Sample records for artery image quality

  1. Correlation between low tube voltage in dual source CT coronary artery imaging with image quality and radiation dose.

    PubMed

    Lei, Zi-qiao; Han, Ping; Xu, Hai-bo; Yu, Jian-ming; Liu, Hong-li

    2014-08-01

    The influence of low tube voltage in dual source CT (DSCT) coronary artery imaging on image quality and radiation dose and its application value in clinical practice were investigated. Totally, 300 cases of chest pain with low body mass index (BMI <18.5 kg/m(2)) subjected to DSCT coronary artery imaging were prospectively enrolled. The heart rate in all patients were greater than 65/min. The retrospective ECG gated scanning mode and simple random sampling method were used to assign the patients into groups A, B and C (n=100 each). The patients in groups A, B and C experienced 120-, 100-, and 80-kV tube voltage imaging respectively, and the image quality was evaluated. The CT volume dose index (CTDIvol) and dose length product (DLP) were recorded, and the effective dose (ED) was calculated in each group. The image quality scores and radiation doses in groups were compared, and the influence of tube voltage on image quality and radiation dose was analyzed. The results showed that the excellent rate of image quality in groups A, B and C was 95.69%, 94.72% and 96.33% respectively with the difference being not statistically significant among the three groups (P>0.05). The CTDIvol values in groups A, B and C were 51.35±12.21, 21.28±7.13 and 6.34±3.34 mGy, respectively, with the difference being statistically significant (P<0.05). The ED values in groups A, B and C were 9.27±1.63, 4.56±2.29 and 2.29±1.69 mSv, respectively, with the difference being statistically significant (P<0.05). It was suggested that for the patients with low BMI, the application of DSCT coronary artery imaging with low tube voltage can obtain satisfactory image quality, and simultaneously, significantly reduce the radiation dose. PMID:25135738

  2. Quality evaluation of ultrasound imaging in the carotid artery based on normalization and speckle reduction filtering

    Microsoft Academic Search

    Christos P. Loizou; Constantinos S. Pattichis; Marios Pantziaris; T. Tyllis; Andrew Nicolaides

    2006-01-01

    Image quality is important when evaluating ultrasound images of the carotid for the assessment of the degree of atherosclerotic disease, or when transfer- ring images through a telemedicine channel, and\\/or in other image processing tasks. The objective of this study was to investigate the usefulness of image quality eval- uation based on image quality metrics and visual per- ception, in

  3. Imaging of coronary arteries using synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Thompson, A. C.; Zeman, H.; Thomlinson, W.; Rubenstein, E.; Kernoff, R. S.; Hofstadter, R.; Giacomini, J. C.; Gordon, H. J.; Brown, G. S.

    1989-04-01

    Currently the imaging of coronary arteries is dangerous since it requires that a catheter be inserted into a peripheral artery and threaded up to the heart so that contrast agent can be injected directly into the artery being imaged. Using synchrotron radiation it may be possible to use a much safer venous injection of a contrast agent and still have sufficient image contrast to visualize the coronary arteries. A pair of monochromatized X-ray beams are used which have energies that bracket the iodine K absorption edge where the iodine absorption cross section jumps by a factor of six. Therefore, the logarithmic difference image has excellent sensitivity to contrast agent and minimal sensitivity to tissue and bone. Images have been taken of both dogs and humans. Improvements are being made to the imaging system which will substantially improve the image quality.

  4. Arterial blood sample (image)

    MedlinePLUS

    ... rather than a vein is to measure blood gases. Because arterial blood is oxygenated blood flowing directly from the heart, analysis of arterial blood can determine the chemistry of the blood before it is used by ...

  5. Patient Characteristics as Predictors of Image Quality and Diagnostic Accuracy of MDCT Compared With Conventional Coronary Angiography for Detecting Coronary Artery Stenoses: CORE-64 Multicenter International Trial

    PubMed Central

    Dewey, Marc; Vavere, Andrea L.; Arbab-Zadeh, Armin; Miller, Julie M.; Sara, Leonardo; Cox, Christopher; Gottlieb, Ilan; Yoshioka, Kunihiro; Paul, Narinder; Hoe, John; de Roos, Albert; Lardo, Albert C.; Lima, Joao A.; Clouse, Melvin E.

    2012-01-01

    OBJECTIVE The purpose of the study was to investigate patient characteristics associated with image quality and their impact on the diagnostic accuracy of MDCT for the detection of coronary artery stenosis. MATERIALS AND METHODS Two hundred ninety-one patients with a coronary artery calcification (CAC) score of ? 600 Agatston units (214 men and 77 women; mean age, 59.3 ± 10.0 years [SD]) were analyzed. An overall image quality score was derived using an ordinal scale. The accuracy of quantitative MDCT to detect significant (? 50%) stenoses was assessed using quantitative coronary angiography (QCA) per patient and per vessel using a modified 19-segment model. The effect of CAC, obesity, heart rate, and heart rate variability on image quality and accuracy were evaluated by multiple logistic regression. Image quality and accuracy were further analyzed in subgroups of significant predictor variables. Diagnostic analysis was determined for image quality strata using receiver operating characteristic (ROC) curves. RESULTS Increasing body mass index (BMI) (odds ratio [OR] = 0.89, p < 0.001), increasing heart rate (OR = 0.90, p < 0.001), and the presence of breathing artifact (OR = 4.97, p ? 0.001) were associated with poorer image quality whereas sex, CAC score, and heart rate variability were not. Compared with examinations of white patients, studies of black patients had significantly poorer image quality (OR = 0.58, p = 0.04). At a vessel level, CAC score (10 Agatston units) (OR = 1.03, p = 0.012) and patient age (OR = 1.02, p = 0.04) were significantly associated with the diagnostic accuracy of quantitative MDCT compared with QCA. A trend was observed in differences in the areas under the ROC curves across image quality strata at the vessel level (p = 0.08). CONCLUSION Image quality is significantly associated with patient ethnicity, BMI, mean scan heart rate, and the presence of breathing artifact but not with CAC score at a patient level. At a vessel level, CAC score and age were associated with reduced diagnostic accuracy. PMID:20028910

  6. 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.

  7. 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.

  8. Coronary artery wall imaging.

    PubMed

    Keegan, Jennifer

    2015-05-01

    Like X-Ray contrast angiography, MR coronary angiograms show the vessel lumens rather than the vessels themselves. Consequently, outward remodeling of the vessel wall, which occurs in subclinical coronary disease before luminal narrowing, cannot be seen. The current gold standard for assessing the coronary vessel wall is intravascular ultrasound, and more recently, optical coherence tomography, both of which are invasive and use ionizing radiation. A noninvasive, low-risk technique for assessing the vessel wall would be beneficial to cardiologists interested in the early detection of preclinical disease and for the safe monitoring of the progression or regression of disease in longitudinal studies. In this review article, the current state of the art in MR coronary vessel wall imaging is discussed, together with validation studies and recent developments. J. Magn. Reson. Imaging 2015;41:1190-1202. © 2014 Wiley Periodicals, Inc. PMID:25303707

  9. Location of foot arteries using infrared images

    NASA Astrophysics Data System (ADS)

    Villasenor-Mora, Carlos; González-Vega, Arturo; Martín Osmany Falcón, Antonio; Benítez Ferro, Jesús Francisco Guillemo; Córdova Fraga, Teodoro

    2014-11-01

    In this work are presented the results of localization of foot arteries, in a young group of participants by using infrared thermal images, these are the dorsal, posterior tibial and anterior tibial arteries. No inclusion criteria were considered, that causes that no strong statistical data about the influence of the age in the arterial localization. It was achieved to solve the confusion when veins present a heat distribution similar to the artery and in the position of this. it contributes to enhance the rate of location of arteries. In general it is possible to say that the use of infrared thermal images is a good technique to find the foot arteries and can be applied in its characterization in a future. The procedure proposed is a non-invasive technique, and in certain fashion does not requires specialized personnel to achieve locate the arteries. It is portable, safe, and relatively economical.

  10. 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

  11. 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.

  12. Photoacoustic imaging of carotid artery atherosclerosis.

    PubMed

    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. PMID:25411898

  13. Intraoperative coronary artery imaging with infrared camera in off-pump CABG

    Microsoft Academic Search

    Hisayoshi Suma; Tadashi Isomura; Taiko Horii; Toru Sato

    2000-01-01

    To achieve high quality off-pump coronary artery bypass grafting (CABG), thermal coronary artery imaging using a new generation infrared camera was used and anastomotic status was assessed intraoperatively. In 12 patients who underwent off-pump CABG, 18 grafts (11 internal thoracic, 2 radial, 2 gastroepiploic arteries, and 3 saphenous veins) were evaluated following completion of anastomoses. All grafts were clearly visualized

  14. 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

  15. Segmentation of Retinal Arteries in Adaptive Optics Images

    E-print Network

    Boyer, Edmond

    Segmentation of Retinal Arteries in Adaptive Optics Images Nicolas Lermé, Florence Rossant--In this paper, we present a method for automatically segmenting the walls of retinal arteries in adaptive optics, ap- proximate parallelism, retina imaging. I. INTRODUCTION Arterial hypertension (AH) and diabetic

  16. Segmentation of Retinal Arteries in Adaptive Optics Images

    E-print Network

    Paris-Sud XI, Université de

    Segmentation of Retinal Arteries in Adaptive Optics Images Nicolas Lermé, Florence Rossant for automatically segmenting the walls of retinal arteries in adaptive optics images. To the best of our knowledge. INTRODUCTION The diseases affecting the retinal blood vessels of small diameter ( 150µm) such as arterial

  17. An ultrasonic scanning system for arterial imaging

    NASA Technical Reports Server (NTRS)

    Hottinger, C. F.; Meindl, J. D.

    1973-01-01

    A transcutaneous system for real-time imaging of arteries is described. A transducer probe containing three linear arrays of elements scans tissues within the element Fresnel zones. Each element is multiplexed in turn to a pulsed Doppler processor to permit real-time visualizations of moving targets. Applications of the motion-indicating B-scans are discussed, with special attention to problems in transcutaneous measurement of blood flow.

  18. High-resolution MR imaging of the cervical arterial wall: what the radiologist needs to know.

    PubMed

    Oppenheim, Catherine; Naggara, Olivier; Touzé, Emmanuel; Lacour, Jean-Christophe; Schmitt, Emmanuelle; Bonneville, Fabrice; Crozier, Sophie; Guégan-Massardier, Evelyne; Gerardin, Emmanuel; Leclerc, Xavier; Neau, Jean-Philippe; Sirol, Marc; Toussaint, Jean-François; Mas, Jean-Louis; Méder, Jean-François

    2009-01-01

    The emergence of high-resolution rapid imaging methods has enabled magnetic resonance (MR) imagers to noninvasively image the fine internal structure of cervical arterial walls. In this article, a comprehensive guide to performing high-resolution MR imaging of cervical arteries is provided, including the choice of coils, sequences, and imaging parameters, as well as tips for optimal image quality. Explanations and illustrations are given of using high-resolution MR imaging to quantify plaque volume, determine atherosclerotic plaque burden, depict plaque composition, and ultimately identify unstable plaque before it leads to a clinical event. Finally, the role of high-resolution MR imaging in the diagnosis of cervical dissection and inflammatory disease of the arterial wall is emphasized. PMID:19755603

  19. Tissue Classification of Arterial Wall Based on Elasticity Image

    Microsoft Academic Search

    Jun Inagaki; Hideyuki Hasegawa; Hiroshi Kanai; Masataka Ichiki; Fumiaki Tezuka

    2006-01-01

    The phased tracking method was developed for measuring the minute change in thickness during one cardiac cycle and the elasticity of the arterial wall. By comparing elasticity images measured by the phased tracking method with the corresponding pathological images, the elasticity distribution for each tissue in the arterial wall was determined. We have already measured the elasticity distributions for lipids,

  20. Comprehensive data visualization for high resolution endovascular carotid arterial wall imaging

    NASA Astrophysics Data System (ADS)

    Cheng, Kyle H. Y.; Sun, Cuiru; Cruz, Juan P.; Marotta, Thomas R.; Spears, Julian; Montanera, Walter J.; Thind, Aman; Courtney, Brian; Standish, Beau A.; Yang, Victor X. D.

    2012-05-01

    Carotid angioplasty and stenting is a minimally invasive endovascular procedure that may benefit from in vivo high resolution imaging for monitoring the physical placement of the stent and potential complications. The purpose of this pilot study was to evaluate the ability of optical coherence tomography to construct high resolution 2D and 3D images of stenting in porcine carotid artery. Four Yorkshire pigs were anaesthetized and catheterized. A state-of-the-art optical coherence tomography (OCT) system and an automated injector were used to obtain both healthy and stented porcine carotid artery images. Data obtained were then processed for visualization. The state-of-the-art OCT system was able to capture high resolution images of both healthy and stented carotid arteries. High quality 3D images of healthy and stented carotid arteries were constructed, clearly depicting vessel wall morphological features, stent apposition and thrombus formation over the inserted stent. The results demonstrate that OCT can be used to generate high quality 3D images of carotid arterial stents for accurate diagnosis of stent apposition and complications under appropriate imaging conditions.

  1. 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

  2. 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.

  3. Non-invasive imaging of aberrant right subclavian artery pathologies and aberrant right vertebral artery

    Microsoft Academic Search

    M KARCAALTINCABA; M HALILOGLU; E OZKAN; M KOCAK; D AKINCI; M ARIYUREK

    2009-01-01

    Here, we review the CT and MR angiography findings of aberrant right subclavian and right vertebral arteries, with emphasis on the differences between these structures. In addition, non-invasive imaging findings of aberrant right subclavian artery pathologies, including arteritis, aneurysm and dissection, are discussed.

  4. Image quality with array spectrometers

    Microsoft Academic Search

    Suzanne K. Ramsay Howat; Gillian S. Wright; David Montgomery; Eli I. Atad-Ettedgui

    1994-01-01

    We present data on the image quality achieved with the near IR array spectrometer cooled grating spectrometer 4 (CGS4) on the UK IR telescope (UKIRT) on Mauna Kea. A design spot size of 30 micrometers was specified for CGS4, to maintain acceptable image quality with both the 58 by 62 pixel array with which it is currently equipped and the

  5. Intravascular Optical Imaging Technology for Investigating the Coronary Artery

    PubMed Central

    Suter, Melissa J.; Nadkarni, Seemantini K.; Weisz, Giora; Tanaka, Atsushi; Jaffer, Farouc A.; Bouma, Brett E.; Tearney, Guillermo J.

    2012-01-01

    There is an ever-increasing demand for new imaging methods that can provide additional information about the coronary wall to better characterize and stratify high-risk plaques, and to guide interventional and pharmacologic management of patients with coronary artery disease. While there are a number of imaging modalities that facilitate the assessment of coronary artery pathology, this review paper focuses on intravascular optical imaging modalities that provide information on the microstructural, compositional, biochemical, biomechanical, and molecular features of coronary lesions and stents. The optical imaging modalities discussed include angioscopy, optical coherence tomography, polarization sensitive-optical coherence tomography, laser speckle imaging, near-infrared spectroscopy, time-resolved laser induced fluorescence spectroscopy, Raman spectroscopy, and near-infrared fluorescence molecular imaging. Given the wealth of information that these techniques can provide, optical imaging modalities are poised to play an increasingly significant role in the evaluation of the coronary artery in the future. PMID:21920342

  6. 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

  7. Coronary artery balloon angioplasty - series (image)

    MedlinePLUS

    ... flow through the coronary arteries and to the heart tissue in about 90% of patients and may eliminate the need for coronary artery bypass surgery. The outcome is relief from chest pain symptoms and an improved exercise capacity. In 2 out of 3 cases, the ...

  8. Multislice CT imaging of anomalous coronary arteries

    Microsoft Academic Search

    Heshui Shi; Andrik J. Aschoff; Hans-Juergen Brambs; Martin H. K. Hoffmann

    2004-01-01

    The purpose of the present study was to evaluate the role of 16 multislice computed tomography (MSCT) to identify the origin of anomalous coronary arteries and to confirm their anatomic course in relation to the great vessels. Accuracy of coronary artery disease (CAD) detection was a secondary aim and was tested with conventional angiograms (CA) serving as standard of reference.

  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. 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.

  11. From basilar artery dolichoectasia to basilar artery aneurysm: natural history in images.

    PubMed

    Zis, Panagiotis; Fragkis, Stylianos; Lykouri, Maria; Bageris, Ioannis; Kolovos, Georgios; Angelidakis, Panagiotis; Tavernarakis, Antonios

    2015-05-01

    Dolichoectasia is a medical term used to describe elongated and dilated vessels that follow a tortuous and windy course with frequent loops and curves. We are presenting the natural history in images of a normal basilar artery becoming dolichoectatic, followed by the formation of an aneurysm, over a period of many years, in 60-year-old Caucasian man with a long history of secondary progressive multiple sclerosis and uncontrolled arterial hypertension, who was diagnosed with dolichoectasia of basilar artery in 2008. Although relatively stable at this point, eventually his mobility deteriorated and signs from the cranial nerves, such as trigeminal neuralgia and bilateral palsy of the VI and the VII nerves were added in the clinical picture. In 2014, both computed tomography and magnetic resonance imaging of the brain revealed the formation of an unruptured aneurysm of the basilar artery. PMID:25765208

  12. Automatic Image Quality Control System

    NASA Astrophysics Data System (ADS)

    Ryu, Jee-Youl; Kim, Sung-Woo; Kim, Seung-Un; Ha, Deock-Ho

    A new automatic image quality control system for TFT-LCD (Thin Film Transistor Liquid Crystal Display) applications is proposed. Image quality factors such as gamma adjustment, flicker, brightness, and contrast are enhanced by proposed algorithm and system. Developed system utilizes programmable 6-point matching algorithm with reference gamma curve and automatic power setting algorithm. Proposed system showed significantly reduced gamma adjusting time, reduced flicker, high contrast and much less average gamma error than conventional manual method.

  13. 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

  14. Image quality and entropy masking

    Microsoft Academic Search

    Andrew B. Watson; Robert Borthwick; Mathias Taylor

    Image quality models usually include a mechanism whereby artifacts are masked by the image acting as a background. Scientific study of visual masking has followed two traditions: contrast masking and noise masking, depending primarily on whether the mask is deterministic or random. In the former tradition, masking is explained by a decrease in the effective gain of the early visual

  15. Image quality and entropy masking

    Microsoft Academic Search

    Andrew B. Watson; Robert Borthwick; Mathias Taylor

    1997-01-01

    Image quality models usually include a mechanism whereby artifacts are masked by the image acting as a background. Scientific study of visual masking has followed two traditions: contrast masking and noise masking, depending primarily on whether the mask is deterministic or random. In the former tradition, masking is explained by a decrease in the effective gain of the early visual

  16. 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

  17. Dynamic diffuse optical tomography imaging of peripheral arterial disease.

    PubMed

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

    2012-09-01

    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

  18. 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

  19. Imaging of Dual Ophthalmic Arteries: Identification of the Central Retinal Artery

    PubMed Central

    Louw, Louise; Steyl, Johan; Loggenberg, Eugene

    2014-01-01

    Identification of the origin of the central retinal artery (CRA) is imperative in tailoring angiographic studies to resolve a given clinical problem. A case with dual ophthalmic arteries (OAs), characterized by different origins and distinct branching patterns, is documented for training purposes. Pre-clinical diagnosis of a 9-year-old child who presented with a sharp wire in the left-side eyeball was primarily corneal laceration. For imaging, a selected six-vessel angiographic study with the transfemoral approach was performed. Embolization was not required and the wire could be successfully removed. Right-side OA anatomy was normal, while left-side dual OAs with external carotid artery (ECA) and internal carotid artery (ICA) origins were seen. The case presented with a left-side meningo-ophthalmic artery (M-OA) anomaly via the ECA, marked by a middle meningeal artery (MMA) (origin: Maxillary artery; course: Through foramen spinosum) with normal branches (i.e. anterior and posterior branches), and an OA variant (course: Through superior orbital fissure) with a distinct orbital branching pattern. A smaller OA (origin: ICA; course: Through optic foramen) with a distinct ocular branching pattern presented with the central retinal artery (CRA). The presence of the dual OAs and the M-OA anomaly can be explained by disturbed evolutionary changes of the primitive OA and stapedial artery during development. The surgical interventionist must be aware of dual OAs and M-OA anomalies with branching pattern variations on retinal supply, because of dangerous extracranial–intracranial anastomotic connections. It is of clinical significance that the origin of the CRA from the ICA or ECA must be determined to avoid complications to the vision. PMID:25161809

  20. Additive global cerebral blood flow normalization in arterial spin labeling perfusion imaging

    PubMed Central

    Stewart, Stephanie B.; Koller, Jonathan M.; Campbell, Meghan C.; Perlmutter, Joel S.

    2015-01-01

    To determine how different methods of normalizing for global cerebral blood flow (gCBF) affect image quality and sensitivity to cortical activation, pulsed arterial spin labeling (pASL) scans obtained during a visual task were normalized by either additive or multiplicative normalization of modal gCBF. Normalization by either method increased the statistical significance of cortical activation by a visual stimulus. However, image quality was superior with additive normalization, whether judged by intensity histograms or by reduced variability within gray and white matter. PMID:25802806

  1. Quality of compressed medical images.

    PubMed

    Shiao, Ya-Hui; Chen, Tzong-Jer; Chuang, Keh-Shih; Lin, Cheng-Hsun; Chuang, Chun-Chao

    2007-06-01

    Previous studies have shown that Joint Photographic Experts Group (JPEG) 2000 compression is better than JPEG at higher compression ratio levels. However, some findings revealed that this is not valid at lower levels. In this study, the qualities of compressed medical images in these ratio areas ( approximately 20), including computed radiography, computed tomography head and body, mammographic, and magnetic resonance T1 and T2 images, were estimated using both a pixel-based (peak signal to noise ratio) and two 8 x 8 window-based [Q index and Moran peak ratio (MPR)] metrics. To diminish the effects of blocking artifacts from JPEG, jump windows were used in both window-based metrics. Comparing the image quality indices between jump and sliding windows, the results showed that blocking artifacts were produced from JPEG compression, even at low compression ratios. However, even after the blocking artifacts were omitted in JPEG compressed images, JPEG2000 outperformed JPEG at low compression levels. We found in this study that the image contrast and the average gray level play important roles in image compression and quality evaluation. There were drawbacks in all metrics that we used. In the future, the image gray level and contrast effect should be considered in developing new objective metrics. PMID:17318703

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

    E-print Network

    Development of photoacoustic radar imaging for endoscopy (coronary artery) diagnosis A novel intravascular imager technology of fatty acids in arteries responsible for heart disease and stroke is being and detectors capable of scanning circumferentially (tomographically) the inside of an artery around a full

  3. Imaging Biomarkers for Intra-arterial Stroke Therapy

    PubMed Central

    Berkhemer, Olvert A.; Kamalian, Shervin; González, R. Gilberto; Majoie, Charles B. L. M.; Yoo, Albert J.

    2014-01-01

    Despite high rates of early revascularization with intra-arterial stroke therapy, the clinical efficacy of this approach has not been clearly demonstrated. Neuroimaging biomarkers will be useful in future trials for patient selection and for outcomes evaluation. To identify patients who are likely to benefit from intra-arterial therapy, the combination of vessel imaging, infarct size quantification and degree of neurologic deficit appears critical. Perfusion imaging may be useful in specific circumstances, but requires further validation. For measuring treatment outcomes, surrogate biomarkers that appear suitable are angiographic reperfusion as measured by the modified Thrombolysis in Cerebral Infarction scale and final infarct volume. PMID:24932316

  4. Simultaneous Bilateral Magnetic Resonance Imaging of the Femoral Arteries in Peripheral Arterial Disease Patients

    PubMed Central

    Brown, Ryan; Karmonik, Christof; Brunner, Gerd; Lumsden, Alan; Ballantyne, Christie; Johnson, Shawna; Wang, Yi; Morrisett, Joel

    2013-01-01

    Purpose To image the femoral arteries in peripheral arterial disease (PAD) patients using a bilateral receive coil. Materials and Methods An eight-channel surface coil array for bilateral MRI of the femoral arteries at 3T was constructed and evaluated. Results The bilateral array enabled imaging of a 25-cm segment of the superficial femoral arteries (SFA) from the profunda to the popliteal. The array provided improved the signal-to-noise ratio (SNR) at the periphery and similar SNR in the middle of a phantom compared to three other commercially available coils (4-channel torso, quadrature head, whole body). Multicontrast bilateral images of the in vivo SFA with 1 mm inplane resolution made it possible to directly compare lesions in the index SFA to the corresponding anatomical site in the contralateral vessel without repositioning the patient or coil. A set of bilateral time-of-flight, T1-weighted, T2-weighted, and proton density-weighted images was acquired in a clinically acceptable exam time of ?45 minutes. Conclusion The developed bilateral coil is well suited for monitoring dimensional changes in atherosclerotic lesions of the SFA. PMID:21598344

  5. Fovea based image quality assessment

    NASA Astrophysics Data System (ADS)

    Guo, Anan; Zhao, Debin; Liu, Shaohui; Cao, Guangyao

    2010-07-01

    Humans are the ultimate receivers of the visual information contained in an image, so the reasonable method of image quality assessment (IQA) should follow the properties of the human visual system (HVS). In recent years, IQA methods based on HVS-models are slowly replacing classical schemes, such as mean squared error (MSE) and Peak Signal-to-Noise Ratio (PSNR). IQA-structural similarity (SSIM) regarded as one of the most popular HVS-based methods of full reference IQA has apparent improvements in performance compared with traditional metrics in nature, however, it performs not very well when the images' structure is destroyed seriously or masked by noise. In this paper, a new efficient fovea based structure similarity image quality assessment (FSSIM) is proposed. It enlarges the distortions in the concerned positions adaptively and changes the importances of the three components in SSIM. FSSIM predicts the quality of an image through three steps. First, it computes the luminance, contrast and structure comparison terms; second, it computes the saliency map by extracting the fovea information from the reference image with the features of HVS; third, it pools the above three terms according to the processed saliency map. Finally, a commonly experimental database LIVE IQA is used for evaluating the performance of the FSSIM. Experimental results indicate that the consistency and relevance between FSSIM and mean opinion score (MOS) are both better than SSIM and PSNR clearly.

  6. 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.

  7. Synthetic phased arrays for intraluminal imaging of coronary arteries

    Microsoft Academic Search

    M. O'Donnell; M. J. Eberle; D. N. Stephens; J. L. Litzza; K. San Vicente; B. M. Shapo

    1997-01-01

    A 64-element, high efficiency, ceramic piezoelectric array transducer operating at 20 MHz has been constructed for ultrasonic intraluminal imaging. The array is mounted on the surface of a 1.2 mm diameter catheter appropriate for coronary artery applications. Integrated into the catheter tip is a custom analog chip set permitting complete data capture from the array. That is, on each firing

  8. The Research of Image Quality Assessment Methods

    NASA Astrophysics Data System (ADS)

    Cui, Xiaonan; Shi, Zhiyuan; Lin, Jianan; Huang, Lianfen

    In digital transmission, images may undergo quality degradation due to lossy compression and error-prone channels. Efficient measurement tools are needed to quantify induced distortions and to predict their impact on perceived quality. In this paper, an artifcial neural network (ANN) is proposed for perceptual image quality assessment. The quality prediction is based on image features such as EPSNR, blocking, and blur. Training and testing of the ANN are performed with the mean opinion scores (MOS) provided by the Laboratory for Image and Video Engineering (LIVE). It is shown that the proposed image quality assessment model is capable of predicting MOS of the five types' image distortions.

  9. Strategies for Reducing Respiratory Motion Artifacts in Renal Perfusion Imaging with Arterial Spin Labeling

    PubMed Central

    Robson, Philip M.; Madhuranthakam, Ananth J.; Dai, Weiying; Pedrosa, Ivan; Rofsky, Neil M.; Alsop, David C.

    2010-01-01

    Arterial Spin Labeling (ASL) perfusion measurements may have many applications outside the brain. In the abdomen, severe image-artifacts can arise from motions between acquisitions of multiple signal averages in ASL, even with single-shot image-acquisition. Background suppression and respiratory motion synchronization techniques can be used to ameliorate these artifacts. Two separate in-vivo studies of renal perfusion imaging using pulsed-continuous ASL were performed. The first study assessed various combinations of background suppression and breathing strategies. The second investigated the retrospective sorting of images acquired during free breathing based on respiratory position. Quantitative assessments of the test-retest repeatability of perfusion measurements and the image quality scored by two radiologists were made. Image quality was most significantly improved by using background suppression schemes and controlled breathing when compared to other combinations without background suppression or with free breathing, assessed by test-retests (5% level, F-test), and by radiologists’ scores (5% level, Mann-Whitney U-test). Under free breathing, retrospectively sorting images based on respiratory position showed significant improvement. Both radiologists found 100% of the images had preferable image sharpness after sorting. High quality renal perfusion measurements with reduced respiratory motion artifacts have been demonstrated using ASL when appropriate background suppression and breathing strategies are applied. PMID:19319891

  10. Perceived image quality assessment for color images on mobile displays

    NASA Astrophysics Data System (ADS)

    Jang, Hyesung; Kim, Choon-Woo

    2015-01-01

    With increase in size and resolution of mobile displays and advances in embedded processors for image enhancement, perceived quality of images on mobile displays has been drastically improved. This paper presents a quantitative method to evaluate perceived image quality of color images on mobile displays. Three image quality attributes, colorfulness, contrast and brightness, are chosen to represent perceived image quality. Image quality assessment models are constructed based on results of human visual experiments. In this paper, three phase human visual experiments are designed to achieve credible outcomes while reducing time and resources needed for visual experiments. Values of parameters of image quality assessment models are estimated based on results from human visual experiments. Performances of different image quality assessment models are compared.

  11. 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.

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

    E-print Network

    Greenaway, Alan

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

  13. ACCURATE SEGMENTATION OF ARTERIAL WALLS IN ADAPTIVE OPTICS IMAGES Nicolas Lerm

    E-print Network

    Recanati, Catherine

    ACCURATE SEGMENTATION OF ARTERIAL WALLS IN ADAPTIVE OPTICS IMAGES Nicolas Lermé Florence Rossant Versailles ABSTRACT In this paper, a new approach is presented for accurately de- lineating the artery walls parallelism, retina imaging. 1. INTRODUCTION Arterial hypertension affects the physiology and structure

  14. Imaging of a Renal Artery Aneurysm Detected Incidentally on Ultrasonography

    PubMed Central

    Rafailidis, Vasileios; Gavriilidou, Anna; Liouliakis, Christos; Poultsaki, Maria; Theodoridis, Triantafyllos; Charalampidis, Vasileios

    2014-01-01

    Renal artery aneurysms occur with a frequency of less than 1% of the general population. Even if they are usually asymptomatic and incidentally found, they can be complicated with life-threatening conditions like rupture, thrombosis, embolism, or hypertension. Thus, once diagnosed, they should be fully evaluated with further imaging and treated when indicated. We present the case of a patient who was referred for ultrasonography for an unrelated reason. The examination demonstrated a hyperechoic focus near the right kidney. Further imaging workup with MDCT established the diagnosis of a right renal artery aneurysm which was saccular in shape and peripherally calcified. This ring-like calcification was also visible in a KUB radiography which was also performed. After presenting the case, various aspects of this rare entity are discussed. PMID:24963433

  15. Image quality assessment in the low quality regime

    NASA Astrophysics Data System (ADS)

    Pinto, Guilherme O.; Hemami, Sheila S.

    2012-03-01

    Traditionally, image quality estimators have been designed and optimized to operate over the entire quality range of images in a database, from very low quality to visually lossless. However, if quality estimation is limited to a smaller quality range, their performances drop dramatically, and many image applications only operate over such a smaller range. This paper is concerned with one such range, the low-quality regime, which is defined as the interval of perceived quality scores where there exists a linear relationship between the perceived quality scores and the perceived utility scores and exists at the low-quality end of image databases. Using this definition, this paper describes a subjective experiment to determine the low-quality regime for databases of distorted images that include perceived quality scores but not perceived utility scores, such as CSIQ and LIVE. The performances of several image utility and quality estimators are evaluated in the low-quality regime, indicating that utility estimators can be successfully applied to estimate perceived quality in this regime. Omission of the lowestfrequency image content is shown to be crucial to the performances of both kinds of estimators. Additionally, this paper establishes an upper-bound for the performances of quality estimators in the LQR, using a family of quality estimators based on VIF. The resulting optimal quality estimator indicates that estimating quality in the low-quality regime is robust to exact frequency pooling weights, and that near-optimal performance can be achieved by a variety of estimators providing that they substantially emphasize the appropriate frequency content.

  16. 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

  17. Adaptive fingerprint image enhancement with fingerprint image quality analysis

    E-print Network

    Cho, Sung-Bae

    Adaptive fingerprint image enhancement with fingerprint image quality analysis Eun-Kyung Yun, Sung 20 September 2005; accepted 24 September 2005 Abstract Accurate minutiae extraction from fingerprint images is heavily dependent on the quality of the fingerprint images. In order to improve the performance

  18. Automatic Selection of Mask and Arterial Phase Images for Temporally Resolved MR Digital

    E-print Network

    Zabih, Ramin

    X-ray angiography, where image postprocessing has been used frequently to improve vasculatureAutomatic Selection of Mask and Arterial Phase Images for Temporally Resolved MR Digital for selecting arterial phase images and mask images to generate an optimal sum- mary arteriogram. A paired

  19. Image quality versus statistical power.

    PubMed

    Barnes, A; Dai, D; Montaldi, D; Patterson, J; Wyper, D

    1997-12-01

    We investigated whether SPET studies of neuroactivation might benefit from a similar approach used in PET; that is, increase the number of scans per task and accept poorer individual scan quality. Different study paradigms were simulated by varying the scanning parameters: (1) administered radiation activity per scan, (2) number of scans per task and (3) scan acquisition time. The maximum total dose received by each simulated subject remained the same. Areas of activation of varying signal strength were added to the scans using a customized graphics package. To establish the statistical benefits of a replication paradigm versus a non-replication paradigm, the datasets were analysed using SPM95 statistics software. This simulation was able to show that, when an SPM investigation is used for data analysis, study replication is more important than the individual image quality typically available from a high-performance SPET system. PMID:9481762

  20. Use of intravascular imaging in managing coronary artery disease

    PubMed Central

    Jegere, Sanda; Narbute, Inga; Erglis, Andrejs

    2014-01-01

    For many years, coronary angiography has been considered “the gold standard” for evaluating patients with coronary artery disease. However, angiography only provides a planar two-dimensional silhouette of the lumen and is unsuitable for the precise assessment of atherosclerosis. With the introduction of intravascular imaging, direct visualization of the arterial wall is now feasible. Intravascular imaging modalities extend diagnostic information, thereby enabling more precise evaluation of plaque burden and vessel remodeling. Of all technologies, intravascular ultrasound (IVUS) is the most mature and widely used intravascular imaging technique. Optical coherence tomography (OCT) is an evolving technology that has the highest spatial resolution of existing imaging methods, and it is becoming increasingly widespread. These methods are useful tools for planning interventional strategies and optimizing stent deployment, particularly when stenting complex lesions. We strongly support the mandatory use of IVUS for left main percutaneous coronary intervention (PCI). In addition, it can be used to evaluate vascular responses, including neointimal growth and strut apposition, during follow-ups. Adequately powered randomized trials are needed to support IVUS or OCT use in routine clinical practice and to answer whether OCT is superior to IVUS in reducing adverse events when used to guide PCI. The current perception and adoption of innovative interventional devices, such as bioabsorbable scaffolds, will increase the need for intravascular imaging in the future. PMID:24976911

  1. Combined vector velocity and spectral Doppler imaging for improved imaging of complex blood flow in the carotid arteries.

    PubMed

    Ekroll, Ingvild Kinn; Dahl, Torbjørn; Torp, Hans; Løvstakken, Lasse

    2014-07-01

    Color flow imaging and pulsed wave (PW) Doppler are important diagnostic tools in the examination of patients with carotid artery disease. However, measurement of the true peak systolic velocity is dependent on sample volume placement and the operator's ability to provide an educated guess of the flow direction. Using plane wave transmissions and a duplex imaging scheme, we present an all-in-one modality that provides both vector velocity and spectral Doppler imaging from one acquisition, in addition to separate B-mode images of sufficient quality. The vector Doppler information was used to provide automatically calibrated (angle-corrected) PW Doppler spectra at every image point. It was demonstrated that the combined information can be used to generate spatial maps of the peak systolic velocity, highlighting regions of high velocity and the extent of the stenotic region, which could be used to automate work flow as well as improve the accuracy of measurement of true peak systolic velocity. The modality was tested in a small group (N = 12) of patients with carotid artery disease. PW Doppler, vector velocity and B-mode images could successfully be obtained from a single recording for all patients with a body mass index ranging from 21 to 31 and a carotid depth ranging from 16 to 28 mm. PMID:24785436

  2. Health-related quality of life in patients with pulmonary arterial hypertension

    Microsoft Academic Search

    Darren B Taichman; Jennifer Shin; Laryssa Hud; Christine Archer-Chicko; Sandra Kaplan; Jeffery S Sager; Robert Gallop; Jason Christie; John Hansen-Flaschen; Harold Palevsky

    2005-01-01

    BACKGROUND: Improved outcomes with expanding treatment options for patients with pulmonary arterial hypertension present the opportunity to consider additional end-points in approaching therapy, including factors that influence health-related quality of life. However, comparatively little is known about health-related quality of life and its determinants in patients with pulmonary arterial hypertension. METHODS: Health-related quality of life was evaluated in a cross

  3. Characterization of endothelial function in the brachial artery via affine registration of ultrasonographic image sequences

    NASA Astrophysics Data System (ADS)

    Lamata, Pablo; Laclaustra, Martin; Frangi, Alejandro F.

    2003-05-01

    The assessment and characterization of the endothelial function is a current research topic as it may play an important role in the diagnosis of cardiovascular diseases. Flow mediated dilatation may be used to investigate endothelial function, and B-mode ultrasonography is a cheap and non-invasive way to assess the vasodilation response. Computerized analysis techniques are very desirable to give higher accuracy and objectivity to the measurements. A new method is presented that solves some limitations of existing methods, which in general depend on accurate edge detection of the arterial wall. This method is based on a global image analysis strategy. The arterial vasodilation between two frames is modeled by a superposition of a rigid motion model and a stretching perpendicular to the artery. Both transformation models are recovered using an image registration algorithm based on normalized mutual information and a multi-resolution search framework. Temporal continuity of in the variation of the registration parameters is enforced with a Kalman filter, since the dilation process is known to be a gradual and continuous physiological phenomenon. The proposed method presents a negligible bias when compared with manual assessment. It also eliminates artifacts introduced by patient and probe motion, thus improving the accuracy of the measurements. Finally, it is also robust to typical problems of ultrasound, like speckle noise and poor image quality.

  4. Improved MR images of arterial specimens by submersion in trichlorotrifluoroethane.

    PubMed

    Chu, K C; Martin, A J; Rutt, B K

    1996-05-01

    MR images of ex vivo arterial specimens immersed in 1,1,2-trichloro-1,2,2-trifluoroethane (R-113) have improved signal-to-noise ratio and contrast-to-noise ratio. R-113 has no hydrogen atoms, so it yields no proton signal; hence, the contrast between the specimen and its background is maximized. SNR is maximized because (i) R-113 is nonconductive so that coil loading and inductive noise are minimized, and (ii) the volume susceptibility of R-113 closely matches that of water and tissue so that T2* effects are minimized. Short-term submersion of porcine aortas in R-113 was found to have no significant effect on the artery's hydration level, relaxation time, tensile strength, and structure or quantity of elastin, collagen, or smooth muscle cells. PMID:8722832

  5. 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. [Medical Ultrasound Physics and Technology Group, School of Physics, Dublin Institute of Technology, Dublin 8 (Ireland); Centre for Advanced Medical Imaging (CAMI), St James's Hospital, Dublin 8 (Ireland); Department of Medical Physics, University of Edinburgh, Edinburgh EH16 4TJ (United Kingdom); Medical Ultrasound Physics and Technology Group, School of Physics, Dublin Institute of Technology, Dublin 8 (Ireland)

    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.

  6. Quality Metrics Evaluation of Hyperspectral Images

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  7. 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?image quality of the JJ2000 and Apollo algorithms is statistically equivalent for medical image compression. PMID:23589187

  8. Automatically improving image quality using tensor voting

    Microsoft Academic Search

    Toan Dinh Nguyen; Jonghyun Park; Soohyung Kim; Gueesang Lee

    A novel corrupted region detection technique based on tensor voting is proposed to automatically improve the image quality.\\u000a This method is suitable for restoring degraded images and enhancing binary images. First, the input images are converted into\\u000a layered images in which each layer contains objects having similar characteristics. By encoding the pixels in the layered\\u000a images with second-order tensors and

  9. Segmentation of arteries in MPRAGE images of the ventral medial prefrontal cortex

    PubMed Central

    Penumetcha, N.; Jedynak, B.; Hosakere, M.; Ceyhan, E.; Botteron, K.N.; Ratnanather, J.T.

    2010-01-01

    A method for removing arteries that appear bright with intensities similar to white matter in Magnetized Prepared Rapid Gradient Echo images of the ventral medial prefrontal cortex is described. The fast marching method is used to generate a curve within the artery. Then, the largest connected component is selected to segment the artery which is used to mask the image. The surface reconstructed from the masked image yielded cortical thickness maps similar to those generated by manually pruning the arteries from surfaces reconstructed from the original image. The method may be useful in masking vasculature in other cortical regions. PMID:17964757

  10. Novel image quality metric based on similarity

    Microsoft Academic Search

    Lina Jin; Nikolay Ponomarenko; Karen Egiazarian

    2011-01-01

    In this paper, we present a novel approach to image quality metric taking into account degradation of contrast and brightness as well as block similarity. The metric is achieved by performing of the following steps: 1) reducing contrast and brightness in distorted image, 2) using block-matching (BM) to group similar 2D image fragments into 3D data arrays in original image

  11. 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

  12. 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.

  13. Quality of Life in Women with Coronary Artery Disease

    PubMed Central

    Ghasemi, Elham; Mohammad Aliha, Jaleh; Bastani, Farideh; Haghani, Hamid; Samiei, Niloufar

    2014-01-01

    Background: Coronary artery disease (CAD) as a chronic disease can affect physical, mental, and social aspects of health as well as the perception of wellbeing. Advanced treatments of the disease emphasize on functionality and quality of life (QOL). Objectives: The present study aimed to investigate the QOL and its related factors among women with CAD. Patients and Methods: This was a descriptive cross-sectional study conducted on 200 women with CAD, referring to the Heart Clinic of Shahid Rajaei Cardiovascular Center in Tehran, Iran. The participants were selected by convenient sampling method. Data were collected using the Persian version of Ferrans and Powers QOL index (QLI) cardiac version and then analyzed using descriptive statistics and statistical tests (independent t-test, one-way ANOVA, and Scheffe’s test). Results: The mean score of overall QOL was 16.91 ± 3.54, ranging between 7.17-27.63. Regarding the instrument subscales, the mean scores were as follows: health and functioning: 15.48 ± 4.32, social and economic: 16.18 ± 3.65, psychological/spiritual: 18.04 ± 4.36, and familial: 20.12 ± 4.57. There was a significant relationship between QOL and marital status (P = 0.004), education (P = 0.007), income (P < 0.001) and disease duration (P = 0.047). However, there was no significant association between QOL and age, job and comorbidity. Conclusions: Based on the findings, participants had average levels of overall QOL. Some domains showed the need to improve QOL of women with CAD. Results of the present study revealed the necessity of designing and performing educational and supportive interventions to improve the QOL in women with CAD, especially among patients with low socio-economic status. PMID:25237559

  14. Arterial Spin Labeled MRI Perfusion Imaging: Clinical Applications

    PubMed Central

    Pollock, Jeffrey M.; Tan, Huan; Kraft, Robert A.; Whitlow, Christopher T.; Burdette, Jonathan H.; Maldjian, Joseph A.

    2009-01-01

    Synopsis Arterial spin labeling (ASL) will soon be available as a routine clinical perfusion imaging sequence for a significant number of MRI scanners. The ASL perfusion technique offers similar information as conventional dynamic susceptibility sequences; however, it does not require intravenous contrast and can be quantified. The appearance of pathology is significantly impacted by the ASL techniques used. Familiarity with the available sequence parameter options and the common appearances of pathology will facilitate perfusion interpretation. At Wake Forest University School of Medicine, we have implemented an automated processing pipeline capable of handling a substantial clinical volume of perfusion acquisitions. Over the past 2 years over 8,000 clinical ASL examinations have been performed. These cases have revealed many pathologic and physiologic processes readily identified with quantitative perfusion imaging(1-11). PMID:19406361

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

    PubMed Central

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

    2013-01-01

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

  16. 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.

  17. 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

  18. Seven challenges for image quality research

    NASA Astrophysics Data System (ADS)

    Chandler, Damon M.; Alam, Md M.; Phan, Thien D.

    2014-02-01

    Image quality assessment has been a topic of recent intense research due to its usefulness in a wide variety of applications. Owing in large part to efforts within the HVEI community, image-quality research has particularly benefited from improved models of visual perception. However, over the last decade, research in image quality has largely shifted from the previous broader objective of gaining a better understanding of human vision, to the current limited objective of better fitting the available ground-truth data. In this paper, we discuss seven open challenges in image quality research. These challenges stem from lack of complete perceptual models for: natural images; suprathreshold distortions; interactions between distortions and images; images containing multiple and nontraditional distortions; and images containing enhancements. We also discuss challenges related to computational efficiency. The objective of this paper is not only to highlight the limitations in our current knowledge of image quality, but to also emphasize the need for additional fundamental research in quality perception.

  19. Construction of Reference Data for Tissue Characterization of Arterial Wall Based on Elasticity Images

    Microsoft Academic Search

    Jun Inagaki; Hideyuki Hasegawa; Hiroshi Kanai; Masataka Ichiki; Fumiaki Tezuka

    2005-01-01

    Previously, we developed the phased tracking method [H. Kanai et al.: IEEE Trans. Ultrason. Ferroelectr. Freq. Control 43 (1996) 791] for measuring the minute change in thickness during one heartbeat and the elasticity of the arterial wall. By comparing pathological images with elasticity images measured with ultrasound, elasticity distributions for respective tissues in the arterial wall were determined. We have

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

    NASA Astrophysics Data System (ADS)

    Kondermann, Claudia; Kondermann, Daniel; Yan, Michelle

    2007-03-01

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

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

    E-print Network

    Farag, Aly A.

    electrically. Doppler ultrasound and arterial tonometry are traditional approaches to track the hemodynamics a superficial artery by the measurement of heat variations on the skin surrounding the artery. Passive thermal of the limitations of their approach is the manual selection of the skin segment to be used for the heart rate

  2. Sexual quality of life in patients undergoing coronary artery bypass graft surgery

    Microsoft Academic Search

    Jennifer Barsky Reese; Rebecca A. Shelby; Kathryn L. Taylor

    2011-01-01

    Objectives: Despite improvements in many domains of functioning, sexual quality of life often remains impaired following coronary artery bypass graft (CABG) surgery. This study examined associations among sexual quality of life, fear of sexual activity and receiving information from providers about sexual activity in CABG patients.Methods: Participants completed a survey assessing sexual activity, mental health and physical health at baseline

  3. Sexual quality of life in patients undergoing coronary artery bypass graft surgery

    Microsoft Academic Search

    Jennifer Barsky Reese; Rebecca A. Shelby; Kathryn L. Taylor

    2012-01-01

    Objectives: Despite improvements in many domains of functioning, sexual quality of life often remains impaired following coronary artery bypass graft (CABG) surgery. This study examined associations among sexual quality of life, fear of sexual activity and receiving information from providers about sexual activity in CABG patients.Methods: Participants completed a survey assessing sexual activity, mental health and physical health at baseline

  4. Optimization of background suppression for arterial spin labeling perfusion imaging

    PubMed Central

    Maleki, Nasim; Dai, Weiying; Alsop, David C.

    2013-01-01

    Object To present an algorithm for optimization of background suppression pulse timing for arterial spin labeling (ASL) perfusion imaging. Materials and methods An algorithm for optimization of background suppression pulse timing is proposed. Numerical optimization of timing of the background suppression pulses is investigated in both constrained and unconstrained ASL sequences. The performance of the parameters from the algorithm is evaluated in phantom and also in vivo in five human subjects. Results The background signal is suppressed to less than 1% across a broad range of T1s with a modest number of inversion pulses using the timings acquired from the numerical optimization algorithm proposed in this study. The performance of the parameters from the algorithm is also confirmed in vivo. Conclusion Successful background suppression over a broad range of tissues is achievable. Values for optimal pulse timing in both pulsed and continuous ASL studies are reported to facilitate sequence design with different labeling parameters. PMID:22009131

  5. 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

  6. 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.

  7. 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.

  8. Continuous assessment of perceptual image quality

    NASA Astrophysics Data System (ADS)

    Hamberg, Roelof; de Ridder, Huib

    1995-12-01

    The study addresses whether subjects are able to assess the perceived quality of an image sequence continuously. To this end, a new method for assessing time-varying perceptual image quality is presented by which subjects continuously indicate the perceived strength of image quality by moving a slider along a graphical scale. The slider's position on this scale is sampled every second. In this way, temporal variations in quality can be monitored quantitatively, and a means is provided by which differences between, for example, alternative transmission systems can be analyzed in an informative way. The usability of this method is illustrated by an experiment in which, for a period of 815 s, subjects assessed the quality of still pictures comprising time-varying degrees of sharpness. Copyright (c) 1995 Optical Society of America

  9. Propagation, structural similarity, and image quality

    NASA Astrophysics Data System (ADS)

    Pérez, Jorge; Mas, David; Espinosa, Julián; Vázquez, Carmen; Illueca, Carlos

    2012-06-01

    Retinal image quality is usually analysed through different parameters typical from instrumental optics, i.e, PSF, MTF and wavefront aberrations. Although these parameters are important, they are hard to translate to visual quality parameters since human vision exhibits some tolerance to certain aberrations. This is particularly important in postsurgery eyes, where non-common aberration are induced and their effects on the final image quality is not clear. Natural images usually show a strong dependency between one point and its neighbourhood. This fact helps to the image interpretation and should be considered when determining the final image quality. The aim of this work is to propose an objective index which allows comparing natural images on the retina and, from them, to obtain relevant information abut the visual quality of a particular subject. To this end, we propose a individual eye modelling. The morphological data of the subject's eye are considered and the light propagation through the ocular media is calculated by means of a Fourier-transform-based method. The retinal PSF so obtained is convolved with the natural scene under consideration and the obtained image is compared with the ideal one by using the structural similarity index. The technique is applied on 2 eyes with a multifocal corneal profile (PresbyLasik) and can be used to determine the real extension of the achieved pseudoaccomodation.

  10. Perceptual image quality and telescope performance ranking

    Microsoft Academic Search

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

    2010-01-01

    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

  11. No training blind image quality assessment

    NASA Astrophysics Data System (ADS)

    Chu, Ying; Mou, Xuanqin; Ji, Zhen

    2014-03-01

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

  12. 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 ?m) 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.

  13. 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.

  14. 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.

  15. 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.

  16. Image quality of optical remote sensing data

    NASA Astrophysics Data System (ADS)

    Reulke, Ralf; Säuberlich, Thomas

    2014-10-01

    Photogrammetry and remote sensing (RS) provide procedures for deriving geometric, radiometric and thematic information from image data. A variety of aircraft and space-borne sensors are available to capture image data. Different standards and specifications of quality assessment for optical remote sensing data are available. Due to the possibilities of absolute geometric and radiometric calibration digital sensors provide new promising opportunities to create value added products like digital elevation models, land-use maps etc. Such cameras combine the high geometric quality with the radiometric standards of earth observation systems. The determination of image quality of remote sensing data can be distinguished in (spectral) radiometric and geometric aspects. Standards contains different metrics for accuracy issues (spectral, radiometric and geometric accuracy) and for performance parameters like SNR, MTF. Image artefacts (caused e.g. by compression) are an additional important topic. The paper gives an overview of the current debate and the possibility of standardization.

  17. Cross-Sectional Elastic Imaging of Arterial Wall Using Intravascular Ultrasonography

    Microsoft Academic Search

    Hitoshi Mita; Hiroshi Kanai; Yoshiro Koiwa; Masataka Ichiki; Fumiaki Tezuka

    2001-01-01

    There have been several studies on the imaging of the distribution of the elasticity of the arterial wall using intravascular ultrasonography (IVUS). In those studies, the elasticity is estimated only during ventricular diastole. However, the viscous characteristics of the smooth muscle in the media of the arterial wall are also included in the strain measured during diastole. Alternatively, during systole,

  18. Evaluation of DSA Image Quality

    NASA Astrophysics Data System (ADS)

    Wenstrup, Robert S.

    1985-09-01

    Purchase of a digital subtraction angiography (DSA) system involves medical, financial, and technical considerations. The Lahey Clinic DSA phantoms were developed to assist in technical evaluation of DSA equipment by providing a noninvasive means of assessment of radiographic and digital equipment components before purchase. The same set of phantoms can also be used to assess performance of a. system at the time of installation and for routine evaluation. The critical components of a DSA system are detailed with special emphasis on the image intensifier and television camera. Individual phantom patterns are described, and images are presented.

  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. 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.

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

    SciTech Connect

    Apitzsch, Jonas, E-mail: apitzsch@rad.rwth-aachen.d [RWTH Aachen University, Department of Diagnostic Radiology (Germany); Kuehl, Harald P. [RWTH Aachen University, Department of Cardiology (Germany); Muehlenbruch, Georg; Mahnken, Andreas H. [RWTH Aachen University, Department of Diagnostic Radiology (Germany)

    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.

  2. Characterization of the image-derived carotid artery input function using independent component analysis for the

    E-print Network

    Renaut, Rosemary

    -derived input function by ICA for FDG-PET K Chen1,3,8 , X Chen2 , R Renaut3,5,8 , G E Alexander4,8 , D Bandy1) positron emission tomography (PET) images using an image- derived input function obtained from a manually1 Characterization of the image-derived carotid artery input function using independent component

  3. Impact of waiting time on the quality of life of patients awaiting coronary artery bypass grafting

    Microsoft Academic Search

    John Sampalis; Stella Boukas; Moishe Liberman; Tracey Reid; Gilles Dupuis

    Background: A lack of resources has created waiting lists for many elective surgical procedures within Canada's universal health care system. Coronary artery by- pass grafting (CABG) for the treatment of atherosclerotic ischemic heart disease is one of these affected surgical procedures. We studied the impact of waiting times on the quality of life of patients awaiting CABG. Methods: A prospective

  4. Quality of Life and Coping Following Minimally Invasive Direct Coronary Artery Bypass (MIDCAB) Surgery

    Microsoft Academic Search

    J. Wray; S. Al-Ruzzeh; W. Mazrani; K. Nakamura; S. George; C. Ilsley; M. Amrani

    2004-01-01

    Minimally invasive direct coronary artery bypass (MIDCAB) surgery has been shown to be a promising technique for surgical treatment of single or double vessel disease. However, little is known about quality of life, mood state or coping in this group of patients. The records of 55 consecutive patients who underwent MIDCAB surgery at Harefield Hospital between April 1999 and May

  5. Automating Image Enhancement Optimization Using Image Quality Metrics

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  6. Blind image quality assessment without training on human opinion scores

    NASA Astrophysics Data System (ADS)

    Mittal, Anish; Soundararajan, Rajiv; Muralidhar, Gautam S.; Bovik, Alan C.; Ghosh, Joydeep

    2013-03-01

    We propose a family of image quality assessment (IQA) models based on natural scene statistics (NSS), that can predict the subjective quality of a distorted image without reference to a corresponding distortionless image, and without any training results on human opinion scores of distorted images. These `completely blind' models compete well with standard non-blind image quality indices in terms of subjective predictive performance when tested on the large publicly available `LIVE' Image Quality database.

  7. Monotonic correlation analysis of image quality measures for image fusion

    NASA Astrophysics Data System (ADS)

    Kaplan, Lance M.; Burks, Stephen D.; Moore, Richard K.; Nguyen, Quang

    2008-04-01

    The next generation of night vision goggles will fuse image intensified and long wave infra-red to create a hybrid image that will enable soldiers to better interpret their surroundings during nighttime missions. Paramount to the development of such goggles is the exploitation of image quality (IQ) measures to automatically determine the best image fusion algorithm for a particular task. This work introduces a novel monotonic correlation coefficient to investigate how well possible IQ features correlate to actual human performance, which is measured by a perception study. The paper will demonstrate how monotonic correlation can identify worthy features that could be overlooked by traditional correlation values.

  8. Guides to Quality in Visual Resource Imaging

    NSDL National Science Digital Library

    On July 17, the Research Libraries Group (RLG), Digital Libraries Federation (DLF), and the Council on Library and Information Resources announced a new set of five guides to the technical and planning aspects of digital imaging of visual resources. As the official press release notes, "this new Web-based reference is designed to serve the growing community of museums, archives, and research libraries that are turning to digital conversion to provide greater access to their visual resources as well as to help preserve the original materials." The guides include "Planning a Digital Imaging Project"; "Selecting a Scanner"; "Imaging Systems: the Range of Factors Affecting Image Quality"; "Measuring Quality of Digital Masters"; and "File Formats for Digital Masters." All are offered in HTML format, and users's comments are encouraged for future updates.

  9. Preoperative visualization of the marginal tentorial artery as an unusual collateral pathway in a patient with symptomatic bilateral vertebral artery occlusion undergoing arterial bypass surgery: A 7.0-T magnetic resonance imaging study

    PubMed Central

    Sato, Yuiko; Ogasawara, Kuniaki; Yoshida, Kenji; Sasaki, Makoto

    2014-01-01

    Background: Extracranial–intracranial arterial bypass surgery is rarely performed for recurrent or progressing stroke due to vertebrobasilar artery steno-occlusive disease. Non-enhanced 7.0-T magnetic resonance (MR) imaging reveals cerebral arteries more clearly than 3.0-T or less MR imaging. Case Description: A 45-year-old man developed recurrent transient ischemic attacks due to hemodynamic ischemia caused by occlusion of bilateral vertebral arteries despite antiplatelet therapy. MR angiography with a 7.0-T imager demonstrated that each marginal tentorial artery ran along the tentorial edge and anastomosed with each posterior cerebral artery (PCA) as collateral circulation. Superficial temporal artery (STA)–superior cerebellar artery (SCA) or PCA bypass surgery was planned through a subtemporal approach. During surgery, the SCA was not visible when the tentorial edge was elevated. The tentorium was not cut, and the STA was anastomosed with the P2 segment of the PCA. Ischemic symptoms completely resolved after surgery. Conclusions: Preoperative 7.0-T MR imaging visualized the marginal tentorial artery as an unusual collateral pathway in a patient with symptomatic bilateral vertebral artery occlusion undergoing arterial bypass surgery. PMID:25422785

  10. Color Doppler flow imaging of the facial artery and vein.

    PubMed

    Zhao, Z; Li, S; Xu, J; Li, Y; Huang, W; Yang, M; Mu, L; Liu, Y; Zhai, H; Jin, J; Li, J; Li, J; Fu, X

    2000-11-01

    The purpose of this study was to provide some guidelines with respect to the location of the facial vessels, display the potential inverted blood flow of the facial artery, and reemphasize the value of color Doppler ultrasound studies in flap planning. An anatomic study of the facial artery and vein was done using color Doppler ultrasonography in 12 adults. The artery and the vein were located together at the lower border of the mandible. Around the oral commissure and under the nasal ala, they were located apart from each other with variable distances. This divergence of the facial vein from the artery is important information in the planning of axial pattern flaps. Furthermore, the reverse flow was observed in 12 patients after the blood flow of the facial artery was stopped by applying pressure manually at the lower border of the mandible. Observation of the reversed flow confirms the possibility of safe elevation of a retrograde flow-arterialized flap based on the distal portion of the facial artery. PMID:11083553

  11. 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.

  12. 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.

  13. Multimodality Imaging of Left Circumflex Artery to Coronary Sinus Fistula

    PubMed Central

    Sze, Tan Ling; Abdul Aziz, Yang Faridah; Abu Bakar, Norzailin; Mohd Sani, Fadhli; Oemar, Hamid

    2015-01-01

    Coronary artery fistula (CAF) is a rare anomaly of the coronary artery. Patients with this condition are usually asymptomatic. However, cardiac failure may occur later in life due to progressive enlargement of the fistula. Diagnosis is traditionally made by echocardiogram and conventional angiogram. However with the advantage of new technologies such as computed tomography (CT) coronary angiography, the course and communications of these fistulae can be delineated non-invasively and with greater accuracy. We report a case of a left circumflex artery fistula to the coronary sinus which was suspected on echocardiogram and the diagnosis was clinched on ECG-gated CT. PMID:25793089

  14. 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.

  15. Does resolution really increase image quality?

    NASA Astrophysics Data System (ADS)

    Tisse, Christel-Loïc; Guichard, Frédéric; Cao, Frédéric

    2008-02-01

    A general trend in the CMOS image sensor market is for increasing resolution (by having a larger number of pixels) while keeping a small form factor by shrinking photosite size. This article discusses the impact of this trend on some of the main attributes of image quality. The first example is image sharpness. A smaller pitch theoretically allows a larger limiting resolution which is derived from the Modulation Transfer Function (MTF). But recent sensor technologies (1.75?m, and soon 1.45?m) with typical aperture f/2.8 are clearly reaching the size of the diffraction blur spot. A second example is the impact on pixel light sensitivity and image sensor noise. For photonic noise, the Signal-to-Noise-Ratio (SNR) is typically a decreasing function of the resolution. To evaluate whether shrinking pixel size could be beneficial to the image quality, the tradeoff between spatial resolution and light sensitivity is examined by comparing the image information capacity of sensors with varying pixel size. A theoretical analysis that takes into consideration measured and predictive models of pixel performance degradation and improvement associated with CMOS imager technology scaling, is presented. This analysis is completed by a benchmarking of recent commercial sensors with different pixel technologies.

  16. 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)

  17. 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...

  18. Predicting image quality using a modular image difference model

    NASA Astrophysics Data System (ADS)

    Orfanidou, M.; Triantaphillidou, S.; Allen, E.

    2008-01-01

    The paper is focused on the implementation of a modular color image difference model, as described in [1], with aim to predict visual magnitudes between pairs of uncompressed images and images compressed using lossy JPEG and JPEG 2000. The work involved programming each pre-processing step, processing each image file and deriving the error map, which was further reduced to a single metric. Three contrast sensitivity function implementations were tested; a Laplacian filter was implemented for spatial localization and the contrast masked-based local contrast enhancement method, suggested by Moroney, was used for local contrast detection. The error map was derived using the CIEDE2000 color difference formula on a pixel-by-pixel basis. A final single value was obtained by calculating the median value of the error map. This metric was finally tested against relative quality differences between original and compressed images, derived from psychophysical investigations on the same dataset. The outcomes revealed a grouping of images which was attributed to correlations between the busyness of the test scenes (defined as image property indicating the presence or absence of high frequencies) and different clustered results. In conclusion, a method for accounting for the amount of detail in test is required for a more accurate prediction of image quality.

  19. Image quality assessment based on edge

    NASA Astrophysics Data System (ADS)

    Mou, Xuanqin; Zhang, Min; Xue, Wufeng; Zhang, Lei

    2011-01-01

    The research on image quality assessment (IQA) has been become a hot topic in most area concerning image processing. Seeking for the efficient IQA model with the neurophysiology support is naturally the goal people put the efforts to pursue. In this paper, we argue that comparing the edges position of reference and distorted image can well measure the image structural distortion and become an efficient IQA metric, while the edge is detected from the primitive structures of image convolving with LOG filters. The proposed metric is called NSER that has been designed following a simple logic based on the cosine distance of the primitive structures and two accessible improvements. Validation is taken by comparison of the well-known state-of-the-art IQA metrics: VIF, MS-SSIM, VSNR over the six IQA databases: LIVE, TID2008, MICT, IVC, A57, and CSIQ. Experiments show that NSER works stably across all the six databases and achieves the good performance.

  20. When high-quality face images match poorly

    Microsoft Academic Search

    J. Ross Beveridge; P. Jonathon Phillips; Geof H. Givens; Bruce A. Draper; Mohammad Nayeem Teli; David S. Bolme

    2011-01-01

    In face recognition, quality is typically thought of as a property of individual images, not image pairs. The implicit assumption is that high-quality images should be easy to match to each other, while low quality images should be hard to match. This paper presents a relational graph-based evaluation technique that uses match scores produced by face recognition algorithms to determine

  1. 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.

  2. Model Observers for Assessment of Image Quality

    NASA Astrophysics Data System (ADS)

    Barrett, Harrison H.; Yao, Jie; Rolland, Jannick P.; Myers, Kyle J.

    1993-11-01

    Image quality can be defined objectively in terms of the performance of some "observer" (either a human or a mathematical model) for some task of practical interest. If the end user of the image will be a human, model observers are used to predict the task performance of the human, as measured by psychophysical studies, and hence to serve as the basis for optimization of image quality. In this paper, we consider the task of detection of a weak signal in a noisy image. The mathematical observers considered include the ideal Bayesian, the nonprewhitening matched filter, a model based on lineardiscriminant analysis and referred to as the Hotelling observer, and the Hotelling and Bayesian observers modified to account for the spatial-frequency-selective channels in the human visual system. The theory behind these observer models is briefly reviewed, and several psychophysical studies relating to the choice among them are summarized. Only the Hotelling model with channels is mathematically tractable in all cases considered here and capable of accounting for all of these data. This model requires no adjustment of parameters to fit the data and is relatively insensitive to the details of the channel mechanism. We therefore suggest it as a useful model observer for the purpose of assessing and optimizing image quality with respect to simple detection tasks.

  3. A registration-based approach to quantify flow-mediated dilation (FMD) of the brachial artery in ultrasound image sequences.

    PubMed

    Frangi, Alejandro F; Laclaustra, Martín; Lamata, Pablo

    2003-11-01

    Flow-mediated dilation (FMD) offers a mechanism to characterize endothelial function and, therefore, may play a role in the diagnosis of cardiovascular diseases. Computerized analysis techniques are very desirable to give accuracy and objectivity to the measurements. Virtually all methods proposed up to now to measure FMD rely on accurate edge detection of the arterial wall, and they are not always robust in the presence of poor image quality or image artifacts. A novel method for automatic dilation assessment based on a global image analysis strategy is presented. We model interframe arterial dilation as a superposition of a rigid motion and a scaling factor perpendicular to the artery. Rigid motion can be interpreted as a global compensation for patient and probe movements, an aspect that has not been sufficiently studied before. The scaling factor explains arterial dilation. The ultrasound sequence is analyzed in two phases using image registration to recover both transformation models. Temporal continuity in the registration parameters along the sequence is enforced with a Kalman filter since the dilation process is known to be a gradual physiological phenomenon. Comparing automated and gold standard measurements (average of manual measurements) we found a negligible bias (0.05%FMD) and a small standard deviation (SD) of the differences (1.05%FMD). These values are comparable with those obtained from manual measurements (bias = 0.23%FMD, SD(intra-obs) = 1.13%FMD, SD(inter-obs) 1.20%FMD). The proposed method offers also better reproducibility (CV = 0.40%) than the manual measurements (CV = 1.04%). PMID:14606679

  4. Image quality assessment using contourlet transform

    NASA Astrophysics Data System (ADS)

    Liu, Mingna; Yang, Xin

    2009-10-01

    We present a novel objective full-reference image quality assessment metric based on multiscale geometric analysis. The multichannel behavior of the human vision system is emulated by contourlet transform, a perceptual subband decomposition. Not only the contrast-masking effect but also the entropy-masking effect is considered to deal with the visual masking issue. In the error pooling stage, the frequency sensitivity of the HVS is investigated. Nonlinear and linear fusion schemes of subband distortion are compared. Extensive validation experiments are performed on two professional image databases, the LIVE database supplied by the University of Texas and the A57 database supplied by Cornell University. Compared with several state-of-the-art image quality metrics, the proposed metric demonstrates improvement on prediction accuracy and robustness.

  5. 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.

  6. 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.

  7. A method for 3D reconstruction of coronary arteries using biplane angiography and intravascular ultrasound images

    Microsoft Academic Search

    Christos V. Bourantas; Iraklis C. Kourtis; Marina E. Plissiti; Dimitrios I. Fotiadis; Christos S. Katsouras; Michail I. Papafaklisb; Lampros K. Michalis

    2005-01-01

    The aim of this study is to describe a new method for the three-dimensional reconstruction of coronary arteries and its quantitative validation. Our approach is based on the fusion of the data provided by intravascular ultrasound images (IVUS) and biplane angiographies. A specific segmentation algorithm is used for the detection of the regions of interest in intravascular ultrasound images. A

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

    PubMed

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

    2015-02-21

    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. PMID:25632958

  9. 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.

  10. 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.

  11. Impact of coronary artery bypass grafting on various aspects of quality of life

    Microsoft Academic Search

    Helén Sjöland; Kenneth Caidahl; Ingela Wiklund; Maria Haglid; Marianne Hartford; Björn W Karlson; Thomas Karlsson; Johan Herlitz

    1997-01-01

    Objective: To prospectively study the improvement in quality of life (QoL) after coronary artery bypass surgery (CABG). Patients and Methods: Consecutive patients (n=2121) who underwent CABG at Sahlgrenska University Hospital between 1988 and 1991 received 3 questionnaires for the study of QoL: the Physical Activity Score, the Nottingham Health Profile and the Psychological General Well-being Index, which were responded both

  12. Impact of coronary artery bypass grafting on various aspects of quality of life

    Microsoft Academic Search

    Helen Sjoland; Kenneth Caidahl; Ingela Wiklund; Maria Haglid; Marianne Hartford; Bjorn W. Karlson; Thomas Karlsson; Johan Herlitz; Astra Hassle AB

    Objective: To prospectively study the improvement in quality of life (QoL) after coronary artery bypass surgery (CABG). Patients and Methods: Consecutive patients (n2121) who underwent CABG at Sahlgrenska University Hospital between 1988 and 1991 received 3 questionnaires for the study of QoL: the Physical Activity Score, the Nottingham Health Profile and the Psychological General Well-being Index, which were responded both

  13. 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

  14. 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.

  15. Automatic segmentation of arteries in multi-stain histology images L. Leal Taixe1, A. U. Coskun2, B. Rosenhahn1 and D. H. Brooks2

    E-print Network

    Automatic segmentation of arteries in multi-stain histology images L. Leal Taix´e1, A. U. Coskun2 or Coronary Artery Disease (CAD) is a serious disease caused by the formation of plaque in the arteries detector is intro- duced to capture the area of the artery within the image. 2. We propose to create

  16. Content quality based image retrieval with multiple instance boost ranking

    Microsoft Academic Search

    Peng Yang; Hui Li; Qingshan Liu; Lin Zhong; Dimitris Metaxas

    2011-01-01

    Most previous works treated image retrieval as a classification problem or a similarity measurement problem. In this paper, we propose a new idea for image retrieval, in which we regard image retrieval as a ranking issue by evaluating image content quality. Based on the content preference between the images, the image pairs are organized to build the data set for

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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 ?m, for example, a low signal in each pixel limits lateral resolution because of 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.

  18. Reconstruction algorithm for improved ultrasound image quality.

    PubMed

    Madore, Bruno; Meral, F Can

    2012-02-01

    A new algorithm is proposed for reconstructing raw RF data into ultrasound images. Previous delay-and-sum beamforming reconstruction algorithms are essentially one-dimensional, because a sum is performed across all receiving elements. In contrast, the present approach is two-dimensional, potentially allowing any time point from any receiving element to contribute to any pixel location. Computer-intensive matrix inversions are performed once, in advance, to create a reconstruction matrix that can be reused indefinitely for a given probe and imaging geometry. Individual images are generated through a single matrix multiplication with the raw RF data, without any need for separate envelope detection or gridding steps. Raw RF data sets were acquired using a commercially available digital ultrasound engine for three imaging geometries: a 64-element array with a rectangular field-of- view (FOV), the same probe with a sector-shaped FOV, and a 128-element array with rectangular FOV. The acquired data were reconstructed using our proposed method and a delay- and-sum beamforming algorithm for comparison purposes. Point spread function (PSF) measurements from metal wires in a water bath showed that the proposed method was able to reduce the size of the PSF and its spatial integral by about 20 to 38%. Images from a commercially available quality-assurance phantom had greater spatial resolution and contrast when reconstructed with the proposed approach. PMID:24626030

  19. Reconstruction algorithm for improved ultrasound image quality

    PubMed Central

    Madore, Bruno; Meral, F. Can

    2012-01-01

    A new algorithm is proposed for reconstructing raw RF data into ultrasound images. Prior delay-and-sum beamforming reconstruction algorithms are essentially one-dimensional, as a sum is performed across all receiving elements. In contrast, the present approach is two-dimensional, potentially allowing any time point from any receiving element to contribute to any pixel location. Computer-intensive matrix inversions are performed once-and-for-all ahead of time, to create a reconstruction matrix that can be reused indefinitely for a given probe and imaging geometry. Individual images are generated through a single matrix multiplication with the raw RF data, without any need for separate envelope detection or gridding steps. Raw RF datasets were acquired using a commercially available digital ultrasound engine for three imaging geometries: a 64-element array with a rectangular field-of-view (FOV), the same probe with a sector-shaped FOV, and a 128-element array with rectangular FOV. The acquired data were reconstructed using our proposed method and a delay-and-sum beamforming algorithm, for comparison purposes. Point-spread-function (PSF) measurements from metal wires in a water bath showed the proposed method able to reduce the size of the PSF and/or its spatial integral by about 20 to 38%. Images from a commercially available quality-assurance phantom featured greater spatial resolution and/or contrast when reconstructed with the proposed approach. PMID:24626030

  20. Peripheral Arterial Disease

    MedlinePLUS

    ... the legs. Normal Artery and Artery With Plaque Buildup The illustration shows how P.A.D. can ... artery. Figure B shows an artery with plaque buildup that's partially blocking blood flow. The inset image ...

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

    SciTech Connect

    Chun, Joo-Young, E-mail: drjyc78@gmail.com; Morgan, Robert; Belli, Anna-Maria [St. George's Hospital, Department of Radiology (United Kingdom)

    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.

  2. 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

  3. Image-based modeling of the hemodynamics in cerebral arterial trees

    NASA Astrophysics Data System (ADS)

    Mut, Fernando; Wright, Susan; Putman, Christopher; Ascoli, Giorgio; Cebral, Juan

    2009-02-01

    Knowledge of the hemodynamics in normal arterial trees of the brain is important to better understand the mechanisms responsible for the initiation and progression of cerebrovascular diseases. Information about the baseline values of hemodynamic variables such as velocity magnitudes, swirling flows, wall shear stress, pressure drops, vascular resistances, etc. is important for characterization of the normal hemodynamics and comparison with pathological states such as aneurysms and stenoses. This paper presents image-based computational hemodynamics models of cerebral arterial trees constructed from magnetic resonance angiography (MRA) images. The construction of large models of cerebral arterial trees is challenging because of the following main reasons: a) it is necessary to acquire high resolution angiographic images covering the entire brain, b) it is necessary to construct topologically correct and geometrically accurate watertight models of the vasculature, and c) the models typically result in large computational grids which make the calculations computationally demanding. This paper presents a methodology to model the hemodynamics in the brain arterial network that combines high resolution MRA at 3T, a vector representation of the vascular structures based on semi-manual segmentation, and a novel algorithm to solve the incompressible flow equations efficiently in tubular geometries. These techniques make the study of the hemodynamics in the cerebral arterial network practical.

  4. 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.

  5. Visualisation of the left anterior descending coronary artery on CT images used for breast radiotherapy planning

    PubMed Central

    Vennarini, S; Aristei, C; de Almeida, C E; Servois, V; Campana, F; Mosseri, V; Fourquet, A; Kirova, Y M

    2013-01-01

    Objective: To assess the visualisation of the left anterior descending (LAD) coronary artery on CT images used for breast radiation treatment planning. Methods: Delineation of the LAD artery was achieved for 25 breast patients by 1 radiologist and 1 radiation oncologist independently on two sets of images for each patient: one pre-operative CT scan using intravenous (IV) contrast media to determine the primary gross tumour volume (GTV) and one post-operative CT scan used for treatment planning. A Student’s paired t-test was used to compare the number of CT slices in which the LAD was visible for each patient in the two series. Interpolations and extrapolations of the LAD volume were performed for the left-sided cases using a published heart atlas in order to report doses to the LAD structure. Results: There was a non-significant difference between the results with and without IV contrast media (p=0.34 for the radiologist; p=0.90 for the radiation oncologist). The visible LAD artery corresponded to a 30% portion (range 12–47%) of the interpolated structure. The maximum dose to the left artery varied widely, from 2.7 to 41.7?Gy, in the group of patients with left breast tumours. The largest values (>25?Gy) corresponded to those patients in whom the LAD artery distal extremity lay inside the breast fields. Conclusions: With the current planning CT protocol, only one-third of the LAD artery could be objectively visualised. Contrast-enhanced imaging used for GTV delineation before the breast surgery did not improve the visualisation of the artery. Advances in Knowledge: This study has revealed the lack of consistency that may be encountered when contouring heart vessels, thereby questioning the reliability of dose reporting. PMID:23440165

  6. 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.

  7. Brain and arterial abnormalities following prenatal X-ray irradiation in mice assessed by magnetic resonance imaging and angiography.

    PubMed

    Saito, Shigeyoshi; Sawada, Kazuhiko; Mori, Yuki; Yoshioka, Yoshichika; Murase, Kenya

    2015-05-01

    The present study aimed to quantitatively characterize changes in the whole brain and arterial morphology in response to prenatal ionizing irradiation. Magnetic resonance imaging (MRI) and angiography (MRA) were used to evaluate brain and arterial abnormalities in 8-week-old male mice prenatally exposed to X-ray radiation at a dose of 0.5 or 1.0 Gy on embryonic day (E) 13. Irradiated mice demonstrated decreased brain volume, increased ventricular volume, and arterial malformation. Additionally, MRA signal intensity and arterial thickness in the anterior cerebral artery, middle cerebral artery, and basilar artery were lower in radiation-exposed mice than in control mice. MRI and MRA are useful tools for assessing brain and arterial abnormalities after prenatal exposure to radiation. PMID:25534523

  8. 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.

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

    E-print Network

    Kodge, B G

    2011-01-01

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

  10. Noninvasive determination of local wavespeed and distensibility of the femoral artery by comb-excited Fourier velocity-encoded magnetic resonance imaging: Measurements on athletic and nonathletic human subjects

    Microsoft Academic Search

    Maria Tarnawski; Gerard Cybulski; Denis Doorly; Charles Dumoulin; Robert Darrow; Colin Caro

    1994-01-01

    Summary The local distensibility of arteries is of interest because distensibility varies from artery to artery, may be altered by disease to different extents in different arteries, and may be modified by physiological or pharmacological means. Using magnetic resonance imaging (MRI) we have measured local arterial wavespeed in the femoral artery in healthy human subjects and calculated local arterial distensibility.

  11. Environmental impact of cardiac imaging tests for the diagnosis of coronary artery disease

    Microsoft Academic Search

    Thomas H Marwick; Jonathan Buonocore

    2011-01-01

    The use of cardiovascular imaging is growing inexorably and concerns have been expressed about its cost and radiation safety. In this study, the relative environmental impact of MRI, single photon emission tomography and cardiac ultrasound (echo) for the diagnosis of coronary artery disease were examined. The results emphasise that echo causes the least environmental impact at each stage of its

  12. Evaluation of Severe Subclavian Artery Stenosis by Color Doppler Flow Imaging

    Microsoft Academic Search

    Yang Hua; Lingyun Jia; Liang Li; Chen Ling; Zhongrong Miao; Liqun Jiao

    2011-01-01

    This study evaluates the diagnostic value of the hemodynamic parameters of color Doppler flow imaging (CDFI) for severe (70 to 99%) subclavian artery stenosis (SAS) using digital subtraction angiography (DSA) as the reference standard. Two-hundred fifty-two patients with suspected SAS were recruited into the study and examined from June 2005 to December 2009. The degree of stenosis was classified as

  13. WAVELET-BASED FOVEATED IMAGE QUALITY MEASUREMENT FOR REGION OF INTEREST IMAGE CODING

    Microsoft Academic Search

    Zhou Wang; Alan C. Bovik; Ligang Lu

    2002-01-01

    Region of interest (ROI) image and video compression techniques have been widely used in visual communication applications in an effort to deliver good quality images and videos at limited bandwidths. Most image quality metrics have been developed for uniform resolution images. These metrics are not appropriate for the assessment of ROI coded images, where space-variant resolution is necessary. The spatial

  14. Vascular Fluorescence Imaging Control for Complex Renal Artery Aneurysm Repair Using Laparoscopic Nephrectomy and Autotransplantation

    PubMed Central

    Tozzi, Matteo; Boni, Luigi; Soldini, Gabriele

    2014-01-01

    Intraoperative fluorescent imaging using indocyanine green enables vascular surgeons to confirm the location and states of the reconstructed vessels during surgery. Complex renal artery aneurysm repair involving second order branch vessels has been performed with different techniques. We present a case of ex vivo repair and autotransplantation combining the advantages of minimally invasive surgery and indocyanine green enhanced fluorescence imaging to facilitate vascular anatomy recognition and visualization of organ reperfusion. PMID:25177511

  15. 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

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

    PubMed Central

    Louw, Louise; Steyl, Johan; Loggenberg, Eugene

    2014-01-01

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

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

    PubMed

    Louw, Louise; Steyl, Johan; Loggenberg, Eugene

    2014-01-01

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

  18. World Health Organization quality of life instrument-brief and Short Form36 in patients with coronary artery disease: Do they measure similar quality of life concepts?

    Microsoft Academic Search

    Luciane Nascimento Cruz; Suzi Alves Camey; Marcelo Pio Fleck; Carisi Anne Polanczyk

    2009-01-01

    This study aimed to assess the validity and reliability of World Health Organization Quality of Life Instrument (WHOQOL)-brief and SF-36 in patients with coronary artery disease (CAD). Considering that depression is known to be associated with bad outcomes in CAD and it is highly associated with poor Quality of Life (QOL), we tested the correlation between WHOQOL and SF-36 and

  19. Advanced Image Quality Studies of LCTVs Justin Laird

    E-print Network

    Zanibbi, Richard

    Advanced Image Quality Studies of LCTVs Justin Laird B.S. Imaging and Photographic Technology of Technology Rochester, New York Certificate of Approval M.S. Degree Thesis The M.S. Degree Thesis of Justin, New York Title of Thesis: Advanced Image Quality Studies of LCTVs I, Justin L. Laird, hereby grant

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

    E-print Network

    Zanibbi, Richard

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

  1. Image quality assessment: from error visibility to structural similarity

    Microsoft Academic Search

    Zhou Wang; Alan Conrad Bovik; Hamid Rahim Sheikh; Eero P. Simoncelli

    2004-01-01

    Objective methods for assessing perceptual image quality traditionally attempted to quantify the visibility of errors (differences) between a distorted image and a reference image using a variety of known properties of the human visual system. Under the assumption that human visual perception is highly adapted for extracting structural information from a scene, we introduce an alternative complementary framework for quality

  2. An ICA-based approach for image quality assessment

    NASA Astrophysics Data System (ADS)

    Shi, Yunyu; Ding, Youdong; Li, Jun

    2009-10-01

    In this paper, we propose an ICA-based approach for assessing image quality. Independent component analysis (ICA), which is a kind of fundamental statistical model for natural images, could model images as linear superpositions of basis images. The features given by ICA are suitable for image quality assessment because they resemble the representation given by simple-cells in the mammalian primary visual cortex. The steps of the proposed approach are listed concisely as follows: estimation of basis images in the ICA model; image features extraction from reference images and their corresponding distorted images; calculation of image quality scores or scales. Our experimental results show that the proposed method could achieve competitive performance with other two typical models, Structure SIMilarity (SSIM) and Visual Information Fidelity (VIF) by being tested on LIVE Subjective database. Some factors that may influence the performance results, such as the size of sliding window, the total number of image patches, are also discussed.

  3. Image quality assessment using singular vectors

    NASA Astrophysics Data System (ADS)

    Yang, Chin-Ann; Kaveh, Mostafa

    2010-01-01

    A new Full-Reference Singular Value Decomposition (SVD) based Image Quality Measurement (IQM) is proposed in this paper. Most of the recently developed IQMs that have been designed for measuring universal distortion types have worse results in measuring blur type distortions. The proposed method A-SVD aims at capturing the loss of structural content instead of measuring the distortion of pixel intensity value. A-SVD uses the change in the angle between the principal singular vectors as a distance between the original and distorted image blocks. Experiments were conducted using the LIVE database. The proposed algorithm was compared with another recently proposed SVD based method named M-SVD and other well-established methods including SSIM, MSSIM, and VSNR. Results have shown that the proposed method has an advantage in discerning blurry types of image distortions while providing comparable results for other distortion types. Also, the proposed method provides better linear correlation with the human score, which is a desirable attribute for the IQM to be used in other applications.

  4. 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

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

    NASA Astrophysics Data System (ADS)

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

    2010-01-01

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

  6. Syntactic reasoning and pattern recognition for analysis of coronary artery images.

    PubMed

    Ogiela, Marek R; Tadeusiewicz, Ryszard

    2002-01-01

    This paper presents a new approach to the application of structural pattern recognition methods for image understanding, based on content analysis and knowledge discovery performed on medical images. This presents in particular computer analysis and recognition of local stenoses of the coronary arteries lumen. These stenoses are the result of the appearance of arteriosclerosis plaques, which in consequence lead to different forms of ischemic cardiovascular diseases. Such diseases may be seen in the form of stable or unstable disturbances of heart rhythm or infarctions. Analysis of the correct morphology of these arteries lumen is possible with the application of the syntactic analysis and pattern recognition methods, in particular with the attributed grammar of LALR type. In the paper, we shall describe all stages of analysis and understanding of images in the context of obtained features, and we shall also present the proper algorithm of syntactic reasoning based on the acquired knowledge. PMID:12234721

  7. 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

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

    SciTech Connect

    Rohkohl, Christopher; Bruder, Herbert; Stierstorfer, Karl [Siemens AG, Healthcare Sector, Siemensstrasse 1, 91301 Forchheim (Germany); Flohr, Thomas [Siemens AG, Healthcare Sector, Siemensstrasse 1, 91301 Forchheim (Germany); Institute of Diagnostic Radiology, Eberhard Karls University, Hoppe-Seyler-Str. 3, 72076 Tuebingen (Germany)

    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.

  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. 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

  11. Anatomy-based image processing analysis of the running pattern of the perioral artery for minimally invasive surgery.

    PubMed

    Lee, Sang-Hee; Lee, Minho; Kim, Hee-Jin

    2014-10-01

    We aimed to elucidate the tortuous course of the perioral artery with the aid of image processing, and to suggest accurate reference points for minimally invasive surgery. We used 59 hemifaces from 19 Korean and 20 Thai cadavers. A perioral line was defined to connect the point at which the facial artery emerged on the mandibular margin, and the ramification point of the lateral nasal artery and the inferior alar branch. The course of the perioral artery was reproduced as a graph based on the perioral line and analysed by adding the image of the artery using MATLAB. The course of the artery could be classified into 2 according to the course of the alar branch - oblique and vertical. Two distinct inflection points appeared in the course of the artery along the perioral line at the ramification points of the alar branch and the inferior labial artery, respectively, and the course of the artery across the face can be predicted based on the following references: the perioral line, the ramification point of the alar branch (5?10 mm medial to the perioral line at the level of the lower third of the upper lip) and the inferior labial artery (5?10 mm medial to the perioral line at the level of the middle of the lower lip). PMID:25081954

  12. 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.

  13. Image Quality Assessment Kalpana Seshadrinathan, Thrasyvoulos N. Pappas,

    E-print Network

    Wang, Zhou

    Image Quality Assessment Kalpana Seshadrinathan, Thrasyvoulos N. Pappas, Robert J. Safranek of Image Processing, Elsevier, 2009. #12;1 Introduction Recent advances in digital imaging technology, computational speed, storage capacity, and networking have resulted in the proliferation of digital images, both

  14. Evidence for myocardial CT perfusion imaging in the diagnosis of hemodynamically significant coronary artery disease

    PubMed Central

    2015-01-01

    This editorial discusses a recent paper published in the August issue of Radiology about the diagnostic value of myocardial computer tomography (CT) perfusion imaging in the detection of hemodynamically significant coronary stenosis when compared to single-photon emission CT (SPECT) imaging based on a secondary analysis of CORE320 study. Three aspects including high diagnostic sensitivity of CT perfusion imaging, moderate specificity of SPECT imaging and lack of use of attenuation correction in SPECT imaging have been discussed with reference to the current literature, and some suggestions have been highlighted for future studies to improve the diagnostic performance of CT perfusion and SPECT imaging in the diagnostic evaluation of coronary artery disease. PMID:25774349

  15. 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 [Fraunhofer MEVIS, Institute for Medical Image Computing, Universitaetsallee 29, 28359 Bremen (Germany)] [Fraunhofer MEVIS, Institute for Medical Image Computing, Universitaetsallee 29, 28359 Bremen (Germany); Welter, Stefan [Ruhrlandklinik, Department of Thoracic Surgery, Tueschener Weg 40, 45239 Essen (Germany)] [Ruhrlandklinik, Department of Thoracic Surgery, Tueschener Weg 40, 45239 Essen (Germany); Peitgen, Heinz-Otto [Jacobs University Bremen, Campus Ring 1, 28759 Bremen (Germany)] [Jacobs University Bremen, Campus Ring 1, 28759 Bremen (Germany)

    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.

  16. 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

  17. Determination of the quantitative thallium imaging variables that optimize detection of coronary artery disease

    SciTech Connect

    Kaul, S.; Boucher, C.A.; Newell, J.B.; Chesler, D.A.; Greenberg, J.M.; Okada, R.D.; Strauss, H.W.; Dinsmore, R.E.; Pohost, G.M.

    1986-03-01

    Although quantification of exercise thallium images has been previously reported, the relative value of different imaging variables for detection of coronary artery disease has not been analyzed in a large group of patients with cardiac catheterization data. Regional initial thallium uptake, redistribution and clearance on thallium study were measured in 325 patients also undergoing cardiac catheterization (281 patients with and 44 patients without coronary artery disease). Normal values were defined in 55 other clinically normal subjects. When five myocardial segments were analyzed in each view, the respective values for sensitivity and specificity were 95 and 50% for initial thallium uptake, 60 and 87% for redistribution and 74 and 66% for clearance. Initial thallium uptake was the most sensitive but least specific (p less than 0.001), whereas redistribution was the least sensitive and most specific (p less than 0.001). Using stepwise logistic regression analysis, the best correlate of coronary artery disease was initial thallium uptake. Addition of redistribution to a mathematical model of the probability of coronary artery disease did not alter sensitivity, but increased specificity from 50 to 70% (p less than 0.001). Once initial uptake and redistribution were considered, myocardial thallium clearance provided no additional improvement in the correlation. Excluding the two basal segments in each view from the analysis increased the specificity from 70 to 80% (p less than 0.001) without affecting sensitivity. Of the 15 patients (5%) with coronary disease not detected using this approach, none had left main disease and 10 (67%) had one vessel disease. A combination of variables derived from quantification of exercise thallium images provides a superior sensitivity and specificity for the detection of coronary artery disease compared with the use of a single variable.

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

    PubMed

    Cicchi, Riccardo; Baria, Enrico; Matthäus, Christian; Lange, Marta; Lattermann, Annika; Brehm, Bernhard R; Popp, Jürgen; Pavone, Francesco Saverio

    2015-04-01

    Atherosclerosis is one of the leading causes of death in the Western World and its characterization is extremely interesting from the diagnostic point of view. Here, we employed combined SHG-FLIM microscopy to characterize arterial tissue with atherosclerosis. The shorter mean fluorescence lifetime measured within plaque depositions (1260 ± 80 ps) with respect to normal arterial wall (1480 ± 100 ps) allowed discriminating collagen from lipids. SHG measurements and image analysis demonstrated that the normal arterial wall has a more anisotropic Aspect Ratio (0.37 ± 0.02) with respect to plaque depositions (0.61 ± 0.02) and that the correlation length can be used for discriminating collagen fibre bundles (2.0 ± 0.6 µm) from cholesterol depositions (4.1 ± 0.6 µm). The presented method has the potential to find place in a clinical setting as well as to be applied in vivo in the near future. Graphic composition of SHG and FLIM images representing normal arterial wall and plaque depositions. PMID:25760563

  19. 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.

  20. System design and image processing algorithms for frequency domain optical coherence tomography in the coronary arteries

    NASA Astrophysics Data System (ADS)

    Adler, Desmond C.; Xu, Chenyang; Petersen, Christopher; Schmitt, Joseph M.

    2010-02-01

    We report on the design of a frequency domain optical coherence tomography (FD-OCT) system, fiber optic imaging catheter, and image processing algorithms for in vivo clinical use in the human coronary arteries. This technology represents the third generation of commercially-available OCT system developed at LightLab Imaging Inc. over the last ten years, enabling three-dimensional (3D) intravascular imaging at unprecedented speeds and resolutions for a commercial system. The FD-OCT engine is designed around an exclusively licensed micro-cavity swept laser that was co-developed with AXSUN Technologies Ltd. The laser's unique combination of high sweep rates, broad tuning ranges, and narrow linewidth enable imaging at 50,000 axial lines/s with an axial resolution of < 16 ?m in tissue. The disposable 2.7 French (0.9 mm) imaging catheter provides a spot size of < 30 ?m at a working distance of 2 mm. The catheter is rotated at 100 Hz and pulled back 50 mm at 20 mm/s to conduct a high-density spiral scan in 2.5 s. Image processing algorithms have been developed to provide clinically important measurements of vessel lumen dimensions, stent malapposition, and neointimal thickness. This system has been used in over 2000 procedures since August 2007 at over 40 clinical sites, providing cardiologists with an advanced tool for 3D assessment of the coronary arteries.

  1. Contrast sensitivity function calibration based on image quality prediction

    NASA Astrophysics Data System (ADS)

    Han, Yu; Cai, Yunze

    2014-11-01

    Contrast sensitivity functions (CSFs) describe visual stimuli based on their spatial frequency. However, CSF calibration is limited by the size of the sample collection and this remains an open issue. In this study, we propose an approach for calibrating CSFs that is based on the hypothesis that a precise CSF model can accurately predict image quality. Thus, CSF calibration is regarded as the inverse problem of image quality prediction according to our hypothesis. A CSF could be calibrated by optimizing the performance of a CSF-based image quality metric using a database containing images with known quality. Compared with the traditional method, this would reduce the work involved in sample collection dramatically. In the present study, we employed three image databases to optimize some existing CSF models. The experimental results showed that the performance of a three-parameter CSF model was better than that of other models. The results of this study may be helpful in CSF and image quality research.

  2. Reduced-Reference Quality Assessment for JPEG-2000 Compressed Image

    NASA Astrophysics Data System (ADS)

    Park, Ha-Joong; Jung, Ho-Youl

    Image quality assessment method is a methodology that measures the difference of quality between the reference image and its distorted one. In this paper, we propose a novel reduced-reference (RR) quality assessment method for JPEG-2000 compressed images, which exploits the statistical characteristics of context information extracted through partial entropy decoding or decoding. These statistical features obtained in the process of JPEG-2000 encoding are transmitted to the receiver as side information and used to estimate the quality of images transmitted over various noisy channels at the decompression side. In the framework of JPEG-2000, the context of a current coefficient is determined depending on the pattern of the significance and/or the sign of its neighbors in three bit-plane coding passes and four coding modes. As the context information represents the local property of images, it can efficiently describe textured pattern and edge orientation. The quality of transmitted images is measured by the difference of entropy of context information between received and original images. Moreover, the proposed quality assessment method can directly process the images in the JPEG-2000 compressed domain without full decompression. Therefore, our proposed can accelerate the work of assessing image quality. Through simulations, we demonstrate that our method achieves fairly good performance in terms of the quality measurement accuracy as well as the computational complexity.

  3. 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.

  4. 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.

  5. Quality assessment of images illuminated by dim LCD backlight

    NASA Astrophysics Data System (ADS)

    Huang, Tai-Hsiang; Kao, Chen-Tai; Chen, Homer H.

    2012-03-01

    We consider the quality assessment of images displayed on a liquid crystal display (LCD) with dim backlight-a situation where the power consumption of the LCD is set to a low level. This energy saving mode of LCD decreases the perceived image quality. In particular, some image regions may appear so dark that they become non-perceptible to human eye. The problem becomes more severe when the image is illuminated with very dim backlight. Ignoring the effect of dim backlight on image quality assessment and directly applying an image quality assessment metric to the entire image may produce results inconsistent with human evaluation. We propose a method to fix the problem. The proposed method works as a precursor of image quality assessment. Specifically, given an image and the backlight intensity level of the LCD on which the image is to be displayed, the method automatically classifies the pixels of an image into perceptible and non-perceptible pixels according to the backlight intensity level and excludes the nonperceptible pixels from quality assessment. Experimental results are shown to demonstrate the performance of the proposed method.

  6. 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

  7. Arterial Spin Label Imaging of Acute Ischemic Stroke and Transient Ischemic Attack

    PubMed Central

    Zaharchuk, Greg

    2011-01-01

    Since acute ischemic stroke and transient ischemic attack (TIA) are fundamentally disruptions of brain hemodynamics, neuroimaging of brain perfusion might be expected to be of clinical utility. Recently, a noncontrast method of measuring CBF using arterial spin labeling (ASL) has become feasible in the clinical setting. It has advantages when compared to dynamic susceptibility contrast (DSC) bolus contrast perfusion-weighted imaging (PWI) that include lack of exposure to gadolinium-based contrast materials, improved quantitation, and decreased sensitivity to susceptibility artifacts and motion. Drawbacks of ASL include reduced signal-to-noise (SNR) and high sensitivity to arterial transit delays. While deleterious for quantitative perfusion measurements, the sensitivity of ASL to late arriving blood can be beneficial to visualize collateral flow. This chapter will discuss ASL imaging findings in patients presenting with acute ischemic stroke and TIA, focusing on typical appearances, common artifacts, and comparisons with bolus contrast PWI. PMID:21640300

  8. 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. [Academic Medical Centre Amsterdam, Department of Gynaecology (Netherlands)], E-mail: w.j.k.hehenkamp@amc.uva.nl; Volkers, Nicole A. [Academic Medical Centre Amsterdam, Department of Radiology (Netherlands); Bartholomeus, Wouter [Academic Medical Centre Amsterdam, Faculty of Medicine (Netherlands); Blok, Sjoerd de [Onze Lieve Vrouwe Gasthuis, Amsterdam, Department of Gynaecology (Netherlands); Birnie, Erwin [Academic Medical Centre Amsterdam, Public Health Epidemiology (Netherlands); Reekers, Jim A. [Academic Medical Centre Amsterdam, Department of Radiology (Netherlands); Ankum, Willem M. [Academic Medical Centre Amsterdam, Department of Gynaecology (Netherlands)

    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.

  9. An efficient two-stage approach for image-based FSI analysis of atherosclerotic arteries

    Microsoft Academic Search

    Joseph R. Leach; Vitaliy L. Rayz; Mohammad R. K. Mofrad; David Saloner

    2010-01-01

    Patient-specific biomechanical modeling of atherosclerotic arteries has the potential to aid clinicians in characterizing\\u000a lesions and determining optimal treatment plans. To attain high levels of accuracy, recent models use medical imaging data\\u000a to determine plaque component boundaries in three dimensions, and fluid–structure interaction is used to capture mechanical\\u000a loading of the diseased vessel. As the plaque components and vessel wall

  10. Relationship Between Carotid Artery Calcification Detected in Dental Panoramic Images and Hypertension and Myocardial Infarction

    PubMed Central

    Moshfeghi, Mahkameh; Taheri, Jamileh Beigom; Bahemmat, Nika; Evazzadeh, Mohammad Ebrahim; Hadian, Hoora

    2014-01-01

    Background: Carotid artery calcification may be related to cerebrovascular accident, which may result in death or physical and mental disabilities in survivors. Objectives: Our purpose is to study the association of carotid artery calcification (CAC) on dental panoramic radiographs and two risk factors of cerebrovascular accident (CVA) including hypertension and myocardial infarction (MI). Patients and Methods: Panoramic images of 200 patients that were all women above 50 years of age (a population suffering from vascular diseases) were investigated. All panoramic images were provided under similar conditions in terms of the type of panoramic radiograph equipment, type of applied films and the automatic film processor. Then, the patients answered questions about MI history and taking antihypertensive drugs. We also measured the blood pressure of patients in two separate surveys. Data analysis was performed by SPSS statistical program. We used Exact Fisher test and Chi-Square test at a significant level of less than 0.05 to study the effect of these variables on the occurrence of carotid artery calcification. Results: Among 200 studied samples, 22 of the patients (11%) had carotid artery calcification on the dental panoramic radiograph. In total, 52 patients (26%) had hypertension and four people (2%) had a history of MI. Eleven individuals among patients suffering from hypertension (21.2%) and three individuals among patients with a history of MI (75%) demonstrated CAC on dental panoramic images . Conclusions: The relationship between CAC found on dental panoramic radiographs and two CVA risk factors--hypertension and MI-- was significant. Therefore, it seems that detection of CAC on panoramic images of dental patients must be considered by dentists.

  11. Highly Diffusion-Sensitized Tensor Imaging of Unilateral Cerebral Arterial Occlusive Disease

    Microsoft Academic Search

    Atsushi Shiraishi; Yasuhiro Hasegawa; Shunichi Okada; Kazumi Kimura; Tohru Sawada; Hidehiro Mizusawa; Kazuo Minematsu

    2005-01-01

    BACKGROUND AND PURPOSE: Selective neuronal death is a well-recognized histopatho- logic sequel to moderate ischemic brain damage. However, radiologic visualization of these changes has not been established, even with diffusion tensor imaging (DTI). We sought to determine whether DTI with b values >1900 s\\/mm2 reveals occult diffusion abnormalities in patients with cerebral arterial occlusive disease. METHODS: Six patients (five men,

  12. 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.

  13. 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.

  14. Meat Quality Evaluation by Hyperspectral Imaging Technique: An Overview

    Microsoft Academic Search

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

    2012-01-01

    During the last two decades, a number of methods have been developed to objectively measure meat quality attributes. Hyperspectral imaging technique as one of these methods has been regarded as a smart and promising analytical tool for analyses conducted in research and industries. Recently there has been a renewed interest in using hyperspectral imaging in quality evaluation of different food

  15. Telepresence and Video Games: The Impact of Image Quality

    Microsoft Academic Search

    Cheryl Campanella Bracken; Paul Skalski

    2009-01-01

    This study investigates the impact of video game image quality on telepresence. Past research has demonstrated positive associations between television image quality and presence and video game technology and presence. No study to date, however, has examined the presence effects of video games played in high definition, which is becoming increasingly common due to the diffusion of new TV technologies

  16. Determination of culprit coronary artery branches using hemodynamic indices from angiographic images.

    PubMed

    Zhang, Zhang; Chen, Jun; Takarada, Shigeho; Molloi, Sabee

    2015-01-01

    A recently reported angiographic technique for hemodynamic indices based on first-pass distribution analysis (FPA) could potentially be helpful for determining the culprit artery responsible for myocardial ischemia. The purpose of this study was to determinate the culprit coronary arterial branches based on coronary flow reserve (CFR) and fractional flow reserve (FFR) using only angiographic images. The study was performed in 14 anesthetized swine. Microspheres were injected into coronary arterial branches to create microvascular disruption. Stenosis was also created by inserting plastic tubings in LAD and LCX arterial branches. Adenosine was used to produce maximum hyperemia. Angiographic CFR (CFRa), relative angiographic CFR (rCFRa), and angiographic FFR (FFRa) were calculated by FPA. The diagnostic abilities of CFRa, rCFRa, and FFRa were compared in three models: (1) epicardial stenosis model (S), (2) microcirculation disruption model (M), and (3) combined(S + M) model by using the area under the ROC curve (AUC). The mean differences between FFRa and the pressure-derived FFR (FFRp) measurements were -0.01 ± 0.21 in S model (N = 37) and 0.01 ± 0.18 in M model (N = 53). From 225 measurements in S model, the AUCs for CFRa and FFRa were 0.720 and 0.918, respectively. From 262 measurements in M model and 238 measurements in (S + M) model, the AUCs for CFRa, rCFRa, FFRa were 0.744, 0.715, 0.959 and 0.806, 0.738, 0.995, respectively. The hemodynamic indices of the small branches (down to ~0.7 mm) could be measured using only angiographic image data. The application of FFRa could potentially provide a useful method to assess the severity of disease in coronary arterial branches. PMID:25288357

  17. Generalized relative quality assessment scheme for reconstructed medical images.

    PubMed

    Wang, Shaoze; Ding, Yong; Dai, Hang; Qian, Dahong; Yu, Xinfeng; Zhang, Minming

    2014-01-01

    A generalized relative quality (RQ) assessment scheme is proposed here based on the Bayesian inference theory, which is reasonable to make use of full reference (FR) algorithms when the evaluation of the quality of homogeneous medical images is required. Each FR algorithm is taken as a kernel to represent the level of quality. Although, various kernels generate different order of magnitude, a normalization process can rationalize the quality index within 0 and 1, where 1 represent the highest quality and 0 represents the lowest quality. To validate the performance of the proposed scheme, a series of reconstructed susceptibility weighted imaging images are collected, where each image has its subjective scale. Both experimental results and a ROC analysis show that the RQ obtained from the proposed scheme is consistent with subjective evaluation. PMID:25226992

  18. Image processing system performance prediction and product quality evaluation

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

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

    SciTech Connect

    Tavare, Aniket N. [British Medical Association House, British Medical Journal Group (United Kingdom); Alsafi, Ali, E-mail: ali.alsafi03@imperial.ac.uk; Hamady, Mohamad S. [St. Mary's Hospital, Imaging Department (United Kingdom)

    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.

  20. Retroesophageal brachiocephalic artery assessed by magnetic resonance imaging: a case report and literature review.

    PubMed

    Udupa, Sharmila; Smythe, John F; Wong, Derek T

    2014-12-01

    A right aortic arch with a retroesophageal brachiocephalic artery is a very rare type of vascular ring. We present a case report along with a review of published cases to date. Twelve publications from 1968-2014 describe a retroesophageal brachiocephalic artery in a total of 13 patients. The mean age at diagnosis was 8.7 ± 16 years. Four of the 13 patients were boys. Nearly half of the patients were symptomatic, with dysphagia or respiratory difficulties. Ten patients (77%) had associated congenital heart defects. Of the 13 patients with retroesophageal brachiocephalic artery, 12 had a right aortic arch, and only 1 had a left aortic arch associated with complex congenital heart disease. Investigations used in the diagnosis of the vascular ring include angiography, esophagography, echocardiography, and computed tomography. Only 2 patients had the diagnosis confirmed with magnetic resonance imaging (MRI), but this was in the setting of complex congenital heart disease. In conclusion, a right aortic arch with a retroesophageal left brachiocephalic artery is an extremely rare form of vascular ring and is often seen in association with other forms of congenital heart disease. Cardiac MRI can be used as a primary diagnostic modality for both the assessment of the vascular ring anatomy and the hemodynamics of associated cardiac malformations in the preoperative setting. PMID:25475473

  1. Prevalence of calcified carotid artery atheromas on panoramic images of individuals with primary hyperparathyroidism

    PubMed Central

    Friedlander, A H; Aghazadehsanai, N; Chang, T I; Harada, N; Garrett, N R

    2013-01-01

    Objectives: Primary hyperparathyroidism (PHPT), affecting 1% of the population, is associated with increased cardiovascular morbidity and mortality. The presence of calcified carotid artery plaque (CCAP) on panoramic images is a validated risk indicator of future adverse cardiovascular events. We hypothesized that military veterans aged 50 years or older diagnosed with PHPT by increased parathyroid hormone and calcium levels would frequently have CCAP on their images. Methods: We determined the prevalence rates of CCAP on the images of patients diagnosed with PHPT and evaluated their atherogenic risk profiles, including hypertension, dyslipidaemia, diabetes and obesity. Comparisons of atherogenic risk factors were made between subjects with and without observed CCAP on their panoramic images. Results: Of the 60 patients (86.7% males and 13.3% females, mean age 73.2 ± 11.3 years) with PHPT, 40% had atheromas. There were no significant differences between CCAP+ and CCAP? groups in gender or race (p > 0.05). The atherogenic profile (age, body mass index, hypertension, diabetes, hyperlipidaemia) in the CCAP+ and CCAP? groups was not significantly different (p > 0.05). Conclusions: Calcified carotid artery atheromas are often seen on the panoramic images of patients with PHPT. Thus, dentists must be uniquely vigilant for these lesions when evaluating these studies. PMID:23775925

  2. Adenosine stress thallium-201 myocardial perfusion imaging for detecting coronary artery disease at an early stage.

    PubMed

    Chen, Gui-Bing; Wu, Hua; He, Xiao-Jiang; Huang, Jin-Xiong; Yu, Dan; Xu, Wei-Yi; Yu, Hao

    2013-01-01

    The aims of this study were to evaluate the diagnostic value of adenosine thallium-201 myocardial perfusion imaging and to compare it with exercise stress thallium-201 myocardial perfusion imaging for detecting coronary artery disease (CAD) at an early stage. Forty-one patients suspected with CAD were randomly divided into two groups. In Group 1 (n=21) adenosine stress was undertaken; the exercise stress myocardial perfusion imaging was performed in Group 2 (n=20). Coronary angiography (CAG) was performed in each patient within 2 weeks before or after single photon emission computed tomography (SPECT). Adenosine stress group vs. exercise stress group, the sensitivity was 92.86% vs. 100.0%, specificity 57.14% vs. 60.0%, positive predictive value 81.25% vs. 71.43%, negative predictive value 80.0% vs. 100.0%, accuracy 80.95% vs. 80.0% respectively. Detection rates of vessels of coronary artery lesions were 66.67% in Group 1 and 72.22% in Group 2 (P> 0.05). The side effects were mild and transient. Our results demonstrated that adenosine stress myocardial perfusion imaging is a safe and reliable diagnostic method for an early stage of CAD. As a comparative sensitivity and accuracy with exercise stress thallium-201 myocardial perfusion imaging, adenosine stress testing may provide a feasible alternative pharmacological stress method in myocardial SPECT for detection of CAD. PMID:23694919

  3. 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. [National Co-ordinating Centre for the Physics of Mammography, Royal Surrey County Hospital NHS Foundation Trust, Guildford GU2 7XX, United Kingdom and Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH (United Kingdom); Jarvis Breast Screening and Diagnostic Centre, Guildford GU1 1LJ (United Kingdom); Department of Radiology, St. George's Healthcare NHS Trust, Tooting, London SW17 0QT (United Kingdom); Cambridge Breast Unit, Cambridge University Hospitals NHS Foundation Trust, Cambridge CB2 0QQ, United Kingdom and NIHR Cambridge Biomedical Research Centre, Cambridge CB2 0QQ (United Kingdom); Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania 15210 (United States); National Co-ordinating Centre for the Physics of Mammography, Royal Surrey County Hospital NHS Foundation Trust, Guildford GU2 7XX, United Kingdom and Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom); University Hospitals Leuven, Herestraat 49, 3000 Leuven (Belgium); National Co-ordinating Centre for the Physics of Mammography, Royal Surrey County Hospital NHS Foundation Trust, Guildford GU2 7XX, United Kingdom and Department of Physics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom)

    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.

  4. 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?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

  5. 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

  6. 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

  7. 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.

  8. Imaging-based treatment selection for intravenous and intra-arterial stroke therapies: a comprehensive review

    PubMed Central

    Yoo, Albert J; Pulli, Benjamin; Gonzalez, R Gilberto

    2011-01-01

    Reperfusion therapy is the only approved treatment for acute ischemic stroke. The current approach to patient selection is primarily based on the time from stroke symptom onset. However, this algorithm sharply restricts the eligible patient population, and neglects large variations in collateral circulation that ultimately determine the therapeutic time window in individual patients. Time alone is unlikely to remain the dominant parameter. Alternative approaches to patient selection involve advanced neuroimaging methods including MRI diffusion-weighted imaging, magnetic resonance and computed tomography perfusion imaging and noninvasive angiography that provide potentially valuable information regarding the state of the brain parenchyma and the neurovasculature. These techniques have now been used extensively, and there is emerging evidence on how specific imaging data may result in improved clinical outcomes. This article will review the major studies that have investigated the role of imaging in patient selection for both intravenous and intra-arterial therapies. PMID:21809968

  9. 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.

  10. Toward hemodynamic diagnosis of carotid artery stenosis based on ultrasound image data and computational modeling.

    PubMed

    Sousa, Luísa C; Castro, Catarina F; António, Carlos C; Santos, André Miguel F; dos Santos, Rosa Maria; Castro, Pedro Miguel A C; Azevedo, Elsa; Tavares, João Manuel R S

    2014-11-01

    The ability of using non-expensive ultrasound (US) image data together with computer fluid simulation to access various severities of carotid stenosis was inquired in this study. Subject-specific hemodynamic conditions were simulated using a developed finite element solver. Individual structured meshing of the common carotid artery (CCA) bifurcation was built from segmented longitudinal and cross-sectional US images; imposed boundary velocities were based on Doppler US measurements. Simulated hemodynamic parameters such as velocities, wall shear stress (WSS) and derived descriptors were able to predict disturbed flow conditions which play an important role in the development of local atherosclerotic plaques. Hemodynamic features from six individual CCA bifurcations were analyzed. High values of time-averaged WSS (TAWSS) were found at stenosis site. Low values of TAWSS were found at the bulb and at the carotid internal and external branches depending on the particular features of each patient. High oscillating shear index and relative residence time values assigned highly disturbed flows at the same artery surface regions that correlate only moderately with low TAWSS results. Based on clinic US examinations, results provide estimates of flow changes and forces at the carotid artery wall toward the link between hemodynamic behavior and stenosis pathophysiology. PMID:25249277

  11. 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

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

    PubMed Central

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

    2015-01-01

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

  13. Pulsatile flow simulation in arterial vascular segments with intravascular ultrasound images.

    PubMed

    Liu, Y; Lai, Y; Nagaraj, A; Kane, B; Hamilton, A; Greene, R; McPherson, D D; Chandran, K B

    2001-10-01

    Previous studies have indicated a correlation between local variation in wall shear stress in arterial blood flow and atheroma development. The purpose of this study was to analyze the hemodynamics in vascular segments from morphologically realistic three-dimensional (3D) reconstruction, and to compare the computed wall shear stress in a compliant vascular segment model and the corresponding rigid walled model. Cross-sectional images of the segments of femoral and carotid arteries in five Yucatan miniswine were obtained using intravascular ultrasound (IVUS) imaging and the segment geometry was reconstructed at different times in the cardiac cycle. The actual measured wall motion from the reconstruction was employed to specify the moving boundaries for simulation of physiological distensibility. Velocity profiles and wall shear stress were computed using unsteady computational fluid dynamics analysis. The computed results revealed that the maximum wall shear stress in the compliant model was approximately 4-17 percent less than that in the rigid model if the wall motion is larger than 10 percent. Our analysis demonstrates that inaccuracies due to inflow velocity profile can be minimized by the extension of the model upstream. The phase angle between the diameter change and wall shear is affected by the local changes in geometry of the arteries. These simulations can be potentially used to analyze the effect of regional wall motion changes in the presence of atherosclerotic lesions on the local fluid dynamics and to correlate the same with subsequent growth of the lesions. PMID:11719081

  14. 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.

  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. Image quality in obese patients undergoing 256-row computed tomography coronary angiography.

    PubMed

    Segev, Orit Lesman; Gaspar, Tamar; Halon, David A; Peled, Nathan; Domachevsky, Liran; Lewis, Basil S; Rubinshtein, Ronen

    2012-03-01

    To evaluate, objectively and subjectively, the feasibility of 256-row computed tomography coronary angiography (CTCA) in obese patients. 256-row CTCA was performed in 68 symptomatic patients (age 61 ± 10 years, 37 females), 39 obese (body mass index-BMI > 30 kg/m(2)) and 29 non-obese. Retrospective analysis was performed by two observers who assessed the image quality of each coronary segment using a 4-point subjective scale (1 excellent to 4 non-diagnostic), and another blinded observer measured objective image parameters. BMI in the obese group was 35 ± 5 (32-65) Kg/m(2), and 24 ± 3 (16-29) Kg/m(2) in the non-obese (P = 0.004). Average subjective image quality was similar in obese (1.41 ± 0.40) and non-obese (1.34 ± 0.40) patients, P = 0.17. Proportion of coronary artery segments with non-diagnostic image quality was low in both groups (0.7% in obese and 0.2% in non-obese, P = 0.31). Signal to noise and contrast to noise ratios were not significantly lower in obese than in non-obese patients (9.4 ± 3 vs. 12 ± 2.5, P = 0.16 and 11.1 ± 3.8 vs. 13.7 ± 2.9, P = 0.07 respectively). However, dose length product (1167 ± 567 vs. 827 ± 375 mGy × cm, P = 0.014) and image noise (44 ± 13 vs. 35 ± 5 HU, P < 0.001) were higher in the obese patient group. Image quality was preserved in obese patients undergoing 256-row CTCA at the cost of increased radiation exposure and image noise. PMID:21424151

  17. 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.

  18. Optical imaging of resting-state functional connectivity in a novel arterial stiffness model

    PubMed Central

    Guevara, Edgar; Sadekova, Nataliya; Girouard, Hélène; Lesage, Frédéric

    2013-01-01

    This study aims to assess the impact of unilateral increases in carotid stiffness on cortical functional connectivity measures in the resting state. Using a novel animal model of induced arterial stiffness combined with optical intrinsic signals and laser speckle imaging, resting state functional networks derived from hemodynamic signals are investigated for their modulation by isolated changes in stiffness of the right common carotid artery. By means of seed-based analysis, results showed a decreasing trend of homologous correlation in the motor and cingulate cortices. Furthermore, a graph analysis indicated a randomization of the cortex functional networks, suggesting a loss of connectivity, more specifically in the motor cortex lateral to the treated carotid, which however did not translate in differentiated metabolic activity. PMID:24298398

  19. 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

  20. Functional magnetic resonance imaging of awake monkeys: some approaches for improving imaging quality

    E-print Network

    Roe, Anna Wang

    quality Gang Chena, b, c, 1 , Feng Wangb, c, 1 , Barbara C. Dillenburgerb, c, 2 , Robert M. Friedmana , Li procedures to improve image quality with encouraging results. We evaluated the influence of two main

  1. 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.

  2. A method for 3D reconstruction of coronary arteries using biplane angiography and intravascular ultrasound images.

    PubMed

    Bourantas, Christos V; Kourtis, Iraklis C; Plissiti, Marina E; Fotiadis, Dimitrios I; Katsouras, Christos S; Papafaklis, Michail I; Michalis, Lampros K

    2005-12-01

    The aim of this study is to describe a new method for the three-dimensional reconstruction of coronary arteries and its quantitative validation. Our approach is based on the fusion of the data provided by intravascular ultrasound images (IVUS) and biplane angiographies. A specific segmentation algorithm is used for the detection of the regions of interest in intravascular ultrasound images. A new methodology is also introduced for the accurate extraction of the catheter path. In detail, a cubic B-spline is used for approximating the catheter path in each biplane projection. Each B-spline curve is swept along the normal direction of its X-ray angiographic plane forming a surface. The intersection of the two surfaces is a 3D curve, which represents the reconstructed path. The detected regions of interest in the IVUS images are placed perpendicularly onto the path and their relative axial twist is computed using the sequential triangulation algorithm. Then, an efficient algorithm is applied to estimate the absolute orientation of the first IVUS frame. In order to obtain 3D visualization the commercial package Geomagic Studio 4.0 is used. The performance of the proposed method is assessed using a validation methodology which addresses the separate validation of each step followed for obtaining the coronary reconstruction. The performance of the segmentation algorithm was examined in 80 IVUS images. The reliability of the path extraction method was studied in vitro using a metal wire model and in vivo in a dataset of 11 patients. The performance of the sequential triangulation algorithm was tested in two gutter models and in the coronary arteries (marked with metal clips) of six cadaveric sheep hearts. Finally, the accuracy in the estimation of the first IVUS frame absolute orientation was examined in the same set of cadaveric sheep hearts. The obtained results demonstrate that the proposed reconstruction method is reliable and capable of depicting the morphology of coronary arteries. PMID:16278063

  3. Image quality assessment using full-parameter singular value decomposition

    NASA Astrophysics Data System (ADS)

    Wang, Rui; Cui, Yu-Zhu; Yuan, Yan

    2011-05-01

    A new full-parameter singular value decomposition-based image quality assessment (IQA) method, which aims at capturing the loss of structural content instead of measuring the distortion of pixel intensity value, is proposed. Both the singular vectors and the singular value are considered as features and weight for quantifying major information, respectively, to evaluate the distortion degree in images. Extensive validation experiments are conducted with two kinds of test images, one of which is the LIVE database supplied by the University of Texas and the other is created from our own simulation. The prediction performance of the presented metrics, such as accuracy, monotonicity, and consistency, is measured. The experiment results show that, compared to several state-of-the-art image quality metrics, the performance of the proposed IQA is in better alignment with the perception of the human visual system in predicting image quality, particularly when comparing images containing different types of distortions.

  4. 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.

  5. Image quality analysis of compressed synthetic aperture radar imagery

    NASA Astrophysics Data System (ADS)

    Kuperman, Gilbert G.; Penrod, Todd D.

    1993-01-01

    The study investigated the effects of image compression processing on synthetic aperture radar imagery. Image quality measurements were performed before and after compression. Image fidelity measurements were made comparing the compressed and original versions of each image. Operator performance was assessed using an interpretability rating scale. Possible effects of an interaction between compression and automatic target recognizer performance were explored using a generic constant false alarm rate automatic target cuer algorithm.

  6. 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, E-mail: rvdgeest@lumc.nl [Department of Radiology, Division of Image Processing, Leiden University Medical Center, 2300 RC Leiden (Netherlands); Klein, S. [Department of Radiology and Department of Medical Informatics, Biomedical Imaging Group Rotterdam, Erasmus MC, Rotterdam 3015 GE (Netherlands)] [Department of Radiology and Department of Medical Informatics, Biomedical Imaging Group Rotterdam, Erasmus MC, Rotterdam 3015 GE (Netherlands); Kwee, R. M.; Kooi, M. E. [Department of Radiology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht 6202 AZ (Netherlands)] [Department of Radiology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht 6202 AZ (Netherlands)

    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.

  7. 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

  8. Characterization of the image-derived carotid artery input function using independent component analysis for the quantitation of [18F] fluorodeoxyglucose positron emission tomography images

    NASA Astrophysics Data System (ADS)

    Chen, K.; Chen, X.; Renaut, R.; Alexander, G. E.; Bandy, D.; Guo, H.; Reiman, E. M.

    2007-12-01

    We previously developed a noninvasive technique for the quantification of fluorodeoxyglucose (FDG) positron emission tomography (PET) images using an image-derived input function obtained from a manually drawn carotid artery region. Here, we investigate the use of independent component analysis (ICA) for more objective identification of the carotid artery and surrounding tissue regions. Using FDG PET data from 22 subjects, ICA was applied to an easily defined cubical region including the carotid artery and neighboring tissue. Carotid artery and tissue time activity curves and three venous samples were used to generate spillover and partial volume-corrected input functions and to calculate the parametric images of the cerebral metabolic rate for glucose (CMRgl). Different from a blood-sampling-free ICA approach, the results from our ICA approach are numerically well matched to those based on the arterial blood sampled input function. In fact, the ICA-derived input functions and CMRgl measurements were not only highly correlated (correlation coefficients >0.99) to, but also highly comparable (regression slopes between 0.92 and 1.09), with those generated using arterial blood sampling. Moreover, the reliability of the ICA-derived input function remained high despite variations in the location and size of the cubical region. The ICA procedure makes it possible to quantify FDG PET images in an objective and reproducible manner. Image-derived input function by ICA for FDG-PET.

  9. WAVELET-BASED FOVEATED IMAGE QUALITY MEASUREMENT FOR REGION OF INTEREST IMAGE CODING

    E-print Network

    Wang, Zhou

    resolution images. These metrics are not appropriate for the assessment of ROI coded images, where space-variant is that the human visual system (HVS) is highly space-variant in sampling, coding, processing and understandingWAVELET-BASED FOVEATED IMAGE QUALITY MEASUREMENT FOR REGION OF INTEREST IMAGE CODING Zhou Wang1

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

    NASA Astrophysics Data System (ADS)

    Pinto, Guilherme O.; Hemami, Sheila S.

    2013-03-01

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

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

    SciTech Connect

    Sailer, Johannes, E-mail: johannes.sailer@univie.ac.at; Rand, Thomas [University of Vienna, Department of Angiography and Interventional Radiology (Austria); Berg, Andreas [University of Vienna, Institute for Medical Physics (Austria); Sulzbacher, Irene [University of Vienna, Clinical Institute of Pathology (Austria); Peloschek, P. [University of Vienna, Department of Angiography and Interventional Radiology (Austria); Hoelzenbein, Thomas [University of Vienna, Department of Surgery (Austria); Lammer, Johannes [University of Vienna, Department of Angiography and Interventional Radiology (Austria)

    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.

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

    Cancer.gov

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

  13. 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.

  14. Biomarker, Imaging and Quality of LIfe Studies Funding Program (BIQSFP)

    Cancer.gov

    Funded Cooperative Groups (CGs) and funded Community Clinical Oncology Program (CCOP) Research Bases are invited to apply for funding to support essential biomarker, imaging, and quality of life studies which are associated with clinical trial concepts.

  15. A fast analysis method for non-invasive imaging of blood flow in individual cerebral arteries using vessel-encoded arterial spin labelling angiography

    PubMed Central

    Chappell, Michael A.; Okell, Thomas W.; Payne, Stephen J.; Jezzard, Peter; Woolrich, Mark W.

    2012-01-01

    Arterial spin labelling (ASL) MRI offers a non-invasive means to create blood-borne contrast in vivo for dynamic angiographic imaging. By spatial modulation of the ASL process it is possible to uniquely label individual arteries over a series of measurements, allowing each to be separately identified in the resulting angiographic images. This separation requires appropriate analysis for which a general Bayesian framework has previously been proposed. Here this framework is adapted for clinical dynamic angiographic imaging. This specifically addresses the issues of computational speed of the algorithm and the robustness required to deal with real patient data. An algorithm is proposed that can incorporate planning information about the arteries being imaged whilst adapting for subsequent patient movement. A fast maximum a posteriori solution is adopted and shown to be only marginally less accurate than Monte Carlo sampling under simulation. The final algorithm is demonstrated on in vivo data with analysis on a time scale of the order of 10 min, from both a healthy control and a patient with a vertebro-basilar occlusion. PMID:22322066

  16. Imaging Quality Evaluation of Low Tube Voltage Coronary CT Angiography Using Low Concentration Contrast Medium

    PubMed Central

    Zhang, Zaixian; Wang, Qingguo; Zheng, Linfeng; Feng, Yan; Zhou, Zhiguo; Zhang, Guixiang; Li, Kangan

    2015-01-01

    Purpose To compare the image quality of prospectively ECG-gated low voltage coronary computed tomography angiography (CTA) with an administration of low concentration contrast medium. Method and Materials A total of 101 patients, each with a heart rate below 65 beats per minute (BPM), underwent a prospectively ECG-gated axial scan in CT coronary angiography on a 64-slice CT scanner. All patients were allocated in three groups (group A: n=31, 80kVp, 300 mgI/ml; group B: n=34, 100kVp, 300 mgI/ml; group C: n=36, 120kVp, 370 mgI/ml). The CT attenuation values of aortic root (AR), left main coronary artery (LMA), right main coronary artery (RMA) and chest subcutaneous fat tissue were measured. The contrast-to-noise ratio (CNR) of AR, LMA and RMA were calculated according to the formulas below. The values of computed tomography dose index (CTDI) and dose-length product (DLP) were recorded. Image quality was assessed on a 5-point scale. The results were compared using the one-way ANOVA and rank sum tests. Results The values of CNR and SNR for vessels in group A and group B were not significantly different from group C (each p > 0.05). The effective radiation dose in group A (1.51±0.70 mSv) and group B (2.59±1.24 mSv) were both lower than group C (4.92±2.82 mSv) (each p < 0.05). There was no significant difference among the image quality scores of group A (4.10±0.41), group B (3.90±0.48) and group C (4.04±0.36) (each P > 0.05). Conclusion Low tube voltage coronary CT angiography using low concentration contrast medium does not affect the imaging quality for assessing the coronary arteries compared with high voltage coronary CT angiography using high concentration contrast medium. Meanwhile low concentration contrast medium allowed 47-69% of radiation dose reduction. PMID:25811785

  17. 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

  18. Exercise thallium-201 imaging for risk stratification of elderly patients with coronary artery disease

    SciTech Connect

    Iskandrian, A.S.; Heo, J.; Decoskey, D.; Askenase, A.; Segal, B.L.

    1988-02-01

    Although coronary artery disease (CAD) may be asymptomatic, it is the most common cause of death in elderly patients in the U.S. This study examined the prognosis of 449 patients with a mean age of 65 years using exercise thallium-201 imaging. At a follow-up of 25 months, 45 patients underwent coronary artery revascularization, 8 died of cardiac causes and 10 had nonfatal acute myocardial infarctions (AMIs). Thus, the total of patients with ''hard'' events was 18. The events included 12 of 276 patients with atypical or non-anginal symptoms versus 6 of 128 with typical angina (p = not significant); 7 of 51 patients (14%) with Q-wave AMI versus 11 of 353 (3%) without Q-wave AMI (p less than 0.001); 1 of 183 patients (1%) with normal versus 17 of 221 (8%) with abnormal exercise thallium-201 images (p less than 0.002); 10 of 76 patients (13%) with multi vessel thallium-201 abnormality vs 8 of 328 (2%) with no or 1-vessel thallium-201 abnormality (p less than 0.001) and 10 of 96 patients (10%) with greater than or equal to 3 abnormal segments by thallium-201 imaging (total segments = 9) versus 8 of 308 patients with no or less than 3 abnormal segments (p less than 0.001). The number of segments with thallium-201 defects was 1 +/- 2 patients without and 3 +/- 2 in patients with hard events (p less than 0.002).

  19. 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.

  20. Experimental Approach for Human Perception Based Image Quality Assessment

    Microsoft Academic Search

    Jin-seo Kim; Maeng-sub Cho; Bon-ki Koo

    2006-01-01

    The term ‘image quality’ is a subject notion so it is difficult to quantify. However, it can be reasonably quantified by using\\u000a statistical and psychophysical approaches. Furthermore, it is also possible to model the human perception of image quality.\\u000a In this paper, large scale psychophysical experiments including pair comparison and categorical judgment were carried out\\u000a to judge the perception of

  1. 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.

  2. Need for an image quality assurance program in clinical teleradiology

    NASA Astrophysics Data System (ADS)

    Telepak, Robert J.; Kelsey, Charles A.

    1995-05-01

    The purpose of this paper is to report on the experience we have gained with regard to image quality assurance (QA) in a clinical teleradiology practice between a central university hub and multiple very remote rural spokes in a two state area. Identical standard SMPTE test pattern images were supplied to each remote site which digitized and transmitted them at monthly intervals to the hub for QA analysis. Many types of image quality inadequacies were detected. These included vertical artifact lines from dirt in the scanning mechanism, inadequate spatial resolution, inadequate contrast resolution, brightness imbalance, and variable distortions of the image. A predictable pattern of digitizer malfunction was not detected. While the quality of some sites remained relatively stable over many months, others deteriorated rapidly. We conclude that a continuous QA image screening program is essential in a hub and spoke teleradiology operation with the type and interval of screening depending upon multiple factors described in this paper.

  3. 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

  4. Image matting based high-quality stereo view synthesis

    NASA Astrophysics Data System (ADS)

    Kannan, Hariprasad; Iyer, Kiran N.; Maiti, Kausik; Purbiya, Devendra; Bopardikar, Ajit; Sharma, Anshul

    2010-07-01

    The commercial success and acceptability of 3D technology will critically depend on the overall visual quality of the rendered images. Therefore Depth Image Based Rendering (DIBR) is a crucial component of the 3D system chain. In this paper, we describe a high quality DIBR system for view synthesis. In particular, a procedure is outlined for the processing of the so-called mixed pixels at object boundaries. A Layered Depth Image (LDI) representation of the scene is obtained given an image and corresponding depth map. In the process, all significant mixed pixels in the image are automatically separated into their local foreground and local background. Our results show superior rendering quality, especially at object edges.

  5. Toward high-quality image communications: inverse problems in image processing

    NASA Astrophysics Data System (ADS)

    Jung, Cheolkon; Jiao, Licheng; Liu, Bing; Qi, Hongtao; Sun, Tian

    2012-10-01

    Recently, image communications are becoming increasingly popular, and there is a growing need for consumers to be provided with high-quality services. Although the image communication services already exist over third-generation wireless networks, there are still obstacles that prevent high-quality image communications because of limited bandwidth. Thus, more research is required to overcome the limited bandwidth of current communications systems and achieve high-quality image reconstruction in real applications. From the point of view of image processing, core technologies for high-quality image reconstruction are face hallucination and compression artifact reduction. The main interests of consumers are facial regions and several compression artifacts inevitably occur by compression; these two technologies are closely related to inverse problems in image processing. We review recent studies on face hallucination and compression artifact reduction, and provide an outline of current research. Furthermore, we discuss practical considerations and possible solutions to implement these two technologies in real mobile applications.

  6. Renal Advances in Ultrasound Elasticity Imaging: Measuring the Compliance of Arteries and Kidneys in End-Stage Renal Disease

    Microsoft Academic Search

    W. F. Weitzel; K. Kim; J. M. Rubin; H. Xie; M. O’Donnell

    2005-01-01

    Background\\/Aims: Ultrasound elasticity imaging visually represents tissue hardness measurements using high-resolution ultrasound speckle-tracking algorithms. This method has recently been applied in the renal setting to measure arterial compliance in end-stage renal disease (ESRD) and the mechanical properties of transplant kidneys in vivo. Methods: Ultrasound radio-frequency signal measurements were made of the brachial artery in 5 ESRD subjects and 5 healthy

  7. Cerebral Artery–Vein Separation Using 0.1Hz Oscillation in Dual-Wavelength Optical Imaging

    Microsoft Academic Search

    Yucheng Wang; Dewen Hu; Yadong Liu; Ming Li

    2011-01-01

    We present a novel artery-vein separation method using 0.1-Hz oscillation at two wavelengths with optical imaging of intrinsic signals (OIS). The 0.1-Hz oscillation at a green light wavelength of 546 nm exhibits greater amplitude in arteries than in veinsand isprimarily caused by vasomotion,whereas the 0.1-Hz oscillation at a red light wavelength of 630 nm exhibits greater amplitude in veins than

  8. Utilizing image scales towards totally training free blind image quality assessment.

    PubMed

    Saha, Ashirbani; Wu, Qing Ming Jonathan

    2015-06-01

    A new approach to blind image quality assessment (BIQA), requiring no training, is proposed in this paper. The approach is named as blind image quality evaluator based on scales and works by evaluating the global difference of the query image analyzed at different scales with the query image at original resolution. The approach is based on the ability of the natural images to exhibit redundant information over various scales. A distorted image is considered as a deviation from the natural image and bereft of the redundancy present in the original image. The similarity of the original resolution image with its down-scaled version will decrease more when the image is distorted more. Therefore, the dissimilarities of an image with its low-resolution versions are cumulated in the proposed method. We dissolve the query image into its scale-space and measure the global dissimilarity with the co-occurrence histograms of the original and its scaled images. These scaled images are the low pass versions of the original image. The dissimilarity, called low pass error, is calculated by comparing the low pass versions across scales with the original image. The high pass versions of the image in different scales are obtained by Wavelet decomposition and their dissimilarity from the original image is also calculated. This dissimilarity, called high pass error, is computed with the variance and gradient histograms and weighted by the contrast sensitivity function to make it perceptually effective. These two kinds of dissimilarities are combined together to derive the quality score of the query image. This method requires absolutely no training with the distorted image, pristine images, or subjective human scores to predict the perceptual quality but uses the intrinsic global change of the query image across scales. The performance of the proposed method is evaluated across six publicly available databases and found to be competitive with the state-of-the-art techniques. PMID:25775489

  9. Atherosclerosis in angiographically “normal” coronary artery reference segments: An intravascular ultrasound study with clinical correlations

    Microsoft Academic Search

    Gary S. Mintz; Jack A. Painter; Augusto D. Pichard; Kenneth M. Kent; Lowell F. Satler; Jeffrey J. Popma; Ya Chien Chuang; Theresa A. Bucher; Lisa E. Sokolowicz; Martin B. Leon

    1995-01-01

    Objectives. This study evaluated the magnitude, patterns and clinical correlates of atherosclerosis in angiographically “normal” reference segments in patients undergoing transcatheter therapy for symptomatic coronary artery disease.Background. Pathologic studies indicate that the extent of coronary atherosclerosis is underestimated by visual analysis of angiographically normal coronary artery segments. Intravascular ultrasound allows detailed, high quality cross-sectional imaging of the coronary arteries in

  10. Relationship of subjective ratings of image quality and observer performance

    Microsoft Academic Search

    Howard E. Rockette; Christopher M. Johns; Jane L. Weissman; J. Michael Holbert; Jules H. Sumkin; Jill L. King; David Gur

    1997-01-01

    The relationship between radiologists' perception of image quality and their actual performance was assessed. If the two variables are strongly correlated, the easier obtained perception of quality index might be used as a prerequisite test to determine if a ROC study is justified. One-hundred seventy cases were evaluated for the presence or absence of interstitial disease and nodules by nine

  11. Customer satisfaction, corporate image, and service quality in professional services

    Microsoft Academic Search

    Mara Cameran; Peter Moizer; Angela Pettinicchio

    2010-01-01

    This study explores the impact of corporate image and service quality on customer satisfaction in the professional service industries. Data were collected on audit firms, sending a questionnaire to financial executives of leading Italian companies. The results show that the most important variable explaining customer satisfaction was the apparent effectiveness of the audit firm. In relation to service quality, managers'

  12. Quality Grade-Testing of Peanut Based on Image Processing

    Microsoft Academic Search

    Han Zhong-zhi; Li Yan-zhao; Liu Jing; Zhao You-gang

    2010-01-01

    The quality of peanut kernels is referred to the every aspect of the profit of supply and marketing. A BP neural network model of quality grade testing and identification is built which is based on 52 appearance features such as the form, texture, and color and so on with technology of computer image processing. The testing aiming at 1400 grains

  13. 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?images was almost perfect (??=?0.891, p?artery SNR and CNR when compared to both RV-wFBP and SV-CTPA. PMID:24993583

  14. 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.

  15. 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

  16. Evaluation of resistive index using color Doppler imaging of orbital arteries in geriatric patients with hypertension

    PubMed Central

    Akal, Ali; Ulas, Turgay; Goncu, Tugba; Karakas, Ekrem; Karakas, Omer; Kurnaz, Fatih; Boyaci, Fatima Nurefsan; Yilmaz, Omer Faruk; Bata, Abdulgafur; Yildiz, Sema

    2014-01-01

    Background and Aim: Resistive index (RI) is an indirect measurement of blood flow resistance that can be used to evaluate vascular damage in ophthalmologic disease. The purpose of this study was to evaluate the association between RI values of orbital arteries using the color Doppler imaging (CDI) in geriatric hypertensive patients with or without retinopathy. Setting and Design: Designed as a cross-sectional study. Materials and Methods: We evaluated 60 geriatric patients with hypertension (Group 1) and 30 healthy subjects (Group 2). Further, the patients with hypertension were grouped into two: Group 1a consisted of patients with retinopathy (n = 30), and group 1b consisted of patients without retinopathy (n = 30). The mean RI values of ophthalmic artery (OA), central retinal artery (CRA), and posterior ciliary artery (PCA) were measured using CDI. Results: Compared to group 2, group 1 had significantly higher mean resistive index of PCA levels (P = 0.017), whereas there were no statistical difference in mean resistive indexes of OA and CRA (both P > 0.05). Besides, there were no statistical difference in mean resistive indexes of OA, CRA, and PCA between the group 1a and group 1b (P > 0.05 for all). Mean resistive indexes of OA, CRA, and PCA were significantly correlated with the duration of hypertension (r = 0.268, P = 0.038; r = 0.315, P = 0.014; r = 0.324, P = 0.012, respectively). Conclusions: Our study indicates that RI might be a useful marker for the ocular hemodynamic of retinal vessels, provides morphologic and vascular information in hypertension and hypertensive retinopathy. PMID:25005192

  17. 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

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

    PubMed

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

    2014-03-01

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

  19. RIS-M-2170 COMPARISON OP IMAGE QUALITY

    E-print Network

    RISÃ?-M-2170 COMPARISON OP IMAGE QUALITY OP NUCLEAR FUEL NEUTRON RADIOGRAPHS TAKEN ON SILVER HALIDE AND NITROCELLULOSE FILM J.C. DOMAMUS Metallurgy Department Abstract. Paper accepted for presentation on 19.11.1979 to the Ninth World Conference on Non-Destructive Testing in Melbourne, Australia. For the assessment of image

  20. A new quality metric for compressed images based on DDCT

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

    As the performance-indicator of the image processing algorithms or systems, image quality assessment (IQA) has attracted the attention of many researchers. Aiming to the widely used compression standards, JPEG and JPEG2000, we propose a new no reference (NR) metric for compressed images to do IQA. This metric exploits the causes of distortion by JPEG and JPEG2000, employs the directional discrete cosine transform (DDCT) to obtain the detail and direction information of the images and incorporates with the visual perception to obtain the image quality index. Experimental results show that the proposed metric not only has outstanding performance on JPEG and JPEG2000 images, but also applicable to other types of artifacts.

  1. Hepatic Arterial Phase on Gadoxetic Acid-Enhanced Liver MR Imaging: A Randomized Comparison of 0.5 mL/s and 1 mL/s Injection Rates

    PubMed Central

    Kim, Sung Mo; Heo, Suk Hee; Kim, Jin Woong; Lim, Hyo Soon; Shin, Sang Soo; Kang, Heoung Keun

    2014-01-01

    Objective To compare gadoxetic acid injection rates of 0.5 mL/s and 1 mL/s for hepatic arterial-phase magnetic resonance (MR) imaging. Materials and Methods In this prospective study, 101 consecutive patients with suspected focal liver lesions were included and randomly divided into two groups. Each group underwent dynamic liver MR imaging using a 3.0-T scanner after an intravenous injection of gadoxetic acid at rates of either 0.5 mL/s (n = 50) or 1 mL/s (n = 51). Arterial phase images were analyzed after blinding the injection rates. The signal-to-noise ratios (SNRs) of the liver, aorta, portal vein, hepatic vein, spleen, and pancreas were measured. The contrast-to-noise ratios (CNRs) of the hepatocellular carcinomas (HCC) were calculated. Finally, two experienced radiologists were independently asked to identify, if any, HCCs in the liver on the images and score the image quality in terms of the presence of artifacts and the proper enhancement of the liver, aorta, portal vein, hepatic vein, hepatic artery, spleen, pancreas, and kidney. Results The SNRs were not significantly different between the groups (p = 0.233-0.965). The CNRs of the HCCs were not significantly different (p = 0.597). The sensitivity for HCC detection and the image quality scores were not significantly different between the two injection rates (p = 0.082-1.000). Conclusion Image quality and sensitivity for hepatic HCCs of arterial-phase gadoxetic acid-enhanced MR were not significantly improved by reducing the contrast injection rate to 0.5 mL/s compared with 1 mL/s. PMID:25246821

  2. Buildup of Image Quality in View-Shared Time-Resolved 3D CE-MRA

    PubMed Central

    Johnson, Casey P.; Polley, Thomas W.; Glockner, James F.; Young, Phillip M.; Riederer, Stephen J.

    2012-01-01

    Time-resolved 3D contrast-enhanced MR angiography (CE-MRA) often relies on view sharing of peripheral k-space data to enable acquisition of angiograms with both high spatial resolution and a rapid frame rate. It is typically assumed that k-space will be fully sampled during passage of the contrast bolus arterial phase. However, this is not the case when view sharing is incomplete, for example at the leading edge of an enhancing vessel or if acquisition time is limited as in fluoroscopic tracking for multi-station bolus chase MRA. Incomplete view sharing will degrade image quality, for example by reducing vessel signal and sharpness and increasing undersampling artifacts. In this work, the evolution of angiogram quality with view sharing is quantitatively assessed in phantom experiments and in vivo CE-MRA calf studies. It is demonstrated that there are multiple sets of sequence parameters that can yield a target image update time, but the choice of parameters can profoundly affect how image quality evolves with view sharing. A fundamental tradeoff between vessel signal and sharpness and its relationship to the sequence temporal footprint is investigated and discussed. PMID:22936574

  3. Digital radiography: image quality and radiation dose.

    PubMed

    Seibert, J Anthony

    2008-11-01

    Digital radiography devices, rapidly replacing analog screen-film detectors, are now common in diagnostic radiological imaging, where implementation has been accelerated by the commodity status of electronic imaging and display systems. The shift from narrow latitude, fixed-speed screen-film detectors to wide latitude, variable-speed digital detectors has created a flexible imaging system that can easily result in overexposures to the patient without the knowledge of the operator, thus potentially increasing the radiation burden of the patient population from radiographic examinations. In addition, image processing can be inappropriately applied causing inconsistent or artifactual appearance of anatomy, which can lead to misdiagnosis. On the other hand, many advantages can be obtained from the variable-speed digital detector, such as an ability to lower dose in many examinations, image post-processing for disease-specific conditions, display flexibility to change the appearance of the image and aid the physician in making a differential diagnosis, and easy access to digital images. An understanding of digital radiography is necessary to minimize the possibility of overexposures and inconsistent results, and to achieve the principle of as low as reasonably achievable (ALARA) for the safe and effective care of all patients. Thus many issues must be considered for optimal implementation of digital radiography, as reviewed in this article. PMID:18849693

  4. Quality evaluation of extra high quality images based on key assessment word

    NASA Astrophysics Data System (ADS)

    Kameda, Masashi; Hayashi, Hidehiko; Akamatsu, Shigeru; Miyahara, Makoto M.

    2001-06-01

    An all encompassing goal of our research is to develop an extra high quality imaging system which is able to convey a high level artistic impression faithfully. We have defined a high order sensation as such a high level artistic impression, and it is supposed that the high order sensation is expressed by the combination of the psychological factor which can be described by plural assessment words. In order to pursue the quality factors that are important for the reproduction of the high order sensation, we have focused on the image quality evaluation of the extra high quality images using the assessment words considering the high order sensation. In this paper, we have obtained the hierarchical structure between the collected assessment words and the principles of European painting based on the conveyance model of the high order sensation, and we have determined a key assessment word 'plasticity' which is able to evaluate the reproduction of the high order sensation more accurately. The results of the subjective assessment experiments using the prototype of the developed extra high quality imaging system have shown that the obtained key assessment word 'plasticity' is the most appropriate assessment word to evaluate the image quality of the extra high quality images quasi-quantitatively.

  5. Improved image quality with Bayesian image processing in digital mammography

    NASA Astrophysics Data System (ADS)

    Baydush, Alan H.; Floyd, Carey E., Jr.

    2000-06-01

    Recent developments in digital detectors have led to investigating the importance of grids in mammography. We propose to examine the use Bayesian Image Estimation (BIE) as a software means of removing scatter post acquisition and to compare this technique to a grid. BIE is an iterative, non- linear statistical estimation technique that reduces scatter content while improving CNR. Images of the ACR breast phantom were acquired both with and without a grid on a calibrated digital mammography system. A BIE algorithm was developed and was used to process the images acquired without the grid. Scatter fractions (SF) were compared for the image acquired with the grid, the image acquired without the grid, and the image acquired without the grid and processed by BIE. Images acquired without the anti-scatter grid had an initial SF of 0.46. Application of the Bayesian image estimation technique reduced this to 0.03. In comparison, the use of the grid reduced the SF to 0.19. The use of Bayesian image estimation in digital mammography is beneficial in reducing scatter fractions. This technique is very useful as it can reduce scatter content effectively without introducing any adverse effects such as aliasing caused by gridlines.

  6. A new method for quality assessment of hyperspectral images

    Microsoft Academic Search

    A. Garzelli; F. Nencini; L. Alparone; S. Baronti

    2007-01-01

    This work focuses on quality assessment of fusion of hyperspectral (HS) images with high-resolution panchromatic (Pan) data. A novel fidelity index suitable for HS images is defined from the theory of hypercomplex numbers (2n-ons). Both spectral and spatial distortion measurements are encapsulated in a unique score index. Some fusion methods capable to selectivity inject spatial-frequencies from the higher-resolution Pan image

  7. 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

  8. Bio-inspired framework for automatic image quality enhancement

    NASA Astrophysics Data System (ADS)

    Ceresi, Andrea; Gasparini, Francesca; Marini, Fabrizio; Schettini, Raimondo

    2012-01-01

    We propose a bio-inspired framework for automatic image quality enhancement. Restoration algorithms usually have fixed parameters whose values are not easily settable and depend on image content. In this study, we show that it is possible to correlate no-reference visual quality values to specific parameter settings such that the quality of an image could be effectively enhanced through the restoration algorithm. In this paper, we chose JPEG blockiness distortion as a case study. As for the restoration algorithm, we used either a bilateral filter, or a total variation denoising detexturer. The experimental results on the LIVE database will be reported. These results will demonstrate that a better visual quality is achieved through the optimized parameters over the entire range of compression, with respect to the algorithm default parameters.

  9. ISO 20462: a psychophysical image quality measurement standard

    NASA Astrophysics Data System (ADS)

    Keelan, Brian W.; Urabe, Hitoshi

    2003-12-01

    ISO 20462, a three-part standard entitled "Psychophysical experimental methods to estimate image quality," is being developed by WG18 (Electronic Still Picture Imaging) of TC42 (Photography). As of late 2003, all three parts were in the Draft International Standard (DIS) ballot stage, with publication likely during 2004. This standard describes two novel perceptual methods, the triplet comparison technique and the quality ruler, that yield results calibrated in just noticeable differences (JNDs). Part 1, "Overview of psychophysical elements," discusses specifications regarding observers, test stimuli, instructions, viewing conditions, data analysis, and reporting of results. Part 2, "Triplet comparison method," describes a technique involving simultaneous five-point scaling of sets of three stimuli at a time, arranged so that all possible pairs of stimuli are compared exactly once. Part 3, "Quality ruler method," describes a real-time technique optimized for obtaining assessments over a wider range of image quality. A single ruler is a series of ordered reference stimuli depicting a common scene but differing in a single perceptual attribute. Methods for generating quality ruler stimuli of known JND separation through modulation transfer function (MTF) variation are provided. Part 3 also defines a unique absolute Standard Quality Scale (SQS) of quality with one unit equal to one JND. Standard Reference Stimuli (SRS) prints calibrated against this new scale will be made available through the International Imaging Industry Association.

  10. Uterine artery embolization: pre- and post-procedural evaluation using magnetic resonance imaging.

    PubMed

    Siddiqui, Nasir; Nikolaidis, Paul; Hammond, Nancy; Miller, Frank H

    2013-10-01

    Magnetic resonance (MR) imaging has become the preferred method in assessing the uterus and pelvis prior to and following uterine artery embolization (UAE). The multiplanar imaging capabilities, increased spatial and contrast resolution, anatomic detail and assessment of fibroid viability that MR provides over ultrasound allows for accurate pre-treatment planning and post-treatment assessment. The purpose of this article is to demonstrate the use of MR in the selection of patients, anatomic evaluation and procedural planning before UAE, describe the use of MR in evaluating treatment response after UAE and illustrate the use of MR in identifying post-UAE complications. An understanding of these principles is essential in guiding appropriate therapy, determining treatment effectiveness and identifying associated complications before and after UAE. PMID:23471598

  11. 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.

  12. Multidetector-row computed tomography and magnetic resonance imaging of atherosclerotic lesions in human ex vivo coronary arteries

    Microsoft Academic Search

    Konstantin Nikolaou; Christoph R Becker; Michael Muders; Gregor Babaryka; Juergen Scheidler; Thomas Flohr; Udo Loehrs; Maximilian F Reiser; Zahi A Fayad

    2004-01-01

    In the present study, we tested the ability of multidetector-row computed tomography (MDCT) and magnetic resonance imaging (MRI) to identify and retrospectively characterize atherosclerotic lesions in human ex vivo coronary arteries. Thirteen ex vivo hearts were studied with MDCT and MRI. MDCT-images were obtained with an isotropic voxel size of 0.6mm3. MR images were obtained with an in-plane resolution of

  13. Prospective study of health related quality of life before and after coronary artery bypass grafting: outcome at five years

    Microsoft Academic Search

    N Caine; L D Sharples; J Wallwork

    1999-01-01

    OBJECTIVETo determine the long term health related quality of life of coronary artery bypass graft patients, to look at changes between one and five years after surgery, and to examine the ability of preoperative variables to predict longer term outcome.DESIGNNottingham health profile (NHP) was used to assess patients at five years compared to results obtained at one year.PATIENTS100 male patients

  14. Predictors of poor mid-term health related quality of life after primary isolated coronary artery bypass grafting surgery

    Microsoft Academic Search

    S Al-Ruzzeh; T Athanasiou; O Mangoush; J Wray; T Modine; S George; M Amrani

    2005-01-01

    Objective: To assess the determinants of poor mid-term health related quality of life (HRQoL) at one year after primary isolated coronary artery bypass grafting (CABG).Methods: 463 patients who underwent primary isolated CABG for multivessel disease and came for their annual follow up at the outpatient clinic during one year at Harefield Hospital, Middlesex, were approached to participate in the present

  15. 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

  16. 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.

  17. 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 (NIH)

    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.

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

    PubMed

    Zhou, Xiaolin; Bedggood, Phillip; Metha, Andrew

    2014-08-01

    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

  19. 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

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

    PubMed

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

    2015-03-01

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

  1. Maintaining image quality when watermarking grayscale comic images for electronic books

    Microsoft Academic Search

    Takaaki Yamada; Ryu Ebisawa; Yoshiyasu Takahashi

    2011-01-01

    Digital watermarking of comic images effectively protects the copyright of the content in electronic book applications. The characteristics of comic images were analyzed to determine the effect of digital watermarking on the line shapes. Modification of the shape edges by conventional watermarking methods can degrade image quality because the human eye is sensitive to the edges. The analysis revealed that

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Evidence quality imaging for bank security

    Microsoft Academic Search

    P. Gallagher; S. Doyle

    1995-01-01

    A long standing problem within the banking security and law enforcement communities has been the inability to use the images recorded with conventional security cameras as definitive evidence in a court of law. The issue with affordable solid state or tube security cameras is the spatial resolution and gray scale resolution. Neither is sufficient. Alternatives using film cameras have proved

  7. LANDSAT-4 image data quality analysis

    NASA Technical Reports Server (NTRS)

    Anuta, P. E.

    1984-01-01

    Methods were developed for estimating point spread functions from image data. Roads and bridges in dark backgrounds are being examined as well as other smoothing methods for reducing noise in the estimated point spread function. Tomographic techniques were used to estimate two dimensional point spread functions. Reformatting software changes were implemented to handle formats for LANDSAT-5 data.

  8. Image-Quality-Based Adaptive Face Recognition

    Microsoft Academic Search

    Harin Sellahewa; Sabah A. Jassim

    2010-01-01

    The accuracy of automated face recognition systems is greatly affected by intraclass variations between enrollment and identification stages. In particular, changes in lighting conditions is a major contributor to these variations. Common approaches to address the effects of varying lighting conditions include preprocessing face images to normalize intraclass variations and the use of illumination invariant face descriptors. Histogram equalization is

  9. 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

  10. 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.

  11. 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.

  12. Quality of Life, Safety and Efficacy Profile of Thermostable Flolan in Pulmonary Arterial Hypertension

    PubMed Central

    2015-01-01

    Background Flolan (epoprostenol sodium) is most commonly prescribed to patients with severe pulmonary arterial hypertension (PAH) owing to the requirement that the drug be delivered by continuous intravenous infusion and the reconstituted solution may only be administered up to 24 hours when it is maintained between a temperature of 2°C and 8°C. The aim of this single-arm, open label study was to describe the effects of the new thermostable formulation of Flolan on health-related quality of life (HRQoL) and ease of administration in subjects switching from the currently marketed Flolan to the reformulated product. Methods Following a 4-week run-in period and after 4 weeks of treatment with the reformulated product, patients completed the SF-36 HRQoL questionnaire and a study-specific questionnaire evaluating ease of administration, along with World Health Organization (WHO) functional class, six-minute walked distance (6MWD) and N-terminal-pro B-type natriuretic peptide (NT-proBNP) assessment. Results 16 participants completed the study. The SF-36 scores remained unchanged from baseline to Week 4. Conversely, there were small improvements for the majority of the study-specific questionnaire items and 14 (88%) subjects preferred the reformulated product to the currently marketed Flolan. There was no significant change in the dose of reformulated product, 6MWD, Borg dyspnoea index, WHO functional class and mean NT-proBNP levels. No significant changes in haemodynamic parameters were seen from baseline to 2 hours post transition in a subset of patients undergoing catheterization. Conclusion The reformulated product was not associated with significant improvement in HRQoL compared with the currently marketed Flolan as measured by the SF-36. However, most subjects preferred the reformulated product to the currently marketed Flolan. Moreover, the 2 formulations of Flolan had similar safety and efficacy profiles. Trial Registration ClinicalTrials.gov NCT01462565 PMID:25793960

  13. Follow-up outcomes 10 years after arterial switch operation for transposition of the great arteries: comparison of cardiological health status and health-related quality of life to those of the a normal reference population

    Microsoft Academic Search

    Wilfred B. de Koning; Magdalena van Osch-Gevers; A. Derk Jan Ten Harkel; Ron T. van Domburg; Alma W. Spijkerboer; Elisabeth M. W. J. Utens; Ad J. J. C. Bogers; Willem A. Helbing

    2008-01-01

    The purpose of this study was to investigate the cardiological health status and health-related quality of life after the\\u000a arterial switch operation (ASO) for transposition of the great arteries (TGA) in comparison with a normative reference group.\\u000a Chart review and cross-sectional systematic follow-up, including echocardiography, exercise testing, and electrocardiography,\\u000a were performed on all survivors of ASO for TGA between 1990

  14. Smoothing depth maps for improved steroscopic image quality

    NASA Astrophysics Data System (ADS)

    Tam, Wa James; Alain, Guillaume; Zhang, Liang; Martin, Taali; Renaud, Ronald

    2004-10-01

    A technique to improve the image quality of stereoscopic pictures generated from depth maps (depth image based rendering or DIBR) is examined. In general, there are two fundamental problems with DIBR: a depth map could contain artifacts (e.g., noise or "blockiness") and there is no explicit information on how to render newly exposed regions ("holes") in the rendered image as a result of new virtual camera positions. We hypothesized that smoothing depth maps before rendering will not only minimize the effects of noise and distortions in the depth maps but will also reduce areas of newly exposed regions where potential artifacts can arise. A formal subjective assessment of four stereoscopic sequences of natural scenes was conducted with 23 viewers. The stereoscopic sequences consisted of source images for the left-eye view and rendered images for the right-eye view. The depth maps were smoothed with a Gaussian blur filter at different levels of strength before depth image based rendering. Results indicated that ratings of perceived image quality improved with increasing levels of smoothing of the depth maps. Even though the depth maps were smoothed, a negative effect on ratings of overall perceived depth quality was not found.

  15. Thematic Mapper image quality: Preliminary results

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

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

  16. 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

  17. Digital image correlation for full-field time-resolved assessment of arterial stiffness

    NASA Astrophysics Data System (ADS)

    Campo, Adriaan; Soons, Joris; Heuten, Hilde; Ennekens, Guy; Goovaerts, Inge; Vrints, Christiaan; Lava, Pascal; Dirckx, Joris

    2014-01-01

    Pulse wave velocity (PWV) of the arterial system is a very important parameter to evaluate cardiovascular health. Currently, however, there is no golden standard for PWV measurement. Digital image correlation (DIC) was used for full-field time-resolved assessment of displacement, velocity, acceleration, and strains of the skin in the neck directly above the common carotid artery. By assessing these parameters, propagation of the pulse wave could be tracked, leading to a new method for PWV detection based on DIC. The method was tested on five healthy subjects. As a means of validation, PWV was measured with ultrasound (US) as well. Measured PWV values were between 3.68 and 5.19 m/s as measured with DIC and between 5.14 and 6.58 m/s as measured with US, with a maximum absolute difference of 2.78 m/s between the two methods. DIC measurements of the neck region can serve as a test base for determining a robust strategy for PWV detection, they can serve as reference for three-dimensional fluid-structure interaction models, or they may even evolve into a screening method of their own. Moreover, full-field, time-resolved DIC can be adapted for other applications in biomechanics.

  18. Hemodynamic instability increases new ischemic brain lesions on diffusion-weighted imaging after carotid artery stenting.

    PubMed

    Ito, Yoshiro; Kato, Noriyuki; Matsumura, Akira; Sonobe, Makoto

    2013-01-01

    Hemodynamic instability (HI) may impair the washout of debris during distal intracranial circulation and increase the risk of clinically evident cerebral ischemia. However, the interaction between HI and new ischemic brain lesions detected on diffusion-weighted imaging (DWI) has not been examined. This study evaluated whether HI was significantly associated with the incidence of new ischemic brain lesions on DWI. Data on 128 patients who underwent carotid artery stenting (CAS) with the same devices and procedures between January 2005 and May 2010 were retrospectively analyzed. HI was noted in 31 (24.2%) patients. New ischemic brain lesions were detected on DWI in 25 (19.5%) patients. Ten of 31 (32.2%) patients with HI showed new ischemic brain lesions on DWI. Fifteen of 97 (15.5%) patients without HI showed new lesions. Univariate analysis showed that patients with HI had a significantly higher incidence of new ischemic brain lesions than patients without HI (p = 0.04). A multivariable model showed that age and HI were significantly associated with the incidence of new ischemic brain lesions. In patients with carotid artery stenosis, decreased blood pressure produced no active vascular response, but reduced the cerebral blood volume and velocity due to impaired dynamic cerebral autoregulation. The results of this study suggest that HI with CAS induces impaired clearance of microembolisms and causes an increased number of new ischemic brain lesions detected on DWI. PMID:23803615

  19. Perceptually significant spatial pooling techniques for image quality assessment

    NASA Astrophysics Data System (ADS)

    Moorthy, Anush K.; Bovik, Alan C.

    2009-02-01

    Spatial pooling strategies used in recent Image Quality Assessment (IQA) algorithms have generally been that of simply averaging the values of the obtained scores across the image. Given that certain regions in an image are perceptually more important than others, it is not unreasonable to suspect that gains can be achieved by using an appropriate pooling strategy. In this paper, we explore two hypothesis that explore spatial pooling strategies for the popular SSIM metrics.1, 2 The first is visual attention and gaze direction - 'where' a human looks. The second is that humans tend to perceive 'poor' regions in an image with more severity than the 'good' ones - and hence penalize images with even a small number of 'poor' regions more heavily. The improvements in correlation between the objective metrics' score and human perception is demonstrated by evaluating the performance of these pooling strategies on the LIVE database3 of images.

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

    PubMed Central

    2010-01-01

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

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

    PubMed

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

    2014-01-01

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

  2. LASER DOPPLER IMAGING OF FINGER SKIN BLOOD FLOW IN PATIENTS AFTER MICROVASCULAR REPAIR OF THE ULNAR ARTERY AT THE WRIST

    Microsoft Academic Search

    S. BORNMYR; M. ARNER; H. SVENSSON

    1994-01-01

    Laser Doppler imaging is a new, non-invasive technique allowing the spatial distribution and the temporal variation of the skin blood flow to be monitored. A mean blood flow value over an area, such as the finger-tip in the present study, can also be calculated. Recordings from 12 patients with a sutured ulnar artery following trauma did not significantly differ from

  3. Novel method for localization of common carotid artery transverse section in ultrasound images using modified Viola-Jones detector.

    PubMed

    Ríha, Kamil; Mašek, Jan; Burget, Radim; Beneš, Radek; Závodná, Eva

    2013-10-01

    This article describes a novel method for highly accurate and effective localization of the transverse section of the carotis comunis artery in ultrasound images. The method has a high success rate, approximately 97%. Unlike analytical methods based on geometric descriptions of the object sought, the method proposed here can cover a large area of shape variation of the artery under study, which normally occurs during examinations as a result of the pressure on the examined tissue, tilt of the probe, setup of the sonographic device, and other factors. This method shows great promise in automating the process of determining circulatory system parameters in the non-invasive clinical diagnostics of cardiovascular diseases. The method employs a Viola-Jones detector that has been specially adapted for efficient detection of transverse sections of the carotid artery. This algorithm is trained on a set of labeled images using the AdaBoost algorithm, Haar-like features and the Matthews coefficient. The training algorithm of the artery detector was modified using evolutionary algorithms. The method for training a cascade of classifiers achieves on a small number of positive and negative training data samples (about 500 images) a high success rate in a computational time that allows implementation of the detector in real time. Testing was performed on images of different patients for whom different ultrasonic instruments were used under different conditions (settings) so that the algorithm developed is applicable in general radiologic practice. PMID:23849387

  4. Subclinical Cerebral Complications After Coronary Artery Bypass Grafting: Prospective Analysis With Magnetic Resonance Imaging, Quantitative Electroencephalography, and Neuropsychological Assessment

    Microsoft Academic Search

    Ritva Vanninen; Marja Aikia; Mervi Kononen; Kaarina Partanen; Harri Tulla; Paivi Hartikainen; Juhani Partanen; Hannu Manninen; Pentti Enberg; Mikko Hippelainen

    1998-01-01

    Objective: To analyze the frequency and severity of sub- clinical cerebral complications associated with coro- nary artery bypass grafting (CABG). Design: A prospective controlled study using preopera- tive and postoperative magnetic resonance imaging (MRI) of the brain, quantitative electroencephalography (QEEG), and detailed neuropsychological and neurologic exami- nations as potentially sensitive indicators of subclinical cerebral injury associated with CABG.

  5. Multimodality imaging of atherosclerotic plaque activity and composition using FDG-PET\\/CT and MRI in carotid and femoral arteries

    Microsoft Academic Search

    Stephane S. Silvera; Hamza el Aidi; James H. F. Rudd; Venkatesh Mani; Lingde Yang; Michael Farkouh; Valentin Fuster; Zahi A. Fayad

    2009-01-01

    PurposeTo evaluate the relationship between atherosclerotic plaque inflammation, as assessed by FDG-Positron Emission Tomography\\/Computed Tomography (FDG-PET\\/CT), and plaque morphology and composition, as assessed by magnetic resonance imaging (MRI), in the carotid and femoral arteries.

  6. 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.

  7. Quality of life of coronary artery disease patients after the implementation of planning strategies for medication adherence 1

    PubMed Central

    Lourenço, Laura Bacelar de Araujo; Rodrigues, Roberta Cunha Matheus; São-João, Thaís Moreira; Gallani, Maria Cecilia; Cornélio, Marilia Estevam

    2015-01-01

    OBJECTIVE: to compare the general and specific health-related quality of life (HRQoL) between the Intervention (IG) and Control (CG) groups of coronary artery disease patients after the implementation of Action Planning and Coping Planning strategies for medication adherence and to verify the relationship between adherence and HRQoL. METHOD: this was a controlled and randomized study. RESULTS: the sample (n=115) was randomized into two groups, IG (n=59) and CG (n=56). Measures of medication adherence and general and specific HRQoL were obtained in the baseline and after two months of monitoring. CONCLUSION: the findings showed that the combination of intervention strategies - Action Planning and Coping Planning for medication adherence did not affect the HRQoL of coronary artery disease patients in outpatient monitoring. PMID:25806626

  8. 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

    2015-03-01

    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.

  9. Blurriness measurement in frequency domain for image quality assessment

    NASA Astrophysics Data System (ADS)

    Tahir, Qadri Muhammad; Noman, Mehmood S.; Tahir, Aisha

    2011-10-01

    DCT based digital image and video compression leads to visible distortions like blockiness and blurriness, however this paper mainly focuses blurriness artifact. Subjective quality assessments are reliable but they are very costly and can't be computerized. This paper proposes three different objective quality assessment methods for blurriness estimation using full reference, reduced reference and no reference approaches. The distortion is measured in frequency domain by comparing the high frequency coefficients of the coded image. Before blurriness estimation in frequency domain, the property of Human Visual System is implemented by applying the spatial masking in spatial domain. Since the distortion is not likely to be in same amount in every part of the coded image therefore the coded image is divided into blocks and the distortion is calculated locally for each block and accumulated in the end for a single quality metric. The results show that the full and reduced reference meters are more reliable due to the availability of some reference information at receiver end. The work is tested on different set of blurred images from LIVE image database and the Pearson's correlation coefficient of 94.43% is obtained for full reference mode while it is 94.20% and 82.03% for reduced reference and no reference respectively.

  10. 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.

  11. 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.

  12. Coronary artery atherectomy reduces plaque shear strains: an endovascular elastography imaging study.

    PubMed

    Keshavarz-Motamed, Zahra; Saijo, Yoshifumi; Majdouline, Younes; Riou, Laurent; Ohayon, Jacques; Cloutier, Guy

    2014-07-01

    Mechanical response and properties of the arterial wall can be used to identify the biomechanical instability of plaques and predict their vulnerability to rupture. Shear strain elastography (SSE) is proposed to identify vulnerable plaque features attributed to mechanical structural heterogeneities. The aims of this study were: 1) to report on the potential of SSE to identify atherosclerotic plaques; and 2) to use SSE maps to highlight biomechanical changes in lesion characteristics after directional coronary atherectomy (DCA) interventions. For this purpose, SSE was imaged using in vivo intravascular ultrasound (IVUS) radio-frequency data collected from 12 atherosclerotic patients before and after DCA intervention. Coronary atherosclerotic plaques (pre-DCA) showed high SSE magnitudes with large affected areas. There were good correlations between SSE levels and soft plaque content (i.e., cellular fibrosis, thrombosis and fibrin) (mean |SSE| vs. soft plaque content: r = 0.82, p < 0.01). Significant differences were noticed between SSE images before and after DCA. Stable arteries (post-DCA) exhibited lower values than pre-DCA vessels (e.g., pre-DCA: mean |SSE| = 3.9 ± 0.2% vs. 1.1 ± 0.2% post-DCA, p < 0.001). Furthermore, SSE magnitude was statistically higher in plaques with a high level of inflammation (e.g., mean |SSE| had values of 4.8 ± 0.4% in plaques with high inflammation, whereas it was reduced to 1.8 ± 0.2% with no inflammation, p < 0.01). This study demonstrates the potential of the IVUS-based SSE technique to detect vulnerable plaques in vivo. PMID:24835433

  13. Arterial spin labelling at 3-T MR imaging for detection of individuals with Alzheimer’s disease

    Microsoft Academic Search

    Takashi Yoshiura; Akio Hiwatashi; Tomoyuki Noguchi; Koji Yamashita; Yasumasa Ohyagi; Akira Monji; Eiki Nagao; Hironori Kamano; Osamu Togao; Hiroshi Honda

    2009-01-01

    The purpose of this study was to determine whether arterial spin labelling (ASL) at 3-T MR imaging can be used to discriminate\\u000a individuals with Alzheimer’s disease (AD) from cognitively normal subjects. Twenty AD patients and 23 cognitively normal control\\u000a subjects were studied using ASL on a 3-T MR imager. Absolute regional cerebral blood flow (rCBF) maps were calculated. In\\u000a addition,

  14. 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.

  15. Quality assessment for multitemporal and multisensor image fusion

    NASA Astrophysics Data System (ADS)

    Ehlers, Manfred; Klonus, Sascha

    2008-10-01

    Generally, image fusion methods are classified into three levels: pixel level (iconic), feature level (symbolic) and knowledge or decision level. In this paper we focus on iconic techniques for image fusion. There exist a number of established fusion techniques that can be used to merge high spatial resolution panchromatic and lower spatial resolution multispectral images that are simultaneously recorded by one sensor. This is done to create high resolution multispectral image datasets (pansharpening). In most cases, these techniques provide very good results, i.e. they retain the high spatial resolution of the panchromatic image and the spectral information from the multispectral image. These techniques, when applied to multitemporal and/or multisensoral image data, still create spatially enhanced datasets but usually at the expense of the spectral consistency. In this study, a series of nine multitemporal multispectral remote sensing images (seven SPOT scenes and one FORMOSAT scene) is fused with one panchromatic Ikonos image. A number of techniques are employed to analyze the quality of the fusion process. The images are visually and quantitatively evaluated for spectral characteristics preservation and for spatial resolution improvement. Overall, the Ehlers fusion which was developed for spectral characteristics preservation for multi-date and multi-sensor fusion showed the best results. It could not only be proven that the Ehlers fusion is superior to all other tested algorithms but also the only one that guarantees an excellent color preservation for all dates and sensors.

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

    SciTech Connect

    Christensen, James D.; Kirichenko, Alexander; Gayou, Olivier [Department of Radiation Oncology, Allegheny General Hospital, Pittsburgh, Pennsylvania 15212 (United States)] [Department of Radiation Oncology, Allegheny General Hospital, Pittsburgh, Pennsylvania 15212 (United States)

    2013-08-15

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

  17. 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.

  18. 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

  19. Registration Accuracy and Quality of Real-Life Images

    PubMed Central

    Hsu, Wei-Yen

    2012-01-01

    Background A common registration problem for the application of consumer device is to align all the acquired image sequences into a complete scene. Image alignment requires a registration algorithm that will compensate as much as possible for geometric variability among images. However, images captured views from a real scene usually produce different distortions. Some are derived from the optic characteristics of image sensors, and others are caused by the specific scenes and objects. Methodology/Principal Findings An image registration algorithm considering the perspective projection is proposed for the application of consumer devices in this study. It exploits a multiresolution wavelet-based method to extract significant features. An analytic differential approach is then proposed to achieve fast convergence of point matching. Finally, the registration accuracy is further refined to obtain subpixel precision by a feature-based modified Levenberg-Marquardt method. Due to its feature-based and nonlinear characteristic, it converges considerably faster than most other methods. In addition, vignette compensation and color difference adjustment are also performed to further improve the quality of registration results. Conclusions/Significance The performance of the proposed method is evaluated by testing the synthetic and real images acquired by a hand-held digital still camera and in comparison with two registration techniques in terms of the squared sum of intensity differences (SSD) and correlation coefficient (CC). The results indicate that the proposed method is promising in registration accuracy and quality, which are statistically significantly better than other two approaches. PMID:22829876

  20. Functional magnetic resonance imaging of awake monkeys: some approaches for improving imaging quality.

    E-print Network

    Roe, Anna Wang

    quality. Gang Chen1,a, b, c , Feng Wang1,b,c , Barbara C. Dillenburger2,b,c , Robert M. Friedmana , Li M results. We evaluated the influence of two main variables on image quality. First, we show how important

  1. The image quality of the Southern African Large Telescope (SALT)

    Microsoft Academic Search

    Darragh E. O'Donoghue; Eli Atad-Ettedgui; Luis Balona; Bruce C. Bigelow; John A. Booth; Lucian Botha; Janus D. Brink; David A. H. Buckley; Phil Charles; Alrin Christians; J. Christopher Clemens; Lisa A. Crause; Steven M. Crawford; Geoffrey P. Evans; Hitesh Gajjar; Yas Hashimoto; Malcolm Hendricks; Alexei Kniazev; Anthony R. Koeslag; Willie P. Koorts; Herman J. Kriel; Nicola S. Loaring; Jonathan Love; Fred Marang; Douglas Metcalfe; Brennan Meyer; James O'Connor; Charl A. du Plessis; Lawrence W. Ramsey; Encarni Romero-Colmenero; Craig Sass; Johann C. Scholtz; Ramotholo Sefako; Sandisa Siyengo; Martin Still; Ockert J. Strydom; Arkadiusz Swat; Johann F. Du Toit; Petri Vaisanen; Martyn Wells; Hannah Worters

    2008-01-01

    Construction of the Southern African Large Telescope (SALT) was largely completed by the end of 2005 and since then it has been in intensive commissioning. This has now almost been completed except for the telescope's image quality which shows optical aberrations, chiefly a focus gradient across the focal plane, along with astigmatism and other less significant aberrations. This paper describes

  2. Effect of scatter on image quality in synchrotron radiation mammography

    NASA Astrophysics Data System (ADS)

    Moeckli, Raphael; Verdun, Francis R.; Fiedler, Stefan; Pachoud, Marc; Schnyder, Pierre; Valley, Jean-Francois

    2001-06-01

    The display of low-contrast structures and fine microcalcifications is essential for the early diagnosis of breast cancer. In order to achieve a high image quality level with a minimum amount of radiation delivered to the patient, the use of different spectra (Mo or Rh anode and filters) was introduced. The European Synchrotron Radiation Facility is able to produce a monochromatic beam with a high photon flux. It is thus a powerful tool to study the effect of beam energy on image quality and dose in mammography. Our image quality assessment is based on the calculation of the size of the smallest microcalcification detectable on a radiograph, derived from the statistical decision theory. The mean glandular dose is simultaneously measured. Compared with conventional mammography units, the monochromaticity of synchrotron beams improves contrast and the use of a slit instead of an anti-scatter grid leads to a higher primary beam transmission. The relative contribution of these two effects on image quality and dose is discussed.

  3. Biomarker, Imaging and Quality of Life Studies Funding Program

    Cancer.gov

    Funded National Clinical Trials Network (NCTN) and Community Clinical Oncology Program (CCOP) Research Bases are invited to apply for funding to support biomarker, imaging, and quality of life studies with or without Cost-Effectiveness Analysis (CEA) proposals which are associated with NCI clinical trial concepts.

  4. Analyzing the Quality of Supernovae Search Image Subtraction James Snitzer

    E-print Network

    Cinabro, David

    Analyzing the Quality of Supernovae Search Image Subtraction James Snitzer Adviser: John Marriner the properties of dark energy. One way DES does this is through the observation of type 1a supernovae on the luminosity observed on earth, scientists can find how far away the supernova must be. The light spectrum

  5. Optoelectronic complex inner product for evaluating quality of image segmentation

    NASA Astrophysics Data System (ADS)

    Power, Gregory J.; Awwal, Abdul Ahad S.

    2000-11-01

    In automatic target recognition and machine vision applications, segmentation of the images is a key step. Poor segmentation reduces the recognition performance. For some imaging systems such as MRI and Synthetic Aperture Radar (SAR) it is difficult even for humans to agree on the location of the edge which allows for segmentation. A real- time dynamic approach to determine the quality of segmentation can enable vision systems to refocus of apply appropriate algorithms to ensure high quality segmentation for recognition. A recent approach to evaluate the quality of image segmentation uses percent-pixels-different (PPD). For some cases, PPD provides a reasonable quality evaluation, but it has a weakness in providing a measure for how well the shape of the segmentation matches the true shape. This paper introduces the complex inner product approach for providing a goodness measure for evaluating the segmentation quality based on shape. The complex inner product approach is demonstrated on SAR target chips obtained from the Moving and Stationary Target Acquisition and Recognition (MSTAR) program sponsored by the Defense Advanced Research Projects Agency (DARPA) and the Air Force Research Laboratory (AFRL). The results are compared to the PPD approach. A design for an optoelectronic implementation of the complex inner product for dynamic segmentation evaluation is introduced.

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

    E-print Network

    Wahle, Andreas

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

  7. Multimodality imaging in bland-White-Garland syndrome in an adult with a left dominant coronary artery system.

    PubMed

    Ripley, David P; Gosling, Oliver E; Harries, Simon; Spurrell, Philip A; Bellenger, Nick G

    2014-01-01

    Bland-White-Garland syndrome, also known as anomalous origin of the left coronary artery from the pulmonary artery, is a rare congenital disorder affecting around one in 300,000 live births. The majority of these present within the first year of life with 90% mortality rate if untreated and consequently is an extremely rare presentation in the adult. We present the first published case with a left dominant system in an adult presenting in their late 20s, illustrated by multimodality imaging. PMID:23701826

  8. 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.

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

    PubMed

    Liu, Bilan; Zhu, Tong; Zhong, Jianhui

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  11. Structural similarity analysis for brain MR image quality assessment

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  12. 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.

  13. Assessment of Decline in Health-Related Quality of Life among Angina-Free Patients Undergoing Coronary Artery Bypass Graft Surgery

    Microsoft Academic Search

    Paul A. Pirraglia; Janey C. Peterson; Pamela Williams-Russo; Mary E. Charlson

    2003-01-01

    Purpose: Coronary artery bypass graft (CABG) surgery generally decreases symptoms and improves quality of life, but for those patients without angina, prolongation of life takes precedence. We used the SF-36 to assess changes in health-related quality of life (HRQOL) among patients who were angina free prior to CABG compared to those reporting angina. Methods: We combined data from two randomized

  14. 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

  15. 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

  16. Image quality issues in a static image-based telepathology consultation practice

    Microsoft Academic Search

    Bruce H Williams; In Soon Hong; Florabel G Mullick; Daniel R Butler; Roderick F Herring; Timothy J O’Leary

    2003-01-01

    Field selection and image quality have often been identified as impediments in the successful employment of static-image telepathology. One thousand seven hundred fifty-three electronic consultations using static images were performed at the Department of Telemedicine, Armed Forces Institute of Pathology (AFIP) between November 1994 and September 2001, with 98.3% receiving a telepathology diagnosis. In 47.9% of cases, imagery was considered

  17. Advanced multimodality imaging of an anomalous vessel between the ascending aorta and main pulmonary artery in a dog

    PubMed Central

    Markovic, Lauren E.; Kellihan, Heidi B.; Roldán-Alzate, Alejandro; Drees, Randi; Bjorling, Dale E.; Francois, Chris J.

    2014-01-01

    A 1-year-old male German shorthaired pointer was referred for evaluation of tachypnea and hemoptysis. A grade VI/VI left basilar continuous murmur was ausculted. Multimodality imaging consisting of thoracic radiographs, transthoracic and transesophageal echocardiography, fluoroscopy-guided selective angiography, computed tomography angiogram (CTA) and magnetic resonance angiogram (MRA), was performed on this patient. The defect included a left-to-right shunting anomalous vessel between the ascending aorta and main pulmonary artery, along with a dissecting aneurysm of the main and right pulmonary artery. An MRA postprocessing technique (PC-VIPR) was used to allow for high resolution angiographic images and further assessment of the patient’s hemodynamics prior to surgical correction. This case report describes the clinical course of a canine patient with a rare form of congenital cardiac disease, and the multiple imaging modalities that were used to aid in diagnosis and treatment. PMID:24485987

  18. 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

  19. Advanced multimodality imaging of an anomalous vessel between the ascending aorta and main pulmonary artery in a dog.

    PubMed

    Markovic, Lauren E; Kellihan, Heidi B; Roldán-Alzate, Alejandro; Drees, Randi; Bjorling, Dale E; Francois, Chris J

    2014-03-01

    A 1-year-old male German shorthaired pointer was referred for evaluation of tachypnea and hemoptysis. A grade VI/VI left basilar continuous murmur was ausculted. Multimodality imaging consisting of thoracic radiographs, transthoracic and transesophageal echocardiography, fluoroscopy-guided selective angiography, computed tomography angiogram (CTA) and magnetic resonance angiogram (MRA), was performed on this patient. The defect included a left-to-right shunting anomalous vessel between the ascending aorta and main pulmonary artery, along with a dissecting aneurysm of the main and right pulmonary artery. An MRA post-processing technique (PC VIPR) was used to allow for high resolution angiographic images and further assessment of the patient's hemodynamics prior to surgical correction. This case report describes the clinical course of a canine patient with a rare form of congenital cardiac disease, and the multiple imaging modalities that were used to aid in diagnosis and treatment. PMID:24485987

  20. Effect of Gadolinium on Phase-Contrast MRAngiography of the Renal Arteries

    Microsoft Academic Search

    James C. Bass; Martin R. Prince; Frank J. Londy; Thomas L. Chenevert

    OBJECTIVE. Our aim was to evaluate the effect of gadolinium chelates on image quality in phase-contrast MR angiography of renal arteries in patients suspected of having renal artery stenosis. MATERIALS AND METHODS. In 24 patients, axial three-dimensional phase-contrast MR angiography of the renal arteries was obtained on a l.5-T MR imaging system before and after administration of gadolinium contrast agent.

  1. 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.

  2. Arterial calcifications

    PubMed Central

    Rennenberg, Roger J M W; Schurgers, Leon J; Kroon, Abraham A; Stehouwer, Coen D A

    2010-01-01

    Abstract Arterial calcifications as found with various imaging techniques, like plain X-ray, computed tomography or ultrasound are associated with increased cardiovascular risk. The prevalence of arterial calcification increases with age and is stimulated by several common cardiovascular risk factors. In this review, the clinical importance of arterial calcification and the currently known proteins involved are discussed. Arterial calcification is the result of a complex interplay between stimulating (bone morphogenetic protein type 2 [BMP-2], RANKL) and inhibitory (matrix Gla protein, BMP-7, osteoprotegerin, fetuin-A, osteopontin) proteins. Vascular calcification is especially prevalent and related to adverse outcome in patients with renal insufficiency and diabetes mellitus. We address the special circumstances and mechanisms in these patient groups. Treatment and prevention of arterial calcification is possible by the use of specific drugs. However, it remains to be proven that reduction of vascular calcification in itself leads to a reduced cardiovascular risk. PMID:20716128

  3. SPOT5: first in-flight radiometric image quality results

    NASA Astrophysics Data System (ADS)

    Pascal, Veronique; Lebegue, Laurent; Meygret, Aime; Laubies, Marie-Christine; Hourcastagnou, Jean-Noel; Hillairet, Emmanuel

    2003-04-01

    The SPOT5 remote sensing satellite was launched in May 2002. It provides SPOT service continuity above and beyond SPOT4 operation but the SPOT5 system also significantly improves the SPOT service with the new characteristics of its two HRG (High Resolution Geometry) cameras and its HRS (High Resolution Stereo) camera. SPOT5's first two months of life in orbit were dedicated to instrument calibration and the assessment of image quality performances. During this period, the CNES team used specific target programming to compute image correction parameters and estimate the performance of the image processing chain, at system level. This paper focuses on the relative radiometric performances of the different spectral bands for the three instruments, deduced from in-flight measurements. For each spectral band, a radiometric model gives the ratio between detector response and input radiance. This model takes the architecture of the onboard image chain into account. Calibration provides the normalisation parameters (dark currents and relative inter-detector sensitivities) used to correct the images. The quality of the corrected images is quantified through several signal-to-noise ratio measurements based on different techniques. These methods are presented and their accuracy is discussed. Finally, a comparison is given between flight measurements and ground measurements.

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

    SciTech Connect

    Walker, Woodruff J. [Royal Surrey County Hospital, Department of Radiology (United Kingdom); Bratby, Mark John [St George's Hospital, Department of Radiology (United Kingdom)], E-mail: markbratby@doctors.org.uk

    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.

  5. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  7. Image quality assessment based on multiscale geometric analysis.

    PubMed

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

    2009-07-01

    Reduced-reference (RR) image quality assessment (IQA) has been recognized as an effective and efficient way to predict the visual quality of distorted images. The current standard is the wavelet-domain natural image statistics model (WNISM), which applies the Kullback-Leibler divergence between the marginal distributions of wavelet coefficients of the reference and distorted images to measure the image distortion. However, WNISM fails to consider the statistical correlations of wavelet coefficients in different subbands and the visual response characteristics of the mammalian cortical simple cells. In addition, wavelet transforms are optimal greedy approximations to extract singularity structures, so they fail to explicitly extract the image geometric information, e.g., lines and curves. Finally, wavelet coefficients are dense for smooth image edge contours. In this paper, to target the aforementioned problems in IQA, we develop a novel framework for IQA to mimic the human visual system (HVS) by incorporating the merits from multiscale geometric analysis (MGA), contrast sensitivity function (CSF), and the Weber's law of just noticeable difference (JND). In the proposed framework, MGA is utilized to decompose images and then extract features to mimic the multichannel structure of HVS. Additionally, MGA offers a series of transforms including wavelet, curvelet, bandelet, contourlet, wavelet-based contourlet transform (WBCT), and hybrid wavelets and directional filter banks (HWD), and different transforms capture different types of image geometric information. CSF is applied to weight coefficients obtained by MGA to simulate the appearance of images to observers by taking into account many of the nonlinearities inherent in HVS. JND is finally introduced to produce a noticeable variation in sensory experience. Thorough empirical studies are carried out upon the LIVE database against subjective mean opinion score (MOS) and demonstrate that 1) the proposed framework has good consistency with subjective perception values and the objective assessment results can well reflect the visual quality of images, 2) different transforms in MGA under the new framework perform better than the standard WNISM and some of them even perform better than the standard full-reference IQA model, i.e., the mean structural similarity index, and 3) HWD performs best among all transforms in MGA under the framework. PMID:19447715

  8. 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.

  9. 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.

  10. 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).

  11. Reduced reference image quality assessment via sub-image similarity based redundancy measurement

    NASA Astrophysics Data System (ADS)

    Mou, Xuanqin; Xue, Wufeng; Zhang, Lei

    2012-03-01

    The reduced reference (RR) image quality assessment (IQA) has been attracting much attention from researchers for its loyalty to human perception and flexibility in practice. A promising RR metric should be able to predict the perceptual quality of an image accurately while using as few features as possible. In this paper, a novel RR metric is presented, whose novelty lies in two aspects. Firstly, it measures the image redundancy by calculating the so-called Sub-image Similarity (SIS), and the image quality is measured by comparing the SIS between the reference image and the test image. Secondly, the SIS is computed by the ratios of NSE (Non-shift Edge) between pairs of sub-images. Experiments on two IQA databases (i.e. LIVE and CSIQ databases) show that by using only 6 features, the proposed metric can work very well with high correlations between the subjective and objective scores. In particular, it works consistently well across all the distortion types.

  12. Flurpiridaz F 18 PET: Phase II Safety and Clinical Comparison with SPECT Myocardial Perfusion Imaging for Detection of Coronary Artery Disease

    PubMed Central

    Berman, Daniel S.; Maddahi, Jamshid; Tamarappoo, B. K.; Czernin, Johannes; Taillefer, Raymond; Udelson, James E.; Gibson, C. Michael; Devine, Marybeth; Lazewatsky, Joel; Bhat, Gajanan; Washburn, Dana

    2015-01-01

    Objectives Phase II trial to assess flurpiridaz F 18 for safety and compare its diagnostic performance for PET myocardial perfusion imaging (MPI) to Tc-99m SPECT-MPI regarding image quality, interpretative certainty, defect magnitude and detection of coronary artery disease (CAD)(? 50% stenosis) on invasive coronary angiography (ICA). Background In preclinical and phase I studies, flurpiridaz F 18 has shown characteristics of an essentially ideal MPI tracer. Methods 143 patients from 21 centers underwent rest-stress PET and Tc-99m SPECT-MPI. Eighty-six patients underwent ICA, and 39 had low-likelihood of CAD. Images were scored by 3 independent, blinded readers. Results A higher % of images were rated as excellent/good on PET vs. SPECT on stress (99.2% vs. 88.5%, p<0.01) and rest (96.9% vs. 66.4, p<0.01) images. Diagnostic certainty of interpretation (% cases with definitely abnormal/normal interpretation) was higher for PET vs. SPECT (90.8% vs. 70.9%, p<0.01). In 86 patients who underwent ICA, sensitivity of PET was higher than SPECT [78.8% vs. 61.5%, respectively (p=0.02)]. Specificity was not significantly different (PET:76.5% vs. SPECT:73.5%). Receiver operating characteristic curve area was 0.82±0.05 for PET and 0.70±0.06 for SPECT (p=0.04). Normalcy rate was 89.7% with PET and 97.4% with SPECT (p=NS). In patients with CAD on ICA, the magnitude of reversible defects was greater with PET than SPECT (p=0.008). Extensive safety assessment revealed that flurpiridaz F 18 was safe in this cohort. Conclusions In this Phase 2 trial, PET MPI using flurpiridaz F 18 was safe and superior to SPECT MPI for image quality, interpretative certainty, and overall CAD diagnosis. PMID:23265345

  13. Evaluation of Extrahepatic Perfusion of Anticancer Drugs in the Right Gastric Arterial Region on Fused Images Using Combined CT\\/SPECT: Is Extrahepatic Perfusion Predictive of Gastric Toxicity?

    Microsoft Academic Search

    Osamu Ikeda; Yoshitaka Tamura; Yutaka Nakasone; Shinya Shiraishi; Kouichi Kawanaka; Seiji Tomiguchi; Shouji Morishita; Hiroshi Takamori; Akira Chikamoto; Keiichirou Kanemitsu; Yasuyuki Yamashita

    2007-01-01

    Background. Hepatic arterial infusion (HAI) chemotherapy is effective for treating primary and metastatic carcinomas of the liver. Since hepatic arteries also supply the stomach and duodenum, HAI may result in unwanted infusion into the upper gastrointestinal tract and consequent gastric toxicity. Using fused images obtained with a combined SPECT\\/CT system, we assessed extrahepatic perfusion (EHP) and its correlation with gastrointestinal

  14. 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

  15. 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.

  16. 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

  17. Radiation dose in cardiac CT angiography: protocols and image quality.

    PubMed

    Oliveira, L C G; Gottlieb, I; Rizzi, P; Lopes, R T; Kodlulovich, S

    2013-06-01

    This paper aims to evaluate the radiation dose exposure of patients submitted to cardiac computed tomography angiography. The effective dose was obtained from the product of dose-length product values and the conversion factor established in the European Working Group for Guidelines on Quality Criteria in CT. The image noise and contrast- and signal-to-noise ratios were obtained for all images. Sixty-four- and 256-slice CT angiographies were used in 211 (68.5 %) and 97 (31.5 %) patients, respectively. The calculated mean effective dose with prospective CT angiography was 6.0±1.0 mSv and the retrospective mode was 8.4±1.2 mSv. The mean image noise values were 38.5±9.5 and 21.4 ± 5.3 for prospective and retrospective modes, respectively. It was observed that the image noise increased by 44.4 % using a prospective mode. Prospective CT angiography reduces radiation dose by ?29 % compared with the retrospective mode, while maintaining diagnostic image quality and the ability to assess obstructions in patients. PMID:23235799

  18. Effect of monitor image quality on the soft-copy interpretation of chest CR images

    NASA Astrophysics Data System (ADS)

    Siegel, Eliot L.; Reiner, Bruce I.; Hooper, Frank; Sevarance, Steven; Brower, Steven

    2001-08-01

    Four radiologists independently reviewed eighty individual thoracic computed radiography images. These consisted of 41 normal radiographs and 39 abnormal radiographs. Images were reviewed using 2,048 by 1,536 pixel monitors which varied widely in image quality as documented using a SMPTE pattern. Overall sensitivity for pathology ranged from .94 to .97 for the radiologists and varied minimally (0.95 to 1.0) for the four monitor quality levels tested while specificity varied to a much greater extent for the radiologists (0.68 to 0.93) and for the various monitors (0.76 to 0.93). The control (good quality) monitor demonstrated substantially higher specificity than the other three monitors (which varied from very poor to fair) but there were no significant differences among the non-control monitors despite their wide variance with regard to image quality. There was no significant difference in sensitivity for the monitors (including the control). Additionally no significant differences were found in the level of diagnostic confidence by the radiologists for the four monitors. These findings suggest that the actual effect of monitor quality degradation on clinical accuracy and confidence is complex and correlates poorly with traditional quality assurance metrics performed for these systems. Additional investigation into the monitor characteristics which most affect clinical confidence and performance is warranted.

  19. 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. [Radiation Medicine Program, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada); Radiation Medicine Program, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada) and Department of Radiation Oncology, University of Toronto, Toronto, Ontario M5S 1A1 (Canada); Radiation Medicine Program, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5 2M9 (Canada); Radiation Medicine Program, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada) and Ontario Cancer Institute, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada); Ontario Cancer Institute, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada); Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5S 1A1 (Canada) and Department of Radiation Oncology, University of Toronto, Toronto, Ontario M5S 1A1 (Canada); Radiation Medicine Program, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada); Ontario Cancer Institute, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada); Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5S 1A1 (Canada) and Department of Radiation Oncology, University of Toronto, Toronto, Ontario M5S 1A1 (Canada)

    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.

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

    PubMed Central

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

    2011-01-01

    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 (R2?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?1, respectively. Targeting accuracy by means of film irradiations was shown to have a mean displacement error of [?x,?y,?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. PMID:21452722

  1. Impact of hypertension on the accuracy of exercise stress myocardial perfusion imaging for the diagnosis of coronary artery disease

    PubMed Central

    Elhendy, A; van Domburg, R T; Sozzi, F; Poldermans, D; Bax, J; Roelandt, J

    2001-01-01

    AIM—To compare the accuracy of exercise stress myocardial perfusion single photon emission computed tomography (SPECT) imaging for the diagnosis of coronary artery disease in patients with and without hypertension.?METHODS—A symptom limited bicycle exercise stress test in conjunction with 99m technetium sestamibi or tetrofosmin SPECT imaging was performed in 332 patients (mean (SD) age, 57 (10) years; 257 men, 75 women) without previous myocardial infarction who underwent coronary angiography. Of these, 137 (41%) had hypertension. Rest SPECT images were acquired 24 hours after the stress test. An abnormal scan was defined as one with reversible or fixed perfusion defects.?RESULTS—In hypertensive patients, myocardial perfusion abnormalities were detected in 79 of 102 patients with significant coronary artery disease and in nine of 35 patients without. In normotensive patients, myocardial perfusion abnormalities were detected in 104 of 138 patients with significant coronary artery disease and in 16 of 57 patients without. There were no differences between normotensive and hypertensive patients in sensitivity (77% (95% confidence interval (CI) 69% to 86%) v 75% (95% CI 68% to 83%)), specificity (74% (95% CI 60% to 89%) v 72% (95% CI 60% to 84%)), and accuracy (77% (95% CI 70% to 84%) v 74% (95% CI 68% to 80%)) of exercise SPECT for diagnosing coronary artery disease. The accuracy of SPECT was greater than electrocardiography, both in hypertensive patients (p = 0.005) and in normotensive patients (p = 0.0001). For the detection of coronary artery disease in individual vessels, sensitivity was 58% (95% CI 51% to 65%) v 57% (95% CI 51% to 64%), specificity was 86% (95% CI 82% to 90%) v 85% (95% CI 81% to 89%), and accuracy was 74% (95% CI 70% to 78%) v 74% (95% CI 70% to 78%) in patients with and without hypertension (NS).?CONCLUSIONS—In the usual clinical setting, the value of exercise myocardial perfusion scintigraphy for diagnosing coronary artery disease is not degraded by the presence of hypertension.???Keywords: hypertension; coronary artery disease; exercise stress test; myocardial perfusion PMID:11359747

  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. 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.

  5. Advanced imaging in colonoscopy and its impact on quality.

    PubMed

    Sharma, Prateek; Gupta, Neil; Kuipers, Ernst J; Repici, Alessandro; Wallace, Michael

    2014-01-01

    Detecting and resecting colonic polyps during endoscopy has been shown to reduce CRC. At the same time, endoscopy has faced substantial technical improvements and continues to undergo major changes. Detection of colorectal neoplasias is facilitated by using high-definition endoscopy, and characterization of lesions is more accurate by using virtual CE. High-definition endoscopy has found widespread use, whereas virtual CE is still more often used in tertiary centers and for high-risk patient groups. Endomicroscopy has opened the door for in vivo histology and functional as well as molecular imaging. Thorough training of the endoscopists is necessary, and redefined reimbursement codes may help make these techniques available in the clinical arena for high-risk patients who are most probable to benefit from the more advanced diagnostic endoscopy techniques. Over recent years, there has also been an increasing push by healthcare payors and providers to improve the quality of healthcare services. The ultimate goal of monitoring quality measures is to improve the overall health of the population and, for colon cancer screening, to reduce the incidence and mortality of colon cancer. However, the development of an appropriate quality measure and ensuring the accuracy of the data on which we base our efforts are among the first challenges that we must meet (Table 1). The continued technologic advancements in colonoscopy and endoscopic imaging may result in improvements in the quality of colonoscopy and should lead to a decrease in the incidence and mortality from colon cancer. PMID:24119713

  6. An automatic graph-based approach for artery/vein classification in retinal images.

    PubMed

    Dashtbozorg, Behdad; Mendonça, Ana Maria; Campilho, Aurélio

    2014-03-01

    The classification of retinal vessels into artery/vein (A/V) is an important phase for automating the detection of vascular changes, and for the calculation of characteristic signs associated with several systemic diseases such as diabetes, hypertension, and other cardiovascular conditions. This paper presents an automatic approach for A/V classification based on the analysis of a graph extracted from the retinal vasculature. The proposed method classifies the entire vascular tree deciding on the type of each intersection point (graph nodes) and assigning one of two labels to each vessel segment (graph links). Final classification of a vessel segment as A/V is performed through the combination of the graph-based labeling results with a set of intensity features. The results of this proposed method are compared with manual labeling for three public databases. Accuracy values of 88.3%, 87.4%, and 89.8% are obtained for the images of the INSPIRE-AVR, DRIVE, and VICAVR databases, respectively. These results demonstrate that our method outperforms recent approaches for A/V classification. PMID:23693131

  7. 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.

  8. Dynamic contrast–enhanced magnetic resonance imaging in patients with pulmonary arterial hypertension

    PubMed Central

    Condliffe, Robin; Marshall, Helen; Elliot, Charlie; Kiely, David G.; Wild, Jim M.

    2014-01-01

    Abstract 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

  9. 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

  10. 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.

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

    SciTech Connect

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

    1986-01-01

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

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

    PubMed

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

    2006-12-01

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

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

    PubMed Central

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

    2008-01-01

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

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

    PubMed Central

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

    2015-01-01

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

  15. Assessment of human instantaneous arterial diameter using B-mode ultrasound imaging and artificial neural networks: Determination of wall mechanical properties.

    PubMed

    Pessana, F; Venialgo, E; Rubstein, J; Furfaro, A

    2010-01-01

    Wall artery viscoelastic properties (WAVP) are correlated with structural and functional state of the arterial system. An accurate estimation of these properties is achieved measuring wall instantaneous diameter and pressure signals. The aim of this work was to evaluate a new non invasive estimation method of the instantaneous arterial diameter (D), and consequently, WAVP. Ten common carotid arteries of hypertensive men were evaluated. D was calculated by using B-mode ultrasonic imaging and specialized software designed with Artificial Neural Networks. Instantaneous arterial pressure of all subjects was measured by piezoelectric tonometry. Arterial wall properties were evaluated using a linear autoregressive with exogenous input model. The new method, which determinates the arterial diameter, was compared respect to a specialized and previously validated method. Results showed no significant differences in all parameters derived of D (Bland & Altman test) and no differences in all the wall arterial mechanic indexes (p>0.05). For these reasons, the developed software based on Artificial Neural Networks was successful in determining the parameters associated with arterial diameters and it opens up the possibility of real time calculations of arterial wall mechanical properties because of its simplicity. PMID:21096344

  16. 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

  17. Completely blind image quality assessment based on gray-scale fluctuations

    NASA Astrophysics Data System (ADS)

    Yang, Xichen; Sun, Quansen; Wang, Tianshu

    2014-04-01

    Completely blind image quality assessment is the further development of no reference image quality assessment. And this kind quality assessment method is highly unsupervised, training free, and don't rely on natural scene statistic model. This paper proposes a completely blind quality assessment method based on gray-scale fluctuations (GFQA). The new method uses a specific image primitive to analyze the image gray fluctuations. And the analysis result is used to assess the image quality and give the image quality assessment result directly. The experimental results show that the new method accords closely with human subjective judgments of diverse distorted images when tested on the large publicly available `LIVE' Image Quality database.

  18. Dual-Source CT Imaging to Plan Transcatheter Aortic Valve Replacement: Accuracy for Diagnosis of Obstructive Coronary Artery Disease.

    PubMed

    Harris, Brett S; De Cecco, Carlo N; Schoepf, U Joseph; Steinberg, Daniel H; Bayer, Richard R; Krazinski, Aleksander W; Dyer, Kevin T; Sandhu, Monique K; Zile, Michael R; Meinel, Felix G

    2015-04-01

    Purpose To assess the accuracy of computed tomographic (CT) examinations performed for the purpose of transcatheter aortic valve replacement (TAVR) planning to diagnose obstructive coronary artery disease (CAD). Materials and Methods With institutional review board approval, waivers of informed consent, and in compliance with HIPAA, 100 consecutive TAVR candidates (61 men, mean age 79.6 years ± 9.9) who underwent both TAVR planning CT (with a dual-source CT system) and coronary catheter (CC) angiographic imaging were retrospectively analyzed. At both modalities, the presence of stenosis in the native coronary arteries was assessed. Additionally, all coronary bypass grafts were rated as patent or occluded. With CC angiographic imaging as the reference standard, the accuracy of CT for lesion detection on a per-vessel and per-patient basis was calculated. The accuracy of CT for the assessment of graft patency was also analyzed. Results For per-vessel and per-patient analysis for the detection of stenosis that was 50% or more in the native coronary arteries, CT imaging had, respectively, 94.4% and 98.6% sensitivity, 68.4% and 55.6% specificity, 94.7% and 93.8% negative predictive value (NPV), and 67.0% and 85.7% positive predictive value. Per-patient sensitivity of stenosis 50% or greater with CT for greater than 70% stenosis at CC angiographic imaging was 100%. All 12 vessels in which percutaneous coronary intervention was performed were correctly identified as demonstrating stenosis 50% or greater with CT. There was agreement between CT and CC angiographic imaging regarding graft patency in 114 of 115 grafts identified with CC angiographic imaging. Conclusion TAVR planning CT has high sensitivity and NPV in excluding obstructive CAD. An additional preprocedural CC angiographic examination may not be required in TAVR candidates with a CT examination that does not show obstructive CAD. PMID:25393848

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

    PubMed Central

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

    2013-01-01

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

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

    SciTech Connect

    Flohr, Thomas G.; Leng Shuai; Yu Lifeng; Allmendinger, Thomas; Bruder, Herbert; Petersilka, Martin; Eusemann, Christian D.; Stierstorfer, Karl; Schmidt, Bernhard; McCollough, Cynthia H. [Siemens Healthcare, Computed Tomography, 91301 Forchheim, Germany and Department of Diagnostic Radiology, Eberhard-Karls-Universitaet, 72076 Tuebingen (Germany); Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905 (United States); Siemens Healthcare, Computed Tomography, 91301 Forchheim (Germany); Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905 (United States)

    2009-12-15

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

  1. Readout-Segmented Echo-Planar Imaging in Diffusion-Weighted MR Imaging in Breast Cancer: Comparison with Single-Shot Echo-Planar Imaging in Image Quality

    PubMed Central

    Kim, Yun Ju; Kang, Bong Joo; Park, Chang Suk; Kim, Hyeon Sook; Son, Yo Han; Porter, David Andrew; Song, Byung Joo

    2014-01-01

    Objective The purpose of this study was to compare the image quality of standard single-shot echo-planar imaging (ss-EPI) and that of readout-segmented EPI (rs-EPI) in patients with breast cancer. Materials and Methods Seventy-one patients with 74 breast cancers underwent both ss-EPI and rs-EPI. For qualitative comparison of image quality, three readers independently assessed the two sets of diffusion-weighted (DW) images. To evaluate geometric distortion, a comparison was made between lesion lengths derived from contrast enhanced MR (CE-MR) images and those obtained from the corresponding DW images. For assessment of image parameters, signal-to-noise ratio (SNR), lesion contrast, and contrast-to-noise ratio (CNR) were calculated. Results The rs-EPI was superior to ss-EPI in most criteria regarding the qualitative image quality. Anatomical structure distinction, delineation of the lesion, ghosting artifact, and overall image quality were significantly better in rs-EPI. Regarding the geometric distortion, lesion length on ss-EPI was significantly different from that of CE-MR, whereas there were no significant differences between CE-MR and rs-EPI. The rs-EPI was superior to ss-EPI in SNR and CNR. Conclusion Readout-segmented EPI is superior to ss-EPI in the aspect of image quality in DW MR imaging of the breast. PMID:25053898

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

    PubMed

    Yang, Na; Demirkol, Ilker; Heinzelman, Wendi

    2012-01-01

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

  3. Comparing distances for quality assessment of fused images C. Thomas & L. Wald

    E-print Network

    Paris-Sud XI, Université de

    Comparing distances for quality assessment of fused images C. Thomas & L. Wald Ecole des Mines de, image fusion, distances, quality budget ABSTRACT: This communication deals with the fusion of panchromatic (PAN) images of high spatial resolution and multispectral (MS) images of lower resolution in order

  4. An investigation of flat panel equipment variables on image quality with a dedicated cardiac phantom

    NASA Astrophysics Data System (ADS)

    Dragusin, O.; Bosmans, H.; Pappas, C.; Desmet, W.

    2008-09-01

    Image quality (IQ) evaluation plays a key role in the process of optimization of new x-ray systems. Ideally, this process should be supported by real clinical images, but ethical issues and differences in anatomy and pathology of patients make it impossible. Phantom studies might overcome these issues. This paper presents the IQ evaluation of 30 cineangiographic films acquired with a cardiac flat panel system. The phantom used simulates the anatomy of the heart and allows the circulation of contrast agent boluses through coronary arteries. Variables investigated with influence on IQ and radiation dose are: tube potential, detector dose, added Copper filters, dynamic density optimization (DDO) and viewing angle. The IQ evaluation consisted of scoring 4 simulated calcified lesions located on different coronary artery segments in terms of degree of visualization. Eight cardiologists rated the lesions using a five-point scale ((1) lesion not visible to (5) very good visibility). Radiation doses associated to the angiograms are expressed in terms of incident air kerma (IAK) and effective dose that has been calculated with PCXMX software (STUK, Finland) from the exposure settings assuming a standard sized patient of 70 Kg. Mean IQ scores ranged from 1.68 to 4.88. The highest IQ scores were obtained for the angiograms acquired with tube potential 80 kVp, no added Cu filters, DDO 60%, RAO and LAO views and the highest entrance detector dose that has been used in the present study, namely 0.17 ?Gy/im. Radiation doses (IAK ~40 mGy and effective dose of 1 mSv) were estimated for angiograms acquired at 15 frames s-1, detector field-of-view 20 cm, and a length of 5 s. The following parameters improved the IQ factor significantly: a change in tube potential from 96 to 80 kVp, detector dose from 0.10 ?Gy/im to 0.17 ?Gy/im, the absence of Copper filtration. DDO variable which is a post-processing parameter should be carefully evaluated because it alters the quality of the images independently of radiation exposure settings. The SAM anthropomorphic phantom has the advantage of visualization of stenotic lesions during the injection of a contrast agent and using an anatomical background. In the future, this phantom could potentially bridge the gap between physics tests and the clinical reality in the catheterization laboratory.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  6. Color image quality in projection displays: a case study

    NASA Astrophysics Data System (ADS)

    Strand, Monica; Hardeberg, Jon Y.; Nussbaum, Peter

    2005-01-01

    Recently the use of projection displays has increased dramatically in different applications such as digital cinema, home theatre, and business and educational presentations. Even if the color image quality of these devices has improved significantly over the years, it is still a common situation for users of projection displays that the projected colors differ significantly from the intended ones. This study presented in this paper attempts to analyze the color image quality of a large set of projection display devices, particularly investigating the variations in color reproduction. As a case study, a set of 14 projectors (LCD and DLP technology) at Gjovik University College have been tested under four different conditions: dark and light room, with and without using an ICC-profile. To find out more about the importance of the illumination conditions in a room, and the degree of improvement when using an ICC-profile, the results from the measurements was processed and analyzed. Eye-One Beamer from GretagMacbeth was used to make the profiles. The color image quality was evaluated both visually and by color difference calculations. The results from the analysis indicated large visual and colorimetric differences between the projectors. Our DLP projectors have generally smaller color gamut than LCD projectors. The color gamuts of older projectors are significantly smaller than that of newer ones. The amount of ambient light reaching the screen is of great importance for the visual impression. If too much reflections and other ambient light reaches the screen, the projected image gets pale and has low contrast. When using a profile, the differences in colors between the projectors gets smaller and the colors appears more correct. For one device, the average ?E*ab color difference when compared to a relative white reference was reduced from 22 to 11, for another from 13 to 6. Blue colors have the largest variations among the projection displays and makes them therefore harder to predict.

  7. Color image quality in projection displays: a case study

    NASA Astrophysics Data System (ADS)

    Strand, Monica; Hardeberg, Jon Y.; Nussbaum, Peter

    2004-10-01

    Recently the use of projection displays has increased dramatically in different applications such as digital cinema, home theatre, and business and educational presentations. Even if the color image quality of these devices has improved significantly over the years, it is still a common situation for users of projection displays that the projected colors differ significantly from the intended ones. This study presented in this paper attempts to analyze the color image quality of a large set of projection display devices, particularly investigating the variations in color reproduction. As a case study, a set of 14 projectors (LCD and DLP technology) at Gjøvik University College have been tested under four different conditions: dark and light room, with and without using an ICC-profile. To find out more about the importance of the illumination conditions in a room, and the degree of improvement when using an ICC-profile, the results from the measurements was processed and analyzed. Eye-One Beamer from GretagMacbeth was used to make the profiles. The color image quality was evaluated both visually and by color difference calculations. The results from the analysis indicated large visual and colorimetric differences between the projectors. Our DLP projectors have generally smaller color gamut than LCD projectors. The color gamuts of older projectors are significantly smaller than that of newer ones. The amount of ambient light reaching the screen is of great importance for the visual impression. If too much reflections and other ambient light reaches the screen, the projected image gets pale and has low contrast. When using a profile, the differences in colors between the projectors gets smaller and the colors appears more correct. For one device, the average ?E*ab color difference when compared to a relative white reference was reduced from 22 to 11, for another from 13 to 6. Blue colors have the largest variations among the projection displays and makes them therefore harder to predict.

  8. Image Quality Degradation and Retrieval Errors Introduced by Registration and Interpolation of Multispectral Digital Images

    E-print Network

    Theiler, James

    such as boundaries between materials or terrains. For certain applications, sub­pixel accuracy is desired when performed at sub­pixel accuracy requires interpolation, which degrades resolution and image quality brought about by fractional pixel shifting and calculate errors in retrieved quantities (surface

  9. 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.

  10. Comparison of coronary risk factors and quality of life in coronary artery disease patients with versus without diabetes mellitus.

    PubMed

    Pischke, Claudia R; Weidner, Gerdi; Elliott-Eller, Melanie; Scherwitz, Larry; Merritt-Worden, Terri A; Marlin, Ruth; Lipsenthal, Lee; Finkel, Robert; Saunders, Donald; McCormac, Patty; Scheer, Judith M; Collins, Richard E; Guarneri, Erminia M; Ornish, Dean

    2006-05-01

    It is unclear whether patients with coronary artery disease (CAD) and diabetes mellitus (DM) can make comprehensive lifestyle changes that produce similar changes in coronary risk factors and quality of life compared with patients with CAD and without DM. We examined medical characteristics, lifestyle, and quality of life by diabetic status and gender in the Multicenter Lifestyle Demonstration Project (MLDP), a study of 440 nonsmoking patients with CAD (347 men, 55 with DM; 15.9%; 93 women, 36 with DM; 38.7%). Patients met in groups to improve lifestyle (plant-based, low-fat diet; exercise; stress management) for 1 year. Follow-ups were conducted at 3 and 12 months. At baseline, body mass and systolic blood pressure were significantly higher among patients with DM. Men with DM had a worse medical history (e.g., hypertension, hyperlipidemia, and family history of CAD) than did those without DM. Patients with DM, especially women, reported poorer quality of life than did patients without DM. The 2 groups of patients were able to adhere to the recommended lifestyle, as demonstrated by significant improvements in weight (mean -5 kg), body fat, low-density lipoprotein cholesterol, exercise capacity, and quality of life. No significant changes in triglycerides and high-density lipoprotein cholesterol were noted. By the end of 12 months, improvements in glucose-lowering medications (i.e., discontinuation or a change from insulin to oral hypoglycemic agents) were noted for 19.8% (n = 18) of patients with DM. In conclusion, patients with CAD and DM are able to follow a comprehensive lifestyle change program and show similar improvements in coronary risk factors and quality of life as those without DM. PMID:16635593

  11. Using full-reference image quality metrics for automatic image sharpening

    NASA Astrophysics Data System (ADS)

    Krasula, Lukas; Fliegel, Karel; Le Callet, Patrick; Klíma, Miloš

    2014-05-01

    Image sharpening is a post-processing technique employed for the artificial enhancement of the perceived sharpness by shortening the transitions between luminance levels or increasing the contrast on the edges. The greatest challenge in this area is to determine the level of perceived sharpness which is optimal for human observers. This task is complex because the enhancement is gained only until the certain threshold. After reaching it, the quality of the resulting image drops due to the presence of annoying artifacts. Despite the effort dedicated to the automatic sharpness estimation, none of the existing metrics is designed for localization of this threshold. Nevertheless, it is a very important step towards the automatic image sharpening. In this work, possible usage of full-reference image quality metrics for finding the optimal amount of sharpening is proposed and investigated. The intentionally over-sharpened "anchor image" was included to the calculation as the "anti-reference" and the final metric score was computed from the differences between reference, processed, and anchor versions of the scene. Quality scores obtained from the subjective experiment were used to determine the optimal combination of partial metric values. Five popular fidelity metrics - SSIM, MS-SSIM, IW-SSIM, VIF, and FSIM - were tested. The performance of the proposed approach was then verified in the subjective experiment.

  12. Elasticity imaging of arterial wall with transcutaneous ultrasound both in longitudinal-axis and short-axis planes

    NASA Astrophysics Data System (ADS)

    Kanai, Hiroshi; Hasegawa, Hideyuki

    2001-05-01

    A method for measuring regional elasticity of tissue surrounding atherosclerotic plaque is described. An ultrasonic beam was scanned with a conventional linear-type probe, and multiple layers were preset from luminal surface to adventitia of the common carotid artery (CCA) with intervals of 375 ?m. By applying the method [IEEE Trans. UFFC 46, 1229-1241 (1999)], a minute decrease of several tenths of a micrometer in thickness of each layer resulting from arrival of the pressure wave was determined. By assuming that the arterial wall is incompressible and that the blood pressure is applied normal to each layer, the elastic modulus in the circumferential direction of each layer was estimated at intervals of 75 ?m in the radial direction and 150-300 ?m in longitudinal direction. On the other hand, by designing the directions of ultrasonic beams so that each beam always passes through the center of the artery, the cross-sectional elasticity image in the short-axis plane was also obtained. Based on the elasticity library determined by comparing the elasticity distribution and their pathological images, each point was statistically categorized as lipid, a mixture of smooth muscle and collagen fiber, or other. By applying the method to the CCAs, soft inclusion of lipid was found for plaques.

  13. Analysis of filtering techniques and image quality in pixel duplicated images

    NASA Astrophysics Data System (ADS)

    Mehrubeoglu, Mehrube; McLauchlan, Lifford

    2009-08-01

    When images undergo filtering operations, valuable information can be lost besides the intended noise or frequencies due to averaging of neighboring pixels. When the image is enlarged by duplicating pixels, such filtering effects can be reduced and more information retained, which could be critical when analyzing image content automatically. Analysis of retinal images could reveal many diseases at early stage as long as minor changes that depart from a normal retinal scan can be identified and enhanced. In this paper, typical filtering techniques are applied to an early stage diabetic retinopathy image which has undergone digital pixel duplication. The same techniques are applied to the original images for comparison. The effects of filtering are then demonstrated for both pixel duplicated and original images to show the information retention capability of pixel duplication. Image quality is computed based on published metrics. Our analysis shows that pixel duplication is effective in retaining information on smoothing operations such as mean filtering in the spatial domain, as well as lowpass and highpass filtering in the frequency domain, based on the filter window size. Blocking effects due to image compression and pixel duplication become apparent in frequency analysis.

  14. [Complex estimation of the state of health, quality of life, level of psychological adaptation and rates of senescence of war veterans, suffering from arterial hypertension].

    PubMed

    Zakharova, N O; Iakovlev, O G; Treneva, E V

    2014-01-01

    The article presents some aspects of the health status of the veterans of the Samara region. Intercommunication is marked between the level of social adaptation, quality of life and rate aging combatants. The study shows the effect of chronic posttraumatic stress disorder on the occurrence of psychosomatic pathology and development of senescence combat veterans suffering from arterial hypertension. PMID:25051769

  15. Degraded visual environment image/video quality metrics

    NASA Astrophysics Data System (ADS)

    Baumgartner, Dustin D.; Brown, Jeremy B.; Jacobs, Eddie L.; Schachter, Bruce J.

    2014-06-01

    A number of image quality metrics (IQMs) and video quality metrics (VQMs) have been proposed in the literature for evaluating techniques and systems for mitigating degraded visual environments. Some require both pristine and corrupted imagery. Others require patterned target boards in the scene. None of these metrics relates well to the task of landing a helicopter in conditions such as a brownout dust cloud. We have developed and used a variety of IQMs and VQMs related to the pilot's ability to detect hazards in the scene and to maintain situational awareness. Some of these metrics can be made agnostic to sensor type. Not only are the metrics suitable for evaluating algorithm and sensor variation, they are also suitable for choosing the most cost effective solution to improve operating conditions in degraded visual environments.

  16. No-reference remote sensing image quality assessment using a comprehensive evaluation factor

    NASA Astrophysics Data System (ADS)

    Wang, Lin; Wang, Xu; Li, Xiao; Shao, Xiaopeng

    2014-05-01

    The conventional image quality assessment algorithm, such as Peak Signal to Noise Ratio ?PSNR?? Mean Square Error?MSE? and structural similarity (SSIM), needs the original image as a reference. It's not applicable to the remote sensing image for which the original image cannot be assumed to be available. In this paper, a No-reference Image Quality Assessment (NRIQA) algorithm is presented to evaluate the quality of remote sensing image. Since blur and noise (including the stripe noise) are the common distortion factors affecting remote sensing image quality, a comprehensive evaluation factor is modeled to assess the blur and noise by analyzing the image visual properties for different incentives combined with SSIM based on human visual system (HVS), and also to assess the stripe noise by using Phase Congruency (PC). The experiment results show this algorithm is an accurate and reliable method for Remote Sensing Image Quality Assessment.

  17. Influence of void on image quality of industrial SPECT

    NASA Astrophysics Data System (ADS)

    Park, J. G.; Jung, S. H.; Kim, J. B.; Moon, J.; Kim, C. H.

    2013-12-01

    Industrial single photon emission computed tomography (SPECT) is a promising technique to determine the dynamic behavior of industrial process media and has been developed in the Korea Atomic Energy Research Institute. The present study evaluated the influence of a void, which is presence in multiphase reactors of industrial process, on the image quality of an industrial SPECT. The results are very encouraging; that is, the performance of the industrial SPECT system is little influenced by the presence of a void, which means that industrial SPECT is an appropriate tool to estimate the dynamic characteristics of the process media in a water-air phase bubble column with a static gas sparger.

  18. Computerized method for evaluating diagnostic image quality of calcified plaque images in cardiac CT: Validation on a physical dynamic cardiac phantom

    PubMed Central

    King, Martin; Rodgers, Zachary; Giger, Maryellen L.; Bardo, Dianna M. E.; Patel, Amit R.

    2010-01-01

    Purpose: In cardiac computed tomography (CT), important clinical indices, such as the coronary calcium score and the percentage of coronary artery stenosis, are often adversely affected by motion artifacts. As a result, the expert observer must decide whether or not to use these indices during image interpretation. Computerized methods potentially can be used to assist in these decisions. In a previous study, an artificial neural network (ANN) regression model provided assessability (image quality) indices of calcified plaque images from the software NCAT phantom that were highly agreeable with those provided by expert observers. The method predicted assessability indices based on computer-extracted features of the plaque. In the current study, the ANN-predicted assessability indices were used to identify calcified plaque images with diagnostic calcium scores (based on mass) from a physical dynamic cardiac phantom. The basic assumption was that better quality images were associated with more accurate calcium scores. Methods: A 64-channel CT scanner was used to obtain 500 calcified plaque images from a physical dynamic cardiac phantom at different heart rates, cardiac phases, and plaque locations. Two expert observers independently provided separate sets of assessability indices for each of these images. Separate sets of ANN-predicted assessability indices tailored to each observer were then generated within the framework of a bootstrap resampling scheme. For each resampling iteration, the absolute calcium score error between the calcium scores of the motion-contaminated plaque image and its corresponding stationary image served as the ground truth in terms of indicating images with diagnostic calcium scores. The performances of the ANN-predicted and observer-assigned indices in identifying images with diagnostic calcium scores were then evaluated using ROC analysis. Results: Assessability indices provided by the first observer and the corresponding ANN performed similarly (AUCOBS1=0.80 [0.73,0.86] vs AUCANN1=0.88 [0.82,0.92]) as that of the second observer and the corresponding ANN (AUCOBS2=0.87 [0.83,0.91] vs AUCANN2=0.90 [0.85,0.94]). Moreover, the ANN-predicted indices were generated in a fraction of the time required to obtain the observer-assigned indices. Conclusions: ANN-predicted assessability indices performed similar to observer-assigned assessability indices in identifying images with diagnostic calcium scores from the physical dynamic cardiac phantom. The results of this study demonstrate the potential of using computerized methods for identifying images with diagnostic clinical indices in cardiac CT images. PMID:21158289

  19. Computerized method for evaluating diagnostic image quality of calcified plaque images in cardiac CT: Validation on a physical dynamic cardiac phantom

    SciTech Connect

    King, Martin; Rodgers, Zachary; Giger, Maryellen L.; Bardo, Dianna M. E.; Patel, Amit R. [Department of Radiology, Committee on Medical Physics, University of Chicago, 5841 South Maryland Avenue, MC 2026, Chicago, Illinois 60637 (United States); Department of Diagnostic Radiology, Oregon Health and Science University, 3181 Southwest Sam Jackson Park Road, Portland, Oregon 97239 (United States); Department of Medicine, University of Chicago, 5841 South Maryland Avenue, MC 5084, Chicago, Illinois 60637 (United States)

    2010-11-15

    Purpose: In cardiac computed tomography (CT), important clinical indices, such as the coronary calcium score and the percentage of coronary artery stenosis, are often adversely affected by motion artifacts. As a result, the expert observer must decide whether or not to use these indices during image interpretation. Computerized methods potentially can be used to assist in these decisions. In a previous study, an artificial neural network (ANN) regression model provided assessability (image quality) indices of calcified plaque images from the software NCAT phantom that were highly agreeable with those provided by expert observers. The method predicted assessability indices based on computer-extracted features of the plaque. In the current study, the ANN-predicted assessability indices were used to identify calcified plaque images with diagnostic calcium scores (based on mass) from a physical dynamic cardiac phantom. The basic assumption was that better quality images were associated with more accurate calcium scores. Methods: A 64-channel CT scanner was used to obtain 500 calcified plaque images from a physical dynamic cardiac phantom at different heart rates, cardiac phases, and plaque locations. Two expert observers independently provided separate sets of assessability indices for each of these images. Separate sets of ANN-predicted assessability indices tailored to each observer were then generated within the framework of a bootstrap resampling scheme. For each resampling iteration, the absolute calcium score error between the calcium scores of the motion-contaminated plaque image and its corresponding stationary image served as the ground truth in terms of indicating images with diagnostic calcium scores. The performances of the ANN-predicted and observer-assigned indices in identifying images with diagnostic calcium scores were then evaluated using ROC analysis. Results: Assessability indices provided by the first observer and the corresponding ANN performed similarly (AUC{sub OBS1}=0.80 [0.73,0.86] vs AUC{sub ANN1}=0.88 [0.82,0.92]) as that of the second observer and the corresponding ANN (AUC{sub OBS2}=0.87 [0.83,0.91] vs AUC{sub ANN2}=0.90 [0.85,0.94]). Moreover, the ANN-predicted indices were generated in a fraction of the time required to obtain the observer-assigned indices. Conclusions: ANN-predicted assessability indices performed similar to observer-assigned assessability indices in identifying images with diagnostic calcium scores from the physical dynamic cardiac phantom. The results of this study demonstrate the potential of using computerized methods for identifying images with diagnostic clinical indices in cardiac CT images.

  20. Quality control of VMAT synchronization using portal imaging.

    PubMed

    Bedford, James L; Chajecka-Szczygielska, Honorata; Thomas, Michael D R

    2015-01-01

    For accurate delivery of volumetric-modulated arc therapy (VMAT), the gantry position should be synchronized with the multileaf collimator (MLC) leaf positions and the dose rate. This study, therefore, aims to implement quality control (QC) of VMAT synchronization, with as few arcs as possible and with minimal data handling time, using portal imaging. A steel bar of diameter 12 mm is accurately positioned in the G-T direction, 80 mm laterally from the isocenter. An arc prescription irradiates the bar with a 16 mm × 220 mm field during a complete 360° arc, so as to cast a shadow of the bar onto the portal imager. This results in a sinusoidal sweep of the field and shadow across the portal imager and back. The method is evaluated by simulating gantry position errors of 1°-9° at one control point, dose errors of 2 monitor units to 20 monitor units (MU) at one control point (0.3%-3% overall), and MLC leaf position errors of 1 mm - 6 mm at one control point. Inhomogeneity metrics are defined to characterize the synchronization of all leaves and of individual leaves with respect to the complete set. Typical behavior is also investigated for three models of accelerator. In the absence of simulated errors, the integrated images show uniformity, and with simulated delivery errors, irregular patterns appear. The inhomogeneity metrics increase by 67% due to a 4° gantry position error, 33% due to an 8 MU (1.25%) dose error, and 70% due to a 2 mm MLC leaf position error. The method is more sensitive to errors at gantry angle 90°/270° than at 0°/180° due to the geometry of the test. This method provides fast and effective VMAT QC suitable for inclusion in a monthly accelerator QC program. The test is able to detect errors in the delivery of individual control points, with the possibility of using movie images to further investigate suspicious image features. PMID:25679179

  1. Assessment of image quality in x-ray radiography imaging using a small plasma focus device

    NASA Astrophysics Data System (ADS)

    Kanani, A.; Shirani, B.; Jabbari, I.; Mokhtari, J.

    2014-08-01

    This paper offers a comprehensive investigation of image quality parameters for a small plasma focus as a pulsed hard x-ray source for radiography applications. A set of images were captured from some metal objects and electronic circuits using a low energy plasma focus at different voltages of capacitor bank and different pressures of argon gas. The x-ray source focal spot of this device was obtained to be about 0.6 mm using the penumbra imaging method. The image quality was studied by several parameters such as image contrast, line spread function (LSF) and modulation transfer function (MTF). Results showed that the contrast changes by variations in gas pressure. The best contrast was obtained at a pressure of 0.5 mbar and 3.75 kJ stored energy. The results of x-ray dose from the device showed that about 0.6 mGy is sufficient to obtain acceptable images on the film. The measurements of LSF and MTF parameters were carried out by means of a thin stainless steel wire 0.8 mm in diameter and the cut-off frequency was obtained to be about 1.5 cycles/mm.

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

    SciTech Connect

    Tsetis, Dimitrios [University Hospital of Heraklion, Medical School of Crete, Department of Radiology (Greece)], E-mail: tsetis@med.uoc.gr; Uberoi, Raman [John Radcliffe Hospital, Department of Radiology (United Kingdom)

    2008-03-15

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

  3. Arterial Spin-labeling MR Imaging of Renal Masses: Correlation with Histopathologic Findings

    PubMed Central

    Lanzman, Rotem S.; Robson, Phil M.; Sun, Maryellen R.; Patel, Amish D.; Mentore, Kimiknu; Wagner, Andrew A.; Genega, Elizabeth M.; Rofsky, Neil M.; Alsop, David C.

    2012-01-01

    Purpose: To assess the value of arterial spin-labeling (ASL) perfusion magnetic resonance (MR) imaging in the characterization of solid renal masses by using histopathologic findings as the standard of reference. Materials and Methods: This prospective study was compliant with HIPAA and approved by the institutional review board. Informed consent was obtained from all patients before imaging. Forty-two consecutive patients suspected of having renal masses underwent ASL MR imaging before their routine 1.5-T clinical MR examination. Mean and peak tumor perfusion levels were obtained by one radiologist, who was blinded to the final histologic diagnosis, by using region of interest analysis. Perfusion values were correlated with histopathologic findings by using analysis of variance. A linear correlation model was used to evaluate the relationship between tumor size and perfusion in clear cell renal cell carcinoma (RCC). P < .05 was considered indicative of a statistically significant difference. Results: Histopathologic findings were available in 34 patients (28 men, six women; mean age ± standard deviation, 60.4 years ± 11.7). The mean perfusion of papillary RCC (27.0 mL/min/100 g ± 15.1) was lower than that of clear cell RCC (171.6 mL/min/100 g ± 61.2, P = .001), chromophobe RCC (152.9 mL/min/100 g ± 80.7, P = .04), unclassified RCC (208.0 mL/min/100 g ± 41.1, P = .001), and oncocytoma (373.9 mL/min/100 g ± 99.2, P < .001). The mean and peak perfusion levels of oncocytoma (373.9 mL/min/100 g ± 99.2 and 512.3 mL/min/100 g ± 146.0, respectively) were higher than those of papillary RCC (27.0 mL/min/100 g ± 15.1 and 78.2 mL/min/100 g ± 39.7, P < .001 for both), chromophobe RCC (152.9 mL/min/100 g ± 80.7 and 260.9 mL/min/100 g ± 61.9; P < .001 and P = .02, respectively), and unclassified RCC (208.0 mL/min/100 g ± 41.1 and 273.3 mL/min/100 g ± 83.4; P = .01 and P = .03, respectively). The mean tumor perfusion of oncocytoma was higher than that of clear cell RCC (P < .001). Conclusion: ASL MR imaging enables distinction among different histopathologic diagnoses in renal masses on the basis of their perfusion level. Oncocytomas demonstrate higher perfusion levels than RCCs, and papillary RCCs exhibit lower perfusion levels than other RCC subtypes. © RSNA, 2012 PMID:23047841

  4. User-guided automated segmentation of time-series ultrasound images for measuring vasoreactivity of the brachial artery induced by flow mediation

    NASA Astrophysics Data System (ADS)

    Sehgal, Chandra M.; Kao, Yen H.; Cary, Ted W.; Arger, Peter H.; Mohler, Emile R.

    2005-04-01

    Endothelial dysfunction in response to vasoactive stimuli is closely associated with diseases such as atherosclerosis, hypertension and congestive heart failure. The current method of using ultrasound to image the brachial artery along the longitudinal axis is insensitive for measuring the small vasodilatation that occurs in response to flow mediation. The goal of this study is to overcome this limitation by using cross-sectional imaging of the brachial artery in conjunction with the User-Guided Automated Boundary Detection (UGABD) algorithm for extracting arterial boundaries. High-resolution ultrasound imaging was performed on rigid plastic tubing, on elastic rubber tubing phantoms with steady and pulsatile flow, and on the brachial artery of a healthy volunteer undergoing reactive hyperemia. The area of cross section of time-series images was analyzed by UGABD by propagating the boundary from one frame to the next. The UGABD results were compared by linear correlation with those obtained by manual tracing. UGABD measured the cross-sectional area of the phantom tubing to within 5% of the true area. The algorithm correctly detected pulsatile vasomotion in phantoms and in the brachial artery. A comparison of area measurements made using UGABD with those made by manual tracings yielded a correlation of 0.9 and 0.8 for phantoms and arteries, respectively. The peak vasodilatation due to reactive hyperemia was two orders of magnitude greater in pixel count than that measured by longitudinal imaging. Cross-sectional imaging is more sensitive than longitudinal imaging for measuring flow-mediated dilatation of brachial artery, and thus may be more suitable for evaluating endothelial dysfunction.

  5. Image quality and stability of image-guided radiotherapy (IGRT) devices: A comparative study

    PubMed Central

    Stock, Markus; Pasler, Marlies; Birkfellner, Wolfgang; Homolka, Peter; Poetter, Richard; Georg, Dietmar

    2010-01-01

    Introduction Our aim was to implement standards for quality assurance of IGRT devices used in our department and to compare their performances with that of a CT simulator. Materials and methods We investigated image quality parameters for three devices over a period of 16 months. A multislice CT was used as a benchmark and results related to noise, spatial resolution, low contrast visibility (LCV) and uniformity were compared with a cone beam CT (CBCT) at a linac and simulator. Results All devices performed well in terms of LCV and, in fact, exceeded vendor specifications. MTF was comparable between CT and linac CBCT. Integral nonuniformity was, on average, 0.002 for the CT and 0.006 for the linac CBCT. Uniformity, LCV and MTF varied depending on the protocols used for the linac CBCT. Contrast-to-noise ratio was an average of 51% higher for the CT than for the linac and simulator CBCT. No significant time trend was observed and tolerance limits were implemented. Discussion Reasonable differences in image quality between CT and CBCT were observed. Further research and development are necessary to increase image quality of commercially available CBCT devices in order for them to serve the needs for adaptive and/or online planning. PMID:19695725

  6. Improved diagnostic performance of exercise thallium-201 single photon emission computed tomography over planar imaging in the diagnosis of coronary artery disease: a receiver operating characteristic analysis

    SciTech Connect

    Fintel, D.J.; Links, J.M.; Brinker, J.A.; Frank, T.L.; Parker, M.; Becker, L.C.

    1989-03-01

    Qualitative interpretation of tomographic and planar scintigrams, a five point rating scale and receiver operating characteristic analysis were utilized to compare single photon emission computed tomography and conventional planar imaging of myocardial thallium-201 uptake in the accuracy of the diagnosis of coronary artery disease and individual vessel involvement. One hundred twelve patients undergoing cardiac catheterization and 23 normal volunteers performed symptom-limited treadmill exercise, followed by stress and redistribution imaging by both tomographic and planar techniques, with the order determined randomly. Paired receiver operating characteristic curves revealed that single photon emission computed tomography was more accurate than planar imaging over the entire range of decision thresholds for the overall detection and exclusion of coronary artery disease and involvement of the left anterior descending and left circumflex coronary arteries. Tomography offered relatively greater advantages in male patients and in patients with milder forms of coronary artery disease, who had no prior myocardial infarction, only single vessel involvement or no lesion greater than or equal to 50 to 69%. Tomography did not appear to provide improved diagnosis in women or in detection of disease in the right coronary artery. Although overall detection of coronary artery disease was not improved in patients with prior myocardial infarction, tomography provided improved identification of normal and abnormal vascular regions. These results indicate that single photon emission computed tomography provides improved diagnostic performance compared with planar imaging in many clinical subgroups.

  7. Blood Flow Vortices along the Main Pulmonary Artery Measured with MR Imaging for Diagnosis of Pulmonary Hypertension.

    PubMed

    Reiter, Gert; Reiter, Ursula; Kovacs, Gabor; Olschewski, Horst; Fuchsjäger, Michael

    2015-04-01

    Purpose To approximate the functional relationship between invasively measured mean pulmonary arterial pressure (mPAP) and the phase-contrast magnetic resonance (MR) imaging-derived duration of vortical blood flow along the main pulmonary artery and to analyze its applicability for noninvasive diagnosis of pulmonary hypertension (PH) and borderline mPAP. Materials and Methods The local ethics review board approved this prospective study of 145 patients suspected of having PH (69 patients with PH, 19 patients with borderline mPAP, and 57 patients with normal mPAP) who underwent right heart catheterization (RHC) and three-directional phase-contrast MR imaging of the main pulmonary artery. Velocity fields were viewed with dedicated software and evaluated for the duration of vortical blood flow in the main pulmonary artery (tvortex, the percentage of cardiac phases with vortex present). The relationship between mPAP at RHC and tvortex was assessed by means of a segmented linear regression model, and by Bland-Altman and receiver operating characteristic curve analyses. Results The relationship between mPAP and tvortex was described adequately (R(2) = 0.95) as linearly increasing, from tvortex of 0% (mPAP ? 16.0 mm Hg) with a slope of 1.59% per millimeter of mercury. The standard deviation between mPAP values derived from RHC and those estimated by using tvortex was 3.9 mm Hg. The area under the curve for tvortex-based diagnosis of PH was 0.994 (95% confidence interval [CI]: 0.982, 0.998), and the calculated PH cut-off value (tvortex ? 14.3%) resulted in sensitivity of 0.97 (95% CI: 0.90, 0.99) and specificity of 0.96 (95% CI: 0.89, 0.99). Vortical blood flow with tvortex less than 14.3% was specific for borderline mPAP. Conclusion Duration of vortical blood flow in the main pulmonary artery that is determined by using phase-contrast MR imaging allows accurate estimation of elevated mPAP and diagnosis of PH. © RSNA, 2014 Clinical trial registration no. NCT00575692. PMID:25372980

  8. Principles and Applications of Hyperspectral Imaging in Quality Evaluation of Agro-Food Products: A Review

    Microsoft Academic Search

    Gamal Elmasry; Mohammed Kamruzzaman; Da-Wen Sun; Paul Allen

    2012-01-01

    The requirements of reliability, expeditiousness, accuracy, consistency, and simplicity for quality assessment of food products encouraged the development of non-destructive technologies to meet the demands of consumers to obtain superior food qualities. Hyperspectral imaging is one of the most promising techniques currently investigated for quality evaluation purposes in numerous sorts of applications. The main advantage of the hyperspectral imaging system

  9. The Impact of Image Quality on the Performance of Face Recognition

    Microsoft Academic Search

    Abhishek Dutta; Raymond Veldhuis; Luuk Spreeuwers

    2012-01-01

    The performance of a face recognition system depends on the quality of both test and reference images participating in the face comparison process. In a forensic evaluation case involving face recognition, we do not have any control over the quality of the trace (image captured by a CCTV at a crime scene) and it is usually of very low quality.

  10. Cone beam computed tomography radiation dose and image quality assessments.

    PubMed

    Lofthag-Hansen, Sara

    2010-01-01

    Diagnostic radiology has undergone profound changes in the last 30 years. New technologies are available to the dental field, cone beam computed tomography (CBCT) as one of the most important. CBCT is a catch-all term for a technology comprising a variety of machines differing in many respects: patient positioning, volume size (FOV), radiation quality, image capturing and reconstruction, image resolution and radiation dose. When new technology is introduced one must make sure that diagnostic accuracy is better or at least as good as the one it can be expected to replace. The CBCT brand tested was two versions of Accuitomo (Morita, Japan): 3D Accuitomo with an image intensifier as detector, FOV 3 cm x 4 cm and 3D Accuitomo FPD with a flat panel detector, FOVs 4 cm x 4 cm and 6 cm x 6 cm. The 3D Accuitomo was compared with intra-oral radiography for endodontic diagnosis in 35 patients with 46 teeth analyzed, of which 41 were endodontically treated. Three observers assessed the images by consensus. The result showed that CBCT imaging was superior with a higher number of teeth diagnosed with periapical lesions (42 vs 32 teeth). When evaluating 3D Accuitomo examinations in the posterior mandible in 30 patients, visibility of marginal bone crest and mandibular canal, important anatomic structures for implant planning, was high with good observer agreement among seven observers. Radiographic techniques have to be evaluated concerning radiation dose, which requires well-defined and easy-to-use methods. Two methods: CT dose index (CTDI), prevailing method for CT units, and dose-area product (DAP) were evaluated for calculating effective dose (E) for both units. An asymmetric dose distribution was revealed when a clinical situation was simulated. Hence, the CTDI method was not applicable for these units with small FOVs. Based on DAP values from 90 patient examinations effective dose was estimated for three diagnostic tasks: implant planning in posterior mandible and examinations of impacted lower third molars and retained upper cuspids. It varied between 11-77 microSv. Radiation dose should be evaluated together with image quality. Images of a skull phantom were obtained with both units varying tube voltage, tube current, degree of rotation and FOVs. Seven observers assessed subjective image quality using a six-point rating scale for two diagnostic tasks: periapical diagnosis and implant planning in the posterior part of the jaws. Intra-observer agreement was good and inter-observer agreement moderate. Periapical diagnosis was found to, regardless of jaw, require higher exposure parameters compared to implant planning. Implant planning in the lower jaw required higher exposure parameters compared to upper jaw. Substantial dose reduction could be made without loss of diagnostic information by using a rotation of 180 degrees, in particular implant planning in upper jaw. CBCT with small FOVs was found to be well-suited for periapical diagnosis and implant planning. The CTDI method is not applicable estimating effective dose for these units. Based on DAP values effective dose varied between 11-77 microSv (ICRP 60, 1991) in a retrospectively selected patient material. Adaptation of exposure parameters to diagnostic task can give substantial dose reduction. PMID:21229915

  11. Frame-rate analysis of arterial blood flow in human and rat using laser speckle image sensing

    NASA Astrophysics Data System (ADS)

    Yokoi, Naomichi; Sato, Junki; Shimatani, Yuichi; Kyoso, Masaki; Funamizu, Hideki; Aizu, Yoshihisa

    2014-05-01

    In imaging of blood flow by means of a laser speckle technique, we have proposed so far an estimation parameter based on the spatial contrast of speckle patterns observed for the blood flow in skin tissue and a blood vessel. This parameter enable us to image a relative blood flow distribution from a single speckle pattern, thus, it analyzes the blood flow with a frame-rate of an imaging device used. In this study, we investigated availability of this parameter for detecting changes in arterial blood flow caused by medication and cold stimulation to the skin tissue. Experiments were conducted for an anesthetized rat and a human wrist to confirm the feasibility of the present parameter.

  12. Task-based measures of image quality and their relation to radiation dose and patient risk

    NASA Astrophysics Data System (ADS)

    Barrett, Harrison H.; Myers, Kyle J.; Hoeschen, Christoph; Kupinski, Matthew A.; Little, Mark P.

    2015-01-01

    The theory of task-based assessment of image quality is reviewed in the context of imaging with ionizing radiation, and objective figures of merit (FOMs) for image quality are summarized. The variation of the FOMs with the task, the observer and especially with the mean number of photons recorded in the image is discussed. Then various standard methods for specifying radiation dose are reviewed and related to the mean number of photons in the image and hence to image quality. Current knowledge of the relation between local radiation dose and the risk of various adverse effects is summarized, and some graphical depictions of the tradeoffs between image quality and risk are introduced. Then various dose-reduction strategies are discussed in terms of their effect on task-based measures of image quality.

  13. Task-based measures of image quality and their relation to radiation dose and patient risk.

    PubMed

    Barrett, Harrison H; Myers, Kyle J; Hoeschen, Christoph; Kupinski, Matthew A; Little, Mark P

    2015-01-21

    The theory of task-based assessment of image quality is reviewed in the context of imaging with ionizing radiation, and objective figures of merit (FOMs) for image quality are summarized. The variation of the FOMs with the task, the observer and especially with the mean number of photons recorded in the image is discussed. Then various standard methods for specifying radiation dose are reviewed and related to the mean number of photons in the image and hence to image quality. Current knowledge of the relation between local radiation dose and the risk of various adverse effects is summarized, and some graphical depictions of the tradeoffs between image quality and risk are introduced. Then various dose-reduction strategies are discussed in terms of their effect on task-based measures of image quality. PMID:25564960

  14. Diffusion imaging quality control via entropy of principal direction distribution

    PubMed Central

    Oguz, Ipek; Smith, Rachel G.; Verde, Audrey R.; Dietrich, Cheryl; Gupta, Aditya; Escolar, Maria L.; Piven, Joseph; Pujol, Sonia; Vachet, Clement; Gouttard, Sylvain; Gerig, Guido; Dager, Stephen; McKinstry, Robert C.; Paterson, Sarah; Evans, Alan C.; Styner, Martin A.

    2013-01-01

    Diffusion MR imaging has received increasing attention in the neuroimaging community, as it yields new insights into the microstructural organization of white matter that are not available with conventional MRI techniques. While the technology has enormous potential, diffusion MRI suffers from a unique and complex set of image quality problems, limiting the sensitivity of studies and reducing the accuracy of findings. Furthermore, the acquisition time for diffusion MRI is longer than conventional MRI due to the need for multiple acquisitions to obtain directionally encoded Diffusion Weighted Images (DWI). This leads to increased motion artifacts, reduced signal-to-noise ratio (SNR), and increased proneness to a wide variety of artifacts, including eddy-current and motion artifacts, “venetian blind” artifacts, as well as slice-wise and gradient-wise inconsistencies. Such artifacts mandate stringent Quality Control (QC) schemes in the processing of diffusion MRI data. Most existing QC procedures are conducted in the DWI domain and/or on a voxel level, but our own experiments show that these methods often do not fully detect and eliminate certain types of artifacts, often only visible when investigating groups of DWI's or a derived diffusion model, such as the most-employed diffusion tensor imaging (DTI). Here, we propose a novel regional QC measure in the DTI domain that employs the entropy of the regional distribution of the principal directions (PD). The PD entropy quantifies the scattering and spread of the principal diffusion directions and is invariant to the patient's position in the scanner. High entropy value indicates that the PDs are distributed relatively uniformly, while low entropy value indicates the presence of clusters in the PD distribution. The novel QC measure is intended to complement the existing set of QC procedures by detecting and correcting residual artifacts. Such residual artifacts cause directional bias in the measured PD and here called dominant direction artifacts. Experiments show that our automatic method can reliably detect and potentially correct such artifacts, especially the ones caused by the vibrations of the scanner table during the scan. The results further indicate the usefulness of this method for general quality assessment in DTI studies. PMID:23684874

  15. “Lucky Averaging”: Quality improvement on Adaptive Optics Scanning Laser Ophthalmoscope Images

    PubMed Central

    Huang, Gang; Zhong, Zhangyi; Zou, Weiyao; Burns, Stephen A.

    2012-01-01

    Adaptive optics(AO) has greatly improved retinal image resolution. However, even with AO, temporal and spatial variations in image quality still occur due to wavefront fluctuations, intra-frame focus shifts and other factors. As a result, aligning and averaging images can produce a mean image that has lower resolution or contrast than the best images within a sequence. To address this, we propose an image post-processing scheme called “lucky averaging”, analogous to lucky imaging (Fried, 1978) based on computing the best local contrast over time. Results from eye data demonstrate improvements in image quality. PMID:21964097

  16. Quantitative image quality analysis of a nonlinear spatio-temporal filter

    Microsoft Academic Search

    Francisco J. Sánchez-marin; Yogesh Srinivas; Kadri N. Jabri; David L. Wilson

    2001-01-01

    Digital temporal and spatial filtering of fluoroscopic image sequences can be used to improve the quality of images acquired at low X-ray exposure. In this study, we characterized a nonlinear edge preserving, spatio-temporal noise reduction filter, the bidirectional multistage (BMS) median filter of Arce (1991). To assess image quality, signal detection and discrimination experiments were performed on stationary targets using

  17. A Novel Approach For Segmentation of Good, Normal and Bad Quality Fingerprint Image

    Microsoft Academic Search

    S. S. Jambhorkar; R. R. Manza; S. S. Gornale; K. V. Kale

    2006-01-01

    A novel approach for segmentation of good, normal and bad quality fingerprint image is proposed in this paper. Which is different from traditional methods that usually use certain features to segment diversified image. This work is divided in three steps: firstly, we enhance the quality of image to remove great many false traces effectively and got a uniform background. Secondly,

  18. Image Quality, Tissue Heating, and Frame Rate Trade-offs in Acoustic Radiation Force Impulse Imaging

    PubMed Central

    Bouchard, Richard R.; Dahl, Jeremy J.; Hsu, stephen J.; Palmeri, Mark L.; Trahey, Gregg E.

    2013-01-01

    The real-time application of acoustic radiation force impulse (ARFI) imaging requires both short acquisition times for a single ARFI image and repeated acquisition of these frames. Due to the high energy of pulses required to generate appreciable radiation force, however, repeated acquisitions could result in substantial transducer face and tissue heating. We describe and evaluate several novel beam sequencing schemes which, along with parallel-receive acquisition, are designed to reduce acquisition time and heating. These techniques reduce the total number of radiation force impulses needed to generate an image and minimize the time between successive impulses. We present qualitative and quantitative analyses of the trade-offs in image quality resulting from the acquisition schemes. Results indicate that these techniques yield a significant improvement in frame rate with only moderate decreases in image quality. Tissue and transducer face heating resulting from these schemes is assessed through finite element method modeling and thermocouple measurements. Results indicate that heating issues can be mitigated by employing ARFI acquisition sequences that utilize the highest track-to-excitation ratio possible. PMID:19213633

  19. Image quality evaluation of the angiography imaging system at the European synchrotron radiation facility

    NASA Astrophysics Data System (ADS)

    Peterzol, A.; Bravin, A.; Coan, P.; Elleaume, H.

    2003-09-01

    The evaluation of the image quality of the angiography imaging system used at the Medical Beamline of European Synchrotron Radiation Facility (ESRF) is presented. A two-line 432-pixel germanium detector is utilized in the human coronary angiography program. The performances have been measured with two monochromatic beams, with energies above and below the iodine K-edge. The large-area transfer characteristics (response curve), the spatial detail transfer performance (modulation transfer function (MTF)) and the noise properties (noise power spectrum (NPS)) have been measured and used to compute the frequency-dependent detective quantum efficiency DQE of the system.

  20. Three dimensional level set based semiautomatic segmentation of atherosclerotic carotid artery wall volume using 3D ultrasound imaging

    NASA Astrophysics Data System (ADS)

    Hossain, Md. Murad; AlMuhanna, Khalid; Zhao, Limin; Lal, Brajesh K.; Sikdar, Siddhartha

    2014-03-01

    3D segmentation of carotid plaque from ultrasound (US) images is challenging due to image artifacts and poor boundary definition. Semiautomatic segmentation algorithms for calculating vessel wall volume (VWV) have been proposed for the common carotid artery (CCA) but they have not been applied on plaques in the internal carotid artery (ICA). In this work, we describe a 3D segmentation algorithm that is robust to shadowing and missing boundaries. Our algorithm uses distance regularized level set method with edge and region based energy to segment the adventitial wall boundary (AWB) and lumen-intima boundary (LIB) of plaques in the CCA, ICA and external carotid artery (ECA). The algorithm is initialized by manually placing points on the boundary of a subset of transverse slices with an interslice distance of 4mm. We propose a novel user defined stopping surface based energy to prevent leaking of evolving surface across poorly defined boundaries. Validation was performed against manual segmentation using 3D US volumes acquired from five asymptomatic patients with carotid stenosis using a linear 4D probe. A pseudo gold-standard boundary was formed from manual segmentation by three observers. The Dice similarity coefficient (DSC), Hausdor distance (HD) and modified HD (MHD) were used to compare the algorithm results against the pseudo gold-standard on 1205 cross sectional slices of 5 3D US image sets. The algorithm showed good agreement with the pseudo gold standard boundary with mean DSC of 93.3% (AWB) and 89.82% (LIB); mean MHD of 0.34 mm (AWB) and 0.24 mm (LIB); mean HD of 1.27 mm (AWB) and 0.72 mm (LIB). The proposed 3D semiautomatic segmentation is the first step towards full characterization of 3D plaque progression and longitudinal monitoring.

  1. Open source database of images DEIMOS: extension for large-scale subjective image quality assessment

    NASA Astrophysics Data System (ADS)

    Vítek, Stanislav

    2014-09-01

    DEIMOS (Database of Images: Open Source) is an open-source database of images and video sequences for testing, verification and comparison of various image and/or video processing techniques such as compression, reconstruction and enhancement. This paper deals with extension of the database allowing performing large-scale web-based subjective image quality assessment. Extension implements both administrative and client interface. The proposed system is aimed mainly at mobile communication devices, taking into account advantages of HTML5 technology; it means that participants don't need to install any application and assessment could be performed using web browser. The assessment campaign administrator can select images from the large database and then apply rules defined by various test procedure recommendations. The standard test procedures may be fully customized and saved as a template. Alternatively the administrator can define a custom test, using images from the pool and other components, such as evaluating forms and ongoing questionnaires. Image sequence is delivered to the online client, e.g. smartphone or tablet, as a fully automated assessment sequence or viewer can decide on timing of the assessment if required. Environmental data and viewing conditions (e.g. illumination, vibrations, GPS coordinates, etc.), may be collected and subsequently analyzed.

  2. Quality Enhancement and Nerve Fibre Layer Artefacts Removal in Retina Fundus Images by Off Axis Imaging

    SciTech Connect

    Giancardo, Luca [ORNL] [ORNL; Meriaudeau, Fabrice [ORNL] [ORNL; Karnowski, Thomas Paul [ORNL] [ORNL; Li, Yaquin [University of Tennessee, Knoxville (UTK)] [University of Tennessee, Knoxville (UTK); Tobin Jr, Kenneth William [ORNL] [ORNL; Chaum, Edward [University of Tennessee, Knoxville (UTK)] [University of Tennessee, Knoxville (UTK)

    2011-01-01

    Retinal fundus images acquired with non-mydriatic digital fundus cameras are a versatile tool for the diagnosis of various retinal diseases. Because of the ease of use of newer camera models and their relative low cost, these cameras are employed worldwide by retina specialists to diagnose diabetic retinopathy and other degenerative diseases. Even with relative ease of use, the images produced by these systems sometimes suffer from reflectance artefacts mainly due to the nerve fibre layer (NFL) or other camera lens related reflections. We propose a technique that employs multiple fundus images acquired from the same patient to obtain a single higher quality image without these reflectance artefacts. The removal of bright artefacts, and particularly of NFL reflectance, can have great benefits for the reduction of false positives in the detection of retinal lesions such as exudate, drusens and cotton wool spots by automatic systems or manual inspection. If enough redundant information is provided by the multiple images, this technique also compensates for a suboptimal illumination. The fundus images are acquired in straightforward but unorthodox manner, i.e. the stare point of the patient is changed between each shot but the camera is kept fixed. Between each shot, the apparent shape and position of all the retinal structures that do not exhibit isotropic reflectance (e.g. bright artefacts) change. This physical effect is exploited by our algorithm in order to extract the pixels belonging to the inner layers of the retina, hence obtaining a single artefacts-free image.

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

    SciTech Connect

    Froeling, V., E-mail: Vera.Froeling@charite.de; Scheurig-Muenkler, C., E-mail: Christian.Scheurig@charite.de; Hamm, B., E-mail: Bernd.Hamm@charite.de; Kroencke, T. J., E-mail: thomas.kroencke@charite.de [Charite-Universitaetsmedizin Berlin, Department of Radiology (Germany)

    2012-06-15

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

  4. NOTE: Development of a quality assurance protocol for peripheral subtraction imaging applications

    NASA Astrophysics Data System (ADS)

    Walsh, C.; Murphy, D.; O'Hare, N.

    2002-04-01

    Peripheral subtraction scanning is used to trace the blood vessels of upper and lower extremities. In some modern C-arm fluoroscopy systems this function is performed automatically. In this mode the system is programmed to advance and stop in a series of steps taking a mask image at each point. The system then repeats each step after the contrast agent has been injected, and produces a DSA image at each point. Current radiographic quality assurance protocols do not address this feature. This note reviews methods of measuring system vibration while images are being acquired in automated peripheral stepping. The effect on image quality pre- and post-image processing is assessed. Results show that peripheral stepping DSA does not provide the same degree of image quality as static DSA. In examining static test objects, the major cause of the reduction in image quality is misregistration due to vibration of the image intensifier during imaging.

  5. In-flight assessment of SPOT5 image quality

    NASA Astrophysics Data System (ADS)

    Meygret, Aime; Fratter, Claude; Breton, Eric; Cabot, Francois; Laubies, Marie-Christine; Hourcastagnou, Jean-Noel

    2003-04-01

    SPOT5, the fifth satellite of the SPOT remote sensing satellite family was successfully launched on the 4th of May 2002. SPOT5 is designed to ensure continuity of data acquisition and space image services but also to provide users with advanced products. It flies two identical cameras named HRG (High Resolution Geometry) providing a 2.5 m and a 5 m resolution in a panchromatic mode and a 10 m resolution in a multi-spectral mode, still keeping a 60-km ground field. Stereo application is part two of the SPOT5 mission; the satellite flies a specific High Resolution Stereo instrument (HRS) made up of two telescopes allowing a 20° fore view and a 20° aft view over a 120-km swath, sampling the landscape every 5m. VEGETATION2, a wide field of view imaging radiometer complements the mission thanks to its daily coverage of the earth. The paper presents the mission, the commissioning phase that followed the satellite launch, the assessment of the image quality and the first calibration results.

  6. Automatic detection of the carotid artery boundary on cross-sectional MR image sequences using a circle model guided dynamic programming

    PubMed Central

    2011-01-01

    Background Systematic aerobe training has positive effects on the compliance of dedicated arterial walls. The adaptations of the arterial structure and function are associated with the blood flow-induced changes of the wall shear stress which induced vascular remodelling via nitric oxide delivered from the endothelial cell. In order to assess functional changes of the common carotid artery over time in these processes, a precise measurement technique is necessary. Before this study, a reliable, precise, and quick method to perform this work is not present. Methods We propose a fully automated algorithm to analyze the cross-sectional area of the carotid artery in MR image sequences. It contains two phases: (1) position detection of the carotid artery, (2) accurate boundary identification of the carotid artery. In the first phase, we use intensity, area size and shape as features to discriminate the carotid artery from other tissues and vessels. In the second phase, the directional gradient, Hough transform, and circle model guided dynamic programming are used to identify the boundary accurately. Results We test the system stability using contrast degraded images (contrast resolutions range from 50% to 90%). The unsigned error ranges from 2.86% ± 2.24% to 3.03% ± 2.40%. The test of noise degraded images (SNRs range from 16 to 20 dB) shows the unsigned error ranging from 2.63% ± 2.06% to 3.12% ± 2.11%. The test of raw images has an unsigned error 2.56% ± 2.10% compared to the manual tracings. Conclusions We have proposed an automated system which is able to detect carotid artery cross sectional boundary in MRI sequences during heart cycles. The accuracy reaches 2.56% ± 2.10% compared to the manual tracings. The system is stable, reliable and results are reproducible. PMID:21477378

  7. Cardiac Imaging for Ischemia in Asymptomatic Patients: Use of Coronary Artery Calcium Scanning to Improve Patient Selection: Lessons from the EISNER Study

    Microsoft Academic Search

    Alan Rozanski; Heidi Gransar; Nathan D. Wong; Leslee J. Shaw; Michael J. Zellweger; Daniel S. Berman

    \\u000a We review emerging data that identify how coronary artery calcium (CAC) scanning can complement radionuclide cardiac stress\\u000a testing for ischemia in the work-up of patients with suspected coronary artery disease (CAD). First, among screening populations,\\u000a i.e., patients with low (<15%) Bayesian likelihood of CAD, stress imaging is characterized by a high false-positive test rate\\u000a for CAD prediction and inability to

  8. A no-reference quality assessment algorithm for JPEG2000-compressed images based on local sharpness

    NASA Astrophysics Data System (ADS)

    Vu, Phong V.; Chandler, Damon M.

    2013-01-01

    In this paper, we present a no-reference quality assessment algorithm for JPEG2000-compressed images called EDIQ (EDge-based Image Quality). The algorithm works based on the assumption that the quality of JPEG2000- compressed images can be evaluated by separately computing the quality of the edge/near-edge regions and the non-edge regions where no edges are present. EDIQ first separates the input image into edge/near-edge regions and non-edge regions by applying Canny edge detection and edge-pixel dilation. Our previous sharpness algorithm, FISH [Vu and Chandler, 2012], is used to generate a sharpness map. The part of the sharpness map corresponding to the non-edge regions is collapsed by using root mean square to yield the image quality index of the non-edge regions. The other part of the sharpness map, which corresponds to the edge/near-edge regions, is weighted by the local RMS contrast and the local slope of magnitude spectrum to yield an enhanced quality map, which is then collapsed into the quality index of the edge/near-edge regions. These two indices are combined by a geometric mean to yield a quality indicator of the input image. Testing on the JPEG2000-compressed subsets of four different image-quality databases demonstrate that EDIQ is competitive with other no-reference image quality algorithms on JPEG2000-compressed images.

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

    SciTech Connect

    Bargellini, Irene, E-mail: irenebargellini@hotmail.com; Turini, Francesca; Bozzi, Elena; Lauretti, Dario; Cicorelli, Antonio; Lunardi, Alessandro; Cioni, Roberto; Bartolozzi, Carlo [University of Pisa, Department of Diagnostic and Interventional Radiology (Italy)] [University of Pisa, Department of Diagnostic and Interventional Radiology (Italy)

    2013-04-15

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

  10. Value of thallium-201 reinjection after delayed SPECT imaging for predicting reversible ischemia after coronary artery bypass grafting

    SciTech Connect

    Ohtani, H.; Tamaki, N.; Yonekura, Y.; Mohiuddin, I.H.; Hirata, K.; Ban, T.; Konishi, J. (Kyoto Univ. Faculty of Medicine (Japan))

    1990-08-15

    The reinjection of a small dose (40 MBq) of thallium-201 after stress and delayed imaging often shows new redistribution in the regions with persistent defect. To assess whether these segments may represent reversible ischemia, reinjection thallium-201 single-photon emission computed tomography (SPECT) was performed after stress and 3-hour delayed imaging in 24 patients before coronary artery bypass grafting (CABG). The left ventricular myocardium was divided into 5 myocardial segments and regional wall motion was scored on a scale from 0 (normal) to 4 (dyskinesia). Thallium-201 findings were compared with improvement in regional perfusion and wall motion 1 to 2 months after CABG. The reinjection imaging identified new redistribution in 15 of 32 persistent defects (47%) on the 3-hour delayed images. In the study of stress and delayed SPECT imaging, the improvement in perfusion was observed in 34 of 43 segments (79%) exhibiting redistribution and 15 of 32 (47%) segments without redistribution (p less than 0.01). The reinjection SPECT identified new redistribution in 12 of the 15 improved segments that were not detected on the delayed images. Similarly, the improvement in wall motion was observed in 23 of 31 segments (74%) exhibiting redistribution and 14 of 30 segments (47%) without redistribution on the delayed images (p less than 0.05). The reinjection identified new redistribution in 10 of the 14 improved segments that were undetected on the delayed images. The predictive values for improvement in perfusion and wall motion by the reinjection imaging were significantly higher (92 and 89%) than those by the delayed imaging (69 and 62%, respectively, p less than 0.05 each).

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  12. Nonrigid motion compensation in B-mode and contrast enhanced ultrasound image sequences of the carotid artery

    NASA Astrophysics Data System (ADS)

    Carvalho, Diego D. B.; Akkus, Zeynettin; Bosch, Johan G.; van den Oord, Stijn C. H.; Niessen, Wiro J.; Klein, Stefan

    2014-03-01

    In this work, we investigate nonrigid motion compensation in simultaneously acquired (side-by-side) B-mode ultrasound (BMUS) and contrast enhanced ultrasound (CEUS) image sequences of the carotid artery. These images are acquired to study the presence of intraplaque neovascularization (IPN), which is a marker of plaque vulnerability. IPN quantification is visualized by performing the maximum intensity projection (MIP) on the CEUS image sequence over time. As carotid images contain considerable motion, accurate global nonrigid motion compensation (GNMC) is required prior to the MIP. Moreover, we demonstrate that an improved lumen and plaque differentiation can be obtained by averaging the motion compensated BMUS images over time. We propose to use a previously published 2D+t nonrigid registration method, which is based on minimization of pixel intensity variance over time, using a spatially and temporally smooth B-spline deformation model. The validation compares displacements of plaque points with manual trackings by 3 experts in 11 carotids. The average (+/- standard deviation) root mean square error (RMSE) was 99+/-74?m for longitudinal and 47+/-18?m for radial displacements. These results were comparable with the interobserver variability, and with results of a local rigid registration technique based on speckle tracking, which estimates motion in a single point, whereas our approach applies motion compensation to the entire image. In conclusion, we evaluated that the GNMC technique produces reliable results. Since this technique tracks global deformations, it can aid in the quantification of IPN and the delineation of lumen and plaque contours.

  13. Image Quality and Radiation Dose of Lower Extremity CT Angiography Using 70 kVp, High Pitch Acquisition and Sinogram-Affirmed Iterative Reconstruction

    PubMed Central

    Qi, Li; Meinel, Felix G.; Zhou, Chang Sheng; Zhao, Yan E.; Schoepf, U. Joseph; Zhang, Long Jiang; Lu, Guang Ming

    2014-01-01

    Objectives The purpose of this study was to assess image quality and radiation dose of lower extremity CT angiography (CTA) with 70 kVp, high pitch acquisition and sinogram-affirmed iterative reconstruction (SAFIRE). Methods Lower extremity CTAs were performed on 44 patients: 22 patients were examined using protocol A (120 kVp, pitch of 0.85 and 120 ml of contrast agent on a first-generation dual-source CT) (120 kVp group) and 22 patients were evaluated with protocol B (70 kVp, pitch of 2.2 and 80 ml of contrast agent on a second-generation dual-source CT) (70 kVp group). Images from the 120 kVp group were reconstructed with filtered back projection (FBP) and images from the 70 kVp group with SAFIRE. The attenuation, image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Two radiologists subjectively assessed image quality of lower extremity arteries, plantar arterial enhancement and venous contamination of all patients. Radiation dose was compared between the two groups. Results Higher mean intravascular attenuation was obtained in the 70 kVp group (70 vs. 120 kVp group, 555.4±83.4 HU vs. 300.9±81.4 HU, P<0.001), as well as image noise (20.0±2.8 HU vs. 17.5±3.2 HU, P?=?0.010), SNR (32.0±7.0 vs. 19.1±6.9, P<0.001) and CNR (28.1±6.6 vs 15.9±6.3, P<0.001). No difference in subjective image quality and plantar arterial enhancement was found between 120 kVp group and 70 kVp group (all P>0.05). The venous contamination score was 1.5±0.8 for 120 kVp group while no venous contamination was found in 70 kVp group. The inter-observer agreement was moderate to good for both groups (0.515?1, P<0.001). The effective dose was lower in 70 kVp group (0.3±0.1 mSv) than in 120 kVp group (1.6±0.7 mSv)(P<0.001). Conclusions Lower extremity CTA using 70 kVp, high pitch acquisition and SAFIRE, except increasing imaging noise, allows for lower radiation dose and contrast material volume without compromising image quality. PMID:24915439

  14. Mutual information as a measure of image quality for 3D dynamic lung imaging with EIT.

    PubMed

    Crabb, M G; Davidson, J L; Little, R; Wright, P; Morgan, A R; Miller, C A; Naish, J H; Parker, G J M; Kikinis, R; McCann, H; Lionheart, W R B

    2014-05-01

    We report on a pilot study of dynamic lung electrical impedance tomography (EIT) at the University of Manchester. Low-noise EIT data at 100 frames per second were obtained from healthy male subjects during controlled breathing, followed by magnetic resonance imaging (MRI) subsequently used for spatial validation of the EIT reconstruction. The torso surface in the MR image and electrode positions obtained using MRI fiducial markers informed the construction of a 3D finite element model extruded along the caudal-distal axis of the subject. Small changes in the boundary that occur during respiration were accounted for by incorporating the sensitivity with respect to boundary shape into a robust temporal difference reconstruction algorithm. EIT and MRI images were co-registered using the open source medical imaging software, 3D Slicer. A quantitative comparison of quality of different EIT reconstructions was achieved through calculation of the mutual information with a lung-segmented MR image. EIT reconstructions using a linear shape correction algorithm reduced boundary image artefacts, yielding better contrast of the lungs, and had 10% greater mutual information compared with a standard linear EIT reconstruction. PMID:24710978

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

    PubMed Central

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

    2013-01-01

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

  16. Full-reference quality estimation for images with different spatial resolutions.

    PubMed

    Demirtas, Ali Murat; Reibman, Amy R; Jafarkhani, Hamid

    2014-05-01

    Multimedia communication is becoming pervasive because of the progress in wireless communications and multimedia coding. Estimating the quality of the visual content accurately is crucial in providing satisfactory service. State of the art visual quality assessment approaches are effective when the input image and reference image have the same resolution. However, finding the quality of an image that has spatial resolution different than that of the reference image is still a challenging problem. To solve this problem, we develop a quality estimator (QE), which computes the quality of the input image without resampling the reference or the input images. In this paper, we begin by identifying the potential weaknesses of previous approaches used to estimate the quality of experience. Next, we design a QE to estimate the quality of a distorted image with a lower resolution compared with the reference image. We also propose a subjective test environment to explore the success of the proposed algorithm in comparison with other QEs. When the input and test images have different resolutions, the subjective tests demonstrate that in most cases the proposed method works better than other approaches. In addition, the proposed algorithm also performs well when the reference image and the test image have the same resolution. PMID:24686279

  17. Nonconvulsive Partial Status Epilepticus Mimicking Recurrent Infarction Revealed by Diffusion-weighted and Arterial Spin Labeling Perfusion Magnetic Resonance Images.

    PubMed

    Kanazawa, Yuka; Morioka, Takato; Arakawa, Shuji; Furuta, Yoshihiko; Nakanishi, Asako; Kitazono, Takanari

    2015-04-01

    "Non-convulsive" partial status epilepticus (SE) is an important pathologic condition that should be differentiated from cerebral infarction. Herein, we reported 2 patients who had partial SE associated with old infarction in the right parietal lobe. Each patient had 2 episodes of left hemiparesis and hemisensory disturbance without convulsion. On diffusion-weighted magnetic resonance images (DW-MRI), a hyperintense lesion was noted in the cortex around the old infarction lesion, and recurrent infarction was suspected. Although electroencephalography (EEG) failed to reveal ictal discharges or interictal paroxysmal activities in 3 of 4 episodes, perfusion images with arterial spin labeling (ASL) clearly demonstrated ictal hyperperfusion in the area corresponding to the cortical hyperintense lesion on DW-MRI. After appropriate anticonvulsant treatment based on the diagnosis of partial SE, clinical symptoms were completely improved. These data stress the importance of cortical hyperintensity on DW-MRI and ictal ASL hyperperfusion, even when SE cannot be determined from EEG. PMID:25724245

  18. The image quality of ion computed tomography at clinical imaging dose levels

    SciTech Connect

    Hansen, David C., E-mail: dch@oncology.au.dk [Department of Experimental Clinical Oncology, Aarhus University Hospital, 8000 Aarhus (Denmark); Bassler, Niels [Department of Physics and Astronomy, Aarhus University, 8000 Aarhus (Denmark); Sørensen, Thomas Sangild [Department of Computer Science, Aarhus University, 8000 Aarhus, Denmark and Department of Clinical Medicine, Aarhus University, 8000 Aarhus (Denmark); Seco, Joao [Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School,Boston, Massachusetts 02114 (United States)

    2014-11-01

    Purpose: Accurately predicting the range of radiotherapy ions in vivo is important for the precise delivery of dose in particle therapy. Range uncertainty is currently the single largest contribution to the dose margins used in planning and leads to a higher dose to normal tissue. The use of ion CT has been proposed as a method to improve the range uncertainty and thereby reduce dose to normal tissue of the patient. A wide variety of ions have been proposed and studied for this purpose, but no studies evaluate the image quality obtained with different ions in a consistent manner. However, imaging doses ion CT is a concern which may limit the obtainable image quality. In addition, the imaging doses reported have not been directly comparable with x-ray CT doses due to the different biological impacts of ion radiation. The purpose of this work is to develop a robust methodology for comparing the image quality of ion CT with respect to particle therapy, taking into account different reconstruction methods and ion species. Methods: A comparison of different ions and energies was made. Ion CT projections were simulated for five different scenarios: Protons at 230 and 330 MeV, helium ions at 230 MeV/u, and carbon ions at 430 MeV/u. Maps of the water equivalent stopping power were reconstructed using a weighted least squares method. The dose was evaluated via a quality factor weighted CT dose index called the CT dose equivalent index (CTDEI). Spatial resolution was measured by the modulation transfer function. This was done by a noise-robust fit to the edge spread function. Second, the image quality as a function of the number of scanning angles was evaluated for protons at 230 MeV. In the resolution study, the CTDEI was fixed to 10 mSv, similar to a typical x-ray CT scan. Finally, scans at a range of CTDEI’s were done, to evaluate dose influence on reconstruction error. Results: All ions yielded accurate stopping power estimates, none of which were statistically different from the ground truth image. Resolution (as defined by the modulation transfer function = 10% point) was the best for the helium ions (18.21 line pairs/cm) and worst for the lower energy protons (9.37 line pairs/cm). The weighted quality factor for the different ions ranged from 1.23 for helium to 2.35 for carbon ions. For the angle study, a sharp increase in absolute error was observed below 45 distinct angles, giving the impression of a threshold, rather than smooth, limit to the number of angles. Conclusions: The method presented for comparing various ion CT modalities is feasible for practical use. While all studied ions would improve upon x-ray CT for particle range estimation, helium appears to give the best results and deserves further study for imaging.

  19. Imaging-based logics for ornamental stone quality chart definition

    NASA Astrophysics Data System (ADS)

    Bonifazi, Giuseppe; Gargiulo, Aldo; Serranti, Silvia; Raspi, Costantino

    2007-02-01

    Ornamental stone products are commercially classified on the market according to several factors related both to intrinsic lythologic characteristics and to their visible pictorial attributes. Sometimes these latter aspects prevail in quality criteria definition and assessment. Pictorial attributes are in any case also influenced by the performed working actions and the utilized tools selected to realize the final stone manufactured product. Stone surface finishing is a critical task because it can contribute to enhance certain aesthetic features of the stone itself. The study was addressed to develop an innovative set of methodologies and techniques able to quantify the aesthetic quality level of stone products taking into account both the physical and the aesthetical characteristics of the stones. In particular, the degree of polishing of the stone surfaces and the presence of defects have been evaluated, applying digital image processing strategies. Morphological and color parameters have been extracted developing specific software architectures. Results showed as the proposed approaches allow to quantify the degree of polishing and to identify surface defects related to the intrinsic characteristics of the stone and/or the performed working actions.

  20. Measurement of regional pulse-wave velocity using spatial compound imaging of the common carotid artery in vivo.

    PubMed

    Nagaoka, Ryo; Masuno, Genta; Kobayashi, Kazuto; Yoshizawa, Shin; Umemura, Shin-ichiro; Saijo, Yoshifumi

    2015-01-01

    Pulse-wave velocity (PWV) is an important index for diagnosing cardiovascular diseases. The pulse wave is volumetric change induced by heartbeat or inflowing blood, and significantly depends on the propagating path and stiffness of the artery. In this study, PWV of the propagating wave was visualized using spatial compound imaging with high temporal resolution. The frame rate was 1000 Hz, or a time interval of 1 ms. Subjects were four young healthy males and one young healthy female (n=5, age: 23.8±1.17 years old), and the measurement area was the right common carotid artery. PWVs in four phases (the four phases of heart valve opening and closing) were investigated during a cardiac cycle. In phase I, the heart pulsates. In phase II, the tricuspid and mitral valves close, and the aortic and pulmonic valves open. In phase III, the tricuspid and mitral valves open, and the aortic and pulmonic valves close. In phase IV, the propagating wave is reflected. PWVs in phases II and III were easily observed. PWVs were 3.52±1.11 m/s in phase I, 5.62±0.30 m/s in phase II, 7.94±0.85 m/s in phase III, and -4.60±0.99 m/s for the reflective wave. PWV was measured using Spatial Compound Imaging with high temporal resolution, and the PWV in each phase may be used as the index for diagnosing stages of arteriosclerosis progression. PMID:25152379

  1. Determination of the variation of the intima-media thickness and the diameter of arteries from echocardiographic ultrasound image sequences

    NASA Astrophysics Data System (ADS)

    dos Santos, Diego F.; Gutierrez, Marco A.; Costa, Eduardo T.

    2010-01-01

    The intima-media thickness (IMT) of the arteries serves as a marker of generalized atherosclerosis and several studies have shown a positive association between IMT and incident stroke. Several software systems have been developed to detect IMT and artery diameter, with some trying to obtain and show these values automatically without success because the operator normally has to do some later adjustments. Our proposed method shows that a totally automatic measurement is possible. This method is part (plugin) of a software called EchoLab that aims to be a repository of algorithms and methods used in echocardiography. We have tested the software with a set of images of a home-made phantom and our results show that it accurately measured the inner diameter of the silicone tube of the phantom (error less than 5%). We have also tested the software with real echocardiographic images and show the results for a set of 244 frames. Specialists at INCOR/USP are now validating the software.

  2. The pacing stress test: thallium-201 myocardial imaging after atrial pacing. Diagnostic value in detecting coronary artery disease compared with exercise testing

    SciTech Connect

    Heller, G.V.; Aroesty, J.M.; Parker, J.A.; McKay, R.G.; Silverman, K.J.; Als, A.V.; Come, P.C.; Kolodny, G.M.; Grossman, W.

    1984-05-01

    Many patients suspected of having coronary artery disease are unable to undergo adequate exercise testing. An alternate stress, pacing tachycardia, has been shown to produce electrocardiographic changes that are as sensitive and specific as those observed during exercise testing. To compare thallium-201 imaging after atrial pacing stress with thallium imaging after exercise stress, 22 patients undergoing cardiac catheterization were studied with both standard exercise thallium imaging and pacing thallium imaging. Positive ischemic electrocardiographic changes (greater than 1 mm ST segment depression) were noted in 11 of 16 patients with coronary artery disease during exercise, and in 15 of the 16 patients during atrial pacing. One of six patients with normal or trivial coronary artery disease had a positive electrocardiogram with each test. Exercise thallium imaging was positive in 13 of 16 patients with coronary artery disease compared with 15 of 16 patients during atrial pacing. Three of six patients without coronary artery disease had a positive scan with exercise testing, and two of these same patients developed a positive scan with atrial pacing. Of those patients with coronary artery disease and an abnormal scan, 85% showed redistribution with exercise testing compared with 87% during atrial pacing. Segment by segment comparison of thallium imaging after either atrial pacing or exercise showed that there was a good correlation of the location and severity of the thallium defects (r . 0.83, p . 0.0001, Spearman rank correlation). It is concluded that the location and presence of both fixed and transient thallium defects after atrial pacing are closely correlated with the findings after exercise testing.

  3. Quality evaluation of ultrasound imaging using a MATLAB test-bench

    NASA Astrophysics Data System (ADS)

    Zhao, Xin; Zhou, Jun; Loke, Wing-Fai; Chirala, Mohan; Zhang, Charlie

    2013-03-01

    The goal of this paper is to investigate and evaluate image quality, based on quality metrics and visual perception in ultrasound imaging under different imaging conditions. We first generate and simulate Bmode ultrasound images of various objects, using Field-II simulation toolbox [1]. Then we implement and embed front-end functional modules, mid-end functions including beamforming, receive beamforming, envelop detection and log compression, and back-end image processing methods (filtering and image enhancement techniques). Ultrasound images are evaluated as pairs using various image quality evaluation metrics and visual perception evaluation. The experimental results of this study show that: (1) better image quality is significantly obtained using over-sampling and signal emphasizing (high-signal level); (2) normalized images with speckle filters are rated better in terms of index-quality; and (3) enhanced images show better visual perception on all simulation datasets. This paper shows the utility of our MATLAB test-bench favoring simulated image quality and further demonstrates that the evaluation design is an important pre-processing step especially for the hardware design of ultrasound system.

  4. Optical imaging of steady flow in a phantom model of iliac artery stenosis: comparison of CFD simulations with PIV measurements

    NASA Astrophysics Data System (ADS)

    Shakeri, Mostafa; Khodarahmi, Iman; Sharp, M. Keith; Amini, Amir A.

    2010-03-01

    A flexible flow phantom system was designed and fabricated for the purpose of validation of i) CFD models proposed in conjunction with vascular imaging and ii) medical imaging techniques (such as MRI) that can produce flow velocities. In particular, one of the most challenging flows for both CFD models when modeling flow velocities and imaging techniques when measuring flow velocities are stenotic flows. Particle Image Velocimetry (PIV) is an optical technique for accurate measurement of in-vitro flow velocities and visualization of fluid flow. The fluid is seeded with tracer particles and the motion of the particles, illuminated with a laser light sheet, reveal particle velocities. Particle Image Velocimetry (PIV) was used to measure the flow fields across a Gaussian-shaped 90% area stenosis phantom. The flow parameters were adjusted to the phantom geometry to mimic the blood flow through the human common iliac artery. In addition, Computational Fluid Dynamics (CFD) simulation of the same flow was performed and the results were validated with those from PIV measurements. Steady flow rate of 46.9 ml/s was used, which corresponds to a Reynolds number of 188 and 595 at the inlet and stenosis throat, respectively. A maximum discrepancy of 15% in peak velocity was observed between the two techniques.

  5. Development of Software to Model AXAF-I Image Quality

    NASA Technical Reports Server (NTRS)

    Ahmad, Anees; Hawkins, Lamar

    1996-01-01

    This draft final report describes the work performed under the delivery order number 145 from May 1995 through August 1996. The scope of work included a number of software development tasks for the performance modeling of AXAF-I. A number of new capabilities and functions have been added to the GT software, which is the command mode version of the GRAZTRACE software, originally developed by MSFC. A structural data interface has been developed for the EAL (old SPAR) finite element analysis FEA program, which is being used by MSFC Structural Analysis group for the analysis of AXAF-I. This interface utility can read the structural deformation file from the EAL and other finite element analysis programs such as NASTRAN and COSMOS/M, and convert the data to a suitable format that can be used for the deformation ray-tracing to predict the image quality for a distorted mirror. There is a provision in this utility to expand the data from finite element models assuming 180 degrees symmetry. This utility has been used to predict image characteristics for the AXAF-I HRMA, when subjected to gravity effects in the horizontal x-ray ground test configuration. The development of the metrology data processing interface software has also been completed. It can read the HDOS FITS format surface map files, manipulate and filter the metrology data, and produce a deformation file, which can be used by GT for ray tracing for the mirror surface figure errors. This utility has been used to determine the optimum alignment (axial spacing and clocking) for the four pairs of AXAF-I mirrors. Based on this optimized alignment, the geometric images and effective focal lengths for the as built mirrors were predicted to cross check the results obtained by Kodak.

  6. Oral sildenafil therapy improves health-related quality of life and functional status in pulmonary arterial hypertension.

    PubMed

    Wong, Raymond Ching-Chiew; Koh, Geok Mui; Choong, Poh Hoon; Yip, Wei Luen James

    2007-07-31

    Sildenafil, a selective inhibitor of cyclic guanosine monophosphate (cGMP) specific phosphodiesterase-5 inhibitor, has shown promising results as a novel oral monotherapy in the treatment of pulmonary arterial hypertension (PAH). We conducted a cross-sectional survey of 19 consecutive PAH patients, aged 16-75 years, with WHO functional class II or worse over 3 months of oral sildenafil. Improvement in exercise capacity was achieved in 15/19 (79%) patients. 6-minute walk test distance increased from 299+/-118 m to 360+/-127 m, p=0.016, and WHO functional class decreased significantly. Both PASP and CI showed a non-significant trend toward improvement. Patients also reported significant improvement in physical (p=0.002) and social (p<0.001) functioning, and general health (p=0.01) of Rand SF-36 questionnaire. There was improvement in domains of role limitation due to physical health (p=0.16), emotion (p=0.14), and energy level (p=0.4). Our study suggests that oral sildenafil monotherapy is effective in improving exercise capacity and health-related quality of life amongst PAH patients. PMID:17064789

  7. A Multivariate Model for Coastal Water Quality Mapping Using Satellite Remote Sensing Images

    PubMed Central

    Su, Yuan-Fong; Liou, Jun-Jih; Hou, Ju-Chen; Hung, Wei-Chun; Hsu, Shu-Mei; Lien, Yi-Ting; Su, Ming-Daw; Cheng, Ke-Sheng; Wang, Yeng-Fung

    2008-01-01

    This study demonstrates the feasibility of coastal water quality mapping using satellite remote sensing images. Water quality sampling campaigns were conducted over a coastal area in northern Taiwan for measurements of three water quality variables including Secchi disk depth, turbidity, and total suspended solids. SPOT satellite images nearly concurrent with the water quality sampling campaigns were also acquired. A spectral reflectance estimation scheme proposed in this study was applied to SPOT multispectral images for estimation of the sea surface reflectance. Two models, univariate and multivariate, for water quality estimation using the sea surface reflectance derived from SPOT images were established. The multivariate model takes into consideration the wavelength-dependent combined effect of individual seawater constituents on the sea surface reflectance and is superior over the univariate model. Finally, quantitative coastal water quality mapping was accomplished by substituting the pixel-specific spectral reflectance into the multivariate water quality estimation model.

  8. Development and application of the informational and communication technologies in quality standards of health care management for patients with arterial hypertension.

    PubMed

    Sm??anov, V; Smiianova, O; Tarasenko, S

    2014-01-01

    Mobile health technologies improve the quality of health care service. The information and communication technology is developed and applied to remind patients with arterial hypertension to follow medical recommendations. The feedback system from general practitioners was developed (the reminder system for patients sending the feedbacks). It helped to supervise follow-up patients online. Suggested system provides for forming the database for summarized analysis of online survey of the patients, who receive medical care at health care institution, to take managerial decisions concerning the improvements of medical services quality. Evaluation of efficiency of the applied technology assured that the number of patients, who checked regularly his/her arterial pressure, increased by 31.00%. The number of patients, who visited doctors for preventive purpose two or more times during given year, rose by 18.24%. The number of patients with target pressure grew by 24.51% and composed 38.55±4.26%. PMID:25214275

  9. Image quality evaluation of medical color and monochrome displays using an imaging colorimeter

    NASA Astrophysics Data System (ADS)

    Roehrig, Hans; Gu, Xiliang; Fan, Jiahua

    2012-10-01

    The purpose of this presentation is to demonstrate the means which permit examining the accuracy of Image Quality with respect to MTF (Modulation Transfer Function) and NPS (Noise Power Spectrum) of Color Displays and Monochrome Displays. Indications were in the past that color displays could affect the clinical performance of color displays negatively compared to monochrome displays. Now colorimeters like the PM-1423 are available which have higher sensitivity and color accuracy than the traditional cameras like CCD cameras. Reference (1) was not based on measurements made with a colorimeter. This paper focuses on the measurements of physical characteristics of the spatial resolution and noise performance of color and monochrome medical displays which were made with a colorimeter and we will after this meeting submit the data to an ROC study so we have again a paper to present at a future SPIE Conference.Specifically, Modulation Transfer Function (MTF) and Noise Power Spectrum (NPS) were evaluated and compared at different digital driving levels (DDL) between the two medical displays. This paper focuses on the measurements of physical characteristics of the spatial resolution and noise performance of color and monochrome medical displays which were made with a colorimeter and we will after this meeting submit the data to an ROC study so we have again a paper to present at a future Annual SPIE Conference. Specifically, Modulation Transfer Function (MTF) and Noise Power Spectrum (NPS) were evaluated and compared at different digital driving levels (DDL) between the two medical displays. The Imaging Colorimeter. Measurement of color image quality needs were done with an imaging colorimeter as it is shown below. Imaging colorimetry is ideally suited to FPD measurement because imaging systems capture spatial data generating millions of data points in a single measurement operation. The imaging colorimeter which was used was the PM-1423 from Radiant Imaging. It uses full-frame CCDs with 100% fill factor which makes it very suitable to measure luminance and chrominance of individual LCD pixels and sub-pixels on an LCD display. The CCDs used are 14-bit thermoelectrically cooled and temperature stabilized , scientific grade.

  10. Short term effects of exercise training on exercise capacity and quality of life in patients with pulmonary arterial hypertension: protocol for a randomised controlled trial

    Microsoft Academic Search

    Louise Ganderton; Sue Jenkins; Kevin Gain; Robin Fowler; Peta Winship; Dianne Lunt; Eli Gabbay

    2011-01-01

    Background  Advances in the understanding and management of pulmonary arterial hypertension have enabled earlier diagnosis and improved\\u000a prognosis. However, despite best available therapy, symptoms of exertional dyspnoea and fatigue are commonly reported and\\u000a result in a reduced capacity to perform daily activities and impaired quality of life. Exercise training has demonstrated\\u000a efficacy in individuals with other respiratory and cardiovascular diseases. Historically,

  11. Psychological and Quality-of-Life Outcomes from a Comprehensive Stress Reduction and Lifestyle Program in Patients with Coronary Artery Disease: Results of a Randomized Trial

    Microsoft Academic Search

    Andreas Michalsen; Paul Grossman; Nils Lehmann; Nicola T. M. Knoblauch; Anna Paul; Susanne Moebus; Thomas Budde; Gustav J. Dobos

    2005-01-01

    Background: Stress reduction and comprehensive lifestyle modification programs have improved atherosclerosis and cardiac risk factors in earlier trials. Little is known about the impact of such programs on quality-of-life (QoL) and psychological outcomes. Given recent significant improvements in cardiac care, we evaluated the current benefit of stress reduction\\/lifestyle modification on QoL and emotional distress in patients with coronary artery disease

  12. Quantification of radiographic image quality based on patient anatomical contrast-to-noise ratio: a preliminary study with chest images

    NASA Astrophysics Data System (ADS)

    Lin, Yuan; Wang, Xiaohui; Sehnert, William J.; Foos, David H.; Barski, Lori; Samei, Ehsan

    2010-02-01

    The quality of a digital radiograph for diagnostic imaging depends on many factors, such as the capture system DQE and MTF, the exposure technique factors, the patient anatomy, and the particular image processing method and processing parameters used. Therefore, the overall image quality as perceived by the radiologists depends on many factors. This work explores objective image quality metrics directly from display-ready patient images. A preliminary study was conducted based on a multi-frequency analysis of anatomy contrast and noise magnitude from 250 computed radiography (CR) chest radiographs (150 PA, 50 AP captured with anti-scatter grids, and 50 AP without grids). The contrast and noise values were evaluated in different sub-bands separately according to their frequency properties. Contrast-Noise ratio (CNR) was calculated, the results correlated well with the human observers' overall impression on the images captured with and without grids.

  13. The influence of patient thickness and imaging system on patient dose and physical image quality in digital chest imaging.

    PubMed

    Ullman, Gustaf; Sandborg, Michael; Dance, David R; Hunt, Roger; Alm Carlsson, Gudrun

    2005-01-01

    The aim of this work was to study the influence of patient thickness, tube voltage and image detector on patient dose, contrast and ideal observer signal-to-noise ratio (SNR(I)), for pathological details positioned at different regions in the image in posterior-anterior (PA) chest radiology. A Monte Carlo computational model was used to compute measures of physical image quality (contrast, SNR(I)) and patient effective dose, E. Two metastasis-like details positioned in the central right lung and right lung near the spine, respectively, were studied. The tube voltage was varied between 100 and 150 kV and the patient thickness between 20 and 28 cm. Both, a computed radiography (CR) system and a direct radiography (DR) system, were investigated. The DR system provides both lower doses and better image quality compared with the CR system. The SNR(I)2/E is approximately 2.9 times higher for the DR system compared with the CR system. PMID:15933124

  14. Multimodality imaging and transcatheter coil embolization of an iatrogenic subclavian artery-internal jugular vein fistula.

    PubMed

    Cai, Qiangjun; Sickler, Cory; Christenson, Stuart; Dotani, Imran

    2015-01-01

    A 69-year-old man was found to have a loud continuous bruit in the neck. Duplex carotid ultrasound showed high-velocity turbulent flow in the dilated and pulsatile right internal jugular vein. Computed tomography angiogram demonstrated markedly enlarged right internal jugular vein with a posteriorly located arteriovenous communication. Invasive angiography revealed an arteriovenous fistula originating from the right subclavian artery draining into the dilated and tortuous right internal jugular vein. An endovascular coil was successfully deployed in the fistula tract. Subclavian artery-internal jugular vein fistula is rare. Our case is most likely iatrogenic towing to previous central venous cannulation during coronary bypass grafting. The anatomic challenge of this fistula, being located in the thoracic outlet, makes endovascular repair particularly favourable. PMID:25286164

  15. Imaging diagnosis--Arterial and venous thromboses of the proximal limb in two thoroughbred racehorses.

    PubMed

    Vaughan, Betsy; Whitcomb, Mary B; Puchalski, Sarah M; Poulin-Braim, Amy E; Nieto, Jorge E; Galuppo, Larry D

    2010-01-01

    Thromboses of the cranial tibial vein (Horse 1) and brachial, median, and cranial circumflex humeral arteries (Horse 2) were identified as causes of unilateral lameness in two Thoroughbred racehorses. Nuclear scintigraphy was performed for suspicion of long bone stress fractures but instead allowed identification of unusual areas of increased radiopharmaceutical uptake within soft tissues of the affected limbs. Ultrasonography of these regions allowed identification of occlusive thrombi within a 25 cm length of the cranial tibial vein (Horse 1) and variable lengths of affected arteries in Horse 2. Horse 1 developed secondary infections and was euthanized. Staphylococcus aureus was isolated from all sites. The cause of thrombosis was not identified in Horse 2. PMID:20469553

  16. Tomographic particle image velocimetry investigation of the flow in a modeled human carotid artery bifurcation

    Microsoft Academic Search

    N. A. Buchmann; C. Atkinson; M. C. Jeremy; J. Soria

    2011-01-01

    Hemodynamic forces within the human carotid artery are well known to play a key role in the initiation and progression of\\u000a vascular diseases such as atherosclerosis. The degree and extent of the disease largely depends on the prevailing three-dimensional\\u000a flow structure and wall shear stress (WSS) distribution. This work presents tomographic PIV (Tomo-PIV) measurements of the\\u000a flow structure and WSS

  17. Pediatric surgical image. A rare case: celiac artery compression syndrome in an asymptomatic child.

    PubMed

    Alehan, Dursun; Dogan, Omer Faruk

    2004-04-01

    Celiac artery compression syndrome is a rare disorder and characterized by postprandial intestinal angina caused by insufficient blood supply to the gastrointestinal organs in symptomatic patients. This pathology is also known as median arcuate syndrome. The authors report a case of 12-year-old boy with severe celiac artery compression by the median arcuate ligament that was diagnosed by Magnetic Resonance Angiography (MRA) and color dupplex ultrasonography (US). There was only a bruit in the upper midepigastrium, and there were no gastrointestinal symptoms despite severe compression of celiac trunk. This clinicopathologic entity is very rare but represents severe complaints and clinical results caused by a decreased rate of the intestinal blood flow. In this report the authors suggest that the diagnosis of celiac artery compression should be considered in asymptomatic pediatric patients representing abdominal bruit or with palpated thrill in the upper epigastrium. In comparison with case reports present in the English-language literature, the patient reported on here is the youngest diagnosed. PMID:15065050

  18. Combined anatomical and functional imaging using coronary CT angiography and myocardial perfusion SPECT in symptomatic adults with abnormal origin of a coronary artery.

    PubMed

    Uebleis, C; Groebner, M; von Ziegler, F; Becker, A; Rischpler, C; Tegtmeyer, R; Becker, C; Lehner, S; Haug, A R; Cumming, P; Bartenstein, P; Franz, W M; Hacker, M

    2012-10-01

    There has been a lack of standardized workup guidelines for patients with congenital abnormal origin of a coronary artery from the opposite sinus (ACAOS). We aimed to evaluate the use of cardiac hybrid imaging using multi-detector row CT (MDCT) for coronary CT angiography (Coronary CTA) and stress-rest myocardial perfusion SPECT (MPS) for comprehensive diagnosis of symptomatic adult patients with ACAOS. Seventeen symptomatic patients (12 men; 54 ± 13 years) presenting with ACAOS underwent coronary CTA and MPS. Imaging data were analyzed by conventional means, and with additional use of 3D image fusion to allocate stress induced perfusion defects (PD) to their supplying coronary arteries. An anomalous RCA arose from the left anterior sinus in eight patients, an abnormal origin from the right sinus was detected in nine patients (5 left coronary arteries, LCA and 4 LCx). Five of the 17 patients (29%) demonstrated a reversible PD in MPS. There was no correlation between the anatomical variants of ACAOS and the presence of myocardial ischemia. Image fusion enabled the allocation of reversible PD to the anomalous vessel in three patients (two cases in the RCA and the other in the LCA territory); PD in two patients were allocated to the territory of artery giving rise to the anomalies, rather than the anomalies themselves. In a small cohort of adult symptomatic patients with ACAOS anomaly there was no relation found between the specific anatomical variant and the appearance of stress induced myocardial ischemia using cardiac hybrid imaging. PMID:22147107

  19. Development and measurement of the goodness of test images for visual print quality evaluation

    Microsoft Academic Search

    Raisa Halonen; Mikko Nuutinen; Reijo Asikainen; Pirkko Oittinen

    2010-01-01

    The aim of the study was to develop a test image for print quality evaluation to improve the current state of the art in testing the quality of digital printing. The image presented by the authors in EI09 portrayed a breakfast scene, the content of which could roughly be divided in four object categories: a woman, a table with objects,

  20. Presence and video games: The impact of image quality and skill level

    Microsoft Academic Search

    Cheryl Campanella Bracken

    Abstract This study investigates the impact of image quality and skill level on presence-related reactions to video games. Past research has demonstrated positive associations between image quality and presence and video game technology and presence. No study to date, however, has examined the presence effects of video games played in enhanced or high definition. This paper reports the results of

  1. Presence and video games: The impact of image quality and skill level

    Microsoft Academic Search

    Cheryl Campanella Bracken Paul

    This study investigates the impact of image quality and skill level on presence-related reactions to video games. Past research has demonstrated positive associations between image quality and presence and video game technology and presence. No study to date, however, has examined the presence effects of video games played in enhanced or high definition. This paper reports the results of two

  2. Uneven Background Extraction And Segmentation Of Good, Normal And Bad Quality Fingerprint Images

    Microsoft Academic Search

    S. S. Jambhorkar; S. S. Gornale; V. T. Humbe; R. R. Manza; K. V. Kale

    2006-01-01

    In this paper, we have considered a problem of uneven background extraction and segmentation of good, normal and bad quality fingerprint images, though we propose an algorithm based on morphological transformations. Our result shows that the proposed algorithm can successfully extract the background of good, normal and bad quality images of fingerprint and well segment the foreground area. The algorithm

  3. Analysis of Image Quality After Correction Using the T.H.E.M.I.S. Image Stabilizer Optical System

    NASA Astrophysics Data System (ADS)

    Molodij, G.; Rayrole, J.

    We present the results of numerical simulations to analyze the effects of anisoplanatism on T.H.E.M.I.S. adaptive optics system when observing extended sources. We compute analytically the long exposure optical tranfer functions in the field-of-view to simulate the image quality after correction using adaptive optics systems. We demonstrate the capacity of the image stabilizer optical system for very large field-of-view observations with medium image qual ity while the capacity of high order adaptive optics system is suitable for high image quality observations but to the price of a reduction of the field-of-view .

  4. Quantitative spatial comparison of diffuse optical imaging with blood oxygen level-dependent and arterial spin labeling-based functional magnetic resonance imaging

    PubMed Central

    Huppert, Theodore J.; Hoge, Rick D.; Dale, Anders M.; Franceschini, Maria A.; Boas, David A.

    2009-01-01

    Akin to functional magnetic resonance imaging (fMRI), diffuse optical imaging (DOI) is a noninvasive method for measuring localized changes in hemoglobin levels within the brain. When combined with fMRI methods, multimodality approaches could offer an integrated perspective on the biophysics, anatomy, and physiology underlying each of the imaging modalities. Vital to the correct interpretation of such studies, control experiments to test the consistency of both modalities must be performed. Here, we compare DOI with blood oxygen level-dependent (BOLD) and arterial spin labeling fMRI-based methods in order to explore the spatial agreement of the response amplitudes recorded by these two methods. Rather than creating optical images by regularized, tomographic reconstructions, we project the fMRI image into optical measurement space using the optical forward problem. We report statistically better spatial correlation between the fMRI-BOLD response and the optically measured deoxyhemoglobin (R=0.71, p=1 × 10?7) than between the BOLD and oxyhemoglobin or total hemoglobin measures (R=0.38, p=0.04|0.37, p=0.05, respectively). Similarly, we find that the correlation between the ASL measured blood flow and optically measured total and oxyhemoglobin is stronger (R=0.73, p=5 × 10?6 and R=0.71, p=9 × 10?6, respectively) than the flow to deoxyhemoglobin spatial correlation (R=0.26, p=0.10). PMID:17212541

  5. Imaging Geostationary Satellites with a Common-Mount Interferometer: Image Quality and Fringe Tracking

    NASA Astrophysics Data System (ADS)

    Jorgensen, A.; Schmitt, H.; Mozurkewich, D.; Armstrong, J. T.; Hindsley, R. B.; Baines, E. K.

    2012-09-01

    Imaging geostationary satellites is difficult because they are both too large and too small. They are too small to resolve with existing ground-based single telescopes, and they are too large (and too faint) to resolve with existing ground-based interferometers. Earth-rotation synthesis also does not work with geostationary satellites. We have designed a common-mount telescopes which we believe is the right instrument for geostationary satellite imaging, and described it previously in a number of publications (e.g. AMOS papers Mozurkewich et al. 2011, Jorgensen et al. 2011, Schmitt et al. 2011, and others). In this paper we will provide an overview of the instrument and explore its capabilities in more detail, using a typical geostationary satellite as an example. Specifically we will look at the fringe-tracking capability which is required for phase measurement and thus imaging. We will also look at the required integration time and its relationship to fringe-tracking capability and image quality.

  6. Which histological characteristics of basal cell carcinomas influence the quality of optical coherence tomography imaging?

    NASA Astrophysics Data System (ADS)

    Mogensen, M.; Thrane, L.; Joergensen, T. M.; Nürnberg, B. M.; Jemec, G. B. E.

    2009-07-01

    We explore how histopathology parameters influence OCT imaging of basal cell carcinomas (BCC) and address whether such parameters correlate with the quality of the recorded OCT images. Our results indicate that inflammation impairs OCT imaging and that sun-damaged skin can sometimes provide more clear-cut images of skin cancer lesions using OCT imaging when compared to skin cancer surrounded by skin without sun-damage.

  7. Digital mammography--DQE versus optimized image quality in clinical environment: an on site study

    NASA Astrophysics Data System (ADS)

    Oberhofer, Nadia; Fracchetti, Alessandro; Springeth, Margareth; Moroder, Ehrenfried

    2010-04-01

    The intrinsic quality of the detection system of 7 different digital mammography units (5 direct radiography DR; 2 computed radiography CR), expressed by DQE, has been compared with their image quality/dose performances in clinical use. DQE measurements followed IEC 62220-1-2 using a tungsten test object for MTF determination. For image quality assessment two different methods have been applied: 1) measurement of contrast to noise ratio (CNR) according to the European guidelines and 2) contrast-detail (CD) evaluation. The latter was carried out with the phantom CDMAM ver. 3.4 and the commercial software CDMAM Analyser ver. 1.1 (both Artinis) for automated image analysis. The overall image quality index IQFinv proposed by the software has been validated. Correspondence between the two methods has been shown figuring out a linear correlation between CNR and IQFinv. All systems were optimized with respect to image quality and average glandular dose (AGD) within the constraints of automatic exposure control (AEC). For each equipment, a good image quality level was defined by means of CD analysis, and the corresponding CNR value considered as target value. The goal was to achieve for different PMMA-phantom thicknesses constant image quality, that means the CNR target value, at minimum dose. All DR systems exhibited higher DQE and significantly better image quality compared to CR systems. Generally switching, where available, to a target/filter combination with an x-ray spectrum of higher mean energy permitted dose savings at equal image quality. However, several systems did not allow to modify the AEC in order to apply optimal radiographic technique in clinical use. The best ratio image quality/dose was achieved by a unit with a-Se detector and W anode only recently available on the market.

  8. Coronary Arteries

    MedlinePLUS

    ... and animations for grades K-6. The Coronary Arteries | Share Coronary Circulation The heart muscle, like every ... into two main coronary blood vessels (also called arteries). These coronary arteries branch off into smaller arteries, ...

  9. A comprehensive study on the relationship between image quality and imaging dose in low-dose cone beam CT

    PubMed Central

    Yan, Hao; Cervino, Laura; Jia, Xun; Jiang, Steve B.

    2012-01-01

    While compressed sensing (CS) based algorithms have been developed for low-dose cone beam CT (CBCT) reconstruction, a clear understanding on the relationship between the image quality and imaging dose at low dose levels is needed. In this paper, we qualitatively investigate this subject in a comprehensive manner with extensive experimental and simulation studies. The basic idea is to plot both the image quality and imaging dose together as functions of number of projections and mAs per projection over the whole clinically relevant range. On this basis, a clear understanding on the tradeoff between image quality and imaging dose can be achieved and optimal low-dose CBCT scan protocols can be developed to maximize the dose reduction while minimizing the image quality loss for various imaging tasks in image guided radiation therapy (IGRT). Main findings of this work include: 1) Under the CS-based reconstruction framework, image quality has little degradation over a large range of dose variation. Image quality degradation becomes evident when the imaging dose (approximated with the x-ray tube load) is decreased below 100 total mAs. An imaging dose lower than 40 total mAs leads to a dramatic image degradation, and thus should be used cautiously. Optimal low-dose CBCT scan protocols likely fall in the dose range of 40–100 total mAs, depending on the specific IGRT applications. 2) Among different scan protocols at a constant low-dose level, the super sparse-view reconstruction with projection number less than 50 is the most challenging case, even with strong regularization. Better image quality can be acquired with low mAs protocols. 3) The optimal scan protocol is the combination of a medium number of projections and a medium level of mAs/view. This is more evident when the dose is around 72.8 total mAs or below and when the ROI is a low-contrast or high-resolution object. Based on our results, the optimal number of projections is around 90 to 120. 4) The clinically acceptable lowest imaging dose level is task dependent. In our study, 72.8mAs is a safe dose level for visualizing low-contrast objects, while 12.2 total mAs is sufficient for detecting high-contrast objects of diameter greater than 3 mm. PMID:22459913

  10. Comparison of Fusion Imaging Using a Combined SPECT/CT System and Intra-arterial CT: Assessment of Drug Distribution by an Implantable Port System in Patients Undergoing Hepatic Arterial Infusion Chemotherapy

    SciTech Connect

    Ikeda, Osamu, E-mail: osamu-3643ik@do9.enjoy.ne.jp; Kusunoki, Shinichiroh; Nakaura, Takeshi; Shiraishi, Shinya; Kawanaka, Kouichi; Tomiguchi, Seiji; Yamashita, Yasuyuki [Kumamoto University Graduate School of Medical and Pharmaceutical Sciences, Department of Diagnostic Radiology (Japan); Takamori, Hiroshi; Chikamoto, Akira; Kanemitsu, Keiichiro [Kumamoto University Graduate School of Medical and Pharmaceutical Sciences, Gastroenterological Surgery (Japan)

    2006-06-15

    Hepatic arterial infusion (HAI) chemotherapy is effective for treating primary and metastatic carcinoma of the liver. We compared the perfusion patterns of HAI chemotherapy on intra-arterial port-catheter computed tomography (iapc-CT) and fused images obtained with a combined single-photon emission computed tomography/computed tomography (SPECT/CT) system. We studied 28 patients with primary or metastatic carcinoma of the liver who bore an implantable HAI port system. All underwent abdominal SPECT using Tc-99m-MAA (185 Mbq); the injection rate was 1 mL/min, identical to the chemotherapy infusion rate, and 0.5 mL/sec for iapc-CT. Delivery was through an implantable port. We compared the intrahepatic perfusion (IHP) and extrahepatic perfusion (EHP) patterns of HAI chemotherapy on iapc-CT images and fused images obtained with a combined SPECT/CT system. In 23 of 28 patients (82%), IHP patterns on iapc-CT images and fused images were identical. In 5 of the 28 patients (18%), IHP on fusion images was different from IHP on iapc-CT images. EHP was seen on fused images in 12 of the 28 patients (43%) and on iapc-CT images in 8 patients (29%). In 17 patients (61%), upper gastrointestinal endoscopy revealed gastroduodenal mucosal lesions. EHP was revealed on fused images in 10 of these patients; 9 of them manifested gastroduodenal toxicity at the time of subsequent HAI chemotherapy. Fusion imaging using the combined SPECT/CT system reflects the actual distribution of the infused anticancer agent. This information is valuable not only for monitoring adequate drug distribution but also for avoiding potential extrahepatic complications.

  11. Towards Improving the NIST Fingerprint Image Quality (NFIQ) Algorithm (Extended Version)

    E-print Network

    Merkle, Johannes; Bausinger, Oliver; Breitenstein, Marco; Elwart, Kristina; Nuppeney, Markus

    2010-01-01

    The NIST Fingerprint Image Quality (NFIQ) algorithm has become a standard method to assess fingerprint image quality. However, in many applications a more accurate and reliable assessment is desirable. In this publication, we report on our efforts to optimize the NFIQ algorithm by a re-training of the underlying neural network based on a large fingerprint image database. Although we only achieved a marginal improvement, our work has revealed several areas for potential optimization.

  12. Exercise training for health-related quality of life in peripheral artery disease: A systematic review and meta-analysis.

    PubMed

    Parmenter, Belinda J; Dieberg, Gudrun; Phipps, Glenn; Smart, Neil A

    2015-02-01

    We sought to quantify whether health-related quality of life (HRQoL) is improved through exercise training in people with peripheral artery disease (PAD) and to clarify which prescriptions were optimal for improving HRQoL when compared to usual care. We conducted a systematic search (PubMed, CINAHL, Cochrane Central Register of Controlled Trials; 1966 - 31 August 2014). We only included randomized controlled trials (RCTs) of exercise training versus usual medical care in persons with PAD that included the Walking Impairment Questionnaire (WIQ) and Short-Form Health Survey component summary scores as outcomes. Of 15 RCTs, 1257 participants were studied: 543 participated in supervised exercise, with only 61 undertaking resistance training and 316 unsupervised exercise. When compared to controls, participants who completed any form of exercise training significantly improved their WIQ speed [mean difference (MD) 9.60 (95% CI 6.98 to 12.23, p<0.00001)]; WIQ distance [MD 7.41 (95% CI 4.49 to 10.33, p<0.00001)] and WIQ stair-climbing [MD 5.07 (95% CI 3.16 to 6.99, p<0.00001)]. Walking also significantly improved the Short-Form Physical Component Summary (SF-PCS) score when compared to controls [MD 1.24 (95% CI 0.48 to 2.01, p=0.001)], but not the Mental Component Summary (SF-MCS) score [MD -0.55 (95% CI -1.27 to 0.18, p=0.14)]. Exercise training improves the SF-PCS dimension, as well as perceived walking distance, speed and stair-climbing as measured by the WIQ, but not the SF-MCS score. Future studies should aim to blind assessors of such subjective measures, and study alternative modes and prescriptions of exercise alternative to walking. PMID:25432991

  13. High quality multi-focus image fusion using self-similarity and depth information

    NASA Astrophysics Data System (ADS)

    Guo, Di; Yan, Jingwen; Qu, Xiaobo

    2015-03-01

    Due to the limited depth of field in a camera, some imaging objects will be blurred if they are located far from the focus plane and the other objects on the plane will be clear. Multi-focus image fusion synthesizes a sharp image from multiple partially focused images. However, traditional fused images usually suffer from blurring effects and pixel distortions. In this paper, we explore two unique characteristics of multi-focus images: (1) The self-similarity of a single image and the shared similarity among multiple source images; (2) The distances from object to focal plane. The former characteristic is used to identify image structure-driven regions while the latter refine the image clarity by automatically estimating depth information of blurred images. Experimental results demonstrate that the proposed method outperforms the state-of-the-art fusion methods on image quality and objective fusion criteria.

  14. Incremental value of combined perfusion and function over perfusion alone by gated SPECT myocardial perfusion imaging for detection of severe three-vessel coronary artery disease

    Microsoft Academic Search

    Ronaldo S. L. Lima; Denny D. Watson; Allen R. Goode; Mir S. Siadaty; Michael Ragosta; George A. Beller; Habib Samady

    2003-01-01

    ObjectivesWe hypothesized that combining functional assessment to perfusion enhances the ability of electrocardiographic gating Tc-99m sestamibi single photon emission computed tomography (gated SPECT) myocardial perfusion imaging (MPI) to detect defects in multiple vascular territories in patients with severe three-vessel coronary artery disease (3VD).

  15. Recent Developments in Hyperspectral Imaging for Assessment of Food Quality and Safety

    PubMed Central

    Huang, Hui; Liu, Li; Ngadi, Michael O.

    2014-01-01

    Hyperspectral imaging which combines imaging and spectroscopic technology is rapidly gaining ground as a non-destructive, real-time detection tool for food quality and safety assessment. Hyperspectral imaging could be used to simultaneously obtain large amounts of spatial and spectral information on the objects being studied. This paper provides a comprehensive review on the recent development of hyperspectral imaging applications in food and food products. The potential and future work of hyperspectral imaging for food quality and safety control is also discussed. PMID:24759119

  16. Atherosclerotic renal artery stenosis

    Microsoft Academic Search

    Robert D. Safian

    2003-01-01

    Opinion statement  The clinical diagnosis of renal artery stenosis relies on a high index of suspicion and confirmation by noninvasive imaging\\u000a modalities. There are three distinct clinical syndromes associated with renal artery stenosis: renin-dependent hypertension,\\u000a essential hypertension, and ischemic nephropathy. Clinical features that should heighten suspicion for renal artery stenosis\\u000a include abrupt-onset or accelerated hypertension at any age, unexplained acute or

  17. Bipolar supernumerary renal artery

    Microsoft Academic Search

    Abolhassan B. Shakeri; R. Shane Tubbs; Mohammadali M. Shoja; Parham Pezeshk; Ramin M. Farahani; Amir A. Khaki; Fatemeh Ezzati; Farshad Seyednejad

    2007-01-01

    The variations of renal arteries are considered critical issues that surgeons should have thorough envision and appreciation\\u000a of the condition. Variations of these vessels may influences urological, renal transplantation and laparoscopic surgeries.\\u000a We present a case of bilateral accessory renal artery with a striking pre-hilar branching pattern encountered upon digital\\u000a subtraction angiography (DSA) for imaging of the renal arteries of

  18. Visible to SWIR hyperspectral imaging for produce safety and quality evaluation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hyperspectral imaging techniques, combining the advantages of spectroscopy and imaging, have found wider use in food quality and safety evaluation applications during the past decade. In light of the prevalent use of hyperspectral imaging techniques in the visible to near-infrared (VNIR: 400 -1000 n...

  19. Image-based biomechanical modeling of aortic wall stress and vessel deformation: response to pulsatile arterial pressure simulations

    NASA Astrophysics Data System (ADS)

    Hazer, Dilana; Bauer, Miriam; Unterhinninghofen, Roland; Dillmann, Rüdiger; Richter, Götz-M.

    2008-03-01

    Image-based modeling of cardiovascular biomechanics may be very helpful for patients with aortic aneurysms to predict the risk of rupture and evaluate the necessity of a surgical intervention. In order to generate a reliable support it is necessary to develop exact patient-specific models that simulate biomechanical parameters and provide individual structural analysis of the state of fatigue and characterize this to the potential of rupture of the aortic wall. The patient-specific geometry used here originates from a CT scan of an Abdominal Aortic Aneurysm (AAA). The computations are based on the Finite Element Method (FEM) and simulate the wall stress distribution and the vessel deformation. The wall transient boundary conditions are based on real time-dependent pressure simulations obtained from a previous computational fluid dynamics study. The physiological wall material properties consider a nonlinear hyperelastic constitutive model, based on realistic ex-vivo analysis of the aneurismal arterial tissue. The results showed complex deformation and stress distribution on the AAA wall. The maximum stresses occurred at the systole and are found around the aneurismal bulge in regions close to inflection points. Biomechanical modeling based on medical images and coupled with patient-specific hemodynamics allows analysing and quantifying the effects of dilatation of the arterial wall due to the pulsatile aortic pressure. It provides a physical and realistic insight into the wall mechanics and enables predictive simulations of AAA growth and assessment of rupture. Further development integrating endovascular models would help evaluating non-invasively individual treatment strategies for optimal placement and improved device design.

  20. A conceptual study of automatic and semi-automatic quality assurance techniques for round image processing

    NASA Technical Reports Server (NTRS)

    1983-01-01

    This report summarizes the results of a study conducted by Engineering and Economics Research (EER), Inc. under NASA Contract Number NAS5-27513. The study involved the development of preliminary concepts for automatic and semiautomatic quality assurance (QA) techniques for ground image processing. A distinction is made between quality assessment and the more comprehensive quality assurance which includes decision making and system feedback control in response to quality assessment.

  1. Effect of exercise level on the ability of thallium-201 tomographic imaging in detecting coronary artery disease: Analysis of 461 patients

    SciTech Connect

    Iskandrian, A.S.; Heo, J.; Kong, B.; Lyons, E. (Philadelphia Heart Institute, PA (USA))

    1989-11-15

    This study examined the effect of the level of exercise on the ability of thallium-201 imaging with single photon emission computed tomography (SPECT) to detect coronary artery disease. Patients in group 1 (n = 164) achieved adequate exercise end points, defined as positive exercise electrocardiograms or greater than or equal to 85% of maximal predicted heart rate. Patients in group 2 (n = 108) had submaximal exercise. The SPECT thallium-201 images showed perfusion defects in 74%, 88%, and 98%, respectively, of patients with one, two and three vessel coronary artery disease in group 1, compared with 52%, 84% and 79%, respectively, of such patients in group 2 (p less than 0.05). Perfusion defects showed partial or complete redistribution consistent with ischemia in 56%, 80% and 88%, respectively, of patients with one, two and three vessel coronary artery disease in group 1 compared with 35%, 58% and 56%, respectively, of such patients in group 2 (p = 0.08, less than 0.03 and less than 0.001, respectively). Of 58 patients with normal coronary angiograms or less than 50% diameter stenosis, 36 (62%) had normal SPECT images. In a separate group of 131 patients with less than 5% pretest probability of coronary artery disease, the specificity was 93%. The sensitivity of exercise SPECT imaging in group 1 was higher than that of ST segment depression (p less than 0.001). Thus, the level of exercise affects the results of SPECT thallium imaging in the localization and evaluation of the extent of coronary artery disease and the detection of ischemia.

  2. Image Comparison by Compound Disjoint Information with Applications to Perceptual Visual Quality Assessment, Image Registration and Tracking

    Microsoft Academic Search

    Zhaohui Sun; Anthony Hoogs

    2010-01-01

    In this paper, we study (normalized) disjoint information as a metric for image comparison and its applications to perceptual\\u000a image quality assessment, image registration, and video tracking. Disjoint information is the joint entropy of random variables\\u000a excluding the mutual information. This measure of statistical dependence and information redundancy satisfies more rigorous\\u000a metric conditions than mutual information, including self-similarity, minimality, symmetry

  3. SU-E-I-43: Pediatric CT Dose and Image Quality Optimization

    SciTech Connect

    Stevens, G; Singh, R [GE Healthcare, Waukesha, WI (United States)

    2014-06-01

    Purpose: To design an approach to optimize radiation dose and image quality for pediatric CT imaging, and to evaluate expected performance. Methods: A methodology was designed to quantify relative image quality as a function of CT image acquisition parameters. Image contrast and image noise were used to indicate expected conspicuity of objects, and a wide-cone system was used to minimize scan time for motion avoidance. A decision framework was designed to select acquisition parameters as a weighted combination of image quality and dose. Phantom tests were used to acquire images at multiple techniques to demonstrate expected contrast, noise and dose. Anthropomorphic phantoms with contrast inserts were imaged on a 160mm CT system with tube voltage capabilities as low as 70kVp. Previously acquired clinical images were us