressed images can be evaluated by separately computing the quality of the edge/near-edge regions and the non-edge regions where no edges are present. EDIQ first separates the input image into edge/near-edge regions and non-edge regions by applying Canny edge detection and edge-pixel dilation. Our previous sharpness algorithm, FISH [Vu and Chandler, 2012], is used to generate a sharpness map. The part of the sharpness map corresponding to the non-edge regions is collapsed by using root mean square to yield the image quality index of the non-edge regions. The other part of the sharpness map, which corresponds to the edge/near-edge regions, is weighted by the local RMS contrast and the local slope of magnitude spectrum to yield an enhanced quality map, which is then collapsed into the quality index of the edge/near-edge regions. These two indices are combined by a geometric mean to yield a quality indicator of the input image. Testing on the JPEG2000-compressed subsets of four different image-quality databases demonstrate that EDIQ is competitive with other no-reference image quality algorithms on JPEG2000-compressed images.

  13. The Impact of Different Levels of Adaptive Iterative Dose Reduction 3D on Image Quality of 320-Row Coronary CT Angiography: A Clinical Trial

    PubMed Central

    Feger, Sarah; Rief, Matthias; Zimmermann, Elke; Martus, Peter; Schuijf, Joanne Désirée; Blobel, Jörg; Richter, Felicitas; Dewey, Marc

    2015-01-01

    Purpose The aim of this study was the systematic image quality evaluation of coronary CT angiography (CTA), reconstructed with the 3 different levels of adaptive iterative dose reduction (AIDR 3D) and compared to filtered back projection (FBP) with quantum denoising software (QDS). Methods Standard-dose CTA raw data of 30 patients with mean radiation dose of 3.2 ± 2.6 mSv were reconstructed using AIDR 3D mild, standard, strong and compared to FBP/QDS. Objective image quality comparison (signal, noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), contour sharpness) was performed using 21 measurement points per patient, including measurements in each coronary artery from proximal to distal. Results Objective image quality parameters improved with increasing levels of AIDR 3D. Noise was lowest in AIDR 3D strong (p?0.001 at 20/21 measurement points; compared with FBP/QDS). Signal and contour sharpness analysis showed no significant difference between the reconstruction algorithms for most measurement points. Best coronary SNR and CNR were achieved with AIDR 3D strong. No loss of SNR or CNR in distal segments was seen with AIDR 3D as compared to FBP. Conclusions On standard-dose coronary CTA images, AIDR 3D strong showed higher objective image quality than FBP/QDS without reducing contour sharpness. Trial Registration Clinicaltrials.gov NCT00967876 PMID:25945924

  14. Design of a practical model-observer-based image quality assessment method for CT imaging systems

    NASA Astrophysics Data System (ADS)

    Tseng, Hsin-Wu; Fan, Jiahua; Cao, Guangzhi; Kupinski, Matthew A.; Sainath, Paavana

    2014-03-01

    The channelized Hotelling observer (CHO) is a powerful method for quantitative image quality evaluations of CT systems and their image reconstruction algorithms. It has recently been used to validate the dose reduction capability of iterative image-reconstruction algorithms implemented on CT imaging systems. The use of the CHO for routine and frequent system evaluations is desirable both for quality assurance evaluations as well as further system optimizations. The use of channels substantially reduces the amount of data required to achieve accurate estimates of observer performance. However, the number of scans required is still large even with the use of channels. This work explores different data reduction schemes and designs a new approach that requires only a few CT scans of a phantom. For this work, the leave-one-out likelihood (LOOL) method developed by Hoffbeck and Landgrebe is studied as an efficient method of estimating the covariance matrices needed to compute CHO performance. Three different kinds of approaches are included in the study: a conventional CHO estimation technique with a large sample size, a conventional technique with fewer samples, and the new LOOL-based approach with fewer samples. The mean value and standard deviation of area under ROC curve (AUC) is estimated by shuffle method. Both simulation and real data results indicate that an 80% data reduction can be achieved without loss of accuracy. This data reduction makes the proposed approach a practical tool for routine CT system assessment.

  15. Hierarchical Learning for Tubular Structure Parsing in Medical Imaging: A Study on Coronary Arteries Using 3D CT Angiography

    E-print Network

    Chandy, John A.

    Arteries Using 3D CT Angiography Le Lu Jinbo Bi Shipeng Yu Zhigang Peng Arun Krishnan Xiang Sean Zhou CAD.lastname@siemens.com Abstract Automatic coronary artery centerline extraction from 3D CT Angiography (CTA) has significant is dominated by segmenting the complete coronary artery system as trees by computer. Though the labeling

  16. IEEE TRANSACTIONS ON MEDICAL IMAGING --FINAL MANUSCRIPT 2004-0117 1 Interactive Virtual Endoscopy in Coronary Arteries

    E-print Network

    Wahle, Andreas

    in Coronary Arteries based on Multi-Modality Fusion Andreas Wahle, Senior Member, IEEE, Mark E. Olszewski-independent virtual endoscopy in human coronary arteries is presented in this pa- per. It incorporates previously results in a three- or four-dimensional (3-D/4-D) model of a coronary artery, specifically of its lumen

  17. A three-dimensional statistical approach to improved image quality for multislice helical CT

    E-print Network

    development, superior image quality combined with advancements in computing technol- ogy make IR techniques, and large organ coverage. Those acquisition trajectories produce projection measurements that pass obliquely

  18. A Novel Cause of Acute Coronary Syndrome Due to Dynamic Extrinsic Coronary Artery Compression by a Rib Exostosis: Multimodality Imaging Diagnosis.

    PubMed

    Rodrigues, Jonathan C L; Mathias, Helen C; Lyen, Stephen M; Mcalindon, Elisa; Bucciarelli-Ducci, Chiara; Batchelor, Timothy J P; Hamilton, Mark C K; Manghat, Nathan E

    2015-10-01

    We report a case of acute coronary syndrome secondary to intermittent extrinsic compression of the left anterior descending coronary artery by inward-pointing rib exostosis in an 18-year-old woman during forceful repeated expiration in labour. The diagnosis was achieved using multimodality noninvasive cardiac imaging. In particular, we demonstrated the novel role of expiratory-phase cardiac computed tomography in confirming the anatomical relationship of the bony exostosis to the left anterior descending coronary artery. The case reminds us the heart and mediastinum move dynamically, relative to the bony thorax, throughout the respiratory cycle, and that changes in cardiac physiology in pregnancy may become pathological. PMID:26255213

  19. The image quality of ion computed tomography at clinical imaging dose levels

    SciTech Connect

    Hansen, David C.; Bassler, Niels; Sørensen, Thomas Sangild; Seco, Joao

    2014-11-01

    Purpose: Accurately predicting the range of radiotherapy ions in vivo is important for the precise delivery of dose in particle therapy. Range uncertainty is currently the single largest contribution to the dose margins used in planning and leads to a higher dose to normal tissue. The use of ion CT has been proposed as a method to improve the range uncertainty and thereby reduce dose to normal tissue of the patient. A wide variety of ions have been proposed and studied for this purpose, but no studies evaluate the image quality obtained with different ions in a consistent manner. However, imaging doses ion CT is a concern which may limit the obtainable image quality. In addition, the imaging doses reported have not been directly comparable with x-ray CT doses due to the different biological impacts of ion radiation. The purpose of this work is to develop a robust methodology for comparing the image quality of ion CT with respect to particle therapy, taking into account different reconstruction methods and ion species. Methods: A comparison of different ions and energies was made. Ion CT projections were simulated for five different scenarios: Protons at 230 and 330 MeV, helium ions at 230 MeV/u, and carbon ions at 430 MeV/u. Maps of the water equivalent stopping power were reconstructed using a weighted least squares method. The dose was evaluated via a quality factor weighted CT dose index called the CT dose equivalent index (CTDEI). Spatial resolution was measured by the modulation transfer function. This was done by a noise-robust fit to the edge spread function. Second, the image quality as a function of the number of scanning angles was evaluated for protons at 230 MeV. In the resolution study, the CTDEI was fixed to 10 mSv, similar to a typical x-ray CT scan. Finally, scans at a range of CTDEI’s were done, to evaluate dose influence on reconstruction error. Results: All ions yielded accurate stopping power estimates, none of which were statistically different from the ground truth image. Resolution (as defined by the modulation transfer function = 10% point) was the best for the helium ions (18.21 line pairs/cm) and worst for the lower energy protons (9.37 line pairs/cm). The weighted quality factor for the different ions ranged from 1.23 for helium to 2.35 for carbon ions. For the angle study, a sharp increase in absolute error was observed below 45 distinct angles, giving the impression of a threshold, rather than smooth, limit to the number of angles. Conclusions: The method presented for comparing various ion CT modalities is feasible for practical use. While all studied ions would improve upon x-ray CT for particle range estimation, helium appears to give the best results and deserves further study for imaging.

  20. Poor Sleep Quality in Patients after Coronary Artery Bypass Graft Surgery: An Intervention Study Using the PRECEDE-PROCEED Model

    PubMed Central

    Ranjbaran, Soheila; Dehdari, Tahereh; Sadeghniiat-Haghighi, Khosro; Majdabadi, Mahmood Mahmoodi

    2015-01-01

    Abstract Background: Poor sleep quality (SQ) is common among patients after coronary artery bypass graft surgery (CABG). This study attempted to determine the status of SQ following an intervention based on the PRECEDE-PROCEED model in patients with poor SQ after CABG. Methods: This study was a randomized clinical trial. The study sample, including 100 patients referred to the Cardiac Rehabilitation Clinic of Tehran Heart Center, was assigned either to the intervention (recipient of exercise and lifestyle training plus designed intervention based on the PRECEDE-PROCEED model) or to the control group (recipient of exercise and lifestyle training). Eight training sessions over 8 weeks were conducted for the intervention group. Predisposing, enabling, and reinforcing factors as well as social support and SQ were measured in the intervention group before and one month after the intervention and compared to those in the control group at the same time points. Results: The mean age of the patients in the intervention (24% women) and control (24% women) groups was 59.3 ± 7.3 and 59.5 ± 9.3 years, respectively. The results showed that the mean scores of SQ (p value < 0.001), knowledge (p value < 0.001), beliefs (p value < 0.001), sleep self-efficacy (p value < 0.001), enabling factors (p value < 0.001), reinforcing factors (p value < 0.001), and social support (p value < 0.001) were significantly different between the intervention and control groups after the intervention. Conclusion: Adding an intervention based on the PRECEDE-PROCEED model to the cardiac rehabilitation program may further improve the SQ of patients. PMID:26157457

  1. Non-linear imaging and characterization of atherosclerotic arterial tissue using combined two photon fluorescence, second-harmonic generation and CARS microscopy

    NASA Astrophysics Data System (ADS)

    Cicchi, Riccardo; Matthäus, Christian; Meyer, Tobias; Lattermann, Annika; Dietzek, Benjamin; Brehm, Bernhard R.; Popp, Jürgen; Pavone, Francesco S.

    2014-02-01

    Atherosclerosis is among the most widespread cardiovascular diseases and one of the leading cause of death in the Western World. Characterization of arterial tissue in atherosclerotic condition is extremely interesting from the diagnostic point of view. Routinely used diagnostic methods, such as histopathological examination, are limited to morphological analysis of the examined tissues, whereas an exhaustive characterization requires a morpho-functional approach. Multimodal non-linear microscopy has the potential to bridge this gap by providing morpho-functional information on the examined tissues in a label-free way. Here we employed multiple non-linear microscopy techniques, including CARS, TPF, and SHG to provide intrinsic optical contrast from various tissue components in both arterial wall and atherosclerotic plaques. CARS and TPF microscopy were used to respectively image lipid depositions within plaques and elastin in the arterial wall. Cholesterol deposition in the lumen and collagen in the arterial wall were selectively imaged by SHG microscopy and distinguished by forward-backward SHG ratio. Image pattern analysis allowed characterizing collagen organization in different tissue regions. Different values of fiber mean size, distribution and anisotropy are calculated for lumen and media prospectively allowing for automated classification of atherosclerotic lesions. The presented method represents a promising diagnostic tool for evaluating atherosclerotic tissue and has the potential to find a stable place in clinical setting as well as to be applied in vivo in the near future.

  2. Learning a channelized observer for image quality assessment.

    PubMed

    Brankov, Jovan G; Yang, Yongyi; Wei, Liyang; El Naqa, Issam; Wernick, Miles N

    2009-07-01

    It is now widely accepted that image quality should be evaluated using task-based criteria, such as human-observer performance in a lesion-detection task. The channelized Hotelling observer (CHO) has been widely used as a surrogate for human observers in evaluating lesion detectability. In this paper, we propose that the problem of developing a numerical observer can be viewed as a system-identification or supervised-learning problem, in which the goal is to identify the unknown system of the human observer. Following this approach, we explore the possibility of replacing the Hotelling detector within the CHO with an algorithm that learns the relationship between measured channel features and human observer scores. Specifically, we develop a channelized support vector machine (CSVM) which we compare to the CHO in terms of its ability to predict human-observer performance. In the examples studied, we find that the CSVM is better able to generalize to unseen images than the CHO, and therefore may represent a useful improvement on the CHO methodology, while retaining its essential features. PMID:19211351

  3. To assess the intimal thickness, flow velocities, and luminal diameter of carotid arteries using high-resolution B-mode ultrasound doppler imaging

    NASA Astrophysics Data System (ADS)

    Vemuru, Madhuri; Jabbar, Afzal; Chandra, Suman

    2004-04-01

    Carotid imaging is a Gold Standard test that provides useful information about the structure and functions of carotid arteries. Spectral imaging helps to evaluate the vessel and hemodynamic changes. High resolution B-mode imaging has emerged as one of the methods of choice for determining the anatomic extent of atherosclerosis and its progression and for assessing cardiovascular risks. The measurements made with Doppler correlate well with pathologic measurements. Recent prospective studies have clearly demonstrated that these measurements of carotid intimal thickness are potent predictors of Myocardial Infarction and Stroke. This method appears very attractive as it is non-invasive, extremely safe, well accepted by the patient and relatively inexpensive. It can be performed serially and has the advantage of visualizing the arterial wall in contrast to angiographic techniques which provide only an outline of the arterial lumen. Recently, there has been an interest in the clinical use of this technique in making difficult clinical decisions like deciding on preventive therapies. 30 subjects aged 21-60 years and 30 subjects aged 61-85 years of both sexes are selected after doing a baseline study to exclude Hypertension, Diabetes, Obesity and Hyperlipidemia. The carotid arteries were examined for intimal thickening, blood flow velocities and luminal diameter. With aging there is a narrowing of the carotid vessels and significant increase in intimal thickening with a consequent increase in the blood flow velocities. Inter-observer, intra-observer and instrument variations are seen and there is no significant change in the values when the distal flow pattern is considered for measurements. Aging produces major cardiovascular changes including decreased elasticity and compliance of great arteries leading to structural and functional alterations in heart and vessels. With aging there is increased intimal thickness and increased pulse wave velocity which is clearly understood by using high resolution B-Mode carotid imaging techniques.

  4. Neuron Image Analyzer: Automated and Accurate Extraction of Neuronal Data from Low Quality Images

    PubMed Central

    Kim, Kwang-Min; Son, Kilho; Palmore, G. Tayhas R.

    2015-01-01

    Image analysis software is an essential tool used in neuroscience and neural engineering to evaluate changes in neuronal structure following extracellular stimuli. Both manual and automated methods in current use are severely inadequate at detecting and quantifying changes in neuronal morphology when the images analyzed have a low signal-to-noise ratio (SNR). This inadequacy derives from the fact that these methods often include data from non-neuronal structures or artifacts by simply tracing pixels with high intensity. In this paper, we describe Neuron Image Analyzer (NIA), a novel algorithm that overcomes these inadequacies by employing Laplacian of Gaussian filter and graphical models (i.e., Hidden Markov Model, Fully Connected Chain Model) to specifically extract relational pixel information corresponding to neuronal structures (i.e., soma, neurite). As such, NIA that is based on vector representation is less likely to detect false signals (i.e., non-neuronal structures) or generate artifact signals (i.e., deformation of original structures) than current image analysis algorithms that are based on raster representation. We demonstrate that NIA enables precise quantification of neuronal processes (e.g., length and orientation of neurites) in low quality images with a significant increase in the accuracy of detecting neuronal changes post-stimulation. PMID:26593337

  5. Neuron Image Analyzer: Automated and Accurate Extraction of Neuronal Data from Low Quality Images.

    PubMed

    Kim, Kwang-Min; Son, Kilho; Palmore, G Tayhas R

    2015-01-01

    Image analysis software is an essential tool used in neuroscience and neural engineering to evaluate changes in neuronal structure following extracellular stimuli. Both manual and automated methods in current use are severely inadequate at detecting and quantifying changes in neuronal morphology when the images analyzed have a low signal-to-noise ratio (SNR). This inadequacy derives from the fact that these methods often include data from non-neuronal structures or artifacts by simply tracing pixels with high intensity. In this paper, we describe Neuron Image Analyzer (NIA), a novel algorithm that overcomes these inadequacies by employing Laplacian of Gaussian filter and graphical models (i.e., Hidden Markov Model, Fully Connected Chain Model) to specifically extract relational pixel information corresponding to neuronal structures (i.e., soma, neurite). As such, NIA that is based on vector representation is less likely to detect false signals (i.e., non-neuronal structures) or generate artifact signals (i.e., deformation of original structures) than current image analysis algorithms that are based on raster representation. We demonstrate that NIA enables precise quantification of neuronal processes (e.g., length and orientation of neurites) in low quality images with a significant increase in the accuracy of detecting neuronal changes post-stimulation. PMID:26593337

  6. Evaluation of Extrahepatic Perfusion of Anticancer Drugs in the Right Gastric Arterial Region on Fused Images Using Combined CT/SPECT: Is Extrahepatic Perfusion Predictive of Gastric Toxicity?

    SciTech Connect

    Ikeda, Osamu Tamura, Yoshitaka; Nakasone, Yutaka; Shiraishi, Shinya; Kawanaka, Kouichi; Tomiguchi, Seiji; Morishita, Shouji; Takamori, Hiroshi; Chikamoto, Akira; Kanemitsu, Keiichirou; Yamashita, Yasuyuki

    2007-06-15

    Background. Hepatic arterial infusion (HAI) chemotherapy is effective for treating primary and metastatic carcinomas of the liver. Since hepatic arteries also supply the stomach and duodenum, HAI may result in unwanted infusion into the upper gastrointestinal tract and consequent gastric toxicity. Using fused images obtained with a combined SPECT/CT system, we assessed extrahepatic perfusion (EHP) and its correlation with gastrointestinal toxicity in patients receiving HAI. Methods. We studied 41 patients with primary or metastatic carcinoma of the liver who received HAI chemotherapy consisting of 5-fluorouracil and cisplatin. All underwent abdominal SPECT using a {sup 99m}Tc-MAA (185 MBq) instrument and an injection rate of 0.1 ml/min, identical to the chemotherapy infusion rate. Delivery was through an implantable port. We analyzed the distribution of the anticancer agent on fused images and the relationship between EHP of the right gastric arterial region and gastric toxicity. All patients underwent esophagogastroduodenoscopy (EGDS). Results. Of the 41 patients, 11 (27%) manifested enhancement of the duodenal and gastric pyloric region on fused images. EGDS at the time of reservoir placement detected gastric ulcers in 10 of these patients. Conclusion. Fusion imaging with combined SPECT/CT reflects the actual distribution of the infused anticancer agents. The detection of EHP on fused images is predictive of the direct gastric toxicity from anticancer agents in patients undergoing HAI.

  7. Image quality comparison of high-energy phase contrast x-ray images with low-energy conventional images: phantom studies

    NASA Astrophysics Data System (ADS)

    Wong, Molly; Wu, Xizeng; Liu, Hong

    2010-02-01

    A significant challenge in the field of mammography that has yet to be overcome involves providing adequate image quality for detection and diagnosis, while minimizing the radiation dose to the patient. An emerging x-ray technology, high energy phase contrast imaging holds the potential to reduce the patient dose without compromising the image quality, which would benefit the early detection of breast cancer. The purpose of this preliminary study was to compare the image quality of high energy phase contrast images to conventional x-ray images at typical mammography energies. The experimental settings were selected to provide similar entrance exposures for the high and low energy images. Several phantoms were utilized in this study to provide a comprehensive image quality comparison, in an effort to investigate the clinical potential of high energy phase contrast imaging. An ACR phantom was utilized for quantitative comparison through an observer study, while a new tissue-equivalent phantom was utilized for a qualitative investigation. Finally, an acrylic-edge phantom was employed to provide an illustration of the edge enhancement in the phase contrast images as compared to the conventional images. The results from the multi-faceted comparison indicate the potential of high energy phase contrast imaging to provide comparable image quality at a similar or decreased patient dose.

  8. Coronary artery disease in women.

    PubMed Central

    Chiamvimonvat, V.; Sternberg, L.

    1998-01-01

    OBJECTIVE: To review and recognize how presentation, investigation, risk factor modification, and treatment of coronary artery disease (CAD) is different for women than for men. QUALITY OF EVIDENCE: Epidemiologic data are from well-recognized, peer-reviewed medical journals. Most data on treatment are from randomized controlled trials. MAIN FINDINGS: Coronary artery disease is the leading cause of mortality in women, with incidence after menopause equal to that of men. Diabetes and postmenopausal status without hormone replacement therapy are the strongest risk factors. Women with CAD are more likely to have atypical symptoms, including nonexertional chest pain; pain in other locations, such as jaw, arms, shoulder, back, and epigastrium; and angina-equivalents, such as dyspnea, palpitations, and presyncope. Because women have atypical symptoms, physicians should maintain a high level of suspicion. Although newer nonivasive stress imaging modalities provide greater diagnostic accuracy than traditional exercise stress testing, the tests are still less accurate for women. A safe and cost-effective approach to investigation can be guided by clinical likelihood for CAD based on patients' age, chest pain quality, and risk factors. Treatment and preventive strategies are generally similar for women and men. CONCLUSION: Coronary artery disease is a serious cause of morbidity and mortality in women and will continue to gain importance as women's life expectancy increases. Important differences in presentation, risk factors, investigation, and treatment of women exist and should be recognized. PMID:9870124

  9. Development of Software to Model AXAF-I Image Quality

    NASA Technical Reports Server (NTRS)

    Ahmad, Anees; Hawkins, Lamar

    1996-01-01

    This draft final report describes the work performed under the delivery order number 145 from May 1995 through August 1996. The scope of work included a number of software development tasks for the performance modeling of AXAF-I. A number of new capabilities and functions have been added to the GT software, which is the command mode version of the GRAZTRACE software, originally developed by MSFC. A structural data interface has been developed for the EAL (old SPAR) finite element analysis FEA program, which is being used by MSFC Structural Analysis group for the analysis of AXAF-I. This interface utility can read the structural deformation file from the EAL and other finite element analysis programs such as NASTRAN and COSMOS/M, and convert the data to a suitable format that can be used for the deformation ray-tracing to predict the image quality for a distorted mirror. There is a provision in this utility to expand the data from finite element models assuming 180 degrees symmetry. This utility has been used to predict image characteristics for the AXAF-I HRMA, when subjected to gravity effects in the horizontal x-ray ground test configuration. The development of the metrology data processing interface software has also been completed. It can read the HDOS FITS format surface map files, manipulate and filter the metrology data, and produce a deformation file, which can be used by GT for ray tracing for the mirror surface figure errors. This utility has been used to determine the optimum alignment (axial spacing and clocking) for the four pairs of AXAF-I mirrors. Based on this optimized alignment, the geometric images and effective focal lengths for the as built mirrors were predicted to cross check the results obtained by Kodak.

  10. Improving a DWT-based compression algorithm for high image-quality requirement of satellite images

    NASA Astrophysics Data System (ADS)

    Thiebaut, Carole; Latry, Christophe; Camarero, Roberto; Cazanave, Grégory

    2011-10-01

    Past and current optical Earth observation systems designed by CNES are using a fixed-rate data compression processing performed at a high-rate in a pushbroom mode (also called scan-based mode). This process generates fixed-length data to the mass memory and data downlink is performed at a fixed rate too. Because of on-board memory limitations and high data rate processing needs, the rate allocation procedure is performed over a small image area called a "segment". For both PLEIADES compression algorithm and CCSDS Image Data Compression recommendation, this rate allocation is realised by truncating to the desired rate a hierarchical bitstream of coded and quantized wavelet coefficients for each segment. Because the quantisation induced by truncation of the bit planes description is the same for the whole segment, some parts of the segment have a poor image quality. These artefacts generally occur in low energy areas within a segment of higher level of energy. In order to locally correct these areas, CNES has studied "exceptional processing" targeted for DWT-based compression algorithms. According to a criteria computed for each part of the segment (called block), the wavelet coefficients can be amplified before bit-plane encoding. As usual Region of Interest handling, these multiplied coefficients will be processed earlier by the encoder than in the nominal case (without exceptional processing). The image quality improvement brought by the exceptional processing has been confirmed by visual image analysis and fidelity criteria. The complexity of the proposed improvement for on-board application has also been analysed.

  11. Image Quality and Radiation Dose of CT Coronary Angiography with Automatic Tube Current Modulation and Strong Adaptive Iterative Dose Reduction Three-Dimensional (AIDR3D)

    PubMed Central

    Shen, Hesong; Dai, Guochao; Luo, Mingyue; Duan, Chaijie; Cai, Wenli; Liang, Dan; Wang, Xinhua; Zhu, Dongyun; Li, Wenru; Qiu, Jianping

    2015-01-01

    Purpose To investigate image quality and radiation dose of CT coronary angiography (CTCA) scanned using automatic tube current modulation (ATCM) and reconstructed by strong adaptive iterative dose reduction three-dimensional (AIDR3D). Methods Eighty-four consecutive CTCA patients were collected for the study. All patients were scanned using ATCM and reconstructed with strong AIDR3D, standard AIDR3D and filtered back-projection (FBP) respectively. Two radiologists who were blinded to the patients' clinical data and reconstruction methods evaluated image quality. Quantitative image quality evaluation included image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). To evaluate image quality qualitatively, coronary artery is classified into 15 segments based on the modified guidelines of the American Heart Association. Qualitative image quality was evaluated using a 4-point scale. Radiation dose was calculated based on dose-length product. Results Compared with standard AIDR3D, strong AIDR3D had lower image noise, higher SNR and CNR, their differences were all statistically significant (P<0.05); compared with FBP, strong AIDR3D decreased image noise by 46.1%, increased SNR by 84.7%, and improved CNR by 82.2%, their differences were all statistically significant (P<0.05 or 0.001). Segments with diagnostic image quality for strong AIDR3D were 336 (100.0%), 486 (96.4%), and 394 (93.8%) in proximal, middle, and distal part respectively; whereas those for standard AIDR3D were 332 (98.8%), 472 (93.7%), 378 (90.0%), respectively; those for FBP were 217 (64.6%), 173 (34.3%), 114 (27.1%), respectively; total segments with diagnostic image quality in strong AIDR3D (1216, 96.5%) were higher than those of standard AIDR3D (1182, 93.8%) and FBP (504, 40.0%); the differences between strong AIDR3D and standard AIDR3D, strong AIDR3D and FBP were all statistically significant (P<0.05 or 0.001). The mean effective radiation dose was (2.55±1.21) mSv. Conclusion Compared with standard AIDR3D and FBP, CTCA with ATCM and strong AIDR3D could significantly improve both quantitative and qualitative image quality. PMID:26599111

  12. Comparative analysis of arterial spin labeling and dynamic susceptibility contrast perfusion imaging for quantitative perfusion measurements of brain tumors.

    PubMed

    Jiang, Jingjing; Zhao, Lingyun; Zhang, Yan; Zhang, Shun; Yao, Yihao; Qin, Yuanyuan; Wang, Cong-Yi; Zhu, Wenzhen

    2014-01-01

    We comparatively analyzed the difference between three-dimensional arterial spin labeling (3D-ASL) and the conventional dynamic susceptibility contrast (DSC) perfusion imaging in the setting of assessing brain tumor perfusion in 28 patients with proved brain tumors. All patients were scheduled with standard MRI, 3D-ASL and DSC scannings on a GE DISCOVERY MR 750 system. Maximal relative tumor perfusion was obtained based on the region of interest (ROI) method. A close correlation between 3D-ASL and DSC perfusion imaging was noted as manifested by the absence of significant differences between ASL nTBF and DSC nTBF when normalized to M (mirror region) and GM (contralateral gray matter). However, ASL nTBF was found to be highly correlated with DSC nTBF and DSC nTBV when normalized to M, GM and WM (contralateral normal white matter). Together, our data support that 3D-ASL possesses the potential to be a noninvasive alternate for DSC-MRI in assessing brain tumor perfusion in the setting of treatment prognosis and metastasis, particularly for those patients with renal failure and patients required for collection of follow up information. PMID:25031698

  13. Quantification of radiographic image quality based on patient anatomical contrast-to-noise ratio: a preliminary study with chest images

    NASA Astrophysics Data System (ADS)

    Lin, Yuan; Wang, Xiaohui; Sehnert, William J.; Foos, David H.; Barski, Lori; Samei, Ehsan

    2010-02-01

    The quality of a digital radiograph for diagnostic imaging depends on many factors, such as the capture system DQE and MTF, the exposure technique factors, the patient anatomy, and the particular image processing method and processing parameters used. Therefore, the overall image quality as perceived by the radiologists depends on many factors. This work explores objective image quality metrics directly from display-ready patient images. A preliminary study was conducted based on a multi-frequency analysis of anatomy contrast and noise magnitude from 250 computed radiography (CR) chest radiographs (150 PA, 50 AP captured with anti-scatter grids, and 50 AP without grids). The contrast and noise values were evaluated in different sub-bands separately according to their frequency properties. Contrast-Noise ratio (CNR) was calculated, the results correlated well with the human observers' overall impression on the images captured with and without grids.

  14. Multi-Detector Coronary CT Imaging for the Identification of Coronary Artery Stenoses in a “Real-World” Population

    PubMed Central

    Makaryus, Amgad N; Henry, Sonia; Loewinger, Lee; Makaryus, John N; Boxt, Lawrence

    2014-01-01

    BACKGROUND Multi-detector computed tomography (CT) has emerged as a modality for the non-invasive assessment of coronary artery disease (CAD). Prior studies have selected patients for evaluation and have excluded many of the “real-world” patients commonly encountered in daily practice. We compared 64-detector-CT (64-CT) to conventional coronary angiography (CA) to investigate the accuracy of 64-CT in determining significant coronary stenoses in a “real-world” clinical population. METHODS A total of 1,818 consecutive patients referred for 64-CT were evaluated. CT angiography was performed using the GE LightSpeed VCT (GE® Healthcare). Forty-one patients in whom 64-CT results prompted CA investigation were further evaluated, and results of the two diagnostic modalities were compared. RESULTS A total of 164 coronary arteries and 410 coronary segments were evaluated in 41 patients (30 men, 11 women, age 39–85 years) who were identified by 64-CT to have significant coronary stenoses and who thereafter underwent CA. The overall per-vessel sensitivity, specificity, positive predictive value, negative predictive value, and accuracy at the 50% stenosis level were 86%, 84%, 65%, 95%, and 85%, respectively, and 77%, 93%, 61%, 97%, and 91%, respectively, in the per-segment analysis at the 50% stenosis level. CONCLUSION 64-CT is an accurate imaging tool that allows a non-invasive assessment of significant CAD with a high diagnostic accuracy in a “real-world” population of patients. The sensitivity and specificity that we noted are not as high as those in prior reports, but we evaluated a population of patients that is typically encountered in clinical practice and therefore see more “real-world” results. PMID:25628513

  15. Wavelet-based filtering of OCT-data: application to study cerebral arteries

    NASA Astrophysics Data System (ADS)

    Pavlov, Alexey N.; Semyachkina-Glushkovskaya, Oxana V.; Lychagov, Vladislav V.

    2013-02-01

    Wavelets are widely used to improve the quality of images by digital filtering of noise. In this work, application of wavelet-filtering to OCT-images is considered. The problem of appropriate selection of the wavelet-basis is discussed and analysis of cerebral arteries in newborn rats is performed.

  16. Lumen segmentation and motion estimation in B-mode and contrast-enhanced ultrasound images of the carotid artery in patients with atherosclerotic plaque.

    PubMed

    Carvalho, Diego D B; Akkus, Zeynettin; van den Oord, Stijn C H; Schinkel, Arend F L; van der Steen, Antonius F W; Niessen, Wiro J; Bosch, Johan G; Klein, Stefan

    2015-04-01

    In standard B-mode ultrasound (BMUS), segmentation of the lumen of atherosclerotic carotid arteries and studying the lumen geometry over time are difficult owing to irregular lumen shapes, noise, artifacts, and echolucent plaques. Contrast enhanced ultrasound (CEUS) improves lumen visualization, but lumen segmentation remains challenging owing to varying intensities, CEUS-specific artifacts and lack of tissue visualization. To overcome these challenges, we propose a novel method using simultaneously acquired BMUS&CEUS image sequences. Initially, the method estimates nonrigid motion (NME) from the image sequences, using intensity-based image registration. The motion-compensated image sequence is then averaged to obtain a single "epitome" image with improved signal-to-noise ratio. The lumen is segmented from the epitome image through an intensity joint-histogram classification and a graph-based segmentation. NME was validated by comparing displacements with manual annotations in 11 carotids. The average root mean square error (RMSE) was 112±73 ?m . Segmentation results were validated against manual delineations in the epitome images of two different datasets, respectively containing 11 (RMSE 191±43 ?m) and 10 (RMSE 351±176 ?m ) carotids. From the deformation fields, we derived arterial distensibility with values comparable to the literature. The average errors in all experiments were in the inter-observer variability range. To the best of our knowledge, this is the first study exploiting combined BMUS&CEUS images for atherosclerotic carotid lumen segmentation. PMID:25423650

  17. Assessment of Lipiodol Deposition and Residual Cancer for Hepatocellular Carcinoma After Transcatheter Arterial Chemoembolization via Iodine-Based Material Decomposition Images with Spectral Computed Tomography Imaging: A Preliminary Study

    PubMed Central

    Xu, Yanhong; Xiao, An; Yang, Jia; Zhang, Zaixian; Zhang, Guixiang

    2015-01-01

    Background: It is critical to follow up hepatocellular carcinoma (HCC) after transcatheter arterial chemoembolization (TACE) in clinical practice. Computed tomography (CT) is used to assess lipiodol deposition, whereas it is difficult to assess hypovascular residual cancer masked by lipiodol. In contrast, magnetic resonance imaging (MRI) is superior to CT in showing residual cancer, but cannot display lipiodol deposition. Objectives: The aim of this study was to investigate the value of spectral CT imaging in both lipiodol deposition and residual cancer for HCC patients after TACE. Patients and Methods: Ten HCC patients after treated with TACE underwent Discovery CT750 HD and MRI750 3T examination. Receiver operating characteristic (ROC) curves of iodine-based material decomposition images, monochromatic images and conventional CT images were generated. Results: Consequently, 30 residual lesions were detected in MRI of 10 patients. They were found in iodine-based images and monochromatic images versus 29 in conventional CT images. The area under ROC curves for the lesion-to-normal parenchyma ratio (LNR) on arterial phase (AP) in iodine-based material decomposition images, monochromatic images and conventional CT images were 0.933, 0.833 and 0.817, respectively. Conclusion: The study data highlighted good value of iodine-based material decomposition images of spectral CT in assessment of both lipiodol deposition and residual cancer for follow-up of HCC patients previously treated with TACE. PMID:26715981

  18. Circular-ELM for the reduced-reference assessment of perceived image quality

    E-print Network

    Circular-ELM for the reduced-reference assessment of perceived image quality Sergio Decherchi Drive 1, Singapore 117411, Singapore a r t i c l e i n f o Key words: Extreme learning machine Circular backpropagation Image quality assessment a b s t r a c t Providing a satisfactory visual experience is one

  19. Effectiveness of Doppler Image of the Vertebral Artery as an Anatomical Landmark for Identification of Ultrasound-Guided Target Level in Cervical Spine

    PubMed Central

    Choi, Dong-Hyuk; Lee, Jeong-Ho; Park, Ji-Hoon; Choi, Yong-Soo

    2015-01-01

    Study Design A prospective sonographic study. Purpose To verify the effectiveness of simultaneous application of two landmarks, Doppler image of the vertebral artery and shape of the transverse tubercle of the seventh cervical (C7) vertebra. Overview of Literature Counting upwards from the C7 vertebra which only has a posterior tubercle of the transverse process is a commonly used method for ultrasound-guided cervical nerve root block. However, each transverse process has a different shape. Methods Sonograms of 20 volunteers were examined. At first, we identified the C7 transverse process based on the presence of the vertebral artery without the anterior tubercle. The C5 and C6 transverse processes were identified based on the presence of anterior tubercle without the vertebral artery. Subsequently, we placed needles on the C5, C6, and C7 transverse processes and the location and direction of needles were confirmed by fluoroscopy. Results In the 120 segments, 93.3% of needles were placed correctly as desired; 97.5% of needles were placed on the 5C transverse process; 97.5% of needles were placed on the C6 transverse process; and 85.0% of needles were placed on the C7 transverse process, respectively. Both sides showed the same accuracy of 93.3%. Conclusions Simultaneous application of Doppler image of the vertebral artery and shape of the C7 transverse tubercle showed 93.3% accuracy in identifying the target cervical level. Therefore, Doppler image of the vertebral artery can be considered to be a useful landmark for ultrasound-guided cervical nerve root block. PMID:26435784

  20. Angioplasty and stenting for severe vertebral artery orifice stenosis: effects on cerebellar function remodeling verified by blood oxygen level-dependent functional magnetic resonance imaging

    PubMed Central

    Liu, Bo; Li, Zhiwei; Xie, Peng

    2014-01-01

    Vertebral artery orifice stenting may improve blood supply of the posterior circulation of the brain to regions such as the cerebellum and brainstem. However, previous studies have mainly focused on recovery of cerebral blood flow and perfusion in the posterior circulation after interventional therapy. This study examined the effects of functional recovery of local brain tissue on cerebellar function remodeling using blood oxygen level-dependent functional magnetic resonance imaging before and after interventional therapy. A total of 40 Chinese patients with severe unilateral vertebral artery orifice stenosis were enrolled in this study. Patients were equally and randomly assigned to intervention and control groups. The control group received drug treatment only. The intervention group received vertebral artery orifice angioplasty and stenting + identical drug treatment to the control group. At 13 days after treatment, the Dizziness Handicap Inventory score was compared between the intervention and control groups. Cerebellar function remodeling was observed between the two groups using blood oxygen level-dependent functional magnetic resonance imaging. The improvement in dizziness handicap and cerebellar function was more obvious in the intervention group than in the control group. Interventional therapy for severe vertebral artery orifice stenosis may effectively promote cerebellar function remodeling and exert neuroprotective effects. PMID:25657727

  1. Multi-level tree analysis of pulmonary artery/vein trees in non-contrast CT images

    NASA Astrophysics Data System (ADS)

    Gao, Zhiyun; Grout, Randall W.; Hoffman, Eric A.; Saha, Punam K.

    2012-02-01

    Diseases like pulmonary embolism and pulmonary hypertension are associated with vascular dystrophy. Identifying such pulmonary artery/vein (A/V) tree dystrophy in terms of quantitative measures via CT imaging significantly facilitates early detection of disease or a treatment monitoring process. A tree structure, consisting of nodes and connected arcs, linked to the volumetric representation allows multi-level geometric and volumetric analysis of A/V trees. Here, a new theory and method is presented to generate multi-level A/V tree representation of volumetric data and to compute quantitative measures of A/V tree geometry and topology at various tree hierarchies. The new method is primarily designed on arc skeleton computation followed by a tree construction based topologic and geometric analysis of the skeleton. The method starts with a volumetric A/V representation as input and generates its topologic and multi-level volumetric tree representations long with different multi-level morphometric measures. A new recursive merging and pruning algorithms are introduced to detect bad junctions and noisy branches often associated with digital geometric and topologic analysis. Also, a new notion of shortest axial path is introduced to improve the skeletal arc joining two junctions. The accuracy of the multi-level tree analysis algorithm has been evaluated using computer generated phantoms and pulmonary CT images of a pig vessel cast phantom while the reproducibility of method is evaluated using multi-user A/V separation of in vivo contrast-enhanced CT images of a pig lung at different respiratory volumes.

  2. Morphometric analysis of small arteries in the human retina using adaptive optics imaging: relationship with blood pressure and focal vascular changes

    PubMed Central

    Koch, Edouard; Rosenbaum, David; Brolly, Aurélie; Sahel, José-Alain; Chaumet-Riffaud, Philippe; Girerd, Xavier; Rossant, Florence; Paques, Michel

    2014-01-01

    Objectives: The wall-to-lumen ratio (WLR) of retinal arteries is a recognized surrogate of end-organ damage due to aging and/or arterial hypertension. However, parietal morphometry remains difficult to assess in vivo. Recently, it was shown that adaptive optics retinal imaging can resolve parietal structures of retinal arterioles in humans in vivo. Here, using adaptive optics retinal imaging, we investigated the variations of parietal thickness of small retinal arteries with blood pressure and focal vascular damage. Methods: Adaptive optics imaging of the superotemporal retinal artery was done in 49 treatment-naive individuals [mean age (±SD) 44.9 years (±14); mean systolic pressure 132?mmHg (±22)]. Semi-automated segmentation allowed extracting parietal thickness and lumen diameter. In a distinct cohort, adaptive optics images of arteriovenous nicking (AVN; n?=?12) and focal arteriolar narrowing (FAN; n?=?10) were also analyzed qualitatively and quantitatively. Results: In the cohort of treatment-naive individuals, by multiple regression taking into account age, body mass index, mean, systolic, diastolic and pulse blood pressure, the WLR was found positively correlated to mean blood pressure and age which in combination accounted for 43% of the variability of WLR. In the cohort of patients with focal vascular damage, neither FANs or AVNs showed evidence of parietal growth; instead, at sites of FANs, decreased outer diameter suggestive of vasoconstriction was consistently found, while at sites of AVNs venous narrowing could be seen in the absence of arteriovenous contact. Conclusion: High resolution imaging of retinal vessels by adaptive optics allows quantitative microvascular phenotyping, which may contribute to a better understanding and management of hypertensive retinopathy. PMID:24406779

  3. Comparison of image quality, myocardial perfusion, and LV function between standard imaging and single-injection ultra-low-dose imaging using a high-efficiency SPECT camera: the MILLISIEVERT study

    PubMed Central

    Einstein, Andrew J.; Blankstein, Ron; Andrews, Howard; Fish, Mathews; Padgett, Richard; Hayes, Sean W.; Friedman, John D.; Qureshi, Mehreen; Rakotoarivelo, Harivony; Slomka, Piotr; Nakazato, Ryo; Bokhari, Sabahat; Di Carli, Marcello; Berman, Daniel S.

    2015-01-01

    SPECT myocardial perfusion imaging (MPI) plays a central role in coronary artery disease diagnosis; but concerns exist regarding its radiation burden. Compared to standard Anger-SPECT (A-SPECT) cameras, new high-efficiency (HE) cameras with specialized collimators and solid-state cadmium-zinc-telluride detectors offer potential to maintain image quality (IQ), while reducing administered activity and thus radiation dose to patients. No previous study has compared IQ, interpretation, total perfusion deficit (TPD), or ejection fraction (EF) in patients receiving both ultra-low-dose (ULD) imaging on a HE-SPECT camera and standard low-dose (SLD) A-SPECT imaging. Methods We compared ULD-HE-SPECT to SLD-A-SPECT imaging by dividing the rest dose in 101 patients at 3 sites scheduled to undergo clinical A-SPECT MPI using a same day rest/stress Tc-99m protocol. Patients received HE-SPECT imaging following an initial ~130 MBq (3.5mCi) dose, and SLD-A-SPECT imaging following the remainder of the planned dose. Images were scored visually by 2 blinded readers for IQ and summed rest score (SRS). TPD and EF were assessed quantitatively. Results Mean activity was 134 MBq (3.62 mCi) for ULD-HE-SPECT (effective dose 1.15 mSv) and 278 MBq (7.50 mCi, 2.39 mSv) for SLD-A-SPECT. Overall IQ was superior for ULD-HE-SPECT (p<0.0001), with twice as many studies graded excellent quality. Extracardiac activity and overall perfusion assessment were similar. Between-method correlations were high for SRS (r=0.87), TPD (r=0.91), and EF (r=0.88). Conclusion ULD-HE-SPECT rest imaging correlates highly with SLD-A-SPECT. It has improved image quality, comparable extracardiac activity, and achieves radiation dose reduction to 1 mSv for a single injection. PMID:24982439

  4. Subjective image quality comparison between two digital dental radiographic systems and conventional dental film

    PubMed Central

    Ajmal, Muhammed; Elshinawy, Mohamed I.

    2014-01-01

    Objectives Digital radiography has become an integral part of dentistry. Digital radiography does not require film or dark rooms, reduces X-ray doses, and instantly generates images. The aim of our study was to compare the subjective image quality of two digital dental radiographic systems with conventional dental film. Materials & methods A direct digital (DD) ‘Digital’ system by Sirona, a semi-direct (SD) digital system by Vista-scan, and Kodak ‘E’ speed dental X-ray films were selected for the study. Endodontically-treated extracted teeth (n = 25) were used in the study. Details of enamel, dentin, dentino-enamel junction, root canal filling (gutta percha), and simulated apical pathology were investigated with the three radiographic systems. The data were subjected to statistical analyzes to reveal differences in subjective image quality. Results Conventional dental X-ray film was superior to the digital systems. For digital systems, DD imaging was superior to SD imaging. Conclusion Conventional film yielded superior image quality that was statistically significant in almost all aspects of comparison. Conventional film was followed in image quality by DD, and SD provided the lowest quality images. Conventional film is still considered the gold standard to diagnose diseases affecting the jawbone. Recommendations Improved software and hardware for digital imaging systems are now available and these improvements may now yield images that are comparable in quality to conventional film. However, we recommend that studies still use more observers and other statistical methods to produce ideal results. PMID:25382946

  5. Depression Mediates the Effect of Sexual Function on Quality of Life among Men but Not Women with Coronary Artery Disease

    PubMed Central

    Assari, Shervin

    2014-01-01

    Background: Poor sexual function is associated with impaired Health-Related Quality of Life (HRQoL), and patients with Coronary Artery Disease (CAD) are not exceptions. It is not known, however, if symptoms of depression mediate the effect of sexual function on HRQoL among men and women with CAD. Objectives: This study aimed to determine the mediating effect of depressive symptoms on the association between sexual function and HRQoL among men and women with CAD. Patients and Methods: This cross-sectional study was conducted on 401 men and 156 women with CAD. Sexual function, measured by the Relation and Sexuality Scale (RSS), was the independent variable. In addition, physical and mental HRQoL measured using physical and mental health summary scores of Short Form 36 (SF-36) were dependent variables. Besides, the severity of depressive symptoms measured by the Hospital Anxiety and Depression Scale (HADS) was conceptualized as the mediator. Age, income, education, and medical comorbidities (Ifudu index) were control variables, and gender was the moderator. Multi-group path analysis was conducted using AMOS20.0 for data analysis. Results: When the effects of age, education, income, and comorbidities were controlled, sexual function was correlated with poor mental HRQoL in both genders. However, the association between sexual function and poor physical HRQoL could be found only among men but not women. Evidence also supported partial mediation of depressive symptoms on the effect of sexual function on mental HRQoL of both men and women. Nonetheless, the results suggested partial mediation of depressive symptoms on the effect of sexual function on physical HRQoL only among men but not women. Conclusions: Symptoms of depression may not have a similar role in explaining the effect of sexual function on physical HRQoL of men and women with CAD. Our findings suggest that only among men, depressive symptoms might be the mechanism by which sexual function affects the CAD patients’ physical HRQoL. PMID:25614862

  6. Digital mammography--DQE versus optimized image quality in clinical environment: an on site study

    NASA Astrophysics Data System (ADS)

    Oberhofer, Nadia; Fracchetti, Alessandro; Springeth, Margareth; Moroder, Ehrenfried

    2010-04-01

    The intrinsic quality of the detection system of 7 different digital mammography units (5 direct radiography DR; 2 computed radiography CR), expressed by DQE, has been compared with their image quality/dose performances in clinical use. DQE measurements followed IEC 62220-1-2 using a tungsten test object for MTF determination. For image quality assessment two different methods have been applied: 1) measurement of contrast to noise ratio (CNR) according to the European guidelines and 2) contrast-detail (CD) evaluation. The latter was carried out with the phantom CDMAM ver. 3.4 and the commercial software CDMAM Analyser ver. 1.1 (both Artinis) for automated image analysis. The overall image quality index IQFinv proposed by the software has been validated. Correspondence between the two methods has been shown figuring out a linear correlation between CNR and IQFinv. All systems were optimized with respect to image quality and average glandular dose (AGD) within the constraints of automatic exposure control (AEC). For each equipment, a good image quality level was defined by means of CD analysis, and the corresponding CNR value considered as target value. The goal was to achieve for different PMMA-phantom thicknesses constant image quality, that means the CNR target value, at minimum dose. All DR systems exhibited higher DQE and significantly better image quality compared to CR systems. Generally switching, where available, to a target/filter combination with an x-ray spectrum of higher mean energy permitted dose savings at equal image quality. However, several systems did not allow to modify the AEC in order to apply optimal radiographic technique in clinical use. The best ratio image quality/dose was achieved by a unit with a-Se detector and W anode only recently available on the market.

  7. Exposure reduction and image quality in orthodontic radiology: a review of the literature

    SciTech Connect

    Taylor, T.S.; Ackerman, R.J. Jr.; Hardman, P.K.

    1988-01-01

    This article summarizes the use of rare earth screen technology to achieve high-quality panoramic and cephalometric radiographs with sizable reductions in patient radiation dosage. Collimation, shielding, quality control, and darkroom procedures are reviewed to further reduce patient risk and improve image quality. 34 references.

  8. Computer measurement of arterial disease

    NASA Technical Reports Server (NTRS)

    Armstrong, J.; Selzer, R. H.; Barndt, R.; Blankenhorn, D. H.; Brooks, S.

    1980-01-01

    Image processing technique quantifies human atherosclerosis by computer analysis of arterial angiograms. X-ray film images are scanned and digitized, arterial shadow is tracked, and several quantitative measures of lumen irregularity are computed. In other tests, excellent agreement was found between computer evaluation of femoral angiograms on living subjects and evaluation by teams of trained angiographers.

  9. Lesion insertion in projection domain for computed tomography image quality assessment

    NASA Astrophysics Data System (ADS)

    Chen, Baiyu; Ma, Chi; Yu, Zhicong; Leng, Shuai; Yu, Lifeng; McCollough, Cynthia

    2015-03-01

    To perform task-based image quality assessment in CT, it is desirable to have a large number of realistic patient images with known diagnostic truth. One effective way to achieve this objective is to create hybrid images that combine patient images with simulated lesions. Because conventional hybrid images generated in the image-domain fails to reflect the impact of scan and reconstruction parameters on lesion appearance, this study explored a projection-domain approach. Liver lesion models were forward projected according to the geometry of a commercial CT scanner to acquire lesion projections. The lesion projections were then inserted into patient projections (decoded from commercial CT raw data with the assistance of the vendor) and reconstructed to acquire hybrid images. To validate the accuracy of the forward projection geometry, simulated images reconstructed from the forward projections of a digital ACR phantom were compared to physically acquired ACR phantom images. To validate the hybrid images, lesion models were inserted into patient images and visually assessed. Results showed that the simulated phantom images and the physically acquired phantom images had great similarity in terms of HU accuracy and high-contrast resolution. The lesions in the hybrid image had a realistic appearance and merged naturally into the liver background. In addition, the inserted lesion demonstrated reconstruction-parameter-dependent appearance. Compared to conventional image-domain approach, our method enables more realistic hybrid images for image quality assessment.

  10. Lesion Insertion in Projection Domain for Computed Tomography Image Quality Assessment

    PubMed Central

    Chen, Baiyu; Yu, Zhicong; Leng, Shuai; Yu, Lifeng

    2015-01-01

    To perform task-based image quality assessment in CT, it is desirable to have a large number of realistic patient images with known diagnostic truth. One effective way to achieve this objective is to create hybrid images that combine patient images with simulated lesions. Because conventional hybrid images generated in the image-domain fails to reflect the impact of scan and reconstruction parameters on lesion appearance, this study explored a projection-domain approach. Liver lesion models were forward projected according to the geometry of a commercial CT scanner to acquire lesion projections. The lesion projections were then inserted into patient projections (decoded from commercial CT raw data with the assistance of the vendor) and reconstructed to acquire hybrid images. To validate the accuracy of the forward projection geometry, simulated images reconstructed from the forward projections of a digital ACR phantom were compared to physically acquired ACR phantom images. To validate the hybrid images, lesion models were inserted into patient images and visually assessed. Results showed that the simulated phantom images and the physically acquired phantom images had great similarity in terms of HU accuracy and high-contrast resolution. The lesions in the hybrid image had a realistic appearance and merged naturally into the liver background. In addition, the inserted lesion demonstrated reconstruction-parameter-dependent appearance. Compared to conventional image-domain approach, our method enables more realistic hybrid images for image quality assessment. PMID:26146445

  11. Recent Developments in Hyperspectral Imaging for Assessment of Food Quality and Safety

    PubMed Central

    Huang, Hui; Liu, Li; Ngadi, Michael O.

    2014-01-01

    Hyperspectral imaging which combines imaging and spectroscopic technology is rapidly gaining ground as a non-destructive, real-time detection tool for food quality and safety assessment. Hyperspectral imaging could be used to simultaneously obtain large amounts of spatial and spectral information on the objects being studied. This paper provides a comprehensive review on the recent development of hyperspectral imaging applications in food and food products. The potential and future work of hyperspectral imaging for food quality and safety control is also discussed. PMID:24759119

  12. Real-time image quality assessment with mixed Lagrange time delay estimation autoregressive (MLTDEAR) model.

    PubMed

    Sim, K S; Tso, C P; Tan, Y Y; Lim, W K

    2007-06-01

    A proposal to assess the quality of scanning electron microscope images using mixed Lagrange time delay estimation technique is presented. With optimal scanning electron microscope scan rate information, online images can be quantified and improved. The online quality assessment technique is embedded onto a scanning electron microscope frame grabber card for real-time image processing. Different images are captured using scanning electron microscope and a database is built to optimally choose filter parameters. An optimum choice of filter parameters is obtained. With the optimum choice of scan rate, noise can be removed from real-time scanning electron microscope images without causing any sample contamination or increasing scanning time. PMID:17535262

  13. Recent developments in hyperspectral imaging for assessment of food quality and safety.

    PubMed

    Huang, Hui; Liu, Li; Ngadi, Michael O

    2014-01-01

    Hyperspectral imaging which combines imaging and spectroscopic technology is rapidly gaining ground as a non-destructive, real-time detection tool for food quality and safety assessment. Hyperspectral imaging could be used to simultaneously obtain large amounts of spatial and spectral information on the objects being studied. This paper provides a comprehensive review on the recent development of hyperspectral imaging applications in food and food products. The potential and future work of hyperspectral imaging for food quality and safety control is also discussed. PMID:24759119

  14. Locoregional Drug Delivery Using Image-guided Intra-arterial Drug Eluting Bead Therapy

    PubMed Central

    Lewis, Andrew L.; Dreher, Matthew R.

    2012-01-01

    Lipiodol-based transarterial chemoembolization (TACE) has been performed for over 3 decades for the treatment of solid tumors and describes the infusion of chemotherapeutic agents followed by embolization with particles. TACE is an effective treatment for inoperable hepatic tumors, especially hypervascular tumors such as hepatocellular carcinoma. Recently, drug eluting beads (DEBs), in which a uniform embolic material is loaded with a drug and delivered in a single image-guided step, have been developed to reduce the variability in a TACE procedure. DEB-TACE results in localization of drug to targeted tumors while minimizing systemic exposure to chemotherapeutics. Once localized in the tissue, drug is eluted from the DEB in a controlled manner and penetrates hundreds of microns of tissue from the DEB surface. Necrosis is evident surrounding a DEB in tissue days to months after therapy; however, the contribution of drug and ischemia is currently unknown. Future advances in DEB technology may include image-ability, DEB size tailored to tumor anatomy and drug combinations. PMID:22285550

  15. Non-reference quality assessment of infrared images reconstructed by compressive sensing

    NASA Astrophysics Data System (ADS)

    Ospina-Borras, J. E.; Benitez-Restrepo, H. D.

    2015-01-01

    Infrared (IR) images are representations of the world and have natural features like images in the visible spectrum. As such, natural features from infrared images support image quality assessment (IQA).1 In this work, we compare the quality of a set of indoor and outdoor IR images reconstructed from measurement functions formed by linear combination of their pixels. The reconstruction methods are: linear discrete cosine transform (DCT) acquisition, DCT augmented with total variation minimization, and compressive sensing scheme. Peak Signal to Noise Ratio (PSNR), three full-reference (FR), and four no-reference (NR) IQA measures compute the qualities of each reconstruction: multi-scale structural similarity (MSSIM), visual information fidelity (VIF), information fidelity criterion (IFC), sharpness identification based on local phase coherence (LPC-SI), blind/referenceless image spatial quality evaluator (BRISQUE), naturalness image quality evaluator (NIQE) and gradient singular value decomposition (GSVD), respectively. Each measure is compared to human scores that were obtained by differential mean opinion score (DMOS) test. We observe that GSVD has the highest correlation coefficients of all NR measures, but all FR have better performance. We use MSSIM to compare the reconstruction methods and we find that CS scheme produces a good-quality IR image, using only 30000 random sub-samples and 1000 DCT coefficients (2%). In contrast, linear DCT provides higher correlation coefficients than CS scheme by using all the pixels of the image and 31000 DCT (47%) coefficients.

  16. A new imaging technique for retinal vessel oximetry: principles and first clinical results in patients with retinal arterial occlusion and diabetic retinopathy

    NASA Astrophysics Data System (ADS)

    Hammer, M.; Riemer, T.; Vilser, W.; Gehlert, S.; Schweitzer, D.

    2009-02-01

    The oxygen saturation of blood inside retinal vessels is an essential measure for the estimation of oxygen supply to the tissue as well as its oxygen consumption. In the current approach, the blood oxygenation is measured by a dual-wavelength technique. Using a fundus camera, equipped with a special dual wavelength transmission filter and a color CCD camera, two monochromatic fundus images at 548 nm and 610 nm were recorded simultaneously. The optical densities of retinal vessels for both wavelengths and their ratio, which is known to be proportional to the oxygen saturation, were calculated. From a health control population, mean arterial and venous oxygen saturations were measured of 98+/-10.1% and 65+/-11.7% with reproducibility of 2.52% and 3.25% respectively. In 10 patients with arterial occlusion, a reduction of the arterial oxygen saturation to 78 +/-17% (mean +/- standard deviation, branch arterial occlusion) and 91+/-11% (central arterial occlusion) respectively was found in the occluded vessel. After 5 days on pentoxifilin therapy, the arterial saturation increased to an average of 93+/-12% or 103 +/-6% respectively. In 70 eyes of 42 patients suffering from diabetic retinopathy, an increase of the venous oxygen saturation with the severity of the retinopathy was found (mild nonproliferative retinopathy: 68.4+/-8.2%, moderate non-proliferative retinopathy: 70.5+/-6.8%, severe non-proliferative retinopathy: 72.4+/-7.6%, proliferative retinopathy 75.7+/-8.3%) due to vessel shunting and diabetic changes of the permeability of vessel walls. These first clinical results demonstrate the ability of an accurate measurement of retinal vessel oxygenation with a very simple setup just requiring a special filter in the illumination path of a fundus camera and dedicated software.

  17. Visible to SWIR hyperspectral imaging for produce safety and quality evaluation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hyperspectral imaging techniques, combining the advantages of spectroscopy and imaging, have found wider use in food quality and safety evaluation applications during the past decade. In light of the prevalent use of hyperspectral imaging techniques in the visible to near-infrared (VNIR: 400 -1000 n...

  18. OBJECTIVE QUALITY ASSESSMENT FOR IMAGE SUPER-RESOLUTION: A NATURAL SCENE STATISTICS APPROACH

    E-print Network

    Wang, Zhou

    from such statistics characterizes image unnatu- ralness. In the literature of IQA, such unnaturalnessOBJECTIVE QUALITY ASSESSMENT FOR IMAGE SUPER-RESOLUTION: A NATURAL SCENE STATISTICS APPROACH the available LR image as a reference. Our algorithm follows the philosophy behind the natural scene statistics

  19. The quest for "diagnostically lossless" medical image compression: A comparative study of objective quality

    E-print Network

    Wang, Zhou

    The quest for "diagnostically lossless" medical image compression: A comparative study of objective quality metrics for compressed medical images Ilona Kowalik-Urbaniaka, Dominique Bruneta, Jiheng Wangb,NSK) as well as a leading international developer of medical imaging software (AGFA), is primarily concerned

  20. How do we watch images? A case of change detection and quality estimation

    NASA Astrophysics Data System (ADS)

    Radun, Jenni; Leisti, Tuomas; Virtanen, Toni; Nyman, Göte

    2012-01-01

    The most common tasks in subjective image estimation are change detection (a detection task) and image quality estimation (a preference task). We examined how the task influences the gaze behavior when comparing detection and preference tasks. The eye movements of 16 naïve observers were recorded with 8 observers in both tasks. The setting was a flicker paradigm, where the observers see a non-manipulated image, a manipulated version of the image and again the non-manipulated image and estimate the difference they perceived in them. The material was photographic material with different image distortions and contents. To examine the spatial distribution of fixations, we defined the regions of interest using a memory task and calculated information entropy to estimate how concentrated the fixations were on the image plane. The quality task was faster and needed fewer fixations and the first eight fixations were more concentrated on certain image areas than the change detection task. The bottom-up influences of the image also caused more variation to the gaze behavior in the quality estimation task than in the change detection task The results show that the quality estimation is faster and the regions of interest are emphasized more on certain images compared with the change detection task that is a scan task where the whole image is always thoroughly examined. In conclusion, in subjective image estimation studies it is important to think about the task.

  1. Assessment of hepatocellular carcinoma vascularity before and after transcatheter arterial chemoembolization by using first pass perfusion weighted MR imaging

    PubMed Central

    Zhao, Jun-Gong; Feng, Gan-Sheng; Kong, Xiang-Quan; Li, Xin; Li, Ming-Hua; Cheng, Ying-Sheng

    2004-01-01

    AIM: To assess the vascularity of hepatocellular carcinoma (HCC) before and after transcatheter arterial chemoembolization (TACE) with the quantitative parameters obtained by first pass perfusion weighted MR imaging (FP-MRI). METHODS: Seventeen consecutive patients with one to three lesions in liver underwent FP-MRI before treatment. FP-MRI was also performed one, three, six, nine months, and one year after TACE. The baseline signal intensity (S0) of pre-TACE and one month after TACE was analyzed, the vascularity of HCC assessed by steepest slope of the signal intensity versus time curves (SS) was blindly correlated with their DSA feature and clinical outcome. RESULT: No significant difference was found on baseline signal intensity (S0) between pre-TACE and one month after TACE (F = 0.309, P = 0.583), The SS (mean, 32% per second) of lesion one month after TACE was lower than that of pre-TACE (mean, 69% per second), but with no statistical significance (F = 3.067, P = 0.092). When local recurrence occurred, the time intensity curves became steeper. The vascularity of HCC before and after TACE graded by SS closely correlated with that by DSA (K = 0.453, P < 0.05). CONCLUSION: FP-MRI is a useful criterion for selecting effective interventional treatment for patients with HCC in their initial treatment and during follow up. PMID:15069716

  2. Canine model of ischemic stroke with permanent middle cerebral artery occlusion: clinical features, magnetic resonance imaging, histopathology, and immunohistochemistry

    PubMed Central

    Jeon, Joon-Hyeok; Jung, Hae-Won; Jang, Hyo-Mi; Moon, Jong-Hyun; Park, Ki-Tae; Lee, Hee-Chun; Lim, Ha-Young; Sur, Jung-Hyang; Kang, Byeong-Teck; Ha, Jeongim

    2015-01-01

    The purpose of this study was to identify time-related changes in clinical, MRI, histopathologic, and immunohistochemical findings associated with ischemic stroke in dogs. Additionally, the association of cerebrospinal fluid (CSF) and tissue levels of interleukin (IL)-6 with clinical prognosis was assessed. Ischemic stroke was induced by permanent middle cerebral artery occlusion (MCAO) in nine healthy experimental dogs. The dogs were divided into three groups according to survival time and duration of the experimental period: group A (survived only 1 day), group B (1-week experimental period), and group C (2-week experimental period). Neurologic status was evaluated daily. Magnetic resonance imaging (MRI) was performed according to a predetermined schedule. Concentration of IL-6 in CSF was measured serially after ischemic stroke. Postmortem examination was performed for all experimental dogs. During histopathological examination, variable degrees of cavitation and necrosis due to neuronal cytopathic effects, such as pyknotic nuclei and cytoplasmic shrinkage, were observed on the affected side of the cerebral cortex in all dogs. Immunohistochemistry specific for IL-6 showed increased expression in the ischemic lesions. CSF IL-6 concentrations and ischemic lesion volumes 1 day after ischemic stroke were significantly higher in group A compared to groups B and C. PMID:25269716

  3. Quality evaluation of adaptive optical image based on DCT and Rényi entropy

    NASA Astrophysics Data System (ADS)

    Xu, Yuannan; Li, Junwei; Wang, Jing; Deng, Rong; Dong, Yanbing

    2015-04-01

    The adaptive optical telescopes play a more and more important role in the detection system on the ground, and the adaptive optical images are so many that we need find a suitable method of quality evaluation to choose good quality images automatically in order to save human power. It is well known that the adaptive optical images are no-reference images. In this paper, a new logarithmic evaluation method based on the use of the discrete cosine transform(DCT) and Rényi entropy for the adaptive optical images is proposed. Through the DCT using one or two dimension window, the statistical property of Rényi entropy for images is studied. The different directional Rényi entropy maps of an input image containing different information content are obtained. The mean values of different directional Rényi entropy maps are calculated. For image quality evaluation, the different directional Rényi entropy and its standard deviation corresponding to region of interest is selected as an indicator for the anisotropy of the images. The standard deviation of different directional Rényi entropy is obtained as the quality evaluation value for adaptive optical image. Experimental results show the proposed method that the sorting quality matches well with the visual inspection.

  4. Weighted perceptual difference model (case-PDM) for MR image quality evaluation

    NASA Astrophysics Data System (ADS)

    Miao, Jun; Wong, Wilbur C. K.; Wilson, David L.

    2008-03-01

    The perceptual difference model (Case-PDM) is being used to quantify image quality of fast, parallel MR acquisitions and reconstruction algorithms by comparing to slower, full k-space, high quality reference images. To date, most perceptual difference models average a single scalar image quality metric over a large region of interest. In this paper, we create an alternative metric weighted to image processing features. Spatial filters were applied to the reference image to create edge and flat region images, then weighted and aggregated to create "structural" images which in turn spatially weighted the perceptual difference maps. We optimized the scale of the spatial filters and weighting scheme with an exhaustive search so as to improve the linear correlation coefficient between human ratings and weighted Case-PDM, across a large set of MR reconstruction test images of varying quality. Human ratings were obtained from a modified Double Stimulus Continuous Quality Scale experiment. For 5 different images (3 different brain, 1 cardiac, and 1 phantom images), r values [weighted PDM, average PDM] were improved ([0.96, 0.94], [0.93, 0.91], [0.97, 0.95], [0.97, 0.91], [0.96, 0.95]) in all cases. The method is robust across subjects and anatomy; that is, scores maintain a high correlation with human ratings even if the test dataset is different from the training dataset.

  5. SU-E-I-43: Pediatric CT Dose and Image Quality Optimization

    SciTech Connect

    Stevens, G; Singh, R

    2014-06-01

    Purpose: To design an approach to optimize radiation dose and image quality for pediatric CT imaging, and to evaluate expected performance. Methods: A methodology was designed to quantify relative image quality as a function of CT image acquisition parameters. Image contrast and image noise were used to indicate expected conspicuity of objects, and a wide-cone system was used to minimize scan time for motion avoidance. A decision framework was designed to select acquisition parameters as a weighted combination of image quality and dose. Phantom tests were used to acquire images at multiple techniques to demonstrate expected contrast, noise and dose. Anthropomorphic phantoms with contrast inserts were imaged on a 160mm CT system with tube voltage capabilities as low as 70kVp. Previously acquired clinical images were used in conjunction with simulation tools to emulate images at different tube voltages and currents to assess human observer preferences. Results: Examination of image contrast, noise, dose and tube/generator capabilities indicates a clinical task and object-size dependent optimization. Phantom experiments confirm that system modeling can be used to achieve the desired image quality and noise performance. Observer studies indicate that clinical utilization of this optimization requires a modified approach to achieve the desired performance. Conclusion: This work indicates the potential to optimize radiation dose and image quality for pediatric CT imaging. In addition, the methodology can be used in an automated parameter selection feature that can suggest techniques given a limited number of user inputs. G Stevens and R Singh are employees of GE Healthcare.

  6. An image-based technique to assess the perceptual quality of clinical chest radiographs

    SciTech Connect

    Lin Yuan; Luo Hui; Dobbins, James T. III; Page McAdams, H.; Wang, Xiaohui; Sehnert, William J.; Barski, Lori; Foos, David H.; Samei, Ehsan

    2012-11-15

    Purpose: Current clinical image quality assessment techniques mainly analyze image quality for the imaging system in terms of factors such as the capture system modulation transfer function, noise power spectrum, detective quantum efficiency, and the exposure technique. While these elements form the basic underlying components of image quality, when assessing a clinical image, radiologists seldom refer to these factors, but rather examine several specific regions of the displayed patient images, further impacted by a particular image processing method applied, to see whether the image is suitable for diagnosis. In this paper, the authors developed a novel strategy to simulate radiologists' perceptual evaluation process on actual clinical chest images. Methods: Ten regional based perceptual attributes of chest radiographs were determined through an observer study. Those included lung grey level, lung detail, lung noise, rib-lung contrast, rib sharpness, mediastinum detail, mediastinum noise, mediastinum alignment, subdiaphragm-lung contrast, and subdiaphragm area. Each attribute was characterized in terms of a physical quantity measured from the image algorithmically using an automated process. A pilot observer study was performed on 333 digital chest radiographs, which included 179 PA images with 10:1 ratio grids (set 1) and 154 AP images without grids (set 2), to ascertain the correlation between image perceptual attributes and physical quantitative measurements. To determine the acceptable range of each perceptual attribute, a preliminary quality consistency range was defined based on the preferred 80% of images in set 1. Mean value difference ({mu}{sub 1}-{mu}{sub 2}) and variance ratio ({sigma}{sub 1}{sup 2}/{sigma}{sub 2}{sup 2}) were investigated to further quantify the differences between the selected two image sets. Results: The pilot observer study demonstrated that our regional based physical quantity metrics of chest radiographs correlated very well with their corresponding perceptual attributes. The distribution comparisons, mean value difference estimations, and variance ratio estimations of each physical quantity between sets of images from two different techniques matched our expectation that the image quality of set 1 should be better than that of set 2. Conclusions: The measured physical quantities provide a robust reflection of perceptual image quality in clinical images. The methodology can be readily applied for automated evaluation of perceptual image quality in clinical chest radiographs.

  7. A conceptual study of automatic and semi-automatic quality assurance techniques for round image processing

    NASA Technical Reports Server (NTRS)

    1983-01-01

    This report summarizes the results of a study conducted by Engineering and Economics Research (EER), Inc. under NASA Contract Number NAS5-27513. The study involved the development of preliminary concepts for automatic and semiautomatic quality assurance (QA) techniques for ground image processing. A distinction is made between quality assessment and the more comprehensive quality assurance which includes decision making and system feedback control in response to quality assessment.

  8. Local homogeneity combined with DCT statistics to blind noisy image quality assessment

    NASA Astrophysics Data System (ADS)

    Yang, Lingxian; Chen, Li; Chen, Heping

    2015-03-01

    In this paper a novel method for blind noisy image quality assessment is proposed. First, it is believed that human visual system (HVS) is more sensitive to the local smoothness area in a noise image, an adaptively local homogeneous block selection algorithm is proposed to construct a new homogeneous image named as homogeneity blocks (HB) based on computing each pixel characteristic. Second, applying the discrete cosine transform (DCT) for each HB and using high frequency component to evaluate image noise level. Finally, a modified peak signal to noise ratio (MPSNR) image quality assessment approach is proposed based on analysis DCT kurtosis distributions change and noise level above-mentioned. Simulations show that the quality scores that produced from the proposed algorithm are well correlated with the human perception of quality and also have a stability performance.

  9. Human visual system consistent quality assessment for remote sensing image fusion

    NASA Astrophysics Data System (ADS)

    Liu, Jun; Huang, Junyi; Liu, Shuguang; Li, Huali; Zhou, Qiming; Liu, Junchen

    2015-07-01

    Quality assessment for image fusion is essential for remote sensing application. Generally used indices require a high spatial resolution multispectral (MS) image for reference, which is not always readily available. Meanwhile, the fusion quality assessments using these indices may not be consistent with the Human Visual System (HVS). As an attempt to overcome this requirement and inconsistency, this paper proposes an HVS-consistent image fusion quality assessment index at the highest resolution without a reference MS image using Gaussian Scale Space (GSS) technology that could simulate the HVS. The spatial details and spectral information of original and fused images are first separated in GSS, and the qualities are evaluated using the proposed spatial and spectral quality index respectively. The overall quality is determined without a reference MS image by a combination of the proposed two indices. Experimental results on various remote sensing images indicate that the proposed index is more consistent with HVS evaluation compared with other widely used indices that may or may not require reference images.

  10. Posterior Circulation Acute Stroke Prognosis Early Computed Tomography Score Using Hypointense Vessels on Susceptibility Weighted Imaging Independently Predicts Outcome in Patients with Basilar Artery Occlusion

    PubMed Central

    Mundiyanapurath, S.; Möhlenbruch, M.; Ringleb, P. A.; Bösel, J.; Wick, W.; Bendszus, M.; Radbruch, A.

    2015-01-01

    Purpose Appearance of hypointense vessels on susceptibility weighted imaging (SWI) has been reported to correlate with outcome in patients with ischemia of the anterior circulation. This study investigates the correlation between the appearance of hypointense vessels on SWI after recanalization therapy and outcome in patients with basilar artery occlusion. Methods Patients with basilar artery occlusion who were treated with endovascular recanalization or intravenous alteplase and received an MRI including SWI after therapy were retrieved from the hospital database for retrospective analysis. Posterior circulation Acute Stroke Prognosis Early Computed Tomography Score (pcASPECTS) was calculated based on regions displaying hypointense vessels on SWI and compared to lesions on diffusion weighted imaging (DWI). Subsequently, SWI based pcASPECTS was correlated with outcome determined with modified Rankin Scale (mRS), categorized as favorable outcome (mRS 0-2) or unfavorable outcome (3-6). Results Twenty-two MRI of patients with basilar artery occlusion were analyzed. In seven out of eight areas of the pcASPECTS hypointense vessels on SWI were significantly correlated to areas of restricted diffusion on DWI. In univariate analysis median pcASPECTS on SWI was significantly higher in patients with favorable outcome (7.5 vs. 5, p=0.02). In a multivariate analysis pcASPECTS on SWI was an independent predictor of favorable outcome (OR 2.02; CI [1.02;3,99]; p=0.04). Conclusion pcASPECTS based on hypointense vessels on SWI after therapy predicts outcome in patients with basilar artery occlusion and might potentially be used as an additional imaging biomarker in the management of patients with stroke in the posterior circulation. This needs to be confirmed in larger prospective clinical trials. PMID:26176682

  11. Improvement of the image quality of random phase-free holography using an iterative method

    NASA Astrophysics Data System (ADS)

    Shimobaba, Tomoyoshi; Kakue, Takashi; Endo, Yutaka; Hirayama, Ryuji; Hiyama, Daisuke; Hasegawa, Satoki; Nagahama, Yuki; Sano, Marie; Oikawa, Minoru; Sugie, Takashige; Ito, Tomoyoshi

    2015-11-01

    Our proposed method of random phase-free holography using virtual convergence light can obtain large reconstructed images exceeding the size of the hologram, without the assistance of random phase. The reconstructed images have low-speckle noise in the amplitude and phase-only holograms (kinoforms); however, in low-resolution holograms, we obtain a degraded image quality compared to the original image. We propose an iterative random phase-free method with virtual convergence light to address this problem.

  12. Quantitative measurement of holographic image quality using Adobe Photoshop

    NASA Astrophysics Data System (ADS)

    Wesly, E.

    2013-02-01

    Measurement of the characteristics of image holograms in regards to diffraction efficiency and signal to noise ratio are demonstrated, using readily available digital cameras and image editing software. Illustrations and case studies, using currently available holographic recording materials, are presented.

  13. The Analysis of Image Contrast: From Quality Assessment to Automatic Enhancement.

    PubMed

    Gu, Ke; Zhai, Guangtao; Lin, Weisi; Liu, Min

    2016-01-01

    Proper contrast change can improve the perceptual quality of most images, but it has largely been overlooked in the current research of image quality assessment (IQA). To fill this void, we in this paper first report a new large dedicated contrast-changed image database (CCID2014), which includes 655 images and associated subjective ratings recorded from 22 inexperienced observers. We then present a novel reduced-reference image quality metric for contrast change (RIQMC) using phase congruency and statistics information of the image histogram. Validation of the proposed model is conducted on contrast related CCID2014, TID2008, CSIQ and TID2013 databases, and results justify the superiority and efficiency of RIQMC over a majority of classical and state-of-the-art IQA methods. Furthermore, we combine aforesaid subjective and objective assessments to derive the RIQMC based Optimal HIstogram Mapping (ROHIM) for automatic contrast enhancement, which is shown to outperform recently developed enhancement technologies. PMID:25775503

  14. Near-infrared hyperspectral imaging for quality analysis of agricultural and food products

    NASA Astrophysics Data System (ADS)

    Singh, C. B.; Jayas, D. S.; Paliwal, J.; White, N. D. G.

    2010-04-01

    Agricultural and food processing industries are always looking to implement real-time quality monitoring techniques as a part of good manufacturing practices (GMPs) to ensure high-quality and safety of their products. Near-infrared (NIR) hyperspectral imaging is gaining popularity as a powerful non-destructive tool for quality analysis of several agricultural and food products. This technique has the ability to analyse spectral data in a spatially resolved manner (i.e., each pixel in the image has its own spectrum) by applying both conventional image processing and chemometric tools used in spectral analyses. Hyperspectral imaging technique has demonstrated potential in detecting defects and contaminants in meats, fruits, cereals, and processed food products. This paper discusses the methodology of hyperspectral imaging in terms of hardware, software, calibration, data acquisition and compression, and development of prediction and classification algorithms and it presents a thorough review of the current applications of hyperspectral imaging in the analyses of agricultural and food products.

  15. Comparison of retinal image quality with spherical and customized aspheric intraocular lenses

    PubMed Central

    Guo, Huanqing; Goncharov, Alexander V.; Dainty, Chris

    2012-01-01

    We hypothesize that an intraocular lens (IOL) with higher-order aspheric surfaces customized for an individual eye provides improved retinal image quality, despite the misalignments that accompany cataract surgery. To test this hypothesis, ray-tracing eye models were used to investigate 10 designs of mono-focal single lens IOLs with rotationally symmetric spherical, aspheric, and customized surfaces. Retinal image quality of pseudo-phakic eyes using these IOLs together with individual variations in ocular and IOL parameters, are evaluated using a Monte Carlo analysis. We conclude that customized lenses should give improved retinal image quality despite the random errors resulting from IOL insertion. PMID:22574257

  16. In vivo tracking of human adipose-derived stem cells labeled with ferumoxytol in rats with middle cerebral artery occlusion by magnetic resonance imaging

    PubMed Central

    Yin, Yan; Zhou, Xiang; Guan, Xin; Liu, Yang; Jiang, Chang-bin; Liu, Jing

    2015-01-01

    Ferumoxytol, an iron replacement product, is a new type of superparamagnetic iron oxide approved by the US Food and Drug Administration. Herein, we assessed the feasibility of tracking transplanted human adipose-derived stem cells labeled with ferumoxytol in middle cerebral artery occlusion-injured rats by 3.0 T MRI in vivo. 1 × 104 human adipose-derived stem cells labeled with ferumoxytol-heparin-protamine were transplanted into the brains of rats with middle cerebral artery occlusion. Neurologic impairment was scored at 1, 7, 14, and 28 days after transplantation. T2-weighted imaging and enhanced susceptibility-weighted angiography were used to observe transplanted cells. Results of imaging tests were compared with results of Prussian blue staining. The modified neurologic impairment scores were significantly lower in rats transplanted with cells at all time points except 1 day post-transplantation compared with rats without transplantation. Regions with hypointense signals on T2-weighted and enhanced susceptibility-weighted angiography images corresponded with areas stained by Prussian blue, suggesting the presence of superparamagnetic iron oxide particles within the engrafted cells. Enhanced susceptibility-weighted angiography image exhibited better sensitivity and contrast in tracing ferumoxytol-heparin-protamine-labeled human adipose-derived stem cells compared with T2-weighted imaging in routine MRI. PMID:26199607

  17. Differential gloss quality scale experiment update: an appearance-based image quality standard initiative (INCITS W1.1)

    NASA Astrophysics Data System (ADS)

    Ng, Yee S.; Kuo, Chunghui; Maggard, Eric; Mashtare, Dale; Morris, Peter; Farnand, Susan

    2007-01-01

    Surface characteristics of a printed sample command a parallel group of visual attributes determining perceived image quality beyond color, and they manifest themselves through various perceived gloss features such as differential gloss, gloss granularity, gloss mottle, etc. Extending from the scope of ISO19799 with limited range of gloss level and printing technologies, the objective of this study is to derive an appearance-based differential gloss quality scale ranging from very low gloss level to very high gloss level composed by various printing technology/substrate combinations. Three psychophysical experiment procedures were proposed including the quality ruler method, pair comparison, and interval scaling with two anchor stimuli, where the pair comparison process was subsequently dropped because of the concern of experiment complexity and data consistency after preliminary trial study. In this paper, we will compare the obtained average quality scale after mapping to the sharpness quality ruler with the average perceived differential gloss via the interval scale. Our numerical analysis indicates a general inverse relationship between the perceived image quality and the gloss variation on an image.

  18. Fusion and quality analysis for remote sensing images using contourlet transform

    NASA Astrophysics Data System (ADS)

    Choi, Yoonsuk; Sharifahmadian, Ershad; Latifi, Shahram

    2013-05-01

    Recent developments in remote sensing technologies have provided various images with high spatial and spectral resolutions. However, multispectral images have low spatial resolution and panchromatic images have low spectral resolution. Therefore, image fusion techniques are necessary to improve the spatial resolution of spectral images by injecting spatial details of high-resolution panchromatic images. The objective of image fusion is to provide useful information by improving the spatial resolution and the spectral information of the original images. The fusion results can be utilized in various applications, such as military, medical imaging, and remote sensing. This paper addresses two issues in image fusion: i) image fusion method and ii) quality analysis of fusion results. First, a new contourlet-based image fusion method is presented, which is an improvement over the wavelet-based fusion. This fusion method is then applied to a case study to demonstrate its fusion performance. Fusion framework and scheme used in the study are discussed in detail. Second, quality analysis for the fusion results is discussed. We employed various quality metrics in order to analyze the fusion results both spatially and spectrally. Our results indicate that the proposed contourlet-based fusion method performs better than the conventional wavelet-based fusion methods.

  19. Body image and college women's quality of life: The importance of being self-compassionate.

    PubMed

    Duarte, Cristiana; Ferreira, Cláudia; Trindade, Inês A; Pinto-Gouveia, José

    2015-06-01

    This study explored self-compassion as a mediator between body dissatisfaction, social comparison based on body image and quality of life in 662 female college students. Path analysis revealed that while controlling for body mass index, self-compassion mediated the impact of body dissatisfaction and unfavourable social comparisons on psychological quality of life. The path model accounted for 33?per cent of psychological quality of life variance. Findings highlight the importance of self-compassion as a mechanism that may operate on the association between negative body image evaluations and young women's quality of life. PMID:26032792

  20. Light-leaking region segmentation of FOG fiber based on quality evaluation of infrared image

    NASA Astrophysics Data System (ADS)

    Liu, Haoting; Wang, Wei; Gao, Feng; Shan, Lianjie; Ma, Yuzhou; Ge, Wenqian

    2014-07-01

    To improve the assembly reliability of Fiber Optic Gyroscope (FOG), a light leakage detection system and method is developed. First, an agile movement control platform is designed to implement the pose control of FOG optical path component in 6 Degrees of Freedom (DOF). Second, an infrared camera is employed to capture the working state images of corresponding fibers in optical path component after the manual assembly of FOG; therefore the entire light transmission process of key sections in light-path can be recorded. Third, an image quality evaluation based region segmentation method is developed for the light leakage images. In contrast to the traditional methods, the image quality metrics, including the region contrast, the edge blur, and the image noise level, are firstly considered to distinguish the image characters of infrared image; then the robust segmentation algorithms, including graph cut and flood fill, are all developed for region segmentation according to the specific image quality. Finally, after the image segmentation of light leakage region, the typical light-leaking type, such as the point defect, the wedge defect, and the surface defect can be identified. By using the image quality based method, the applicability of our proposed system can be improved dramatically. Many experiment results have proved the validity and effectiveness of this method.

  1. Nondestructive spectroscopic and imaging techniques for quality evaluation and assessment of fish and fish products.

    PubMed

    He, Hong-Ju; Wu, Di; Sun, Da-Wen

    2015-01-01

    Nowadays, people have increasingly realized the importance of acquiring high quality and nutritional values of fish and fish products in their daily diet. Quality evaluation and assessment are always expected and conducted by using rapid and nondestructive methods in order to satisfy both producers and consumers. During the past two decades, spectroscopic and imaging techniques have been developed to nondestructively estimate and measure quality attributes of fish and fish products. Among these noninvasive methods, visible/near-infrared (VIS/NIR) spectroscopy, computer/machine vision, and hyperspectral imaging have been regarded as powerful and effective analytical tools for fish quality analysis and control. VIS/NIR spectroscopy has been widely applied to determine intrinsic quality characteristics of fish samples, such as moisture, protein, fat, and salt. Computer/machine vision on the other hand mainly focuses on the estimation of external features like color, weight, size, and surface defects. Recently, by incorporating both spectroscopy and imaging techniques in one system, hyperspectral imaging cannot only measure the contents of different quality attributes simultaneously, but also obtain the spatial distribution of such attributes when the quality of fish samples are evaluated and measured. This paper systematically reviews the research advances of these three nondestructive optical techniques in the application of fish quality evaluation and determination and discuss future trends in the developments of nondestructive technologies for further quality characterization in fish and fish products. PMID:24915393

  2. Impact of Computed Tomography Image Quality on Image-Guided Radiation Therapy Based on Soft Tissue Registration

    SciTech Connect

    Morrow, Natalya V.; Lawton, Colleen A.; Qi, X. Sharon; Li, X. Allen

    2012-04-01

    Purpose: In image-guided radiation therapy (IGRT), different computed tomography (CT) modalities with varying image quality are being used to correct for interfractional variations in patient set-up and anatomy changes, thereby reducing clinical target volume to the planning target volume (CTV-to-PTV) margins. We explore how CT image quality affects patient repositioning and CTV-to-PTV margins in soft tissue registration-based IGRT for prostate cancer patients. Methods and Materials: Four CT-based IGRT modalities used for prostate RT were considered in this study: MV fan beam CT (MVFBCT) (Tomotherapy), MV cone beam CT (MVCBCT) (MVision; Siemens), kV fan beam CT (kVFBCT) (CTVision, Siemens), and kV cone beam CT (kVCBCT) (Synergy; Elekta). Daily shifts were determined by manual registration to achieve the best soft tissue agreement. Effect of image quality on patient repositioning was determined by statistical analysis of daily shifts for 136 patients (34 per modality). Inter- and intraobserver variability of soft tissue registration was evaluated based on the registration of a representative scan for each CT modality with its corresponding planning scan. Results: Superior image quality with the kVFBCT resulted in reduced uncertainty in soft tissue registration during IGRT compared with other image modalities for IGRT. The largest interobserver variations of soft tissue registration were 1.1 mm, 2.5 mm, 2.6 mm, and 3.2 mm for kVFBCT, kVCBCT, MVFBCT, and MVCBCT, respectively. Conclusions: Image quality adversely affects the reproducibility of soft tissue-based registration for IGRT and necessitates a careful consideration of residual uncertainties in determining different CTV-to-PTV margins for IGRT using different image modalities.

  3. The effect of stereoscopic display luminance and ambient illuminance on physiological measurement and image quality

    NASA Astrophysics Data System (ADS)

    Wang, Pei-Chia; Chen, Kuan-Yu; Hwang, Sheue-Ling; Chen, Chin-Sen

    2011-06-01

    When people watch 3D-Ready TV, the display luminance as well as the ambient illuminace is important factors for image quality and physiological comfort. In this research, a human factors experiment on a stereoscopic display was conducted. The result showed that display luminance affected subjective comfort evaluation and image quality evaluation. The effect of ambient illuminance also influenced objective asthenopia index (CFF), subjective comfort evaluation and viewers' image quality evaluation of watching 3D static pictures. However, the main effects of display luminance, ambient illuminance, and their interaction effect were not significant on objective physiological measurement (HRV). Among the six combination levels of display luminance and ambient illuminance, viewers felt more comfortable and got the best image quality in the high levels of display luminance and ambient illuminance. The outcome of the experiment is expected to find out the optimal display luminance and ambient illuminance combination level for designers' guidelines and users' references as viewing 3D displays.

  4. Evaluation of image quality and factor for international telepathology through the Internet

    NASA Astrophysics Data System (ADS)

    Yagi, Yukako; Azumi, Norio; Elsayed, Alaa M.; Mun, Seong K.

    1997-05-01

    In the telepathology, rendering devices significantly influence the perceived image quality. If the resolution and color depth are reduced beyond a certain point, however, it is not possible to obtain images which can be used in telepathology even in an ideal situation. With this in mind, we evaluated image quality, compression, size and rates of data exchange with several histological cases on several kinds of systems for our International Consortium for Internet Telepathology (ICIT) project. The ICIT network uses widely available nonpropriety hardware and software with the Internet as a means of communication.In this study, we discuss the effective image acquisition methods for telepathology. To evaluate microscopic images, various resolution size were used. The images were also evaluated at different JPEG compression ratio, including zero compression, and different format. To evaluate an entire glass slide image, a scanner in transparency mode and an NTSC camera were used. Every case showed similar results. For he microscopic image, although the high resolution images, such as 2k X 1.5k or higher, contain more diagnostic information than lower resolution images; sufficient data was retained in the latter that it does not appear to negatively effect diagnosis. The circumstance and condition for image acquisition, such as specimen thickness or dast of glass slide, are most influenced on the highest image resolution. Usually, we use 5-10 images/case for a telepathology conference. To see all images of a case at a glance before detailed observation, or to switch to the other images immediately, a lower resolution,such as 1k X 0.7k is useful. For the entire glass slide, the reviewer could select the desired area by scanner; however, selecting it by the NTSC camera, was not easy to do. On the monitor, the scanned image has almost the same information as the microscopic image captured by the NTSC camera with 2x objective lens. To ge ta high enough quality image, the important factors are correct usage of the microscope and the condition of glass slide, not only high performance equipment.Since we have been using the Internet as the communication medium, we selected 1024 X 774 and 640 X 480 with 1/7-1/15 compressed image for microscopic image and 2700 dpi scanned image for entire glass slide. For the static image telepathology, the most important image is the low power image such as the entire specimen. High resolution images such as 3k X 2k are also useful for different purpose such as publication.

  5. TU-F-9A-01: Balancing Image Quality and Dose in Radiography

    SciTech Connect

    Peck, D; Pasciak, A

    2014-06-15

    Emphasis is often placed on minimizing radiation dose in diagnostic imaging without a complete consideration of the effect on image quality, especially those that affect diagnostic accuracy. This session will include a patient image-based review of diagnostic quantities important to radiologists in conventional radiography, including the effects of body habitus, age, positioning, and the clinical indication of the exam. The relationships between image quality, radiation dose, and radiation risk will be discussed, specifically addressing how these factors are affected by image protocols and acquisition parameters and techniques. This session will also discuss some of the actual and perceived radiation risk associated with diagnostic imaging. Regardless if the probability for radiation-induced cancer is small, the fear associated with radiation persists. Also when a risk has a benefit to an individual or to society, the risk may be justified with respect to the benefit. But how do you convey the risks and the benefits to people? This requires knowledge of how people perceive risk and how to communicate the risk and the benefit to different populations. In this presentation the sources of errors in estimating risk from radiation and some methods used to convey risks are reviewed. Learning Objectives: Understand the image quality metrics that are clinically relevant to radiologists. Understand how acquisition parameters and techniques affect image quality and radiation dose in conventional radiology. Understand the uncertainties in estimates of radiation risk from imaging exams. Learn some methods for effectively communicating radiation risk to the public.

  6. Color image quality assessment with biologically inspired feature and machine learning

    NASA Astrophysics Data System (ADS)

    Deng, Cheng; Tao, Dacheng

    2010-07-01

    In this paper, we present a new no-reference quality assessment metric for color images by using biologically inspired features (BIFs) and machine learning. In this metric, we first adopt a biologically inspired model to mimic the visual cortex and represent a color image based on BIFs which unifies color units, intensity units and C1 units. Then, in order to reduce the complexity and benefit the classification, the high dimensional features are projected to a low dimensional representation with manifold learning. Finally, a multiclass classification process is performed on this new low dimensional representation of the image and the quality assessment is based on the learned classification result in order to respect the one of the human observers. Instead of computing a final note, our method classifies the quality according to the quality scale recommended by the ITU. The preliminary results show that the developed metric can achieve good quality evaluation performance.

  7. Recent developments and applications of hyperspectral imaging for quality evaluation of agricultural products: a review.

    PubMed

    Liu, Dan; Zeng, Xin-An; Sun, Da-Wen

    2015-01-01

    Food quality and safety is the foremost issue for consumers, retailers as well as regulatory authorities. Most quality parameters are assessed by traditional methods, which are time consuming, laborious, and associated with inconsistency and variability. Non-destructive methods have been developed to objectively measure quality attributes for various kinds of food. In recent years, hyperspectral imaging (HSI) has matured into one of the most powerful tools for quality evaluation of agricultural and food products. HSI allows characterization of a sample's chemical composition (spectroscopic component) and external features (imaging component) in each point of the image with full spectral information. In order to track the latest research developments of this technology, this paper gives a detailed overview of the theory and fundamentals behind this technology and discusses its applications in the field of quality evaluation of agricultural products. Additionally, future potentials of HSI are also reported. PMID:24915395

  8. Scientific assessment of the quality of OSIRIS images

    NASA Astrophysics Data System (ADS)

    Tubiana, C.; Güttler, C.; Kovacs, G.; Bertini, I.; Bodewits, D.; Fornasier, S.; Lara, L.; La Forgia, F.; Magrin, S.; Pajola, M.; Sierks, H.; Barbieri, C.; Lamy, P. L.; Rodrigo, R.; Koschny, D.; Rickman, H.; Keller, H. U.; Agarwal, J.; A'Hearn, M. F.; Barucci, M. A.; Bertaux, J.-L.; Besse, S.; Boudreault, S.; Cremonese, G.; Da Deppo, V.; Davidsson, B.; Debei, S.; De Cecco, M.; El-Maarry, M. R.; Fulle, M.; Groussin, O.; Gutiérrez-Marques, P.; Gutiérrez, P. J.; Hoekzema, N.; Hofmann, M.; Hviid, S. F.; Ip, W.-H.; Jorda, L.; Knollenberg, J.; Kramm, J.-R.; Kührt, E.; Küppers, M.; Lazzarin, M.; Lopez Moreno, J. J.; Marzari, F.; Massironi, M.; Michalik, H.; Moissl, R.; Naletto, G.; Oklay, N.; Scholten, F.; Shi, X.; Thomas, N.; Vincent, J.-B.

    2015-11-01

    Context. OSIRIS, the scientific imaging system onboard the ESA Rosetta spacecraft, has been imaging the nucleus of comet 67P/Churyumov-Gerasimenko and its dust and gas environment since March 2014. The images serve different scientific goals, from morphology and composition studies of the nucleus surface, to the motion and trajectories of dust grains, the general structure of the dust coma, the morphology and intensity of jets, gas distribution, mass loss, and dust and gas production rates. Aims: We present the calibration of the raw images taken by OSIRIS and address the accuracy that we can expect in our scientific results based on the accuracy of the calibration steps that we have performed. Methods: We describe the pipeline that has been developed to automatically calibrate the OSIRIS images. Through a series of steps, radiometrically calibrated and distortion corrected images are produced and can be used for scientific studies. Calibration campaigns were run on the ground before launch and throughout the years in flight to determine the parameters that are used to calibrate the images and to verify their evolution with time. We describe how these parameters were determined and we address their accuracy. Results: We provide a guideline to the level of trust that can be put into the various studies performed with OSIRIS images, based on the accuracy of the image calibration.

  9. ANALYZING WATER QUALITY WITH IMAGES ACQUIRED FROM AIRBORNE SENSORS

    EPA Science Inventory

    Monitoring different parameters of water quality can be a time consuming and expensive activity. However, the use of airborne light-sensitive (optical) instruments may enhance the abilities of resource managers to monitor water quality in rivers in a timely and cost-effective ma...

  10. Predicted image quality of a CMOS APS X-ray detector across a range of mammographic beam qualities

    NASA Astrophysics Data System (ADS)

    Konstantinidis, A.

    2015-09-01

    Digital X-ray detectors based on Complementary Metal-Oxide- Semiconductor (CMOS) Active Pixel Sensor (APS) technology have been introduced in the early 2000s in medical imaging applications. In a previous study the X-ray performance (i.e. presampling Modulation Transfer Function (pMTF), Normalized Noise Power Spectrum (NNPS), Signal-to-Noise Ratio (SNR) and Detective Quantum Efficiency (DQE)) of the Dexela 2923MAM CMOS APS X-ray detector was evaluated within the mammographic energy range using monochromatic synchrotron radiation (i.e. 17-35 keV). In this study image simulation was used to predict how the mammographic beam quality affects image quality. In particular, the experimentally measured monochromatic pMTF, NNPS and SNR parameters were combined with various mammographic spectral shapes (i.e. Molybdenum/Molybdenum (Mo/Mo), Rhodium/Rhodium (Rh/Rh), Tungsten/Aluminium (W/Al) and Tungsten/Rhodium (W/Rh) anode/filtration combinations at 28 kV). The image quality was measured in terms of Contrast-to-Noise Ratio (CNR) using a synthetic breast phantom (4 cm thick with 50% glandularity). The results can be used to optimize the imaging conditions in order to minimize patient's Mean Glandular Dose (MGD).

  11. The quest for 'diagnostically lossless' medical image compression: a comparative study of objective quality metrics for compressed medical images

    NASA Astrophysics Data System (ADS)

    Kowalik-Urbaniak, Ilona; Brunet, Dominique; Wang, Jiheng; Koff, David; Smolarski-Koff, Nadine; Vrscay, Edward R.; Wallace, Bill; Wang, Zhou

    2014-03-01

    Our study, involving a collaboration with radiologists (DK,NSK) as well as a leading international developer of medical imaging software (AGFA), is primarily concerned with improved methods of assessing the diagnostic quality of compressed medical images and the investigation of compression artifacts resulting from JPEG and JPEG2000. In this work, we compare the performances of the Structural Similarity quality measure (SSIM), MSE/PSNR, compression ratio CR and JPEG quality factor Q, based on experimental data collected in two experiments involving radiologists. An ROC and Kolmogorov-Smirnov analysis indicates that compression ratio is not always a good indicator of visual quality. Moreover, SSIM demonstrates the best performance, i.e., it provides the closest match to the radiologists' assessments. We also show that a weighted Youden index1 and curve tting method can provide SSIM and MSE thresholds for acceptable compression ratios.

  12. No-reference image quality assessment based on log-derivative statistics of natural scenes

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Chandler, Damon M.

    2013-10-01

    We propose an efficient blind/no-reference image quality assessment algorithm using a log-derivative statistical model of natural scenes. Our method, called DErivative Statistics-based QUality Evaluator (DESIQUE), extracts image quality-related statistical features at two image scales in both the spatial and frequency domains. In the spatial domain, normalized pixel values of an image are modeled in two ways: pointwise-based statistics for single pixel values and pairwise-based log-derivative statistics for the relationship of pixel pairs. In the frequency domain, log-Gabor filters are used to extract the fine scales of the image, which are also modeled by the log-derivative statistics. All of these statistics can be fitted by a generalized Gaussian distribution model, and the estimated parameters are fed into combined frameworks to estimate image quality. We train our models on the LIVE database by using optimized support vector machine learning. Experiment results tested on other databases show that the proposed algorithm not only yields a substantial improvement in predictive performance as compared to other state-of-the-art no-reference image quality assessment methods, but also maintains a high computational efficiency.

  13. A Hyperspectral Imaging System for Quality Detection of Pickles

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A hyperspectral imaging system in simultaneous reflectance (400-675 nm) and transmittance (675-1000 nm) modes was developed for detection of hollow or bloater damage on whole pickles. Hyperspectral reflectance and transmittance images were acquired from normal and bloated whole pickle samples collec...

  14. Image Quality Assessment Based on Inter-Patch and Intra-Patch Similarity

    PubMed Central

    Zhou, Fei; Lu, Zongqing; Wang, Can; Sun, Wen; Xia, Shu-Tao; Liao, Qingmin

    2015-01-01

    In this paper, we propose a full-reference (FR) image quality assessment (IQA) scheme, which evaluates image fidelity from two aspects: the inter-patch similarity and the intra-patch similarity. The scheme is performed in a patch-wise fashion so that a quality map can be obtained. On one hand, we investigate the disparity between one image patch and its adjacent ones. This disparity is visually described by an inter-patch feature, where the hybrid effect of luminance masking and contrast masking is taken into account. The inter-patch similarity is further measured by modifying the normalized correlation coefficient (NCC). On the other hand, we also attach importance to the impact of image contents within one patch on the IQA problem. For the intra-patch feature, we consider image curvature as an important complement of image gradient. According to local image contents, the intra-patch similarity is measured by adaptively comparing image curvature and gradient. Besides, a nonlinear integration of the inter-patch and intra-patch similarity is presented to obtain an overall score of image quality. The experiments conducted on six publicly available image databases show that our scheme achieves better performance in comparison with several state-of-the-art schemes. PMID:25793282

  15. TH-A-16A-01: Image Quality for the Radiation Oncology Physicist: Review of the Fundamentals and Implementation

    SciTech Connect

    Seibert, J; Imbergamo, P

    2014-06-15

    The expansion and integration of diagnostic imaging technologies such as On Board Imaging (OBI) and Cone Beam Computed Tomography (CBCT) into radiation oncology has required radiation oncology physicists to be responsible for and become familiar with assessing image quality. Unfortunately many radiation oncology physicists have had little or no training or experience in measuring and assessing image quality. Many physicists have turned to automated QA analysis software without having a fundamental understanding of image quality measures. This session will review the basic image quality measures of imaging technologies used in the radiation oncology clinic, such as low contrast resolution, high contrast resolution, uniformity, noise, and contrast scale, and how to measure and assess them in a meaningful way. Additionally a discussion of the implementation of an image quality assurance program in compliance with Task Group recommendations will be presented along with the advantages and disadvantages of automated analysis methods. Learning Objectives: Review and understanding of the fundamentals of image quality. Review and understanding of the basic image quality measures of imaging modalities used in the radiation oncology clinic. Understand how to implement an image quality assurance program and to assess basic image quality measures in a meaningful way.

  16. Three-dimensional Statistical Modeling for Image Quality Improvements in Multi-Slice Helical CT

    E-print Network

    the application of Bayesian iterative algorithms to real 3D helical data to demonstrate significant image quality, statistical iterative re- construction (IR) techniques appear particularly promising since they provide applications arise, however, in which characteristics of the scanner hardware places a limit on quality

  17. A Semi-Automatic Coronary Artery Segmentation Framework Using Mechanical Simulation.

    PubMed

    Cai, Ken; Yang, Rongqian; Li, Lihua; Ou, Shanxing; Chen, Yuke; Dou, Jianhong

    2015-10-01

    CVD (cardiovascular disease) is one of the biggest threats to human beings nowadays. An early and quantitative diagnosis of CVD is important in extending lifespan and improving people's life quality. Coronary artery stenosis can prevent CVD. To diagnose the degree of stenosis, the inner diameter of coronary artery needs to be measured. To achieve such measurement, the coronary artery is segmented by using a method that is based on morphology and the continuity between computed tomography image slices. A centerline extraction method based on mechanical simulation is proposed. This centerline extraction method can figure out a basic framework of the coronary artery by simulating pixel dots of the artery image into mass points. Such mass points have tensile forces, with which the outer pixel dots can be drawn to the center. Subsequently, the centerline of the coronary artery can be outlined by using the local line-fitting method. Finally, the nearest point method is adopted to measure the inner diameter. Experimental results showed that the methods proposed in this paper can precisely extract the centerline of the coronary artery and can accurately measure its inner diameter, thereby providing a basis for quantitative diagnosis of coronary artery stenosis. PMID:26310950

  18. Dose reduction and image quality optimizations in CT of pediatric and adult patients: phantom studies

    NASA Astrophysics Data System (ADS)

    Jeon, P.-H.; Lee, C.-L.; Kim, D.-H.; Lee, Y.-J.; Jeon, S.-S.; Kim, H.-J.

    2014-03-01

    Multi-detector computed tomography (MDCT) can be used to easily and rapidly perform numerous acquisitions, possibly leading to a marked increase in the radiation dose to individual patients. Technical options dedicated to automatically adjusting the acquisition parameters according to the patient's size are of specific interest in pediatric radiology. A constant tube potential reduction can be achieved for adults and children, while maintaining a constant detector energy fluence. To evaluate radiation dose, the weighted CT dose index (CTDIw) was calculated based on the CT dose index (CTDI) measured using an ion chamber, and image noise and image contrast were measured from a scanned image to evaluate image quality. The dose-weighted contrast-to-noise ratio (CNRD) was calculated from the radiation dose, image noise, and image contrast measured from a scanned image. The noise derivative (ND) is a quality index for dose efficiency. X-ray spectra with tube voltages ranging from 80 to 140 kVp were used to compute the average photon energy. Image contrast and the corresponding contrast-to-noise ratio (CNR) were determined for lesions of soft tissue, muscle, bone, and iodine relative to a uniform water background, as the iodine contrast increases at lower energy (i.e., k-edge of iodine is 33 keV closer to the beam energy) using mixed water-iodine contrast normalization (water 0, iodine 25, 100, 200, and 1000 HU, respectively). The proposed values correspond to high quality images and can be reduced if only high-contrast organs are assessed. The potential benefit of lowering the tube voltage is an improved CNRD, resulting in a lower radiation dose and optimization of image quality. Adjusting the tube potential in abdominal CT would be useful in current pediatric radiography, where the choice of X-ray techniques generally takes into account the size of the patient as well as the need to balance the conflicting requirements of diagnostic image quality and radiation dose optimization.

  19. Investigation of diagnostic and image quality attributes: comparison of screen-film to CR mammography

    NASA Astrophysics Data System (ADS)

    Fletcher-Heath, Lynn; Richards, Anne; Ryan-Kron, Susan

    2006-03-01

    Digital mammography is advancing into an arena where analog has long been the gold standard. Direct digital systems may not be the favored solution for a particular site while computed radiography (CR) mammography, remains unproven worldwide. This pilot study responds to the growing desire to acquire and display digital mammographic images by exploring the acceptability of CR mammography. Images representing a range of breast tissue types were collected from 49 subjects (17 screening; 32 diagnostic) at four clinical sites. Comparison views were collected on the same breast, under the same compression, using automatic exposure control on state-of-the-art film systems followed by CR. CR images were processed and printed to a mammography printer for hard copy feature comparison. Each image pair in the study was evaluated according to 13 image quality attributes covering noise, contrast, sharpness, and image quality in the overall captured images as well as in each of several particular breast regions (periphery and skin-line, parenchyma and fatty tissue). A rating scale from 1 to 5 was used (strong preference for film=1, strong preference for CR=5). Twelve experienced mammographers at four clinical sites scored a subset of the 49 cases for a total of 64 image pair readings. There were 64 ratings for each of 13 image quality attributes for all cases and, an additional series of scores (four or five attribute ratings) for each abnormality in the category of mass, architectural distortion and microcalcification, for a total of 1069 scores. Based on the pilot study results, it was suggested that CR was equivalent or preferred to conventional screen-film for overall image quality (38% scored 3; 46% scored >3), image contrast (27% scored 3; 59% scored >3) and sharpness (28% scored 3; 50% scored >3). No preference was found when assessing noise. This pilot study also suggested that diagnostic quality was maintained in assessing abnormalities for attributes necessary to evaluate masses and microcalcifications as compared to screen-film.

  20. Carotid Artery Atherosclerosis: Effect of Intensive Lipid Therapy on the Vasa Vasorum—Evaluation by Using Dynamic Contrast-enhanced MR Imaging

    PubMed Central

    Dong, Li; Chen, Huijun; Chu, Baocheng; Underhill, Hunter R.; Neradilek, Moni Blazej; Hatsukami, Thomas S.; Yuan, Chun; Zhao, Xue-Qiao

    2011-01-01

    Purpose: To investigate whether short-term, intensive lipid therapy leads to changes in microvascular characteristics, as measured by using dynamic contrast material–enhanced (DCE) magnetic resonance (MR) imaging. Materials and Methods: Institutional review board approval and informed consent were obtained for this HIPAA-compatible study. Subjects with established coronary artery disease or carotid artery stenosis of 15% or greater determined by using ultrasonography and with levels of apolipoprotein B of 120 mg/dL (1.2 g/L) or greater were enrolled in an ongoing study (clinical trial NCT00715273). All received intensive lipid therapy to achieve targeted high- and low-density lipoprotein cholesterol levels and underwent serial serum monitoring including high-sensitivity C-reactive protein (HsCRP) level measurements. Carotid artery MR imaging examinations including morphologic and DCE MR images were obtained at baseline and 1 year after treatment. In subjects with advanced lesions (>2 mm thick), MR image analysis was performed, including measurement of lipid-rich necrotic core size and kinetic modeling of DCE MR images to assess changes in the transfer constant (Ktrans). The differences in Ktrans between baseline and 1-year follow-up were compared by using the Wilcoxon signed rank test, and associations were assessed by using the Spearman rank correlation coefficient. Results: Twenty-eight subjects with interpretable DCE MR imaging results at both baseline and 1-year follow-up were included. After 1 year of treatment, a significant reduction was found in mean Ktrans (0.085 min?1 ± 0.037 [standard deviation] to 0.067 min?1 ± 0.028, P = .02). Reduction in Ktrans was not significantly correlated with observed reductions in lipid-rich necrotic core size or reductions in HsCRP level. Conclusion: These findings suggest that DCE MR imaging may be a useful imaging method for the assessment of the therapeutic response of the vasa vasorum in patients with atherosclerotic plaque. Clinical trial registration no. NCT00715273. © RSNA, 2011 PMID:21493792

  1. Second Harmonic Imaging improves Echocardiograph Quality on board the International Space Station

    NASA Technical Reports Server (NTRS)

    Garcia, Kathleen; Sargsyan, Ashot; Hamilton, Douglas; Martin, David; Ebert, Douglas; Melton, Shannon; Dulchavsky, Scott

    2008-01-01

    Ultrasound (US) capabilities have been part of the Human Research Facility (HRF) on board the International Space Station (ISS) since 2001. The US equipment on board the ISS includes a first-generation Tissue Harmonic Imaging (THI) option. Harmonic imaging (HI) is the second harmonic response of the tissue to the ultrasound beam and produces robust tissue detail and signal. Since this is a first-generation THI, there are inherent limitations in tissue penetration. As a breakthrough technology, HI extensively advanced the field of ultrasound. In cardiac applications, it drastically improves endocardial border detection and has become a common imaging modality. U.S. images were captured and stored as JPEG stills from the ISS video downlink. US images with and without harmonic imaging option were randomized and provided to volunteers without medical education or US skills for identification of endocardial border. The results were processed and analyzed using applicable statistical calculations. The measurements in US images using HI improved measurement consistency and reproducibility among observers when compared to fundamental imaging. HI has been embraced by the imaging community at large as it improves the quality and data validity of US studies, especially in difficult-to-image cases. Even with the limitations of the first generation THI, HI improved the quality and measurability of many of the downlinked images from the ISS and should be an option utilized with cardiac imaging on board the ISS in all future space missions.

  2. Image and Diagnosis Quality of X-Ray Image Transmission via Cell Phone Camera: A Project Study Evaluating Quality and Reliability

    PubMed Central

    Heck, Andreas; Hadizadeh, Dariusch R.; Weber, Oliver; Gräff, Ingo; Burger, Christof; Montag, Mareen; Koerfer, Felix; Kabir, Koroush

    2012-01-01

    Introduction Developments in telemedicine have not produced any relevant benefits for orthopedics and trauma surgery to date. For the present project study, several parameters were examined during assessment of x-ray images, which had been photographed and transmitted via cell phone. Materials and Methods A total of 100 x-ray images of various body regions were photographed with a Nokia cell phone and transmitted via email or MMS. Next, the transmitted photographs were reviewed on a laptop computer by five medical specialists and assessed regarding quality and diagnosis. Results Due to their poor quality, the transmitted MMS images could not be evaluated and this path of transmission was therefore excluded. Mean size of transmitted x-ray email images was 394 kB (range: 265–590 kB, SD ±59), average transmission time was 3.29 min ±8 (CI 95%: 1.7–4.9). Applying a score from 1–10 (very poor - excellent), mean image quality was 5.8. In 83.2±4% (mean value ± SD) of cases (median 82; 80–89%), there was agreement between final diagnosis and assessment by the five medical experts who had received the images. However, there was a markedly low concurrence ratio in the thoracic area and in pediatric injuries. Discussion While the rate of accurate diagnosis and indication for surgery was high with a concurrence ratio of 83%, considerable differences existed between the assessed regions, with lowest values for thoracic images. Teleradiology is a cost-effective, rapid method which can be applied wherever wireless cell phone reception is available. In our opinion, this method is in principle suitable for clinical use, enabling the physician on duty to agree on appropriate measures with colleagues located elsewhere via x-ray image transmission on a cell phone. PMID:23082108

  3. USING INFRARED ILLUMINATION TO IMPROVE EYE & FACE TRACKING IN LOW QUALITY VIDEO IMAGES

    E-print Network

    Adler, Andy

    USING INFRARED ILLUMINATION TO IMPROVE EYE & FACE TRACKING IN LOW QUALITY VIDEO IMAGES R. Youmaran and face tracking algorithm using active infrared (IR) illumination. Most eye trackers based on active IR can robustly detect faces and track eyes in a sequence of images under variable lighting conditions

  4. Can we ID from CCTV: image quality in digital CCTV and face identification performance

    E-print Network

    Sasse, Angela

    Can we ID from CCTV: image quality in digital CCTV and face identification performance Hina U, UK ABSTRACT CCTV is used for an increasing number of purposes, and the new generation of digital of untrained viewers to identify faces from digital CCTV images. The task required 80 participants to identify

  5. The impact of skull bone intensity on the quality of compressed CT neuro images

    E-print Network

    Wang, Zhou

    The impact of skull bone intensity on the quality of compressed CT neuro images Ilona Kowalik of the sharp skull edges present in CT neuro images on JPEG and JPEG2000 lossy compression. We conjecture that this atypical effect is caused by the sharp edges between the skull bone and the background regions as well

  6. JPEG vs. JPEG2000: An Objective Comparison of Image Encoding Quality

    E-print Network

    Winkler, Stefan

    JPEG vs. JPEG2000: An Objective Comparison of Image Encoding Quality Farzad Ebrahimi, Matthieu comparison, we compress a set of 29 test images with two JPEG encoders (Adobe Photoshop and IrfanView) and three JPEG2000 encoders (JasPer, Kakadu, and IrfanView) at various compression ratios. We compute

  7. Color Image Quality Metric S-CIELAB and Its Application on Halftone Texture Xuemei Zhang

    E-print Network

    Wandell, Brian A.

    Color Image Quality Metric S-CIELAB and Its Application on Halftone Texture Visibility Xuemei Zhang@white.stanford.edu Abstract We describe experimental tests of a spatial extension to the CIELAB color metric for measuring color reproduction errors of digital images. The standard CIELAB E metric is suitable for use on large

  8. Image-quality assessment of monochrome monitors for medical soft copy display

    NASA Astrophysics Data System (ADS)

    Weibrecht, Martin; Spekowius, Gerhard; Quadflieg, Peter; Blume, Hartwig R.

    1997-05-01

    Soft-copy presentation of medical images is becoming part of the medical routine as more and more health care facilities are converted to digital filmless hospital and radiological information management. To provide optimal image quality, display systems must be incorporated when assessing the overall system image quality. We developed a method to accomplish this. The proper working of the method is demonstrated with the analysis of four different monochrome monitors. We determined display functions and veiling glare with a high-performance phot