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Sample records for artery image quality

  1. Improving Image Quality of Bronchial Arteries with Virtual Monochromatic Spectral CT Images

    PubMed Central

    Ma, Guangming; He, Taiping; Yu, Yong; Duan, Haifeng; Yang, Chuangbo

    2016-01-01

    Objective To evaluate the clinical value of using monochromatic images in spectral CT pulmonary angiography to improve image quality of bronchial arteries. Methods We retrospectively analyzed the chest CT images of 38 patients who underwent contrast-enhanced spectral CT. These images included a set of 140kVp polychromatic images and the default 70keV monochromatic images. Using the standard Gemstone Spectral Imaging (GSI) viewer on an advanced workstation (AW4.6,GE Healthcare), an optimal energy level (in keV) for obtaining the best contrast-to-noise ratio (CNR) for the artery could be automatically obtained. The signal-to-noise ratio (SNR), CNR and objective image quality score (1–5) for these 3 image sets (140kVp, 70keV and optimal energy level) were obtained and, statistically compared. The image quality score consistency between the two observers was also evaluated using Kappa test. Results The optimal energy levels for obtaining the best CNR were 62.58±2.74keV.SNR and CNR from the 140kVp polychromatic, 70keV and optimal keV monochromatic images were (16.44±5.85, 13.24±5.52), (20.79±7.45, 16.69±6.27) and (24.9±9.91, 20.53±8.46), respectively. The corresponding subjective image quality scores were 1.97±0.82, 3.24±0.75, and 4.47±0.60. SNR, CNR and subjective scores had significant difference among groups (all p<0.001). The optimal keV monochromatic images were superior to the 70keV monochromatic and 140kVp polychromatic images, and there was high agreement between the two observers on image quality score (kappa>0.80). Conclusions Virtual monochromatic images at approximately 63keV in dual-energy spectral CT pulmonary angiography yielded the best CNR and highest diagnostic confidence for imaging bronchial arteries. PMID:26967737

  2. 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.

  3. Coronary artery fistula (image)

    MedlinePlus

    A coronary artery fistula generally occurs when one of the coronary arteries fails to form properly during the development of the baby. Coronary artery fistula is an abnormal connection between one of ...

  4. Peripheral arterial line (image)

    MedlinePlus

    A peripheral arterial line is a small, short plastic catheter placed through the skin into an artery of the arm or leg. The purpose of a peripheral arterial line is to allow continuous monitoring of blood pressure ...

  5. Carotid artery anatomy (image)

    MedlinePlus

    There are four carotid arteries, two on each side of the neck: right and left internal carotid arteries, and right and left external carotid arteries. The carotid arteries deliver oxygen-rich blood from the heart to the head and brain.

  6. Coronary artery disease (image)

    MedlinePlus

    ... through these arteries is critical for the heart. Coronary artery disease usually results from the build-up of fatty material and plaque, a condition called atherosclerosis. As the ... blood to the heart can slow or stop, causing chest pain (stable ...

  7. 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.

  8. 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.

  9. Coronary Artery Imaging with Transthoracic Doppler Echocardiography.

    PubMed

    Takeuchi, Masaaki; Nakazono, Akemi

    2016-07-01

    Coronary artery imaging with transthoracic Doppler echocardiography is a simple and useful technique to diagnose significant coronary artery stenosis. The visualization of mosaic flow in the proximal left coronary artery provides a direct indication of the presence of significant stenosis at the corresponding site during routine echocardiography. Coronary flow velocity reserve (CFVR) has a high diagnostic accuracy and feasibility in detecting the presence of functionally significant coronary stenosis in the left anterior descending coronary artery (LAD) and in the right coronary artery. The measurement of CFVR in the LAD also provides prognostic information in patients with intermediate coronary stenosis. This review summarizes the utility of transthoracic coronary artery imaging. PMID:27216843

  10. Noninvasive Imaging in Coronary Artery Disease

    PubMed Central

    Heo, Ran; Nakazato, Ryo; Kalra, Dan; Min, James K.

    2014-01-01

    Noninvasive cardiac imaging is widely used to evaluate the presence of coronary artery disease. Recently, with improvements in imaging technology, noninvasive imaging has also been used for evaluation of the presence, severity, and prognosis of coronary artery disease. Coronary CT angiography and MRI of coronary arteries provide an anatomical assessment of coronary stenosis, whereas the hemodynamic significance of a coronary artery stenosis can be assessed by stress myocardial perfusion imaging, such as SPECT/PET and stress MRI. For appropriate use of multiple imaging modalities, the strengths and limitations of each modality are discussed in this review. PMID:25234083

  11. Coronary Artery Imaging in Children

    PubMed Central

    2015-01-01

    Coronary artery problems in children usually have a significant impact on both short-term and long-term outcomes. Early and accurate diagnosis, therefore, is crucial but technically challenging due to the small size of the coronary artery, high heart rates, and limited cooperation of children. Coronary artery visibility on CT and MRI in children is considerably improved with recent technical advancements. Consequently, CT and MRI are increasingly used for evaluating various congenital and acquired coronary artery abnormalities in children, such as coronary artery anomalies, aberrant coronary artery anatomy specific to congenital heart disease, Kawasaki disease, Williams syndrome, and cardiac allograft vasculopathy. PMID:25741188

  12. 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.

  13. Quality-aware images.

    PubMed

    Wang, Zhou; Wu, Guixing; Sheikh, Hamid Rahim; Simoncelli, Eero P; Yang, En-Hui; Bovik, Alan Conrad

    2006-06-01

    We propose the concept of quality-aware image, in which certain extracted features of the original (high-quality) image are embedded into the image data as invisible hidden messages. When a distorted version of such an image is received, users can decode the hidden messages and use them to provide an objective measure of the quality of the distorted image. To demonstrate the idea, we build a practical quality-aware image encoding, decoding and quality analysis system, which employs: 1) a novel reduced-reference image quality assessment algorithm based on a statistical model of natural images and 2) a previously developed quantization watermarking-based data hiding technique in the wavelet transform domain. PMID:16764291

  14. Imaging of a Cilioretinal Artery Embolisation

    PubMed Central

    Munk, Marion R.; Mirza, Rukhsana G.; Jampol, Lee M.

    2014-01-01

    Retinal artery occlusion can be the first indicator of a significant cardiovascular disorder and the need for treatment. We present the case of a 69-year-old man with a cilioretinal artery occlusion and retinal ischemia. Retinal imaging, in particular fundus autofluorescence, highlighted an intraluminal hyperautofluorescent lesion which led to the diagnosis of retinal emboli. Subsequently a severe, previously undiagnosed carotid occlusive disease was discovered. The patient underwent prompt endarterectomy. PMID:25192292

  15. 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

  16. 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

  17. Coronary artery imaging system using gated tomosynthesis

    SciTech Connect

    Macovski, A.

    1987-05-05

    A method is described of imaging a blood vessel such as a coronary artery. The steps comprise: providing radiation source means and radiation detector means on opposing sides of a target area and of administering a contrast agent intravenously; gating the radiation source means based on a selected time using an electrocardiogram to obtain detector signals indicative of views through the target area; and tomosynthesisly combining the detector signals to provide a planar image through the target area, the planar image being generally perpendicular to the path of radiation through the target area.

  18. Arterial spin labeling in clinical pediatric imaging.

    PubMed

    Proisy, M; Bruneau, B; Rozel, C; Trguier, C; Chouklati, K; Riffaud, L; Darnault, P; Ferr, J-C

    2016-02-01

    Arterial spin labeling (ASL) perfusion-weighted magnetic resonance imaging is the only approach that enables direct and non-invasive quantitative measurement of cerebral blood flow in the brain regions without administration of contrast material and without radiation. ASL is thus a promising perfusion imaging method for assessing cerebral blood flow in the pediatric population. Concerning newborns, there are current limitations because of their smaller brain size and lower brain perfusion. This article reviews and illustrates the use of ASL in pediatric clinical practice and discusses emerging cerebral perfusion imaging applications for children due to the highly convenient implementation of the ASL sequence. PMID:26456912

  19. MR Imaging of Coronary Arteries and Plaques.

    PubMed

    Dweck, Marc R; Puntman, Valentina; Vesey, Alex T; Fayad, Zahi A; Nagel, Eike

    2016-03-01

    Cardiac magnetic resonance offers the promise of radiation-free imaging of the coronary arteries, providing information with respect to luminal stenosis, plaque burden, high-risk plaque characteristics, and disease activity. In combination, this would provide a comprehensive, individualized assessment of coronary atherosclerosis that could be used to improve patient risk stratification and to guide treatment. However, the technical challenges involved with delivering upon this promise are considerable, requiring sophisticated approaches to both data acquisition and post-processing. In this review, we describe the current status of this technology, its capabilities, its limitations, and what will be required in the future to translate this technology into routine clinical practice. PMID:26965732

  20. Coronary artery remodeling in non-contrast CT images

    NASA Astrophysics Data System (ADS)

    Xu, Haiyong; Zheng, Mingna; Yang, Yanhua; Carr, J. Jeffery; Ge, Yaorong

    2012-03-01

    A significant cause of coronary artery disease is the coronary atherosclerosis which leads to stenosis of coronary arteries. It has been shown in recent studies, using intravascular ultrasound and contrast-enhanced CT, that early atherosclerosis causes positive coronary artery remodeling, defined as increases in the cross-sectional area. It is hypothesized that detection of artery remodeling using non-contrast CT can be an important factor in sub-clinical assessment of cardiac risk for asymptomatic subjects. However, measuring remodeling in coronary arteries in non-contrast CT images is a challenging task because coronary arteries are small and the intensity of coronary arteries is similar to that of surrounding tissues. Automatic segmentation algorithms that have been successful in segmenting coronary arteries in contrast-enhanced images do not perform well. To overcome these difficulties, we developed an interactive application to enable effective measurement of coronary artery remodeling in non-contrast CT images. This application is an extension to the 3D Slicer image analysis platform. It allows users to visualize and trace the centerline of arteries in cross sectional views. The artery centerlines are displayed in a three dimensional view overlaid on the original image volume and color-coded according to the artery labels. Using this 3D artery model, the user can sample the cross-sectional area of the arteries at selected points for remodeling assessment. Initial validation has demonstrated the effectiveness of this method. A pilot study also showed positive correlation of large coronary artery remodeling with highest lifetime risks. Further evaluation is underway using larger study size and more measurement points.

  1. Coronary artery balloon angioplasty - series (image)

    MedlinePlus

    ... and may eliminate the need for coronary artery bypass surgery. The outcome is relief from chest pain symptoms ... narrowing is not accomplished, heart surgery (coronary artery bypass graft surgery, also called a CABG) may be recommended.

  2. Segmentation of coronary arteries from CT angiography images

    NASA Astrophysics Data System (ADS)

    Fotin, Sergei V.; Reeves, Anthony P.; Cham, Matthew D.; Henschke, Claudia I.; Yankelevitz, David F.

    2007-03-01

    We present an automated method for delineation of coronary arteries from Cardiac CT Angiography (CTA) images. Coronary arteries are narrow blood vessels and when imaged using CTA, appear as thin cylindrical structures of varying curvature. This appearance is often affected by heart motion and image reconstruction artifacts. Moreover, when an artery is diseased, it may appear as a non-continuous structure of widely varying width and image intensity. Defining the boundaries of the coronary arteries is an important and necessary step for further analysis and diagnosis of coronary disease. For this purpose, we developed a method using cylindrical structure modeling. For each vessel segment a best fitting cylindrical template is found. By applying this technique sequentially along the vessel, its entire volume can be reconstructed. The algorithm is seeded with a manually specified starting point at the most distal discernible portion of an artery and then it proceeds iteratively toward the aorta. The algorithm makes necessary corrections to account for CTA image artifacts and is able to perform in diseased arteries. It stops when it identifies the vessels junction with the aorta. Five cardiac 3D CT angiography studies were used for algorithm validation. For each study, the four longest visually discernible branches of the major coronary arteries were evaluated. Central axes obtained from our automated method were compared with ground truth markings made by an experienced radiologist. In 75% of the cases, our algorithm was able to extract the entire length of the artery from single initialization.

  3. Carotid artery image segmentation using modified spatial fuzzy c-means and ensemble clustering.

    PubMed

    Hassan, Mehdi; Chaudhry, Asmatullah; Khan, Asifullah; Kim, Jin Young

    2012-12-01

    Disease diagnosis based on ultrasound imaging is popular because of its non-invasive nature. However, ultrasound imaging system produces low quality images due to the presence of spackle noise and wave interferences. This shortcoming requires a considerable effort from experts to diagnose a disease from the carotid artery ultrasound images. Image segmentation is one of the techniques, which can help efficiently in diagnosing a disease from the carotid artery ultrasound images. Most of the pixels in an image are highly correlated. Considering the spatial information of surrounding pixels in the process of image segmentation may further improve the results. When data is highly correlated, one pixel may belong to more than one clusters with different degree of membership. In this paper, we present an image segmentation technique namely improved spatial fuzzy c-means and an ensemble clustering approach for carotid artery ultrasound images to identify the presence of plaque. Spatial, wavelets and gray level co-occurrence matrix (GLCM) features are extracted from carotid artery ultrasound images. Redundant and less important features are removed from the features set using genetic search process. Finally, segmentation process is performed on optimal or reduced features. Ensemble clustering with reduced feature set outperforms with respect to segmentation time as well as clustering accuracy. Intima-media thickness (IMT) is measured from the images segmented by the proposed approach. Based on IMT measured values, Multi-Layer Back-Propagation Neural Networks (MLBPNN) is used to classify the images into normal or abnormal. Experimental results show the learning capability of MLBPNN classifier and validate the effectiveness of our proposed technique. The proposed approach of segmentation and classification of carotid artery ultrasound images seems to be very useful for detection of plaque in carotid artery. PMID:22981822

  4. 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

  5. Evaluation of image quality

    NASA Technical Reports Server (NTRS)

    Pavel, M.

    1993-01-01

    This presentation outlines in viewgraph format a general approach to the evaluation of display system quality for aviation applications. This approach is based on the assumption that it is possible to develop a model of the display which captures most of the significant properties of the display. The display characteristics should include spatial and temporal resolution, intensity quantizing effects, spatial sampling, delays, etc. The model must be sufficiently well specified to permit generation of stimuli that simulate the output of the display system. The first step in the evaluation of display quality is an analysis of the tasks to be performed using the display. Thus, for example, if a display is used by a pilot during a final approach, the aesthetic aspects of the display may be less relevant than its dynamic characteristics. The opposite task requirements may apply to imaging systems used for displaying navigation charts. Thus, display quality is defined with regard to one or more tasks. Given a set of relevant tasks, there are many ways to approach display evaluation. The range of evaluation approaches includes visual inspection, rapid evaluation, part-task simulation, and full mission simulation. The work described is focused on two complementary approaches to rapid evaluation. The first approach is based on a model of the human visual system. A model of the human visual system is used to predict the performance of the selected tasks. The model-based evaluation approach permits very rapid and inexpensive evaluation of various design decisions. The second rapid evaluation approach employs specifically designed critical tests that embody many important characteristics of actual tasks. These are used in situations where a validated model is not available. These rapid evaluation tests are being implemented in a workstation environment.

  6. 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

  7. Imaging lens design using image quality metric

    NASA Astrophysics Data System (ADS)

    Olives, Jean-Luc; Kolehmainen, Timo T.; Aikio, Janne; Kataja, Kari J.; Karioja, Pentti; Vuori, Tero; Mustonen, T.

    2004-02-01

    In the case of imaging optics for imaging cellular phones, special attention has to be paid on the cost of the lens system. The number of lens elements has to be minimized, but the image quality has to be maximized. It is important that optimum quality/cost - ratio is found. The image sensor characteristics and human visual system preferences have to be taken into consideration as well for the design. In this paper, we present our new image quality metric. The performance of the metric is investigated using subjective tests on different lens designs and compared with MTF metric. We show that our metric has a good correlation with human observer and performs better than MTF metric. Finally, we give some examples of optimization based on our metric.

  8. Image enhancement, image quality, and noise

    NASA Astrophysics Data System (ADS)

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

    2005-08-01

    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.

  9. 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.

  10. 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

  11. Branching patterns of the male internal iliac artery: imaging findings.

    PubMed

    Bilhim, Tiago; Casal, Diogo; Furtado, Andrea; Pais, Diogo; O'Neill, João Erse Goyri; Pisco, João Martins

    2011-03-01

    The aim of this study was to establish the imaging findings of the main branching patterns of the male internal iliac arteries, using different imaging modalities (angio MR, angio CT and digital angiography). Twenty-one males (mean age 73.2 years) underwent imaging evaluation with angio MR, angio CT and digital angiography to define the internal iliac artery anatomy before selective embolization of the pelvic arteries. All three modalities were used in 3 patients, angio MR and digital angiography in 17 patients, angio CT and digital angiography in 6 patients and only angio CT in 1 patient. Internal iliac arteries were classified into four groups using the Yamaki classification (modified from the Adachi's classification). Twenty-six pelvic sides were classified as Group A (61.9%), 13 as Group B (31%) and 3 as Group C (7.1%) with no cases of Group D found. Angio MR, angio CT and digital angiography were able to detect most branches of the internal iliac artery. Group A was the most frequent internal iliac artery branching pattern. Angio CT showed better detailed anatomy than angio MR and digital angiography was considered the gold-standard. Non-invasive vascular imaging with angio MR or angio CT is essential before invasive interventions, allowing better planning of the procedure. PMID:20798937

  12. Dynamic diffuse optical tomography imaging of peripheral arterial disease

    PubMed Central

    Khalil, Michael A.; Kim, Hyun K.; Kim, In-Kyong; Flexman, Molly; Dayal, Rajeev; Shrikhande, Gautam; Hielscher, Andreas H.

    2012-01-01

    Peripheral arterial disease (PAD) is the narrowing of arteries due to plaque accumulation in the vascular walls. This leads to insufficient blood supply to the extremities and can ultimately cause cell death. Currently available methods are ineffective in diagnosing PAD in patients with calcified arteries, such as those with diabetes. In this paper we investigate the potential of dynamic diffuse optical tomography (DDOT) as an alternative way to assess PAD in the lower extremities. DDOT is a non-invasive, non-ionizing imaging modality that uses near-infrared light to create spatio-temporal maps of oxy- and deoxy-hemoglobin in tissue. We present three case studies in which we used DDOT to visualize vascular perfusion of a healthy volunteer, a PAD patient and a diabetic PAD patient with calcified arteries. These preliminary results show significant differences in DDOT time-traces and images between all three cases, underscoring the potential of DDOT as a new diagnostic tool. PMID:23024920

  13. 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.

  14. Foveated wavelet image quality index

    NASA Astrophysics Data System (ADS)

    Wang, Zhou; Bovik, Alan C.; Lu, Ligang; Kouloheris, Jack L.

    2001-12-01

    The human visual system (HVS) is highly non-uniform in sampling, coding, processing and understanding. The spatial resolution of the HVS is highest around the point of fixation (foveation point) and decreases rapidly with increasing eccentricity. Currently, most image quality measurement methods are designed for uniform resolution images. These methods do not correlate well with the perceived foveated image quality. Wavelet analysis delivers a convenient way to simultaneously examine localized spatial as well as frequency information. We developed a new image quality metric called foveated wavelet image quality index (FWQI) in the wavelet transform domain. FWQI considers multiple factors of the HVS, including the spatial variance of the contrast sensitivity function, the spatial variance of the local visual cut-off frequency, the variance of human visual sensitivity in different wavelet subbands, and the influence of the viewing distance on the display resolution and the HVS features. FWQI can be employed for foveated region of interest (ROI) image coding and quality enhancement. We show its effectiveness by using it as a guide for optimal bit assignment of an embedded foveated image coding system. The coding system demonstrates very good coding performance and scalability in terms of foveated objective as well as subjective quality measurement.

  15. Global quality imaging: emerging issues.

    PubMed

    Lau, Lawrence S; Pérez, Maria R; Applegate, Kimberly E; Rehani, Madan M; Ringertz, Hans G; George, Robert

    2011-07-01

    Quality imaging may be described as "a timely access to and delivery of integrated and appropriate procedures, in a safe and responsive practice, and a prompt delivery of an accurately interpreted report by capable personnel in an efficient, effective, and sustainable manner." For this article, radiation safety is considered as one of the key quality elements. The stakeholders are the drivers of quality imaging. These include those that directly provide or use imaging procedures and others indirectly supporting the system. Imaging is indispensable in health care, and its use has greatly expanded worldwide. Globalization, consumer sophistication, communication and technological advances, corporatization, rationalization, service outsourcing, teleradiology, workflow modularization, and commoditization are reshaping practice. This article defines the emerging issues; an earlier article in the May 2011 issue described possible improvement actions. The issues that could threaten the quality use of imaging for all countries include workforce shortage; increased utilization, population radiation exposure, and cost; practice changes; and efficiency drive and budget constraints. In response to these issues, a range of quality improvement measures, strategies, and actions are used to maximize the benefits and minimize the risks. The 3 measures are procedure justification, optimization of image quality and radiation protection, and error prevention. The development and successful implementation of such improvement actions require leadership, collaboration, and the active participation of all stakeholders to achieve the best outcomes that we all advocate. PMID:21723489

  16. Multimodality Imaging in Coronary Artery Disease: Focus on Computed Tomography

    PubMed Central

    Lee, Ji Hyun; Han, Donghee; Danad, Ibrahim; Hartaigh, Bríain ó; Lin, Fay Y.

    2016-01-01

    Coronary artery disease (CAD) is the leading cause of mortality worldwide, and various cardiovascular imaging modalities have been introduced for the purpose of diagnosing and determining the severity of CAD. More recently, advances in computed tomography (CT) technology have contributed to the widespread clinical application of cardiac CT for accurate and noninvasive evaluation of CAD. In this review, we focus on imaging assessment of CAD based upon CT, which includes coronary artery calcium screening, coronary CT angiography, myocardial CT perfusion, and fractional flow reserve CT. Further, we provide a discussion regarding the potential implications, benefits and limitations, as well as the possible future directions according to each modality. PMID:27081438

  17. 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.

  18. 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

  19. [Stress imaging in coronary artery disease: state of the art].

    PubMed

    Baldini, U; Venturini, C; Genovesi-Ebert, A; Savoia, M T; Raugi, M; Pauletti, M; Carluccio, M; Digiorgio, A; Gasperetti, G; Galli, M

    2004-02-01

    To date, several diagnostic tools allow an accurate non-invasive evaluation of coronary artery disease; this is due to the great progress in echocardiographic and nuclear imaging techniques in the last 10 years. The large availability of different stress imaging techniques allows to choose the most appropriate technique for each patient according to the clinical characteristics. This paper presents the state of the art of echocardiographic and nuclear stress imaging for the diagnosis of coronary artery disease and for the prognostic stratification of infarcted patients. Advantages and limits of the different techniques are described rather than putting in competition echo and nuclear cardiology as has often been done in the past. Cardiologists should select among the various techniques on the basis of clinical characteristics of single patients, center's experience and an objective evaluation of economical aspects. PMID:14765034

  20. 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.

  1. The health-related quality of life of people with peripheral arterial disease in the community: the Edinburgh Artery Study

    PubMed Central

    Dumville, Jo C; Lee, Amanda J; Smith, Felicity B; Fowkes, F Gerald R

    2004-01-01

    Background: Previous studies investigating the health-related quality of life of those with peripheral arterial disease have focused on patients recruited from hospital clinics. The health-related quality of life of people with peripheral arterial disease in the general population is unknown. Aims: We aimed to determine the health-related quality of life of people with intermittent claudication and asymptomatic peripheral arterial disease in the general population and to compare it with those with angina and those with no peripheral arterial disease or angina. Design of study: Analysis of cross-sectional data from the 12-year follow-up of a population-based cohort. Setting: Edinburgh, Scotland. Method: Data from the Edinburgh Artery Study cohort's 12-year follow-up was analysed. Participants' peripheral arterial disease status was measured using the World Health Organisation intermittent claudication questionnaire and the ankle brachial pressure index. Self-assessed health-related quality of life data was collected using the SF-36 generic questionnaire. Health-related quality of life scores were calculated and their associations with peripheral arterial disease status groups were tested. Results: Subjects with intermittent claudication had significantly worse median health-related quality of life scores than patients without claudication in all domains except social functioning and mental health. Patients with claudication had a significantly lower physical component summary score than those without claudication (P≤0.001). This association remained after adjustment for age, sex, social class, body mass index, smoking, and angina. Those with angina and claudication had significantly worse physical component summary scores than those with no peripheral arterial disease or angina (P≤0.001). No significant difference was found in health-related quality of life scores between those with asymptomatic peripheral arterial disease and those with no peripheral arterial disease even after multiple adjustment for confounding factors. Conclusion: People with intermittent claudication in the community had impaired health-related quality of life related to reduced physical health, but asymptomatic peripheral arterial disease did not significantly affect health-related quality of life. PMID:15527608

  2. Improving quality and outcomes of coronary artery bypass grafting procedures.

    PubMed

    Ferguson, T Bruce; Buch, Ashesh N

    2016-05-01

    The evolution in the approach, clinical care and outcomes of ischemic heart disease, has been dramatic over the past decade. Optimizing medical therapy initially and throughout the care delivery process has been transformative. The addition of new physiologic data to the traditional anatomic framework for diagnosis and therapy of more extensive stable ischemic heart disease (SIHD) enables quality and outcomes improvements in this patient population overall and in the patient subsets of acute coronary syndrome and SIHD. In patients undergoing coronary artery bypass grafting (CABG), these developments have changed the objective goal of surgical revascularization over this time interval. This review discusses the opportunities for quality and outcomes improvement in CABG, in the context of SIHD overall. PMID:26818448

  3. Three-dimensional color Doppler imaging of the carotid artery

    NASA Astrophysics Data System (ADS)

    Picot, Paul A.; Rickey, Daniel W.; Mitchell, Ross; Rankin, Richard N.; Fenster, Aaron

    1991-05-01

    Stroke is the third leading cause of death in the United States. It is caused by ischemic injury to the brain, usually resulting from emboli from atherosclerotic plaques. The carotid bifurcation in humans is prone to atherosclerotic disease and is a site where emboli may originate. Currently, carotid stenoses are evaluated by non-invasive duplex Doppler ultrasound, with preoperative verification by intra-arterial angiography. We have developed a system that uses a color Doppler ultrasound imaging system to acquire in-vivo 3-D color Doppler images of the human carotid artery, with the aim of increasing the diagnostic accuracy of ultrasound and decreasing the use of angiography for verification. A clinical TL Ultramark 9 color Doppler ultrasound system was modified by mounting the hand-held ultrasound scan head on a motor-driven translation stage. The stage allows planar ultrasound images to be acquired over 45 mm along the neck between the clavicle and the mandible. A 3- D image is acquired by digitizing, in synchrony with the cardiac cycle, successive color ultrasound video images as the scan head is stepped along the neck. A complete volume set of 64 frames, comprising some 15 megabytes of data, requires approximately 2 minutes to acquire. The volume image is reformatted and displayed on a Sun 4/360 workstation equipped with a TAAC-1 graphics accelerator. The 3-D image may be manipulated in real time to yield the best view of blood flow in the bifurcation.

  4. Quality metrics for sensor images

    NASA Technical Reports Server (NTRS)

    Ahumada, AL

    1993-01-01

    Methods are needed for evaluating the quality of augmented visual displays (AVID). Computational quality metrics will help summarize, interpolate, and extrapolate the results of human performance tests with displays. The FLM Vision group at NASA Ames has been developing computational models of visual processing and using them to develop computational metrics for similar problems. For example, display modeling systems use metrics for comparing proposed displays, halftoning optimizing methods use metrics to evaluate the difference between the halftone and the original, and image compression methods minimize the predicted visibility of compression artifacts. The visual discrimination models take as input two arbitrary images A and B and compute an estimate of the probability that a human observer will report that A is different from B. If A is an image that one desires to display and B is the actual displayed image, such an estimate can be regarded as an image quality metric reflecting how well B approximates A. There are additional complexities associated with the problem of evaluating the quality of radar and IR enhanced displays for AVID tasks. One important problem is the question of whether intruding obstacles are detectable in such displays. Although the discrimination model can handle detection situations by making B the original image A plus the intrusion, this detection model makes the inappropriate assumption that the observer knows where the intrusion will be. Effects of signal uncertainty need to be added to our models. A pilot needs to make decisions rapidly. The models need to predict not just the probability of a correct decision, but the probability of a correct decision by the time the decision needs to be made. That is, the models need to predict latency as well as accuracy. Luce and Green have generated models for auditory detection latencies. Similar models are needed for visual detection. Most image quality models are designed for static imagery. Watson has been developing a general spatial-temporal vision model to optimize video compression techniques. These models need to be adapted and calibrated for AVID applications.

  5. High-definition imaging of carotid artery wall dynamics.

    PubMed

    Kruizinga, Pieter; Mastik, Frits; van den Oord, Stijn C H; Schinkel, Arend F L; Bosch, Johannes G; de Jong, Nico; van Soest, Gijs; van der Steen, Anton F W

    2014-10-01

    The carotid artery (CA) is central to cardiovascular research, because of the clinical relevance of CA plaques as culprits of stroke and the accessibility of the CA for cardiovascular screening. The viscoelastic state of this artery, essential for clinical evaluation, can be assessed by observing arterial deformation in response to the pressure changes throughout the cardiac cycle. Ultrasound imaging has proven to be an excellent tool to monitor these dynamic deformation processes. We describe how a new technique called high-frame-rate ultrasound imaging captures the tissue deformation dynamics throughout the cardiac cycle in unprecedented detail. Local tissue motion exhibits distinct features of sub-micrometer displacements on a sub-millisecond time scale. We present a high-definition motion analysis technique based on plane wave ultrasound imaging able to capture these features. We validated this method by screening a group of healthy volunteers and compared the results with those for two patients known to have atherosclerosis to illustrate the potential utility of this technique. PMID:25088760

  6. 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.

  7. Correlative magnetic resonance imaging in the evaluation of aortic and pulmonary artery abnormalities

    SciTech Connect

    Risius, B.; O'Donnell, J.K.; Geisinger, M.A.; Zelch, M.G.; George, C.R.; Graor, R.A.; Moodie, D.S.

    1985-05-01

    Magnetic resonance imaging (MRI) yields excellent quality images of the cardiovascular system utilizing the inherent natural contrast between flowing blood and the surrounding anatomic structures. To evaluate the clinical usefulness of MRI in the noninvasive diagnosis of large vessel disorders, the authors have performed MRI on 40 pts with either aortic or pulmonary artery abnormalities (18 thoracic or abdominal aortic aneurysms, 8 aorto-occlusive disease, 6 dissecting aneurysms, 4 Marfan's syndrome, 2 pulmonary artery aneurysms 1 pulmonary artery occlusion, 1 aortic coarctation). Images were obtained in the transverse, coronal and sagital body planes utilizing a 0.6T superconductive magnet. Cardiac and/or respiratory gating was employed in most cases. Correlation was made for all studies with conventional or digital subtraction angiography, computed tomography, and/or ultrasound. The diagnostic information obtained by MRI equaled or exceeded that obtained by other imaging techniques except for the few cases where cardiac arrhythmias precluded adequate gated acquisition. All aneurysms and their relationships to adjacent structures were readily demonstrated as were the presence or absence of mural thrombi and dissecting intimal flaps. Angiographically demonstrated atherosclerotic plaques and luminal stenoses were seen by MRI in all patients without arrhythmias. The authors concluded that MRI is a powerful noninvasive diagnostic aid in the delineation of large vessel disorders, especially where knowledge of anatomic interrelationships can guide surgical or other interventional planning.

  8. Noncontrast-enhanced peripheral MRA: technical optimization of flow-spoiled fresh blood imaging for screening peripheral arterial diseases.

    PubMed

    Nakamura, Katsumi; Miyazaki, Mitsue; Kuroki, Kiyomi; Yamamoto, Akiyoshi; Hiramine, Akihiro; Admiraal-Behloul, Faiza

    2011-02-01

    Flow-spoiled fresh blood imaging, a noncontrast peripheral MR angiography technique, allows the depiction of the entire tree of peripheral arteries by utilizing the signal difference between systolic- and diastolic-triggered data. The image quality of the technique relies on selecting the right triggering delay times and flow-dependent read-out spoiler gradient pulses. ECG triggering delays were verified using manual subtraction and automated software. The read-out spoiler gradients pulses were optimized on volunteers before utilizing the flow-spoiled fresh blood imaging technique to screen for peripheral arterial disease. Thirteen consecutive patients with suspected peripheral arterial disease underwent both flow-spoiled fresh blood imaging and 16-detector-row computed tomography angiography examinations. A total of 23 segments were evaluated in the arterial vascular system. Using computed tomography angiography as the reference standard, 56 diseased segments were detected with 22 nonsignificant stenoses (<50%) and 34 significant stenoses, 15 of which were totally occluded. Flow-spoiled fresh blood imaging had a sensitivity of 97%, a specificity of 96%, an accuracy of 96%, a positive predictive value of 88%, and a negative predictive value of 99%. With such a high negative predictive value, flow-spoiled fresh blood imaging has the potential to become the safest noninvasive screening tool for peripheral arterial disease, especially for patients with impaired renal function. PMID:20872867

  9. Variation in electrosurgical vessel seal quality along the length of a porcine carotid artery.

    PubMed

    Wyatt, Hayley Louise; Richards, Rosie; Pullin, Rhys; Yang, Th Jimmy; Blain, Emma J; Evans, Sam L

    2016-03-01

    Electrosurgical vessel sealing has been demonstrated to have benefits for both patients and practitioners, but significant variation in the strength of the seal continues to be a concern. This study aims to examine the variation in electrosurgical seal quality along the length of a porcine common carotid artery and explore the relationships between seal quality, vessel size and morphology. Additionally, the study aimed to investigate the minimum safety threshold for successful seals and the influence of vessel characteristics on meeting this requirement. A total of 35 porcine carotid arteries were sealed using the PlasmaKinetic Open Seal device (Gyrus). Each seal was burst pressure tested and a sample taken for staining with elastin van Gieson's stain, with morphological quantification using image processing software ImageJ. With increasing distance from the bifurcation, there was an increase in seal strength and a reduction in both elastin content and vessel outer diameter. A significant correlation was found between burst pressure with both outer diameter (p < 0.0001) and elastin content (p = 0.001). When considering the safe limits of operation, vessels of less than 5 mm in outer diameter were shown to consistently produce a seal of a sufficient strength (burst pressure > 360 mmHg) irrespective of vessel morphology. PMID:26743899

  10. Variation in electrosurgical vessel seal quality along the length of a porcine carotid artery

    PubMed Central

    Wyatt, Hayley Louise; Richards, Rosie; Pullin, Rhys; Yang, TH Jimmy; Blain, Emma J; Evans, Sam L

    2016-01-01

    Electrosurgical vessel sealing has been demonstrated to have benefits for both patients and practitioners, but significant variation in the strength of the seal continues to be a concern. This study aims to examine the variation in electrosurgical seal quality along the length of a porcine common carotid artery and explore the relationships between seal quality, vessel size and morphology. Additionally, the study aimed to investigate the minimum safety threshold for successful seals and the influence of vessel characteristics on meeting this requirement. A total of 35 porcine carotid arteries were sealed using the PlasmaKinetic Open Seal device (Gyrus). Each seal was burst pressure tested and a sample taken for staining with elastin van Gieson’s stain, with morphological quantification using image processing software ImageJ. With increasing distance from the bifurcation, there was an increase in seal strength and a reduction in both elastin content and vessel outer diameter. A significant correlation was found between burst pressure with both outer diameter (p < 0.0001) and elastin content (p = 0.001). When considering the safe limits of operation, vessels of less than 5 mm in outer diameter were shown to consistently produce a seal of a sufficient strength (burst pressure > 360 mmHg) irrespective of vessel morphology. PMID:26743899

  11. Noncontrast MR Angiography for Comprehensive Assessment of Abdominopelvic Arteries using Quadruple Inversion-Recovery Preconditioning and 3D balanced Steady-State Free Precession Imaging

    PubMed Central

    Atanasova, Iliyana P.; Kim, Daniel; Lim, Ruth P.; Storey, Pippa; Kim, Sooah; Guo, Hua; Lee, Vivian S.

    2011-01-01

    Purpose To develop a non-contrast MR angiography (MRA) method for comprehensive evaluation of abdominopelvic arteries in a single 3D acquisition. Materials and Methods A non-contrast MRA (NC MRA) pulse sequence was developed using 4 inversion-recovery (IR) pulses and 3D balanced steady-state free precession (b-SSFP) readout to provide arterial imaging from renal to external iliac arteries. Respiratory triggered, high spatial resolution (1.3 × 1.3 × 1.7 mm3) non-contrast angiograms were obtained in seven volunteers and ten patients referred for gadolinium-enhanced MRA (CE MRA). Images were assessed for diagnostic quality by two radiologists. Quantitative measurements of arterial signal contrast were also performed. Results NC MRA imaging was successfully completed in all subjects in 7.0 ± 2.3 minutes. In controls, image quality of NC MRA averaged 2.79 ± 0.39 on a scale of 0 to 3, where 3 is maximum. Image quality of NC MRA (2.65 ± 0.41) was comparable to that of CE MRA (2.9 ± 0.32) in all patients. Contrast ratio measurements in patients demonstrated that NC MRA provides arterial contrast comparable to source CE MRA images with adequate venous and excellent background tissue suppression. Conclusion The proposed non-contrast MRA pulse sequence provides high quality visualization of abdominopelvic arteries within clinically feasible scan times. PMID:21591013

  12. Despeckle filtering software toolbox for ultrasound imaging of the common carotid artery.

    PubMed

    Loizou, Christos P; Theofanous, Charoula; Pantziaris, Marios; Kasparis, Takis

    2014-04-01

    Ultrasound imaging of the common carotid artery (CCA) is a non-invasive tool used in medicine to assess the severity of atherosclerosis and monitor its progression through time. It is also used in border detection and texture characterization of the atherosclerotic carotid plaque in the CCA, the identification and measurement of the intima-media thickness (IMT) and the lumen diameter that all are very important in the assessment of cardiovascular disease (CVD). Visual perception, however, is hindered by speckle, a multiplicative noise, that degrades the quality of ultrasound B-mode imaging. Noise reduction is therefore essential for improving the visual observation quality or as a pre-processing step for further automated analysis, such as image segmentation of the IMT and the atherosclerotic carotid plaque in ultrasound images. In order to facilitate this preprocessing step, we have developed in MATLAB(®) a unified toolbox that integrates image despeckle filtering (IDF), texture analysis and image quality evaluation techniques to automate the pre-processing and complement the disease evaluation in ultrasound CCA images. The proposed software, is based on a graphical user interface (GUI) and incorporates image normalization, 10 different despeckle filtering techniques (DsFlsmv, DsFwiener, DsFlsminsc, DsFkuwahara, DsFgf, DsFmedian, DsFhmedian, DsFad, DsFnldif, DsFsrad), image intensity normalization, 65 texture features, 15 quantitative image quality metrics and objective image quality evaluation. The software is publicly available in an executable form, which can be downloaded from http://www.cs.ucy.ac.cy/medinfo/. It was validated on 100 ultrasound images of the CCA, by comparing its results with quantitative visual analysis performed by a medical expert. It was observed that the despeckle filters DsFlsmv, and DsFhmedian improved image quality perception (based on the expert's assessment and the image texture and quality metrics). It is anticipated that the system could help the physician in the assessment of cardiovascular image analysis. PMID:24560276

  13. Arterial Tortuosity Syndrome: An Approach through Imaging Perspective.

    PubMed

    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

  14. Automatic determination of the artery vein ratio in retinal images

    NASA Astrophysics Data System (ADS)

    Niemeijer, Meindert; van Ginneken, Bram; Abràmoff, Michael D.

    2010-03-01

    A lower ratio between the width of the arteries and veins (Arteriolar-to-Venular diameter Ratio, AVR) on the retina, is well established to be predictive of stroke and other cardiovascular events in adults, as well as an increased risk of retinopathy of prematurity in premature infants. This work presents an automatic method that detects the location of the optic disc, determines the appropriate region of interest (ROI), classifies the vessels in the ROI into arteries and veins, measures their widths and calculates the AVR. After vessel segmentation and vessel width determination the optic disc is located and the system eliminates all vessels outside the AVR measurement ROI. The remaining vessels are thinned, vessel crossing and bifurcation points are removed leaving a set of vessel segments containing centerline pixels. Features are extracted from each centerline pixel that are used to assign them a soft label indicating the likelihood the pixel is part of a vein. As all centerline pixels in a connected segment should be the same type, the median soft label is assigned to each centerline pixel in the segment. Next artery vein pairs are matched using an iterative algorithm and the widths of the vessels is used to calculate the AVR. We train and test the algorithm using a set of 25 high resolution digital color fundus photographs a reference standard that indicates for the major vessels in the images whether they are an artery or a vein. We compared the AVR values produced by our system with those determined using a computer assisted method in 15 high resolution digital color fundus photographs and obtained a correlation coefficient of 0.881.

  15. Objective Quality Assessment of Interpolated Natural Images.

    PubMed

    Yeganeh, Hojatollah; Rostami, Mohammad; Wang, Zhou

    2015-11-01

    Image interpolation techniques that create high-resolution images from low-resolution (LR) images are widely used in real world applications, but how to evaluate the quality of interpolated images is not a well-resolved issue. Subjective assessment methods are useful and reliable, but are also slow and expensive. Here, we propose an objective method to assess the quality of an interpolated natural image using the available LR image as a reference. Our method adopts a natural scene statistics (NSS) framework, where image quality degradation is gauged by the deviation of its statistical features from the NSS models trained upon high-quality natural images. Two distortion measures are proposed, namely, interpolated natural image distortion (IND) and weighted IND. Validations by subjective tests show that the proposed approach performs statistically equivalent or sometimes better than an average human subject. Moreover, we demonstrate the potential application of the proposed method in parameter tuning of image interpolation algorithms. PMID:26186792

  16. Infrared image quality evaluation method without reference image

    NASA Astrophysics Data System (ADS)

    Yue, Song; Ren, Tingting; Wang, Chengsheng; Lei, Bo; Zhang, Zhijie

    2013-09-01

    Since infrared image quality depends on many factors such as optical performance and electrical noise of thermal imager, image quality evaluation becomes an important issue which can conduce to both image processing afterward and capability improving of thermal imager. There are two ways of infrared image quality evaluation, with or without reference image. For real-time thermal image, the method without reference image is preferred because it is difficult to get a standard image. Although there are various kinds of methods for evaluation, there is no general metric for image quality evaluation. This paper introduces a novel method to evaluate infrared image without reference image from five aspects: noise, clarity, information volume and levels, information in frequency domain and the capability of automatic target recognition. Generally, the basic image quality is obtained from the first four aspects, and the quality of target is acquired from the last aspect. The proposed method is tested on several infrared images captured by different thermal imagers. Calculate the indicators and compare with human vision results. The evaluation shows that this method successfully describes the characteristics of infrared image and the result is consistent with human vision system.

  17. 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.

  18. 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.

  19. Direct Characterization of Arterial Input Functions by Fluorescence Imaging of Exposed Carotid Artery to Facilitate Kinetic Analysis

    PubMed Central

    Elliott, Jonathan T.; Tichauer, Kenneth M.; Samkoe, Kimberley S.; Gunn, Jason R.; Sexton, Kristian J.; Pogue, Brian W.

    2014-01-01

    Purpose With the goal of facilitating tracer kinetic analysis in small-animal planar fluorescence imaging, an experimental method for characterizing tracer arterial input functions is presented. The proposed method involves exposing the common carotid arteries by surgical dissection, which can then be imaged directly during tracer injection and clearance. Procedures Arterial concentration curves of IRDye-700DX-carboxylate, IRDye-800CW-EGF, and IRDye-800CW conjugated to anti-EGFR Affibody are recovered from athymic female mice (n=12) by directly imaging exposed vessels. Images were acquired with two imaging protocols: a slow-kinetics approach (temporal resolution=45 s) to recover the arterial curves from two tracers simultaneously, and a fast-kinetics approach (temporal resolution=500 ms) to characterize the first-pass peak of a single tracer. Arterial input functions obtained by the carotid imaging technique, as well as plasma curves measured by blood sampling were fit with a biexponential pharmacokinetic model. Results Pharmacological fast- and slow-phase rate constants recovered with the proposed method were 0.37±0.26 and 0.007±0.001 min−1, respectively, for the IRDye700DX-C. For the IRDye800CW-EGF, the rate constants were 0.11±0.13 and 0.003±0.002 min−1. These rate constants did not differ significantly from those calculated previously by blood sampling, as determined by an F test; however, the between-subject variability was four times lower for arterial curves recovered using the proposed technique, compared with blood sampling. Conclusions The proposed technique enables the direct characterization of arterial input functions for kinetic analysis. As this method requires no additional instrumentation, it is immediately deployable in commercially available planar fluorescence imaging systems. PMID:24420443

  20. Coronary artery anomalies in adults: imaging at dual source CT coronary angiography.

    PubMed

    Laspas, Fotios; Roussakis, Arkadios; Mourmouris, Christos; Kritikos, Nikolaos; Efthimiadou, Roxani; Andreou, John

    2013-04-01

    Congenital abnormalities of the coronary arteries have an incidence of 1%, and most of these are benign. However, a small number are associated with myocardial ischaemia and sudden death. Various imaging modalities are available for coronary artery assessment. Recently, multi-detector CT has emerged as an accurate diagnostic tool for defining coronary artery anomalies. The purpose of this pictorial essay is to review the dual source CT appearance of congenital anomalies of the coronary arteries in adults. PMID:23551776

  1. An Underwater Color Image Quality Evaluation Metric.

    PubMed

    Yang, Miao; Sowmya, Arcot

    2015-12-01

    Quality evaluation of underwater images is a key goal of underwater video image retrieval and intelligent processing. To date, no metric has been proposed for underwater color image quality evaluation (UCIQE). The special absorption and scattering characteristics of the water medium do not allow direct application of natural color image quality metrics especially to different underwater environments. In this paper, subjective testing for underwater image quality has been organized. The statistical distribution of the underwater image pixels in the CIELab color space related to subjective evaluation indicates the sharpness and colorful factors correlate well with subjective image quality perception. Based on these, a new UCIQE metric, which is a linear combination of chroma, saturation, and contrast, is proposed to quantify the non-uniform color cast, blurring, and low-contrast that characterize underwater engineering and monitoring images. Experiments are conducted to illustrate the performance of the proposed UCIQE metric and its capability to measure the underwater image enhancement results. They show that the proposed metric has comparable performance to the leading natural color image quality metrics and the underwater grayscale image quality metrics available in the literature, and can predict with higher accuracy the relative amount of degradation with similar image content in underwater environments. Importantly, UCIQE is a simple and fast solution for real-time underwater video processing. The effectiveness of the presented measure is also demonstrated by subjective evaluation. The results show better correlation between the UCIQE and the subjective mean opinion score. PMID:26513783

  2. Automatic active contour-based segmentation and classification of carotid artery ultrasound images.

    PubMed

    Chaudhry, Asmatullah; Hassan, Mehdi; Khan, Asifullah; Kim, Jin Young

    2013-12-01

    In this paper, we present automatic image segmentation and classification technique for carotid artery ultrasound images based on active contour approach. For early detection of the plaque in carotid artery to avoid serious brain strokes, active contour-based techniques have been applied successfully to segment out the carotid artery ultrasound images. Further, ultrasound images might be affected due to rotation, scaling, or translational factors during acquisition process. Keeping in view these facts, image alignment is used as a preprocessing step to align the carotid artery ultrasound images. In our experimental study, we exploit intima-media thickness (IMT) measurement to detect the presence of plaque in the artery. Support vector machine (SVM) classification is employed using these segmented images to distinguish the normal and diseased artery images. IMT measurement is used to form the feature vector. Our proposed approach segments the carotid artery images in an automatic way and further classifies them using SVM. Experimental results show the learning capability of SVM classifier and validate the usefulness of our proposed approach. Further, the proposed approach needs minimum interaction from a user for an early detection of plaque in carotid artery. Regarding the usefulness of the proposed approach in healthcare, it can be effectively used in remote areas as a preliminary clinical step even in the absence of highly skilled radiologists. PMID:23417308

  3. New quality metrics for digital image resizing

    NASA Astrophysics Data System (ADS)

    Kim, Hongseok; Kumara, Soundar

    2007-09-01

    Digital image rescaling by interpolation has been intensively researched over past decades, and still getting constant attention from many applications such as medical diagnosis, super-resolution, image blow-up, nano-manufacturing, etc. However, there are no consented metrics to objectively assess and compare the quality of resized images. Some existing measures such as peak-signal-to-noise ratio (PSNR) or mean-squared error (MSE), widely used in image restoration area, do not always coincide with the opinions from viewers. Enlarged digital images generally suffer from two major artifacts: blurring, zigzagging, and those undesirable effects especially around edges significantly degrade the overall perceptual image quality. We propose two new image quality metrics to measure the degree of the two major defects, and compare several existing interpolation methods using the proposed metrics. We also evaluate the validity of image quality metrics by comparing rank correlations.

  4. Process perspective on image quality evaluation

    NASA Astrophysics Data System (ADS)

    Leisti, Tuomas; Halonen, Raisa; Kokkonen, Anna; Weckman, Hanna; Mettänen, Marja; Lensu, Lasse; Ritala, Risto; Oittinen, Pirkko; Nyman, Göte

    2008-01-01

    The psychological complexity of multivariate image quality evaluation makes it difficult to develop general image quality metrics. Quality evaluation includes several mental processes and ignoring these processes and the use of a few test images can lead to biased results. By using a qualitative/quantitative (Interpretation Based Quality, IBQ) methodology, we examined the process of pair-wise comparison in a setting, where the quality of the images printed by laser printer on different paper grades was evaluated. Test image consisted of a picture of a table covered with several objects. Three other images were also used, photographs of a woman, cityscape and countryside. In addition to the pair-wise comparisons, observers (N=10) were interviewed about the subjective quality attributes they used in making their quality decisions. An examination of the individual pair-wise comparisons revealed serious inconsistencies in observers' evaluations on the test image content, but not on other contexts. The qualitative analysis showed that this inconsistency was due to the observers' focus of attention. The lack of easily recognizable context in the test image may have contributed to this inconsistency. To obtain reliable knowledge of the effect of image context or attention on subjective image quality, a qualitative methodology is needed.

  5. 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 μm 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.

  6. JPEG2000 still image coding quality.

    PubMed

    Chen, Tzong-Jer; Lin, Sheng-Chieh; Lin, You-Chen; Cheng, Ren-Gui; Lin, Li-Hui; Wu, Wei

    2013-10-01

    This work demonstrates the image qualities between two popular JPEG2000 programs. Two medical image compression algorithms are both coded using JPEG2000, but they are different regarding the interface, convenience, speed of computation, and their characteristic options influenced by the encoder, quantization, tiling, etc. The differences in image quality and compression ratio are also affected by the modality and compression algorithm implementation. Do they provide the same quality? The qualities of compressed medical images from two image compression programs named Apollo and JJ2000 were evaluated extensively using objective metrics. These algorithms were applied to three medical image modalities at various compression ratios ranging from 10:1 to 100:1. Following that, the quality of the reconstructed images was evaluated using five objective metrics. The Spearman rank correlation coefficients were measured under every metric in the two programs. We found that JJ2000 and Apollo exhibited indistinguishable image quality for all images evaluated using the above five metrics (r > 0.98, p < 0.001). It can be concluded that the image quality of the JJ2000 and Apollo algorithms is statistically equivalent for medical image compression. PMID:23589187

  7. 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

  8. Automated construction of arterial and venous trees in retinal images.

    PubMed

    Hu, Qiao; Abràmoff, Michael D; Garvin, Mona K

    2015-10-01

    While many approaches exist to segment retinal vessels in fundus photographs, only a limited number focus on the construction and disambiguation of arterial and venous trees. Previous approaches are local and/or greedy in nature, making them susceptible to errors or limiting their applicability to large vessels. We propose a more global framework to generate arteriovenous trees in retinal images, given a vessel segmentation. In particular, our approach consists of three stages. The first stage is to generate an overconnected vessel network, named the vessel potential connectivity map (VPCM), consisting of vessel segments and the potential connectivity between them. The second stage is to disambiguate the VPCM into multiple anatomical trees, using a graph-based metaheuristic algorithm. The third stage is to classify these trees into arterial or venous (A/V) trees. We evaluated our approach with a ground truth built based on a public database, showing a pixel-wise classification accuracy of 88.15% using a manual vessel segmentation as input, and 86.11% using an automatic vessel segmentation as input. PMID:26636114

  9. 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.

  10. 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.

  11. Stereoscopic image quality metrics and compression

    NASA Astrophysics Data System (ADS)

    Gorley, Paul; Holliman, Nick

    2008-02-01

    We are interested in metrics for automatically predicting the compression settings for stereoscopic images so that we can minimize file size, but still maintain an acceptable level of image quality. Initially we investigate how Peak Signal to Noise Ratio (PSNR) measures the quality of varyingly coded stereoscopic image pairs. Our results suggest that symmetric, as opposed to asymmetric stereo image compression, will produce significantly better results. However, PSNR measures of image quality are widely criticized for correlating poorly with perceived visual quality. We therefore consider computational models of the Human Visual System (HVS) and describe the design and implementation of a new stereoscopic image quality metric. This, point matches regions of high spatial frequency between the left and right views of the stereo pair and accounts for HVS sensitivity to contrast and luminance changes at regions of high spatial frequency, using Michelson's Formula and Peli's Band Limited Contrast Algorithm. To establish a baseline for comparing our new metric with PSNR we ran a trial measuring stereoscopic image encoding quality with human subjects, using the Double Stimulus Continuous Quality Scale (DSCQS) from the ITU-R BT.500-11 recommendation. The results suggest that our new metric is a better predictor of human image quality preference than PSNR and could be used to predict a threshold compression level for stereoscopic image pairs.

  12. Multimodality image fusion for diagnosing coronary artery disease

    PubMed Central

    Piccinelli, Marina; Garcia, Ernest

    2013-01-01

    Coronary artery disease (CAD) is one of the leading causes of death in the US and a substantial health-care burden in all industrialized societies. In recent years we have witnessed a constant strive towards the development and the clinical application of novel or improved detection methods as well as therapies. Particularly, noninvasive imaging is a decisive component in the cardiovascular field. Image fusion is the ability of combining into a single integrated display the anatomical as well as the physiological data retrieved by separated modalities. Clinical evidence suggests that it represents a promising strategy in CAD assessment and risk stratification by significantly improving the diagnostic power of each modality independently considered and of the traditional side-by-side interpretation. Numerous techniques and approaches taken from the image registration field have been implemented and validated in the context of CAD assessment and management. Although its diagnostic power is widely accepted, additional technical developments are still needed to become a routinely used clinical tool. PMID:24285942

  13. Daily Marital Interaction Quality and Carotid Artery Intima Medial Thickness in Healthy Middle Aged Adults

    PubMed Central

    Joseph, Nataria T.; Kamarck, Thomas W.; Muldoon, Matthew F.; Manuck, Stephen B.

    2014-01-01

    Objective To examine the association between marital interaction quality during daily life and subclinical cardiovascular disease (CVD). Studies have shown that marital status and quality of marriage are associated with cardiovascular health. However, little is known about the role of marital interaction quality during daily life in contributing to these effects. Methods The sample consisted of 281 healthy, employed middle-aged adults who were married or living with a partner in a marital-like relationship (mean age = 42.0 years, 88% white, 52% men). Marital interaction quality was assessed using hourly real-time Ecological Momentary Assessments (EMAs) for 4 days, with participants rating their current or recent partner interactions on positive and negative characteristics (e.g., agreeableness and conflict). Carotid artery intima medial thickness (IMT) was assessed using ultrasound imaging. Results Adjusting for demographics, positive marital interaction was inversely associated with IMT, [b = −.02 F(1, 275) = 9.18, p = .002], and negative marital interaction was positively associated with IMT, [b = .02 F(1, 275) = 10.29, p = .001]. These associations were not accounted for by behavioral and biological cardiovascular disease (CVD) risk factors and were consistent across age, sex, race, and education. The associations were also independent of marital interaction frequency, nonmarital social interaction quality, and personality factors. Global reports of marital quality, in contrast, were not associated with IMT. Conclusions Marital quality as measured during real-time interactions between partners was associated with subclinical cardiovascular disease in healthy middle-aged adults. This study supports the utility of real-time social interaction assessment for characterizing links between social relationships and cardiovascular health. PMID:24915293

  14. Retinal image quality assessment using generic features

    NASA Astrophysics Data System (ADS)

    Fasih, Mahnaz; Langlois, J. M. Pierre; Ben Tahar, Houssem; Cheriet, Farida

    2014-03-01

    Retinal image quality assessment is an important step in automated eye disease diagnosis. Diagnosis accuracy is highly dependent on the quality of retinal images, because poor image quality might prevent the observation of significant eye features and disease manifestations. A robust algorithm is therefore required in order to evaluate the quality of images in a large database. We developed an algorithm for retinal image quality assessment based on generic features that is independent from segmentation methods. It exploits the local sharpness and texture features by applying the cumulative probability of blur detection metric and run-length encoding algorithm, respectively. The quality features are combined to evaluate the image's suitability for diagnosis purposes. Based on the recommendations of medical experts and our experience, we compared a global and a local approach. A support vector machine with radial basis functions was used as a nonlinear classifier in order to classify images to gradable and ungradable groups. We applied our methodology to 65 images of size 2592×1944 pixels that had been graded by a medical expert. The expert evaluated 38 images as gradable and 27 as ungradable. The results indicate very good agreement between the proposed algorithm's predictions and the medical expert's judgment: the sensitivity and specificity for the local approach are respectively 92% and 94%. The algorithm demonstrates sufficient robustness to identify relevant images for automated diagnosis.

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

    PubMed Central

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

    2015-01-01

    Abstract. 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

  16. 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.

  17. 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

  18. Paediatric cerebrovascular CT angiography—towards better image quality

    PubMed Central

    Thust, Stefanie C.; Chong, Wui Khean Kling; Gunny, Roxana; Mazumder, Asif; Poitelea, Marius; Welsh, Anna; Ederies, Ash

    2014-01-01

    Background Paediatric cerebrovascular CT angiography (CTA) can be challenging to perform due to variable cardiovascular physiology between different age groups and the risk of movement artefact. This analysis aimed to determine what proportion of CTA at our institution was of diagnostic quality and identify technical factors which could be improved. Materials and methods a retrospective analysis of 20 cases was performed at a national paediatric neurovascular centre assessing image quality with a subjective scoring system and Hounsfield Unit (HU) measurements. Demographic data, contrast dose, flow rate and triggering times were recorded for each patient. Results Using a qualitative scoring system, 75% of studies were found to be of diagnostic quality (n=9 ‘good’, n=6 ‘satisfactory’) and 25% (n=5) were ‘poor’. Those judged subjectively to be poor had arterial contrast density measured at less than 250 HU. Increased arterial opacification was achieved for cases performed with an increased flow rate (2.5-4 mL/s) and higher intravenous contrast dose (2 mL/kg). Triggering was found to be well timed in nine cases, early in four cases and late in seven cases. Of the scans triggered early, 75% were poor. Of the scans triggered late, less (29%) were poor. Conclusions High flow rates (>2.5 mL/s) were a key factor for achieving high quality paediatric cerebrovascular CTA imaging. However, appropriate triggering by starting the scan immediately on contrast opacification of the monitoring vessel plays an important role and could maintain image quality when flow rates were lower. Early triggering appeared more detrimental than late. PMID:25525579

  19. Analysis of SAR images quality degradation factors

    NASA Astrophysics Data System (ADS)

    Dawidowicz, Bartek; Samczynski, Piotr; Smolarczyk, Maciej; Kuzmiuk, Marek

    2006-03-01

    Quality of Synthetic Aperture Radar (SAR) images is very sensitive for both pulse signal spectrum purity and stability of the radar platform flight path. In this paper detailed influence of this factors on SAR images quality is analyzed. Analysis is based mainly on computer simulations. This kind of analysis is very important because not all SAR image degradation factors can be compensated using digital signal processing algorithms.

  20. Thallium-201 myocardial imaging in young adults with anomalous left coronary artery arising from the pulmonary artery

    SciTech Connect

    Moodie, D.S.; Cook, S.A.; Gill, C.C.; Napoli, C.A.

    1980-11-01

    Anomalous origin of the left coronary artery from the pulmonary artery (Bland-Garland-White syndrome) may produce myocardial ischemia, infarction, and frequently death in infancy. Some patients, however, develop satisfactory coronary artery collaterals and are relatively asymptomatic into adulthood. Very little is known about their myocardial perfusion patterns. We studied three young adults with this condition using stress thallium-201 myocardial imaging. Electrocardiograms in two patients demonstrated old arterolateral myocardial infarctions. Preoperative stress exercise tests were positive in all three patients. Marked perfusion abnormalities were found in the proximal anterolateral wall in all patients, and one patient also had a posterolateral defect. Postoperatively, all stress tests returned to normal. Thallium imaging demonstrated improvement in ischemic areas, but old scars persisted.

  1. A new image quality assessment database for tiled images

    NASA Astrophysics Data System (ADS)

    McFadden, Steven B.; Ward, Paul A. S.

    2014-01-01

    Tiled displays fill the increasingly important need to display very large images. As these displays become more common, the ability to objectively measure their visual quality becomes more important. One cost of the size flexibility offered by these displays is the grid-type distortion created by the gaps between each sub-display's active area. General purpose Image Quality Assessment (IQA) metrics are commonly used to measure the visual quality effect of image distortions such as blur and white noise, but no research has been performed to determine their suitability for tiling distortions. This paper addresses that research gap by creating a new image quality database specifically targeting tiled images. Common state-of-the-art IQA metrics are tested against this new database and their performances are compared between tiled distortions and `traditional' image distortions.

  2. Quantitative perfusion mapping with arterial spin labeling magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Keilholz-George, Shella Dawn

    2001-12-01

    Quantitative, noninvasive perfusion images are desirable for the evaluation of blood flow. To date, most quantitative perfusion maps have been obtained with nuclear scintigraphy, which suffers from low spatial resolution and requires a radioactive tracer. A class of magnetic resonance imaging (MRI) techniques, pulsed arterial spin labeling (ASL), can be used to obtain perfusion-weighted MR images that are completely noninvasive and have high spatial and temporal resolution. Quantitative images are more difficult to obtain with this technique, since additional images and post-processing are required. In this study, the utility of pulsed ASL for quantitative perfusion imaging was examined, the two commonly used methods of quantitation (referred to as the FAIR and T1 methods) were described, and a new method (the mole fraction method) that requires fewer images and less processing, making it more feasible for clinical applications, was introduced. Perfusion maps of the kidneys in healthy volunteers were calculated pixel by pixel and the results were compared to those obtained with the FAIR and T1 methods. The average perfusion rates were 387 +/- 54 ml/100g/min for the FAIR method, and 385 +/- 54 ml/100g/min and 433 +/- 83 ml/100g/min for two variants of the mole fraction method. ASL techniques employ inversion recovery and/or saturation recovery to induce perfusion weighting, and thus the performance of these techniques is dependent upon the slice profiles of the inversion or saturation pulses. The effects of slice profile imperfections on the perfusion signal were systematically examined through simulations for nine labeling schemes. Each sequence is evaluated for quantitative accuracy, suppression of stationary signal, and magnitude of perfusion signal. Perfusion effects are modeled from a modified Bloch equation and experimentally determined slice profiles. The results show that the three most common ASL sequences have excellent tissue suppression and comparable perfusion signal. For quantitative measurements, all three methods underestimate the perfusion signal by more than 20%. Of the additional six ASL techniques examined, only one performed well in this model. This method, which combines inversion and saturation recovery, yields improved signal accuracy (<15% difference from the theoretical value) and tissue suppression similar to that of the first three, but has only half the signal.

  3. 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.

  4. High-Pitch CT Pulmonary Angiography in Third Generation Dual-Source CT: Image Quality in an Unselected Patient Population

    PubMed Central

    Sabel, Bastian O.; Buric, Kristijan; Karara, Nora; Thierfelder, Kolja M.; Dinkel, Julien; Sommer, Wieland H.; Meinel, Felix G.

    2016-01-01

    Objectives To investigate the feasibility of high-pitch CT pulmonary angiography (CTPA) in 3rd generation dual-source CT (DSCT) in unselected patients. Methods Forty-seven patients with suspected pulmonary embolism underwent high-pitch CTPA on a 3rd generation dual-source CT scanner. CT dose index (CTDIvol) and dose length product (DLP) were obtained. Objective image quality was analyzed by calculating signal-to-noise-ratio (SNR) and contrast-to-noise ratio (CNR). Subjective image quality on the central, lobar, segmental and subsegmental level was rated by two experienced radiologists. Results Median CTDI was 8.1 mGy and median DLP was 274 mGy*cm. Median SNR was 32.9 in the central and 31.9 in the segmental pulmonary arteries. CNR was 29.2 in the central and 28.2 in the segmental pulmonary arteries. Median image quality was “excellent” in central and lobar arteries and “good” in subsegmental arteries according to both readers. Segmental arteries varied between “excellent” and “good”. Image quality was non-diagnostic in one case (2%), beginning in the lobar arteries. Thirteen patients (28%) showed minor motion artifacts. Conclusions In third-generation dual-source CT, high-pitch CTPA is feasible for unselected patients. It yields excellent image quality with minimal motion artifacts. However, compared to standard-pitch cohorts, no distinct decrease in radiation dose was observed. PMID:26872262

  5. 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.

  6. Impact of SAR image quality on recognition

    NASA Astrophysics Data System (ADS)

    Carlson, Daniel W.; Montagnino, Lee J.; Frankot, Robert T.

    2005-05-01

    Automatic target recognition (ATR) performance is a function of image quality and its representation in the signature model generation and used in the ATR training process. This paper reports ATR performance as a function of synthetic aperture radar (SAR) image quality parameters including clutter-to-noise ratio (CNR) and multiplicative noise ratio (MNR). Images with specified image quality values were produced by introducing controlled degradations to the MSTAR public release data. Two different families of ATR algorithms, the statistical model-based classifier of DeVore, et al., and optimal tradeoff synthetic discriminant function (OTSDF) are applied to those data. Target classification accuracy was measured as a function of CNR/MNR for both the training and test data, indicating sensitivity of performance to a priori knowledge of these particular image quality parameters. Confusion matrices are expanded to include target aspect bins, providing visibility into performance as a function of aspect angle.

  7. 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.

    2015-09-01

    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.

  8. [Effect of hypoestrogenemia on quality of life of premenopausal women with arterial hypertension].

    PubMed

    Khabibulina, M M

    2013-01-01

    Quality of life (QL) of premenopausal women (n = 76) with arterial hypertension (AH) with normal and low level of estradiol was studied with the use of Short Form 36 Health Quality Survey. QL of women with estrogen deficit was significantly worse than QL of premenopausal female patients with preserved estrogen level. PMID:24654434

  9. 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.

  10. Exercise thallium-201 myocardial imaging in left main coronary artery disease: sensitive but not specific

    SciTech Connect

    Rehn, T.; Griffith, L.S.; Achuff, S.C.; Bailey, I.K.; Bulkley, B.H.; Burow, R.; Pitt, B.; Becker, L.C.

    1981-08-01

    To determine the usefulness of thallium-201 scintigraphy for identifying left main coronary artery disease, the results of scintigraphy at rest and during exercise were compared in 24 patients with 50 percent or greater narrowing of the left main coronary artery and 80 patients with 50 percent or greater narrowing of one or more of the major coronary arteries but without left main coronary involvement. By segmental analysis of the scintigrams, perfusion defects were assigned to the left anterior descending, left circumflex or right coronary artery, singly or in combination, and the pattern of simultaneous left anterior descending and circumflex arterial defects was used to identify left main coronary artery disease. Of the 24 patients with left main coronary artery disease, 22 (92 percent) had abnormal exercise scintigrams. Despite this high sensitivity, the pattern of perfusion defects was not specific; the ''left main pattern'' was found in 3 patients (13 percent) with left main coronary artery disease but also in 3 (33 percent) of 9 patients with combined left anterior descending and left circumflex arterial disease, 4 (19 percent) of 21 patients with three vessel disease and 3 (6 percent) of 50 patients with one or two vessel disease but excluding the group with left anterior descending plus left circumflex arterial disease. The pattern of perfusion defects in the patients with left main coronary artery disease was determined by the location and severity of narrowings in the coronary arteries downstream from the left main arterial lesion. Concomitant lesions in other arteries were found in all patients with left main coronary disease (one vessel in 1 patient, two vessels in 7 patients and three vessels in 16). For this reason, it is unlikely that even with improvements in radiopharmaceutical agents and imaging techniques, myocardial perfusion scintigraphy will be sufficiently specific for definitive identification of left main coronary artery disease.

  11. Quantification of pulmonary arterial wall distensibility using parameters extracted from volumetric micro-CT images

    NASA Astrophysics Data System (ADS)

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

    1999-09-01

    Stiffening, or loss of distensibility, of arterial vessel walls is among the manifestations of a number of vascular diseases including pulmonary arterial hypertension. We are attempting to quantify the mechanical properties of vessel walls of the pulmonary arterial tree using parameters derived from high-resolution volumetric x-ray CT images of rat lungs. The pulmonary arterial trees of the excised lungs are filled with a contrast agent. The lungs are imaged with arterial pressures spanning the physiological range. Vessel segment diameters are measured from the inlet to the periphery, and distensibilities calculated from diameters as a function of pressure. The method shows promise as an adjunct to other morphometric techniques such as histology and corrosion casting. It possesses the advantages of being nondestructive, characterizing the vascular structures while the lungs are imaged rapidly and in a near-physiological state, and providing the ability to associate mechanical properties with vessel location in the intact tree hierarchy.

  12. Two- and three-dimensional quantitative image analysis of coronary arteries from high-resolution histological sections

    NASA Astrophysics Data System (ADS)

    Holmes, David R., III; Robb, Richard A.

    2000-05-01

    The study of coronary arteries has evolved from examining gross anatomy and morphology to scrutinizing micro-anatomy and cellular composition. Technological advances such as high-powered digital microscopes and high precision cutting devices have allowed clinicians to examine coronary artery morphology and pathology at micron resolution. Our work explores the composition of normal coronary arteries in order to provide the foundation for further study of remodeled tissue. The first of two coronary arteries was sliced into 442 sections with 4 micron inter-slice spacing. Each slice was stained for elastin and collagen. The second coronary artery was sectioned into 283 slices, also with 4 micron resolution. These slices were stained for cellular nuclei and smooth muscle. High sectioned into 283 slices, also with 4 micron resolution. These slices were stained for cellular nuclei and smooth muscle. High resolution light microscopy was used to image the sections. The data was analyzed for collagen/elastin content and nuclei density, respectively. Processing of this type of data is challenging in the areas of segmentation, visualization and quantification. Segmentation was confounded by variation in image quality as well as complexity of the coronary tissue. These problems were overcome by the development of 'smart' thresholding algorithms for segmentation. In addition, morphology and image statistics were used to further refine the result of the segmentation. Specificity/sensitivity analysis suggests that automatic segmentation can be very effective. 3D visualization of coronary arteries is challenging due to multiple tissue layers. Method such as summed voxel projection and maximum intensity projection appear to be effective. Shading methods also provide adequate visualization, however it is important to incorporate combined 2D and 3D displays. Surface rendering techniques are useful tools for visualizing parametric data. Quantification in 3D is simple in practice but appropriate descriptions of these results must be displayed to clinicians in a clear way. Preliminary results are promising, but continued development of algorithms for processing histological data is needed.

  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. In vivo imaging of superficial femoral artery (SFA) stents for deformation analysis

    NASA Astrophysics Data System (ADS)

    Ganguly, A.; Schneider, A.; Keck, B.; Bennett, N. R.; Fahrig, R.

    2008-03-01

    A high-resolution (198 μm) C-arm CT imaging system (Axiom Artis dTA, Siemens Medical Solutions, Forchheim, Germany) was optimized for imaging superficial femoral artery (SFA) stents in humans. The SFA is susceptible to the development of atherosclerotic lesions. These are typically treated with angioplasty and stent deployment. However, these stents can have a fracture rate as high as 35%. Fracture is usually accompanied by restenosis and reocclusion. The exact cause of breakage is unknown and is hypothesized to result from deforming forces due to hip and knee flexion. Imaging was performed with the leg placed in both straight and bent positions. Projection images obtained during 20 s scans with ~200° of rotation of the C-arm were back-projected to obtain 3D volumes. Using a semi-automatic software algorithm developed in-house, the stent centerlines were found and ellipses were fitted to the slice normals. Image quality was adequate for calculations in 11/13 subjects. Bending the leg was found to shorten the stents in 10/11 cases with the maximum change being 9% (12 mm in a 133 mm stent), and extend the stent in one case by 1.6%. The maximum eccentricity change was 36% with a bend angle of 72° in a case where the stent extended behind the knee.

  15. Toward clinically relevant standardization of image quality.

    PubMed

    Samei, Ehsan; Rowberg, Alan; Avraham, Ellie; Cornelius, Craig

    2004-12-01

    In recent years, notable progress has been made on standardization of medical image presentations in the definition and implementation of the Digital Imaging and Communications in Medicine (DICOM) Grayscale Standard Display Function (GSDF). In parallel, the American Association of Physicists in Medicine (AAPM) Task Group 18 has provided much needed guidelines and tools for visual and quantitative assessment of medical display quality. In spite of these advances, however, there are still notable gaps in the effectiveness of DICOM GSDF to assure consistent and high-quality display of medical images. In additions the degree of correlation between display technical data and diagnostic usability and performance of displays remains unclear. This article proposes three specific steps that DICOM, AAPM, and ACR may collectively take to bridge the gap between technical performance and clinical use: (1) DICOM does not provide means and acceptance criteria to evaluate the conformance of a display device to GSDF or to address other image quality characteristics. DICOM can expand beyond luminance response, extending the measurable, quantifiable elements of TG18 such as reflection and resolution. (2) In a large picture archiving and communication system (PACS) installation, it is critical to continually track the appropriate use and performance of multiple display devices. DICOM may help with this task by adding a Device Service Class to the standard to provide for communication and control of image quality parameters between applications and devices, (3) The question of clinical significance of image quality metrics has rarely been addressed by prior efforts. In cooperation with AAPM, the American College of Radiology (ACR), and the Society for Computer Applications in Radiology (SCAR), DICOM may help to initiate research that will determine the clinical consequence of variations in image quality metrics (eg, GSDF conformance) and to define what constitutes image quality from a diagnostic perspective. Implementation of these three initiatives may further the reach and impact of DICOM toward quality medicine. PMID:15551103

  16. Image quality evaluation using moving targets

    NASA Astrophysics Data System (ADS)

    Artmann, Uwe

    2013-03-01

    The basic concept of testing a digital imaging device is to reproduce a known target and to analyze the resulting image. This semi-reference approach can be used for various different aspects of image quality. Each part of the imaging chain can have an influence on the results: lens, sensor, image processing and the target itself. The results are valid only for the complete system. If we want to test a single component, we have to make sure that we change only one and keep all others constant. When testing mobile imaging devices, we run into the problem that hardly anything can be manually controlled by the tester. Manual exposure control is not available for most devices, the focus cannot be influenced and hardly any settings for the image processing are available. Due to the limitations in the hardware, the image pipeline in the digital signal processor (DSP) of mobile imaging devices is a critical part of the image quality evaluation. The processing power of the DSPs allows sharpening, tonal correction and noise reduction to be non-linear and adaptive. This makes it very hard to describe the behavior for an objective image quality evaluation. The image quality is highly influenced by the signal processing for noise and resolution and the processing is the main reason for the loss of low contrast, _ne details, the so called texture blur. We present our experience to describe the image processing in more detail. All standardized test methods use a defined chart and require, that the chart and the camera are not moved in any way during test. In this paper, we present our results investigating the influence of chart movement during the test. Different structures, optimized for different aspects of image quality evaluation, are moved with a defined speed during the capturing process. The chart movement will change the input for the signal processing depending on the speed of the target during the test. The basic theoretical changes in the image will be the introduction of motion blur. With the known speed and the measured exposure time, we can calculate the theoretical motion blur. We compare the theoretical influence of the motion blur with the measured results. We use different methods to evaluate image quality parameter vs. motion speed of the chart. Slanted edges are used to obtain a SFR and to check for image sharpening. The aspect of texture blur is measured using dead leaves structures. The theoretical and measured results are plotted against the speed of the chart and allow an insight into the behavior of the DSP.

  17. Tradeoffs between image quality and dose.

    PubMed

    Seibert, J Anthony

    2004-10-01

    Image quality takes on different perspectives and meanings when associated with the concept of as low as reasonably achievable (ALARA), which is chiefly focused on radiation dose delivered as a result of a medical imaging procedure. ALARA is important because of the increased radiosensitivity of children to ionizing radiation and the desire to keep the radiation dose low. By the same token, however, image quality is also important because of the need to provide the necessary information in a radiograph in order to make an accurate diagnosis. Thus, there are tradeoffs to be considered between image quality and radiation dose, which is the main topic of this article. ALARA does not necessarily mean the lowest radiation dose, nor, when implemented, does it result in the least desirable radiographic images. With the recent widespread implementation of digital radiographic detectors and displays, a new level of flexibility and complexity confronts the technologist, physicist, and radiologist in optimizing the pediatric radiography exam. This is due to the separation of the acquisition, display, and archiving events that were previously combined by the screen-film detector, which allows for compensation for under- and overexposures, image processing, and on-line image manipulation. As explained in the article, different concepts must be introduced for a better understanding of the tradeoffs encountered when dealing with digital radiography and ALARA. In addition, there are many instances during the image acquisition/display/interpretation process in which image quality and associated dose can be compromised. This requires continuous diligence to quality control and feedback mechanisms to verify that the goals of image quality, dose and ALARA are achieved. PMID:15558260

  18. 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.

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

    NASA Astrophysics Data System (ADS)

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

    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.

  20. Quality of Life after Intra-arterial Therapy for Acute Ischemic Stroke

    PubMed Central

    Cortez, Melissa M.; Wilder, Michael; McFadden, Molly; Majersik, Jennifer J.

    2014-01-01

    Few data exist about health-related quality of life outcomes after intra-arterial therapy for acute ischemic stroke. We assessed stroke-specific quality of life in stroke survivors after intra-arterial therapy. Consecutive patients undergoing intra-arterial therapy for acute ischemic stroke from 2005-2010 were retrospectively identified via an institutional database. Stroke-specific quality of life (using the Stroke-Specific Quality of Life Score) and disability status (modified Rankin Scale) were prospectively assessed via mailed questionnaire. We analyzed quality of life scores by domain and summary score, with a summary score of ≥ 4 defined as a good outcome. Analysis of variance was used to model the effect of final recanalization status, stroke severity, and modified Rankin Scale on total quality of life score. ANOVA and Pearson's correlations were used to test the association between stroke severity/modified Rankin Scale and quality of life/time since stroke respectively. Of ninety-nine acute ischemic stroke patients, 61 responded yielding: 11 interim deaths, 7 incomplete surveys, and 43 complete surveys for analysis. Among responding survivors, overall quality of life score was 3.9 (SD 0.7); 77% of these reported good quality of life. Scores were higher in recanalized patients in 11 of 12 domains, but was significant only for mood. Although modified Rankin Scale was associated with stroke severity, quality of life was independent of both. Seventy-seven percent of acute ischemic stroke survivors who received intra-arterial therapy reported good quality of life. Furthermore, these data suggest that stroke-specific quality of life is an independent outcome from stroke severity and disability status. PMID:24813258

  1. Pitfalls of Doppler Measurements for Arterial Blood Flow Quantification in Small Animal Research: A Study Based on Virtual Ultrasound Imaging.

    PubMed

    Swillens, Abigail; Shcherbakova, Darya; Trachet, Bram; Segers, Patrick

    2016-06-01

    High-resolution Doppler is a popular tool for evaluating cardiovascular physiology in mutant mice, though its 1-D nature and spectral broadening processes complicate interpretation of the measurement. Hence, it is crucial for pre-clinical researchers to know how error sources in Doppler assessments reveal themselves in the murine arterial system. Therefore, we performed virtual Doppler experiments in a computer model of an aneurysmatic murine aorta with full control of the imaging and insonified fluid dynamics. We observed significant variability in Doppler performance and derived vascular indices depending on the interrogated flow, operator settings and signal processing. In particular, we found that (i) Doppler spectra in the upper aortic branches and celiac artery exhibited more broadening because of complex out-of-beam flow paths; (ii) mean frequency tracking outperforms tracking of the outer envelope, but is sensitive to errors in angle correction; and (iii) imaging depths deviating much from the elevation focus suffer from decreased spectral quality. PMID:27004960

  2. Implementation of quantitative perfusion imaging using pulsed arterial spin labeling at ultra-high field.

    PubMed

    Gardener, A G; Gowland, P A; Francis, S T

    2009-04-01

    This study compares the implementation of the STAR and FAIR pulsed arterial spin labeling (PASL) schemes to form quantitative perfusion maps at ultra-high field, 7 Tesla (T), and high field, 3 T. Phantom experiments were performed to compare the inversion efficiency and profile of the labeling pulses at 7 T and 3 T and to optimize in-plane saturation techniques. The perfusion weighted (PW) signal was measured at a range of postlabeling delay times and quantitative perfusion maps were calculated on a voxel-by-voxel basis. An increase in PW signal was found with field strength, and together with the increased signal-to-noise ratio, this led to improved image signal-to-noise and quality of fit of perfusion maps at 7 T. PMID:19189295

  3. 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.

  4. Laser-induced fluorescence imaging of coronary arteries for open-heart surgery applications

    NASA Astrophysics Data System (ADS)

    Taylor, Roderick S.; Gladysz, D.; Brown, Derek W.; Higginson, Lyall A. J.

    1991-07-01

    A technique utilizing laser induced fluorescence has been developed to obtain direct real-time imaging of the coronary artery network for open heart surgery applications. Both excimer pumped dye and cw argon-ion laser radiation transmitted through a fused silica fiber were used as laser sources to irradiate swine, bovine, and human cadaver hearts whose coronary arteries had been injected with strongly fluorescent dyes. The laser induces fluorescence originating from within the coronary arteries and detected by the surgeon's eye, allows the entire coronary network to be directly viewed. A comparison between laser induced fluorescence and the use of direct visual inspection of arteries following injection of the dye Cardio-Green(R) as well as conventional thermal imaging is presented. The limitations imposed on each technique by layers of fat on top of the coronary arteries are also described. The possibility of using these techniques to detect mechanical or laser beam perforations during laser endarterectomy procedures is discussed.

  5. Robust carotid artery recognition in longitudinal B-mode ultrasound images.

    PubMed

    Sifakis, Emmanouil G; Golemati, Spyretta

    2014-09-01

    Automatic segmentation of the arterial lumen from ultrasound images is an important task in clinical diagnosis. Carotid artery recognition, the first task in lumen segmentation, should be performed in a fully automated, fast, and reliable way to further facilitate the low-level task of arterial delineation. In this paper, a user-independent, real-time algorithm is introduced for carotid artery localization in longitudinal B-mode ultrasound images. The proposed technique acts directly on the raw image, and exploits basic statistics along with anatomical knowledge. The method's evaluation and parameter value optimization were performed on a threefold cross validation basis. In addition, the introduced algorithm was systematically compared with another algorithm for common carotid artery recognition in B-mode scans, separately for multi-frame and single-frame data. The data sets used included 2,149 images from 100 subjects taken from three different institutions and covering a wide range of possible lumen and surrounding tissue representations. Using the optimized values, the carotid artery was recognized in all the processed images in both multi-frame and single-frame data. Thus, the introduced technique will further reinforce automatic segmentation in longitudinal B-mode ultrasound images. PMID:24968172

  6. Color image processing for date quality evaluation

    NASA Astrophysics Data System (ADS)

    Lee, Dah Jye; Archibald, James K.

    2010-01-01

    Many agricultural non-contact visual inspection applications use color image processing techniques because color is often a good indicator of product quality. Color evaluation is an essential step in the processing and inventory control of fruits and vegetables that directly affects profitability. Most color spaces such as RGB and HSV represent colors with three-dimensional data, which makes using color image processing a challenging task. Since most agricultural applications only require analysis on a predefined set or range of colors, mapping these relevant colors to a small number of indexes allows simple and efficient color image processing for quality evaluation. This paper presents a simple but efficient color mapping and image processing technique that is designed specifically for real-time quality evaluation of Medjool dates. In contrast with more complex color image processing techniques, the proposed color mapping method makes it easy for a human operator to specify and adjust color-preference settings for different color groups representing distinct quality levels. Using this color mapping technique, the color image is first converted to a color map that has one color index represents a color value for each pixel. Fruit maturity level is evaluated based on these color indices. A skin lamination threshold is then determined based on the fruit surface characteristics. This adaptive threshold is used to detect delaminated fruit skin and hence determine the fruit quality. The performance of this robust color grading technique has been used for real-time Medjool date grading.

  7. Image quality for large segmented space telescopes

    NASA Astrophysics Data System (ADS)

    Lightsey, Paul A.; Chrisp, Michael

    2003-03-01

    Some proposed architectures for large telescopes in space such as the Next Generation Space Telescope (NGST) utilize a segmented primary mirror with active control. The image quality for those systems can be characterized by the quality of the point spread function (PSF). We will present results from our simulations that demonstrate the quality of the PSF at various wavelengths, as characterized by the metrics of Strehl Ratio and encircled energy fraction. These metrics capture the critical features of the PSF that ensure good spatial resolution of the core at the nominal diffraction limited wavelength without having excessive scattering into the nearby diffraction pattern for observations at shorter wavelengths. The relationship of the image quality to the spatial frequency content of the system wave front error and to the image motion that occurs during the exposure (line-of-sight jitter) are explored.

  8. 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.

  9. Measurement and control of color image quality

    NASA Astrophysics Data System (ADS)

    Schneider, Eric; Johnson, Kate; Wolin, David

    1998-12-01

    Color hardcopy output is subject to many of the same image quality concerns as monochrome hardcopy output. Line and dot quality, uniformity, halftone quality, the presence of bands, spots or deletions are just a few by both color and monochrome output. Although measurement of color requires the use of specialized instrumentation, the techniques used to assess color-dependent image quality attributes on color hardcopy output are based on many of the same techniques as those used in monochrome image quality quantification. In this paper we will be presenting several different aspects of color quality assessment in both R and D and production environments. As well as present several examples of color quality measurements that are similar to those currently being used at Hewlett-Packard to characterize color devices and to verify system performance. We will then discuss some important considerations for choosing appropriate color quality measurement equipment for use in either R and D or production environments. Finally, we will discuss the critical relationship between objective measurements and human perception.

  10. Simultaneous automatic arteries-veins separation and cerebral blood flow imaging with single-wavelength laser speckle imaging.

    PubMed

    Feng, Nengyun; Qiu, Jianjun; Li, Pengcheng; Sun, Xiaoli; Yin, Cui; Luo, Weihua; Chen, Shangbin; Luo, Qingming

    2011-08-15

    Automatic separation of arteries and veins in optical cerebral cortex images is important in clinical practice and preclinical study. In this paper, a simple but effective automatic artery-vein separation method which utilizes single-wavelength coherent illumination is presented. This method is based on the relative temporal minimum reflectance analysis of laser speckle images. The validation is demonstrated with both theoretic simulations and experimental results applied to the rat cortex. Moreover, this method can be combined with laser speckle contrast analysis so that the artery-vein separation and blood flow imaging can be simultaneously obtained using the same raw laser speckle images data to enable more accurate analysis of changes of cerebral blood flow within different tissue compartments during functional activation, disease dynamic, and neurosurgery, which may broaden the applications of laser speckle imaging in biology and medicine. PMID:21934940

  11. Simultaneous automatic arteries-veins separation and cerebral blood flow imaging with single-wavelength laser speckle imaging

    NASA Astrophysics Data System (ADS)

    Feng, Nengyun; Qiu, Jianjun; Li, Pengcheng; Sun, Xiaoli; Yin, Cui; Luo, Weihua; Chen, Shangbin; Luo, Qingming

    2011-08-01

    Automatic separation of arteries and veins in optical cerebral cortex images is important in clinical practice and preclinical study. In this paper, a simple but effective automatic artery-vein separation method which utilizes single-wavelength coherent illumination is presented. This method is based on the relative temporal minimum reflectance analysis of laser speckle images. The validation is demonstrated with both theoretic simulations and experimental results applied to the rat cortex. Moreover, this method can be combined with laser speckle contrast analysis so that the artery-vein separation and blood flow imaging can be simultaneously obtained using the same raw laser speckle images data to enable more accurate analysis of changes of cerebral blood flow within different tissue compartments during functional activation, disease dynamic, and neurosurgery, which may broaden the applications of laser speckle imaging in biology and medicine.

  12. MR and CT imaging of the structural and functional changes of pulmonary arterial hypertension

    PubMed Central

    Schiebler, Mark L.; Bhalla, Sanjeev; Runo, James; Jarjour, Nizar; Roldan, Alejandro; Chesler, Naomi; François, Christopher J.

    2013-01-01

    The current Dana Point classification system (2009) divides elevation of pulmonary artery pressure into Pulmonary Arterial Hypertension (PAH) and Pulmonary Hypertension (PH). Fortunately, pulmonary arterial hypertension (PAH) is not a common disease. However, with the aging of the first world’s population, heart failure is now an important cause of pulmonary hypertension with up to 9% of the population involved. PAH is usually asymptomatic until late in the disease process. While there are indirect features of PAH found on noninvasive imaging studies, the diagnosis and management still requires right heart catheterization. Imaging features of PAH include: 1. Enlargement of the pulmonary trunk and main pulmonary arteries, 2. Decreased pulmonary arterial compliance, 3. Tapering of the peripheral pulmonary arteries, 4. Enlargement of the inferior vena cava, and 5. Increased mean transit time. The chronic requirement to generate high pulmonary arterial pressures measurably affects the right heart and main pulmonary artery. This change in physiology causes the following structural and functional alterations that have been shown to have prognostic significance: Relative area change of the pulmonary trunk, RVSVindex, RVSV, RVEDVindex, LVEDVindex, and baseline RVEF <35%. All of these variables can be quantified non-invasively and followed longitudinally in each patient using MRI to modify the treatment regimen. Untreated PAH frequently results in a rapid clinical decline and death within 3 years of diagnosis. Unfortunately, even with treatment, less than 1/2 of these patients are alive at four years. PMID:23612440

  13. 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.

  14. 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.

  15. Automated characterization of blood vessels as arteries and veins in retinal images.

    PubMed

    Mirsharif, Qazaleh; Tajeripour, Farshad; Pourreza, Hamidreza

    2013-01-01

    In recent years researchers have found that alternations in arterial or venular tree of the retinal vasculature are associated with several public health problems such as diabetic retinopathy which is also the leading cause of blindness in the world. A prerequisite for automated assessment of subtle changes in arteries and veins, is to accurately separate those vessels from each other. This is a difficult task due to high similarity between arteries and veins in addition to variation of color and non-uniform illumination inter and intra retinal images. In this paper a novel structural and automated method is presented for artery/vein classification of blood vessels in retinal images. The proposed method consists of three main steps. In the first step, several image enhancement techniques are employed to improve the images. Then a specific feature extraction process is applied to separate major arteries from veins. Indeed, vessels are divided to smaller segments and feature extraction and vessel classification are applied to each small vessel segment instead of each vessel point. Finally, a post processing step is added to improve the results obtained from the previous step using structural characteristics of the retinal vascular network. In the last stage, vessel features at intersection and bifurcation points are processed for detection of arterial and venular sub trees. Ultimately vessel labels are revised by publishing the dominant label through each identified connected tree of arteries or veins. Evaluation of the proposed approach against two different datasets of retinal images including DRIVE database demonstrates the good performance and robustness of the method. The proposed method may be used for determination of arteriolar to venular diameter ratio in retinal images. Also the proposed method potentially allows for further investigation of labels of thinner arteries and veins which might be found by tracing them back to the major vessels. PMID:23849699

  16. Blind image quality assessment through anisotropy.

    PubMed

    Gabarda, Salvador; Cristóbal, Gabriel

    2007-12-01

    We describe an innovative methodology for determining the quality of digital images. The method is based on measuring the variance of the expected entropy of a given image upon a set of predefined directions. Entropy can be calculated on a local basis by using a spatial/spatial-frequency distribution as an approximation for a probability density function. The generalized Rényi entropy and the normalized pseudo-Wigner distribution (PWD) have been selected for this purpose. As a consequence, a pixel-by-pixel entropy value can be calculated, and therefore entropy histograms can be generated as well. The variance of the expected entropy is measured as a function of the directionality, and it has been taken as an anisotropy indicator. For this purpose, directional selectivity can be attained by using an oriented 1-D PWD implementation. Our main purpose is to show how such an anisotropy measure can be used as a metric to assess both the fidelity and quality of images. Experimental results show that an index such as this presents some desirable features that resemble those from an ideal image quality function, constituting a suitable quality index for natural images. Namely, in-focus, noise-free natural images have shown a maximum of this metric in comparison with other degraded, blurred, or noisy versions. This result provides a way of identifying in-focus, noise-free images from other degraded versions, allowing an automatic and nonreference classification of images according to their relative quality. It is also shown that the new measure is well correlated with classical reference metrics such as the peak signal-to-noise ratio. PMID:18059913

  17. Registration of coronary arteries in computed tomography angiography images using Hidden Markov Model.

    PubMed

    Luo, Yuxuan; Feng, Jianjiang; Xu, Miao; Zhou, Jie; Min, James K; Xiong, Guanglei

    2015-08-01

    Computed tomography angiography (CTA) allows for not only diagnosis of coronary artery disease (CAD) with high spatial resolution but also monitoring the remodeling of vessel walls in the progression of CAD. Alignment of coronary arteries in CTA images acquired at different times (with a 3-7 years interval) is required to visualize and analyze the geometric and structural changes quantitatively. Previous work in image registration primarily focused on large anatomical structures and leads to suboptimal results when applying to registration of coronary arteries. In this paper, we develop a novel method to directly align the straightened coronary arteries in the cylindrical coordinate system guided by the extracted centerlines. By using a Hidden Markov Model (HMM), image intensity information from CTA and geometric information of extracted coronary arteries are combined to align coronary arteries. After registration, the pathological features in two straightened coronary arteries can be directly visualized side by side by synchronizing the corresponding cross-sectional slices and circumferential rotation angles. By evaluating with manually labeled landmarks, the average distance error is 1.6 mm. PMID:26736676

  18. Registration of Coronary Arteries in Computed Tomography Angiography Images using Hidden Markov Model

    PubMed Central

    Luo, Yuxuan; Feng, Jianjiang; Xu, Miao; Zhou, Jie; Min, James K.; Xiong, Guanglei

    2016-01-01

    Computed tomography angiography (CTA) allows for not only diagnosis of coronary artery disease (CAD) with high spatial resolution but also monitoring the remodeling of vessel walls in the progression of CAD. Alignment of coronary arteries in CTA images acquired at different times (with a 3–7 years interval) is required to visualize and analyze the geometric and structural changes quantitatively. Previous work in image registration primarily focused on large anatomical structures and leads to suboptimal results when applying to registration of coronary arteries. In this paper, we develop a novel method to directly align the straightened coronary arteries in the cylindrical coordinate system guided by the extracted centerlines. By using a Hidden Markov Model (HMM), image intensity information from CTA and geometric information of extracted coronary arteries are combined to align coronary arteries. After registration, the pathological features in two straightened coronary arteries can be directly visualized side by side by synchronizing the corresponding cross-sectional slices and circumferential rotation angles. By evaluating with manually labeled landmarks, the average distance error is 1.6 mm. PMID:26736676

  19. Visual quality assessment of watermarked medical images

    NASA Astrophysics Data System (ADS)

    Dowling, Jason A.; Planitz, Birgit M.; Maeder, Anthony J.; Du, Jiang; Pham, Binh; Boyd, Colin; Chen, Shaokang; Bradley, Andrew P.; Crozier, Stuart

    2007-03-01

    Increasing transmission of medical images across multiple user systems raises concerns for image security. Hiding watermark information in medical image data files is one solution for enhancing security and privacy protection of data. Medical image watermarking however is not a widely studied area, due partially to speculations on loss in viewer performance caused by degradation of image information. Such concerns are addressed if the amount of information lost due to watermarking can be kept at minimal levels and below visual perception thresholds. This paper describes experiments where three alternative visual quality metrics were used to assess the degradation caused by watermarking medical images. Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) medical images were watermarked using different methods: Block based Discrete Cosine Transform (DCT) and Discrete Wavelet Transform (DWT) with various embedding strengths. The visual degradation of each watermarking parameter setting was assessed using Peak Signal-to-Noise Ratio (PSNR), Structural Similarity Measure (SSIM) and Steerable Visual Difference Predictor (SVDP) numerical metrics. The suitability of each of the three numerical metrics for medical image watermarking visual quality assessment is noted. In addition, subjective test results from human observers are used to suggest visual degradation thresholds.

  20. Quality indicators of image-based overlay

    NASA Astrophysics Data System (ADS)

    Chen, Yen-Liang; Huang, Jacky; Lee, Rita; Wang, Chen-Ming; Ke, Chih-Ming; Gau, Tsai-Sheng

    2012-03-01

    A new method for indicating the image quality of overlay measurement is proposed in this paper. Due to the constraint of the overlay control tolerance, the overlay metrology requirement has become very stringent. Current indicators such as the total measurement uncertainty (TMU) are insufficient to guarantee a good overlay measurement. This paper describes two quality indicators, the contrast index (CI) and the asymmetry index (AI). The CI is a crucial quality indicator that affects the overlay accuracy greatly. The AI, based on an imaging process with modified cross-correlation operation, shows alignment mark robustness in both the x and the y directions. For determination of the best recipe, the box-in-box overlay marks are measured to obtain the images with different conditions. The conventional TMU indicators are used first to sieve out the better choices. Then the CI and AI can help to judge whether the overlay results are reliable and can be applied to monitoring of process variations.

  1. Evaluation of Right Ventricular Myocardial Mechanics using Velocity Vector Imaging of Cardiac MRI Cine Images in Transposition of the Great Arteries Following Atrial and Arterial Switch Operations

    PubMed Central

    Thattaliyath, Bijoy D.; Forsha, Daniel E.; Stewart, Chad; Barker, Piers C.A.; Campbell, Michael J.

    2016-01-01

    Objective The aim of the study was to determine right and left ventricle deformation parameters in patients with transposition of the great arteries who had undergone atrial or arterial switch procedures. Setting Patients with transposition are born with a systemic right ventricle. Historically, the atrial switch operation, in which the right ventricle remains the systemic ventricle, was performed. These patients have increased rates of morbidity and mortality. We used cardiac MRI with Velocity Vector Imaging analysis to characterize and compare ventricular myocardial deformation in patients who had an atrial switch or arterial switch operation. Design Patients with a history of these procedures, who had a clinically ordered cardiac MRI were included in the study. Consecutive 20 patients (75% males, 28.7±1.8 years) who underwent atrial switch operation and 20 patients (60% males, 17.7±1.9 years) who underwent arterial switch operation were included in the study. Four chamber and short-axis cine images were used to determine longitudinal and circumferential strain and strain rate using Vector Velocity Imaging software. Results Compared to the arterial switch group, the atrial switch group had decreased right ventricular ejection fraction and increased end-diastolic and end-systolic volumes; and no difference in left ventricular ejection fraction and volumes. The atrial switch group had decreased longitudinal and circumferential strain and strain rate. When compared to normal controls multiple strain parameters in the atrial switch group were reduced. Conclusions Myocardial deformation analysis of transposition patients reveals a reduction of right ventricular function and decreased longitudinal and circumferential strain parameters in patients with an atrial switch operation compared to those with arterial switch operation. A better understanding of the mechanisms of RV failure in TGA may lead to improved therapies and adaptation. PMID:25655213

  2. 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.

  3. Continuous arterial positron monitor for quantitation in PET imaging.

    PubMed

    Nelson, A D; Muzic, R F; Miraldi, F; Muswick, G J; Leisure, G P; Voelker, W

    1990-01-01

    Quantitative measures of physiologic function with PET require continuous monitoring of arterial positron isotope concentration. A device has been developed that automates this process. This device has advantages over manual sampling techniques with syringes since fewer personnel are required, measurements are less error prone, and more continuous measures of arterial positron concentration are available. A constant flow infusion/withdrawal pump withdraws blood from the radial artery through a catheter connected to 0.5 mm inner diameter teflon tubing. This tubing is wrapped around a 50 mm thick by 50 mm diameter NaI(T1) crystal that is interfaced to a photomultiplier tube (PMT) and encased in a cylindrical lead shield. This crystal detects 511 Kev photons that result from positron annihilation. The device sensitivity is greater than 240 (cts/sec)/(microCi/ml) corresponding to a peak activity of approximately 10,000 cts/sec for a 50 mCi bolus injection in an adult. The system dynamic response has been measured and the true arterial input function is recovered by deconvolution. The system has been used clinically for more than 400 human PET studies and has been a reliable continuous monitor of arterial positron concentration. PMID:2252609

  4. Application of 270 mgI/mL Iodinated Contrast Media in Dual-Source Computed Tomography Coronary Artery Imaging

    PubMed Central

    Zhang, Jun; He, Bo; Wang, Yuan-Ling; Han, Dan

    2014-01-01

    Background This study aimed to explore the application of 270 mg I/mL iodinated contrast agent with a tube voltage of 100 kV scanning in coronary computed tomography angiography (CCTA). Methods This CCTA study was a prospective observational study. The two radiologists were blinded to both patient information and image date arrangement. One-hundred twenty patients (body mass index < 25.0 kg/m2) were randomly divided into three groups based on contrast agent concentrations of 370, 320, and 270 mg I/mL, scanning at an injection rate of 5 ml/s. Then, the coronary artery branches of the three groups were compared, and the display rate, mean computed tomography (CT) value, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), image noise, and radiation dose were analyzed. Results The artery display rates of the four main branches of coronaries in the three groups were all 100%, and the difference in the display rates of the remaining small branches in the three groups exhibited no statistical significance (p > 0.05). A comparison of the mean CT value of the coronary artery of three groups in the ascending aorta, descending aorta, left main, left ventricular wall, right coronary artery, left anterior descending, and left circumflex showed a statistically significant difference (p < 0.05). A comparison of the SNR, CNR, image noise, and radiation dose showed no statistically significant difference (p > 0.05). Conclusions Using a tube voltage of 100 kV combined with 270 mg I/mL iodinated contrast media in CCTA examination can achieve the “double low dose” effect while ensuring image quality. PMID:27122832

  5. Reduced-reference quality metrics for measuring the image quality of digitally printed natural images

    NASA Astrophysics Data System (ADS)

    Nuutinen, Mikko; Halonen, Raisa; Leisti, Tuomas; Oittinen, Pirkko

    2010-01-01

    The goal of the study was to develop a method for quality computation of digitally printed images. We wanted to use only the attributes which have a meaning for subjective visual quality experience of digitally printed images. Based on the subjective data and our assessments the attributes for quality calculation were sharpness, graininess and color contrast. The proposed graininess metric divides the fine detail image into blocks and used the low energy blocks for graininess calculation. The proposed color contrast metric computes the contrast of dominant colors using the coarse scale image. The proposed sharpness metric divides the coarse scale image into blocks and uses the high energy blocks for sharpness calculation. The reduced reference features of sharpness and graininess metrics are the numbers of high or low energy blocks. The reduced reference features of the color contrast metric are the directions of the dominant colors in reference image. The overall image quality was calculated by combining the values. The performance of proposed application specific image quality metric was high compared to the state of the art reduced reference applicationindependent image quality metric. Linear correlation coefficients between subjective and predicted MOS were 0.88 for electrophotography and 0.98 for ink-jet printed samples, for a sample set of 21 prints for electrophotography and for inkjet, subjectively evaluated by 28 observers.

  6. Robust approach for color image quality assessment

    NASA Astrophysics Data System (ADS)

    Le Callet, Patrick; Barba, Dominique

    2003-06-01

    This paper presents a visual color image quality metric assessment with full reference image. The metric is highly based on human visual system properties in order to get the best correspondence with human judgements. Contrary to some others objective criteria, it doesn't use any a priori knowledge on the type of introduced degradations. So the main interest of the metric is on its ability to produce robust results independently of the distortions. The metric can be decomposed into two steps. The first one projects each images, the reference one and the distorted one, in a perceptual space. The second step achieves the pooling of errors between perceptual representation of two images in order to get a score for the overall quality. Since we have shown that these two steps have equivalent importance regarding metric performance, we have particularly paid attention in correct balancing when designing the two steps. Especially, for the second one, that is generally limited to poor consideration in literature, we have developed some new original approaches . We compare results of the metric with human judgments on images distorted with different compression schemes. High performances are obtained leading to assure that the metric is robust, so this approach constitutes an alternative useful tool to PSNR for image quality assessment.

  7. 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.

  8. 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.

  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. 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.

  11. 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.

  12. Whole-brain perfusion imaging with balanced steady-state free precession arterial spin labeling.

    PubMed

    Han, Paul Kyu; Ye, Jong Chul; Kim, Eung Yeop; Choi, Seung Hong; Park, Sung-Hong

    2016-03-01

    Recently, balanced steady-state free precession (bSSFP) readout has been proposed for arterial spin labeling (ASL) perfusion imaging to reduce susceptibility artifacts at a relatively high spatial resolution and signal-to-noise ratio (SNR). However, the main limitation of bSSFP-ASL is the low spatial coverage. In this work, methods to increase the spatial coverage of bSSFP-ASL are proposed for distortion-free, high-resolution, whole-brain perfusion imaging. Three strategies of (i) segmentation, (ii) compressed sensing (CS) and (iii) a hybrid approach combining the two methods were tested to increase the spatial coverage of pseudo-continuous ASL (pCASL) with three-dimensional bSSFP readout. The spatial coverage was increased by factors of two, four and six using each of the three approaches, whilst maintaining the same total scan time (5.3 min). The number of segments and/or CS acceleration rate (R) correspondingly increased to maintain the same bSSFP readout time (1.2 s). The segmentation approach allowed whole-brain perfusion imaging for pCASL-bSSFP with no penalty in SNR and/or total scan time. The CS approach increased the spatial coverage of pCASL-bSSFP whilst maintaining the temporal resolution, with minimal impact on the image quality. The hybrid approach provided compromised effects between the two methods. Balanced SSFP-based ASL allows the acquisition of perfusion images with wide spatial coverage, high spatial resolution and SNR, and reduced susceptibility artifacts, and thus may become a good choice for clinical and neurological studies. Copyright © 2015 John Wiley & Sons, Ltd. PMID:26676386

  13. Image Quality in Analog and Digital Microtechniques.

    ERIC Educational Resources Information Center

    White, William

    1991-01-01

    Discusses the basic principles of the application of microfilm (analog) and electronic (digital) technologies for data storage. Image quality is examined, searching and retrieval capabilities are considered, and hardcopy output resolution is described. It is concluded that microfilm is still the preferred archival medium. (5 references) (LRW)

  14. Quality evaluation of fruit by hyperspectral imaging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This chapter presents new applications of hyperspectral imaging for measuring the optical properties of fruits and assessing their quality attributes. A brief overview is given of current techniques for measuring optical properties of turbid and opaque biological materials. Then a detailed descripti...

  15. A framework for automated coronary artery tracking of low axial resolution multi slice CT images

    NASA Astrophysics Data System (ADS)

    Wu, Jing; Ferns, Gordon; Giles, John; Lewis, Emma

    2011-03-01

    Low axial resolution data such as multi-slice CT(MSCT) used for coronary artery disease screening must balance the potential loss in image clarity, detail and partial volume effects with the benefits to the patient such as faster acquisition time leading to lower dose exposure. In addition, tracking of the coronary arteries can aid the location of objects contained within, thus helping to differentiate them from similar in appearance, difficult to discern neighbouring regions. A fully automated system has been developed to segment and track the main coronary arteries and visualize the results. Automated heart isolation is carried out for each slice of an MSCT image using active contour methods. Ascending aorta and artery root segmentation is performed using a combination of active contours, morphological operators and geometric analysis of coronary anatomy to identify a starting point for vessel tracking. Artery tracking and backtracking employs analysis of vessel position combined with segmented region shape analysis to obtain artery paths. Robust, accurate threshold parameters are calculated for segmentation utilizing Gaussian Mixture Model fitting and analysis. The low axial resolution of our MSCT data sets, in combination with poor image clarity and noise presented the greatest challenge. Classification techniques such as shape analysis have been utilized to good effect and our results to date have shown that such deficiencies in the data can be overcome, further promoting the positive benefits to patients.

  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. Scene reduction for subjective image quality assessment

    NASA Astrophysics Data System (ADS)

    Lewandowska (Tomaszewska), Anna

    2016-01-01

    Evaluation of image quality is important for many image processing systems, such as those used for acquisition, compression, restoration, enhancement, or reproduction. Its measurement is often accompanied by user studies, in which a group of observers rank or rate results of several algorithms. Such user studies, known as subjective image quality assessment experiments, can be very time consuming and do not guarantee conclusive results. This paper is intended to help design an efficient and rigorous quality assessment experiment. We propose a method of limiting the number of scenes that need to be tested, which can significantly reduce the experimental effort and still capture relevant scene-dependent effects. To achieve it, we employ a clustering technique and evaluate it on the basis of compactness and separation criteria. The correlation between the results obtained from a set of images in an initial database and the results received from reduced experiment are analyzed. Finally, we propose a procedure for reducing the initial scenes number. Four different assessment techniques were tested: single stimulus, double stimulus, forced choice, and similarity judgments. We conclude that in most cases, 9 to 12 judgments per evaluated algorithm for a large scene collection is sufficient to reduce the initial set of images.

  18. 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.

  19. ASAP (Automatic Software for ASL Processing): A toolbox for processing Arterial Spin Labeling images.

    PubMed

    Mato Abad, Virginia; García-Polo, Pablo; O'Daly, Owen; Hernández-Tamames, Juan Antonio; Zelaya, Fernando

    2016-04-01

    The method of Arterial Spin Labeling (ASL) has experienced a significant rise in its application to functional imaging, since it is the only technique capable of measuring blood perfusion in a truly non-invasive manner. Currently, there are no commercial packages for processing ASL data and there is no recognized standard for normalizing ASL data to a common frame of reference. This work describes a new Automated Software for ASL Processing (ASAP) that can automatically process several ASL datasets. ASAP includes functions for all stages of image pre-processing: quantification, skull-stripping, co-registration, partial volume correction and normalization. To assess the applicability and validity of the toolbox, this work shows its application in the study of hypoperfusion in a sample of healthy subjects at risk of progressing to Alzheimer's disease. ASAP requires limited user intervention, minimizing the possibility of random and systematic errors, and produces cerebral blood flow maps that are ready for statistical group analysis. The software is easy to operate and results in excellent quality of spatial normalization. The results found in this evaluation study are consistent with previous studies that find decreased perfusion in Alzheimer's patients in similar regions and demonstrate the applicability of ASAP. PMID:26612079

  20. 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.

  1. Quantitative statistical methods for image quality assessment.

    PubMed

    Dutta, Joyita; Ahn, Sangtae; Li, Quanzheng

    2013-01-01

    Quantitative measures of image quality and reliability are critical for both qualitative interpretation and quantitative analysis of medical images. While, in theory, it is possible to analyze reconstructed images by means of Monte Carlo simulations using a large number of noise realizations, the associated computational burden makes this approach impractical. Additionally, this approach is less meaningful in clinical scenarios, where multiple noise realizations are generally unavailable. The practical alternative is to compute closed-form analytical expressions for image quality measures. The objective of this paper is to review statistical analysis techniques that enable us to compute two key metrics: resolution (determined from the local impulse response) and covariance. The underlying methods include fixed-point approaches, which compute these metrics at a fixed point (the unique and stable solution) independent of the iterative algorithm employed, and iteration-based approaches, which yield results that are dependent on the algorithm, initialization, and number of iterations. We also explore extensions of some of these methods to a range of special contexts, including dynamic and motion-compensated image reconstruction. While most of the discussed techniques were developed for emission tomography, the general methods are extensible to other imaging modalities as well. In addition to enabling image characterization, these analysis techniques allow us to control and enhance imaging system performance. We review practical applications where performance improvement is achieved by applying these ideas to the contexts of both hardware (optimizing scanner design) and image reconstruction (designing regularization functions that produce uniform resolution or maximize task-specific figures of merit). PMID:24312148

  2. Quantitative Statistical Methods for Image Quality Assessment

    PubMed Central

    Dutta, Joyita; Ahn, Sangtae; Li, Quanzheng

    2013-01-01

    Quantitative measures of image quality and reliability are critical for both qualitative interpretation and quantitative analysis of medical images. While, in theory, it is possible to analyze reconstructed images by means of Monte Carlo simulations using a large number of noise realizations, the associated computational burden makes this approach impractical. Additionally, this approach is less meaningful in clinical scenarios, where multiple noise realizations are generally unavailable. The practical alternative is to compute closed-form analytical expressions for image quality measures. The objective of this paper is to review statistical analysis techniques that enable us to compute two key metrics: resolution (determined from the local impulse response) and covariance. The underlying methods include fixed-point approaches, which compute these metrics at a fixed point (the unique and stable solution) independent of the iterative algorithm employed, and iteration-based approaches, which yield results that are dependent on the algorithm, initialization, and number of iterations. We also explore extensions of some of these methods to a range of special contexts, including dynamic and motion-compensated image reconstruction. While most of the discussed techniques were developed for emission tomography, the general methods are extensible to other imaging modalities as well. In addition to enabling image characterization, these analysis techniques allow us to control and enhance imaging system performance. We review practical applications where performance improvement is achieved by applying these ideas to the contexts of both hardware (optimizing scanner design) and image reconstruction (designing regularization functions that produce uniform resolution or maximize task-specific figures of merit). PMID:24312148

  3. No-reference image quality metric based on image classification

    NASA Astrophysics Data System (ADS)

    Choi, Hyunsoo; Lee, Chulhee

    2011-12-01

    In this article, we present a new no-reference (NR) objective image quality metric based on image classification. We also propose a new blocking metric and a new blur metric. Both metrics are NR metrics since they need no information from the original image. The blocking metric was computed by considering that the visibility of horizontal and vertical blocking artifacts can change depending on background luminance levels. When computing the blur metric, we took into account the fact that blurring in edge regions is generally more sensitive to the human visual system. Since different compression standards usually produce different compression artifacts, we classified images into two classes using the proposed blocking metric: one class that contained blocking artifacts and another class that did not contain blocking artifacts. Then, we used different quality metrics based on the classification results. Experimental results show that each metric correlated well with subjective ratings, and the proposed NR image quality metric consistently provided good performance with various types of content and distortions.

  4. Fourier transform based scalable image quality measure.

    PubMed

    Narwaria, Manish; Lin, Weisi; McLoughlin, Ian; Emmanuel, Sabu; Chia, Liang-Tien

    2012-08-01

    We present a new image quality assessment (IQA) algorithm based on the phase and magnitude of the 2D (twodimensional) Discrete Fourier Transform (DFT). The basic idea is to compare the phase and magnitude of the reference and distorted images to compute the quality score. However, it is well known that the Human Visual Systems (HVSs) sensitivity to different frequency components is not the same. We accommodate this fact via a simple yet effective strategy of nonuniform binning of the frequency components. This process also leads to reduced space representation of the image thereby enabling the reduced-reference (RR) prospects of the proposed scheme. We employ linear regression to integrate the effects of the changes in phase and magnitude. In this way, the required weights are determined via proper training and hence more convincing and effective. Lastly, using the fact that phase usually conveys more information than magnitude, we use only the phase for RR quality assessment. This provides the crucial advantage of further reduction in the required amount of reference image information. The proposed method is therefore further scalable for RR scenarios. We report extensive experimental results using a total of 9 publicly available databases: 7 image (with a total of 3832 distorted images with diverse distortions) and 2 video databases (totally 228 distorted videos). These show that the proposed method is overall better than several of the existing fullreference (FR) algorithms and two RR algorithms. Additionally, there is a graceful degradation in prediction performance as the amount of reference image information is reduced thereby confirming its scalability prospects. To enable comparisons and future study, a Matlab implementation of the proposed algorithm is available at http://www.ntu.edu.sg/home/wslin/reduced_phase.rar. PMID:22562758

  5. Intra-arterial catheter for simultaneous microstructural and molecular imaging in vivo

    PubMed Central

    Yoo, Hongki; Kim, Jin Won; Shishkov, Milen; Namati, Eman; Morse, Theodore; Shubochkin, Roman; McCarthy, Jason R; Ntziachristos, Vasilis; Bouma, Brett E; Jaffer, Farouc A; Tearney, Guillermo J

    2011-01-01

    Advancing our understanding of human coronary artery disease requires new methods that can be used in patients for studying atherosclerotic plaque microstructure in relation to the molecular mechanisms that underlie its initiation, progression, and clinical complications, including myocardial infarction and sudden cardiac death. Here we report a dual-modality intra-arterial catheter for simultaneous microstructural and molecular imaging in vivo using a combination of optical frequency domain imaging (OFDI) and near-infrared fluorescence (NIRF) imaging. By providing simultaneous molecular information in the context of the surrounding tissue microstructure, this novel catheter could provide new opportunities for investigating coronary atherosclerosis and stent healing, and for identifying high-risk biological and structural coronary arterial plaques in vivo. PMID:22057345

  6. Intra-arterial catheter for simultaneous microstructural and molecular imaging in vivo.

    PubMed

    Yoo, Hongki; Kim, Jin Won; Shishkov, Milen; Namati, Eman; Morse, Theodore; Shubochkin, Roman; McCarthy, Jason R; Ntziachristos, Vasilis; Bouma, Brett E; Jaffer, Farouc A; Tearney, Guillermo J

    2011-12-01

    Advancing understanding of human coronary artery disease requires new methods that can be used in patients for studying atherosclerotic plaque microstructure in relation to the molecular mechanisms that underlie its initiation, progression and clinical complications, including myocardial infarction and sudden cardiac death. Here we report a dual-modality intra-arterial catheter for simultaneous microstructural and molecular imaging in vivo using a combination of optical frequency domain imaging (OFDI) and near-infrared fluorescence (NIRF) imaging. By providing simultaneous molecular information in the context of the surrounding tissue microstructure, this new catheter could provide new opportunities for investigating coronary atherosclerosis and stent healing and for identifying high-risk biological and structural coronary arterial plaques in vivo. PMID:22057345

  7. Live 3D image overlay for arterial duct closure with Amplatzer Duct Occluder II additional size.

    PubMed

    Goreczny, Sebstian; Morgan, Gareth J; Dryzek, Pawel

    2016-03-01

    Despite several reports describing echocardiography for the guidance of ductal closure, two-dimensional angiography remains the mainstay imaging tool; three-dimensional rotational angiography has the potential to overcome some of the drawbacks of standard angiography, and reconstructed image overlay provides reliable guidance for device placement. We describe arterial duct closure solely from venous approach guided by live three-dimensional image overlay. PMID:26358032

  8. Automatic segmentation of the lumen of the carotid artery in ultrasound B-mode images

    NASA Astrophysics Data System (ADS)

    Santos, André M. F.; Tavares, Jão. Manuel R. S.; Sousa, Luísa; Santos, Rosa; Castro, Pedro; Azevedo, Elsa

    2013-02-01

    A new algorithm is proposed for the segmentation of the lumen and bifurcation boundaries of the carotid artery in B-mode ultrasound images. It uses the hipoechogenic characteristics of the lumen for the identification of the carotid boundaries and the echogenic characteristics for the identification of the bifurcation boundaries. The image to be segmented is processed with the application of an anisotropic diffusion filter for speckle removal and morphologic operators are employed in the detection of the artery. The obtained information is then used in the definition of two initial contours, one corresponding to the lumen and the other to the bifurcation boundaries, for the posterior application of the Chan-vese level set segmentation model. A set of longitudinal B-mode images of the common carotid artery (CCA) was acquired with a GE Healthcare Vivid-e ultrasound system (GE Healthcare, United Kingdom). All the acquired images include a part of the CCA and of the bifurcation that separates the CCA into the internal and external carotid arteries. In order to achieve the uppermost robustness in the imaging acquisition process, i.e., images with high contrast and low speckle noise, the scanner was adjusted differently for each acquisition and according to the medical exam. The obtained results prove that we were able to successfully apply a carotid segmentation technique based on cervical ultrasonography. The main advantage of the new segmentation method relies on the automatic identification of the carotid lumen, overcoming the limitations of the traditional methods.

  9. Numerical environment for simulating 3D angiographic imaging of the coronary arteries

    NASA Astrophysics Data System (ADS)

    Lehmann, Glen; Habets, Damiaan F.; Holdsworth, David W.; Drangova, Maria

    2002-05-01

    A realistic numerical environment for simulating three-dimensional (3D) angiographic imaging of the coronary arteries has been developed. Through numerical simulation we propose to optimize acquisition and gating strategies, aiding in the design of 3D coronary imaging systems. We have previously developed a dynamic model of the coronary arteries, based on a high-resolution 3D image of an excised human heart, which was perfused with iodinated contrast agent. To mimic the motion of the arteries during the cardiac cycle, the motion of the vessel branch points was determined from cine bi-plane coronary angiograms of a patient with vessel anatomy similar to the excised heart. The static image was then non-linearly deformed to produce a sequence of volumetric images, with isotropic 0.4-mm resolution, representing the motion of the coronary arteries throughout the cardiac cycle. To simulate different acquisition strategies we have developed an algorithm to forward project through the volume data sets. The geometry of the CT system used to acquire the original 3D image of the static heart is mimicked in the re-projection algorithm. Thus, prospective radiographic projections corresponding to any projection-angle can be produced for any time -point throughout the cardiac cycle. Combining re-projections from selected time-points and view angles enables the evaluation of various acquisition and gating strategies.

  10. 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.

  11. 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

  12. 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.

  13. Image quality control in breast ultrasound.

    PubMed

    Lagalla, R; Midiri, M

    1998-05-01

    Sonography is well suited for breast studies. Adequate equipment is needed to acquire high quality images because several technical factors influence ultrasound images. Thus, the use of high frequency dynamic scanning probes, the ultrasound beam focusing corrected for the near field, the adjustment of the gain and image contrast may all interfere with ultrasound beam reflection and scattering, determined by the heterogeneity of the gland parenchyma. In the last few years, a line of ultrasound equipment dedicated to this kind of application has been developed with 'small parts' transducers and frequencies ranging 10-13 MHz. These units can improve the evaluation of superficial structures and provide diagnostic results that conventional equipment cannot achieve. The higher the quality, the more a sonographic image corresponds to real anatomy. This capability depends on the different kinds of system resolution. Axial spatial resolution is the capability to resolve discrete structures along the beam axis. Pulse length is inversely proportional to frequency and thus, the higher the transducer frequency, the better the axial resolution. However, the increase in frequency reduces the depth of penetration of the ultrasound beam. The spectrum of frequencies emitted by the crystal has been recently modified in order to obtain a good trade-off between the beam resolution and its penetration. Indeed, the development of the multifrequency technology allowed to improve the near field resolution while retaining a good penetration into the distant field. Furthermore, the use of compound ceramics with a broad bandwidth helps Doppler analysis because flow studies are optimized by low frequencies, whereas two-dimensional morphologic imaging is optimized by high frequencies. Lateral spatial resolution is the capability to resolve discrete structures perpendicular or lateral to the beam axis. This parameter strictly depends on the size of the ultrasound beam section and it is optimal only in the focal area. Therefore, it improves with narrow beams. Several transducers are available in breast sonography, but the most adequate one is currently the annular transducer. The equipment should be able to detect even slight differences in acoustic impedance between the several breast tissues. This may be obtained by optimizing the dynamic range and the pre- and postprocessing setting. Apart from equipment, two other technical factors should be optimized to obtain high quality images, namely beam intensity and gain curve. A new Doppler technique has been recently introduced: power Doppler, which allows the demonstration of breast nodule vascularization with higher sensitivity than color Doppler. Finally, a rigorous examination technique is required to obtain high quality images. In the last few years, several quality assurance programs have been introduced. Dedicated phantoms are generally used. Recently, computer systems have been also developed. PMID:9652527

  14. Retinal image quality in the rodent eye.

    PubMed

    Artal, P; Herreros de Tejada, P; Muñoz Tedó, C; Green, D G

    1998-01-01

    Many rodents do not see well. For a target to be resolved by a rat or a mouse, it must subtend a visual angle of a degree or more. It is commonly assumed that this poor spatial resolving capacity is due to neural rather than optical limitations, but the quality of the retinal image has not been well characterized in these animals. We have modified a double-pass apparatus, initially designed for the human eye, so it could be used with rodents to measure the modulation transfer function (MTF) of the eye's optics. That is, the double-pass retinal image of a monochromatic (lambda = 632.8 nm) point source was digitized with a CCD camera. From these double-pass measurements, the single-pass MTF was computed under a variety of conditions of focus and with different pupil sizes. Even with the eye in best focus, the image quality in both rats and mice is exceedingly poor. With a 1-mm pupil, for example, the MTF in the rat had an upper limit of about 2.5 cycles/deg, rather than the 28 cycles/deg one would obtain if the eye were a diffraction-limited system. These images are about 10 times worse than the comparable retinal images in the human eye. Using our measurements of the optics and the published behavioral and electrophysiological contrast sensitivity functions (CSFs) of rats, we have calculated the CSF that the rat would have if it had perfect rather than poor optics. We find, interestingly, that diffraction-limited optics would produce only slight improvement overall. That is, in spite of retinal images which are of very low quality, the upper limit of visual resolution in rodents is neurally determined. Rats and mice seem to have eyes in which the optics and retina/brain are well matched. PMID:9682864

  15. 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.

  16. Health maintenance organizations and hospital quality for coronary artery bypass surgery.

    PubMed

    Escarce, J J; Van Horn, R L; Pauly, M V; Williams, S V; Shea, J A; Chen, W

    1999-09-01

    This study uses hospital discharge data for 1992-1994 to assess differences between HMO and insured non-HMO patients in California and Florida with regard to the quality of the hospitals used for coronary artery bypass graft (CABG) surgery. The authors found that commercially insured HMO patients in California used higher quality hospitals than commercially insured non-HMO patients, controlling for patient distance to the hospital. In contrast, commercially insured HMO and non-HMO patients in Florida were similarly distributed across hospitals of different quality levels, whereas Medicare HMO patients in Florida used lower quality hospitals than patients in the standard Medicare program. The authors conclude that the association between HMO coverage and hospital quality may differ across geographic areas and patient populations, possibly related to the maturity and structure of managed care markets. PMID:10510608

  17. 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.

  18. 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

  19. Image quality assessment and human visual system

    NASA Astrophysics Data System (ADS)

    Gao, Xinbo; Lu, Wen; Tao, Dacheng; Li, Xuelong

    2010-07-01

    This paper summaries the state-of-the-art of image quality assessment (IQA) and human visual system (HVS). IQA provides an objective index or real value to measure the quality of the specified image. Since human beings are the ultimate receivers of visual information in practical applications, the most reliable IQA is to build a computational model to mimic the HVS. According to the properties and cognitive mechanism of the HVS, the available HVS-based IQA methods can be divided into two categories, i.e., bionics methods and engineering methods. This paper briefly introduces the basic theories and development histories of the above two kinds of HVS-based IQA methods. Finally, some promising research issues are pointed out in the end of the paper.

  20. 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

  1. 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

  2. Arterial disease in patients with human immunodeficiency virus infection: what has imaging taught us?

    PubMed

    Stein, James H; Currier, Judith S; Hsue, Priscilla Y

    2014-05-01

    With advances in antiretroviral therapy (ART), individuals with human immunodeficiency virus (HIV) infection are living longer and increasingly die of non-HIV-related diseases, such as cardiovascular disease (CVD). Several observational studies suggest that HIV-infected patients on ART are at increased risk of CVD; however, the precise mechanisms underlying the association between HIV infection and CVD risk are uncertain. Atherosclerosis and arterial disease in HIV-infected individuals is a multifactorial process with several potential targets for research and therapeutic intervention. This paper critically reviews the contributions of imaging to our understanding of arterial disease, atherosclerosis, and CVD risk in HIV-infected individuals. In general, the findings of studies using carotid ultrasound, coronary computed tomographic angiography, and aortic positron emission tomography agree with those from observational studies of CVD events and suggest that HIV infection is associated with an increased risk of CVD. Observational studies of CVD outcomes and studies using carotid intima-media thickness suggest that there is a moderate increase in CVD risk related to HIV serostatus. Less can be said about the role of ART and specific ART therapies in CVD risk, mainly because imaging studies have had serious methodological limitations that diminish their generalizability. Brachial artery reactivity testing has been especially useful for elucidating the arterial pathophysiology of HIV infection and its treatments, as well as the arterial effects of interventions for treating HIV and dyslipidemia. Aortic positron emission tomography has been especially useful for evaluating arterial inflammation. Coronary artery calcium has not proven to be a useful marker of subclinical atherosclerosis in HIV-infected individuals. Imaging studies support the intriguing hypothesis that persistent inflammation and immune dysregulation contribute to increased CVD risk among treated and suppressed patients with HIV infection. PMID:24831212

  3. A novel multiscale topo-morphometric approach for separating arteries and veins via pulmonary CT imaging

    NASA Astrophysics Data System (ADS)

    Saha, Punam K.; Gao, Zhiyun; Alford, Sara; Sonka, Milan; Hoffman, Eric

    2009-02-01

    Distinguishing arterial and venous trees in pulmonary multiple-detector X-ray computed tomography (MDCT) images (contrast-enhanced or unenhanced) is a critical first step in the quantification of vascular geometry for purposes of determining, for instance, pulmonary hypertension, using vascular dimensions as a comparator for assessment of airway size, detection of pulmonary emboli and more. Here, a novel method is reported for separating arteries and veins in MDCT pulmonary images. Arteries and veins are modeled as two iso-intensity objects closely entwined with each other at different locations at various scales. The method starts with two sets of seeds -- one for arteries and another for veins. Initialized with seeds, arteries and veins grow iteratively while maintaining their spatial separation and eventually forming two disjoint objects at convergence. The method combines fuzzy distance transform, a morphologic feature, with a topologic connectivity property to iteratively separate finer and finer details starting at a large scale and progressing towards smaller scales. The method has been validated in mathematically generated tubular objects with different levels of fuzziness, scale and noise. Also, it has been successfully applied to clinical CT pulmonary data. The accuracy of the method has been quantitatively evaluated by comparing its results with manual outlining. For arteries, the method has yielded correctness of 81.7% at the cost of 6.7% false positives and 11.6% false negatives. Our method is very promising for automated separation of arteries and veins in MDCT pulmonary images even when there is no mark of intensity variation at conjoining locations.

  4. Retinal image quality, reading and myopia.

    PubMed

    Collins, Michael J; Buehren, Tobias; Iskander, D Robert

    2006-01-01

    Analysis was undertaken of the retinal image characteristics of the best-spectacle corrected eyes of progressing myopes (n = 20, mean age = 22 years; mean spherical equivalent = -3.84 D) and a control group of emmetropes (n = 20, mean age = 23 years; mean spherical equivalent = 0.00 D) before and after a 2h reading task. Retinal image quality was calculated based upon wavefront measurements taken with a Hartmann-Shack sensor with fixation on both a far (5.5 m) and near (individual reading distance) target. The visual Strehl ratio based on the optical transfer function (VSOTF) was significantly worse for the myopes prior to reading for both the far (p = 0.01) and near (p = 0.03) conditions. The myopic group showed significant reductions in various aspects of retinal image quality compared with the emmetropes, involving components of the modulation transfer function, phase transfer function and point spread function, often along the vertical meridian of the eye. The depth of focus of the myopes (0.54 D) was larger (p = 0.02) than the emmetropes (0.42 D) and the distribution of refractive power (away from optimal sphero-cylinder) was greater in the myopic eyes (variance of distributions p < 0.05). We found evidence that the lead and lag of accommodation are influenced by the higher order aberrations of the eye (e.g. significant correlations between lead/lag and the peak of the visual Strehl ratio based on the MTF). This could indicate that the higher accommodation lags seen in myopes are providing optimized retinal image characteristics. The interaction between low and high order aberrations of the eye play a significant role in reducing the retinal image quality of myopic eyes compared with emmetropes. PMID:15913701

  5. Visual pattern degradation based image quality assessment

    NASA Astrophysics Data System (ADS)

    Wu, Jinjian; Li, Leida; Shi, Guangming; Lin, Weisi; Wan, Wenfei

    2015-08-01

    In this paper, we introduce a visual pattern degradation based full-reference (FR) image quality assessment (IQA) method. Researches on visual recognition indicate that the human visual system (HVS) is highly adaptive to extract visual structures for scene understanding. Existing structure degradation based IQA methods mainly take local luminance contrast to represent structure, and measure quality as degradation on luminance contrast. In this paper, we suggest that structure includes not only luminance contrast but also orientation information. Therefore, we analyze the orientation characteristic for structure description. Inspired by the orientation selectivity mechanism in the primary visual cortex, we introduce a novel visual pattern to represent the structure of a local region. Then, the quality is measured as the degradations on both luminance contrast and visual pattern. Experimental results on Five benchmark databases demonstrate that the proposed visual pattern can effectively represent visual structure and the proposed IQA method performs better than the existing IQA metrics.

  6. 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.

  7. Understanding the genetics of coronary artery disease through the lens of noninvasive imaging.

    PubMed

    Yang, Eunice; Vargas, Jose D; Bluemke, David A

    2012-01-01

    Coronary artery disease is a common condition 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 resulted in large-scale association studies, possibly adding to our current understanding of the genetics of coronary artery disease. Sifting through the statistical noise, however, requires the selection of 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. In this article, we propose that advances in imaging technology have generated improved phenotypic markers for genetic association studies of coronary artery disease. PMID:22149524

  8. Towards real-time image quality assessment

    NASA Astrophysics Data System (ADS)

    Geary, Bobby; Grecos, Christos

    2011-03-01

    We introduce a real-time implementation and evaluation of a new fast accurate full reference based image quality metric. The popular general image quality metric known as the Structural Similarity Index Metric (SSIM) has been shown to be an effective, efficient and useful, finding many practical and theoretical applications. Recently the authors have proposed an enhanced version of the SSIM algorithm known as the Rotated Gaussian Discrimination Metric (RGDM). This approach uses a Gaussian-like discrimination function to evaluate local contrast and luminance. RGDM was inspired by an exploration of local statistical parameter variations in relation to variation of Mean Opinion Score (MOS) for a range of particular distortion types. In this paper we out-line the salient features of the derivation of RGDM and show how analyses of local statistics of distortion type necessitate variation in discrimination function width. Results on the LIVE image database show tight banding of RGDM metric value when plotted against mean opinion score indicating the usefulness of this metric. We then explore a number of strategies for algorithmic speed-up including the application of Integral Images for patch based computation optimisation, cost reduction for the evaluation of the discrimination function and general loop unrolling. We also employ fast Single Instruction Multiple Data (SIMD) intrinsics and explore data parallel decomposition on a multi-core Intel Processor.

  9. Quantification of cross-sectional artery wall motion with IVUS image registration

    NASA Astrophysics Data System (ADS)

    Oakeson, Kevin D.; Zhu, Hui; Friedman, Morton H.

    2004-04-01

    Atherosclerotic lesions have been shown to have different mechanical properties than the non-diseased artery. Calculating vessel wall strain from cross-sectional vessel wall motions allows for the measurement of local stiffness. In this paper, a robust method is developed to track cross-sectional displacements of an artery wall using two different intravascular ultrasound (IVUS) images acquired at two different pressure levels respectively. First, the vessel wall region in one image is segmented semi-automatically by refining two spline-based contours to the locations of inner and outer vessel wall borders. Then the ringlike wall region in one image is registered to its counterpart in the other image in polar coordinates. The registration is performed by minimizing an energy function of the 2D motion field based on a spline-deformable-model. Both intensity and gradient information of the images are used to construct the energy function so that an accurate registration can be achieved. Registration accuracy was tested on simulated motions using IVUS images of a human coronary artery and a porcine carotid. The wall displacement fields calculated from real motion images are also demonstrated.

  10. 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

  11. Mirror Image Distal Anterior Cerebral Artery Aneurysms Treated with Coil Embolization

    PubMed Central

    Enesi, E.; Rroji, A.; Demneri, M.; Vreto, G.; Petrela, M.

    2013-01-01

    Summary Mirror image aneurysms of the distal anterior cerebral arteries (DACA) are rare. To the best of our knowledge this is the first case report of two patients with mirror image DACA aneurysms treated successfully with coil embolization. The association of aneurysms with anatomic variants has been extensively reported. We may speculate that the remnants of the failed regression of the supreme anterior communicating artery could lead to an increase in stress across their territorial bifurcation, leading to the development of mirror image DACA aneurysms. We found the endovascular treatment of mirror image DACA aneurysms to be feasible and effective. If possible, we suggest the treatment of both aneurysms in one procedure. PMID:23472723

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

    PubMed Central

    Meisner, Joshua K.; Niu, Jacqueline; Sumer, Suna

    2013-01-01

    Abstract. 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

  13. The improved algorithm for three-dimensional artery reconstruction of monoplane x-ray angiographic images

    NASA Astrophysics Data System (ADS)

    Huang, Yining; Zhang, Tianxu; Ma, Jinfeng; Wei, Yaxun

    2013-10-01

    Due to the curve of the coronary artery and the overlap, cross between its branches, some of its information is lost in the 3D-2D imaging process, which may leads to the inaccuracy in reconstructing three-dimensional vascular tree structure from angiographic images. In this paper, a new three-dimensional reconstruction method using overlap detection for 3-D projection is proposed to improve this problem, and experiments proves that the method can raise the accuracy of the reconstruction.

  14. 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

  15. 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.

  16. 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...

  17. Detection of coronary artery disease using MR imaging with dipyridamole infusion

    SciTech Connect

    Pennell, D.J.; Underwood, S.R.; Longmore, D.B. )

    1990-03-01

    Exercise testing in the magnetic resonance (MR) scanner is difficult because of space restriction and movement artefact, which limit its use in the investigation of patients with suspected coronary artery disease. Pharmacological stress, however, can be used as a substitute for exercise. Therefore, a patient with angina underwent MR ventricular wall motion studies before and after intravenous dipyridamole. Reversible abnormal regional contraction of the myocardium was demonstrated and correlated with a reversible perfusion defect on subsequent thallium myocardial perfusion imaging and a blocked artery at coronary angiography. A clinically useful investigative procedure may be developed.

  18. Interarterial course of the right coronary artery: assessment with cardiac computed tomography and myocardial perfusion imaging.

    PubMed

    Husmann, Lars; Valenta, Ines; Veit-Haibach, Patrick; Alkadhi, Hatem; Largiader, Thomas; Kaufmann, Philipp A

    2008-05-01

    A 50-year-old well-trained cyclist reported increasing brief episodes of chest pain over the last 8 years at maximum exercise during alpine bicycle training. Previous cardiac stress testing on a supine bicycle ergometer revealed nonspecific ST-T abnormalities. In June 2007, the patient was referred for computed tomography coronary angiography, which revealed a coronary anomaly, with the right coronary artery originating from the left coronary sinus and taking an interarterial course between the ascending aorta and the pulmonary trunk. There were no atherosclerotic alterations in the coronary arteries. Subsequent bicycle exercise stress and myocardial perfusion imaging revealed no myocardial perfusion defect. PMID:18431148

  19. Wall Imaging for Unilateral Intracranial Vertebral Artery Hypoplasia with Three-dimensional High-isotropic Resolution Magnetic Resonance Images

    PubMed Central

    Zhu, Xian-Jin; Wang, Wu; Du, Bin; Liu, Lei; He, Xin-Xin; Hu, Li-Bin; Zhang, Xue-Bin; Liu, Zun-Jing; Jiang, Wei-Jian

    2015-01-01

    Background: There are few studies for evaluating wall characteristics of intracranial vertebral artery hypoplasia (VAH). The aim of this study was to determine wall characteristics of VAH with three-dimensional volumetric isotropic turbo spin echo acquisition (3D VISTA) images and differentiate between acquired atherosclerotic stenosis and VAH. Methods: Thirty patients with suspicious VAH by luminograms were retrospectively enrolled between January 2014 and February 2015. The patients were classified as “acquired atherosclerotic stenosis” or “VAH” based on 3D VISTA images. The wall characteristics of VAH were assessed to determine the presence of atherosclerotic lesions, and the patients were classified into two subgroups (VAH with atherosclerosis and VAH with normal wall). Wall characteristics of basilar arteries and vertebral arteries were also assessed. The clinical and wall characteristics were compared between the two groups. Results: Five of 30 patients with suspicious VAH were finally diagnosed as acquired atherosclerotic stenosis by 3D VISTA images. 25 patients were finally diagnosed as VAH including 16 (64.00%) patients with atherosclerosis and 9 (36.00%) patients with normal wall. In the 16 patients with atherosclerosis, plaque was found in 9 patients, slight wall thickening in 6 patients, and thrombus and wall thickening in 1 patient. Compared with VAH patients with normal wall, VAH patients with atherosclerosis showed atherosclerotic basilar arteries and dominant vertebral arteries more frequently (P = 0.000). Conclusions: Three-dimensional VISTA images enable differentiation between the acquired atherosclerotic stenosis and VAH. VAH was also prone to atherosclerotic processes. PMID:26063361

  20. 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

  1. Arterial cross-section measurements from dual energy transvenous coronary angiography images

    SciTech Connect

    Chapman, D.; Schulze, C.

    1994-05-01

    The synchrotron based coronary angiography project at the National Synchrotron Light Source obtains images of coronary arteries using the digital subtraction technique after a distal venous injection of an iodine contrast agent. It allows two areal mass densities to be calculated from these images; one of the iodine and one of the water. Analysis procedures have been developed to arrive at these areal mass densities with corrections to the values being made for detector cross-talk and beam harmonics. From the iodine mass density distribution the relative arterial cross-section area is determined by a line integration across the arterial feature. Results will be given for an iodine tube phantom showing that the relative area of a feature whose lateral dimensions are smaller than the detector pixel resolution can be determined to a few percent. Also, results will be shown from a human image, showing the relative area of the right coronary artery mapped through a region of a previous stenosis subsequently treated by balloon angioplasty. Finally, limitation of the technique and plans to validate and improve the analysis will be discussed.

  2. IVUS Validation of Patient Coronary Artery Lumen Area Obtained from CT Images

    PubMed Central

    Luo, Tong; Wischgoll, Thomas; Kwon Koo, Bon; Huo, Yunlong; Kassab, Ghassan S.

    2014-01-01

    Aims Accurate computed tomography (CT)-based reconstruction of coronary morphometry (diameters, length, bifurcation angles) is important for construction of patient-specific models to aid diagnosis and therapy. The objective of this study is to validate the accuracy of patient coronary artery lumen area obtained from CT images based on intravascular ultrasound (IVUS). Methods and Results Morphometric data of 5 patient CT scans with 11 arteries from IVUS were reconstructed including the lumen cross sectional area (CSA), diameter and length. The volumetric data from CT images were analyzed at sub-pixel accuracy to obtain accurate vessel center lines and CSA. A new center line extraction approach was used where an initial estimated skeleton in discrete value was obtained using a traditional thinning algorithm. The CSA was determined directly without any circular shape assumptions to provide accurate reconstruction of stenosis. The root-mean-square error (RMSE) for CSA and diameter were 16.2% and 9.5% respectively. Conclusions The image segmentation and CSA extraction algorithm for reconstruction of coronary arteries proved to be accurate for determination of vessel lumen area. This approach provides fundamental morphometric data for patient-specific models to diagnose and treat coronary artery disease. PMID:24489811

  3. Effect of Bismuth Breast Shielding on Radiation Dose and Image Quality in Coronary CT Angiography

    PubMed Central

    Einstein, Andrew J.; Elliston, Carl D.; Groves, Daniel W.; Cheng, Bin; Wolff, Steven D.; Pearson, Gregory D. N.; Peters, M. Robert; Johnson, Lynne L.; Bokhari, Sabahat; Johnson, Gary W.; Bhatia, Ketan; Pozniakoff, Theodore; Brenner, David J.

    2011-01-01

    Background Coronary computed tomographic angiography (CCTA) is associated with high radiation dose to the female breasts. Bismuth breast shielding offers the potential to significantly reduce dose to the breasts and nearby organs, but the magnitude of this reduction and its impact on image quality and radiation dose have not been evaluated. Methods Radiation doses from CCTA to critical organs were determined using metal-oxide-semiconductor field-effect transistors positioned in a customized anthropomorphic whole-body dosimetry verification phantom. Image noise and signal were measured in regions of interest (ROIs) including the coronary arteries. Results With bismuth shielding, breast radiation dose was reduced 46–57% depending on breast size and scanning technique, with more moderate dose reduction to the heart, lungs, and esophagus. However, shielding significantly decreased image signal (by 14.6 HU) and contrast (by 28.4 HU), modestly but significantly increased image noise in ROIs in locations of coronary arteries, and decreased contrast-to-noise ratio by 20.9%.. Conclusions While bismuth breast shielding can significantly decrease radiation dose to critical organs, it is associated with an increase in image noise, decrease in contrast-to-noise, and changes tissue attenuation characteristics in the location of the coronary arteries. PMID:22068687

  4. High spatial and temporal resolution imaging of the arterial vasculature of the lower extremity with contrast enhanced MR angiography.

    PubMed

    Mostardi, Petrice M; Haider, Clifton R; Glockner, James F; Young, Phillip M; Riederer, Stephen J

    2011-05-01

    Vascular imaging can be essential in the diagnosis, monitoring, and planning and assessment of treatment of patients with peripheral vascular disease. The purpose of this work is to describe a recently developed three-dimensional (3D) time-resolved contrast-enhanced MR angiography (CE-MRA) technique, Cartesian Acquisition with Projection Reconstruction-like sampling (CAPR), and its application to imaging of the vasculature of the lower legs and feet. CAPR implements accelerated imaging techniques and uses specialized multielement imaging coil arrays to achieve high temporal and high spatial resolution imaging. Volunteer and patient studies of the vasculature of the lower legs and feet have been performed. Temporal resolution of 4.9-6.5 sec and spatial resolution less than or equal to 1 mm in all directions allow for the depiction of progressive arterial filling and complex flow patterns as well as sharp visualization of vascular structure as small as the fine muscular branches. High-quality diagnostic imaging is made possible with CAPR's advanced acquisition and reconstruction techniques and the use of specialized coil arrays. PMID:21509813

  5. On pictures and stuff: image quality and material appearance

    NASA Astrophysics Data System (ADS)

    Ferwerda, James A.

    2014-02-01

    Realistic images are a puzzle because they serve as visual representations of objects while also being objects themselves. When we look at an image we are able to perceive both the properties of the image and the properties of the objects represented by the image. Research on image quality has typically focused improving image properties (resolution, dynamic range, frame rate, etc.) while ignoring the issue of whether images are serving their role as visual representations. In this paper we describe a series of experiments that investigate how well images of different quality convey information about the properties of the objects they represent. In the experiments we focus on the effects that two image properties (contrast and sharpness) have on the ability of images to represent the gloss of depicted objects. We found that different experimental methods produced differing results. Specifically, when the stimulus images were presented using simultaneous pair comparison, observers were influenced by the surface properties of the images and conflated changes in image contrast and sharpness with changes in object gloss. On the other hand, when the stimulus images were presented sequentially, observers were able to disregard the image plane properties and more accurately match the gloss of the objects represented by the different quality images. These findings suggest that in understanding image quality it is useful to distinguish between quality of the imaging medium and the quality of the visual information represented by that medium.

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

    NASA Astrophysics Data System (ADS)

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

    2010-01-01

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

  7. Measuring multivariate subjective image quality for still and video cameras and image processing system components

    NASA Astrophysics Data System (ADS)

    Nyman, Göte; Leisti, Tuomas; Lindroos, Paul; Radun, Jenni; Suomi, Sini; Virtanen, Toni; Olives, Jean-Luc; Oja, Joni; Vuori, Tero

    2008-01-01

    The subjective quality of an image is a non-linear product of several, simultaneously contributing subjective factors such as the experienced naturalness, colorfulness, lightness, and clarity. We have studied subjective image quality by using a hybrid qualitative/quantitative method in order to disclose relevant attributes to experienced image quality. We describe our approach in mapping the image quality attribute space in three cases: still studio image, video clips of a talking head and moving objects, and in the use of image processing pipes for 15 still image contents. Naive observers participated in three image quality research contexts in which they were asked to freely and spontaneously describe the quality of the presented test images. Standard viewing conditions were used. The data shows which attributes are most relevant for each test context, and how they differentiate between the selected image contents and processing systems. The role of non-HVS based image quality analysis is discussed.

  8. Image analysis for dental bone quality assessment using CBCT imaging

    NASA Astrophysics Data System (ADS)

    Suprijanto; Epsilawati, L.; Hajarini, M. S.; Juliastuti, E.; Susanti, H.

    2016-03-01

    Cone beam computerized tomography (CBCT) is one of X-ray imaging modalities that are applied in dentistry. Its modality can visualize the oral region in 3D and in a high resolution. CBCT jaw image has potential information for the assessment of bone quality that often used for pre-operative implant planning. We propose comparison method based on normalized histogram (NH) on the region of inter-dental septum and premolar teeth. Furthermore, the NH characteristic from normal and abnormal bone condition are compared and analyzed. Four test parameters are proposed, i.e. the difference between teeth and bone average intensity (s), the ratio between bone and teeth average intensity (n) of NH, the difference between teeth and bone peak value (Δp) of NH, and the ratio between teeth and bone of NH range (r). The results showed that n, s, and Δp have potential to be the classification parameters of dental calcium density.

  9. 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

  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. The role of noninvasive imaging in coronary artery disease detection, prognosis, and clinical decision making.

    PubMed

    Dowsley, Taylor; Al-Mallah, Mouaz; Ananthasubramaniam, Karthik; Dwivedi, Girish; McArdle, Brian; Chow, Benjamin J W

    2013-03-01

    A vast array of noninvasive imaging modalities is available for the evaluation of the presence and severity of coronary artery disease (CAD). Choosing the right test can be challenging but is critical for proper patient diagnosis and management. Presently available imaging tests for CAD include: (1) nuclear myocardial perfusion imaging procedures (single-photon emission tomography) and positron emission tomography, (2) stress echocardiography, (3) computed tomography coronary angiography, and (4) cardiac magnetic resonance imaging. Exercise treadmill testing electrocardiography is another alternative that we will discuss briefly. Selection of the most appropriate imaging modality requires knowledge of the clinical question being addressed, patient characteristics (pretest probability and prevalence of disease), the strengths, limitations, risks, costs, and availability of each procedure. To assist with test selection, we review the relevant literature in detail to consider the relative merits of cardiac imaging modalities for: (1) detection of CAD, (2) risk stratification and prognostication, and (3) guiding clinical decision making. PMID:23357601

  12. Quality control of diffusion weighted images

    NASA Astrophysics Data System (ADS)

    Liu, Zhexing; Wang, Yi; Gerig, Guido; Gouttard, Sylvain; Tao, Ran; Fletcher, Thomas; Styner, Martin

    2010-03-01

    Diffusion Tensor Imaging (DTI) has become an important MRI procedure to investigate the integrity of white matter in brain in vivo. DTI is estimated from a series of acquired Diffusion Weighted Imaging (DWI) volumes. DWI data suffers from inherent low SNR, overall long scanning time of multiple directional encoding with correspondingly large risk to encounter several kinds of artifacts. These artifacts can be too severe for a correct and stable estimation of the diffusion tensor. Thus, a quality control (QC) procedure is absolutely necessary for DTI studies. Currently, routine DTI QC procedures are conducted manually by visually checking the DWI data set in a gradient by gradient and slice by slice way. The results often suffer from low consistence across different data sets, lack of agreement of different experts, and difficulty to judge motion artifacts by qualitative inspection. Additionally considerable manpower is needed for this step due to the large number of images to QC, which is common for group comparison and longitudinal studies, especially with increasing number of diffusion gradient directions. We present a framework for automatic DWI QC. We developed a tool called DTIPrep which pipelines the QC steps with a detailed protocoling and reporting facility. And it is fully open source. This framework/tool has been successfully applied to several DTI studies with several hundred DWIs in our lab as well as collaborating labs in Utah and Iowa. In our studies, the tool provides a crucial piece for robust DTI analysis in brain white matter study.

  13. Functional assessment of sequential coronary artery fistula and coronary artery stenosis with fractional flow reserve and stress adenosine myocardial perfusion imaging.

    PubMed

    Yew, Kuan Leong; Ooi, Poh Siang; Law, Chiong Soon

    2015-10-01

    Coronary artery fistula is an abnormal connection between one coronary artery to another coronary artery or cardiac chambers. The coronary artery fistula may cause significant shunting of blood and cause "pseudo-stenosis" or "steal phenomenon". This will also accentuate pre-existing mild-moderate de novo coronary lesions with resultant greater pressure gradient difference across the lesions. Thus, fractional flow reserve can be a useful tool to guide intervention decision on the coronary artery fistula. There are very few published reports regarding the use of FFR to assess coronary artery fistula. In fact, there is no outcome data regarding the deferment of coronary artery fistula intervention when the FFR is not physiologically significant. This case highlighted the use of FFR to evaluate the functional significance of coronary fistula in the setting of ischemia evaluation and it was proven to be safe to defer intervention with good 3 year clinical outcome. Stress adenosine myocardial perfusion imaging correlated with the FFR result. PMID:26557747

  14. 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

  15. Image Quality Characteristics of Handheld Display Devices for Medical Imaging

    PubMed Central

    Yamazaki, Asumi; Liu, Peter; Cheng, Wei-Chung; Badano, Aldo

    2013-01-01

    Handheld devices such as mobile phones and tablet computers have become widespread with thousands of available software applications. Recently, handhelds are being proposed as part of medical imaging solutions, especially in emergency medicine, where immediate consultation is required. However, handheld devices differ significantly from medical workstation displays in terms of display characteristics. Moreover, the characteristics vary significantly among device types. We investigate the image quality characteristics of various handheld devices with respect to luminance response, spatial resolution, spatial noise, and reflectance. We show that the luminance characteristics of the handheld displays are different from those of workstation displays complying with grayscale standard target response suggesting that luminance calibration might be needed. Our results also demonstrate that the spatial characteristics of handhelds can surpass those of medical workstation displays particularly for recent generation devices. While a 5 mega-pixel monochrome workstation display has horizontal and vertical modulation transfer factors of 0.52 and 0.47 at the Nyquist frequency, the handheld displays released after 2011 can have values higher than 0.63 at the respective Nyquist frequencies. The noise power spectra for workstation displays are higher than 1.2×10−5 mm2 at 1 mm−1, while handheld displays have values lower than 3.7×10−6 mm2. Reflectance measurements on some of the handheld displays are consistent with measurements for workstation displays with, in some cases, low specular and diffuse reflectance coefficients. The variability of the characterization results among devices due to the different technological features indicates that image quality varies greatly among handheld display devices. PMID:24236113

  16. Quality assessment for spectral domain optical coherence tomography (OCT) images.

    PubMed

    Liu, Shuang; Paranjape, Amit S; Elmaanaoui, Badr; Dewelle, Jordan; Rylander, H Grady; Markey, Mia K; Milner, Thomas E

    2009-01-01

    Retinal nerve fiber layer (RNFL) thickness, a measure of glaucoma progression, can be measured in images acquired by spectral domain optical coherence tomography (OCT). The accuracy of RNFL thickness estimation, however, is affected by the quality of the OCT images. In this paper, a new parameter, signal deviation (SD), which is based on the standard deviation of the intensities in OCT images, is introduced for objective assessment of OCT image quality. Two other objective assessment parameters, signal to noise ratio (SNR) and signal strength (SS), are also calculated for each OCT image. The results of the objective assessment are compared with subjective assessment. In the subjective assessment, one OCT expert graded the image quality according to a three-level scale (good, fair, and poor). The OCT B-scan images of the retina from six subjects are evaluated by both objective and subjective assessment. From the comparison, we demonstrate that the objective assessment successfully differentiates between the acceptable quality images (good and fair images) and poor quality OCT images as graded by OCT experts. We evaluate the performance of the objective assessment under different quality assessment parameters and demonstrate that SD is the best at distinguishing between fair and good quality images. The accuracy of RNFL thickness estimation is improved significantly after poor quality OCT images are rejected by automated objective assessment using the SD, SNR, and SS. PMID:20431701

  17. Non-invasive imaging in coronary artery disease including anatomical and functional evaluation of ischaemia and viability assessment

    PubMed Central

    Pakkal, M; Raj, V; Mccann, G P

    2011-01-01

    Coronary artery disease has an important impact on the morbidity and mortality statistics and health economics worldwide. Diagnosis of coronary artery disease is important in risk stratification and guides further management. Invasive coronary angiography is the traditional method of imaging the coronary arteries and remains the gold standard. It detects luminal stenosis but provides little information about the vessel wall or plaques. Besides, not all anatomical lesions are functionally significant. This has lent itself to a wide variety of imaging techniques to identify and assess a flow-limiting stenosis. The approach to diagnosis of coronary artery disease is broadly based on anatomical and functional imaging. Coronary CT and MRI of coronary arteries provide an anatomical assessment of coronary stenosis. Coronary calcium score and coronary CT assess subclinical atherosclerosis by assessing the atherosclerotic plaque burden. The haemodynamic significance of a coronary artery stenosis can be assessed by stress radioisotope studies, stress echocardiography and stress MRI. The more recent literature also focuses on plaque assessment and identification of plaques that are likely to give rise to an acute coronary syndrome. There is an explosion of literature on the merits and limitations of the different imaging modalities. This review article will provide an overview of all the imaging modalities in the diagnosis of coronary artery disease. PMID:22723535

  18. Arterial Wall Imaging in Symptomatic Carotid Stenosis: Delayed Enhancement on MDCT Angiography

    PubMed Central

    Ha, Su Min; Seo, Woo-Keun; Seol, Hae Young

    2016-01-01

    Objective To evaluate progressive enhancement in the carotid arterial wall overlying plaque in the symptomatic side for patients with cerebrovascular symptoms until delayed phase using MDCTA. Materials and Methods Twenty-one patients (all men; ages, 49-82 years; mean, 67.8 ± 8.4 years) with recent stroke and severe extracranial carotid stenosis were retrospectively analyzed. Pre-, early- and delayed phase images of MDCTA were obtained, and Hounsfield units (HU) of carotid walls were measured. We also measured HU of the asymptomatic contralateral carotid arterial wall for comparison. Friedman's test and Wilcoxon signed-rank test were used to evaluate the differences between groups. Results The averaged HU of the carotid wall in the symptomatic side was higher on the delayed phase (65.8 ± 14.2 HU) compared to early arterial phase (54.2 ± 12.6 HU). The averaged HU difference of wall enhancement between pre-contrast and delayed phase (28.0 ± 14.8 HU) was significantly higher than the between pre-contrast and early arterial phase (16.4 ± 12.1 HU) with P < 0.05. In analysis of the contralateral asymptomatic side, the HU difference between pre-contrast and delayed phase (15.5 ± 12.0 HU) showed no significant higher value than between pre-contrast and early arterial phase (14.9 ± 10.9 HU). Conclusion The pronounced enhancement of the carotid wall in the delayed phase on MDCTA was demonstrated in symptomatic patients with severe internal carotid artery stenosis. In the future, we need more comparative studies to verify this finding as one of risk stratification. PMID:26958408

  19. Comparison of exercise electrocardiography and quantitative thallium imaging for one-vessel coronary artery disease

    SciTech Connect

    Kaul, S.; Kiess, M.; Liu, P.; Guiney, T.E.; Pohost, G.M.; Okada, R.D.; Boucher, C.A.

    1985-08-01

    The relative value of exercise electrocardiography and computer analyzed thallium-201 imaging was compared in 124 patients with 1-vessel coronary artery disease (CAD). Of these, 78 had left anterior descending (LAD), 32 right and 14 left circumflex (LC) CAD. In patients with no previous myocardial infarction (MI), thallium imaging was more sensitive than the electrocardiogram (78% vs 64%, p less than 0.01), but in patients with previous MI, sensitivity was similar. Further, thallium imaging was more sensitive only in LAD and LC disease. Redistribution was compared with ST-segment depression as a marker of ischemia. Only in patients with prior MI (76% vs 44%, p less than 0.01) and only in LC and right CAD did redistribution occur more often than ST depression. Thallium imaging was more accurate in localizing stenoses than the electrocardiogram (p less than 0.001), but did not always correctly predict coronary anatomy. Septal thallium defects were associated with LAD disease in 84%, inferior defects with right CAD in 40% and posterolateral lesion defects with LC CAD in 22%. The results indicate the overall superiority of thallium imaging in 1-vessel CAD compared with exercise electrocardiography; however, there is a wide spectrum of extent and location of perfusion defects associated with each coronary artery. Thallium imaging complements coronary angiography by demonstrating the functional impact of CAD on myocardial perfusion.

  20. 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.

  1. Using short-wave infrared imaging for fruit quality evaluation

    NASA Astrophysics Data System (ADS)

    Zhang, Dong; Lee, Dah-Jye; Desai, Alok

    2013-12-01

    Quality evaluation of agricultural and food products is important for processing, inventory control, and marketing. Fruit size and surface quality are two important quality factors for high-quality fruit such as Medjool dates. Fruit size is usually measured by length that can be done easily by simple image processing techniques. Surface quality evaluation on the other hand requires more complicated design, both in image acquisition and image processing. Skin delamination is considered a major factor that affects fruit quality and its value. This paper presents an efficient histogram analysis and image processing technique that is designed specifically for real-time surface quality evaluation of Medjool dates. This approach, based on short-wave infrared imaging, provides excellent image contrast between the fruit surface and delaminated skin, which allows significant simplification of image processing algorithm and reduction of computational power requirements. The proposed quality grading method requires very simple training procedure to obtain a gray scale image histogram for each quality level. Using histogram comparison, each date is assigned to one of the four quality levels and an optimal threshold is calculated for segmenting skin delamination areas from the fruit surface. The percentage of the fruit surface that has skin delamination can then be calculated for quality evaluation. This method has been implemented and used for commercial production and proven to be efficient and accurate.

  2. 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

  3. LANDSAT-4 image data quality analysis

    NASA Technical Reports Server (NTRS)

    Anuta, P. E. (Principal Investigator)

    1982-01-01

    Work done on evaluating the geometric and radiometric quality of early LANDSAT-4 sensor data is described. Band to band and channel to channel registration evaluations were carried out using a line correlator. Visual blink comparisons were run on an image display to observe band to band registration over 512 x 512 pixel blocks. The results indicate a .5 pixel line misregistration between the 1.55 to 1.75, 2.08 to 2.35 micrometer bands and the first four bands. Also a four 30M line and column misregistration of the thermal IR band was observed. Radiometric evaluation included mean and variance analysis of individual detectors and principal components analysis. Results indicate that detector bias for all bands is very close or within tolerance. Bright spots were observed in the thermal IR band on an 18 line by 128 pixel grid. No explanation for this was pursued. The general overall quality of the TM was judged to be very high.

  4. 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

  5. Magnetic resonance imaging of perfusion using spin inversion of arterial water.

    PubMed Central

    Williams, D S; Detre, J A; Leigh, J S; Koretsky, A P

    1992-01-01

    A technique has been developed for proton magnetic resonance imaging (MRI) of perfusion, using water as a freely diffusable tracer, and its application to the measurement of cerebral blood flow (CBF) in the rat is demonstrated. The method involves labeling the inflowing water proton spins in the arterial blood by inverting them continuously at the neck region and observing the effects of inversion on the intensity of brain MRI. Solution to the Bloch equations, modified to include the effects of flow, allows regional perfusion rates to be measured from an image with spin inversion, a control image, and a T1 image. Continuous spin inversion labeling the arterial blood water was accomplished, using principles of adiabatic fast passage by applying continuous-wave radiofrequency power in the presence of a magnetic field gradient in the direction of arterial flow. In the detection slice used to measure perfusion, whole brain CBF averaged 1.39 +/- 0.19 ml.g-1.min-1 (mean +/- SEM, n = 5). The technique's sensitivity to changes in CBF was measured by using graded hypercarbia, a condition that is known to increase brain perfusion. CBF vs. pCO2 data yield a best-fit straight line described by CBF (ml.g-1.min-1) = 0.052pCO2 (mm Hg) - 0.173, in excellent agreement with values in the literature. Finally, perfusion images of a freeze-injured rat brain have been obtained, demonstrating the technique's ability to detect regional abnormalities in perfusion. Images PMID:1729691

  6. 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

  7. 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.

  8. Proceedings of Joint International Symposium on the role of noninvasive imaging modalities in clinical decision making of coronary artery disease

    SciTech Connect

    Mena, I.G.; Strauss, H.W.

    1986-01-01

    This report contains ten papers on the use of noninvasive imaging in clinical diagnosis and decision making. Topics include a cost analysis of magnetic resonance imaging in medical technology, diagnostic uses of MRI in chronic coronary artery disease, clinical applications of cine computed tomography, the use of PET as a clinical tool, and the use of echocardiography in coronary artery disease. Individual papers are processed separately for the data base. (TEM)

  9. 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

  10. 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

  11. Noncontrast MR Angiography of the Hand: Improved Arterial Conspicuity by Multi-Directional Flow-Sensitive Dephasing Magnetization Preparation in 3D Balanced SSFP Imaging

    PubMed Central

    Fan, Zhaoyang; Hodnett, Philip A.; Davarpanah, Amir H.; Scanlon, Timothy G.; Sheehan, John J.; Varga, John; Carr, James C.; Li, Debiao

    2011-01-01

    Purpose To develop a flow-sensitive dephasing (FSD) preparative scheme to facilitate multi-directional flow signal suppression in three-dimensional balanced steady-state free precession (SSFP) imaging and to validate the feasibility of the refined sequence for noncontrast MR angiography (NC-MRA) of the hand. Materials and Methods A new FSD preparative scheme was developed that combines two conventional FSD modules. Studies using a flow phantom (gadolinium doped water 15 cm/sec) and the hands of 11 healthy volunteers (6 males and 5 females) were performed to compare the proposed FSD scheme with its conventional counterpart with respect to the signal suppression of multi-directional flow. In 9 of the 11 healthy subjects and 2 patients with suspected vasculitis and documented Raynaud’s phenomenon, respectively, balanced SSFP imaging coupled with the new FSD scheme was compared with spatial-resolution-matched (0.94 × 0.94 × 0.94 mm3) contrast-enhanced (CE) MRA (0.15 mmol/kg gadopentetate dimeglumine) in terms of overall image quality, venous contamination, motion degradation, and arterial conspicuity. Results The proposed FSD scheme was able to suppress two-dimensional flow signal in the flow phantom and hands and yielded significantly higher arterial conspicuity scores than the conventional scheme did on NC-MRA at the regions of common digitals and proper digitals. Compared with CE-MRA, the refined NC-MRA technique yielded comparable overall image quality and motion degradation, significantly less venous contamination, and significantly higher arterial conspicuity score at digital arteries. Conclusion The FSD-based NC-MRA technique is improved in the depiction of multi-directional flow by applying a two-module FSD preparation, which enhances its potential to serve as an alternative MR angiography technique for the assessment of hand vascular abnormalities. PMID:21487301

  12. 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.

  13. 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

  14. Sub-piexl methods for improving vector quality in echo PIV flow, imaging technology.

    PubMed

    Niu, Lili; Wang, Jing; Qian, Ming; Zheng, Hairong

    2009-01-01

    Developments of many cardiovascular problems have been shown to have a close relationship with arterial flow conditions. An ultrasound-based particle image velocimetry technique(Echo PIV) was recently developed to measure multi-component velocity vectors and local shear rates in arteries and opaque fluid flows by identifying and tracking flow tracers (ultrasound contrast microbubbles) within these flow fields. To improve the measurement accuracy, sub-pixel calculation method was adopted in this paper to maximize the ultrasound RF signal and B mode image correlation accuracy and increase the image spatial resolution. This algorithm is employed in processing both computer-generated particle image patterns and the B-mode images of microbubbles in rotating flows obtained by a high frame rate (up to 1000 frames per second) ultrasound imaging system. The results show the correlation of particle patterns and individual flow vector quality are improved and the overall flow mappings are also improved significantly. This would help the Echo PIV system to provide better multi-component velocity accuracy. PMID:19963463

  15. 2-D arterial wall motion imaging using ultrafast ultrasound and transverse oscillations.

    PubMed

    Salles, Sebastien; Chee, Adrian J Y; Garcia, Damien; Yu, Alfred C H; Vray, Didier; Liebgott, Herve

    2015-06-01

    Ultrafast ultrasound is a promising imaging modality that enabled, inter alia, the development of pulse wave imaging and the local velocity estimation of the so-called pulse wave for a quantitative evaluation of arterial stiffness. However, this technique only focuses on the propagation of the axial displacement of the artery wall, and most techniques are not specific to the intima-media complex and do not take into account the longitudinal motion of this complex. Within this perspective, this paper presents a study of two-dimensional tissue motion estimation in ultrafast imaging combining transverse oscillations, which can improve motion estimation in the transverse direction, i.e., perpendicular to the beam axis, and a phase-based motion estimation. First, the method was validated in simulation. Two-dimensional motion, inspired from a real data set acquired on a human carotid artery, was applied to a numerical phantom to produce a simulation data set. The estimated motion showed axial and lateral mean errors of 4.2 ± 3.4 μm and 9.9 ± 7.9 μm, respectively. Afterward, experimental results were obtained on three artery phantoms with different wall stiffnesses. In this study, the vessel phantoms did not contain a pure longitudinal displacement. The longitudinal displacements were induced by the axial force produced by the wall's axial dilatation. This paper shows that the approach presented is able to perform 2-D tissue motion estimation very accurately even if the displacement values are very small and even in the lateral direction, making it possible to estimate the pulse wave velocity in both the axial and longitudinal directions. This demonstrates the method's potential to estimate the velocity of purely longitudinal waves propagating in the longitudinal direction. Finally, the stiffnesses of the three vessel phantom walls investigated were estimated with an average relative error of 2.2%. PMID:26067039

  16. 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.

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

    PubMed

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

    2013-10-15

    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

  18. 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

  19. Imaging Arterial Fibres Using Diffusion Tensor Imaging—Feasibility Study and Preliminary Results

    NASA Astrophysics Data System (ADS)

    Flamini, Vittoria; Kerskens, Christian; Moerman, Kevin M.; Simms, Ciaran K.; Lally, Caitríona

    2010-12-01

    MR diffusion tensor imaging (DTI) was used to analyze the fibrous structure of aortic tissue. A fresh porcine aorta was imaged at 7T using a spin echo sequence with the following parameters: matrix 128 [InlineEquation not available: see fulltext.] 128 pixel; slice thickness 0.5 mm; interslice spacing 0.1 mm; number of slices 16; echo time 20.3 s; field of view 28 mm [InlineEquation not available: see fulltext.] 28 mm. Eigenvectors from the diffusion tensor images were calculated for the central image slice and the averaged tensors and the eigenvector corresponding to the largest eigenvalue showed two distinct angles corresponding to near [InlineEquation not available: see fulltext.] and [InlineEquation not available: see fulltext.] to the transverse plane of the aorta. Fibre tractography within the aortic volume imaged confirmed that fibre angles were oriented helically with lead angles of [InlineEquation not available: see fulltext.] and [InlineEquation not available: see fulltext.]. The findings correspond to current histological and microscopy data on the fibrous structure of aortic tissue, and therefore the eigenvector maps and fibre tractography appear to reflect the alignment of the fibers in the aorta. In view of current efforts to develop noninvasive diagnostic tools for cardiovascular diseases, DTI may offer a technique to assess the structural properties of arterial tissue and hence any changes or degradation in arterial tissue.

  20. NIKOS II - A System For Non-Invasive Imaging Of Coronary Arteries

    NASA Astrophysics Data System (ADS)

    Dix, Wolf-Rainer; Engelke, Klaus; Heintze, Gerhard; Heuer, Joachim; Graeff, Walter; Kupper, Wolfram; Lohmann, Michael; Makin, I.; Moechel, Thomas; Reumann, Reinhold; Stellmaschek, Karl-Heinz

    1989-05-01

    This paper presents results of the initial in-vivo investigations with the system NIKOS II (NIKOS = Nicht-invasive Koronarangiographie mit Synchrotronstrahlung), an advanced version of NIKOS I which was developed since 1981. Aim of the work is to be able to visualize coronary arteries down to 1mm diameter with an iodine mass density of lmg/cm2, thus allowing non-invasive investigations by intravenous injection of the contrast agent. For this purpose Digital Subtraction Angiography (DSA) in energy subtraction mode (dichromography) is employed. The two images for subtraction are taken at photon energies just below and above the iodine K-edge (33.17keV) After subtraction the background contrast from bone and soft tissue is suppressed and the iodinated structures are strongly enhanced because of the abrupt change of absorption at the K-edge. The two monoenergetic beams are filtered out of a synchrotron radiation beam by a crystal monochromator and measured with a two line detector. One scan (two images) lasts between 250ms (final version) and ls (at present ). The images from the in-vivo investigations of dogs have been promising. The right coronary artery (diameter 1.5mm) was clearly visible. With application of better image processing algorithms the images illustrated in this paper have a definite potential for improvement.

  1. Molecular Imaging Insights into Early Inflammatory Stages of Arterial and Aortic Valve Calcification

    PubMed Central

    New, Sophie E. P.; Aikawa, Elena

    2011-01-01

    Traditional imaging modalities such as computed tomography, although perfectly adept at identifying and quantifying advanced calcification, cannot detect the early stages of this disorder and offer limited insight into the mechanisms of mineral dysregulation. This review presents optical molecular imaging as a promising tool that simultaneously detects pathobiological processes associated with inflammation and early stages of calcification in vivo at the (sub)cellular levels. Research into treatment of cardiovascular calcification is lacking, as shown by clinical trials that have failed to demonstrate the reduction of calcific aortic stenosis. Hence the need to elucidate the pathways that contribute to cardiovascular calcification and to develop new therapeutic strategies to prevent or reverse calcification has driven investigations into the use of molecular imaging. This review discusses studies that have used molecular imaging methods to advance knowledge of cardiovascular calcification, focusing in particular on the inflammation-dependent mechanisms of arterial and aortic valve calcification. PMID:21617135

  2. High bandwidth FASTBUS based data acquisition system for imaging coronary arteries

    SciTech Connect

    Siskind, E.J.; Frost, M.; Morrison, J.; Ong, L.; Reiser, P.; Srinivason, M.

    1983-10-01

    This paper describes the construction of a data acquisition system which will support a minimally invasive replacement for coronary catheterization, generating digitized images of blood flow in the coronary arteries with the aid of a venous injection of x-ray contrast medium. Images generated by a Hamamatsu C1800 TV camera viewing a CGR x-ray image intensifier are digitized by an Analog Devices/Computer Labs MOD-1020/7120 10-bit 20 MHz ADC and then routed to a VICOM model 1500 digital image processing system. Discusses functional specifications and system design. Points out that the FASTBUS system contains three basic items which are interfaced to a single standard FASTBUS crate: a VAX host interface; 64 megabytes of commercial bulk memory; and a DMA controller for moving data from the VICOM into the bulk memory.

  3. Imaging of coronary artery stents using multislice computed tomography: in vitro evaluation.

    PubMed

    Maintz, David; Juergens, Kai-Uwe; Wichter, Thomas; Grude, Matthias; Heindel, Walter; Fischbach, Roman

    2003-04-01

    The aim of this study was to evaluate imaging features of different coronary artery stents during multislice CT Angiography (MSCTA). Nineteen stents made of varying material (steel, nitinol, tantalum) and of varying stent design were implanted in plastic tubes with an inner diameter of 3 mm to simulate a coronary artery. The tubes were filled with iodinated contrast material diluted to 200 Hounsfield units (HU), closed at both ends and positioned in a plastic container filled with oil (-70 HU). The MSCT scans were obtained perpendicular to the stent axes (detector collimation 4x1 mm, table feed 2 mm/rotation, 300 mAs, 120 kV). Axial images and multiplanar reformations were evaluated regarding artifact size, lumen visibility, and intraluminal attenuation values. Artifacts characterized by artifactual thickening of the stent struts leading to apparent reduction in the lumen diameter and increased intraluminal attenuation values were observed in all cases. The stent lumen was totally obscured in the Wiktor stent, the Wallgraft stent, and the Nir Royal stent. Partial residual of the stent lumen could be visualized in all other utilized stent products (artificial lumen reductions ranged from 62% in the V-Flex stent to 94% in the Bx Velocity stent). Parts of the stent lumen can be visualized in most coronary artery stents; however, detectability of in-stent stenoses remains to be evaluated for each stent type. PMID:12664124

  4. 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.

  5. 3D printing of intracranial artery stenosis based on the source images of magnetic resonance angiograph

    PubMed Central

    Liu, Jia; Li, Ming-Li; Sun, Zhao-Yong; Chen, Jie

    2014-01-01

    Background and purpose Three dimensional (3D) printing techniques for brain diseases have not been widely studied. We attempted to ‘print’ the segments of intracranial arteries based on magnetic resonance imaging. Methods Three dimensional magnetic resonance angiography (MRA) was performed on two patients with middle cerebral artery (MCA) stenosis. Using scale-adaptive vascular modeling, 3D vascular models were constructed from the MRA source images. The magnified (ten times) regions of interest (ROI) of the stenotic segments were selected and fabricated by a 3D printer with a resolution of 30 µm. A survey to 8 clinicians was performed to evaluate the accuracy of 3D printing results as compared with MRA findings (4 grades, grade 1: consistent with MRA and provide additional visual information; grade 2: consistent with MRA; grade 3: not consistent with MRA; grade 4: not consistent with MRA and provide probable misleading information). If a 3D printing vessel segment was ideally matched to the MRA findings (grade 2 or 1), a successful 3D printing was defined. Results Seven responders marked “grade 1” to 3D printing results, while one marked “grade 4”. Therefore, 87.5% of the clinicians considered the 3D printing were successful. Conclusions Our pilot study confirms the feasibility of using 3D printing technique in the research field of intracranial artery diseases. Further investigations are warranted to optimize this technique and translate it into clinical practice. PMID:25333049

  6. What do users really perceive: probing the subjective image quality

    NASA Astrophysics Data System (ADS)

    Nyman, Göte; Radun, Jenni; Leisti, Tuomas; Oja, Joni; Ojanen, Harri; Olives, Jean-Luc; Vuori, Tero; Häkkinen, Jukka

    2006-01-01

    Image evaluation schemes must fulfill both objective and subjective requirements. Objective image quality evaluation models are often preferred over subjective quality evaluation, because of their fastness and cost-effectiveness. However, the correlation between subjective and objective estimations is often poor. One of the key reasons for this is that it is not known what image features subjects use when they evaluate image quality. We have studied subjective image quality evaluation in the case of image sharpness. We used an Interpretation-based Quality (IBQ) approach, which combines both qualitative and quantitative approaches to probe the observer's quality experience. Here we examine how naive subjects experienced and classified natural images, whose sharpness was changing. Together the psychometric and qualitative information obtained allows the correlation of quantitative evaluation data with its underlying subjective attribute sets. This offers guidelines to product designers and developers who are responsible for image quality. Combining these methods makes the end-user experience approachable and offers new ways to improve objective image quality evaluation schemes.

  7. Limitations to adaptive optics image quality in rodent eyes

    PubMed Central

    Zhou, Xiaolin; Bedggood, Phillip; Metha, Andrew

    2012-01-01

    Adaptive optics (AO) retinal image quality of rodent eyes is inferior to that of human eyes, despite the promise of greater numerical aperture. This paradox challenges several assumptions commonly made in AO imaging, assumptions which may be invalidated by the very high power and dioptric thickness of the rodent retina. We used optical modeling to compare the performance of rat and human eyes under conditions that tested the validity of these assumptions. Results showed that AO image quality in the human eye is robust to positioning errors of the AO corrector and to differences in imaging depth and wavelength compared to the wavefront beacon. In contrast, image quality in the rat eye declines sharply with each of these manipulations, especially when imaging off-axis. However, some latitude does exist to offset these manipulations against each other to produce good image quality. PMID:22876346

  8. Image quality assessment method in intelligent transportation systems

    NASA Astrophysics Data System (ADS)

    Wang, Bangping; You, Jian; Xiao, Yijun; Wang, Feng

    2007-11-01

    In modern ITS (Intelligent Transportation Systems), the close shot images captured by camera are used to precise recognition of information of vehicles such as VLP (vehicle license plate), VS(vehicle shape) , VBC(vehicle body color) and etc. The precise recognition of vehicle information seriously depends upon quality of images captured by camera. The assessment of image quality is a meaningful work, which can be used to monitor the working state and adjust the control parameters of camera, further more can guide the recognition of information of vehicle. This paper proposes a novel content-based method of assessing images quality for close shot ones in ITS . The method is objective image quality assessment without reference image, which is point to single image. The assessment includes distortion type and distortion amount. Experiments show the method is valid and robust.

  9. 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

  10. Intravascular laser speckle imaging catheter for the mechanical evaluation of the arterial wall

    NASA Astrophysics Data System (ADS)

    Hajjarian, Zeinab; Xi, Jingqun; Jaffer, Farouc A.; Tearney, Guillermo J.; Nadkarni, Seemantini K.

    2011-02-01

    Laser speckle imaging (LSI) is a novel technique for measuring the mechanical properties of atherosclerotic plaques. In LSI, the decorrelation time constant of speckle intensity fluctuations provides an index of viscoelasticity that is closely related to plaque microstructure and composition. Here, we demonstrate for the first time, the feasibility of conducting LSI in vivo using a prototype 1.5 mm (4.5 Fr) diameter intravascular catheter. Investigation of the catheter performance using human arterial samples ex vivo shows that plaque time constants measured by the LSI catheter correlate well with those measured using a free-space bulk optics system. To demonstrate LSI in vivo, the catheter is interfaced with a portable console for intravascular evaluation in the aorta of a living rabbit. Distinct differences in arterial time constants are identified at normal aortic and stented sites in vivo with intravascular LSI.

  11. 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).

  12. Volume of myocardium perfused by coronary artery branches as estimated from 3D micro-CT images of rat hearts

    NASA Astrophysics Data System (ADS)

    Lund, Patricia E.; Naessens, Lauren C.; Seaman, Catherine A.; Reyes, Denise A.; Ritman, Erik L.

    2000-04-01

    Average myocardial perfusion is remarkably consistent throughout the heart wall under resting conditions and the velocity of blood flow is fairly reproducible from artery to artery. Based on these observations, and the fact that flow through an artery is the product of arterial cross-sectional area and blood flow velocity, we would expect the volume of myocardium perfused to be proportional to the cross-sectional area of the coronary artery perfusing that volume of myocardium. This relationship has been confirmed by others in pigs, dogs and humans. To test the body size-dependence of this relationship we used the hearts from rats, 3 through 25 weeks of age. The coronary arteries were infused with radiopaque microfil polymer and the hearts scanned in a micro- CT scanner. Using these 3D images we measured the volume of myocardium and the arterial cross-sectional area of the artery that perfused that volume of myocardium. The average constant of proportionality was found to be 0.15 +/- 0.08 cm3/mm2. Our data showed no statistically different estimates of the constant of proportionality in the rat hearts of different ages nor between the left and right coronary arteries. This constant is smaller than that observed in large animals and humans, but this difference is consistent with the body mass-dependence on metabolic rate.

  13. Molecular Imaging of Bone Marrow Mononuclear Cell Survival and Homing in Murine Peripheral Artery Disease

    PubMed Central

    van der Bogt, Koen E.A.; Hellingman, Alwine A.; Lijkwan, Maarten A.; Bos, Ernst-Jan; de Vries, Margreet R.; Fischbein, Michael P.; Quax, Paul H.; Robbins, Robert C.; Hamming, Jaap F.; Wu, Joseph C.

    2013-01-01

    Introduction Bone marrow mononuclear cell (MNC) therapy is a promising treatment for peripheral artery disease (PAD). This study aims to provide insight into cellular kinetics using molecular imaging following different transplantation methods. Methods and Results MNCs were isolated from F6 transgenic mice (FVB background) that express firefly luciferase (Fluc) and green fluorescence protein (GFP). Male FVB and C57Bl6 mice (n=50) underwent femoral artery ligation and were randomized into 4 groups receiving: (1) single intramuscular (i.m.) injection of 2×106 MNC; (2) four weekly i.m. injections of 5×105 MNC; (3) 2×106 MNCs intravenously (i.v.); and (4) PBS. Cellular kinetics, measured by in vivo bioluminescence imaging (BLI), revealed near-complete donor cell death 4 weeks after i.m. transplantation. Following i.v. transplantation, BLI monitored cells homed in on the injured area in the limb, as well as to the liver, spleen, and bone marrow. Ex vivo BLI showed presence of MNCs in the scar tissue and adductor muscle. However, no significant effects on neovascularisation were observed as monitored by Laser-Doppler-Perfusion-Imaging and histology. Conclusion This is one of the first studies to assess kinetics of transplanted MNCs in PAD using in vivo molecular imaging. MNC survival is short lived and MNCs do not significantly stimulate perfusion in this model. PMID:22239892

  14. Automated classification of patients with coronary artery disease using grayscale features from left ventricle echocardiographic images.

    PubMed

    Acharya, U Rajendra; Sree, S Vinitha; Muthu Rama Krishnan, M; Krishnananda, N; Ranjan, Shetty; Umesh, Pai; Suri, Jasjit S

    2013-12-01

    Coronary Artery Disease (CAD), caused by the buildup of plaque on the inside of the coronary arteries, has a high mortality rate. To efficiently detect this condition from echocardiography images, with lesser inter-observer variability and visual interpretation errors, computer based data mining techniques may be exploited. We have developed and presented one such technique in this paper for the classification of normal and CAD affected cases. A multitude of grayscale features (fractal dimension, entropies based on the higher order spectra, features based on image texture and local binary patterns, and wavelet based features) were extracted from echocardiography images belonging to a huge database of 400 normal cases and 400 CAD patients. Only the features that had good discriminating capability were selected using t-test. Several combinations of the resultant significant features were used to evaluate many supervised classifiers to find the combination that presents a good accuracy. We observed that the Gaussian Mixture Model (GMM) classifier trained with a feature subset made up of nine significant features presented the highest accuracy, sensitivity, specificity, and positive predictive value of 100%. We have also developed a novel, highly discriminative HeartIndex, which is a single number that is calculated from the combination of the features, in order to objectively classify the images from either of the two classes. Such an index allows for an easier implementation of the technique for automated CAD detection in the computers in hospitals and clinics. PMID:23958645

  15. Assessment of single vessel coronary artery disease: results of exercise electrocardiography, thallium-201 myocardial perfusion imaging and radionuclide angiography

    SciTech Connect

    Port, S.C.; Oshima, M.; Ray, G.; McNamee, P.; Schmidt, D.H.

    1985-07-01

    The sensitivity of the commonly used stress tests for the diagnosis of coronary artery disease was analyzed in 46 patients with significant occlusion (greater than or equal to 70% luminal diameter obstruction) of only one major coronary artery and no prior myocardial infarction. In all patients, thallium-201 perfusion imaging (both planar and seven-pinhole tomographic) and 12 lead electrocardiography were performed during the same graded treadmill exercise test and radionuclide angiography was performed during upright bicycle exercise. Exercise rate-pressure (double) product was 22,307 +/- 6,750 on the treadmill compared with 22,995 +/- 5,622 on the bicycle (p = NS). Exercise electrocardiograms were unequivocally abnormal in 24 patients (52%). Qualitative planar thallium images were abnormal in 42 patients (91%). Quantitative analysis of the tomographic thallium images were abnormal in 41 patients (89%). An exercise ejection fraction of less than 0.56 or a new wall motion abnormality was seen in 30 patients (65%). Results were similar for the right (n = 11) and left anterior descending (n = 28) coronary arteries while all tests but the planar thallium imaging showed a lower sensitivity for isolated circumflex artery disease (n = 7). The specificity of the tests was 72, 83, 89 and 72% for electrocardiography, planar thallium imaging, tomographic thallium imaging and radionuclide angiography, respectively. The results suggest that exercise thallium-201 perfusion imaging is the most sensitive noninvasive stress test for the diagnosis of single vessel coronary artery disease.

  16. 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.

  17. 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.

  18. 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.

  19. Time trends of chest pain symptoms and health related quality of life in coronary artery disease

    PubMed Central

    Kiessling, Anna; Henriksson, Peter

    2007-01-01

    Background There is at present a lack of knowledge of time trends in health related quality of life (HRQL) in common patients with coronary artery disease (CAD) treated in ordinary care. The objective of this study is to assess and compare time trends of health related quality of life (HRQL) and chest pain in patients with coronary artery disease. Methods 253 consecutive CAD patients in Stockholm County, Sweden – 197 males/56 females; 60 ± 8 years – were followed during two years. Perceived chest pain symptoms and three global assessments of HRQL were assessed at baseline, after one and after two years. EuroQol-5 dimension (EQ-5D) with a predefined focus on function and symptoms; the broader tapping global estimates of HRQL; EuroQol VAS (EQ-VAS) and Cardiac Health Profile (CHP) were used. Chest pain was ranked according to Canadian Cardiovascular Society (CCS). Change in HRQL was analysed by a repeated measurements ANOVA and chest pain symptoms were analysed by Friedman non-parametric ANOVA. Results Perceived chest pain decreased during the two years (p < 0.00022); CCS 0: 41–51%; CCS 1: 19–15%; CCS 2: 31–27%; CCS 3: 5–4% and CCS 4: 4–2%. By contrast, HRQL did not change: EQ-5D: 0.76 (CI 0.73–0.79) -0.78 (CI 0.75–0.81), EQ-VAS: 0.68 (CI 0.66–0.71)-0.68 (CI 0.65–0.71) and CHP: 0.66 (CI 0.64–0.69) -0.66 (CI 0.64–0.69). Conclusion HRQL did not increase despite a reduction in the severity of chest pain during two years. This implies that the major part of HRQL in these consecutive ordinary patients with CAD is unresponsive to change in chest pain symptoms. PMID:17341296

  20. 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.

  1. New image quality assessment method using wavelet leader pyramids

    NASA Astrophysics Data System (ADS)

    Chen, Xiaolin; Yang, Xiaokang; Zheng, Shibao; Lin, Weiyao; Zhang, Rui; Zhai, Guangtao

    2011-06-01

    In this paper, we propose a wave leader pyramids based Visual Information Fidelity method for image quality assessment. Motivated by the observations that the human vision systems (HVS) are more sensitive to edge and contour regions and that the human visual sensitivity varies with spatial frequency, we first introduce the two-dimensional wavelet leader pyramids to robustly extract the multiscale information of edges. Based on the wavelet leader pyramids, we further propose a visual information fidelity metric to evaluate the quality of images by quantifying the information loss between the original and the distorted images. Experimental results show that our method outperforms many state-of-the-art image quality metrics.

  2. Is image quality a function of contrast perception?

    NASA Astrophysics Data System (ADS)

    Haun, Andrew M.; Peli, Eli

    2013-03-01

    In this retrospective we trace in broad strokes the development of image quality measures based on the study of the early stages of the human visual system (HVS), where contrast encoding is fundamental. We find that while presenters at the Human Vision and Electronic Imaging meetings have frequently strived to find points of contact between the study of human contrast psychophysics and the development of computer vision and image quality algorithms. Progress has not always been made on these terms, although indirect impact of vision science on more recent image quality metrics can be observed.

  3. Application of selective saturation to image the dynamics of arterial blood flow during brain activation using magnetic resonance imaging.

    PubMed

    Vazquez, Alberto L; Lee, Gregory R; Hernandez-Garcia, Luis; Noll, Douglas C

    2006-04-01

    A saturation-based approach is proposed to image the arterial blood flow signal with temporal resolution of 1 to 2 s and in-plane spatial resolution of a few millimeters. Using a saturation approach to suppress the undesired background stationary signal allows the blood water that enters the slice to be imaged at some specified later time. Since the blood protons that are being imaged are not restricted to the intravascular space, this technique is also sensitive to tissue perfusion signal contributions. The signal uptake characteristics of the saturation method proposed were used to study the different signal contributions as a function of the acquisition parameters. A typical perfusion acquisition (FAIR) was also used for comparison. The proposed method was demonstrated in a functional motor activation experiment and the observed signal changes were smaller than those obtained using the FAIR acquisition. The dynamics of the saturation method and FAIR temporal signal changes were investigated and time constants between 2 and 44 s were estimated. The tissue signal contribution to the saturation method's signal was small over the range of acquisition parameters that sensitized it to the arterial compartment. PMID:16506156

  4. 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

  5. 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.

  6. Image quality assessment for an Intel digital imaging chip set prototype

    NASA Astrophysics Data System (ADS)

    Booth, Lawrence A., Jr.; Austin, Phillip G.; Firsty, Caren; Metz, Werner A.

    1998-12-01

    Image quality assessments for Intel's digital imaging chip set prototype are made using objective and subjective image quality assessment criteria. Objective criteria such as signal to noise ratio, linearity, color error, dynamic range, and resolution are used to provide quantitative metrics for engineering development. Subjective criteria such as mean observer scores derived from single stimulus and paired comparison adjectival ratings provide overall product image quality assessment that are used to determine product acceptability assessments for product marketing analysis. These metrics along with the subjective assessment, serve as development tools which allow the product development team to focus on the critical areas which improve the image quality of the product.

  7. 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.

  8. Image processing system performance prediction and product quality evaluation

    NASA Technical Reports Server (NTRS)

    Stein, E. K.; Hammill, H. B. (Principal Investigator)

    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.

  9. 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.

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

    PubMed Central

    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.

    2012-01-01

    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. PMID:22755704

  11. 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.

  12. 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.

  13. NIKOS II - A System For Non-Invasive Imaging Of Coronary Arteries With Synchrotron Radiation

    NASA Astrophysics Data System (ADS)

    Dix, Wolf-Rainer; Engelke, Klaus; Heuer, Joachim; Graeff, Walter; Kupper, Wolfram; Lohmann, Michael; Makin, I.; Moechel, Thomas; Reumann, Reinhold

    1989-10-01

    Aim of the work is the visualization of coronary arteries down to 1 mm diameter with an iodine mass density of 1 mg/cm , thus allowing non-invasive investigations by intravenous injection of the contrast agent. Digital Subtraction Angiography (DSA) in energy subtraction mode (dichromography) is employed for this purpose. The two images Cor subtraction are taken at photon energies just below and above the iodine K-edge (33.17 keV). After subtraction the background contrast - such as bone and soft tissue - is suppressed and the iodinated structures are strongly enhanced because of the abrupt change of absorption at the edge. The two monoenergetic beams (bandwidth about 250 eV) with high intensity (about 1011 photons/mm /s) are only available if synchrotron radiation is used. In HASYLAB at DESY (Hamburg, FRG) the system NIKOS was developed for dichromography. It consists of six main parts: A wiggler beam line, a monochromator which filters the two 12 cm wide beams out of the white synchrotron radiation beam, a fast scanning device, a fast low-noise two-line detector, a safety system and a computer system. At present, one scan (two images) lasts 1 s. The images from the in-vivo investigations of dogs have been promising. The right coronary artery (diameter 1.5 mm) was clearly visible.

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

    PubMed Central

    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 contrast imaging. PMID:24865208

  15. Fractal analysis for reduced reference image quality assessment.

    PubMed

    Xu, Yong; Liu, Delei; Quan, Yuhui; Le Callet, Patrick

    2015-07-01

    In this paper, multifractal analysis is adapted to reduced-reference image quality assessment (RR-IQA). A novel RR-QA approach is proposed, which measures the difference of spatial arrangement between the reference image and the distorted image in terms of spatial regularity measured by fractal dimension. An image is first expressed in Log-Gabor domain. Then, fractal dimensions are computed on each Log-Gabor subband and concatenated as a feature vector. Finally, the extracted features are pooled as the quality score of the distorted image using l1 distance. Compared with existing approaches, the proposed method measures image quality from the perspective of the spatial distribution of image patterns. The proposed method was evaluated on seven public benchmark data sets. Experimental results have demonstrated the excellent performance of the proposed method in comparison with state-of-the-art approaches. PMID:25794391

  16. A new assessment method for image fusion quality

    NASA Astrophysics Data System (ADS)

    Li, Liu; Jiang, Wanying; Li, Jing; Yuchi, Ming; Ding, Mingyue; Zhang, Xuming

    2013-03-01

    Image fusion quality assessment plays a critically important role in the field of medical imaging. To evaluate image fusion quality effectively, a lot of assessment methods have been proposed. Examples include mutual information (MI), root mean square error (RMSE), and universal image quality index (UIQI). These image fusion assessment methods could not reflect the human visual inspection effectively. To address this problem, we have proposed a novel image fusion assessment method which combines the nonsubsampled contourlet transform (NSCT) with the regional mutual information in this paper. In this proposed method, the source medical images are firstly decomposed into different levels by the NSCT. Then the maximum NSCT coefficients of the decomposed directional images at each level are obtained to compute the regional mutual information (RMI). Finally, multi-channel RMI is computed by the weighted sum of the obtained RMI values at the various levels of NSCT. The advantage of the proposed method lies in the fact that the NSCT can represent image information using multidirections and multi-scales and therefore it conforms to the multi-channel characteristic of human visual system, leading to its outstanding image assessment performance. The experimental results using CT and MRI images demonstrate that the proposed assessment method outperforms such assessment methods as MI and UIQI based measure in evaluating image fusion quality and it can provide consistent results with human visual assessment.

  17. Raman chemical imaging system for food safety and quality inspection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Raman chemical imaging technique combines Raman spectroscopy and digital imaging to visualize composition and structure of a target, and it offers great potential for food safety and quality research. In this study, a laboratory-based Raman chemical imaging platform was designed and developed. The i...

  18. Arm exercise-thallium imaging testing for the detection of coronary artery disease

    SciTech Connect

    Balady, G.J.; Weiner, D.A.; Rothendler, J.A.; Ryan, T.J.

    1987-01-01

    Patients with lower limb impairment are often unable to undergo a standard bicycle or treadmill test for the evaluation of coronary artery disease. To establish an alternative method of testing, 50 subjects (aged 56 +/- 10 years) performed arm ergometry testing in conjunction with myocardial thallium scintigraphy. All underwent coronary angiography; significant coronary artery disease (greater than or equal to 70% stenosis) in at least one vessel was present in 41 (82%) of the 50 patients. Thallium scintigraphy was found to have an 83% sensitivity and 78% specificity for detecting coronary disease, compared with a sensitivity and specificity of 54% (p less than 0.01) and 67% (p = NS), respectively, for exercise electrocardiography. In the subgroup of 23 patients who had no prior myocardial infarction or left bundle branch block and were not taking digitalis, thallium scintigraphy had a sensitivity of 80% versus 50% for exercise electrocardiography. Scintigraphy yielded a sensitivity of 84, 74 and 90% for one, two and three vessel disease, respectively. Noninvasive arm ergometry exercise-thallium imaging testing appears to be reliable and useful and should be considered in the evaluation of coronary artery disease in patients with lower limb impairment.

  19. [Assessment of brain perfusion by arterial spin-labeling MR imaging in qusai-moyamoya disease associated with Graves' disease].

    PubMed

    Hayashi, Hisako; Kawatani, Masao; Ohta, Genrei; Kometani, Hiroshi; Ohshima, Yusei

    2014-07-01

    We report a case of 12-year-old girl with Graves' disease who had presented with deterioration in physical and scholastic performances since 10 years of age. She had an episode of atonic seizure and difficulty in speech. Brain MRI revealed formation of moyamoya vessels and a lesion suggestive of ischemic changes in the left frontal lobe. Because of uncontrollable thyrotoxicosis with anti-thyroid drug, she received a subtotal thyroidectomy. Two months later, she received a shunt operation between left superficial temporal artery and middle cerebral artery. The postoperative arterial spin-labeling MR imaging demonstrated an improvement of brain perfusion in left frontal lobe compared with the preoperative one, and provided comparable results of angiography and acetazolamide-challenged 150-gas PET. Thus, arterial spin-labeling MR imaging seems useful for follow-up evaluation of brain perfusion in qusai-moyamoya disease. PMID:25154228

  20. Serial right ventricle /sup 201/Tl imaging after exercise: relation to anatomy of the right coronary artery

    SciTech Connect

    Brown, K.A.; Boucher, C.A.; Okada, R.D.; Strauss, H.W.; McKusick, K.A.; Pohost, G.M.

    1982-12-01

    The relation of the appearance of the right ventricle on serium /sup 201/Tl myocardial imaging to coronary artery anatomy was examined in 88 consecutive patients undergoing exercise /sup 201/Tl testing and coronary angiography for the evaluation of chest pain. Transient defects in the right ventricle were found in 8 patients. All had high grade (greater than or equal to 90%) stenosis of the proximal right coronary artery. Nonvisualization of right ventricular (RV) activity occurred in 10 patients. Nine of the 10 (90%) had significant (greater than or equal to 50% stenosis) disease of the proximal right coronary artery and 7 (70%) had high grade stenosis. The right ventricle appeared normal in 70 patients. Twenty-nine (41%) of these patients had significant proximal right coronary artery disease. Right ventricular appearance was not affected by the presence or absence of disease of the left anterior descending or left circumflex artery or by the appearance of the left ventricle. Thus, with serial RV thallium-201 myocardial imaging after exercise, we found that (1) RV transient defects suggest the presence of high grade proximal right coronary artery stenosis, (2) non-visualization of RV activity also predicts significant proximal right coronary disease, and (3) the right ventricle frequently appears normal despite proximal right coronary artery disease and therefore this finding does not exclude such disease.

  1. Study on the improvement of overall optical image quality via digital image processing

    NASA Astrophysics Data System (ADS)

    Tsai, Cheng-Mu; Fang, Yi Chin; Lin, Yu Chin

    2008-12-01

    This paper studies the effects of improving overall optical image quality via Digital Image Processing (DIP) and compares the promoted optical image with the non-processed optical image. Seen from the optical system, the improvement of image quality has a great influence on chromatic aberration and monochromatic aberration. However, overall image capture systems-such as cellphones and digital cameras-include not only the basic optical system but also many other factors, such as the electronic circuit system, transducer system, and so forth, whose quality can directly affect the image quality of the whole picture. Therefore, in this thesis Digital Image Processing technology is utilized to improve the overall image. It is shown via experiments that system modulation transfer function (MTF) based on the proposed DIP technology and applied to a comparatively bad optical system can be comparable to, even possibly superior to, the system MTF derived from a good optical system.

  2. Association of Hospital Prices for Coronary Artery Bypass Grafting With Hospital Quality and Reimbursement.

    PubMed

    Giacomino, Bria D; Cram, Peter; Vaughan-Sarrazin, Mary; Zhou, Yunshu; Girotra, Saket

    2016-04-01

    Although prices for medical services are known to vary markedly between hospitals, it remains unknown whether variation in hospital prices is explained by differences in hospital quality or reimbursement from major insurers. We obtained "out-of-pocket" price estimates for coronary artery bypass grafting (CABG) from a random sample of US hospitals for a hypothetical patient without medical insurance. We compared hospital CABG price to (1) "fair price" estimate from Healthcare Bluebook data using each hospital's zip code and (2) Society of Thoracic Surgeons composite CABG quality score and risk-adjusted mortality rate. Of 101 study hospitals, 53 (52.5%) were able to provide a complete price estimate for CABG. The mean price for CABG was $151,271 and ranged from $44,824 to $448,038. Except for geographic census region, which was weakly associated with price, hospital CABG price was not associated with other structural characteristics or CABG volume (p >0.10 for all). Likewise, there was no association between a hospital's price for CABG with average reimbursement from major insurers within the same zip code (ρ = 0.07, p value = 0.6), Society of Thoracic Surgeoncomposite quality score (ρ = 0.08, p value = 0.71), or risk-adjusted CABG mortality (ρ = -0.03 p value = 0.89). In conclusion, the price of CABG varied more than 10-fold across US hospitals. There was no correlation between price information obtained from hospitals and the average reimbursement from major insurers in the same market. We also found no evidence to suggest that hospitals that charge higher prices provide better quality of care. PMID:26993975

  3. Ex-vivo Assessment of Coronary Artery Atherosclerosis by Magnetic Resonance Imaging: Correlation with Histopathology

    PubMed Central

    Gomes, Everli P. S. Gonçalves; Rochitte, Carlos Eduardo; Azevedo, Clerio F.; Lemos, Pedro A.; Gutierrez, Paulo Sampaio; César, Luiz Antonio M.

    2014-01-01

    Introduction: In recent years, high-resolution magnetic resonance imaging (MRI) has emerged as a very promising technique for studying atherosclerotic disease in humans. Aim: In the present study we sought to determine whether MRI allowed for the morphological characterization of the coronary vessel wall and atherosclerotic plaques using histopathological assessment as the reference standard. Methods: The study population consisted of 13 patients who died of acute myocardial infarction and underwent autopsy. The proximal portions of the coronary arteries were excised and were evaluated both by MRI and by histopathology. For each arterial segment, the following parameters were calculated through manual planimetry: 1. total vessel area (TVA); 2. luminal area (LA) and 3. plaque area (PA). Results: A total of 207 coronary artery cross-sections were found to be suitable for analysis by both MRI and histopathology and were included in the final analyses. Both methods demonstrated moderate to good agreement for the quantification of TVA (mean difference = 2.4±2.4 mm2, 95‰ limits of agreement from -2.4 to +7.2 mm2; CCC = 0.69, 95‰ CI from 0.63 to 0.75), LA (mean difference = 0.0±1.7 mm2, 95‰ limits of agreement from -3.3 to + 3.3 mm2; CCC = 0.84, 95‰ CI from 0.80 to 0.88) and PA (mean difference = 2.4±2.4 mm2, 95‰ limits of agreement from -2.3 to + 7.1 mm2; CCC = 0.64, 95‰ CI from 0.58 to 0.71). Conclusion: In this ex vivo experimental model we demonstrated good agreement between coronary artery morphometrical measurements obtained by high-resolution MRI and by histopathology. PMID:24847387

  4. The effect of image sharpness on quantitative eye movement data and on image quality evaluation while viewing natural images

    NASA Astrophysics Data System (ADS)

    Vuori, Tero; Olkkonen, Maria

    2006-01-01

    The aim of the study is to test both customer image quality rating (subjective image quality) and physical measurement of user behavior (eye movements tracking) to find customer satisfaction differences in imaging technologies. Methodological aim is to find out whether eye movements could be quantitatively used in image quality preference studies. In general, we want to map objective or physically measurable image quality to subjective evaluations and eye movement data. We conducted a series of image quality tests, in which the test subjects evaluated image quality while we recorded their eye movements. Results show that eye movement parameters consistently change according to the instructions given to the user, and according to physical image quality, e.g. saccade duration increased with increasing blur. Results indicate that eye movement tracking could be used to differentiate image quality evaluation strategies that the users have. Results also show that eye movements would help mapping between technological and subjective image quality. Furthermore, these results give some empirical emphasis to top-down perception processes in image quality perception and evaluation by showing differences between perceptual processes in situations when cognitive task varies.

  5. Arterial vulnerable plaque characterization using ultrasound-induced thermal strain imaging (TSI).

    PubMed

    Kim, Kang; Huang, Sheng-Wen; Hall, Timothy L; Witte, Russell S; Chenevert, Thomas L; O'Donnell, Matthew

    2008-01-01

    Thermal strain imaging (TSI) is demonstrated in two model systems mimicking two potential clinical applications. First, a custom ultrasound (US) microscope produced high-resolution TSI images of an excised porcine coronary artery. Samples were placed in a temperature-controlled water chamber and scanned transversely and longitudinally. Phase-sensitive, correlation-based speckle tracking was applied to map the spatial distribution of temporal strain across the sample. TSI differentiated fatty tissue from water-based arterial wall and muscle with high contrast and a spatial resolution of 60 microm for a 50-MHz transducer. Both transverse and longitudinal TSI images compared well with B-scans of arterial wall structures, including intima, media, adventitia, and overlying fatty tissue. A second model system was used to test the hypothesis that US can produce the heating pattern required for TSI of internal structures. A 2-D phased array with independent drive electronics was combined with a conventional US scanner (iU22, Philips, Bothell, WA) for these studies. This 513-element array, originally designed for the US therapy, acted as the US heat source. To quantify the temporal strain induced by this system, TSI was performed on a homogeneous rubber phantom. TSI temperature estimates were within 3% error for a 3.2 degrees C temperature rise produced within 2 s using a specially designed beamformer and pulse sequencer. The system was then used to produce TSI scanning of an excised kidney containing an intact piece of fat below the collecting system. These images were validated using an magnetic resonance imaging (MRI) pulse sequence designed for lipid quantification. TSI scans matched well MRI scans and histology both anatomically and quantitatively. Finally, to test the potential of US-induced TSI for a significant clinical problem, images were obtained on an excised canine aorta with fatty tissue inside the lumen. Both longitudinal and transversal TSI agreed well with anatomy. These in vitro results demonstrate the potential of high-resolution US-induced TSI with a small temperature change (<1 degrees C) for plaque characterization. PMID:18232359

  6. 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

  7. Comparison of the astronomical and multimedia image quality criteria

    NASA Astrophysics Data System (ADS)

    Anisimova, Elena; Páta, Petr; Fliegel, Karel; Klíma, Miloš

    2012-06-01

    This paper deals with the criteria definition of image quality in astronomy and their comparison with common multimedia approaches. Astronomical images have typical specific properties - high grayscale bit depth, size, high noise occurrence, sensitivity to point spread function deformation and special processing algorithms. They belong to the class of scientific images as well as medical or similar. Their processing and compression is quite different from the classical approach of multimedia image processing. The new compression algorithm based on JPEG2000 is selected as a distortion source in this paper. Selected image quality criteria (multimedia and optimized for astronomical images) are tested on the set of images from the DEIMOS image database with miscellaneous level of the thermally generated CCD noise. The deformation of the point spread function (PSF) is also measured for chosen compression approach.

  8. 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.

  9. Improvement of image quality by polarization mixing

    NASA Astrophysics Data System (ADS)

    Kasahara, Ryosuke; Itoh, Izumi; Hirai, Hideaki

    2014-03-01

    Information about the polarization of light is valuable because it contains information about the light source illuminating an object, the illumination angle, and the object material. However, polarization information strongly depends on the direction of the light source, and it is difficult to use a polarization image with various recognition algorithms outdoors because the angle of the sun varies. We propose an image enhancement method for utilizing polarization information in many such situations where the light source is not fixed. We take two approaches to overcome this problem. First, we compute an image that is the combination of a polarization image and the corresponding brightness image. Because of the angle of the light source, the polarization contains no information about some scenes. Therefore, it is difficult to use only polarization information in any scene for applications such as object detection. However, if we use a combination of a polarization image and a brightness image, the brightness image can complement the lack of scene information. The second approach is finding features that depend less on the direction of the light source. We propose a method for extracting scene features based on a calculation of the reflection model including polarization effects. A polarization camera that has micro-polarizers on each pixel of the image sensor was built and used for capturing images. We discuss examples that demonstrate the improved visibility of objects by applying our proposed method to, e.g., the visibility of lane markers on wet roads.

  10. SAR image quality using advanced pulse compression noise (APCN)

    NASA Astrophysics Data System (ADS)

    Govoni, Mark A.; Elwell, Ryan A.

    2014-05-01

    This work demonstrates the feasibility of using the advanced pulse compression noise (APCN) radar waveform for synthetic aperture radar (SAR). Using a simple image formation process (IFP), we not only show that we can successfully form images using the APCN waveform, but we grow our understanding of how different combinations of APCN waveforms and side lobe weighting functions impact SAR image quality. In this paper, an analysis is presented that compares the target range point spread function (PSF) for several simulated SAR images.

  11. Evidence Base for Quality Control Activities in Cardiovascular Imaging.

    PubMed

    Eskandari, Mehdi; Kramer, Christopher M; Hecht, Harvey S; Jaber, Wael A; Marwick, Thomas H

    2016-03-01

    Quality control is pervasive in most modern business, but, surprisingly, is in its infancy in medicine in general-and cardiovascular imaging in particular. The increasing awareness of the cost of cardiovascular imaging, matched by a desire to show benefits from imaging to patient outcome, suggests that this deficiency should be reassessed. Demonstration of improved quality has been proposed to require a focus on several domains: laboratory organization, patient selection, image acquisition, image interpretation, and results communication. Improvement in these steps will require adoption of a variety of interventions, including laboratory accreditation, appropriate use criteria, and continuous quality control and enhancements in reporting, but the evidence base for the benefit of interventions on these steps has been sparse. The purpose of this review is to evaluate the current status and future goals of developing the evidence base for these processes in cardiovascular imaging. PMID:26965731

  12. Quality evaluation of digital fundus images through combined measures

    PubMed Central

    Veiga, Diana; Pereira, Carla; Ferreira, Manuel; Gonçalves, Luís; Monteiro, João

    2014-01-01

    Abstract. The evaluation of image quality is an important step before an automatic analysis of retinal images. Several conditions can impair the acquisition of a good image, and minimum image quality requirements should be present to ensure that an automatic or semiautomatic system provides an accurate diagnosis. A method to classify fundus images as low or good quality is presented. The method starts with the detection of regions of uneven illumination and evaluates if the segmented noise masks affect a clinically relevant area (around the macula). Afterwards, focus is evaluated through a fuzzy classifier. An input vector is created extracting three focus features. The system was validated in a large dataset (1454 fundus images), obtained from an online database and an eye clinic and compared with the ratings of three observers. The system performance was close to optimal with an area under the receiver operating characteristic curve of 0.9943. PMID:26158021

  13. Intimal Flaps Detected by Optical Frequency Domain Imaging in the Proximal Segments of Native Coronary Arteries.

    PubMed

    Muramatsu, Takashi; García-García, Hector M; Onuma, Yoshinobu; Zhang, Yao-Jun; Bourantas, Christos V; Diletti, Roberto; Iqbal, Javaid; Radu, Maria D; Ozaki, Yukio; Serruys, Patrick W

    2013-06-15

    Background: The prevalence and clinical sequelae of optical frequency domain imaging (OFDI)-detected intimal flaps caused by vessel trauma or plaque rupture in the proximal native coronary arteries have not been described. Methods and Results: OFDI investigation was performed following stent implantation in patients with ST-segment elevation myocardial infarction (STEMI). We defined a flap-like structure (FS) as a disruption or discontinuation of the endoluminal vessel surface, and classified as actual flap or artifact. FS in the left main stem, or maximally 20mm distal to the guiding catheter in the proximal right coronary artery were assessed. A total of 8,931 frames in 97 patients were analyzed in a frame-by-frame fashion (0.125-mm interval). OFDI identified 8 FS in 7 patients, none of which was evident angiographically. All FS were left untreated because the operators per protocol were blinded to the OFDI images. A total of 5 FS in 5 patients (5.1%) appeared to be actual flaps in which only the intima was involved (mean distance from guiding catheter: 4.8±2.7mm). The remaining 3 FS in 3 patients were artifacts; namely, residual blood and interface light reflectivity. There were no adverse cardiac events during 6-months follow-up. Conclusions: In 5.1% of STEMI patients, post-procedural OFDI identified flaps with minimal involvement of the intima in the proximal coronary arteries. A precise interpretation of FS may help decision making to avoid unnecessary procedures. (Clinical Trial Registration Information: ClinicalTrials.gov identifier: NCT01271361.). PMID:23778184

  14. 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.

  15. 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

  16. Reducing Door‐to‐Puncture Times for Intra‐Arterial Stroke Therapy: A Pilot Quality Improvement Project

    PubMed Central

    Mehta, Brijesh P.; Leslie‐Mazwi, Thabele M.; Chandra, Ronil V.; Bell, Donnie L.; Sun, Chung‐Huan J.; Hirsch, Joshua A.; Rabinov, James D.; Rost, Natalia S.; Schwamm, Lee H.; Goldstein, Joshua N.; Levine, Wilton C.; Gupta, Rishi; Yoo, Albert J.

    2014-01-01

    Background Delays to intra‐arterial therapy (IAT) lead to worse outcomes in stroke patients with proximal occlusions. Little is known regarding the magnitude of, and reasons for, these delays. In a pilot quality improvement (QI) project, we sought to examine and improve our door‐puncture times. Methods and Results For anterior‐circulation stroke patients who underwent IAT, we retrospectively calculated in‐hospital time delays associated with various phases from patient arrival to groin puncture. We formulated and then implemented a process change targeted to the phase with the greatest delay. We examined the impact on time to treatment by comparing the pre‐ and post‐QI cohorts. One hundred forty‐six patients (93 pre‐ vs. 51 post‐QI) were analyzed. In the pre‐QI cohort (ie, sequential process), the greatest delay occurred from imaging to the neurointerventional (NI) suite (“picture‐suite”: median, 62 minutes; interquartile range [IQR], 40 to 82). A QI measure was instituted so that the NI team and anesthesiologist were assembled and the suite set up in parallel with completion of imaging and decision making. The post‐QI (ie, parallel process) median picture‐to‐suite time was 29 minutes (IQR, 21 to 41; P<0.0001). There was a 36‐minute reduction in median door‐to‐puncture time (143 vs. 107 minutes; P<0.0001). Parallel workflow and presentation during work hours were independent predictors of shorter door‐puncture times. Conclusions In‐hospital delays are a major obstacle to timely IAT. A simple approach for achieving substantial time savings is to mobilize the NI and anesthesia teams during patient evaluation and treatment decision making. This parallel workflow resulted in a >30‐minute (25%) reduction in median door‐to‐puncture times. PMID:25389281

  17. Imaging of carotid artery vessel wall edema using T2-weighted cardiovascular magnetic resonance

    PubMed Central

    2014-01-01

    Background Atherothrombosis remains a major health problem in the western world, and carotid atherosclerosis is an important contributor to embolic ischemic strokes. It remains a clinical challenge to identify rupture-prone atherosclerotic plaques before clinical events occur. Inflammation, endothelial injury and angiogenesis are features of vulnerable plaques and may all be associated with plaque edema. Therefore, vessel wall edema, which can be detected by 2D T2-weighted cardiovascular magnetic resonance (CMR), may be used as a dynamic marker of disease activity in the atherosclerotic plaque. However, 2D imaging is limited by low spatial resolution in the slice-select direction compared to 3D imaging techniques. We sought to investigate the ability of novel 3D techniques to detect edema induced in porcine carotid arteries by acute balloon injury compared to conventional 2D T2-weighted black-blood CMR. Methods Edema was induced unilaterally by balloon overstretch injury in the carotid artery of nine pigs. Between one to seven hours (average four hours) post injury, CMR was performed using 2D T2-weighted short-tau inversion recovery (T2-STIR), 3D volumetric isotropic turbo spin echo acquisition (VISTA) and 3D T2 prepared gradient-echo (T2prep-GE). The CMR images were compared in terms of signal-to-noise ratio (SNR) and contrast-to-noise (CNR) ratio. Furthermore, the presence of vessel wall injury was validated macroscopically by means of Evans Blue dye that only enters the injured vessel wall. Results All three imaging sequences classified the carotid arteries correctly compared to Evans Blue and all sequences demonstrated a significant increase in SNR of the injured compared to the non-injured carotid vessel wall (T2-STIR, p = 0.002; VISTA, p = 0.004; and T2prep-GE, p = 0.003). There was no significant difference between sequences regarding SNR and CNR. Conclusion The novel 3D imaging sequences VISTA and T2prep-GE perform comparably to conventional 2D T2-STIR in terms of detecting vessel wall edema. The improved spatial coverage of these 3D sequences may facilitate visualization of vessel wall edema to enable detection and monitoring of vulnerable carotid atherosclerotic plaques. PMID:24593873

  18. Pre- and postoperative magnetic resonance imaging in neonatal arterial switch operation using warm perfusion.

    PubMed

    Durandy, Yves; Rubatti, Marina; Couturier, Roland; Rohnean, Adela

    2011-11-01

    Neurological morbidity is a major concern in pediatric cardiac surgery. Cardiopulmonary bypass is one of the few modifiable factors affecting neurodevelopmental outcome. This study aimed to measure the incidence of abnormalities apparent by magnetic resonance imaging (MRI) after neonatal arterial switch operation using warm surgery. Neonates admitted for transposition of the great arteries underwent pre- and postoperative brain MRI. They were operated on using a warm perfusion method. The data collected included antenatal diagnosis, place of birth, gestational age, total maturation score as described by Childs, weight, cyanosis as assessed by minimal SpO(2) sustained for at least 10 min, balloon atrial septostomy, prostaglandin E1 infusion, need for neonatal intensive care, bypass time, time to extubation, and length of stay in intensive care. All of the MRI results were interpreted by the same senior specialist in pediatric neuroimaging, and lesions were classified as white matter injury, infarct, or hemorrhage. On preoperative exam, nine patients (42%) had one or more lesions, with infarct in four patients, white matter injury in four patients, and hemorrhage in five. We were unable to find any correlation between the data collected and brain injury. On postoperative exam, there was one new infarct, two new cases of white matter injury, and three cases of hemorrhage but no worsening of the preoperative lesions. Based on this initial experience with brain imaging, there is no deleterious effect of warm perfusion and no rationale to postpone surgery in neonates with "subclinical" brain injury. PMID:21995580

  19. Computational modeling of cerebral aneurysms in arterial networks reconstructed from multiple 3D rotational angiography images

    NASA Astrophysics Data System (ADS)

    Castro, Marcelo A.; Putman, Christopher M.; Cebral, Juan R.

    2005-04-01

    Previous patient-specific computational fluid dynamics (CFD) models of cerebral aneurysms constructed from 3D rotational angiography have been limited to aneurysms with a single route of blood flow. However, there are numerous aneurysms that accept blood flow from more than one avenue of flow such as aneurysms in the anterior communicating artery. Although the anatomy of these aneurysms could be visualized with other modalities such as CTA and MRA, cerebral rotational angiography has the highest resolution, and is therefore the preferred modality for vascular CFD modeling. The purpose of this paper is to present a novel methodology to construct personalized CFD models of cerebral aneurysms with multiple feeding vessels from multiple rotational angiography images. The methodology is illustrated with two examples: a model of an anterior communicating artery aneurysm constructed from bilateral rotational angiography images, and a model of the complete circle of Willis of a patient with five cerebral aneurysms. In addition, a sensitivity analysis of the intraaneurysmal flow patterns with respect to mean flow balance in the feeding vessels was performed. It was found that the flow patterns strongly depend on the geometry of the aneurysms and the connected vessels, but less on the changes in the flow balance. These types of models are important for studying the hemodynamics of cerebral aneurysms and further our understanding of the disease progression and rupture, as well as for simulating the effect of surgical and endovascular interventions.

  20. 3D Reconstruction of the Retinal Arterial Tree Using Subject-Specific Fundus Images

    NASA Astrophysics Data System (ADS)

    Liu, D.; Wood, N. B.; Xu, X. Y.; Witt, N.; Hughes, A. D.; Samcg, Thom

    Systemic diseases, such as hypertension and diabetes, are associated with changes in the retinal microvasculature. Although a number of studies have been performed on the quantitative assessment of the geometrical patterns of the retinal vasculature, previous work has been confined to 2 dimensional (2D) analyses. In this paper, we present an approach to obtain a 3D reconstruction of the retinal arteries from a pair of 2D retinal images acquired in vivo. A simple essential matrix based self-calibration approach was employed for the "fundus camera-eye" system. Vessel segmentation was performed using a semi-automatic approach and correspondence between points from different images was calculated. The results of 3D reconstruction show the centreline of retinal vessels and their 3D curvature clearly. Three-dimensional reconstruction of the retinal vessels is feasible and may be useful in future studies of the retinal vasculature in disease.

  1. Image quality assessment using Takagi-Sugeno-Kang fuzzy model

    NASA Astrophysics Data System (ADS)

    Äńordević, Dragana; Kukolj, Dragan; Schelkens, Peter

    2015-03-01

    The main aim of the paper is to present a non-linear image quality assessment model based on a fuzzy logic estimator, namely the Takagi-Sugeno-Kang fuzzy model. This image quality assessment model uses a clustered space of input objective metrics. Main advantages of the introduced quality model are simplicity and understandably of its fuzzy rules. As reference model the polynomial 3 rd order model was chosen. The parameters of the Takagi-Sugeno-Kang fuzzy model are optimized in accordance to the mapping criteria of the selected set of input objective quality measures to the Mean Opinion Score (MOS) scale.

  2. 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.

  3. 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.

  4. Echogenicity based approach to detect, segment and track the common carotid artery in 2D ultrasound images.

    PubMed

    Narayan, Nikhil S; Marziliano, Pina

    2015-08-01

    Automatic detection and segmentation of the common carotid artery in transverse ultrasound (US) images of the thyroid gland play a vital role in the success of US guided intervention procedures. We propose in this paper a novel method to accurately detect, segment and track the carotid in 2D and 2D+t US images of the thyroid gland using concepts based on tissue echogenicity and ultrasound image formation. We first segment the hypoechoic anatomical regions of interest using local phase and energy in the input image. We then make use of a Hessian based blob like analysis to detect the carotid within the segmented hypoechoic regions. The carotid artery is segmented by making use of least squares ellipse fit for the edge points around the detected carotid candidate. Experiments performed on a multivendor dataset of 41 images show that the proposed algorithm can segment the carotid artery with high sensitivity (99.6 ±m 0.2%) and specificity (92.9 ±m 0.1%). Further experiments on a public database containing 971 images of the carotid artery showed that the proposed algorithm can achieve a detection accuracy of 95.2% with a 2% increase in performance when compared to the state-of-the-art method. PMID:26736920

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

    PubMed Central

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

    2012-01-01

    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 (OsO4) solution. As a tissue-staining contrast agent, OsO4 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 OsO4 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?/?) mice at 10 ?m resolution. The results show that walls of coronary arteries as small as 45 ?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 OsO4 and micro-CT permits the visualization of the coronary artery wall in intact mouse hearts. PMID:22360411

  7. Digital Receptor Image Quality Evaluation: Effect of Different Filtration Schemes

    NASA Astrophysics Data System (ADS)

    Murphy, Simon; Christianson, Olav; Amurao, Maxwell; Samei, Ehsan

    2010-04-01

    The International Electrotechnical Commission provides a standard measurement methodology to provide performance intercomparison between imaging systems. Its formalism specifies beam quality based on half value layer attained by target kVp and additional Al filtration. Similar beam quality may be attained more conveniently using a filtration combination of Cu and Al. This study aimed to compare the two filtration schemes by their effects on image quality in terms of signal-difference-to-noise ratio, spatial resolution, exposure index, noise power spectrum, modulation transfer function, and detective quantum efficiency. A comparative assessment of the images was performed by analyzing commercially available image quality assessment phantom and by following the IEC 62220-3 formalism.

  8. Figure of Image Quality and Information Capacity in Digital Mammography

    PubMed Central

    Michail, Christos M.; Kalyvas, Nektarios E.; Valais, Ioannis G.; Fudos, Ioannis P.; Fountos, George P.; Dimitropoulos, Nikos; Kandarakis, Ioannis S.

    2014-01-01

    Objectives. In this work, a simple technique to assess the image quality characteristics of the postprocessed image is developed and an easy to use figure of image quality (FIQ) is introduced. This FIQ characterizes images in terms of resolution and noise. In addition information capacity, defined within the context of Shannon's information theory, was used as an overall image quality index. Materials and Methods. A digital mammographic image was postprocessed with three digital filters. Resolution and noise were calculated via the Modulation Transfer Function (MTF), the coefficient of variation, and the figure of image quality. In addition, frequency dependent parameters such as the noise power spectrum (NPS) and noise equivalent quanta (NEQ) were estimated and used to assess information capacity. Results. FIQs for the “raw image” data and the image processed with the “sharpen edges” filter were found 907.3 and 1906.1, correspondingly. The information capacity values were 60.86 × 103 and 78.96 × 103 bits/mm2. Conclusion. It was found that, after the application of the postprocessing techniques (even commercial nondedicated software) on the raw digital mammograms, MTF, NPS, and NEQ are improved for medium to high spatial frequencies leading to resolving smaller structures in the final image. PMID:24895593

  9. Characterization of Hemodynamics in Great Arteries of Wild-Type Mouse Using Computational Fluid Dynamics Based on Ultrasound Images.

    PubMed

    Chen, Zhuo; Zhou, Yue; Ma, Youcai; Wang, Jingying; He, Yihua; Li, Zhian

    2016-03-01

    Hemodynamic factors in cardiovascular system are hypothesized to play a significant role in causing structural heart development. It is thus important to improve our understanding of velocity characteristics and parameters. We present such a study on wild-type mouse to characterize the vessel geometry, flow pattern, and wall shear stress in great arteries. Microultrasound imaging for small animals was used to measure blood boundary and velocity of the great arteries. Subsequently, specimens' flow boundary conditions were used for 3-dimensional reconstructions of the great artery and aortic arch dimensions, and blood flow velocity data were input into subject-specific computational fluid dynamics for modeling hemodynamics. Measurement by microultrasound imaging showed that blood velocities in the great artery and aortic arch had strong correlations with vascular sizes, whereas blood pressure had a weak trend in relation to vascular size. Wall shear stress magnitude increased when closer to arterial branches and reduced proximally in the aortic root and distally in the descending aorta, and the parameters were related to the fluid mechanics in branches in some degree. We developed a method to investigate fluid mechanics in mouse arteries, using a combination of microultrasound and computational fluid dynamics, and demonstrated its ability to reveal detailed geometric, kinematic, and fluid mechanics parameters. PMID:26938034

  10. Separation of arteries and veins in the cerebral cortex using physiological oscillations by optical imaging of intrinsic signal.

    PubMed

    Hu, Dewen; Wang, Yucheng; Liu, Yadong; Li, Ming; Liu, Fayi

    2010-01-01

    An automated method is presented for artery-vein separation in cerebral cortical images recorded with optical imaging of the intrinsic signal. The vessel-type separation method is based on the fact that the spectral distribution of intrinsic physiological oscillations varies from arterial regions to venous regions. In arterial regions, the spectral power is higher in the heartbeat frequency (HF), whereas in venous regions, the spectral power is higher in the respiration frequency (RF). The separation method was begun by extracting the vascular network and its centerline. Then the spectra of the optical intrinsic signals were estimated by the multitaper method. A standard F-test was performed on each discrete frequency point to test the statistical significance at the given level. Four periodic physiological oscillations were examined: HF, RF, and two other eigenfrequencies termed F1 and F2. The separation of arteries and veins was implemented with the fuzzy c-means clustering method and the region-growing approach by utilizing the spectral amplitudes and power-ratio values of the four eigenfrequencies on the vasculature. Subsequently, independent spectral distributions in the arteries, veins, and capillary bed were estimated for comparison, which showed that the spectral distributions of the intrinsic signals were very distinct between the arterial and venous regions. PMID:20615027

  11. 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

  12. Comparison of the Postprocedural Quality of Life between Coronary Artery Bypass Graft Surgery and Percutaneous Coronary Intervention: A Systematic Review

    PubMed Central

    Fatima, Kaneez; Yousuf-ul-Islam, Mohammad; Bawany, Faizan Imran; Khetpal, Akash; Khetpal, Neelam; Lashari, Muhammad Nawaz; Arshad, Mohammad Hussham; Amir, Raamish Bin; Kakalia, Hoshang Rustom; Zaidi, Qaiser Hasan; Mian, Sharmeen Kamran; Kazani, Bahram

    2016-01-01

    The treatment of choice between coronary artery bypass graft surgery (CABG) and percutaneous coronary intervention (PCI) has remained unclear. Considering quality of life (QOL) increases life expectancy, we believe QOL should be important in determining the optimum treatment. Thus the objective of this review was to illustrate the comparative effects of CABG and PCI on postprocedural QOL. Methods. We searched PubMed (Medline) and Embase from inception of the databases to May 2014 using “PCI versus CABG quality of life”, “Percutaneous Coronary intervention versus Coronary artery bypass graft surgery Quality of life”, “PCI versus CABG health status”, “Angioplasty versus CABG”, “Percutaneous coronary intervention versus coronary artery bypass surgery health status”, and different combinations of the above terms. 447 articles were found. After applying strict exclusion criteria, we included 13 studies in this review. Results. From the 9 studies that compared QOL scores at 6 months after procedure, 5 studies reported CABG to be superior. From the 10 studies that compared QOL among patients at 1 year after procedure, 9 reported CABG to be superior. Conclusion. It can be established that CABG is superior to PCI in improving patient's QOL with respect to all scales used to determine quality of life. PMID:26989556

  13. Contrast vs noise effects on image quality

    NASA Astrophysics Data System (ADS)

    Hadar, Ofer; Corse, N.; Rotman, Stanley R.; Kopeika, Norman S.

    1996-11-01

    Low noise images are contract-limited, and image restoration techniques can improve resolution significantly. However, as noise level increases, resolution improvements via image processing become more limited because image restoration increases noise. This research attempts to construct a reliable quantitative means of characterizing the perceptual difference between target and background. A method is suggested for evaluating the extent to which it is possible to discriminate an object which has merged with its surroundings, in noise-limited and contrast limited images, i.e., how hard it would be for an observer to recognize the object against various backgrounds as a function of noise level. The suggested model will be a first order model to begin with, using a regular bar-chart with additive uncorrelated Gaussian noise degraded by standard atmospheric blurring filters. The second phase will comprise a model dealing with higher-order images. This computational model relates the detectability or distinctness of the object to measurable parameters. It also must characterize human perceptual response, i.e. the model must develop metrics which are highly correlated to the ease or difficulty which the human observer experiences in discerning the target from its background. This requirement can be fulfilled only by conducting psychophysical experiments quantitatively comparing the perceptual evaluations of the observers with the results of the mathematical model.

  14. Comparison of cardiac and pulmonary-specific quality of life measures in pulmonary arterial hypertension

    PubMed Central

    Chen, Hubert; De Marco, Teresa; Kobashigawa, Erin A.; Katz, Patricia P.; Chang, Vivian W.; Blanc, Paul D.

    2011-01-01

    Studies systematically comparing the performance of health-related quality-of-life (HRQL) instruments in pulmonary arterial hypertension (PAH) are lacking. We sought to address this gap by comparing cardiac and respiratory-specific measures of HRQL in PAH. We prospectively assessed HRQL in 128 patients with catheterization-confirmed PAH at baseline and at 6, 12, and 24+ months. Cardiac-specific HRQL was assessed using the Minnesota Living with Heart Failure Questionnaire (LHFQ); respiratory-specific HRQL using the Airways Questionnaire 20 (AQ20); and general health status using the 36-item Short Form physical component summary (SF-36 PCS). The LHFQ and AQ20 were highly intercorrelated. Both demonstrated strong internal consistency and converged with the SF-36 PCS. Both discriminated among patients based on World Health Organization functional class (FC), 6-minute walk distance (6MWD), and Borg Dyspnea Index (BDI), except for a potential floor effect associated with low 6MWD. The LHFQ was more responsive than the AQ20 to changes over time in FC, 6MWD, and BDI. In multivariate analyses, the LHFQ and AQ20 were each longitudinal predictors of general health status, independent of FC, 6MWD and BDI. In conclusion, both cardiac-specific and respiratory-specific measures appropriately assess HRQL in most patients with PAH. Overall, the LHFQ demonstrates stronger performance characteristics than the AQ20. PMID:21273391

  15. 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.

  16. Applying image quality in cell phone cameras: lens distortion

    NASA Astrophysics Data System (ADS)

    Baxter, Donald; Goma, Sergio R.; Aleksic, Milivoje

    2009-01-01

    This paper describes the framework used in one of the pilot studies run under the I3A CPIQ initiative to quantify overall image quality in cell-phone cameras. The framework is based on a multivariate formalism which tries to predict overall image quality from individual image quality attributes and was validated in a CPIQ pilot program. The pilot study focuses on image quality distortions introduced in the optical path of a cell-phone camera, which may or may not be corrected in the image processing path. The assumption is that the captured image used is JPEG compressed and the cellphone camera is set to 'auto' mode. As the used framework requires that the individual attributes to be relatively perceptually orthogonal, in the pilot study, the attributes used are lens geometric distortion (LGD) and lateral chromatic aberrations (LCA). The goal of this paper is to present the framework of this pilot project starting with the definition of the individual attributes, up to their quantification in JNDs of quality, a requirement of the multivariate formalism, therefore both objective and subjective evaluations were used. A major distinction in the objective part from the 'DSC imaging world' is that the LCA/LGD distortions found in cell-phone cameras, rarely exhibit radial behavior, therefore a radial mapping/modeling cannot be used in this case.

  17. Imaging quality analysis of multi-channel scanning radiometer

    NASA Astrophysics Data System (ADS)

    Fan, Hong; Xu, Wujun; Wang, Chengliang

    2008-03-01

    Multi-channel scanning radiometer, on boarding FY-2 geostationary meteorological satellite, plays a key role in remote sensing because of its wide field of view and continuous multi-spectral images acquirements. It is significant to evaluate image quality after performance parameters of the imaging system are validated. Several methods of evaluating imaging quality are discussed. Of these methods, the most fundamental is the MTF. The MTF of photoelectric scanning remote instrument, in the scanning direction, is the multiplication of optics transfer function (OTF), detector transfer function (DTF) and electronics transfer function (ETF). For image motion compensation, moving speed of scanning mirror should be considered. The optical MTF measurement is performed in both the EAST/WEST and NORTH/SOUTH direction, whose values are used for alignment purposes and are used to determine the general health of the instrument during integration and testing. Imaging systems cannot perfectly reproduce what they see and end up "blurring" the image. Many parts of the imaging system can cause blurring. Among these are the optical elements, the sampling of the detector itself, post-processing, or the earth's atmosphere for systems that image through it. Through theory calculation and actual measurement, it is proved that DTF and ETF are the main factors of system MTF and the imaging quality can satisfy the requirement of instrument design.

  18. Virtual arterial blood pressure feedback improves chest compression quality during simulated resuscitation?

    PubMed Central

    Rieke, Horst; Rieke, Martin; Gado, Samkon K.; Nietert, Paul J.; Field, Larry C.; Clark, Carlee A.; Furse, Cory M.; McEvoy, Matthew D.

    2014-01-01

    Introduction Quality chest compressions (CC) are the most important factor in successful cardiopulmonary resuscitation. Adjustment of CC based upon an invasive arterial blood pressure (ABP) display would be theoretically beneficial. Additionally, having one compressor present for longer than a 2-min cycle with an ABP display may allow for a learning process to further maximize CC. Accordingly, we tested the hypothesis that CC can be improved with a real-time display of invasively measured blood pressure and with an unchanged, physically fit compressor. Methods A manikin was attached to an ABP display derived from a hemodynamic model responding to parameters of CC rate, depth, and compression-decompression ratio. The area under the blood pressure curve over time (AUC) was used for data analysis. Each participant (N = 20) performed 4 CPR sessions: (1) No ABP display, exchange of compressor every 2 min; (2) ABP display, exchange of compressor every 2 min; (3) no ABP display, no exchange of the compressor; (4) ABP display, no exchange of the compressor. Data were analyzed by ANOVA. Significance was set at a p-value < 0.05. Results The average AUC for cycles without ABP display was 5201 mmHg s (95% confidence interval (CI) of 48045597 mmHg s), and for cycles with ABP display 6110 mmHg s (95% CI of 57156507 mmHg s) (p< 0.0001). The average AUC increase with ABP display for each participant was 20.2 17.4% 95 CI (p < 0.0001). Conclusions Our study confirms the hypothesis that a real-time display of simulated ABP during CPR that responds to participant performance improves achieved and sustained ABP. However, without any real-time visual feedback, even fit compressors demonstrated degradation of CC quality. PMID:23816900

  19. Virtual arterial blood pressure feedback improves chest compression quality during simulated resuscitation.

    TOXLINE Toxicology Bibliographic Information

    Rieke H; Rieke M; Gado SK; Nietert PJ; Field LC; Clark CA; Furse CM; McEvoy MD

    2013-11-01

    INTRODUCTION: Quality chest compressions (CC) are the most important factor in successful cardiopulmonary resuscitation. Adjustment of CC based upon an invasive arterial blood pressure (ABP) display would be theoretically beneficial. Additionally, having one compressor present for longer than a 2-min cycle with an ABP display may allow for a learning process to further maximize CC. Accordingly, we tested the hypothesis that CC can be improved with a real-time display of invasively measured blood pressure and with an unchanged, physically fit compressor.METHODS: A manikin was attached to an ABP display derived from a hemodynamic model responding to parameters of CC rate, depth, and compression-decompression ratio. The area under the blood pressure curve over time (AUC) was used for data analysis. Each participant (N=20) performed 4 CPR sessions: (1) No ABP display, exchange of compressor every 2 min; (2) ABP display, exchange of compressor every 2 min; (3) no ABP display, no exchange of the compressor; (4) ABP display, no exchange of the compressor. Data were analyzed by ANOVA. Significance was set at a p-value<0.05.RESULTS: The average AUC for cycles without ABP display was 5201 mm Hgs (95% confidence interval (CI) of 4804-5597 mm Hgs), and for cycles with ABP display 6110 mm Hgs (95% CI of 5715-6507 mm Hgs) (p<0.0001). The average AUC increase with ABP display for each participant was 20.217.4% 95 CI (p<0.0001).CONCLUSIONS: Our study confirms the hypothesis that a real-time display of simulated ABP during CPR that responds to participant performance improves achieved and sustained ABP. However, without any real-time visual feedback, even fit compressors demonstrated degradation of CC quality.

  20. 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.

  1. 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...

  2. 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.

  3. 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.

  4. 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

  5. Comparative evaluation of image quality from three CT simulation scanners.

    PubMed

    McCann, Claire; Alasti, Hamideh

    2004-01-01

    Today, radiation therapy (RT) is moving toward increased radiation dose to the tumor as a result of 3D conformal RT (3DCRT) and intensity-modulated RT (IMRT), which have been made possible by advances in volumetric-based image planning with digital imaging systems such as computed tomography (CT). Treatment planning for such RT requires superior CT image quality. Our goal in this study was to evaluate and to compare the image quality of three unique CT simulation scanners available at our center for both single- and multiple-slice helical scanners. These scanners included a conventional 70-cm bore single-slice scanner (Philips Medical Systems), a large 85-cm bore single-slice scanner (Philips Medical Systems), and a 70-cm bore multislice scanner (GE Medical Systems). Image quality was evaluated in terms of image noise, low-contrast detectability (LCD), limiting spatial resolution (modulation transfer function), and slice thickness accuracy in accordance with guidelines set out by the AAPM. A commercially available Catphan phantom was used to characterize image quality for both axial and helical modes of scanning. We found that image quality was generally comparable for all scanners. Limiting spatial resolution and slice thickness accuracy were comparable for all three scanners for both scanning modes. The multislice unit was superior in terms of noise content, resulting in improved visualization of small, low-contrast objects, which is of significant clinical importance, particularly for soft tissue delineation. In addition, the multislice unit optimizes volume coverage speed and longitudinal resolution without compromising image quality, a significant advantage for the radiation oncology environment. PMID:15738921

  6. High pitch, low voltage dual source CT pulmonary angiography: assessment of image quality and diagnostic acceptability with hybrid iterative reconstruction.

    PubMed

    McLaughlin, Patrick D; Liang, T; Homiedan, M; Louis, L J; O'Connell, T W; Krzymyk, Karl; Nicolaou, S; Mayo, J R

    2015-04-01

    Increased use of CT Pulmonary angiography in suspected pulmonary embolism (PE) has driven research to minimize radiation dose while maintaining image quality and diagnostic accuracy. Following institutional review board approval, we performed a retrospective comparison study in patients with suspected PE. Patients were scanned using an ultra high pitch dual source technique (pitch = 2.6) using 120 kV (SVCTPA) (n = 54) or 100 kV (RV-CTPA) (n = 52). SV-CTPA images were reconstructed using filtered back projection (SV-wFBP) and RV-CTPA images were reconstructed using both FBP (RV-wFBP) and Iterative Reconstruction (RV-IR). Comparison of radiation dose, diagnostic ability, subjective image noise, quality, and sharpness, diagnostic agreement, signal to noise (SNR) and contrast to noise ratios (CNR) were performed. Mean effective dose was 2.56 ± 0.19 mSv for the RV protocol compared to 5.36 ± 0.60 mSv for the SV. The RV-CTPA protocol resulted in a mean DLP reduction of 52 % and mean CTDI reduction of 51 %. Pulmonary artery SNR and CNR were significantly higher on RV-IR images than SV-wFBP (p = 0.007, p = 0.003). Mean subjective image noise, quality and sharpness scores did not differ significantly between the SV-wFBP and RVIR images (p > 0.05). Subjective quality scores were significantly better for the RV-IR group compared to the RV-wFBP group (p < 0.001). Agreement between readers for presence or absence of pulmonary emboli on RV-IR images was almost perfect (κ = 0.891, p < 0.001). Iterative reconstruction complements ultra high pitch dual source CTPA examinations acquired using a reduced voltage resulting in higher mean pulmonary artery SNR and CNR when compared to both RV-wFBP and SV-CTPA. PMID:24993583

  7. Quantitative image quality evaluation of MR images using perceptual difference models

    PubMed Central

    Miao, Jun; Huo, Donglai; Wilson, David L.

    2008-01-01

    The authors are using a perceptual difference model (Case-PDM) to quantitatively evaluate image quality of the thousands of test images which can be created when optimizing fast magnetic resonance (MR) imaging strategies and reconstruction techniques. In this validation study, they compared human evaluation of MR images from multiple organs and from multiple image reconstruction algorithms to Case-PDM and similar models. The authors found that Case-PDM compared very favorably to human observers in double-stimulus continuous-quality scale and functional measurement theory studies over a large range of image quality. The Case-PDM threshold for nonperceptible differences in a 2-alternative forced choice study varied with the type of image under study, but was ≈1.1 for diffuse image effects, providing a rule of thumb. Ordering the image quality evaluation models, we found in overall Case-PDM ≈ IDM (Sarnoff Corporation) ≈ SSIM [Wang et al. IEEE Trans. Image Process. 13, 600–612 (2004)] > mean squared error ≈ NR [Wang et al. (2004) (unpublished)] > DCTune (NASA) > IQM (MITRE Corporation). The authors conclude that Case-PDM is very useful in MR image evaluation but that one should probably restrict studies to similar images and similar processing, normally not a limitation in image reconstruction studies. PMID:18649487

  8. Analysis of the Effects of Image Quality on Digital Map Generation from Satellite Images

    NASA Astrophysics Data System (ADS)

    Kim, H.; Kim, D.; Kim, S.; Kim, T.

    2012-07-01

    High resolution satellite images are widely used to produce and update a digital map since they became widely available. It is well known that the accuracy of digital map produced from satellite images is decided largely by the accuracy of geometric modelling. However digital maps are made by a series of photogrammetric workflow. Therefore the accuracy of digital maps are also affected by the quality of satellite images, such as image interpretability. For satellite images, parameters such as Modulation Transfer Function(MTF), Signal to Noise Ratio(SNR) and Ground Sampling Distance(GSD) are used to present images quality. Our previous research stressed that such quality parameters may not represent the quality of image products such as digital maps and that parameters for image interpretability such as Ground Resolved Distance(GRD) and National Imagery Interpretability Rating Scale(NIIRS) need to be considered. In this study, we analyzed the effects of the image quality on accuracy of digital maps produced by satellite images. QuickBird, IKONOS and KOMPSAT-2 imagery were used to analyze as they have similar GSDs. We measured various image quality parameters mentioned above from these images. Then we produced digital maps from the images using a digital photogrammetric workstation. We analyzed the accuracy of the digital maps in terms of their location accuracy and their level of details. Then we compared the correlation between various image quality parameters and the accuracy of digital maps. The results of this study showed that GRD and NIIRS were more critical for map production then GSD, MTF or SNR.

  9. 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

  10. 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.

  11. 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.

  12. Image Quality Evalutation on ALOS/PRISM and AVNIR-2

    NASA Astrophysics Data System (ADS)

    Mukaida, Akira; Imoto, Naritoshi; Tadono, Takeo; Murakami, Hiroshi; Kawamoto, Sachi

    2008-11-01

    Image quality evaluation on ALOS (Advanced Land Observing Satellite) / PRISM (Panchromatic Remote-sensing Instrument for Stereo Mapping) and AVNIR-2 (Advanced Visible and Near Infrared Radiometer 2) has been carried out during operational phase. This is a report on result of evaluation for image quality in terms of MTF (Modulation Transfer Function) and SNR (Signal to Noise Ratio) for both PRISM and AVNIR-2. SNR of PRISM image has been increased following the up dating of radiometric correction and implementation of JPEG noise reduction filter. The result was in range of specification for both sensors.

  13. 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.

  14. Toward optimal color image quality of television display

    NASA Astrophysics Data System (ADS)

    MacDonald, Lindsay W.; Endrikhovski, Sergej N.; Bech, Soren; Jensen, Kaj

    1999-12-01

    A general framework and first experimental results are presented for the `OPTimal IMage Appearance' (OPTIMA) project, which aims to develop a computational model for achieving optimal color appearance of natural images on adaptive CRT television displays. To achieve this goal we considered the perceptual constraints determining quality of displayed images and how they could be quantified. The practical value of the notion of optimal image appearance was translated from the high level of the perceptual constraints into a method for setting the display's parameters at the physical level. In general, the whole framework of quality determination includes: (1) evaluation of perceived quality; (2) evaluation of the individual perceptual attributes; and (3) correlation between the physical measurements, psychometric parameters and the subjective responses. We performed a series of psychophysical experiments, with observers viewing a series of color images on a high-end consumer television display, to investigate the relationships between Overall Image Quality and four quality-related attributes: Brightness Rendering, Chromatic Rendering, Visibility of Details and Overall Naturalness. The results of the experiments presented in this paper suggest that these attributes are highly inter-correlated.

  15. 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.

  16. 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.

  17. Learning Receptive Fields and Quality Lookups for Blind Quality Assessment of Stereoscopic Images.

    PubMed

    Shao, Feng; Lin, Weisi; Wang, Shanshan; Jiang, Gangyi; Yu, Mei; Dai, Qionghai

    2016-03-01

    Blind quality assessment of 3D images encounters more new challenges than its 2D counterparts. In this paper, we propose a blind quality assessment for stereoscopic images by learning the characteristics of receptive fields (RFs) from perspective of dictionary learning, and constructing quality lookups to replace human opinion scores without performance loss. The important feature of the proposed method is that we do not need a large set of samples of distorted stereoscopic images and the corresponding human opinion scores to learn a regression model. To be more specific, in the training phase, we learn local RFs (LRFs) and global RFs (GRFs) from the reference and distorted stereoscopic images, respectively, and construct their corresponding local quality lookups (LQLs) and global quality lookups (GQLs). In the testing phase, blind quality pooling can be easily achieved by searching optimal GRF and LRF indexes from the learnt LQLs and GQLs, and the quality score is obtained by combining the LRF and GRF indexes together. Experimental results on three publicly 3D image quality assessment databases demonstrate that in comparison with the existing methods, the devised algorithm achieves high consistent alignment with subjective assessment. PMID:25872220

  18. 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

  19. Imaging quality assessment of multi-modal miniature microscope.

    PubMed

    Lee, Junwon; Rogers, Jeremy; Descour, Michael; Hsu, Elizabeth; Aaron, Jesse; Sokolov, Konstantin; Richards-Kortum, Rebecca

    2003-06-16

    We are developing a multi-modal miniature microscope (4M device) to image morphology and cytochemistry in vivo and provide better delineation of tumors. The 4M device is designed to be a complete microscope on a chip, including optical, micro-mechanical, and electronic components. It has advantages such as compact size and capability for microscopic-scale imaging. This paper presents an optics-only prototype 4M device, the very first imaging system made of sol-gel material. The microoptics used in the 4M device has a diameter of 1.3 mm. Metrology of the imaging quality assessment of the prototype device is presented. We describe causes of imaging performance degradation in order to improve the fabrication process. We built a multi-modal imaging test-bed to measure first-order properties and to assess the imaging quality of the 4M device. The 4M prototype has a field of view of 290 microm in diameter, a magnification of -3.9, a working distance of 250 microm and a depth of field of 29.6+/-6 microm. We report the modulation transfer function (MTF) of the 4M device as a quantitative metric of imaging quality. Based on the MTF data, we calculated a Strehl ratio of 0.59. In order to investigate the cause of imaging quality degradation, the surface characterization of lenses in 4M devices is measured and reported. We also imaged both polystyrene microspheres similar in size to epithelial cell nuclei and cervical cancer cells. Imaging results indicate that the 4M prototype can resolve cellular detail necessary for detection of precancer. PMID:19466016

  20. 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

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

    PubMed

    Norell, Kristin; Lthn, Klas Brorsson; Bergstrm, 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

  2. 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

  3. Imaging anatomy and variation of vertebral artery and bone structure at craniocervical junction

    PubMed Central

    Lv, Shaomao; Ye, Feng; Lin, Qingchi

    2009-01-01

    The objective of this article is to display the vertebral artery and bone structure at the craniocervical junction (CJVA and C0-1-2) with three-dimensional CT angiography (3DCTA) and identify their anatomic features and variations. Eighty-eight subjects without pathology of vertebral artery (VA) and C0-1-2 were selected from head–neck CTA examination. 3D images were formed with volume rendering (VR) and multiplanar reconstruction (MPR). On the 3D images, CJVA and C0-1-2 were measured, and their variations were observed. CJVA goes along C0-1-2 with five curves, of which three curves are visibly away from C0-1-2, one is 0.0–8.3 mm away at the second curve with 0.0–11.2 mm in width, another is 0.0–9.2 mm away at the fourth with 2.8–14.8 mm and the other is 0.0–6.2 mm away at the fifth. Statistical comparisons show that there is no significant difference in the measurements between left and right, and that the curves become smaller and farther away from C0-1-2 with the increase of age. CJVA is not equal in size, with the biggest in the fourth curve and the smallest in the fifth. Statistical comparison shows the left CJVA is larger than the right in the fifth curve. Variations were found on CJVA in 16 cases and on C1 in 12 cases. The anatomy and variations of CJVA and C0-1-2 are complicated. It is of vital significance to identify their anatomic features in clinical practice. PMID:19288143

  4. Interactive 3D stereoscopic digital-image analysis of the basilar artery bifurcation.

    PubMed

    Zurada, Anna; St Gielecki, Jerzy; Baron, Jan; Zawiliński, Jarosław; Kozłowska, Hanna

    2008-03-01

    The goal of this study was to analyze morphometrical variations of the basilar artery bifurcation (BAB), so that physicians could map out a patients anatomical structure prior to delicate neurosurgical procedures. The CT-angio files of 98 patients ranging from 12 to 78 years of age were retrieved. These files were evaluated using Gradual Angiographic Image Data Analyzer (GAIDA) software, where a new interactive three-dimensional (3D) stereoscopic visualization method was used to reconstruct computer images of the BAB complex. Subsequently the measurements of the BAB angles and BAB distances in relation to the dorsum sellae (DS), posterior clinoid processes (PCPs), and posterior biclinoid plane (PBP) were carried out. The average BAB angle was determined to be 117.7 degrees (30.93 degrees -172.2 degrees ). The three types of BAB were classified as type T with a BAB angle greater than 145 degrees (mean 154.4 degrees ), type Y for an angle being equal or less than 145 degrees but greater than 100 degrees (mean 121.5 degrees ) and type V for angles less than 100 degrees (mean 83.28 degrees ). The mean distances between BAB and DS (9.55 mm), BAB and left PCP (12.97 mm), and BAB and right PCP (13.01 mm), BAB and PBP (2.2 mm) were evaluated. Furthermore, the BAB is of great importance when examining basilar artery aneurysm development, particularly at the point of greatest hemodynamic stress, as well as the BAB distances in relation to the bony landmarks used for different approach methods in neurosurgical procedures. PMID:18266284

  5. 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.

  6. 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.

  7. 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

  8. Multiple-image encryption based on triple interferences for flexibly decrypting high-quality images.

    PubMed

    Li, Wei-Na; Phan, Anh-Hoang; Piao, Mei-Lan; Kim, Nam

    2015-04-10

    We propose a multiple-image encryption (MIE) scheme based on triple interferences for flexibly decrypting high-quality images. Each image is discretionarily deciphered without decrypting a series of other images earlier. Since it does not involve any cascaded encryption orders, the image can be decrypted flexibly by using the novel method. Computer simulation demonstrated that the proposed method's running time is less than approximately 1/4 that of the previous similar MIE method. Moreover, the decrypted image is perfectly correlated with the original image, and due to many phase functions serving as decryption keys, this method is more secure and robust. PMID:25967313

  9. Image science and image-quality research in the Optical Sciences Center

    NASA Astrophysics Data System (ADS)

    Barrett, Harrison H.; Myers, Kyle J.

    2014-09-01

    This paper reviews the history of research into imaging and image quality at the Optical Sciences Center (OSC), with emphasis on the period 1970-1990. The work of various students in the areas of psychophysical studies of human observers of images; mathematical model observers; image simulation and analysis, and the application of these methods to radiology and nuclear medicine is summarized. The rapid progress in computational power, at OSC and elsewhere, which enabled the steady advances in imaging and the emergence of a science of imaging, is also traced. The implications of these advances to ongoing research and the current Image Science curriculum at the College of Optical Sciences are discussed.

  10. Imaging stem cell therapy for the treatment of peripheral arterial disease.

    PubMed

    Ransohoff, Julia D; Wu, Joseph C

    2012-05-01

    Arteriosclerotic cardiovascular diseases are among the leading causes of morbidity and mortality worldwide. Therapeutic angiogenesis aims to treat ischemic myocardial and peripheral tissues by delivery of recombinant proteins, genes, or cells to promote neoangiogenesis. Concerns regarding the safety, side effects, and efficacy of protein and gene transfer studies have led to the development of cell-based therapies as alternative approaches to induce vascular regeneration and to improve function of damaged tissue. Cell-based therapies may be improved by the application of imaging technologies that allow investigators to track the location, engraftment, and survival of the administered cell population. The past decade of investigations has produced promising clinical data regarding cell therapy, but design of trials and evaluation of treatments stand to be improved by emerging insight from imaging studies. Here, we provide an overview of pre-clinical and clinical experience using cell-based therapies to promote vascular regeneration in the treatment of peripheral arterial disease. We also review four major imaging modalities and underscore the importance of in vivo analysis of cell fate for a full understanding of functional outcomes. PMID:22239638

  11. 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.

  12. The influence of software filtering in digital mammography image quality

    NASA Astrophysics Data System (ADS)

    Michail, C.; Spyropoulou, V.; Kalyvas, N.; Valais, I.; Dimitropoulos, N.; Fountos, G.; Kandarakis, I.; Panayiotakis, G.

    2009-05-01

    Breast cancer is one of the most frequently diagnosed cancers among women. Several techniques have been developed to help in the early detection of breast cancer such as conventional and digital x-ray mammography, positron and single-photon emission mammography, etc. A key advantage in digital mammography is that images can be manipulated as simple computer image files. Thus non-dedicated commercially available image manipulation software can be employed to process and store the images. The image processing tools of the Photoshop (CS 2) software usually incorporate digital filters which may be used to reduce image noise, enhance contrast and increase spatial resolution. However, improving an image quality parameter may result in degradation of another. The aim of this work was to investigate the influence of three sharpening filters, named hereafter sharpen, sharpen more and sharpen edges on image resolution and noise. Image resolution was assessed by means of the Modulation Transfer Function (MTF).In conclusion it was found that the correct use of commercial non-dedicated software on digital mammograms may improve some aspects of image quality.

  13. Improving image quality of coarse integral volumetric display

    NASA Astrophysics Data System (ADS)

    Kakeya, Hideki

    2009-02-01

    This paper proposes new techniques to improve image quality of the coarse integral volumetric display. Conventional volumetric displays can achieve natural 3D vision without conflict between binocular convergence and focal accommodation, while they cannot express occlusion or gloss of the objects. Multiview displays can express the latter while it cannot achieve the former. The coarse integral volumetric display can realize both natural 3D vision and expression of occlusion and gloss at the same time. Since real image or virtual image of the display panels are formed in the coarse integral volumetric display, aberration of the image can become severe. Though the author has proposed an optical setup to remove major aberration, further improvement is required to achieve better image quality. In this paper the author proposes DFD for distorted image plane, which can realize natural connections between component images. The proposed method takes into account the distortion of real/virtual image plane and each 3D pixel is drawn on the adjacent two distorted image planes so that the brightness may be in inverse proportion to the distance to each plane. Also the author discusses proper selection of component lens to improve connectivity of image.

  14. Off-pump coronary artery bypass grafting in patients with mirror-imaging dextrocardia.

    PubMed

    Yuan, Xin; Sun, Hansong; Wang, Xianqiang

    2015-08-01

    Dextrocardia requires alterations in techniques during coronary artery bypass graft (CABG) surgery. We report two cases undergoing off-pump coronary artery bypass graft (OPCAB) surgery and discuss techniques for the operative management of these patients. PMID:26059016

  15. Developing Matlab scripts for image analysis and quality assessment

    NASA Astrophysics Data System (ADS)

    Vaiopoulos, A. D.

    2011-11-01

    Image processing is a very helpful tool in many fields of modern sciences that involve digital imaging examination and interpretation. Processed images however, often need to be correlated with the original image, in order to ensure that the resulting image fulfills its purpose. Aside from the visual examination, which is mandatory, image quality indices (such as correlation coefficient, entropy and others) are very useful, when deciding which processed image is the most satisfactory. For this reason, a single program (script) was written in Matlab language, which automatically calculates eight indices by utilizing eight respective functions (independent function scripts). The program was tested in both fused hyperspectral (Hyperion-ALI) and multispectral (ALI, Landsat) imagery and proved to be efficient. Indices were found to be in agreement with visual examination and statistical observations.

  16. 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.

  17. 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

  18. Slider-adjusted softcopy ruler for calibrated image quality assessment

    NASA Astrophysics Data System (ADS)

    Jin, Elaine W.; Keelan, Brian W.

    2010-01-01

    ISO 20462 part 3 standardized the hardcopy quality ruler and a softcopy quality ruler based on a binary sort approach involving paired comparisons. The new softcopy ruler method described here utilizes a slider bar to match the quality of the ruler to that of the test image, which is found to substantially reduce the time required per assessment (30 to 15.5 s), with only a modest loss of precision (standard deviations of 2.5 to 2.9 just noticeable differences). In combination, these metrics implied a 20% improvement in the standard error of the mean achievable in a fixed amount of judging time. Ruler images calibrated against the standard quality scale of ISO 20462 are generated for 21 scenes, at 31 quality levels each, achieved through variation of sharpness, while other attributes are held near their preferred positions. The images are bundled with documentation and a MATLAB source code for a graphical user interface that administers softcopy ruler experiments, and these materials are donated to the International Imaging Industry Association for distribution. In conjunction with a specified large flat panel display, these materials should enable users to conduct softcopy quality ruler experiments with minimum effort, and should reduce the barriers to performing calibrated psychophysical measurements.

  19. 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

  20. Influence of segmented vessel size due to limited imaging resolution on coronary hyperemic flow prediction from arterial crown volume.

    PubMed

    van Horssen, P; van Lier, M G J T B; van den Wijngaard, J P H M; VanBavel, E; Hoefer, I E; Spaan, J A E; Siebes, M

    2016-04-01

    Computational predictions of the functional stenosis severity from coronary imaging data use an allometric scaling law to derive hyperemic blood flow (Q) from coronary arterial volume (V), Q = αV(β) Reliable estimates of α and β are essential for meaningful flow estimations. We hypothesize that the relation between Q and V depends on imaging resolution. In five canine hearts, fluorescent microspheres were injected into the left anterior descending coronary artery during maximal hyperemia. The coronary arteries of the excised heart were filled with fluorescent cast material, frozen, and processed with an imaging cryomicrotome to yield a three-dimensional representation of the coronary arterial network. The effect of limited image resolution was simulated by assessing scaling law parameters from the virtual arterial network at 11 truncation levels ranging from 50 to 1,000 μm segment radius. Mapped microsphere locations were used to derive the corresponding relative Q using a reference truncation level of 200 μm. The scaling law factor α did not change with truncation level, despite considerable intersubject variability. In contrast, the scaling law exponent β decreased from 0.79 to 0.55 with increasing truncation radius and was significantly lower for truncation radii above 500 μm vs. 50 μm (P< 0.05). Hyperemic Q was underestimated for vessel truncation above the reference level. In conclusion, flow-crown volume relations confirmed overall power law behavior; however, this relation depends on the terminal vessel radius that can be visualized. The scaling law exponent β should therefore be adapted to the resolution of the imaging modality. PMID:26825519

  1. 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

  2. Evaluation of image quality in computed radiography based mammography systems

    NASA Astrophysics Data System (ADS)

    Singh, Abhinav; Bhwaria, Vipin; Valentino, Daniel J.

    2011-03-01

    Mammography is the most widely accepted procedure for the early detection of breast cancer and Computed Radiography (CR) is a cost-effective technology for digital mammography. We have demonstrated that CR mammography image quality is viable for Digital Mammography. The image quality of mammograms acquired using Computed Radiography technology was evaluated using the Modulation Transfer Function (MTF), Noise Power Spectrum (NPS) and Detective Quantum Efficiency (DQE). The measurements were made using a 28 kVp beam (RQA M-II) using 2 mm of Al as a filter and a target/filter combination of Mo/Mo. The acquired image bit depth was 16 bits and the pixel pitch for scanning was 50 microns. A Step-Wedge phantom (to measure the Contrast-to-noise ratio (CNR)) and the CDMAM 3.4 Contrast Detail phantom were also used to assess the image quality. The CNR values were observed at varying thickness of PMMA. The CDMAM 3.4 phantom results were plotted and compared to the EUREF acceptable and achievable values. The effect on image quality was measured using the physics metrics. A lower DQE was observed even with a higher MTF. This could be possibly due to a higher noise component present due to the way the scanner was configured. The CDMAM phantom scores demonstrated a contrast-detail comparable to the EUREF values. A cost-effective CR machine was optimized for high-resolution and high-contrast imaging.

  3. Laboratory validation of a sparse aperture image quality model

    NASA Astrophysics Data System (ADS)

    Salvaggio, Philip S.; Schott, John R.; McKeown, Donald M.

    2015-09-01

    The majority of image quality studies in the field of remote sensing have been performed on systems with conventional aperture functions. These systems have well-understood image quality tradeoffs, characterized by the General Image Quality Equation (GIQE). Advanced, next-generation imaging systems present challenges to both post-processing and image quality prediction. Examples include sparse apertures, synthetic apertures, coded apertures and phase elements. As a result of the non-conventional point spread functions of these systems, post-processing becomes a critical step in the imaging process and artifacts arise that are more complicated than simple edge overshoot. Previous research at the Rochester Institute of Technology's Digital Imaging and Remote Sensing Laboratory has resulted in a modeling methodology for sparse and segmented aperture systems, the validation of which will be the focus of this work. This methodology has predicted some unique post-processing artifacts that arise when a sparse aperture system with wavefront error is used over a large (panchromatic) spectral bandpass. Since these artifacts are unique to sparse aperture systems, they have not yet been observed in any real-world data. In this work, a laboratory setup and initial results for a model validation study will be described. Initial results will focus on the validation of spatial frequency response predictions and verification of post-processing artifacts. The goal of this study is to validate the artifact and spatial frequency response predictions of this model. This will allow model predictions to be used in image quality studies, such as aperture design optimization, and the signal-to-noise vs. post-processing artifact tradeoff resulting from choosing a panchromatic vs. multispectral system.

  4. 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

  5. Imaging diagnosis-aortic aneurysm and ureteral obstruction secondary to umbilical artery abscessation in a 5-week-old foal.

    PubMed

    Nogradi, Nora; Magdesian, K Gary; Whitcomb, Mary Beth; Church, Molly; Spriet, Mathieu

    2013-01-01

    A 5-week-old foal was evaluated for fever and hematuria of 3 days duration. Cystoscopy localized the blood to be originating from the left ureter. Abdominal ultrasonography revealed left hydronephrosis, hydroureter, and omphaloarteritis of the left umbilical artery with abscess formation that communicated with an arterial structure. Computed tomography (CT) revealed a large aortic aneurysm within the center of the abscess. An exploratory celiotomy was performed and the infection was nonresectable. The prognosis for life was grave; therefore the colt was euthanized. Necropsy findings confirmed the antemortem diagnosis. Ultrasound and CT imaging in this case provided an accurate antemortem diagnosis. PMID:23496157

  6. MR imaging of middle cerebral artery stenosis and occlusion: Value of MR angiography

    SciTech Connect

    Fujita, Norihiko; Sato, Tadayuki ); Hirabuki, Norio; Fujii, Keiko; Hashimoto, Tsutomu; Miura, Takashi; Kozuka, Takahiro )

    1994-02-01

    To investigate the effectiveness of MR angiography in conjunction with spin-echo imaging for evaluating vascular patency in patients with middle cerebral artery (MCA) stenosis or occlusion. Seven patients with MCA stenosis or occlusion, verified with contrast angiography in five and correlated with transcranial Doppler sonography in two, were examined using two-dimensional and/or three-dimensional time-of-flight MR angiographic techniques as well as conventional spin-echo imaging. Of the seven patients, six demonstrated basal ganglionic and/or cortical infarct in the MCA territory. Except one case with minimal stenosis immediately distal to the MCA origin, all six cases with either severe stenosis or occlusion of the main trunk of the MCA showed the absence of normal flow voids using spin-echo imaging in the sylvian fissure on the affected side. However, it was not possible to discriminate between stenosis and occlusion. Although different mechanisms (i.e., flow-induced spin dephasing for the 2-D technique and progressive spin saturation for the 3-D technique) were predominantly responsible for the loss of signal through the area of stenosis, both the 2-D and 3-D MR angiograms clearly depicted the compromised flow of the MCA: a focal discontinuity with decreased vessel caliber corresponded to stenosis, and nonvisualization of distal MCA branches represented occlusion. Either 2-D or 3-D time-of-flight MR angiography is a useful adjunct to conventional parenchymal spin-echo imaging for evaluating vascular patency in patients with MCA stenosis or occlusion, although it is important to recognize that each technique has a different basis for the loss of signal through the area of stenosis. 13 refs., 4 figs., 1 tab.

  7. 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

  8. Clinical Decision Making With Myocardial Perfusion Imaging in Patients With Known or Suspected Coronary Artery Disease

    PubMed Central

    Cremer, Paul; Hachamovitch, Rory; Tamarappoo, Balaji

    2015-01-01

    Myocardial perfusion imaging (MPI) to diagnose coronary artery disease (CAD) is best performed in patients with intermediate pretest likelihood of disease; unfortunately, pretest likelihood is often overestimated, resulting in the inappropriate use of perfusion imaging. A good functional capacity often predicts low risk, and MPI for diagnosing CAD should be reserved for individuals with poor exercise capacity, abnormal resting electrocardiography, or an intermediate or high probability of CAD. With respect to anatomy-based testing, coronary CT angiography has a good negative predictive value, but stenosis severity correlates poorly with ischemia. Therefore decision making with respect to revascularization may be limited when a purely noninvasive anatomical test is used. Regarding perfusion imaging, the diagnostic accuracies of SPECT, PET, and cardiac magnetic resonance are similar, though fewer studies are available with cardiac magnetic resonance. PET coronary flow reserve may offer a negative predictive value sufficiently high to exclude severe CAD such that patients with mild to moderate reversible perfusion defects can forego invasive angiography. In addition, combined anatomical and perfusion-based imaging may eventually offer a definitive evaluation for diagnosing CAD, even in higher risk patients. Any remarkable findings on single-photon emission computed tomography and PET MPI studies are valuable for prognostication. Furthermore, assessment of myocardial blood flow with PET is particularly powerful for prognostication as it reflects the end result of many processes that lead to atherosclerosis. Decision making with respect to revascularization is limited for cardiac MRI and PET MPI. In contrast, retrospective radionuclide studies have identified an ischemic threshold, but randomized trials are needed. In patients with at least moderately reduced left ventricular systolic function, viable myocardium as assessed by PET or MRI, appears to identify patients who benefit from revascularization, but well-executed randomized trials are lacking. PMID:24948154

  9. LANDSAT 4 image data quality analysis

    NASA Technical Reports Server (NTRS)

    Anuta, P. E.

    1983-01-01

    A comparative analysis of TM and MSS data was completed and the results indicate that there are half as many separable spectral classes in the MSS data than in TM. In addition, the minimum separability between classes was also much less in MSS data. Radiometric data quality was also investigated for the TM by computing power spectrum estimates for dark-level data from Lake Michigan. Two significant coherent noise frequencies were observed, one with a wavelength of 3.12 pixels and the other with a 17 pixel wavelength. The amplitude was small (nominally .6 digital count standard deviation) and the noise appears primarily in Bands 3 and 4. No significant levels were observed in other bands. Scan angle dependent brightness effects were also evaluated.

  10. 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.

  11. 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.

  12. Arterial embolism

    PubMed Central

    Lyaker, Michael R.; Tulman, David B.; Dimitrova, Galina T.; Pin, Richard H.; Papadimos, Thomas J.

    2013-01-01

    Surgical and intensive care patients are at a heightened risk for arterial embolization due to pre-existing conditions such as age, hypercoagulability, cardiac abnormalities and atherosclerotic disease. Most arterial emboli are clots that originate in the heart and travel to distant vascular beds where they cause arterial occlusion, ischemia, and potentially infarction. Other emboli form on the surface of eroded arterial plaque or within its lipid core. Thromboemboli are large clots that dislodge from the surface of athesclerotic lesions and occlude distal arteries causing immediate ischemia. Atheroemboli, which originate from fracturing the lipid core tend to cause a process of organ dysfunction and systemic inflammation, termed cholesterol embolization syndrome. The presentation of arterial emboli depends on the arterial bed that is affected. The most common manifestations are strokes and acute lower limb ischemia. Less frequently, emboli target the upper extremities, mesenteric or renal arteries. Treatment involves rapid diagnosis, which may be aided by precise imaging studies and restoration of blood flow. The type of emboli, duration of presentation, and organ system affected determines the treatment course. Long-term therapy includes supportive medical care, identification of the source of embolism and prevention of additional emboli. Patients who experienced arterial embolism as a result of clots formed in the heart should be anticoagulated. Arterial emboli from atherosclerotic disease of the aorta or other large arteries should prompt treatment to reduce the risk for atherosclerotic progression, such as anti-platelet therapy and the use of statin drugs. The use of anticoagulation and surgical intervention to reduce the risk of arterial embolization from atherosclerotic lesions is still being studied. PMID:23724391

  13. 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.

  14. 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.

  15. The influence of noise on image quality in phase-diverse coherent diffraction imaging

    NASA Astrophysics Data System (ADS)

    Wittler, H. P. A.; van Riessen, G. A.; Jones, M. W. M.

    2016-02-01

    Phase-diverse coherent diffraction imaging provides a route to high sensitivity and resolution with low radiation dose. To take full advantage of this, the characteristics and tolerable limits of measurement noise for high quality images must be understood. In this work we show the artefacts that manifest in images recovered from simulated data with noise of various characteristics in the illumination and diffraction pattern. We explore the limits at which images of acceptable quality can be obtained and suggest qualitative guidelines that would allow for faster data acquisition and minimize radiation dose.

  16. 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.

  17. Quantitative quality control in microarray image processing and data acquisition.

    PubMed

    Wang, X; Ghosh, S; Guo, S W

    2001-08-01

    A new integrated image analysis package with quantitative quality control schemes is described for cDNA microarray technology. The package employs an iterative algorithm that utilizes both intensity characteristics and spatial information of the spots on a microarray image for signal-background segmentation and defines five quality scores for each spot to record irregularities in spot intensity, size and background noise levels. A composite score q(com) is defined based on these individual scores to give an overall assessment of spot quality. Using q(com) we demonstrate that the inherent variability in intensity ratio measurements is closely correlated with spot quality, namely spots with higher quality give less variable measurements and vice versa. In addition, gauging data by q(com) can improve data reliability dramatically and efficiently. We further show that the variability in ratio measurements drops exponentially with increasing q(com) and, for the majority of spots at the high quality end, this improvement is mainly due to an improvement in correlation between the two dyes. Based on these studies, we discuss the potential of quantitative quality control for microarray data and the possibility of filtering and normalizing microarray data using a quality metrics-dependent scheme. PMID:11470890

  18. Are image quality metrics adequate to evaluate the quality of geometric objects?

    NASA Astrophysics Data System (ADS)

    Rogowitz, Bernice E.; Rushmeier, Holly E.

    2001-06-01

    Geometric objects are often represented by many millions of triangles or polygons, which limits the ease with which they can be transmitted and displayed electronically. This has lead to the development of many algorithms for simplifying geometric models, and to the recognition that metrics are required to evaluate their success. The goal is to create computer graphic renderings of the object that do not appear to be degraded to a human observer. The perceptual evaluation of simplified objects is a new topic. One approach has been to sue image-based metrics to predict the perceived degradation of simplified 3D models. Since that 2D images of 3D objects can have significantly different perceived quality, depending on the direction of the illumination, 2D measures of image quality may not adequately capture the perceived quality of 3D objects. To address this question, we conducted experiments in which we explicitly compared the perceived quality of animated 3D objects and their corresponding 2D still image projections. Our results suggest that 2D judgements do not provide a good predictor of 3D image quality, and identify a need to develop 'object quality metrics.'

  19. Application of multidimensional quality measures to reconstructed medical images

    NASA Astrophysics Data System (ADS)

    Eskicioglu, Ahmet M.

    1996-03-01

    Lossy compression drastically reduces the operating costs of digital medical imaging systems by enabling more efficient use of transmission and archival facilities in hospitals and doctor's offices. To be able to develop standards for the application of this technology, reliable tools are needed for measuring the quality of reconstructed images. Among the most common measures presently used, the normalized mean squared error (NMSE) does not provide any information concerning the type of impairment, and receiver operating characteristic (ROC) analyses are expensive and time-consuming. This paper evaluates the performance of three quantitative multidimensional measures for image quality. Mimicking the human visual system, they compute local features, and produce a graphical output. Improved Eskicioglu charts, in particular, are shown to be appropriate tools for characterizing compression losses in reconstructed medical images.

  20. Spontaneous coronary artery dissection in a middle-age woman: percutaneous treatment guided by intracoronary imaging techniques.

    PubMed

    Fineschi, Massimo; D'Ascenzi, Flavio; Sirbu, Vasile; Mondillo, Sergio; Pierli, Carlo

    2014-07-01

    Angiographic diagnosis and treatment of spontaneous coronary artery dissection is challenging. Complementary use of intracoronary imaging can provide information to guide percutaneous treatments, particularly in these challenging settings. Here we report a case of a 52-year-old woman presenting with an anterior ST-segment elevation myocardial infarction caused by a spontaneous, long, and spiral dissection of the left anterior descending artery. Intracoronary imaging allowed us to visualize the entry port of the coronary dissection which was not sealed by the first angio-guided stenting. This case demonstrates that, beyond merely diagnostic information, the intracoronary imaging is able to provide information to guide percutaneous treatments, particularly in challenging settings in which coronary angiography reveals its limitations. PMID:25004000

  1. 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.

  2. 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.

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

    PubMed Central

    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. PMID:20210433

  4. 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.

  5. Determination of pasture quality using airborne hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Pullanagari, R. R.; Kereszturi, G.; Yule, Ian J.; Irwin, M. E.

    2015-10-01

    Pasture quality is a critical determinant which influences animal performance (live weight gain, milk and meat production) and animal health. Assessment of pasture quality is therefore required to assist farmers with grazing planning and management, benchmarking between seasons and years. Traditionally, pasture quality is determined by field sampling which is laborious, expensive and time consuming, and the information is not available in real-time. Hyperspectral remote sensing has potential to accurately quantify biochemical composition of pasture over wide areas in great spatial detail. In this study an airborne imaging spectrometer (AisaFENIX, Specim) was used with a spectral range of 380-2500 nm with 448 spectral bands. A case study of a 600 ha hill country farm in New Zealand is used to illustrate the use of the system. Radiometric and atmospheric corrections, along with automatized georectification of the imagery using Digital Elevation Model (DEM), were applied to the raw images to convert into geocoded reflectance images. Then a multivariate statistical method, partial least squares (PLS), was applied to estimate pasture quality such as crude protein (CP) and metabolisable energy (ME) from canopy reflectance. The results from this study revealed that estimates of CP and ME had a R2 of 0.77 and 0.79, and RMSECV of 2.97 and 0.81 respectively. By utilizing these regression models, spatial maps were created over the imaged area. These pasture quality maps can be used for adopting precision agriculture practices which improves farm profitability and environmental sustainability.

  6. Achieving quality in cardiovascular imaging: proceedings from the American College of Cardiology-Duke University Medical Center Think Tank on Quality in Cardiovascular Imaging.

    PubMed

    Douglas, Pamela; Iskandrian, Ami E; Krumholz, Harlan M; Gillam, Linda; Hendel, Robert; Jollis, James; Peterson, Eric; Chen, Jersey; Masoudi, Frederick; Mohler, Emile; McNamara, Robert L; Patel, Manesh R; Spertus, John

    2006-11-21

    Cardiovascular imaging has enjoyed both rapid technological advances and sustained growth, yet less attention has been focused on quality than in other areas of cardiovascular medicine. To address this deficit, representatives from cardiovascular imaging societies, private payers, government agencies, the medical imaging industry, and experts in quality measurement met, and this report provides an overview of the discussions. A consensus definition of quality in imaging and a convergence of opinion on quality measures across imaging modalities was achieved and are intended to be the start of a process culminating in the development, dissemination, and adoption of quality measures for all cardiovascular imaging modalities. PMID:17113004

  7. Radiation dose and image quality for paediatric interventional cardiology.

    PubMed

    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 microGy/frame when moving from 4 to 20 cm PMMA. For cine, these values range from 2.80 to 161.10 microGy/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. PMID:18612174

  8. 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.

  9. Perceived assessment metrics for visible and infrared color fused image quality without reference image

    NASA Astrophysics Data System (ADS)

    Yu, Xuelian; Chen, Qian; Gu, Guohua; Ren, Jianle; Sui, Xiubao

    2015-02-01

    Designing objective quality assessment of color-fused image is a very demanding and challenging task. We propose four no-reference metrics based on human visual system characteristics for objectively evaluating the quality of false color fusion image. The perceived edge metric (PEM) is defined based on visual perception model and color image gradient similarity between the fused image and the source images. The perceptual contrast metric (PCM) is established associating multi-scale contrast and varying contrast sensitivity filter (CSF) with color components. The linear combination of the standard deviation and mean value over the fused image construct the image colorfulness metric (ICM). The color comfort metric (CCM) is designed by the average saturation and the ratio of pixels with high and low saturation. The qualitative and quantitative experimental results demonstrate that the proposed metrics have a good agreement with subjective perception.

  10. 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

  11. Factors that affect print quality in thermal dye transfer imaging

    NASA Astrophysics Data System (ADS)

    Harrison, Daniel J. P.; McInerney, Elizabeth

    1995-04-01

    Thermal dye transfer (TDT) imaging has established itself as the state- of-the-art process for high quality, continuous tone, nonimpact printing. Imaging quality from this process rivals conventional silver halide photography and exceeds other nonimpact printing technologies. Because this output appears to be virtually indistinguishable from photographic prints, there has been an expectation that all the quality attributes of silver halide photography are embodied in a TDT print. However, there are many significant differences that affect output quality between these two technologies. These differences are primarily in color gamut, print artifacts, Dmin, grain/sharpness, and image stability. The range of colors reproducible by a color, hard copy device, known as its color gamut, is dictated primarily by the image- forming dyes used by the device. The size and shape of a device's gamut is controlled by the spectral density distributions of these image forming dyes, the Dmin of the receiver base, the Dmax of each dye, the amount of light scatter, and the spectral distribution of the viewing illuminant. The spectral density distributions of dyes also have an impact on illuminant sensitivity, which is a predictor of how much the color balance of a print will change with a change in illuminant. By determining and then using characteristic curves for various image- forming dyes, we have been able to calculate and compare the color gamuts and illuminant sensitivity of TDT imaging with other technologies (color monitor and silver halide photography, for example). The differences we have found can have a significant impact on output quality, depending upon the application. Compared to conventional photography, thermal dye transfer prints have traditionally had inferior light stability and resistance to damage from fingerprints. In addition, thermal dye transfer prints have been aggressively attacked by plasticized polyvinyl chloride sheets and folders commonly found in office and home environments. We will describe a major advance in thermal dye transfer imaging technology that greatly improves the image stability position of thermal dye transfer images. This advance is derived from the addition of a thin protective layer onto the final print. To add to customer convenience, the protective layer is integrated into the dye donor ribbon as a 4th patch. The protective layer is laminated to the final print using the thermal print head. TDT print artifacts may also influence the quality of TDT output. These defects can include print head streaks, dust and dirt spots, printer banding, and donor ribbon wrinkling. The origin of these defects will be described.

  12. Value and limitations of segmental analysis of stress thallium myocardial imaging for localization of coronary artery disease

    SciTech Connect

    Rigo, P.; Bailey, I.K.; Griffith, L.S.C.; Pitt, B.; Borow, R.D.; Wagner, H.N.; Becker, L.C.

    1980-05-01

    This study was done to determine the value of thallium-201 myocardial scintigraphic imaging (MSI) for identifying disease in the individual coronary arteries. Segmental analysis of rest and stress MSI was performed in 133 patients with ateriographically proved coronary artery disease (CAD). Certain scintigraphic segments were highly specific (97 to 100%) for the three major coronary arteries: anterior wall and septum for the left anterior descending (LAD) coronary artery; the inferior wall for the right coronary artery (RCA); and the proximal lateral wall for the circumflex (LCX) artery. Perfusion defects located in the anterolateral wall in the anterior view were highly specific for proximal disease in the LAD involving the major diagonal branches, but this was not true for septal defects. The apical segments were not specific for any of the three major vessels. Although MSI was abnormal in 89% of these patients with CAD, it was less sensitive for identifying individual vessel disease: 63% for LAD, 50% for RCA, and 21% for LCX disease (narrowings > = 50%). Sensitivity increased with the severity of stenosis, but even for 100% occlusions was only 87% for LAD, 58% for RCA and 38% for LCX. Sensitivity diminished as the number of vessels involved increased: with single-vessel disease, 80% of LAD, 54% of RAC and 33% of LCX lesions were detected, but in patients with triple-vessel disease, only 50% of LAD, 50% of RCA and 16% of LCX lesions were identified. Thus, although segmented analysis of MSI can identify disease in the individual coronary arteries with high specificity, only moderate sensitivity is achieved, reflecting the tendency of MSI to identify only the most severely ischemic area among several that may be present in a heart. Perfusion scintigrams display relative distributions rather than absolute values for myocardial blood flow.

  13. 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.

  14. 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.

  15. Venous and Arterial Flow Quantification, are Equally Accurate and Precise with Parallel Imaging Compressed Sensing 4D Phase Contrast MRI

    PubMed Central

    Tariq, Umar; Hsiao, Albert; Alley, Marcus; Zhang, Tao; Lustig, Michael; Vasanawala, Shreyas S.

    2012-01-01

    Purpose To evaluate precision and accuracy of parallel-imaging compressed-sensing 4D phase contrast (PICS-4DPC) MRI venous flow quantification in children with patients referred for cardiac MRI at our childrens hospital. Materials and Methods With IRB approval and HIPAA compliance, 22 consecutive patients without shunts underwent 4DPC as part of clinical cardiac MRI examinations. Flow measurements were obtained in the superior and inferior vena cava, ascending and descending aorta and the pulmonary trunk. Conservation of flow to the upper, lower and whole body was used as an internal physiologic control. The arterial and venous flow rates at each location were compared with paired t-tests and F-tests to assess relative accuracy and precision. RESULTS Arterial and venous flow measurements were strongly correlated for the upper (?=0.89), lower (?=0.96) and whole body (?=0.97); net aortic and pulmonary trunk flow rates were also tightly correlated (?=0.97). There was no significant difference in the value or precision of arterial and venous flow measurements in upper, lower or whole body, though there was a trend toward improved precision with lower velocity-encoding settings. Conclusion With PICS-4DPC MRI, the accuracy and precision of venous flow quantification are comparable to that of arterial flow quantification at velocity-encodings appropriate for arterial vessels. PMID:23172846

  16. Automatic plaque characterization and vessel wall segmentation in magnetic resonance images of atherosclerotic carotid arteries

    NASA Astrophysics Data System (ADS)

    Adame, Isabel M.; van der Geest, Rob J.; Wasserman, Bruce A.; Mohamed, Mona; Reiber, Johan H. C.; Lelieveldt, Boudewijn P. F.

    2004-05-01

    Composition and structure of atherosclerotic plaque is a primary focus of cardiovascular research. In vivo MRI provides a meanse to non-invasively image and assess the morphological features of athersclerotic and normal human carotid arteries. To quantitatively assess the vulnerability and the type of plaque, the contours of the lumen, outer boundary of the vessel wall and plaque components, need to be traced. To achieve this goal, we have developed an automated contou detection technique, which consists of three consecutive steps: firstly, the outer boundary of the vessel wall is detected by means of an ellipse-fitting procedure in order to obtain smoothed shapes; secondly, the lumen is segnented using fuzzy clustering. Thre region to be classified is that within the outer vessel wall boundary obtained from the previous step; finally, for plaque detection we follow the same approach as for lumen segmentation: fuzzy clustering. However, plaque is more difficult to segment, as the pixel gray value can differ considerably from one region to another, even when it corresponds to the same type of tissue. That makes further processing necessary. All these three steps might be carried out combining information from different sequences (PD-, T2-, T1-weighted images, pre- and post-contrast), to improve the contour detection. The algorithm has been validated in vivo on 58 high-resolution PD and T1 weighted MR images (19 patients). The results demonstrate excellent correspondence between automatic and manual area measurements: lumen (r=0.94), outer (r=0.92), and acceptable for fibrous cap thickness (r=0.76).

  17. Perceived Image Quality Improvements from the Application of Image Deconvolution to Retinal Images from an Adaptive Optics Fundus Imager

    NASA Astrophysics Data System (ADS)

    Soliz, P.; Nemeth, S. C.; Erry, G. R. G.; Otten, L. J.; Yang, S. Y.

    Aim: The objective of this project was to apply an image restoration methodology based on wavefront measurements obtained with a Shack-Hartmann sensor and evaluating the restored image quality based on medical criteria.Methods: Implementing an adaptive optics (AO) technique, a fundus imager was used to achieve low-order correction to images of the retina. The high-order correction was provided by deconvolution. A Shack-Hartmann wavefront sensor measures aberrations. The wavefront measurement is the basis for activating a deformable mirror. Image restoration to remove remaining aberrations is achieved by direct deconvolution using the point spread function (PSF) or a blind deconvolution. The PSF is estimated using measured wavefront aberrations. Direct application of classical deconvolution methods such as inverse filtering, Wiener filtering or iterative blind deconvolution (IBD) to the AO retinal images obtained from the adaptive optical imaging system is not satisfactory because of the very large image size, dificulty in modeling the system noise, and inaccuracy in PSF estimation. Our approach combines direct and blind deconvolution to exploit available system information, avoid non-convergence, and time-consuming iterative processes. Results: The deconvolution was applied to human subject data and resulting restored images compared by a trained ophthalmic researcher. Qualitative analysis showed significant improvements. Neovascularization can be visualized with the adaptive optics device that cannot be resolved with the standard fundus camera. The individual nerve fiber bundles are easily resolved as are melanin structures in the choroid. Conclusion: This project demonstrated that computer-enhanced, adaptive optic images have greater detail of anatomical and pathological structures.

  18. 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

  19. 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.

  20. High-speed terahertz imaging toward food quality inspection.

    PubMed

    Ok, Gyeongsik; Park, Kisang; Kim, Hyun Jung; Chun, Hyang Sook; Choi, Sung-Wook

    2014-03-01

    In contrast to conventional x-ray food inspection systems that have difficulty in detecting low-density materials, a terahertz imaging system can even identify insects and plastics embedded in a food matrix. A reflection-mode continuous-wave terahertz imaging system was therefore developed for application to food quality inspection, which requires fast, compact, and low-cost detection. High-speed operation of the terahertz imaging system was achieved through the use of a beam-steering tool. A reasonable compromise between the spatial resolution and the scan length of an aspheric f-theta scanning lens could be achieved by optimizing the lens parameters. PMID:24663370

  1. 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.

  2. Impact of atmospheric aerosols on long range image quality

    NASA Astrophysics Data System (ADS)

    LeMaster, Daniel A.; Eismann, Michael T.

    2012-06-01

    Image quality in high altitude long range imaging systems can be severely limited by atmospheric absorption, scattering, and turbulence. Atmospheric aerosols contribute to this problem by scattering target signal out of the optical path and by scattering in unwanted light from the surroundings. Target signal scattering may also lead to image blurring though, in conventional modeling, this effect is ignored. The validity of this choice is tested in this paper by developing an aerosol modulation transfer function (MTF) model for an inhomogeneous atmosphere and then applying it to real-world scenarios using MODTRAN derived scattering parameters. The resulting calculations show that aerosol blurring can be effectively ignored.

  3. Definition on SAR image quality measurements for UWB SAR

    NASA Astrophysics Data System (ADS)

    Vu, Viet T.; Sjögren, Thomas K.; Pettersson, Mats I.; Gustavsson, Anders

    2008-10-01

    Analyses in this study show that measurements under currently used definitions on SAR image quality measurement may be unsuitable for UWB SAR. The main objective of this paper is therefore to propose a definition based on the shape of a single point target in a SAR image which is more suitable for UWB SAR. We use both real and simulated data based on the airborne UWB low frequency SAR CARABAS-II in experiments. The time-domain algorithm Global Backprojection (GBP) is selected for the image formation in this study.

  4. Quality assurance methodology and applications to abdominal imaging PQI.

    PubMed

    Paushter, David M; Thomas, Stephen

    2016-03-01

    Quality assurance has increasingly become an integral part of medicine, with tandem goals of increasing patient safety and procedural quality, improving efficiency, lowering cost, and ultimately improving patient outcomes. This article reviews quality assurance methodology, ranging from the PDSA cycle to the application of lean techniques, aimed at operational efficiency, to continually evaluate and revise the health care environment. Alignment of goals for practices, hospitals, and healthcare organizations is critical, requiring clear objectives, adequate resources, and transparent reporting. In addition, there is a significant role played by regulatory bodies and oversight organizations in determining external benchmarks of quality, practice, and individual certification and reimbursement. Finally, practical application of quality principles to practice improvement projects in abdominal imaging will be presented. PMID:26934893

  5. 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.

  6. DIANE stationary neutron radiography system image quality and industrial applications

    NASA Astrophysics Data System (ADS)

    Cluzeau, S.; Huet, J.; Le Tourneur, P.

    1994-05-01

    The SODERN neutron radiography laboratory has operated since February 1993 using a sealed tube generator (GENIE 46). An experimental programme of characterization (dosimetry, spectroscopy) has confirmed the expected performances concerning: neutron flux intensity, neutron energy range, residual gamma flux. Results are given in a specific report [2]. This paper is devoted to the image performance reporting. ASTM and specific indicators have been used to test the image quality with various converters and films. The corresponding modulation transfer functions are to be determined from image processing. Some industrial applications have demonstrated the capabilities of the system: corrosion detection in aircraft parts, ammunitions filling testing, detection of polymer lacks in sandwich steel sheets, detection of moisture in a probe for geophysics, residual ceramic cores imaging in turbine blades. Various computerized electronic imaging systems will be tested to improve the industrial capabilities.

  7. Measurement of the 3D arterial wall strain tensor using intravascular B-mode ultrasound images: a feasibility study

    NASA Astrophysics Data System (ADS)

    Liang, Yun; Zhu, Hui; Friedman, Morton H.

    2010-11-01

    Intravascular ultrasound (IVUS) elastography is a promising tool for studying atherosclerotic plaque composition and assessing plaque vulnerability. Current IVUS elastography techniques can measure the 1D or 2D strain of the vessel wall using various motion tracking algorithms. Since biological soft tissue tends to deform non-uniformly in 3D, measurement of the complete 3D strain tensor is desirable for more rigorous analysis of arterial wall mechanics. In this paper, we extend our previously developed method of 2D arterial wall strain measurement based on non-rigid image registration into 3D strain measurement. The new technique registers two image volumes acquired from the same vessel segment under different levels of luminal pressure and longitudinal stress. The 3D displacement field obtained from the image registration is used to calculate the local 3D strain tensor. From the 3D strain tensor, radial, circumferential and longitudinal strain distributions can be obtained and displayed. This strain tensor measurement method is validated and evaluated using IVUS images of healthy porcine carotid arteries subjected to a luminal pressure increase and longitudinal stretch. The ability of the algorithm to overcome systematic noise was tested, as well as the consistency of the results under different longitudinal frame resolutions.

  8. 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

  9. Simultaneous analysis and quality assurance for diffusion tensor imaging.

    PubMed

    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

  10. Retinal Image Quality and Postnatal Visual Experience during Infancy

    PubMed Central

    Candy, T. Rowan; Wang, Jingyun; Ravikumar, Sowmya

    2009-01-01

    Studies of animal models have demonstrated that abnormal visual experience can lead to abnormal visual development. The provision of normal optical experience for human infants and children requires an understanding of their typical retinal image quality in the natural dynamic environment. The literature related to this topic is reviewed. PMID:19417704

  11. 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.

  12. An image quality evaluation tool simulating image sensors including quantum efficiency off-axis effect

    NASA Astrophysics Data System (ADS)

    Mornet, Clémence; Vaillant, Jérôme; Decroux, Thomas; Virollet, Nicolas; Herault, Didier; Schanen, Isabelle

    2011-01-01

    The image quality evaluation of CMOS sensors is a big challenge for camera module manufacturers. In this paper, we present an update of the Image Quality Evaluation Tool, a graphical user interface simulating image sensors to assess the performance of a pixel. The simulated images are computed from operating conditions and sensor's characteristics like Quantum Efficiency including off-axis effect. Simulation of QE off-axis impact has been based on characterization data. The method does not require optics, making it suitable for early design phases as for optimizations and investigations. Both measurement and implementation in the tool will be explained. The QE degradation with angle effect will be highlighted on simulated images. A uniform gray scene or coloured image simulation from QE off-axis measurement will help engineers to calculate post-processing digital correction like colour shading correction or colour correction matrix versus pixel position.

  13. In-Situ Characterization of the Uncrimping Process of Arterial Collagen Fibers Using Two-Photon Confocal Microscopy and Digital Image Correlation

    PubMed Central

    Wang, Ruoya; Brewster, Luke P.; Gleason, Rudolph L.

    2015-01-01

    Uncrimping of collagen fibers in the arterial wall is an integral process in modulating the macro-level mechanical response of arteries. Uncrimping of collagen fibers leads to a gradual, but significant strain-stiffening response of the artery at physiological pressures and prevents overdistention at elevated pressures. In this study, we imaged adventitial collagen fibers from a fresh primate artery using two-photon excitation microscopy while subjecting the artery to physiological inflation pressures and axial stretch. The imaging focal plane was fixed at a constant radial location in the adventitial wall by adjusting the focal distance as the artery inflated, allowing for the continuously monitoring of the uncrimping process of a single region of collagen fibers. Digital image correlation was then applied to the sequential images to assess and correlate the local displacements to manual traces of selected reference fibers and their engagements. We found that the collagen fibers of interest became fully engaged at a luminal pressure of 20 mmHg, this was then followed by significant rotation of these fibers as the bulk artery continued to dilate. This technique allows for the development of uncrimping metrics to more accurately characterize the kinematics of collagen fibers under physiological loads, which can aid in the development of more accurate microstructural constitutive models for arteries. PMID:24050510

  14. Evaluating the anatomical location of the posterior superior alveolar artery in cone beam computed tomography images.

    PubMed

    Khojastehpour, L; Dehbozorgi, M; Tabrizi, R; Esfandnia, S

    2016-03-01

    The purpose of this study was to examine the diameter, location, and frequency of the appearance of the posterior superior alveolar artery (PSAA) in preoperative cone beam computed tomography (CBCT) scans. Two hundred and eleven pre-implant CBCT scans were reviewed. The following criteria were considered in all subjects: (1) the location of the artery: intra-sinus or below the membrane (type I), intraosseous (type II), or superficial (type III); (2) the distance between the lower border of the artery and the alveolar crest; (3) the bone height measured from the floor of the sinus to the crest of the ridge; (4) the distance from the lateral wall of the artery to the medial wall of the maxillary sinus; and (5) the diameter of the artery (in millimetres). The distance between the artery and the medial sinus wall, as well as the diameter of the artery, were greater in patients with an alveolar bone height ?10mm than in those with a bone height >10mm. The distance from the artery to the medial sinus wall and the diameter of the artery were positively correlated with the number of missing teeth. It was also found that the diameter of the PSAA increased with increasing age. PMID:26516028

  15. Effects of display rendering on HDR image quality assessment

    NASA Astrophysics Data System (ADS)

    Zerman, Emin; Valenzise, Giuseppe; De Simone, Francesca; Banterle, Francesco; Dufaux, Frederic

    2015-09-01

    High dynamic range (HDR) displays use local backlight modulation to produce both high brightness levels and large contrast ratios. Thus, the display rendering algorithm and its parameters may greatly affect HDR visual experience. In this paper, we analyze the impact of display rendering on perceived quality for a specific display (SIM2 HDR47) and for a popular application scenario, i.e., HDR image compression. To this end, we assess whether significant differences exist between subjective quality of compressed images, when these are displayed using either the built-in rendering of the display, or a rendering algorithm developed by ourselves. As a second contribution of this paper, we investigate whether the possibility to estimate the true pixel-wise luminance emitted by the display, offered by our rendering approach, can improve the performance of HDR objective quality metrics that require true pixel-wise luminance as input.

  16. Techniques to evaluate the quality of medical images

    NASA Astrophysics Data System (ADS)

    Perez-Diaz, Marlen

    2014-11-01

    There is not a perfect agree in the definition of medical image quality from the physician and physicist point of view. The present conference analyzes the standard techniques used to grade image quality. In the first place, an analysis about how viewing conditions related to environment, monitor used or physician experience determines the subjective evaluation is done. After that, the physics point of view is analyzed including the advantage and disadvantage of the main published methods like: Quality Control Tests, Mathematical metrics, Modulation Transfer Function, Noise Power Spectrum, System Response Curve and Mathematical observers. Each method is exemplified with the results of updated papers. We concluded that the most successful methods up to the present have been those which include simulations of the Human Visual System. They have good correlation between the results of the objective metrics and the subjective evaluation made by the observers.

  17. An improved algorithm for femoropopliteal artery centerline restoration using prior knowledge of shapes and image space data.

    PubMed

    Rakshe, Tejas; Fleischmann, Dominik; Rosenberg, Jarrett; Roos, Justus E; Straka, Matus; Napel, Sandy

    2008-07-01

    Accurate arterial centerline extraction is essential for comprehensive visualization in CT Angiography. Time consuming manual tracking is needed when automated methods fail to track centerlines through severely diseased and occluded vessels. A previously described algorithm, Partial Vector Space Projection (PVSP), which uses vessel shape information from a database to bridge occlusions of the femoropopliteal artery, has a limited accuracy in long (>100 mm) occlusions. In this article we introduce a new algorithm, Intermediate Point Detection (IPD), which uses calcifications in the occluded artery to provide additional information about the location of the centerline to facilitate improvement in PVSP performance. It identifies calcified plaque in image space to find the most useful point within the occlusion to improve the estimate from PVSP. In this algorithm candidates for calcified plaque are automatically identified on axial CT slices in a restricted region around the estimate obtained from PVSP. A modified Canny edge detector identifies the edge of the calcified plaque and a convex polygon fit is used to find the edge of the calcification bordering the wall of the vessel. The Hough transform for circles estimates the center of the vessel on the slice, which serves as a candidate intermediate point. Each candidate is characterized by two scores based on radius and relative position within the occluded segment, and a polynomial function is constructed to define a net score representing the potential benefit of using this candidate for improving the centerline. We tested our approach in 44 femoropopliteal artery occlusions of lengths up to 398 mm in 30 patients with peripheral arterial occlusive disease. Centerlines were tracked manually by four-experts, twice each, with their mean serving as the reference standard. All occlusions were first interpolated with PVSP using a database of femoropopliteal arterial shapes obtained from a total of 60 subjects. Occlusions longer than 80 mm (N = 20) were then processed with the IPD algorithm, provided calcifications were found (N = 14). We used the maximum point-wise distance of an interpolated curve from the reference standard as our error metric. The IPD algorithm significantly reduced the average error of the initial PVSP from 2.76 to 1.86 mm (p < 0.01). The error was less than the clinically desirable 3 mm (smallest radius of the femoropopliteal artery) in 13 of 14 occlusions. The IPD algorithm achieved results within the range of the human readers in 11 of 14 cases. We conclude that the additional use of sparse but specific image space information, such as calcified atherosclerotic plaque, can be used to substantially improve the performance of a previously described knowledge-based method to restore the centerlines of femoropopliteal arterial occlusions. PMID:18697561

  18. Calibration and image quality performance results of RADARSAT

    NASA Astrophysics Data System (ADS)

    Srivastava, S. K.; Lukowski, T. I.; Gray, R. B.; Shepherd, N. W.; Banik, B.; Hawkins, R. K.; Cloutier, C.

    1997-05-01

    The Canadian earth observation satellite, RADARSAT, was launched in late 1995. The aim of this space borne Synthetic Aperture Radar (SAR) program is to provide C-band HH polarized SAR data products for five years at varying incidence angles, resolutions and area coverages. The system has been designed to produce imagery using single beams in elevation and also to operate in the ScanSAR mode by combining different elevation beams. SAR images have been obtained and were used to measure system performance during the Beam Qualification Phase. The measured image quality parameters for single beam products dealing with all aspects of image quality except radiometric calibration have been found to meet and exceed the system specifications. Based on the system performance and on completion of the commissioning activities, the Initial Operational Capability for the system was declared in April 1996.

  19. Automatic image quality assessment for uterine cervical imagery

    NASA Astrophysics Data System (ADS)

    Gu, Jia; Li, Wenjing

    2006-03-01

    Uterine cervical cancer is the second most common cancer among women worldwide. However, its death rate can be dramatically reduced by appropriate treatment, if early detection is available. We are developing a Computer-Aided-Diagnosis (CAD) system to facilitate colposcopic examinations for cervical cancer screening and diagnosis. Unfortunately, the effort to develop fully automated cervical cancer diagnostic algorithms is hindered by the paucity of high quality, standardized imaging data. The limited quality of cervical imagery can be attributed to several factors, including: incorrect instrumental settings or positioning, glint (specular reflection), blur due to poor focus, and physical contaminants. Glint eliminates the color information in affected pixels and can therefore introduce artifacts in feature extraction algorithms. Instrumental settings that result in an inadequate dynamic range or an overly constrained region of interest can reduce or eliminate pixel information and thus make image analysis algorithms unreliable. Poor focus causes image blur with a consequent loss of texture information. In addition, a variety of physical contaminants, such as blood, can obscure the desired scene and reduce or eliminate diagnostic information from affected areas. Thus, automated feedback should be provided to the colposcopist as a means to promote corrective actions. In this paper, we describe automated image quality assessment techniques, which include region of interest detection and assessment, contrast dynamic range assessment, blur detection, and contaminant detection. We have tested these algorithms using clinical colposcopic imagery, and plan to implement these algorithms in a CAD system designed to simplify high quality data acquisition. Moreover, these algorithms may also be suitable for image quality assessment in telemedicine applications.

  20. Image quality specification and maintenance for airborne SAR

    NASA Astrophysics Data System (ADS)

    Clinard, Mark S.

    2004-08-01

    Specification, verification, and maintenance of image quality over the lifecycle of an operational airborne SAR begin with the specification for the system itself. Verification of image quality-oriented specification compliance can be enhanced by including a specification requirement that a vendor provide appropriate imagery at the various phases of the system life cycle. The nature and content of the imagery appropriate for each stage of the process depends on the nature of the test, the economics of collection, and the availability of techniques to extract the desired information from the data. At the earliest lifecycle stages, Concept and Technology Development (CTD) and System Development and Demonstration (SDD), the test set could include simulated imagery to demonstrate the mathematical and engineering concepts being implemented thus allowing demonstration of compliance, in part, through simulation. For Initial Operational Test and Evaluation (IOT&E), imagery collected from precisely instrumented test ranges and targets of opportunity consisting of a priori or a posteriori ground-truthed cultural and natural features are of value to the analysis of product quality compliance. Regular monitoring of image quality is possible using operational imagery and automated metrics; more precise measurements can be performed with imagery of instrumented scenes, when available. A survey of image quality measurement techniques is presented along with a discussion of the challenges of managing an airborne SAR program with the scarce resources of time, money, and ground-truthed data. Recommendations are provided that should allow an improvement in the product quality specification and maintenance process with a minimal increase in resource demands on the customer, the vendor, the operational personnel, and the asset itself.

  1. 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.

  2. 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.

  3. Diagnostic and prognostic value of myocardial perfusion imaging in patients with known or suspected stable coronary artery disease.

    PubMed

    Amanullah, A M

    2000-08-01

    Coronary artery disease is the leading cause of complications and death in the United States and other Western countries, and stress myocardial perfusion study is an important component of the clinical evaluation, stratification, and management. This imaging technique is a well-established modality and has been widely used for the past three decades. New quantitative techniques for the assessment of ventricular function using quantitative gated single-photon emission computed tomography in addition to myocardial perfusion will potentially enhance the role of nuclear cardiology in the management of these patients. This review summarizes the current knowledge of the diagnostic and prognostic uses of stress myocardial perfusion imaging using exercise and pharmacological stress in patients with stable coronary artery disease. PMID:11000598

  4. Investigation of grid performance using simple image quality tests

    PubMed Central

    Bor, Dogan; Birgul, Ozlem; Onal, Umran; Olgar, Turan

    2016-01-01

    Antiscatter grids improve the X-ray image contrast at a cost of patient radiation doses. The choice of appropriate grid or its removal requires a good knowledge of grid characteristics, especially for pediatric digital imaging. The aim of this work is to understand the relation between grid performance parameters and some numerical image quality metrics for digital radiological examinations. The grid parameters such as bucky factor (BF), selectivity (Σ), Contrast improvement factor (CIF), and signal-to-noise improvement factor (SIF) were determined following the measurements of primary, scatter, and total radiations with a digital fluoroscopic system for the thicknesses of 5, 10, 15, 20, and 25 cm polymethyl methacrylate blocks at the tube voltages of 70, 90, and 120 kVp. Image contrast for low- and high-contrast objects and high-contrast spatial resolution were measured with simple phantoms using the same scatter thicknesses and tube voltages. BF and SIF values were also calculated from the images obtained with and without grids. The correlation coefficients between BF values obtained using two approaches (grid parameters and image quality metrics) were in good agreement. Proposed approach provides a quick and practical way of estimating grid performance for different digital fluoroscopic examinations.

  5. Potentials and Challenges for Arterial Spin Labeling in Pharmacological Magnetic Resonance Imaging

    PubMed Central

    Chen, Yufen; Fernández-Seara, María A.; Detre, John A.

    2011-01-01

    Pharmacological magnetic resonance imaging (phMRI) is increasingly being used in drug discovery and development to speed the translation from the laboratory to the clinic. The two primary methods in phMRI include blood-oxygen-level-dependent (BOLD) contrast and arterial spin-labeled (ASL) perfusion MRI. BOLD contrast has been widely applied in existing phMRI studies. However, because of the lack of absolute quantification and poor reproducibility over time scales longer than hours or across scanning sessions, BOLD fMRI may not be suitable to track oral and other long-term drug effects on baseline brain function. As an alternative method, ASL provides noninvasive, absolute quantification of cerebral blood flow both at rest and during task activation. ASL perfusion measurements have been shown to be highly reproducible over minutes and hours to days and weeks. These two characteristics make ASL an ideal tool for phMRI for studying both intravenous and oral drug action as well as understanding drug effects on baseline brain function and brain activation to cognitive or sensory processing. When ASL is combined with BOLD fMRI, drug-induced changes in cerebral metabolic rate of oxygen may also be inferred. Representative phMRI studies using ASL perfusion MRI on caffeine, remifentanil, and metoclopramide (dopamine antagonist) are reviewed here, with an emphasis on the methodologies used to control for potentially confounding vascular and systemic effects. Both the potentials and limitations of using ASL as an imaging marker of drug action are discussed. PMID:21317356

  6. Dynamic contrast-enhanced magnetic resonance imaging in patients with pulmonary arterial hypertension.

    PubMed

    Swift, Andrew J; Telfer, Adam; Rajaram, Smitha; Condliffe, Robin; Marshall, Helen; Capener, Dave; Hurdman, Judith; Elliot, Charlie; Kiely, David G; Wild, Jim M

    2014-03-01

    Dynamic contrast-enhanced (DCE) time-resolved magnetic resonance (MR) imaging is a technique whereby the passage of an intravenous contrast bolus can be tracked through the pulmonary vascular system. The aim of this study was to investigate the prognostic significance of DCE-MR pulmonary blood transit times in patients with pulmonary arterial hypertension (PAH). Seventy-nine patients diagnosed with PAH underwent pulmonary DCE imaging at 1.5 T using a time-resolved three-dimensional spoiled gradient echo sequence. The prognostic significance of two DCE parameters, full width at half maximum (FWHM) of the first-pass clearance curve and pulmonary transit time (PTT), along with demographic and invasive catheter measurements, was evaluated by univariate and bivariate Cox proportional hazards regression and Kaplan-Meier analysis. DCE-MR transit times were most closely correlated with cardiac index (CI) and pulmonary vascular resistance index (PVRI) and were both found to be accurate for detecting reduced CI (FWHM area under the curve [AUC] at receiver operating characteristic analysis = 0.91 and PTT AUC = 0.92, respectively) and for detecting elevated PVRI (FWHM AUC = 0.88 and PTT AUC = 0.84, respectively). During the follow-up period, 25 patients died. Patients with longer measurements of FWHM (P = 0.0014) and PTT (P = 0.004) were associated with poor outcome at Kaplan-Meier analysis, and both parameters were strong predictors of adverse outcome from Cox proportional hazards analysis (P = 0.013 and 0.010, respectively). At bivariate analysis, DCE measurements predicted mortality independent of age, gender, and World Health Organization functional class; however, invasive hemodynamic indexes CI, PVRI, and DCE measurements were not independent of one another. In conclusion, DCE-MR transit times predict mortality in patients with PAH and are closely associated with clinical gold standards CI and PVRI. PMID:25006422

  7. Potentials and challenges for arterial spin labeling in pharmacological magnetic resonance imaging.

    PubMed

    Wang, Danny J J; Chen, Yufen; Fernández-Seara, María A; Detre, John A

    2011-05-01

    Pharmacological magnetic resonance imaging (phMRI) is increasingly being used in drug discovery and development to speed the translation from the laboratory to the clinic. The two primary methods in phMRI include blood-oxygen-level-dependent (BOLD) contrast and arterial spin-labeled (ASL) perfusion MRI. BOLD contrast has been widely applied in existing phMRI studies. However, because of the lack of absolute quantification and poor reproducibility over time scales longer than hours or across scanning sessions, BOLD fMRI may not be suitable to track oral and other long-term drug effects on baseline brain function. As an alternative method, ASL provides noninvasive, absolute quantification of cerebral blood flow both at rest and during task activation. ASL perfusion measurements have been shown to be highly reproducible over minutes and hours to days and weeks. These two characteristics make ASL an ideal tool for phMRI for studying both intravenous and oral drug action as well as understanding drug effects on baseline brain function and brain activation to cognitive or sensory processing. When ASL is combined with BOLD fMRI, drug-induced changes in cerebral metabolic rate of oxygen may also be inferred. Representative phMRI studies using ASL perfusion MRI on caffeine, remifentanil, and metoclopramide (dopamine antagonist) are reviewed here, with an emphasis on the methodologies used to control for potentially confounding vascular and systemic effects. Both the potentials and limitations of using ASL as an imaging marker of drug action are discussed. PMID:21317356

  8. 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.

  9. CT image quality over time: comparison of image quality for six different CT scanners over a six-year period.

    PubMed

    Roa, Ana Maria A; Andersen, Hilde K; Martinsen, Anne Catrine T

    2015-01-01

    UNSCEAR concluded that increased use of CT scanning caused dramatic changes in population dose. Therefore, international radiation protection authorities demand: 1) periodical quality assurance tests with respect to image quality and radiation dose, and 2) optimization of all examination protocols with respect to image quality and radiation dose. This study aimed to evaluate and analyze multiple image quality parameters and variability measured throughout time for six different CT scanners from four different vendors, in order to evaluate the current methodology for QA controls of CT systems. The results from this study indicate that there is minor drifting in the image noise and uniformity and in the spatial resolution over time for CT scanners, independent of vendors. The HU for different object densities vary between different CT scanner models from different vendors, and over time for one specific CT scanner. Future tests of interphantom and intraphantom variations, along with inclusion of more CT scanners, are necessary to establish robust baselines and recommendations of methodology for QA controls of CT systems, independent of model and vendor. PMID:26103172

  10. Labeling the pulmonary arterial tree in CT images for automatic quantification of pulmonary embolism

    NASA Astrophysics Data System (ADS)

    Peters, Ralph J. M.; Marquering, Henk A.; Doğan, Halil; Hendriks, Emile A.; de Roos, Albert; Reiber, Johan H. C.; Stoel, Berend C.

    2007-03-01

    Contrast-enhanced CT Angiography has become an accepted diagnostic tool for detecting Pulmonary Embolism (PE). The CT obstruction index proposed by Qanadli, which is based on the number of obstructed arterial segments, enables the quantification of PE severity. Because the required manual identification of twenty arterial segments is time consuming, we propose a method for automated labeling of the pulmonary arterial tree to identify the arterial segments. Assuming that the peripheral parts of the arterial tree contain most relevant information for labeling, we propose a bottom-up labeling algorithm exploiting the spatial information of the peripheral arteries. A model of reference positions of the arterial segments was trained using manually labeled trees of 9 patients. To improve accuracy, the arterial tree was partitioned into sub-trees enabling an iterative labeling technique that labels each sub-tree separately. The accuracy of the labeling technique was evaluated using manually labeled trees of 10 patients. Initially an accuracy of 74% was obtained, whereas the iterative approach improved accuracy to 85%. The labeling errors had minor effects on the calculated Qanadli index. Therefore, the presented labeling approach is applicable in automated PE quantification.

  11. Integration of multi-modality imaging for accurate 3D reconstruction of human coronary arteries in vivo

    NASA Astrophysics Data System (ADS)

    Giannoglou, George D.; Chatzizisis, Yiannis S.; Sianos, George; Tsikaderis, Dimitrios; Matakos, Antonis; Koutkias, Vassilios; Diamantopoulos, Panagiotis; Maglaveras, Nicos; Parcharidis, George E.; Louridas, George E.

    2006-12-01

    In conventional intravascular ultrasound (IVUS)-based three-dimensional (3D) reconstruction of human coronary arteries, IVUS images are arranged linearly generating a straight vessel volume. However, with this approach real vessel curvature is neglected. To overcome this limitation an imaging method was developed based on integration of IVUS and biplane coronary angiography (BCA). In 17 coronary arteries from nine patients, IVUS and BCA were performed. From each angiographic projection, a single end-diastolic frame was selected and in each frame the IVUS catheter was interactively detected for the extraction of 3D catheter path. Ultrasound data was obtained with a sheath-based catheter and recorded on S-VHS videotape. S-VHS data was digitized and lumen and media-adventitia contours were semi-automatically detected in end-diastolic IVUS images. Each pair of contours was aligned perpendicularly to the catheter path and rotated in space by implementing an algorithm based on Frenet-Serret rules. Lumen and media-adventitia contours were interpolated through generation of intermediate contours creating a real 3D lumen and vessel volume, respectively. The absolute orientation of the reconstructed lumen was determined by back-projecting it onto both angiographic planes and comparing the projected lumen with the actual angiographic lumen. In conclusion, our method is capable of performing rapid and accurate 3D reconstruction of human coronary arteries in vivo. This technique can be utilized for reliable plaque morphometric, geometrical and hemodynamic analyses.

  12. Magnetic Resonance Imaging of Coronary Arteries and Heart Valves in a Living Mouse: Techniques and Preliminary Results

    NASA Astrophysics Data System (ADS)

    Ruff, Jan; Wiesmann, Frank; Lanz, Titus; Haase, Axel

    2000-10-01

    New investigations in MRI of a mouse heart showed high-contrast cardiac images and thereby the possibility of doing functional cardiac studies of in vivo mice. But is MRI, in addition, capable of visualizing microstructures such as the coronary arteries and the heart valves of a living mouse? To answer this question, 2D and 3D gradient echo sequences with and without flow compensation were used to image the coronary arteries. To increase signal-to-noise ratio, a birdcage resonator was optimized for mouse heart imaging. Contrast between blood and myocardium was achieved through the inflow effect. A segmented three-dimensional FLASH sequence acquired with a multiple overlap thin slab technique showed the best results. With this technique an isotropic resolution of 100 ?m was achieved. The left coronary artery could be visualized up to the apex of the heart. This is demonstrated with short axis views and 3D surface reconstructions of the mouse heart. The four cardiac valves were also visible with the 3D method.

  13. Cardiac CT: coronary arteries and beyond.

    PubMed

    Mahnken, Andreas H; Mühlenbruch, Georg; Günther, Rolf W; Wildberger, Joachim E

    2007-04-01

    Multi-detector-row computed tomography (MDCT) has emerged as a rapidly developing method for non-invasive imaging of the heart. An understanding of ECG synchronization, contrast material administration, patient preparation and image post-processing is needed to optimize image quality. The basic technical principles and essentials of these technical basics are described here. Correctly applied cardiac MDCT allows imaging of the coronary arteries including coronary anatomy and stenosis detection. The same is true for evaluation of coronary artery bypass grafts and, to some extent, coronary artery stents. While quantification of total calcified plaque burden has been long established, coronary MDCT allows assessing plaque morphology and constitution. Recent approaches go beyond the coronaries and include evaluation of left ventricular function at rest and myocardial viability. In combination with experimental approaches for assessing aortic valve function and myocardial perfusion imaging, cardiac MDCT offers the potential for a comprehensive examination of the heart using a single breath-hold examination. PMID:17066290

  14. Effect of exercise supplementation on dipyridamole thallium-201 image quality

    SciTech Connect

    Stern, S.; Greenberg, I.D.; Corne, R. )

    1991-08-01

    To determine the effect of different types of exercise supplementation on dipyridamole thallium image quality, 78 patients were prospectively randomized to one of three protocols: dipyridamole infusion alone, dipyridamole supplemented with isometric handgrip, and dipyridamole with low-level treadmill exercise. Heart-to-lung, heart-to-liver, and heart-to-adjacent infradiaphragmatic activity ratios were generated from anterior images acquired immediately following the test. Additionally, heart-to-total infradiaphragmatic activity was graded semiquantitatively. Results showed a significantly higher ratio of heart to subdiaphragmatic activity in the treadmill group as compared with dipyridamole alone (p less than 0.001) and dipyridamole supplemented with isometric handgrip exercise (p less than 0.001). No significant difference was observed between patients receiving the dipyridamole infusion, and dipyridamole supplemented with isometric handgrip exercise. The authors conclude that low-level treadmill exercise supplementation of dipyridamole infusion is an effective means of improving image quality. Supplementation with isometric handgrip does not improve image quality over dipyridamole alone.

  15. Evaluation of image quality characteristics of reduction image in high resolution liquid crystal display

    NASA Astrophysics Data System (ADS)

    Kimura, Yukiyoshi; Yokoyama, Daigo; Fujita, Naotoshi; Kodera, Yoshie

    2011-03-01

    With recent developments, digital mammograms can be obtained with a small pixel size, i.e., high resolution; however, the matrix size increases. Therefore, when the image is thinned out, image information is lost when the image is displayed on a liquid crystal display (LCD). To resolve this issue, we have developed a super high resolution liquid crystal display (SHR-LCD) by using a novel resolution enhancement technology for independent subpixel driving (ISD) with three subpixels in each pixel element. However, the lack of image information caused by thinning of the image cannot be ignored because the matrix size of a phase contrast mammogram (PCM) is very large as compared to that of a conventional mammogram. We obtained noise and edge images by using the geometrical layouts of the PCM (7080 x 9480). We measured the Wiener spectrum (WS), modulation transfer function (MTF), and noise-equivalent number of quanta (NEQ) of the images reduced by the nearest-neighbor, bilinear, and bicubic (sharpness and smooth) interpolations. The reduction rate was approximately 0.14. We measured the WS and MTF when the PCM image was displayed on a 5-megapixel (MP) and 15-MP LCD. The bilinear interpolation technique gave the best image quality. The image quality was further improved by using a 15-MP SHR-LCD.

  16. 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.

  17. 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.

  18. 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.

  19. Optimizing 3D image quality and performance for stereoscopic gaming

    NASA Astrophysics Data System (ADS)

    Flack, Julien; Sanderson, Hugh; Pegg, Steven; Kwok, Simon; Paterson, Daniel

    2009-02-01

    The successful introduction of stereoscopic TV systems, such as Samsung's 3D Ready Plasma, requires high quality 3D content to be commercially available to the consumer. Console and PC games provide the most readily accessible source of high quality 3D content. This paper describes innovative developments in a generic, PC-based game driver architecture that addresses the two key issues affecting 3D gaming: quality and speed. At the heart of the quality issue are the same considerations that studios face producing stereoscopic renders from CG movies: how best to perform the mapping from a geometric CG environment into the stereoscopic display volume. The major difference being that for game drivers this mapping cannot be choreographed by hand but must be automatically calculated in real-time without significant impact on performance. Performance is a critical issue when dealing with gaming. Stereoscopic gaming has traditionally meant rendering the scene twice with the associated performance overhead. An alternative approach is to render the scene from one virtual camera position and use information from the z-buffer to generate a stereo pair using Depth-Image-Based Rendering (DIBR). We analyze this trade-off in more detail and provide some results relating to both 3D image quality and render performance.

  20. Using advanced noninvasive imaging techniques to probe the links between regional coronary artery endothelial dysfunction and atherosclerosis

    PubMed Central

    Iantorno, Micaela; Weiss, Robert G.

    2015-01-01

    Cardiovascular disease remains the number one cause of death in the US annually. The development in recent years of imaging strategies that can identify coronary endothelial dysfunction noninvasively provide new information about the early presence and local spatial heterogeneity of endothelial function in patients with, and those at risk for, coronary artery disease. In this summary, we will briefly review the mechanisms relating endothelial function and atherosclerosis, contemporary imaging strategies now able to quantify coronary endothelial function noninvasively, and recent insights on human coronary endothelial function. PMID:24296299

  1. Study on classification of pork quality using hyperspectral imaging technique

    NASA Astrophysics Data System (ADS)

    Zeng, Shan; Bai, Jun; Wang, Haibin

    2015-12-01

    The relative problems' research of chilled meat, thawed meat and spoiled meat discrimination by hyperspectral image technique were proposed, such the section of feature wavelengths, et al. First, based on 400 ~ 1000nm range hyperspectral image data of testing pork samples, by K-medoids clustering algorithm based on manifold distance, we select 30 important wavelengths from 753 wavelengths, and thus select 8 feature wavelengths (454.4, 477.5, 529.3, 546.8, 568.4, 580.3, 589.9 and 781.2nm) based on the discrimination value. Then 8 texture features of each image under 8 feature wavelengths were respectively extracted by two-dimensional Gabor wavelets transform as pork quality feature. Finally, we build a pork quality classification model using the fuzzy C-mean clustering algorithm. Through the experiment of extracting feature wavelengths, we found that although the hyperspectral images between adjacent bands have a strong linear correlation, they show a significant non-linear manifold relationship from the entire band. K-medoids clustering algorithm based on manifold distance used in this paper for selecting the characteristic wavelengths, which is more reasonable than traditional principal component analysis (PCA). Through the classification result, we conclude that hyperspectral imaging technology can distinguish among chilled meat, thawed meat and spoiled meat accurately.

  2. Spread spectrum image watermarking based on perceptual quality metric.

    PubMed

    Zhang, Fan; Liu, Wenyu; Lin, Weisi; Ngan, King Ngi

    2011-11-01

    Efficient image watermarking calls for full exploitation of the perceptual distortion constraint. Second-order statistics of visual stimuli are regarded as critical features for perception. This paper proposes a second-order statistics (SOS)-based image quality metric, which considers the texture masking effect and the contrast sensitivity in Karhunen-Loève transform domain. Compared with the state-of-the-art metrics, the quality prediction by SOS better correlates with several subjectively rated image databases, in which the images are impaired by the typical coding and watermarking artifacts. With the explicit metric definition, spread spectrum watermarking is posed as an optimization problem: we search for a watermark to minimize the distortion of the watermarked image and to maximize the correlation between the watermark pattern and the spread spectrum carrier. The simple metric guarantees the optimal watermark a closed-form solution and a fast implementation. The experiments show that the proposed watermarking scheme can take full advantage of the distortion constraint and improve the robustness in return. PMID:21518660

  3. Novel MOS prediction models for compressed medical image quality.

    PubMed

    Kumar, B; Singh, S P; Mohan, A; Anand, A

    2011-01-01

    This paper presents the development of novel models which can be potentially useful in determining the upper limit of image compression thresholds, to preserve diagnostically relevant information in compressed medical images. These models were developed by evolving the correlation between the theoretically computed objective (peak signal-to-noise ratio and structural similarity) and subjective mean opinion score (MOS) quality parameters. The developed models were validated by comparing the model generated MOS with the corresponding experimental MOS of six independent observers considering joint photographic experts group (JPEG), JPEG2000 and set partitioning in hierarchical trees (SPIHT) compressions of computed tomography (CT) scan images. It is found that the correlation between the model generated and experimental MOS and PRD are ≥0.87 and ≤13% respectively for the compression range 0.05-2.0 bits/pixel of the CT scan images. Therefore our models can be potentially useful for observer-independent MOS prediction and quality assessment of reconstructed medical images. In addition this also avoids the need for exhaustive and time-consuming experimental MOS and thus it can be more suitable for teleradiology applications. PMID:21401314

  4. Quality assessment of butter cookies applying multispectral imaging

    PubMed Central

    Andresen, Mette S; Dissing, Bjørn S; Løje, Hanne

    2013-01-01

    A method for characterization of butter cookie quality by assessing the surface browning and water content using multispectral images is presented. Based on evaluations of the browning of butter cookies, cookies were manually divided into groups. From this categorization, reference values were calculated for a statistical prediction model correlating multispectral images with a browning score. The browning score is calculated as a function of oven temperature and baking time. It is presented as a quadratic response surface. The investigated process window was the intervals 4–16 min and 160–200°C in a forced convection electrically heated oven. In addition to the browning score, a model for predicting the average water content based on the same images is presented. This shows how multispectral images of butter cookies may be used for the assessment of different quality parameters. Statistical analysis showed that the most significant wavelengths for browning predictions were in the interval 400–700 nm and the wavelengths significant for water prediction were primarily located in the near-infrared spectrum. The water prediction model was found to correctly estimate the average water content with an absolute error of 0.22%. From the images it was also possible to follow the browning and drying propagation from the cookie edge toward the center. PMID:24804036

  5. 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.

  6. A quality assurance phantom for electronic portal imaging devices.

    PubMed

    Das, Indra J; Cao, Minsong; Cheng, Chee-Wai; Misic, Vladimir; Scheuring, Klaus; Schüle, Edmund; Johnstone, Peter A S

    2011-01-01

    Electronic portal imaging device (EPID) plays an important role in radiation therapy portal imaging, geometric and dosimetric verification. Consistent image quality and stable radiation response is necessary for proper utilization that requires routine quality assurance (QA). A commercial 'EPID QC' phantom weighing 3.8 kg with a dimension of 25 × 25 × 4.8 cm³ is used for EPID QA. This device has five essential tools to measure the geometric accuracy, signal-to-noise ratio (SNR), dose linearity, and the low- and the high-contrast resolutions. It is aligned with beam divergence to measure the imaging and geometric parameters in both X and Y directions, and can be used as a baseline check for routine QA. The low-contrast tool consists of a series of holes with various diameters and depths in an aluminum slab, very similar to the Las Vegas phantom. The high-resolution contrast tool provides the modulation transfer function (MTF) in both the x- and y-dimensions to measure the focal spot of linear accelerator that is important for imaging and small field dosimetry. The device is tested in different institutions with various amorphous silicon imagers including Elekta, Siemens and Varian units. Images of the QA phantom were acquired at 95.2 cm source-skin-distance (SSD) in the range 1-15MU for a 26 × 26 cm² field and phantom surface is set normal to the beam direction when gantry is at 0° and 90°. The epidSoft is a software program provided with the EPID QA phantom for analysis of the data. The preliminary results using the phantom on the tested EPID showed very good low-contrast resolution and high resolution, and an MTF (0.5) in the range of 0.3-0.4 lp/mm. All imagers also exhibit satisfactory geometric accuracy, dose linearity and SNR, and are independent of MU and spatial orientations. The epidSoft maintains an image analysis record and provides a graph of the temporal variations in imaging parameters. In conclusion, this device is simple to use and provides testing on basic and advanced imaging parameters for daily QA on any imager used in clinical practices. PMID:21587179

  7. 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.

  8. 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

  9. 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.

  10. 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

  11. Value of tomographic thallium-201 imaging in patients with chest pain following coronary artery bypass grafting

    SciTech Connect

    Starling, M.R.; Walsh, R.A.; Dehmer, G.J.; Lasher, J.C.; Blumhardt, R.

    1987-02-01

    To determine whether thallium-201 washout profile analysis can detect regional myocardial ischemia caused by coronary artery bypass graft occlusion or progression of disease in nonbypassed coronary arteries, 19 consecutive patients with chest pain following bypass grafting were evaluated with coronary arteriography and thallium-201 scintigraphy. Twenty of the 55 coronary artery regions were perfused by an occluded bypass graft or a significantly stenosed (greater than or equal to 70% diameter narrowing) nonbypassed coronary artery, while 35 coronary regions were perfused by patent bypass grafts or insignificantly diseased coronary arteries. The tomographic thallium-201 washout profile results correlated with the bypass graft and coronary arteriographic findings. The sensitivity of tomographic thallium-201 washout profile abnormalities for arteriographic abnormalities was 75%, while the specificity was 86%. The authors conclude that tomographic thallium-201 washout profile analysis may be very useful in the evaluation of patients with chest pain following coronary artery bypass grafting by detecting regional myocardial ischemia caused by occlusion of specific bypass grafts or progression of disease in nonbypassed coronary arteries.

  12. In-situ characterization of the uncrimping process of arterial collagen fibers using two-photon confocal microscopy and digital image correlation.

    PubMed

    Wang, Ruoya; Brewster, Luke P; Gleason, Rudolph L

    2013-10-18

    Uncrimping of collagen fibers in the arterial wall is an integral process in regulating the macro-level mechanical response of arteries. Uncrimping of collagen fibers leads to a gradual, but significant strain-stiffening response of the artery at physiological pressures and prevents overdistention at elevated pressures. In this study, we imaged adventitial collagen fibers from fresh primate arteries using two-photon excitation microscopy while subjecting the arteries to physiological inflation pressures and axial stretches. The imaging focal plane was fixed at a constant radial location in the adventitial wall by adjusting the focal distance as the arteries inflated, allowing for the continuously monitoring of the uncrimping process of a single region of collagen fibers. Digital image correlation was then applied to the sequential images to assess and correlate the local displacements to manual traces of selected reference fibers and their engagements. We found that the collagen fibers of interest became fully engaged at a luminal pressure of 20mmHg, this was then followed by rotation of these fibers as the bulk artery continued to dilate. This technique helps to further the understanding of the uncrimping process of collagen fibers under physiological loads, which can aid in the development of more accurate microstructural constitutive models. PMID:24050510

  13. Development and evaluation of a semiautomatic 3D segmentation technique of the carotid arteries from 3D ultrasound images

    NASA Astrophysics Data System (ADS)

    Gill, Jeremy D.; Ladak, Hanif M.; Steinman, David A.; Fenster, Aaron

    1999-05-01

    In this paper, we report on a semi-automatic approach to segmentation of carotid arteries from 3D ultrasound (US) images. Our method uses a deformable model which first is rapidly inflated to approximately find the boundary of the artery, then is further deformed using image-based forces to better localize the boundary. An operator is required to initialize the model by selecting a position in the 3D US image, which is within the carotid vessel. Since the choice of position is user-defined, and therefore arbitrary, there is an inherent variability in the position and shape of the final segmented boundary. We have assessed the performance of our segmentation method by examining the local variability in boundary shape as the initial selected position is varied in a freehand 3D US image of a human carotid bifurcation. Our results indicate that high variability in boundary position occurs in regions where either the segmented boundary is highly curved, or the 3D US image has poorly defined vessel edges.

  14. The use of storage phosphors for portal imaging in radiation therapy: therapists' perception of image quality.

    PubMed

    Gur, D; Deutsch, M; Fuhrman, C R; Clayton, P A; Weiser, J C; Rosenthal, M S; Bukovitz, A G

    1989-01-01

    Two drawbacks in quality of portal radiographs in radiation therapy are their low contrast and low spatial resolution. These are due to the low differential absorption of body tissues at therapeutic energies and to a relatively large radiation source. We used an experimental, high-contrast sensitivity storage phosphor imaging system (Eastman Kodak Co.) to produce portal images. The system consists of a storage phosphor detector, a high-contrast sensitivity laser scanner (12 bit), an image processing module, and a laser printer (12 bit). Patients undergoing radiation therapy treatments had both a conventional portal image and a storage phosphor image taken. Both were displayed side-by-side and were evaluated independently by three radiotherapists according to quality of information to verify the treatment field. Each of the three radiotherapists rated the storage phosphor images to be better (p less than 0.001) than the conventional images. However, rated improvements of low-contrast storage phosphor images of the pelvis and abdomen (40) were significantly lower than those of high-contrast (head, neck, and chest) images (53). PMID:2921972

  15. Characterization of image quality and image-guidance performance of a preclinical microirradiator

    SciTech Connect

    Clarkson, R.; Lindsay, P. E.; Ansell, S.; Wilson, G.; Jelveh, S.; Hill, R. P.; Jaffray, D. A.

    2011-02-15

    Purpose: To assess image quality and image-guidance capabilities of a cone-beam CT based small-animal image-guided irradiation unit (micro-IGRT). Methods: A micro-IGRT system has been developed in collaboration with the authors' laboratory as a means to study the radiobiological effects of conformal radiation dose distributions in small animals. The system, the X-Rad 225Cx, consists of a 225 kVp x-ray tube and a flat-panel amorphous silicon detector mounted on a rotational C-arm gantry and is capable of both fluoroscopic x-ray and cone-beam CT imaging, as well as image-guided placement of the radiation beams. Image quality (voxel noise, modulation transfer, CT number accuracy, and geometric accuracy characteristics) was assessed using water cylinder and micro-CT test phantoms. Image guidance was tested by analyzing the dose delivered to radiochromic films fixed to BB's through the end-to-end process of imaging, targeting the center of the BB, and irradiation of the film/BB in order to compare the offset between the center of the field and the center of the BB. Image quality and geometric studies were repeated over a 5-7 month period to assess stability. Results: CT numbers reported were found to be linear (R{sup 2}{>=}0.998) and the noise for images of homogeneous water phantom was 30 HU at imaging doses of approximately 1 cGy (to water). The presampled MTF at 50% and 10% reached 0.64 and 1.35 mm{sup -1}, respectively. Targeting accuracy by means of film irradiations was shown to have a mean displacement error of [{Delta}x,{Delta}y,{Delta}z]=[-0.12,-0.05,-0.02] mm, with standard deviations of [0.02, 0.20, 0.17] mm. The system has proven to be stable over time, with both the image quality and image-guidance performance being reproducible for the duration of the studies. Conclusions: The micro-IGRT unit provides soft-tissue imaging of small-animal anatomy at acceptable imaging doses ({<=}1 cGy). The geometric accuracy and targeting systems permit dose placement with submillimeter accuracy and precision. The system has proven itself to be stable over 2 yr of routine laboratory use (>1800 irradiations) and provides a platform for the exploration of targeted radiation effects in small-animal models.

  16. Image Quality and Performance of the LSST Camera

    NASA Astrophysics Data System (ADS)

    Gilmore, D. Kirk; Kahn, S.; Rassmussen, A.; Singel, J.

    2012-01-01

    The LSST camera, which will be the largest digital camera built to date, presents a number of novel challenges. The field of view will be 3.5 degrees in diameter and will be sampled by a 3.2 billion pixel array of sensors to be read-out in under 2 seconds, which leads to demanding constraints on the sensor architecture and read-out electronics. The camera also incorporates three large refractive lenses, an array of five wide-band large filters mounted on a carousel, and a mechanical shutter. Given the fast optical beam (f/1.2) and tight tolerances for image quality and throughput specifications, the requirements on the optical design, assembly and alignment, and contamination control of the optical elements and focal plane are crucial. We present an overview of the LSST camera, with an emphasis on models of camera image quality and throughput performance that are characterized by various analysis packages and design considerations.

  17. [The Quality Assurance (QA) and the Quality Control (QC) of Positron Emission Tomography (PET) Image].

    PubMed

    Iimori, Takashi

    2015-01-01

    Positron emission tomography (PET) is widely used for image diagnostics; making judgments for early diagnostics, differential diagnostics, staging and treatment effect. As for undertaking the large clinical trial and the multicenter study using several diagnostics, the quantitative standardization of PET images is important. We should maintain the safety and the accuracy of daily clinical images. Moreover, we have to develop a safety treatment manual for instruments, apparatus and radiopharmaceuticals in order to produce PET studies of the highest diagnostic accuracy. In addition, daily quality assurance (QA) and quality control (QC) are very important in order to achieve efficiency and safety of PET studies. The importance of the QA and the QC have been recognized from the view of clinical incident protection points. PET will become more advanced in the future, and therefore the QA and the QC for PET images will continue to important in our work. In the view-risk management, we should reaffirm the importance of both QA and QC. Furthermore, we underline the importance of the constant management system and organization in order to gain the quality enhancement of PET imaging. PMID:26753393

  18. Measuring image quality performance on image versions saved with different file format and compression ratio

    NASA Astrophysics Data System (ADS)

    Mitjà, Carles; Escofet, Jaume; Bover, Toni

    2012-06-01

    Digitization of existing documents containing images is an important body of work for many archives ranging from individuals to institutional organizations. The methods and file formats used in this digitization is usually a trade off between budget, file volume size and image quality, while not necessarily in this order. The use of most commons and standardized file formats, JPEG and TIFF, prompts the operator to decide the compression ratio that affects both the final file volume size and the quality of the resulting image version. The evaluation of the image quality achieved by a system can be done by means of several measures and methods, being the Modulation Transfer Function (MTF) one of most used. The methods employed by the compression algorithms affect in a different way the two basic features of the image contents, edges and textures. Those basic features are too differently affected by the amount of noise generated at the digitization stage. Therefore, the target used in the measurement should be related with the features usually presents in general imaging. This work presents a comparison between the results obtained by measuring the MTF of images taken with a professional camera system and saved in several file formats compression ratios. In order to accomplish with the needs early stated, the MTF measurement has been done by two separate methods using the slanted edge and dead leaves targets respectively. The measurement results are shown and compared related with the respective file volume size.

  19. Three-dimensional reconstruction of the coronary arterial tree from several sets of biplane angiograms with simultaneous estimation of imaging geometry

    NASA Astrophysics Data System (ADS)

    Sugimoto, Naozo; Uyama, Chikao; Mizuta, Shinobu; Watabe, Hiroshi; Urayama, Shin-ichi

    1997-04-01

    A new method is proposed for reconstructing the 3D structure of the coronary arterial tree from angiograms. Instead of identification of corresponding points on the images, several sets of biplane angiograms are used, and the parameters of the imaging geometries are simultaneously estimated. Several sets of biplane angiograms are usually obtained during one angiographic test. However, only one set of biplane angiogram is usually used for 3D reconstruction of the coronary arterial tree. If only one set of biplane angiogram is used for 3D reconstruction, it is necessary to identify corresponding points on both images. Identification of correspondent points on both images is, however, very difficult and often impossible. To overcome this difficulty, we use several sets of biplane angiograms for 3D reconstruction. If the precise parameters of the imaging geometries are known, the 3D structure of the coronary arterial tree can be obtained by back parameters of the imaging geometries are known, the 3D structure of the coronary arterial tree can be obtained by back projecting each angiogram. However, only the approximate parameters of the imaging geometries are usually known. Therefore, we developed a method for 3D reconstruction of a coronary arterial tree with simultaneous estimation of the imaging geometry. In this paper, we present the algorithm for our method and demonstrate the application to clinical data.

  20. Incorporating detection tasks into the assessment of CT image quality

    NASA Astrophysics Data System (ADS)

    Scalzetti, E. M.; Huda, W.; Ogden, K. M.; Khan, M.; Roskopf, M. L.; Ogden, D.

    2006-03-01

    The purpose of this study was to compare traditional and task dependent assessments of CT image quality. Chest CT examinations were obtained with a standard protocol for subjects participating in a lung cancer-screening project. Images were selected for patients whose weight ranged from 45 kg to 159 kg. Six ABR certified radiologists subjectively ranked these images using a traditional six-point ranking scheme that ranged from 1 (inadequate) to 6 (excellent). Three subtle diagnostic tasks were identified: (1) a lung section containing a sub-centimeter nodule of ground-glass opacity in an upper lung (2) a mediastinal section with a lymph node of soft tissue density in the mediastinum; (3) a liver section with a rounded low attenuation lesion in the liver periphery. Each observer was asked to estimate the probability of detecting each type of lesion in the appropriate CT section using a six-point scale ranging from 1 (< 10%) to 6 (> 90%). Traditional and task dependent measures of image quality were plotted as a function of patient weight. For the lung section, task dependent evaluations were very similar to those obtained using the traditional scoring scheme, but with larger inter-observer differences. Task dependent evaluations for the mediastinal section showed no obvious trend with subject weight, whereas there the traditional score decreased from ~4.9 for smaller subjects to ~3.3 for the larger subjects. Task dependent evaluations for the liver section showed a decreasing trend from ~4.1 for the smaller subjects to ~1.9 for the larger subjects, whereas the traditional evaluation had a markedly narrower range of scores. A task-dependent method of assessing CT image quality can be implemented with relative ease, and is likely to be more meaningful in the clinical setting.

  1. Digital chest radiography image quality assessment with dose reduction.

    PubMed

    Grewal, R K; Young, N; Colins, L; Karunnaratne, N; Sabharwal, N

    2012-03-01

    A retrospective study of digital chest radiography was performed to compare the image quality and dose parameters from two X-ray rooms in different areas of the same hospital using identical X-ray units but different local protocol for obtaining chest PA and lateral radiographs. Image quality of radiographs was assessed from the printed films using well established European guidelines and modified criteria. Patient entrance surface air kerma was calculated using technical data recorded for each radiograph and measured output of the X-ray unit. Effective dose and dose to radiosensitive organs was estimated using dose calculation software PCXMC. There was no statistical significant difference in the evaluated image quality using either technique, median entrance surface air kerma to the patient reduced significantly with added filtration technique and use of normal density setting. Phantom measurements indicated that an additional filtration of 0.1 mm Cu + 1 mm Al in the X-ray beam alone reduced the entrance surface air kerma by 35%. PMID:22302464

  2. 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

  3. Radiometric Quality Evaluation of INSAT-3D Imager Data

    NASA Astrophysics Data System (ADS)

    Prakash, S.; Jindal, D.; Badal, N.; Kartikeyan, B.; Gopala Krishna, B.

    2014-11-01

    INSAT-3D is an advanced meteorological satellite of ISRO which acquires imagery in optical and infra-red (IR) channels for study of weather dynamics in Indian sub-continent region. In this paper, methodology of radiometric quality evaluation for Level-1 products of Imager, one of the payloads onboard INSAT-3D, is described. Firstly, overall visual quality of scene in terms of dynamic range, edge sharpness or modulation transfer function (MTF), presence of striping and other image artefacts is computed. Uniform targets in Desert and Sea region are identified for which detailed radiometric performance evaluation for IR channels is carried out. Mean brightness temperature (BT) of targets is computed and validated with independently generated radiometric references. Further, diurnal/seasonal trends in target BT values and radiometric uncertainty or sensor noise are studied. Results of radiometric quality evaluation over duration of eight months (January to August 2014) and comparison of radiometric consistency pre/post yaw flip of satellite are presented. Radiometric Analysis indicates that INSAT-3D images have high contrast (MTF > 0.2) and low striping effects. A bias of <4K is observed in the brightness temperature values of TIR-1 channel measured during January-August 2014 indicating consistent radiometric calibration. Diurnal and seasonal analysis shows that Noise equivalent differential temperature (NEdT) for IR channels is consistent and well within specifications.

  4. Pleiades-Hr Innovative Techniques for Geometric Image Quality Commissioning

    NASA Astrophysics Data System (ADS)

    Greslou, D.; de Lussy, F.; Delvit, J. M.; Dechoz, C.; Amberg, V.

    2012-07-01

    Since the beginning of 2012, the first Pleiades-HR satellite of the program conducted by the French National Space Agency, CNES, delivers 20 km wide color scenes with a 70 cm ground sampling distance. A second satellite should be launched in 2013 which will achieve an almost world-wide coverage with a revisit interval of 24h. The assessment of the image quality and the calibration operation have been performed by CNES Image Quality team during the 6 month commissioning phase that followed the satellite launch. The geometric commissioning activities consist in improve the geometric quality of the images in order to meet very demanding specifications as localization accuracy, local coherence, dynamic stability, length alteration … This goal has been achieved through the implementation of new methods of calibration and performance assessment. Some of these methods are based on the exploitation of very specific satellite acquisitions that have been achieved thanks to the amazing agility of the Pleiades satellite. Thus, many stars acquisitions and very slow earth pictures have been processed to characterize dynamic phenomena. Similarly, "along-cross track" pairs have been exploited to improve the accuracy of the focal plane description. This paper deals with these new methods. It describes their accuracy and their operational interests.

  5. 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.

  6. Pleiades-Hr Innovative Techniques for Radiometric Image Quality Commissioning

    NASA Astrophysics Data System (ADS)

    Blanchet, G.; Lebeque, L.; Fourest, S.; Latry, C.; Porez-Nadal, F.; Lacherade, S.; Thiebaut, C.

    2012-07-01

    The first Pleiades-HR satellite, part of a constellation of two, has been launched on December 17, 2011. This satellite produces high resolution optical images. In order to achieve good image quality, Pleiades-HR should first undergo an important 6 month commissioning phase period. This phase consists in calibrating and assessing the radiometric and geometric image quality to offer the best images to end users. This new satellite has benefited from technology improvements in various fields which make it stand out from other Earth observation satellites. In particular, its best-in-class agility performance enables new calibration and assessment techniques. This paper is dedicated to presenting these innovative techniques that have been tested for the first time for the Pleiades- HR radiometric commissioning. Radiometric activities concern compression, absolute calibration, detector normalization, and refocusing operations, MTF (Modulation Transfer Function) assessment, signal-to-noise ratio (SNR) estimation, and tuning of the ground processing parameters. The radiometric performances of each activity are summarized in this paper.

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

    NASA Astrophysics Data System (ADS)

    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.

  8. 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

  9. 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

  10. Effects of characteristics of image quality in an immersive environment

    NASA Technical Reports Server (NTRS)

    Duh, Henry Been-Lirn; Lin, James J W.; Kenyon, Robert V.; Parker, Donald E.; Furness, Thomas A.

    2002-01-01

    Image quality issues such as field of view (FOV) and resolution are important for evaluating "presence" and simulator sickness (SS) in virtual environments (VEs). This research examined effects on postural stability of varying FOV, image resolution, and scene content in an immersive visual display. Two different scenes (a photograph of a fountain and a simple radial pattern) at two different resolutions were tested using six FOVs (30, 60, 90, 120, 150, and 180 deg.). Both postural stability, recorded by force plates, and subjective difficulty ratings varied as a function of FOV, scene content, and image resolution. Subjects exhibited more balance disturbance and reported more difficulty in maintaining posture in the wide-FOV, high-resolution, and natural scene conditions.

  11. 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) (β=-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 (β=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 (β=-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 (β=-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

  12. Imaging of coronary artery bypass grafts by computed tomography coronary angiography.

    PubMed

    Laspas, Fotios; Roussakis, Arkadios; Kritikos, Nikolaos; Mourmouris, Christos; Efthimiadou, Roxani; Andreou, John

    2013-01-01

    In recent years, computed tomography coronary angiography is commonly performed as a follow-up examination after coronary artery bypass graft surgery. Coronary grafts owing to their minimal motion are well visualized by computed tomography coronary angiography, allowing radiologists to assess their patency noninvasively with very high diagnostic accuracy. The purpose of this pictorial essay is to provide an excellent overview of the anatomy and findings concerning coronary artery bypass grafts. PMID:24159923

  13. A virtual image chain for perceived image quality of medical display

    NASA Astrophysics Data System (ADS)

    Marchessoux, Cédric; Jung, Jürgen

    2006-03-01

    This paper describes a virtual image chain for medical display (project VICTOR: granted in the 5th framework program by European commission). The chain starts from raw data of an image digitizer (CR, DR) or synthetic patterns and covers image enhancement (MUSICA by Agfa) and both display possibilities, hardcopy (film on viewing box) and softcopy (monitor). Key feature of the chain is a complete image wise approach. A first prototype is implemented in an object-oriented software platform. The display chain consists of several modules. Raw images are either taken from scanners (CR-DR) or from a pattern generator, in which characteristics of DR- CR systems are introduced by their MTF and their dose-dependent Poisson noise. The image undergoes image enhancement and comes to display. For soft display, color and monochrome monitors are used in the simulation. The image is down-sampled. The non-linear response of a color monitor is taken into account by the GOG or S-curve model, whereas the Standard Gray-Scale-Display-Function (DICOM) is used for monochrome display. The MTF of the monitor is applied on the image in intensity levels. For hardcopy display, the combination of film, printer, lightbox and viewing condition is modeled. The image is up-sampled and the DICOM-GSDF or a Kanamori Look-Up-Table is applied. An anisotropic model for the MTF of the printer is applied on the image in intensity levels. The density-dependent color (XYZ) of the hardcopy film is introduced by Look-Up-tables. Finally a Human Visual System Model is applied to the intensity images (XYZ in terms of cd/m2) in order to eliminate nonvisible differences. Comparison leads to visible differences, which are quantified by higher order image quality metrics. A specific image viewer is used for the visualization of the intensity image and the visual difference maps.

  14. Evaluation of scatter effects on image quality for breast tomosynthesis

    PubMed Central

    Wu, Gang; Mainprize, James G.; Boone, John M.; Yaffe, Martin J.

    2009-01-01

    Digital breast tomosynthesis uses a limited number (typically 10–20) of low-dose x-ray projections to produce a pseudo-three-dimensional volume tomographic reconstruction of the breast. The purpose of this investigation was to characterize and evaluate the effect of scattered radiation on the image quality for breast tomosynthesis. In a simulation, scatter point spread functions generated by a Monte Carlo simulation method were convolved over the breast projection to estimate the distribution of scatter for each angle of tomosynthesis projection. The results demonstrate that in the absence of scatter reduction techniques, images will be affected by cupping artifacts, and there will be reduced accuracy of attenuation values inferred from the reconstructed images. The effect of x-ray scatter on the contrast, noise, and lesion signal-difference-to-noise ratio (SDNR) in tomosynthesis reconstruction was measured as a function of the tumor size. When a with-scatter reconstruction was compared to one without scatter for a 5 cm compressed breast, the following results were observed. The contrast in the reconstructed central slice image of a tumorlike mass (14 mm in diameter) was reduced by 30%, the voxel value (inferred attenuation coefficient) was reduced by 28%, and the SDNR fell by 60%. The authors have quantified the degree to which scatter degrades the image quality over a wide range of parameters relevant to breast tomosynthesis, including x-ray beam energy, breast thickness, breast diameter, and breast composition. They also demonstrate, though, that even without a scatter rejection device, the contrast and SDNR in the reconstructed tomosynthesis slice are higher than those of conventional mammographic projection images acquired with a grid at an equivalent total exposure. PMID:19928073

  15. A new algorithm for integrated image quality measurement based on wavelet transform and human visual system

    NASA Astrophysics Data System (ADS)

    Wang, Haihui

    2006-01-01

    An essential determinant of the value of digital images is their quality. Over the past years, there have been many attempts to develop models or metrics for image quality that incorporate elements of human visual sensitivity. However, there is no current standard and objective definition of spectral image quality. This paper proposes a reliable automatic method for objective image quality measurement by wavelet transform and Human visual system. This way the proposed measure differentiates between the random and signal-dependant distortion, which have different effects on human observer. Performance of the proposed quality measure is illustrated by examples involving images with different types of degradation. The technique provides a means to relate the quality of an image to the interpretation and quantification throughout the frequency range, in which the noise level is estimated for quality evaluation. The experimental results of using this method for image quality measurement exhibit good correlation to subjective visual quality assessments.

  16. Identifying the arterial input function from dynamic contrast-enhanced magnetic resonance images using an apex-seeking technique

    NASA Astrophysics Data System (ADS)

    Martel, Anne L.

    2004-04-01

    In order to extract quantitative information from dynamic contrast-enhanced MR images (DCE-MRI) it is usually necessary to identify an arterial input function. This is not a trivial problem if there are no major vessels present in the field of view. Most existing techniques rely on operator intervention or use various curve parameters to identify suitable pixels but these are often specific to the anatomical region or the acquisition method used. They also require the signal from several pixels to be averaged in order to improve the signal to noise ratio, however this introduces errors due to partial volume effects. We have described previously how factor analysis can be used to automatically separate arterial and venous components from DCE-MRI studies of the brain but although that method works well for single slice images through the brain when the blood brain barrier technique is intact, it runs into problems for multi-slice images with more complex dynamics. This paper will describe a factor analysis method that is more robust in such situations and is relatively insensitive to the number of physiological components present in the data set. The technique is very similar to that used to identify spectral end-members from multispectral remote sensing images.

  17. Transient left ventricular cavitary dilation during dipyridamole-thallium imaging as an indicator of severe coronary artery disease

    SciTech Connect

    Lette, J.; Lapointe, J.; Waters, D.; Cerino, M.; Picard, M.; Gagnon, A. )

    1990-11-15

    Transient left ventricular (LV) cavitary dilation during dipyridamole-thallium imaging was reported in 45 of 510 (9%) consecutive patients referred for dipyridamole-thallium imaging. Clinical and hemodynamic effects observed during dipyridamole infusion were not predictive of transient cavitary dilation on the thallium images. Coronary angiography was performed in 32 of the 45 patients: 75% had either left main, 3-vessel or high-risk 2-vessel coronary artery disease. Although 25 of 45 patients (56%) with transient cavitary dilation were either asymptomatic or had only grade 1/4 effort angina, 16 of 25 patients (64%) not referred for coronary revascularization sustained a cardiac event during a mean follow-up of 12 months. Most events were cardiac deaths (75%) and 87% of events occurred within 4 months of the test. Noncardiac surgery was performed in 187 of the 510 patients. The postoperative cardiac event rate was 2% in the 101 patients with normal scans or fixed defects, 19% in 75 patients with reversible perfusion defects and 58% in 12 patients with reversible cavitary dilation (p less than 0.0001). Thus, transient LV dilation during dipyridamole-thallium imaging is a marker of severe underlying coronary artery disease, denotes a poor prognosis and predicts a high risk of postoperative cardiac complications in patients who undergo noncardiac surgery.

  18. 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 defa