Note: This page contains sample records for the topic artery image quality from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: August 15, 2014.
1

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

Microsoft Academic Search

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

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

2006-01-01

2

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

SciTech Connect

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

Hansis, Eberhard; Carroll, John D.; Schaefer, Dirk; Doessel, Olaf; Grass, Michael [Philips Technologie GmbH Forschungslaboratorien, Roentgenstrasse 24-26, 22335 Hamburg (Germany); Department of Medicine, Division of Cardiology, Health Sciences Center, University of Colorado, Denver, Colorado 80262 (United States); Philips Technologie GmbH Forschungslaboratorien, Roentgenstrasse 24-26, 22335 Hamburg (Germany); Institute of Biomedical Engineering, University of Karlsruhe, Kaiserstr. 12, 76131 Karlsruhe (Germany); Philips Technologie GmbH Forschungslaboratorien, Roentgenstrasse 24-26, 22335 Hamburg (Germany)

2010-04-15

3

Renal arteries (image)  

MedlinePLUS

... kidney. Contrast medium is then injected into the renal artery through the catheter, and images of the vessels of the kidney are taken. The test is a useful aid in evaluating kidney function and diagnosing any narrowing of the arteries, blood ...

4

Imaging Arterial Wall Disease  

Microsoft Academic Search

Ultrasonographic imaging of the carotid arteries allows assessment of both early and advanced atherosclerotic disease. This noninvasive technique has played a central role in many recent epidemiological studies and is being used increasingly for evaluating the efficacy of atherosclerosis prevention trials. New developments in ultrasound equipment, the use of echocontrast agents, novel applications of three- and four-dimensional sonography and in

Michael Hennerici; Stephen Meairs

2000-01-01

5

Coronary artery disease (image)  

MedlinePLUS

... through these arteries is critical for the heart. Coronary artery disease usually results from the build-up of fatty material and plaque, a condition called atherosclerosis. As the coronary arteries narrow, the flow of blood to the ...

6

Coronary artery fistula (image)  

MedlinePLUS

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

7

MR angiography of the supra-aortic arteries using a dedicated head and neck coil: image quality and assessment of stenoses.  

PubMed

Our purpose was to evaluate a dedicated head and neck coil for demonstration of supra-aortic arteries with optimised magnetic resonance angiography techniques. We performed 47 examinations with a 1.5-T system. We used coronal 3D fast imaging with steady precession (FISP), axial 3D tilted optimised nonsaturating excitation (TONE) and 2D fast low-angle shot (FLASH) for the carotid bifurcation, axial 3D TONE with or without magnetisation transfer (MT) for intracranial arteries, and axial 3D FISP or TONE for the aortic arch. Evaluation included visual assessment of image quality and grading of stenoses near the carotid bifurcation; digital subtraction angiography was used as the reference method. Axial 3D TONE gave superior image quality at the carotid bifurcation, MT-TONE intracranially, and 3D FISP for the aortic arch vessels. Nevertheless, sensitivity and specificity for detection of significant stenoses were similar with coronal 3D FISP (96.3%, 94.0%), axial 3D TONE (92.6%, 92.5%) and axial 2D FLASH (96.3%, 86.6%). Image quality at the aortic arch needs further improvement. PMID:9406200

Fellner, C; Strotzer, M; Fraunhofer, S; Held, P; Spies, V; Seitz, J; Fellner, F

1997-11-01

8

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.

9

Ultrasonic Imaging Of Deep Arteries  

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

10

Imaging of neonatal arterial thrombosis.  

PubMed Central

The case of a neonate who presented with symptoms of upper limb ischemia related to spontaneous multiple arterial and venous thromboses that were demonstrated by colour Doppler sonography and digital subtracted angiography is reported. The presentation of limb ischaemia at birth may be the warning sign of simultaneous cerebral infarction. Images Figure 1 Figure 2 Figure 3

Gudinchet, F; Dreyer, J L; Payot, M; Duvoisin, B; Laurini, R

1991-01-01

11

Image quality analyzer  

NASA Astrophysics Data System (ADS)

Image quality analyzer (IQA) which used as device for efficiency analysis of adaptive optics application is described. In analyzer marketed possibility estimations quality of images on three different criterions of quality images: contrast, sharpnesses and the spectral criterion. At present given analyzer is introduced on Big Solar Vacuum Telescope in stale work that allows at observations to conduct the choice of the most contrasting images of Sun. Is it hereinafter planned use the analyzer in composition of the ANGARA adaptive correction system.

Lukin, V. P.; Botugina, N. N.; Emaleev, O. N.; Antoshkin, L. V.; Konyaev, P. A.

2012-07-01

12

SSA Image Quality Modeling  

Microsoft Academic Search

This paper evaluates the ITIQUE image quality modeling framework for SSA applications. Based on Bovik and Sheik's VIF metric, ITIQUE evaluates the Shannon mutual information (MI) at multiple spatial scales between a pristine object and the image output from a detailed image formation chain simulation. Integrating the MI at each spatial scale and applying a calibration offset produces a prediction

C. Luna; D. Gerwe; B. Calef

2010-01-01

13

SSA Image Quality Modeling  

NASA Astrophysics Data System (ADS)

This paper evaluates the ITIQUE image quality modeling framework for SSA applications. Based on Bovik and Sheik’s VIF metric, ITIQUE evaluates the Shannon mutual information (MI) at multiple spatial scales between a pristine object and the image output from a detailed image formation chain simulation. Integrating the MI at each spatial scale and applying a calibration offset produces a prediction of NIIRS image quality indicating the level of interpretation tasks that could be supported. The model enables prediction of NIIRS quality obtainable as dependent on image collection conditions and image system design including both hardware and processing algorithms. The ITIQUE framework could facilitate concept evaluation and engineering design by quantitatively relating image formation performance directly in terms of end end-user mission needs. Previous work focused on overhead imagery of terrestrial scenes and linear processing only. This paper considers ground-based imaging of SSA targets and extends the previous study to include non-linear processing. A range of turbulence strengths and SNRs are included. ITIQUE predictions are shown to match well to results from a human visual assessment study in which a panel of human observers rated NIIRS quality of the same imagery.

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

2010-09-01

14

Coronary artery imaging system using gated tomosynthesis  

SciTech Connect

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

Macovski, A.

1987-05-05

15

Evaluation of image quality  

NASA Technical Reports Server (NTRS)

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.

Pavel, M.

1993-01-01

16

Quality Assurance Model of Operative Mortality in Coronary Artery Surgery.  

National Technical Information Service (NTIS)

Quality assurance in coronary artery bypass grafting (CABG) surgery requires a comparison of operative mortality against an accepted standard of care. Raw mortality statistics are unacceptable in this context, and risk factor analysis is essential. Howeve...

F. H. Edwards G. M. Graeber M. Barry R. Zajtchuk R. A. Albus

1989-01-01

17

Imaging in childhood arterial ischaemic stroke.  

PubMed

There remains a misconception that arterial ischaemic stroke (AIS) is a rare childhood disorder. Approximately 2-6/100,000 children are affected annually, and it is one of the top ten causes of childhood death. Following the ictus, up to 25% of children will have a recurrence, and two thirds of children will have a long-term disability with considerable socio-economic burden. The established vascular risk factors seen in adult stroke are rare in children. Instead, childhood AIS is associated with a variety of underlying aetiologies, including cerebral arteriopathies, sickle cell disease, cardio-embolic disease, infection, head and neck trauma, genetic/metabolic disease and prothrombotic abnormalities. Approximately 50% of children will have another recognised medical condition, and many children will have multiple risk factors. Given the complexity of the presentation and the potential ambiguity of the clinical findings, imaging is often the most revealing aspect of the diagnostic workup during both an acute and chronic presentation. This review considers the practical issues related to imaging children and looks at some of the controversies pertaining to aetiology and its implication for stroke management. It aims to give an overview of childhood arterial ischaemic stroke and to highlight the importance of both acute and delayed vascular imaging in the diagnosis, management and stratification of further stroke risk. PMID:20445969

Jones, Brynmor P; Ganesan, Vijya; Saunders, Dawn E; Chong, W Kling

2010-06-01

18

Magnetic resonance imaging of coronary arteries: technique and preliminary results  

Microsoft Academic Search

BACKGROUND--Coronary artery imaging is an important investigation for the management of coronary artery disease. The only reliable technique presently available, x ray contrast angiography, is invasive and is associated with a small morbidity and mortality. Alternative non-invasive imaging would be useful, but the small calibre and tortuosity of the coronary vessels, and cardiac and respiratory motion create formidable imaging problems.

D J Pennell; J Keegan; D N Firmin; P D Gatehouse; S R Underwood; D B Longmore

1993-01-01

19

A universal image quality index  

Microsoft Academic Search

We propose a new universal objective image quality index, which is easy to calculate and applicable to various image processing applications. Instead of using traditional error summation methods, the proposed index is designed by modeling any image distortion as a combination of three factors: loss of correlation, luminance distortion, and contrast distortion. Although the new index is mathematically defined and

Zhou Wang; Alan C. Bovik

2002-01-01

20

Retinal Image Quality During Accommodation  

PubMed Central

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.

Lopez-Gil, N.; Martin, J.; Liu, T.; Bradley, A.; Diaz-Munoz, D.; Thibos, L.

2013-01-01

21

Coronary artery remodeling in non-contrast CT images  

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

22

Optimizing image quality for SAR  

NASA Astrophysics Data System (ADS)

Image quality criteria for the design of a terrain mapping SAR are discussed. Basic resolution, degree of incoherent averaging and numbers of loits in the image are examined theoretically and with data collected over sea ice with the CCRS/ERIM SAR-580 system. The design of the INTERA STAR-1 radar along with suitable imagery, is used to demonstrate design principles.

Lowry, R. T.; Wessells, G. W.; Inkster, D. R.

1984-08-01

23

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

PubMed

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

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

2012-12-01

24

Coronary artery balloon angioplasty - series (image)  

MedlinePLUS

... of patients and may eliminate the need for coronary artery bypass surgery. The outcome is relief from chest pain symptoms ... coronary artery bypass graft surgery, also called a CABG) may be recommended.

25

Branching patterns of the male internal iliac artery: imaging findings  

Microsoft Academic Search

The aim of this study was to establish the imaging findings of the main branching patterns of the male internal iliac arteries,\\u000a using different imaging modalities (angio MR, angio CT and digital angiography). Twenty-one males (mean age 73.2 years) underwent\\u000a imaging evaluation with angio MR, angio CT and digital angiography to define the internal iliac artery anatomy before selective\\u000a embolization of

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

2011-01-01

26

"Mirror-image" bilateral giants: intracavernous carotid artery aneurysms.  

PubMed

Summary: The literature on the incidence of "mirror image" bilateral giant intracavernous aneurysms, their symptoms and their association with other entities is reviewed, with a brief comment on their evolution and treatment. A case of "mirror image" bilateral giant intracavernous aneurysms in a 76-year-old man who presented a sudden diplopia with pupillary sparing is reported. A CT scan showed parasellar images and dolichomega circle of Willis arteries that enhanced with endovenous contrast. MRI and angiography disclose bilateral aneurysms in detail, associated with an anomalous origin of the left common carotid artery and bilateral renal artery stenosis. PMID:20569579

Díaz, M B; Mercado, F C; Lemme Plaghos, L A

2006-09-15

27

"Mirror-Image" Bilateral Giants: Intracavernous Carotid Artery Aneurysms  

PubMed Central

Summary The literature on the incidence of "mirror image" bilateral giant intracavernous aneurysms, their symptoms and their association with other entities is reviewed, with a brief comment on their evolution and treatment. A case of "mirror image" bilateral giant intracavernous aneurysms in a 76-year-old man who presented a sudden diplopia with pupillary sparing is reported. A CT scan showed parasellar images and dolichomega circle of Willis arteries that enhanced with endovenous contrast. MRI and angiography disclose bilateral aneurysms in detail, associated with an anomalous origin of the left common carotid artery and bilateral renal artery stenosis.

Diaz, M.B.; Mercado, F.C.; Lemme Plaghos, L.A.

2006-01-01

28

Vascular intramural strain imaging using arterial pressure equalization  

Microsoft Academic Search

Peripheral vascular strain imaging has limited strain dynamic range because arterial wall deformations only exhibit small strains under physiologic pressures. A noninvasive freehand ultrasound (US) scanning procedure was performed to apply external force, comparable to the force generated in measuring a subject's blood pressure, to achieve higher strains by equalizing the internal arterial baseline pressure. When the applied pressure matched

Kang Kim; W. F. Weitzel; J. M. Rubin; Hua Xie; Xunchang Chen; M. O'Donnell

2004-01-01

29

Estimation of Coronary Arterial Wall Strain in Clinical Ivus Images  

Microsoft Academic Search

In this study, we propose a practical method to estimate cross-sectional wall strain distribution of coronary arteries from clinically acquired intravascular ultrasound (IVUS) images in continuous pullback mode. First, cardiac phase information is retrieved retrospectively from an IVUS image sequence using an image-based gating method, and image sub-sequences at systole and diastole are extracted. Images at branch sites are used

Yun Liang; Hui Zhu; Thomas Gehrig; Morton H. Friedman

2007-01-01

30

Landsat image data quality studies  

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

31

ACS CCD Image Quality Verification  

NASA Astrophysics Data System (ADS)

This program will obtain a series of images to evaluate the point source image quality over the fields of view of the ACS HRC and WFC channels in normal imaging {non-coronagraphic} mode, after the corrector mechanisms have been used to optimize the image focus and symmetry. A moderate density open cluster, NGC-188, will be the target, since it is available year-round and has suitable density and magnitude distribution. Images will be obtained in the F502N and F625W filters, with 0.5 px dithers in each axis of the WFC to improve PSF sampling. Larger { 10 arcsec} POS-TARG offsets will be used to improve the sampling over the HRC field, while maintaining mean star separation {>5 arcsec} adequate for PSF evaluation to a reasonable radius. This corresponds to activity ACS17;

Fruchter, Andrew

2008-07-01

32

ACS CCD Image Quality Verification  

NASA Astrophysics Data System (ADS)

This program will obtain a series of images to evaluate the point source image quality over the fields of view of the ACS HRC and WFC channels in normal imaging {non-coronagraphic} mode, after the corrector mechanisms have been used to optimize the image focus and symmetry. A moderate density open cluster, NGC-188, will be the target, since it is available year-round and has suitable density and magnitude distribution. Images will be obtained in the F502N and F625W filters, with 0.5 px dithers in each axis of the WFC to improve PSF sampling. Larger { 10 arcsec} POS-TARG offsets will be used to improve the sampling over the HRC field, while maintaining mean star separation {>5 arcsec} adequate for PSF evaluation to a reasonable radius.

Hartig, George

2001-07-01

33

Latent and apparent image quality metrics  

Microsoft Academic Search

Measures of image quality are presented here that have been developed to assess both the immediate quality of an image and the potential at intermediate points in an imaging chain for enhanced image quality. The original intent of the metric(s) was to provide an optimand for interpolator design, and the metrics have subsequently been used for a number of differential

Kristo S. Miettinen

2002-01-01

34

[Arterial switch operation for transposition of the great arteries with situs inversus and mirror image dextrocardia].  

PubMed

We report a successful arterial switch operation for complete transposition of great arteries with atrial and visceral situs inversus totalis and mirror image dextrocardia in a 12-day-old infant girl. The aorta was located left side-by-side to the pulmonary trunk with a single coronary artery (mirror image of 1RLCx). After French maneuver, the posterior circumference of the neo-aorta was reconstructed. Then the coronary button was transplanted into the neo-aorta with a trap door technique carefully avoiding any twist and over-stretch. The neo-pulmonary trunk was reconstructed with an autologous pericardial patch and sutured to the longitudinal incision made into the left central pulmonary artery. The baby was discharged from hospital and has been doing well without any morbidity relating myocardial ischemia. PMID:22940657

Uchida, Hiroaki; Nemoto, Shintaro; Ozawa, Hideki; Sasaki, Tomoyasu; Motohashi, Yoshikazu; Katsumata, Takahiro; Inoue, Nao; Kishi, Kanta; Okumura, Kenichi; Mori, Yasuhiko

2012-09-01

35

Imaging of carotid artery disease: from luminology to function?  

Microsoft Academic Search

There have been tremendous advances in our ability to image atheromatous disease, particularly in the carotid artery, which is accessible and large enough to image. The repertoire of methodology available is growing, giving anatomical information on luminal narrowing which is approaching the level at which conventional carotid angiography will become very uncommon as CT and contrast-enhanced MR angiographic techniques become

J. H. Gillard

2003-01-01

36

Tissue Classification of Arterial Wall Based on Elasticity Image  

NASA Astrophysics Data System (ADS)

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, fibrous tissues (mixture of smooth-muscle and collagen fiber), blood clots and calcified tissues. From these previous studies, it was found that arterial tissues can be classified into soft tissues (lipids and blood clots) and hard tissues (fibrous tissue and calcified tissue) on the basis of their elasticity. However, it was difficult to differentiate lipids from blood clots and also fibrous tissue from calcified tissue. In this study, we investigated how to improve the tissue classification of the arterial wall using statistical properties of the elasticity distribution of each tissue.

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

2006-05-01

37

Dynamic diffuse optical tomography imaging of peripheral arterial disease  

PubMed Central

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.

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

2012-01-01

38

Imaging in childhood arterial ischaemic stroke  

Microsoft Academic Search

There remains a misconception that arterial ischaemic stroke (AIS) is a rare childhood disorder. Approximately 2–6\\/100,000\\u000a children are affected annually, and it is one of the top ten causes of childhood death. Following the ictus, up to 25% of\\u000a children will have a recurrence, and two thirds of children will have a long-term disability with considerable socio-economic\\u000a burden. The established

Brynmor P. Jones; Vijya Ganesan; Dawn E. Saunders; W. “Kling” Chong

2010-01-01

39

Image quality metrics based on scale  

NASA Astrophysics Data System (ADS)

This paper presents a method to evaluate image quality using the continuous wavelet transform. The method utilizes a bank of filters tuned to different scales and orientations to extract the image details. The filters are designed according to the criterion suggested by Antoine and Murenzi. The wavelet transform of a given image and the reconstructed images at various quality levels are represented in the form of energy density plots. These density plots highlight image features such as edges, object boundaries and texture. Thus, they represent the details contained in the image. A quality metric is proposed based on the absolute difference between the energy densities corresponding to the original and reconstructed images. The proposed metric is used to measure the relative quality of the image. In addition, the metric is also used to study the performance of a specific ATR algorithm as a function of image quality.

Namuduri, Kameswara R.; Murenzi, Romain; Kaplan, Lance M.; Johnson, Davida

1998-03-01

40

Referenceless image quality evaluation for whole slide imaging  

PubMed Central

Objective: The image quality in whole slide imaging (WSI) is one of the most important issues for the practical use of WSI scanners. In this paper, we proposed an image quality evaluation method for scanned slide images in which no reference image is required. Methods: While most of the conventional methods for no-reference evaluation only deal with one image degradation at a time, the proposed method is capable of assessing both blur and noise by using an evaluation index which is calculated using the sharpness and noise information of the images in a given training data set by linear regression analysis. The linear regression coefficients can be determined in two ways depending on the purpose of the evaluation. For objective quality evaluation, the coefficients are determined using a reference image with mean square error as the objective value in the analysis. On the other hand, for subjective quality evaluation, the subjective scores given by human observers are used as the objective values in the analysis. The predictive linear regression models for the objective and subjective image quality evaluations, which were constructed using training images, were then used on test data wherein the calculated objective values are construed as the evaluation indices. Results: The results of our experiments confirmed the effectiveness of the proposed image quality evaluation method in both objective and subjective image quality measurements. Finally, we demonstrated the application of the proposed evaluation method to the WSI image quality assessment and automatic rescanning in the WSI scanner.

Hashimoto, Noriaki; Bautista, Pinky A.; Yamaguchi, Masahiro; Ohyama, Nagaaki; Yagi, Yukako

2012-01-01

41

Process perspective on image quality evaluation  

NASA Astrophysics Data System (ADS)

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

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

2008-01-01

42

Diagnosis and management of pulmonary arterial hypertension using MR imaging.  

PubMed

Pulmonary arterial hypertension (PAH) is a syndrome that results from restricted blood flow through the pulmonary arterial circulation, which leads to a pathological increase in pulmonary vascular resistance (PVR) and ultimately to right heart failure. The prognosis of patients with PAH has improved with the recent development of new medications. The need for new noninvasive diagnostic tools is increasing. Magnetic resonance (MR) imaging is the gold standard for assessing the right ventricle (RV). Its high degree of reproducibility makes it ideal for monitoring changes in RV parameters in response to therapy. MR imaging can also provide both anatomical and functional information about pulmonary hemodynamics. This article reviews the current status of MR imaging of the right side of the heart and pulmonary circulation in patients with PAH and other associated pulmonary diseases. PMID:23474963

Iwasawa, Tae

2013-03-25

43

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

PubMed

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

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

2011-08-01

44

Phase congruency assesses hyperspectral image quality  

NASA Astrophysics Data System (ADS)

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

Shao, Xiaopeng; Zhong, Cheng

2012-10-01

45

Latent and apparent image quality metrics  

NASA Astrophysics Data System (ADS)

Measures of image quality are presented here that have been developed to assess both the immediate quality of an image and the potential at intermediate points in an imaging chain for enhanced image quality. The original intent of the metric(s) was to provide an optimand for interpolator design, and the metrics have subsequently been used for a number of differential image quality analyses and imaging system component designs. The metrics presented are of the same general form as the National Imagery Interpretability Rating Scale (NIIRS), representing quality as the base-2 logarithm of linear resolution, so that one unit of differential quality represents a doubling or halving of the resolution of imagery. Analysis of a simple imaging chain is presented in terms of the metrics, with conclusions regarding interpolator design, consistency of the latent and apparent image quality metrics, and the relationship between interpolator and convolution kernel design in a system where both are present. Among the principal results are an optimized division of labor between interpolators and Modulation Transfer Function Correction (MTFC) filters, consistency of the analytical latent and apparent image quality metrics with each other and with visually optimized aim curves, and an introduction to sharpening interpolator design methodology.

Miettinen, Kristo S.

2002-07-01

46

Assessment of coronary artery stenosis by magnetic resonance imaging.  

PubMed Central

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

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

1996-01-01

47

Three-dimensional color Doppler imaging of the carotid artery  

NASA Astrophysics Data System (ADS)

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.

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

1991-05-01

48

Image quality of figured multilayered optics  

SciTech Connect

The reflectivity and resolution of a multilayer structure is strongly affected by the roughness at the interfaces between two successive layers and by the amount that the constituent materials will diffuse into one another at the interfaces. Performance is also affected by the variations in individual layer thicknesses and by inhomogeneities in the materials. These deviations from the ideal multilayer will also affect the quality of the image from a figured multilayer optical element. The theory used to model the effects of non-ideal multilayers on the image quality of figured optics will be discussed. The relationship between image quality and multilayer structure quality will be illustrated with several examples.

Peterson, B.G.; Knight, L.V.; Pew, H.K.

1985-01-01

49

Retinal image quality assessment using generic features  

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

50

Quality assurance for diagnostic imaging equipment  

SciTech Connect

This report addresses factors that influence production of an image. It contains the necessary information to enable the imaging physician to report the diagnostic findings to the referring physician. Some of these factors are human, other are inherent to technique and equipment. The subject of the report is quality assurance, i.e., all of the management practices instituted by the imaging physician, to assure highest quality medical care, but an essential element of quality assurance is quality control. The first three sections are concerned with quality assurance in general and the remainder with quality control in specific circumstances. This report provides a systematic approach to procedures which can ensure that the physician and the imaging facility consistently achieve their optimal performance. This in turn, ensures that there is optimal use of radiation and that radiation exposures to patient and staff are maintained at a level consistent with the principles of optimization of radiation protection espoused by the NCRP.

Not Available

1988-01-01

51

Imaging of a Renal Artery Aneurysm Detected Incidentally on Ultrasonography  

PubMed Central

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.

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

2014-01-01

52

Image structure clustering for image quality verification of color retina images in diabetic retinopathy screening  

Microsoft Academic Search

Reliable verification of image quality of retinal screening images is a prerequisite for the development of automatic screening systems for diabetic retinopathy.A system is presented that can automatically determine whether the quality of a retinal screening image is sufficient for automatic analysis. The system is based on the assumption that an image of sufficient quality should contain particular image structures

Meindert Niemeijer; Michael D. Abràmoff; Bram van Ginneken

2006-01-01

53

Image quality assessment based on distortion identification  

NASA Astrophysics Data System (ADS)

A New Global Full-Reference Image Quality System based on classification and fusion scheme is proposed. It consists of many steps. The first step is devoted to the identification of the type of degradation contained in a given image based a Linear Discriminant Analysis (LDA) classifier using some common Image Quality Metric (IQM) as feature inputs. An IQM per degradation (IQM-D) is then used to estimate the quality of the image. For a given degradation type, the appropriate IQM-D is derived by combining the top three best IQMs using an Artificial Neural Network model. The performance of the proposed scheme is evaluated first in terms of good degradation identification. Then, for each distortion type the image quality estimation is evaluated in terms of good correlation with the subjective judgments using the TID 2008 image database.

Chetouani, Aladine; Beghdadi, Azeddine

2011-01-01

54

Functional magnetic resonance imaging in renal artery stenosis  

Microsoft Academic Search

Renal artery stenosis (RAS) is the leading cause of secondary hypertension. Magnetic resonance (MR) imaging and in particular\\u000a MR angiography have evolved into important diagnostic tools for the detection and grading of RAS due to the lack of ionizing\\u000a radiation and nephrotoxic contrast agent. This review describes state-of-the-art MR angiographic techniques and introduces\\u000a the reader to current concepts of RAS

S. O. Schoenberg; J. R. Rieger; H. J. Michaely; H. Rupprecht; W. Samtleben; M. F. Reiser

2006-01-01

55

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

SciTech Connect

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

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

1985-05-01

56

Visual Quality Evaluation for Images and Videos  

Microsoft Academic Search

\\u000a Information is exploding with technology progress. Compared with text and audio, image and video can represent information\\u000a more vividly, which makes visual quality one of the most important aspects in determining user experience. A good visual quality\\u000a evaluation method can assist in monitoring the quality of multimedia services and boosting user experience.

Songnan Li; Lawrence Chun-Man Mak; King Ngan

57

Image compression quality rating using anchored scales  

NASA Astrophysics Data System (ADS)

Traditional image quality rating schemes use descriptive scales applicable to wide ranges of quality. These scales, based on equal interval verbal descriptors, cannot be used for restricted ranges of quality now encountered in image compression studies. Although numerical category scales have been successfully used in some studies for quantifying small variations in quality arising from lossy image compression, problems arise in more general image coding applications. In this work, we propose a double anchored numerical category scale based on a 3-context visual assessment scheme for image coding applications. The goal is to devise a common subjective scale applicable to a set of images produced from multiple scenes compressed by multiple coding algorithms. Therefore, the contexts are in the use of distinct coders and distinct images. The first two contexts, using a specific image scene, are the visibility of specific coder induced artifacts and the visibility of artifacts arising from different coders. In the third context, the artifact visibility is in terms of the content of different image scenes. Separate scales are obtained for images differing in scene content and for each coding algorithm, using numerical category scaling with explicit high and low anchors. These scales are linked using pairwise matching techniques to obtain a robust image quality sale.

Avadhanam, Niranjan; Algazi, V. Ralph

1998-04-01

58

General Image-Quality Equation: GIQE  

Microsoft Academic Search

A regression-based model was developed relating aerial image quality, expressed in terms of the National Imagery Interpretability Rating Scale (NIIRS), to fundamental image attributes. The General Image-Quality Equation (GIQE) treats three main attributes: scale, expressed as the ground-sampled distance; sharpness, measured from the system modulation transfer function; and the signal-to-noise ratio. The GIQE can be applied to any visible sensor

Jon C. Leachtenauer; William Malila; John Irvine; Linda Colburn; Nanette Salvaggio

1997-01-01

59

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

PubMed

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

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

2014-07-01

60

A new image quality assessment database for tiled images  

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

61

Use of intravascular imaging in managing coronary artery disease  

PubMed Central

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.

Jegere, Sanda; Narbute, Inga; Erglis, Andrejs

2014-01-01

62

Computerized assessment and tracking of cardiac angiographic image quality  

NASA Astrophysics Data System (ADS)

With the rising prominence of filmless and quantitative imaging technologies in modern cardiac catheterization laboratories, new approaches to assessing angiographic image quality (AIQ) are required. This paper describes a system of radiographic phantom modules and associated digital image analysis software for assessing and tracking the inherent low contrast AIQ of a particular image chain as well as its suitability for quantitative coronary arteriography (QCA) analysis. The system uses two phantom modules in conjunction with a patient simulation apparatus. Computer software operates on digital radiographic images of the phantoms and extracts a number of parameters characterizing the imaging performance of the particular image chain. An arterial phantom module is used to evaluate angiographic imaging performance relating to QCA and an orthogonal array of small bronze ball bearings is used to derive AIQ parameters that complement standard manual measurements. In addition to passively monitoring AIQ, this new approach has the benefit of enabling active compensation for variability in AIQ and its effect on QCA results from one image chain to the next.

Lefree, Michelle T.; Krus, Daniel L.; Sitomer, Joseph

1998-07-01

63

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

NASA Astrophysics Data System (ADS)

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.

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

2003-05-01

64

[Magnetic resonance imaging in the diagnosis of retrotracheal pulmonary artery].  

PubMed

The authors report the case of a 3-month-old infant with a history of interventricular septal defect with pulmonary arterial hypertension. This child had pulmonary symptomatology (dyspnea, recurrent bronchitis, acute attacks of asphyxia) which it was possible to link to a retrotracheal left pulmonary artery by magnetic resonance imaging (MRI). Classical investigations (upper GI barium series and chest X-ray) were suggestive of a bronchogenic cyst type abnormal pulmonary structure. Angiography confirmed the MRI diagnosis. In this case the infant also had tracheal lesions (lower tracheal hypoplasia) which required further evaluation by fibroscopy and bronchography. Thus MRI shows itself to be a useful investigation in the study of basic vascular abnormalities. PMID:2024907

Livolsi, A; Donato, L; Kastler, B; Willard, D; Geisert, J

1991-01-01

65

Pleiades-Hr Image Quality Commissioning  

NASA Astrophysics Data System (ADS)

PLEIADES is the highest resolution civilian earth observing system ever developed in Europe. This imagery program is conducted by the French National Space Agency, CNES. It operates since 2012 a first satellite PLEIADES-HR launched on 2011 December 17th, a second one should be launched by the end of the year. Each satellite is designed to provide optical 70 cm resolution coloured images to civilian and defence users. The Image Quality requirements were defined from users studies from the different spatial imaging applications, taking into account the trade-off between on-board technological complexity and ground processing capacity. The assessment of the image quality and the calibration operation have been performed by CNES Image Quality team during the 6 month commissioning phase that followed the satellite launch. These activities cover many topics gathered in two families : radiometric and geometric image quality. The new capabilities offered by PLEIADES-HR agility allowed to imagine new methods of image calibration and performance assessment. Starting from an overview of the satellite characteristics, this paper presents all the calibration operations that were conducted during the commissioning phase and also gives the main results for every image quality performance.

Lebègue, L.; Greslou, D.; de Lussy, F.; Fourest, S.; Blanchet, G.,; Latry, C.; Lachérade, L.; Delvit, J. M.; Kubik, P.; Déchoz, C.; Amberg, V.; Porez-Nadal, F.

2012-07-01

66

Indium-111 labeled leukocyte imaging following hepatic artery embolization  

SciTech Connect

The use of In-111 labeled leukocytes for abscess localization is becoming well established. The first report of In-111 imaging following hepatic embolization is presented. A 45-year-old man with adenocarcinoma of the colon and metastatic liver disease was treated for intractable pain using particulate embolization of the hepatic artery. In-111 leukocyte imaging was performed to rule out abscess formation. The distribution of the labeled leukocytes demonstrated hepatic uptake commensurate with Tc-99m sulfur colloid (SC) images. Areas of embolization did not accumulate tracer. Pathologic examination at autopsy correlated with the distribution of the labeled leukocytes. Thus, therapeutic embolization did not alter the normal distribution of this tracer in functional hepatic tissue.

Witte, R.J.; Petersen, R.J.; Augustine, S.C.; Elson, J.D.

1986-05-01

67

General Image-Quality Equation: GIQE.  

PubMed

A regression-based model was developed relating aerial image quality, expressed in terms of the National Imagery Interpretability Rating Scale (NIIRS), to fundamental image attributes. The General Image-Quality Equation (GIQE) treats three main attributes: scale, expressed as the ground-sampled distance; sharpness, measured from the system modulation transfer function; and the signal-to-noise ratio. The GIQE can be applied to any visible sensor and predicts NIIRS ratings with a standard error of 0.3 NIIRS. The image attributes treated by the GIQE are influenced by system design and operation parameters. The GIQE allows system designers and operators to perform trade-offs for the optimization of image quality. PMID:18264373

Leachtenauer, J C; Malila, W; Irvine, J; Colburn, L; Salvaggio, N

1997-11-10

68

General Image-Quality Equation: GIQE  

NASA Astrophysics Data System (ADS)

A regression-based model was developed relating aerial image quality, expressed in terms of the National Imagery Interpretability Rating Scale (NIIRS), to fundamental image attributes. The General Image-Quality Equation (GIQE) treats three main attributes: scale, expressed as the ground-sampled distance; sharpness, measured from the system modulation transfer function; and the signal-to-noise ratio. The GIQE can be applied to any visible sensor and predicts NIIRS ratings with a standard error of 0.3 NIIRS. The image attributes treated by the GIQE are influenced by system design and operation parameters. The GIQE allows system designers and operators to perform trade-offs for the optimization of image quality.

Leachtenauer, Jon C.; Malila, William; Irvine, John; Colburn, Linda; Salvaggio, Nanette

1997-11-01

69

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

SciTech Connect

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.

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

70

Myocardial perfusion imaging with technetium-99m sestamibi SPECT in the evaluation of coronary artery disease  

SciTech Connect

Technetium-99m (Tc-99m) sestamibi is a new myocardial perfusion imaging agent that offers significant advantages over thallium-201 (Tl-201) for myocardial perfusion imaging. The results of the current clinical trials using acquisition and processing parameters similar to those for Tl-201 and a separate (2-day) injection protocol suggest that Tc-99m sestamibi and Tl-201 single photon emission computed tomography (SPECT) provide similar information with respect to detection of myocardial perfusion defects, assessment of the pattern of defect reversibility, overall detection of coronary artery disease (CAD) and detection of disease in individual coronary arteries. Tc-99m sestamibi SPECT appears to be superior to Tc-99m sestamibi planar imaging because the former provides a higher defect contrast and is more accurate for detection of disease in individual coronary arteries. Research is currently under way addressing optimization of acquisition and processing of Tc-99m sestamibi studies and development of quantitative algorithms for detection and localization of CAD and sizing of transmural and nontransmural myocardial perfusion defects. It is expected that with the implementation of the final results of these new developments, further significant improvement in image quality will be attained, which in turn will further increase the confidence in image interpretation. Development of algorithms for analysis of end-diastolic myocardial images may allow better evaluation of small and nontransmural myocardial defects. Furthermore, gated studies may provide valuable information with respect to regional myocardial wall motion and wall thickening. With the implementation of algorithms for attenuation and scatter correction, the overall specificity of Tc-99m sestamibi SPECT should improve significantly. 32 references.

Maddahi, J.; Kiat, H.; Van Train, K.F.; Prigent, F.; Friedman, J.; Garcia, E.V.; Alazraki, N.; DePuey, E.G.; Nichols, K.; Berman, D.S. (Cedars-Sinai Medical Center, Los Angeles, CA (USA))

1990-10-16

71

Propagation, structural similarity, and image quality  

NASA Astrophysics Data System (ADS)

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.

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

2012-05-01

72

No training blind image quality assessment  

NASA Astrophysics Data System (ADS)

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.

Chu, Ying; Mou, Xuanqin; Ji, Zhen

2014-03-01

73

Image quality measures and their performance  

Microsoft Academic Search

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. A graphical measure

Ahmet M. Eskicioglu; Paul S. Fisher

1995-01-01

74

Image Quality Measurement Using Integer Wavelet Transformations  

Microsoft Academic Search

We present a novel and straightforward method of graphical and scalar image quality measurement utilising integer wavelet transformations. The measure can represent separately the components of image distortion such as noise and blur through relative energy in the wavelet transform subbands. The measure can perform a similar function to the Hosaka plot whilst not requiring segmentation and threshold parameters. Through

K. J. Hermiston; David M. Booth

1999-01-01

75

Quality of life of children after repair of transposition of the great arteries  

Microsoft Academic Search

Background—We sought to assess quality of life of children with transposition of the great arteries (TGA) enrolled during transition in management strategy from atrial to arterial switch operation. Methods and Results—Neonates enrolled by the Congenital Heart Surgeons Society in a prospective study of TGA between 1985 and 1989 were eligible. A Child Health Questionnaire was sent for completion by the

Erin L. Culbert; David A. Ashburn; Geraldine Cullen-Dean; Jay A. Joseph; William G. Williams; Eugene H. Blackstone; Brian W. McCrindle

2003-01-01

76

Quality of Life Improvement after Robotically Assisted Coronary Artery Bypass Grafting  

Microsoft Academic Search

Objectives: Coronary artery bypass grafting (CABG) is associated with long rehabilitation periods and slow quality of life (QOL) improvement. Totally endoscopic coronary artery bypass grafting (TECAB) can be performed using robotic technology and remote access perfusion. The aim of this study was to evaluate whether TECAB leads to accelerated QOL improvement as compared to standard CABG. Methods: We included 120

Nikolaos Bonaros; Thomas Schachner; Dominik Wiedemann; Armin Oehlinger; Elisabeth Ruetzler; Gudrun Feuchtner; Christian Kolbitsch; Corinna Velik-Salchner; Guy Friedrich; Othmar Pachinger; Guenther Laufer; Johannes Bonatti

2009-01-01

77

Online artery diameter measurement in ultrasound images using artificial neural networks  

Microsoft Academic Search

An automated online technique is described for measurement of artery diameter in flow-mediated dilation (FMD) ultrasound (US) images, using artificial neural networks to identify and track artery walls. This allows FMD results to be calculated without the inherent delay of current retrospective methods. Two networks were trained to identify artery anterior and posterior walls using over 3200 examples from carotid

V. R Newey; D. K Nassiri

2002-01-01

78

Perceptual image quality and telescope performance ranking  

NASA Astrophysics Data System (ADS)

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.

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

2010-08-01

79

Analysis of the general image quality equation  

NASA Astrophysics Data System (ADS)

The general image quality equation (GIQE) [Leachtenauer et al., Appl. Opt. 36, 8322-8328 (1997)] is an empirical formula for predicting the quality of imagery from a given incoherent optical system in terms of the National Imagery Interpretability Rating Scale (NIIRS). In some scenarios, the two versions of the GIQE (versions 3.0 and 4.0) yield significantly different NIIRS predictions. We compare visual image quality assessments for simulated imagery with GIQE predictions and analyze the physical basis for the GIQE terms in an effort to determine the proper coefficients for use with Wiener-filtered reconstructions of Nyquist and oversampled imagery in the absence of aberrations. Results indicate that GIQE 3.0 image quality predictions are more accurate than those from GIQE 4.0 in this scenario.

Thurman, Samuel T.; Fienup, James R.

2008-05-01

80

Color image processing for date quality evaluation  

NASA Astrophysics Data System (ADS)

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.

Lee, Dah Jye; Archibald, James K.

2010-01-01

81

The Development and Potential of Acoustic Radiation Force Impulse (ARFI) Imaging for Carotid Artery Plaque Characterization  

PubMed Central

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

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

2012-01-01

82

Arterial Spin Labeled MRI Perfusion Imaging: Clinical Applications  

PubMed Central

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).

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

2009-01-01

83

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

PubMed Central

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.

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

2014-01-01

84

Noninvasive In Vivo Human Coronary Artery Lumen and Wall Imaging Using Black-Blood Magnetic Resonance Imaging  

Microsoft Academic Search

Background—High-resolution MRI has the potential to noninvasively image the human coronary artery wall and define the degree and nature of coronary artery disease. Coronary artery imaging by MR has been limited by artifacts related to blood flow and motion and by low spatial resolution. Methods and Results—We used a noninvasive black-blood (BB) MRI (BB-MR) method, free of motion and blood-flow

Zahi A. Fayad; Valentin Fuster; John T. Fallon; Timothy Jayasundera; Stephen G. Worthley; Gerard Helft; J. Gilberto Aguinaldo; Juan J. Badimon; Samin K. Sharma

2010-01-01

85

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

PubMed

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

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

2013-12-01

86

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

PubMed Central

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.

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

87

Synchrotron radiation dichromographic imaging of the extra- and intracranial arterial circulations and choroid plexus  

NASA Astrophysics Data System (ADS)

This communication proposes the use of synchrotron radiation based k-edge dichromographic imaging for the simultaneous study of the extracranial and intracranial arterial circulations following a single peripheral intravenous injection of a contrast agent. This approach can provide images of the vertebral arteries, the common, external and internal carotid arteries, as well as the intracranial arteries, during a single scanning procedure, lasting only a few seconds, requiring an X-ray exposure on the order of about 30 mGy/image. The method has specific advantages for the evaluation of the perfusion of the choroid plexus.

Rubenstein, E.

2002-05-01

88

New imaging techniques for diagnosing coronary artery disease  

PubMed Central

New tomographic cardiovascular imaging tests, such as intravascular ultrasonography (IVUS), coronary computed tomography (CT) angiography and magnetic resonance imaging (MRI), can be used to assess atherosclerotic plaques for the characterization and early staging of coronary artery disease (CAD). Although IVUS images have very high resolution capable of revealing very early preclinical CAD, it is an invasive technique used clinically only in conjunction with a coronary intervention. Multiple-slice coronary CT angiography, which is noninvasive, shows promise as a diagnostic method for CAD. New 64-slice cardiac CT technology has high accuracy for the detection of lesions obstructing more than 50% of the lumen, with sensitivity, specificity, and positive and negative predictive values all better than 90% in patients without known CAD. Cardiac MRI is also improving accuracy in coronary plaque detection and offers a better opportunity for plaque characterization. With further advances in tomographic imaging of coronary atheromas, the goal will be to detect plaques earlier in the development of CAD and to characterize the plaques most likely to generate a clinical event.

Escolar, Esteban; Weigold, Guy; Fuisz, Anthon; Weissman, Neil J.

2006-01-01

89

New imaging techniques for diagnosing coronary artery disease.  

PubMed

New tomographic cardiovascular imaging tests, such as intravascular ultrasonography (IVUS), coronary computed tomography (CT) angiography and magnetic resonance imaging (MRI), can be used to assess atherosclerotic plaques for the characterization and early staging of coronary artery disease (CAD). Although IVUS images have very high resolution capable of revealing very early preclinical CAD, it is an invasive technique used clinically only in conjunction with a coronary intervention. Multiple-slice coronary CT angiography, which is noninvasive, shows promise as a diagnostic method for CAD. New 64-slice cardiac CT technology has high accuracy for the detection of lesions obstructing more than 50% of the lumen, with sensitivity, specificity, and positive and negative predictive values all better than 90% in patients without known CAD. Cardiac MRI is also improving accuracy in coronary plaque detection and offers a better opportunity for plaque characterization. With further advances in tomographic imaging of coronary atheromas, the goal will be to detect plaques earlier in the development of CAD and to characterize the plaques most likely to generate a clinical event. PMID:16477061

Escolar, Esteban; Weigold, Guy; Fuisz, Anthon; Weissman, Neil J

2006-02-14

90

Imaging appearances and management of isolated spontaneous dissection of the superior mesenteric artery  

Microsoft Academic Search

ObjectiveThe objective of our study was to report the clinical and imaging features of isolated dissection of the superior mesenteric artery (SMA) and describe our imaging classification of this disease entity.

Ichiro Sakamoto; Yoji Ogawa; Eijun Sueyoshi; Kenichiro Fukui; Tomonori Murakami; Masataka Uetani

2007-01-01

91

Lessions learned in WISE image quality  

NASA Astrophysics Data System (ADS)

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

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

2010-08-01

92

Analysis of the general image quality equation  

Microsoft Academic Search

The general image quality equation (GIQE) [Leachtenauer et al., Appl. Opt. 36, 8322-8328 (1997)] is an empirical formula for predicting the quality of imagery from a given incoherent optical system in terms of the National Imagery Interpretability Rating Scale (NIIRS). In some scenarios, the two versions of the GIQE (versions 3.0 and 4.0) yield significantly different NIIRS predictions. We compare

Samuel T. Thurman; James R. Fienup

2008-01-01

93

Analysis of the general image quality equation  

Microsoft Academic Search

The general image quality equation (GIQE) (Leachtenauer et al., Appl. Opt. 36, 8322-8328 (1997)) is an empirical formula for predicting the quality of imagery from a given incoherent optical system in terms of the National Imagery Interpretability Rating Scale (NIIRS). In some scenarios, the two versions of the GIQE (versions 3.0 and 4.0) yield significantly different NIIRS predictions. We compare

Samuel T. Thurman; James R. Fienup

2008-01-01

94

Image-Based Computational Fluid Dynamics Modeling in Realistic Arterial Geometries  

Microsoft Academic Search

Local hemodynamics are an important factor in atherosclerosis, from the development of early lesions, to the assessment of stroke risk, to determining the ultimate fate of a mature plaque. Until recently, our understanding of arterial fluid dynamics and their relationship to atherosclerosis was limited by the use of idealized or averaged artery models. Recent advances in medical imaging, computerized image

David A. Steinman

2002-01-01

95

Image quality measurement besides distortion type classifying  

Microsoft Academic Search

To identify the distortion type and quantify the quality of images, a new method is presented based on a comparison among\\u000a the structural properties as well as consideration of the luminance characteristics of the two compared images. To fulfill\\u000a this aim, the mathematical concept of the singular value decomposition (SVD) theorem has been applied. The difference vector\\u000a of the reflection

Ahmad Mahmoudi-Aznaveh; Azadeh Mansouri; Farah Torkamani-Azar; Mohammad Eslami

2009-01-01

96

Imaging the basilar artery by contrast-enhanced color-coded ultrasound.  

PubMed

Conventional transcranial color-coded real-time sonography of the vertebrobasilar system is limited by imaging problems of the distal segment of the basilar artery. Lung-stable contrast-enhancing agents may overcome this problem by enhancing the quality of Doppler signals by as much as 20%. Fourty-two patients underwent sonographic evaluation of the vertebrobasilar system before and after receiving intravenously administered galactose-based contrast-enhancing agent Levovist by transforaminal and transtemporal routes. Imaging quality was classified into five categories depending on the length of visible color-flow by transforaminal approach: 1--no signal, 2--1-9.9 mm, 3--10-19.9 mm, 4--20-29.9 mm, 5--> or = 30 mm. For transtemporal insonation, imaging quality was classified either as no color flow or sufficient color flow of the basilar tip. By unenhanced investigation, average signal length of color flow was 16 +/- 8 mm for transforaminal investigation; application of Levovist improved this value to 26.6 +/- 6 mm. For unenhanced transforminal approach, 4.8% were assigned to category 1, 11.9% to category 2, 54.8% to category 3, 23.8% to category 4 and 4.8% to category 5. After signal enhancement with Levovist, category 1 covered 0%, category 2 2.4%, category 3 7.14%, category 4 59.5% and category 5 30.9% (p < 0.001). Unenhanced transtemporal approach allowed identification of the basilar tip in 78.6% with an average length of 6.3 +/- 2 mm; contrast enhancement improved this values to 92.9% and 8.3 +/- 3.3 mm respectively (p < 0.05). The application of transpulmonary contrast-enhancing agents improves the reliability of transcranial color-coded duplex sonography of the basilar artery. PMID:11147396

Iglseder, B; Huemer, M; Staffen, W; Ladurner, G

2000-10-01

97

Visualization of Coronary Wall Atherosclerosis in Asymptomatic Subjects and Patients with Coronary Artery Disease Using Magnetic Resonance Imaging  

Microsoft Academic Search

BackgroundMagnetic resonance imaging (MRI) is sensitive to early atherosclerotic changes such as positive remodeling in patients with coronary artery disease (CAD). We assessed prevalence, quality, and extent of coronary atherosclerosis in a group of healthy subjects compared to patients with confirmed CAD.MethodologyTwenty-two patients with confirmed CAD (15M, 7F, mean age 60.4±10.4 years) and 26 healthy subjects without history of CAD

Suzanne C. Gerretsen; M. Eline Kooi; Alfons G. Kessels; Simon Schalla; Marcus Katoh; Rob J. van der Geest; Warren J. Manning; Johannes Waltenberger; Jos M. A. van Engelshoven; Rene M. Botnar; Tim Leiner

2010-01-01

98

Blood vessel classification into arteries and veins in retinal images  

NASA Astrophysics Data System (ADS)

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.

Kondermann, Claudia; Kondermann, Daniel; Yan, Michelle

2007-03-01

99

Online artery diameter measurement in ultrasound images using artificial neural networks.  

PubMed

An automated online technique is described for measurement of artery diameter in flow-mediated dilation (FMD) ultrasound (US) images, using artificial neural networks to identify and track artery walls. This allows FMD results to be calculated without the inherent delay of current retrospective methods. Two networks were trained to identify artery anterior and posterior walls using over 3200 examples from carotid artery images. Both networks correctly classified approximately 97% of the randomly selected test samples. The technique was verified using a physical model with absolute measurement error of -1.16% +/- 1.04% (mean +/- SD) over the diameter range 2 to 8 mm. Advantages of the technique include: online analysis; wall tracking optimisation before the study proper; measurement of diameter changes over the cardiac cycle; low FMD measurement variance; minimal image degradation; and no unwieldy image store. Measurement of artery diameter changes over the cardiac cycle was explored using simulated image sequences generated with a virtual US scanner. PMID:11937284

Newey, V R; Nassiri, D K

2002-02-01

100

Quantitative metrics to evaluate image quality for computed radiographic images  

NASA Astrophysics Data System (ADS)

Traditional methods of evaluating a computed radiography (CR) imaging system's performance (e.g. the noise power spectrum (NPS), the modulation transfer function (MTF), the detective quantum efficiency (DQE) and contrast-detail analysis) were adapted in order to evaluate the feasibility of identifying a quantitative metric to evaluate image quality for digital radiographic images. The addition of simulated patient scattering media when acquiring the images to calculate these parameters altered their fundamental meaning. To avoid confusion with other research they were renamed the clinical noise power spectrum (NPSC), the clinical modulation transfer function (MTFC), the clinical detective quantum efficiency (DQEC) and the clinical contrast detail score (CDSC). These metrics were then compared to the subjective evaluation of radiographic images of an anthropomorphic phantom representing a one-year old pediatric patient. Computer algorithms were developed to implement the traditional mathematical procedures for calculating the system performance parameters. In order to easily compare these three metrics, the integral up to the system Nyquist frequency was used as the final image quality metric. These metrics are identified as the INPSC, the IMTFC and the IDQEC respectively. A computer algorithm was also developed, based on the results of the observer study, to determine the threshold contrast to noise ratio (CNRT) for objects of different sizes. This algorithm was then used to determine the CDSC by scoring images without the use of observers. The four image quality metrics identified in this study were evaluated to determine if they could distinguish between small changes in image acquisition parameters e.g., current-time product and peak-tube potential. All of the metrics were able to distinguish these small changes in at least one of the image acquisition parameters, but the ability to digitally manipulate the raw image data made the identification of a broad indicator of image quality not possible. The contrast-detail observer study revealed important information about how the noise content in an image affects the low-contrast detectability of different sized objects. Since the CNRT for each object size in the contrast-detail phantoms was almost independent of the exposure level, the minimum CNRT that would be necessary for an object of that size to be 'visible' in a clinical image was identified. Finally, in order to determine more refined CNRT values (due to possible observer biases from the physical construction of the contrast-detail phantoms available for this study) the design of new contrast detail phantoms is proposed.

Pitcher, Christopher D.

101

Tissue Doppler imaging in coronary artery diseases and heart failure.  

PubMed

Recent studies have explored the prognostic role of TDI-derived parameters in major cardiac diseases, such as coronary artery disease (CAD) and heart failure (HF). In these conditions, myocardial mitral annular systolic (S') and early diastolic (E') velocities have been shown to predict mortality or cardiovascular events. In heart failure non invasive assessment of LV diastolic pressure by transmitral to mitral annular early diastolic velocity ratio (E/E') is a strong prognosticator, especially when E/E' is > or =15. Moreover, other parameters derived by TDI, as cardiac time intervals and Myocardial Performance Index, might play a role in the prognostic stratification in CAD and HF. Recently, a three-dimensional (3-D) TDI imaging modality, triplane TDI, has become available, and this allows calculation of 3-Dvolumes and LV ejection fraction. We present a brief update of TDI. PMID:22845815

Correale, Michele; Totaro, Antonio; Ieva, Riccardo; Ferraretti, Armando; Musaico, Francesco; Di Biase, Matteo

2012-02-01

102

Tissue Doppler Imaging in Coronary Artery Diseases and Heart Failure  

PubMed Central

Recent studies have explored the prognostic role of TDI-derived parameters in major cardiac diseases, such as coronary artery disease (CAD) and heart failure (HF). In these conditions, myocardial mitral annular systolic (S’) and early diastolic (E’) velocities have been shown to predict mortality or cardiovascular events. In heart failure non invasive assessment of LV diastolic pressure by transmitral to mitral annular early diastolic velocity ratio (E/E’) is a strong prognosticator, especially when E/E’ is > or =15. Moreover, other parameters derived by TDI, as cardiac time intervals and Myocardial Performance Index, might play a role in the prognostic stratification in CAD and HF. Recently, a three-dimensional (3-D) TDI imaging modality, triplane TDI, has become available, and this allows calculation of 3-Dvolumes and LV ejection fraction. We present a brief update of TDI.

Correale, Michele; Totaro, Antonio; Ieva, Riccardo; Ferraretti, Armando; Musaico, Francesco; Biase, Matteo Di

2012-01-01

103

Multimodality image fusion for diagnosing coronary artery disease  

PubMed Central

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.

Piccinelli, Marina; Garcia, Ernest

2013-01-01

104

Color face-tuned salient detection for image quality assessment  

Microsoft Academic Search

PSNRHVS and PSNRHVSM are two new emerging image quality assessment methods but they fail when assessing the quality of some distorted images called as “extreme” images. In this paper an algorithm is proposed to enhance their performance on extreme images while keeping their good performance on “normal” images unchanged. First, extreme images derived from PSNRHVS are labeled with an iterative

Tong Yubing; Hubert Konik; Alain Tremeau

2010-01-01

105

Hypercomplex Quality Assessment of Multi\\/Hyperspectral Images  

Microsoft Academic Search

This letter presents a novel image quality index which extends the Universal Image Quality Index for monochrome images to multispectral and hyperspectral images through hypercomplex numbers. The proposed index is based on the computation of the hypercomplex correlation coefficient between the reference and tested images, which jointly measures spectral and spatial distortions. Experimental results, both from true and simulated images,

Andrea Garzelli; Filippo Nencini

2009-01-01

106

Image quality measures and their performance  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

107

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

NASA Astrophysics Data System (ADS)

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.

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

108

Enhancement and segmentation for NMR images of blood flow in arteries  

NASA Astrophysics Data System (ADS)

STRACT The widespread prevalence of atherosclerotic vascular disease has given rise to the need for a simple noninvasive imaging examination of the cardiovascular performance of patients. The potential of using Magnetic Resonance (MR) Imaging to quantify flow in vivo has for reaching possibilities for the future of preventive medicine. In this paper we address the problem of using MR velocity imaging to analyse the flow boundaries in human arteries which are of great importance to the early diagnosis ef occlusive diseases. A flow related enhancement process is introduced in this paper. It is designed to suppress the residuals and the noisy background of the MR velocity images caused by misregistration tissue movement and uneven magnetic field and provide great improvement in signal to noise ratio. From the enhanced image the main flow areas can be delineated by a thresholding process which defines the kernel of the flow. The boundaries of the kernel region are then dynamically guided by a defined flow boundary localization process to their final positions. The results of the application of this coarse to fine process show its robustness and effectiveness for the determination of the blood blow boundaries form very low quality MR velocity images.

Yang, Guang-Zhong; Burger, Peter

1990-09-01

109

Assessment of artery dilation by using image registration based on spatial features  

NASA Astrophysics Data System (ADS)

The use of affine image registration based on normalized mutual information (NMI) has recently been proposed by Frangi et al. as an automatic method for assessing brachial artery flow mediated dilation (FMD) for the characterization of endothelial function. Even though this method solves many problems of previous approaches, there are still some situations that can lead to misregistration between frames, such as the presence of adjacent vessels due to probe movement, muscle fibres or poor image quality. Despite its widespread use as a registration metric and its promising results, MI is not the panacea and can occasionally fail. Previous work has attempted to include spatial information into the image similarity metric. Among these methods the direct estimation of ?-MI through Minimum Euclidean Graphs allows to include spatial information and it seems suitable to tackle the registration problem in vascular images, where well oriented structures corresponding to vessel walls and muscle fibres are present. The purpose of this work is twofold. Firstly, we aim to evaluate the effect of including spatial information in the performance of the method suggested by Frangi et al. by using ?-MI of spatial features as similarity metric. Secondly, the application of image registration to long image sequences in which both rigid motion and deformation are present will be used as a benchmark to prove the value of ?-MI as a similarity metric, and will also allow us to make a comparative study with respect to NMI.

Oubel, Estanislao; Neemuchwala, Huzefa; Hero, Alfred; Boisrobert, Loic; Laclaustra, Martin; Frangi, Alejandro F.

2005-04-01

110

Geometric assessment of image quality using digital image registration techniques  

NASA Technical Reports Server (NTRS)

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

Tisdale, G. E.

1976-01-01

111

Image Quality in Analog and Digital Microtechniques.  

ERIC Educational Resources Information Center

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)

White, William

1991-01-01

112

PHYSICAL IMAGE QUALITY EVALUATION OF MEDICAL RADIOGRAPHS  

Microsoft Academic Search

The noise equivalent quanta (NEQ) has been recommended as a measure of physical quality of medical images. Digitised data of medical radiographs in a previous work have been analysed in terms of resolution via the modulation transfer function (MTF) and noise via the noise power spectrum (NPS), but not in terms of NEQ. As the NEQ is currently regarded as

Muhamad Saridan; Wan Hassan; Yusof Munajat; Shamsul Sahibuddin

113

FFDM image quality assessment using computerized image texture analysis  

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

114

High frequency intravascular photoacoustic (IVPA) imaging for differentiating arterial wall layered structures  

NASA Astrophysics Data System (ADS)

Arterial wall is composed of three layers: intima, media and adventitia. Intima-media thickness (IMT) is an important prognostic indicator of atherosclerotic diseases. Although intravascular ultrasound (IVUS) imaging is a commonly used method for delineation of the layered structures, it is inferior to the optical absorption contrast offered by intravascular photoacoustic (IVPA) imaging. We introduce an integrated miniature probe that combines the capabilities of IVUS and IVPA imaging for the evaluation of arterial wall layered structures. Healthy rabbit aorta was imaged ex vivo. IVPA results showed superior contrast over IVUS in identifying the layered structures of arterial wall.

Li, Xiang; Wei, Wei; Zhou, Qifa; Shung, K. Kirk; Chen, Zhongping

2012-02-01

115

Image Quality Indicator for Infrared Inspections  

NASA Technical Reports Server (NTRS)

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.

Burke, Eric

2011-01-01

116

Naturalness and interestingness of test images for visual quality evaluation  

NASA Astrophysics Data System (ADS)

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

Halonen, Raisa; Westman, Stina; Oittinen, Pirkko

2011-01-01

117

Prediction of Viking lander camera image quality  

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

118

Neurological Outcome and Quality of Life after Stroke due to Vertebral Artery Dissection  

Microsoft Academic Search

Background: Vertebral artery dissection is a well-recognized cause of posterior circulation stroke for which there is relatively little information on long-term outcomes. Quality of life (QOL) is an important patient-centred outcome measure. Methods: Stroke due to vertebral artery dissection was conservatively defined by neuroimaging documentation. Thirty sequential cases were identified based on a retrospective database and chart review with prospective

Diana Czechowsky; Michael D. Hill

2002-01-01

119

Saliency image of feature building for image quality assessment  

NASA Astrophysics Data System (ADS)

The purpose and method of image quality assessment are quite different for automatic target recognition (ATR) and traditional application. Local invariant feature detectors, mainly including corner detectors, blob detectors and region detectors etc., are widely applied for ATR. A saliency model of feature was proposed to evaluate feasibility of ATR in this paper. The first step consisted of computing the first-order derivatives on horizontal orientation and vertical orientation, and computing DoG maps in different scales respectively. Next, saliency images of feature were built based auto-correlation matrix in different scale. Then, saliency images of feature of different scales amalgamated. Experiment were performed on a large test set, including infrared images and optical images, and the result showed that the salient regions computed by this model were consistent with real feature regions computed by mostly local invariant feature extraction algorithms.

Ju, Xinuo; Sun, Jiyin; Wang, Peng

2011-11-01

120

Physiological modulations in arterial spin labeling perfusion magnetic resonance imaging.  

PubMed

The purpose of this study is to evaluate cardiac and respiratory modulations in the signals of arterial spin labeling (ASL) perfusion magnetic resonance imaging (MRI) using RETROICOR, an image domain based retrospective correction method. Systematic comparisons were conducted for tagging schemes, pulsed (PASL) versus frequency-modulated continuous (CASL) methods, and the use of background suppression (BGS). Results showed that cardiac pulsation accounted for more signal fluctuation in PASL than in CASL (two-tailed paired Student's t-test, p < 10(-3)), whereas no significant difference was found in the effect of respiratory motion ( p=0.55) on the two tagging schemes studied. For PASL, significantly more improvement was achieved by the inclusion of cardiac pulsation than respiratory motion in RETROICOR ( p < 0.01). On the contrary, the inclusion of respiratory motion offers more improvement for CASL ( p < 0.02). BGS effectively improved the temporal signal-to-noise ratio (tSNR) as previous studies reported, but no significant difference was measured in the spectral power of physiological modulations relative to the entire spectrum of PASL signals before and after the superimposition of BGS ( p=0.63 for cardiac component, p=0.67 for respiratory component). Thus, we conclude that BGS reduces noise without spectral selectivity, and the improvements of tSNR from RETROICOR and BGS are additive. CASL with a labeling duration at a multiple of an R-R interval can be used to minimize signal fluctuation originating from cardiac pulsation. PMID:19150788

Wu, Wen-Chau; Edlow, Brian L; Elliot, Mark A; Wang, Jiongjiong; Detre, John A

2009-05-01

121

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

NASA Astrophysics Data System (ADS)

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.

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

2008-04-01

122

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

SciTech Connect

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

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

1980-11-01

123

Noninvasive estimation of the arterial input function in positron emission tomography imaging of cerebral blood flow  

PubMed Central

Positron emission tomography (PET) with 15O-labeled water can provide reliable measurement of cerebral blood flow (CBF). Quantification of CBF requires knowledge of the arterial input function (AIF), which is usually provided by arterial blood sampling. However, arterial sampling is invasive. Moreover, the blood generally is sampled at the wrist, which does not perfectly represent the AIF of the brain, because of the effects of delay and dispersion. We developed and validated a new noninvasive method to obtain the AIF directly by PET imaging of the internal carotid artery in a region of interest (ROI) defined by coregistered high-resolution magnetic resonance angiography. An ROI centered at the petrous portion of the internal carotid artery was defined, and the AIF was estimated simultaneously with whole brain blood flow. The image-derived AIF (IDAIF) method was validated against conventional arterial sampling. The IDAIF generated highly reproducible CBF estimations, generally in good agreement with the conventional technique.

Su, Yi; Arbelaez, Ana M; Benzinger, Tammie L S; Snyder, Abraham Z; Vlassenko, Andrei G; Mintun, Mark A; Raichle, Marcus E

2013-01-01

124

Value of Magnetic Resonance Imaging for the Noninvasive Detection of Stenosis in Coronary Artery Bypass Grafts and Recipient Coronary Arteries  

Microsoft Academic Search

Background—Magnetic resonance imaging (MRI) is a potential noninvasive diagnostic tool to detect coronary artery bypass graft stenosis, but its value in clinical practice remains to be established. We investigated the value of MRI in detecting stenotic grafts, including recipient vessels. Methods and Results—We screened for inclusion 173 consecutive patients who were scheduled for coronary angiography because of recurrent chest pain

Susan E. Langerak; Hubert W. Vliegen; J. Wouter Jukema; Patrik Kunz; Aeilko H. Zwinderman; Hildo J. Lamb; Ernst E. van der Wall; Albert de Roos

2010-01-01

125

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

PubMed

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

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

2014-02-01

126

Long-term outcome and quality of life after arterial switch operation: a prospective study with a historical comparison.  

PubMed

AIM.: The study aims to describe the long-term cardiological and psychological results of our first surgical cohort of arterial switch operation (ASO) patients and compare the results with our earlier series of Mustard patients. METHODS.: Twenty-four survivors of ASO operated in our center (1985-1990) were evaluated by electrocardiography, echocardiography, magnetic resonance imaging, exercise testing, 24-hour Holter-monitoring, and health-related quality of life questionnaire. The results were compared with 58 adult Mustard patients who were evaluated in 2001 using the same study protocol. RESULTS.: Arterial switch operation was performed at a median age of 13 days and Mustard operation at 2 years. Median follow-up was 22 years (range 20-25) and 25 years (22-29), respectively. After ASO, survival was better (P =.04). The event-free survival after 22 years was 77% after ASO vs. 44% after Mustard (P =.03). Good systemic ventricular function was present in 93% after ASO vs. 6% after Mustard (P <.01). Exercise capacity in ASO was 85% of predicted, compared with 72% in Mustard patients (P =.01). Aortic regurgitation was found in 21% of ASO patients vs. 16% in Mustard patients. Arterial switch patients vs. Mustard patients reported significantly better quality of life and less somatic complaints. CONCLUSION.: The progression made in surgical treatment for transposition of the great arteries from Mustard to ASO has had a positive impact on survival, cardiac function, exercise capacity, and also self-reported quality of life and somatic complaints. Longer follow-up is warranted to monitor aortic regurgitation. PMID:23350828

Ruys, Titia P E; van der Bosch, Annemien E; Cuypers, Judith A A E; Witsenburg, Maarten; Helbing, Willem A; Bogers, Ad J J C; van Domburg, Ron; McGhie, Jacky S; Geleijnse, Marcel L; Henrichs, Jens; Utens, Elisabeth; Van der Zwaan, Heleen B; Takkenberg, Johanna J M; Roos-Hesselink, Jolien W

2013-01-01

127

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

NASA Astrophysics Data System (ADS)

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

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

1999-09-01

128

Infrared image quality assessment based on fractal dimension method  

NASA Astrophysics Data System (ADS)

The operation and observation experience of users is affected by the quality of infrared images which are collected by infrared imager. And image quality is a significant indicator for the performance of image processing algorithm and the optimization of system parameters as well. An image quality reduced reference assessment model is put forward to evaluate the degree of infrared image quality reduction. The detail characteristic of infrared image texture is extracted by the fractal dimension analysis method proposed in this paper as the representation of image quality. The method computes the fractal dimension of every pixel one by one with a multi-scale window over the entire image to get the information of corresponding image block. A quality information image is mapped from the fractal dimension of all pixels to describe the infrared image quality. The parameters of the quality information image combined with the peak SNR of original infrared image are adopted as the metric of infrared image quality. The method can be embedded into image processing system to optimize image processing algorithms and parameters settings, and provide reference for fault diagnosis.

Zhang, Zhijie; Zhang, Jufeng; Yue, Song; Wang, Chensheng

2012-12-01

129

An Image Quality Assessment Method based on HVS  

Microsoft Academic Search

The detection performance of X-ray security inspection systems can be reflected from the image quality generated by the system. The image quality assessment method proposed in the paper combines human visual system (HVS) with objective method to evaluation the image quality of X-ray system. The assessment process and method simulate the human vision characteristics to separate and analyze regions of

Wu Wei

2007-01-01

130

Eyetracking based approach to objective image quality assessment  

Microsoft Academic Search

This paper presents an approach to predict perceived quality of compressed images while incorporating real visual attention coordinates. Information about the visual attention is not usually taken into account in models for image quality assessment. The idea of implementing gaze information into the image quality assessment system lies in that the artefacts are more disturbing to human observer in the

Karel Fliegel

2008-01-01

131

Image Quality Measurement Using Sparse Extreme Learning Machine Classifier  

Microsoft Academic Search

In this paper, we present a machine learning approach to measure the visual quality of JPEG-coded images. The features for predicting the perceived image quality are extracted by considering key human visual sensitivity factors such as edge amplitude, edge length, background activity and background luminance. Image quality estimation involves computation of functional relationship between HVS features and subjective test scores.

S. Suresh; R. Venkatesh Babu; Narasimhan Sundararajan

2006-01-01

132

Multi-Modality Image Fusion to Guide Peripheral Artery Chronic Total Arterial Occlusion Recanalization in a Swine Carotid Artery Occlusion Model: Unblinding the Interventionalist!  

PubMed Central

Objectives To demonstrate the feasibility of magnetic resonance imaging (MRI) to x-ray fluoroscopy (XRF) image fusion to guide peripheral artery chronic total occlusion (CTO) recanalization. Background Endovascular peripheral artery CTO revascularization is minimally invasive, but challenging, because the occlusion is poorly visualized under XRF. Devices may steer out of the artery which can lead to severe perforation. Merging pre-acquired MRI of the CTO to the live XRF display may permit upfront use of aggressive devices and improve procedural outcomes. Methods Swine carotid artery CTO’s were created using a balloon injury model. Up to 8 weeks later, MRI of the carotid arteries was acquired and segmented to create 3D surface models, which were then registered onto live XRF. CTO recanalization was performed using incrementally aggressive CTO devices (Group A) or an upfront aggressive directed laser approach (Group B). Procedural success was defined as luminal or sub-intimal device position without severe perforation. Results In this swine model, MRI to XRF fusion guidance resulted in a procedural success of 57% in Group A and 100% in Group B, which compared favorably to 33% using XRF alone. Fluoroscopy time was significantly less for Group B (8.5 min ± 2.6 min) compared to Group A (48.7 min ± 23.9 min), p value<0.01. Contrast dose used was similar between Groups A and B. Conclusions MRI to XRF fusion guided peripheral artery CTO recanalization is feasible. Multi-modality image fusion may permit upfront use of aggressive CTO devices with improved procedural outcomes compared to XRF guided procedures.

Klein, Andrew J.; Tomkowiak, Michael T.; Vigen, Karl K.; Hacker, Timothy A.; Speidel, Michael A.; VanLysel, Michael S.; Shah, Nehal; Raval, Amish N.

2012-01-01

133

Multi-Slice Cerebral Blood Flow Imaging With Continuous Arterial Spin Labeling MRI.  

National Technical Information Service (NTIS)

This invention is a method for multi-slice CBF imaging using continuous arterial spin labeling (CASL) with an amplitude modulated control which is both highly effective at controlling for off resonance effects, and efficient at doubly inverting inflow spi...

D. C. Alsop

2005-01-01

134

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

National Technical Information Service (NTIS)

The synchrotron based coronary angiography project at the National Synchrotron Light Source obtains images of coronary arteries using the digital subtraction technique after a distal venous injection of an iodine contrast agent. It allows two areal mass d...

D. Chapman C. Schulze

1994-01-01

135

Image and Video Quality Assessment Using Neural Network and SVM  

Microsoft Academic Search

An image and video quality assessment method was developed using neural network and support vector machines (SVM) with the peak signal to noise ratio (PSNR) and the structure similarity indexes used to describe image quality. The neural network was used to obtain the mapping functions between the objective quality assessment indexes and subjective quality assessment. The SVM was used to

Wenrui Ding; Yubing Tong; Qishan Zhang; Dongkai Yang

2008-01-01

136

Transorbital Color Doppler Flow Imaging of the Carotid Siphon and Major Arteries at the Base of the Brain  

Microsoft Academic Search

PURPOSE: To describe and evaluate an application of sonography, transorbital color Doppler flow imaging of the carotid siphon and major intracranial arteries, and to compare it with transtemporal color Doppler flow imaging. METHODS: The carotid siphon and major arteries at the base of the brain of 50 healthy volunteers were screened using the transorbital color Doppler flow sonography. These arteries

Han-Hwa Hu; Cheau-Lin Luo; Wen-Yung Sheng; Michael Mu-Huo Teng; Wen-Jang Wong; Yun-On Luk

137

Susceptibility-weighted imaging in differentiating bilateral medial thalamic venous and arterial infarcts.  

PubMed

Bilateral medial thalamic infarcts may be due to thrombosis of internal cerebral veins or occlusion of artery of Percheron. Conventional MR imaging is often not helpful in differentiating the two. We discuss two cases in whom susceptibility-weighted imaging, including phase images contributed in demonstrating the thrombosed or patent internal cerebral veins. PMID:20739805

Chatterjee, Somenath; Thomas, Bejoy; Kesavadas, Chandrasekhar; Kapilamoorthy, Tirur Raman

2010-01-01

138

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

PubMed

Our earlier study developed a computerized method, based on fuzzy connected object delineation principles and algorithms, for artery and vein separation in contrast enhanced Magnetic Resonance Angiography (CE-MRA) images. This paper reports its current development-a software package-for routine clinical use. The software package, termed 3DVIEWNIX-AVS, consists of the following major operational parts: (1) converting data from DICOM3 to 3DVIEWNIX format, (2) previewing slices and creating VOI and MIP Shell, (3) segmenting vessel, (4) separating artery and vein, (5) shell rendering vascular structures and creating animations. This package has been applied to EPIX Medical Inc's CE-MRA data (AngioMark MS-325). One hundred and thirty-five original CE-MRA data sets (of 52 patients) from 6 hospitals have been processed. In all case studies, unified parameter settings produce correct artery-vein separation. The current package is running on a Pentium PC under Linux and the total computation time per study is about 3 min. The strengths of this software package are (1) minimal user interaction, (2) minimal anatomic knowledge requirements on human vascular system, (3) clinically required speed, (4) free entry to any operational stages, (5) reproducible, reliable, high quality of results, and (6) cost effective computer implementation. To date, it seems to be the only software package (using an image processing approach) available for artery and vein separation of the human vascular system for routine use in a clinical setting. PMID:12821028

Lei, Tianhu; Udupa, Jayaram K; Odhner, Dewey; Nyúl, László G; Saha, Punam K

2003-01-01

139

Colour Doppler Imaging of Ophthalmic Artery and Central Retinal Artery in Glaucoma Patients with and without Diabetes Mellitus  

PubMed Central

Purpose: To assess the ocular blood flow in Diabetic and non-Diabetic Primary Open Angle Glaucoma (POAG) patients. Design: Prospective comparitive study. Material and Methods: A total 100 eyes of 50 POAG patients was included in the study and divided into two groups, Group 1 (25 POAG patients without Diabetes mellitus) and Group 2 (25 POAG patients with Diabetes mellitus). Colour Doppler Imaging (CDI) of Ophthalmic artery and Central retinal artery were studied and peak systolic velocity (V max), End diastolic velocity (V min) and Resistivity Index (RI) were assessed. Results: Ocular blood flow in Group 2 showed a reduction in V max, V min and increased RI compared to Group I with a statistically significant reduction in the central retinal artery flow (V max (p=0.01), V min (p=0.07) and RI (p=0.03). Conclusion: CDI showed a significant reduction in the ocular blood flow of POAG patients with Diabetes mellitus.

Kumar, M. Ashok; Selvasundari, S.; Prakash, M. L.

2014-01-01

140

Carotid and vertebral artery dissections: clinical aspects, imaging features and endovascular treatment  

Microsoft Academic Search

Extracranial arterial dissections are a recognised cause of stroke, particularly in young adults. Clinical diagnosis may be\\u000a difficult, and the classical triad of symptoms is uncommon. Imaging plays a pivotal role in the diagnosis of extracranial\\u000a arterial dissections, and this review provides a detailed discussion of the relative merits and limitations of currently available\\u000a imaging modalities. Conventional arteriography has been

Christine M. Flis; H. Rolf Jäger; Paul S. Sidhu

2007-01-01

141

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

SciTech Connect

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.

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

142

Improving Secondary Ion Mass Spectrometry Image Quality with Image Fusion  

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

143

Pulmonary artery sarcoma diagnosed using intravascular ultrasound images  

PubMed Central

Primary and secondary malignant intravascular tumours of the pulmonary artery occur infrequently and the diagnosis is usually delayed as symptoms and findings from conventional examinations are non-specific. The case is presented of a patient with a pulmonary artery sarcoma, probably arising from ribs resected some years previously, in which intravascular ultrasound (IVUS) provided important diagnostic findings.??

Okano, Y.; Satoh, T.; Tatewaki, T.; Kunieda, T.; Fukuyama, S.; Miyazaki, N.; Beppu, Y.

1999-01-01

144

Reconstruction algorithm for improved ultrasound image quality.  

PubMed

A new algorithm is proposed for reconstructing raw RF data into ultrasound images. Previous delay-and-sum beamforming reconstruction algorithms are essentially onedimensional, 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 fieldof- 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

Madore, Bruno; Meral, F

2012-02-01

145

Model-based quantification of image quality  

NASA Technical Reports Server (NTRS)

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

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

1989-01-01

146

Enhancement and quality control of GOES images  

NASA Astrophysics Data System (ADS)

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

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

1996-10-01

147

CFHT Image Quality and the Observing Environment  

NASA Astrophysics Data System (ADS)

We analyze stellar images on 36,520 exposures made in the u, g, r, i, and z bands with MegaCam at the focus of the 3.6 m Canada-France-Hawai'i Telescope between 2005 August and 2008 August. The effect on image quality (IQ) of temperature differences (?Ts) in the telescope environment and of wind speed and direction are first examined and discussed. The contributions of the optics to image spread are then estimated and the frequency distribution of the observatory-free site seeing is obtained. The main findings are: (1) In the convective mode, the thermally-induced image full width at half-maximum intensity (FWHM) grows with the temperature gradient and path length L at the rate of ˜0.2?·(?T/L6/5·L3/5. (2) For a given |?T|, thermal convection is ˜3 times more detrimental to image quality than thermal inversions. (3) The orientation of the dome slit with respect to the wind direction has important effects on IQ. (4) The median observatory induced seeing is 0.43? FWHM. (5) The FWHM caused by the optics and slight optomechanical imperfections ranges from 0.46? in u to 0.28? in i. (6) The median DIMM-scale zenith atmospheric seeing at a wavelength of 500 nm and an elevation of 17 m above ground at the CFHT site is 0.55?. (7) The characteristics value of the outer scale of turbulence is 30 m. The paper addresses various issues bearing on the management of facility seeing.

Salmon, Derrick; Cuillandre, Jean-Charles; Barrick, Gregory; Thomas, Jim; Ho, Kevin; Matsushige, Grant; Benedict, Tom; Racine, René

2009-08-01

148

Quality of Life in Stroke Survivors after Local Intra-Arterial Thrombolysis  

Microsoft Academic Search

Background: We aimed to assess quality of life (QOL) and its predictors in stroke survivors after local intra-arterial thrombolysis (IAT) as well as to measure QOL according to the site of pretreatment vessel occlusion. Methods: From January 2000 to April 2004, 175 consecutive patients underwent IAT for acute ischemic stroke. Clinical and radiological data were collected prospectively. We contacted 135

Urs Fischer; Diana Anca; Marcel Arnold; Krassen Nedeltchev; Liliane Kappeler; Pietro Ballinari; Gerhard Schroth; Heinrich P. Mattle

2008-01-01

149

Effect of Arterial Incisions on the Amount of Bleeding and Flesh Quality of Rainbow Trout.  

National Technical Information Service (NTIS)

Arteries of rainbow trout, Salmo gairdneri, were severed at the isthmus, nape, and caudal peduncle, and blood loss was measured. The quality of flesh, after being frozen up to 8 months, was superior for bled fish as evaluated by appearance, odor, and lipi...

W. I. Tretsven B. G. Patten

1981-01-01

150

Autofluorescence maps of atherosclerotic human arteries - A new technique in medical imaging  

SciTech Connect

A new medical imaging technique for arterial walls based on laser-induced autofluorescence spectroscopy is reported. The internal surface of isolated arteries with or without atherosclerosis is irradiated with an argon ion laser (458 nm) and the peak intensity of the excited autofluorescence spectrum is related to the composition of the arterial wall. The higher autofluorescence intensity in the range between approximately 480 and 630 nm for grossly calcified tissue compared to normal or noncalcified atherosclerotic tissue is used to produce maps of the arterial wall. These images delineate the calcified areas of the sample with good spatial resolution. If this technique can be adapted to the endoscopic visualization of arteries in vivo (angioscopy), it could become an important tool for the diagnosis of atherosclerosis and for the monitoring of atheroma ablation during laser angioplasty.

Sartori, M.; Sauerbrey, R.; Kubodera, S.; Tittel, F.K.; Roberts, R.; Henry, P.D.

1987-10-01

151

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

PubMed

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

Sifakis, Emmanouil G; Golemati, Spyretta

2014-09-01

152

The mobile image quality survey game  

NASA Astrophysics Data System (ADS)

In this paper we discuss human assessment of the quality of photographic still images, that are degraded in various manners relative to an original, for example due to compression or noise. In particular, we examine and present results from a technique where observers view images on a mobile device, perform pairwise comparisons, identify defects in the images, and interact with the display to indicate the location of the defects. The technique measures the response time and accuracy of the responses. By posing the survey in a form similar to a game, providing performance feedback to the observer, the technique attempts to increase the engagement of the observers, and to avoid exhausting observers, a factor that is often a problem for subjective surveys. The results are compared with the known physical magnitudes of the defects and with results from similar web-based surveys. The strengths and weaknesses of the technique are discussed. Possible extensions of the technique to video quality assessment are also discussed.

Rasmussen, D. René

2012-01-01

153

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

NASA Astrophysics Data System (ADS)

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

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

2011-08-01

154

On pictures and stuff: image quality and material appearance  

NASA Astrophysics Data System (ADS)

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.

Ferwerda, James A.

2014-02-01

155

Evaluation of measures of technical image quality for intracranial magnetic resonance angiography.  

PubMed

We evaluate three measures of technical image quality for intracranial magnetic resonance angiography (MRA): (1) a two-alternative forced choice (2AFC) evaluation of vessel visibility, (2) vessel-to-background signal-difference-to-noise ratio (SDNR), and (3) observer ranking of the fidelity of vessel morphology compared to that in a gold standard image. The gold standard used for both the 2AFC and ranking measures is intraarterial catheter angiography. These measures are applied to healthy arterial segments. The 2AFC and SDNR measures directly evaluate the visibility of artery segments for which the existence is known from the gold standard images. We argue that (1) 2AFC evaluates the carrier signals on which any vascular disease process is modulated and provides an upper bound on the detectibility of vascular lesions, (2) SDNR is a predictor of 2AFC, and (3) ranking may be used to predict the relative performance of techniques in the detection of vascular lesions. PMID:10587470

Chapman, B E; Goodrich, C K; Alexander, A L; Blatter, D D; Parker, D L

1999-12-01

156

Finger vein image quality evaluation using support vector machines  

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

157

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

NASA Astrophysics Data System (ADS)

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.

Tozian, Cynthia

158

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

PubMed

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

Mirsharif, Qazaleh; Tajeripour, Farshad; Pourreza, Hamidreza

2013-01-01

159

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

PubMed Central

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

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

2013-01-01

160

Assessment of coronary artery stenosis by magnetic resonance imaging  

Microsoft Academic Search

OBJECTIVE: The findings of magnetic resonance and x-ray angiography were compared for assessment of coronary artery stenosis in this validation study. BACKGROUND: Magnetic resonance angiography of the coronary arteries has recently been described, but there has been no comparison with x-ray angiography of localisation or assessment of important characteristics of coronary stenosis. METHODS: A breath hold, segmented k-space, 2D gradient

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

1996-01-01

161

Whole-brain arterial spin labeling perfusion MR imaging in patients with acute stroke  

PubMed Central

Background and purpose Perfusion MRI can be used to identify patients with acute ischemic stroke that may benefit from reperfusion therapies. The risk of nephrogenic systemic fibrosis, however, limits the use of contrast agents. Our objective was to evaluate the ability of arterial spin labeling (ASL), an alternative non-invasive perfusion technique, to detect perfusion deficits compared with dynamic susceptibility contrast (DSC) perfusion imaging. Methods Consecutive patients referred for emergency assessment of suspected acute stroke within a seven-month period were imaged with both ASL and DSC perfusion MRI. Images were interpreted in a random order by two experts blinded to clinical information for image quality, presence of perfusion deficits and diffusion-perfusion mismatches. Results 156 patients were scanned with a median time of 5.6 (3.0–17.7) hours from last seen normal. Stroke diagnosis was clinically confirmed in 78 patients. ASL and DSC imaging were available in 64 of these patients. A perfusion deficit was detected with DSC in 39 of these patients; ASL detected 32 of these index perfusion deficits, missing 7 lesions. The median volume of the perfusion deficits as determined with DSC was smaller in patients which were evaluated as normal with ASL than in those with a deficit (median, interquartile range; 56 (10–116) vs. 114 (41–225) ml, p=0.01). Conclusions ASL can depict large perfusion deficits and perfusion/diffusion mismatches in correspondence with DSC. Our findings show that a fast 2½ minute ASL perfusion scan may be adequate for screening acute stroke patients with contraindications to gadolinium-based contrast agents.

Bokkers, Reinoud P.H.; Hernandez, Daymara A.; Merino, Jose G.; Mirasol, Raymond V.; van Osch, M.J.; Hendrikse, Jeroen; Warach, Steven; Latour, Lawrence L.

2012-01-01

162

Magnetic resonance myocardial perfusion imaging in the diagnosis of functionally significant obstructive coronary artery disease: a systematic review protocol  

PubMed Central

Background Cardiac magnetic resonance (CMR) myocardial perfusion imaging has been suggested as a non-invasive alternative to pressure wire guided fractional flow reserve (FFR) in detecting haemodynamically significant obstructive coronary artery disease (CAD). The objective of this systematic review is to determine the diagnostic accuracy of CMR and to compare it to FFR. Methods/design A systematic review of diagnostic test accuracy of CMR and FFR will be conducted. Relevant English-language articles published before November 2013 in Medline, PubMed, EMBASE, Google scholar, Scopus and Cochrane databases will be identified. Relevant referenced articles from those selected will also be analysed. Articles describing diagnostic studies that compared CMR to FFR in patients with known or suspected coronary artery disease will be included. Two investigators will independently screen, assess quality and extract data from the selected articles. The Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool will be used to assess methodological quality. STATA 13 (the xtmelogit command) software will be used to calculate bivariate random effects models and estimate pooled sensitivity and specificity with 95% confidence intervals. Forests plots and summary receiver operating characteristics curves will also be generated. Sub-group pooled analyses using image quality of CMR (in terms of magnetic flux density - Tesla) and basis of analyses (coronary arterial territory vs. patients basis) at different FFR cutoffs (?0.75 and ?0.8) will also be performed. Discussion This systematic review will help to determine if CMR is an adequate alternative to FFR in the diagnosis of significant and obstructive CAD. We will also be able to assess diagnostic accuracy of specific types of CMR scan at different FFR cutoffs. Systematic review registration This systematic review had been registered at PROSPERO and the registration number is CRD42013006180.

2014-01-01

163

Identification, imaging, functional assessment and management of congenital coronary arterial abnormalities in children.  

PubMed

The coronary arteries, the vessels through which both substrate and oxygen are provided to the cardiac muscle, normally arise from paired stems, right and left, each arising from a separate and distinct sinus of the aortic valve. The right coronary artery runs through the right atrioventricular groove, terminating in the majority of instances in the inferior interventricular groove. The main stem of the left coronary artery bifurcates into the anterior descending, or interventricular, and the circumflex branches. Origin of the anterior descending and circumflex arteries from separate orifices from the left sinus of Valsalva occurs in about 1% of the population, while it is also frequent to find the infundibular artery arising as a separate branch from the right sinus of Valsalva. Anomalies of the coronary arteries can result from rudimentary persistence of an embryologic coronary arterial structure, failure of normal development or normal atrophy as part of development, or misplacement of connection of a an otherwise normal coronary artery. Anomalies, therefore, can be summarized in terms of abnormal origin or course, abnormal number of coronary arteries, lack of patency of the orifice of coronary artery, or abnormal connections of the arteries. Anomalous origin of the left coronary artery from the pulmonary trunk occurs with an incidence of approximately 1 in 300,000 children. The degree of left ventricular dysfunction produced likely relates to the development of collateral vessels that arise from the right coronary artery, and provide flow into the left system. Anomalous origin of either the right or the left coronary artery from the opposite sinus of Valsalva can be relatively innocuous, but if the anomalous artery takes an interarterial course between the pulmonary trunk and the aorta, this can underlie sudden death, almost invariably during or immediately following strenuous exercise or competitive sporting events. Distal anomalies of the coronary arteries most commonly involve abnormal connections, or fistulas, between the right or left coronary arterial systems and a chamber or vessel. We discuss the current techniques available for imaging these various lesions, along with their functional assessment, concluding with a summary of current strategies for management. PMID:18039399

Friedman, Alan H; Fogel, Mark A; Stephens, Paul; Hellinger, Jeffrey C; Nykanen, David G; Tweddell, James; Feltes, Timothy F; Rome, Jonathan J

2007-09-01

164

Multirater agreement on arthroscopic image quality.  

PubMed

In arthroscopy (minimally invasive orthopaedic surgery), the view is frequently disturbed. To optimize the view, quantification of the arthroscopic image quality is important. Thereto, disturbances were categorized as bleeding, air bubbles, turbidity (synovial fluid), loose fibrous tissue, and attached fibrous tissue, which cover the arthroscopic image area. The goal is to determine the percentages of disturbance coverage for which the view is acceptable. Thirty-two short films of the five disturbances were selected from arthroscopic knee procedures. The films showed disturbances covering different percentages of the image area. Thirty-nine orthopaedic surgeons were asked to judge whether or not the view of each film was acceptable. Multiple-choice questions on irrigation and disturbances were asked. A clear transition from acceptable to unacceptable view was found for bleeding (5 per cent of the covered area was acceptable; 25 per cent was not acceptable), and air bubbles (10 per cent was acceptable; 20 per cent was not acceptable). Loose fibrous tissue showed a gradual transition where 25 per cent was still accepted by a third of the surgeons. Turbidity and attached fibrous tissue were tolerated up to 50 per cent by half of the surgeons. Surgeons using a mechanical pump tolerated a lower percentage of synovial fluid (p<0.05). The most intolerable disturbance was bleeding. The results were consistent and will be used for computerized detection of disturbances. PMID:19278195

Tuijthof, G J M; Abbink, M; Sierevelt, I N; van Dijk, C N

2009-02-01

165

Quality control of diffusion weighted images  

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

166

Quality Control of Diffusion Weighted Images  

PubMed Central

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

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

2013-01-01

167

Perceptual assessment of image quality in multimedia technology  

Microsoft Academic Search

Fast development of multimedia technology during the last two decades has brought different approach to the evaluation of image quality. In most of the cases, multimedia technology applications do not rely on the image fidelity criterion but the human impression plays the main role. A model for perceptual assessment of image quality in multimedia technology is presented in this paper.

Karel Fliegel

2007-01-01

168

A multistage perceptual quality assessment for compressed digital angiogram images  

Microsoft Academic Search

This paper describes a multistage perceptual quality assessment (MPQA) model for compressed images. The motivation for the development of a perceptual quality assessment is to measure (in)visible differences between original and processed images. The MPQA produces visible distortion maps and quantitative error measures informed by considerations of the human visual system (HVS). Original and decompressed images are decomposed into different

Joonmi Oh; Sandra I. Woolley; Theodoros N. Arvanitis; John N. Townend

2001-01-01

169

Image quality assessment: from error visibility to structural similarity  

Microsoft Academic Search

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

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

2004-01-01

170

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

NASA Astrophysics Data System (ADS)

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

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

2009-02-01

171

Note: A multifunction lens test system for imaging quality evaluation  

Microsoft Academic Search

A novel multifunction lens imaging quality test system is established to overcome the practical problems in the conventional system. This system is compact, cost efficient, user friendly, and suitable for lens quality control in production line. The established system can evaluate the modulation transform function, imaging depth, image distortion, and light intensity distribution of the tested lens by auto-changing the

Chun-Jen Chen; Wen-Hong Wu; Kuo-Cheng Huang

2010-01-01

172

Image quality assessment method in intelligent transportation systems  

Microsoft Academic Search

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,

Bangping Wang; Jian You; Yijun Xiao; Feng Wang

2007-01-01

173

Minimum average-cost path for real time 3D coronary artery segmentation of CT images.  

PubMed

In this paper, we propose a Minimum Average-cost Path (MACP) model for segmenting 3D coronary arteries by minimizing the average edge cost along path in discrete 4D graph constructed by image voxels and associated radii. Prim's Minimum Spanning Tree method is used for efficient optimization of the MACP model. The centerline and the radii of the cross sections of the coronary artery are extracted simultaneously during the optimization. The method does not need any image preprocessing steps and has been intensively validated as an effective approach with the Rotterdam Coronary Artery Algorithm Evaluation Framework. The computational cost of the proposed method is particularly low (7.467 seconds per segment, 18.5mm/s on average), which makes real time segmentation of coronary artery possible. Shortcut problem, which is a classic issue of the minimal path techniques, can also be overcome by the proposed method. PMID:22003729

Zhu, Ning; Chung, Albert C S

2011-01-01

174

Artery-vein separation via MRA--an image processing approach.  

PubMed

This paper presents a near-automatic process for separating vessels from background and other clutter as well as for separating arteries and veins in contrast-enhanced magnetic resonance angiographic (CE-MRA) image data, and an optimal method for three-dimensional visualization of vascular structures. The separation process utilizes fuzzy connected object delineation principles and algorithms. The first step of this separation process is the segmentation of the entire vessel structure from the background and other clutter via absolute fuzzy connectedness. The second step is to separate artery from vein within this entire vessel structure via iterative relative fuzzy connectedness. After seed voxels are specified inside artery and vein in the CE-MRA image, the small regions of the bigger aspects of artery and vein are separated in the initial iterations, and further detailed aspects of artery and vein are included in later iterations. At each iteration, the artery and vein compete among themselves to grab membership of each voxel in the vessel structure based on the relative strength of connectedness of the voxel in the artery and vein. This approach has been implemented in a software package for routine use in a clinical setting and tested on 133 CE-MRA studies of the pelvic region and two studies of the carotid system from six different hospitals. In all studies, unified parameter settings produced correct artery-vein separation. When compared with manual segmentation/separation, our algorithms were able to separate higher order branches, and therefore produced vastly more details in the segmented vascular structure. The total operator and computer time taken per study is on the average about 4.5 min. To date, this technique seems to be the only image processing approach that can be routinely applied for artery and vein separation. PMID:11513021

Lei, T; Udupa, J K; Saha, P K; Odhner, D

2001-08-01

175

A Study of Stereoscopic Image Quality Assessment Model Corresponding to Disparate Quality of Left/Right Image for JPEG Coding  

NASA Astrophysics Data System (ADS)

Our research is focused on examining a stereoscopic quality assessment model for stereoscopic images with disparate quality in left and right images for glasses-free stereo vision. In this paper, we examine the objective assessment model of 3-D images, considering the difference in image quality between each view-point generated by the disparity-compensated coding. A overall stereoscopic image quality can be estimated by using only predicted values of left and right 2-D image qualities based on the MPEG-7 descriptor information without using any disparity information. As a result, the stereoscopic still image quality is assessed with high prediction accuracy with correlation coefficient=0.98 and average error=0.17.

Sato, Masaharu; Horita, Yuukou

176

Classification algorithm of pulmonary vein and artery based on multi-slice CT image  

NASA Astrophysics Data System (ADS)

Recently, multi-slice helical CT technology was developed. Unlike the conventional helical CT, we can obtain CT images of two or more slices with 1 time scan. Therefore, we can get many pictures with a clear contrast images and thin slice images in one time of scanning. The purpose of this presentation is to evaluate the proposed automatic extraction bronchus and pulmonary vein and artery on multi-slice CT images. The bronchus is extracted by application with region growing technique and the morphological filters, 3D distance transformation. These results indicate that the proposed algorithm provides the ability to accurately develop an automatic extraction algorithm of the bronchus on multi-slice CT images. In this report, we used pulmonary vein and artery marked by the doctor, It aims to discover an amount of the feature necessary for classifying the pulmonary vein and artery by using the anatomical feature. The classification of the pulmonary vein and artery is thought necessary information that it is state of tuber benign or malignity judgment. It is very important to separate the contact part of the lung blood vessel in classifying pulmonary vein and artery. Then, it aims to discover the feature of the contact part of the lung blood vessel in this report.

Yonekura, Taihei; Matsuhiro, Mikio; Saita, Shinsuke; Kubo, Mitsuru; Kawata, Yoshiki; Niki, Noboru; Nishitani, Hiromu; Ohmatsu, Hironobu; Kakinuma, Ryutaro; Moriyama, Noriyuki

2007-03-01

177

Practical guidelines for radiographers to improve computed radiography image quality  

PubMed Central

Computed Radiography (CR) has become a major digital imaging modality in a modern radiological department. CR system changes workflow from the conventional way of using film/screen by employing photostimulable phosphor plate technology. This results in the changing perspectives of technical, artefacts and quality control issues in radiology departments. Guidelines for better image quality in digital medical enterprise include professional guidelines for users and the quality control programme specifically designed to serve the best quality of clinical images. Radiographers who understand technological shift of the CR from conventional method can employ optimization of CR images. Proper anatomic collimation and exposure techniques for each radiographic projection are crucial steps in producing quality digital images. Matching image processing with specific anatomy is also important factor that radiographers should realise. Successful shift from conventional to fully digitised radiology department requires skilful radiographers who utilise the technology and a successful quality control program from teamwork in the department.

Pongnapang, N

2005-01-01

178

Imaging of traumatic arterial injuries in the neck with an emphasis on CTA  

Microsoft Academic Search

Arterial injuries in the neck may be secondary to blunt or penetrating trauma. Because of clinical difficulties in early identification\\u000a of these injuries as well as their potentially catastrophic consequences, imaging is indispensible in the diagnosis of arterial\\u000a injuries in the neck. Computed tomography angiography (CTA) has become the initial study of choice in management of these\\u000a patients. We review

Jason W. Schroeder; Visveshwar Baskaran; Nafi Aygun

2010-01-01

179

Strangulation of aberrant artery in extralobar pulmonary sequestration on video imaging.  

PubMed

We report a case of an 18-year old female patient with symptomatic extralobar pulmonary sequestration. The initial symptom was sudden-onset right lateral abdominal pain. Enhanced computed tomography showed a 5 cm in diameter, spindle-shaped mass located in the costophrenic sinus with no aberrant artery. Exploratory thoracoscopy showed a haemorrhagic mass caused by strangulation of an aberrant vessel originating from the intercostal artery. Pathological findings revealed pulmonary sequestration with haemorrhagic infarction. The strangulated aberrant artery was clearly demonstrated by video imaging. PMID:24729200

Nakano, Tomoyuki; Tetsuka, Kenji; Yamamoto, Shinichi; Endo, Shunsuke

2014-08-01

180

Detecting Hepatocellular Carcinoma: Value of Unenhanced or Arterial Phase CT Imaging or Both Used in Conjunction with Conventional Portal Venous Phase Contrast Enhanced CT Imaging  

Microsoft Academic Search

OBJECTIVE. Because rates of detection of hypervascular neoplasms by conventional dynamic incremental-bolus CT are lower than rates of detection of hypovascular tumors by ?::?and because both unenhanced CT imaging and arterial phase helical CT imaging may increase the detection of hypervascular tumors, such as hepatocellular carcinoma, we eval- uated the value of unenhanced and arterial phase CT imaging used in

James H. Oliver; Richard L Baron; Michael P. Federle; Howard E. Rockette

181

Enhancement Characteristics and Impact on Image Quality of Two Gadolinium Chelates at Equimolar Doses for Time-Resolved 3-Tesla MR-Angiography of the Calf Station  

PubMed Central

Purpose To compare enhancement characteristics and image quality of two macrocyclic gadolinium chelates, gadoterate meglumine and gadobutrol, in low-dose, time-resolved MRA of the calf station. Materials and Methods 100 consecutive patients with peripheral arterial disease (stages II-IV) were retrospectively analysed. Fifty patients were included in each group - 32 men and 18 women for gadobutrol (mean age 67 years) and 34 men, 16 women for gadoterate meglumine (mean age 64 years). 0.03 mmol/kg bw of either gadobutrol or gadoterate meglumine was injected. Gadobutrol was diluted 1?1 with normal saline (0.9% NaCl) to provide similar injection volume and bolus geometry compared to the undiluted 0.5 M dose of gadoterate meglumine. Signal-to-noise-ratio (SNR), contrast-to-noise-ratio (CNR) and image quality were analysed and compared between the two groups. Results Mean SNR ranged from 83.0±46.7 (peroneal artery) to 96.4±64.5 (anterior tibial artery) for gadobutrol, and from 37.6±13.8 (peroneal artery) to 45.3±16.4 (anterior tibial artery) for the gadoterate meglumine group (p<0.0001). CNR values ranged from 30.1±20.1 (peroneal artery) to 37.6±26.0 (anterior tibial artery) for gadobutrol and from 14.9±8.0 (peroneal artery) to 18.6±16.4 (anterior tibial artery) for gadoterate meglumine (p<0.0001). No significant difference in image quality was found except for the peroneal arteries (p?=?0.006 and p?=?0.04). Interreader agreement was excellent (kappa 0.87–0.93) Conclusion The significantly better enhancement as assessed by SNR and CNR provided by gadobutrol compared to gadoterate meglumine does not translate into substantial differences in image quality in an equimolar, low-dose, time-resolved MRA protocol of the calves.

Hansmann, Jan; Michaely, Henrik J.; Morelli, John N.; Luckscheiter, Andre; Schoenberg, Stefan O.; Attenberger, Ulrike I.

2014-01-01

182

Object matching task-oriented image quality assessment  

NASA Astrophysics Data System (ADS)

As the development of Automatic Target Recognition (ATR) technology, the performance evaluation for it becomes more and more important. Image Quality is a very important part of ATR performance evaluation. Whether the image quality is good or bad is tightly related with algorithm performance. In this paper, we construct a system of image quality assessment related to object matching task. In our framework, image quality measures published and newly proposed are analyzed first, and then a set of effective measures are selected from above. At last, we construct a model of relationship between selected measures and matching. Given an image, the system will indicate whether an image is suitable for a specific matching task. Gray level correlation matching and histograms of oriented gradients -matching are demonstrated and their experimental result shows that the image quality assessment system works effectively.

Cao, Zhiguo; Duan, Xiyao

2011-11-01

183

Risk-Adjusted Survival after Coronary Artery Bypass Grafting: Implications for Quality Improvement  

PubMed Central

Mortality represents an important outcome measure following coronary artery bypass grafting. Shorter survival times may reflect poor surgical quality and an increased number of costly postoperative complications. Quality control efforts aimed at increasing survival times may be misleading if not properly adjusted for case-mix severity. This paper demonstrates how to construct and cross-validate efficiency-outcome plots for a specified time (e.g., 6-month and 1-year survival) after coronary artery bypass grafting, accounting for baseline cardiovascular risk factors. The application of this approach to regional centers allows for the localization of risk stratification rather than applying overly broad and non-specific models to their patient populations.

Efird, Jimmy T.; O'Neal, Wesley T.; Davies, Stephen W.; O'Neal, Jason B.; Kindell, Linda C.; Anderson, Curtis A.; Chitwood, W. Randolph; Ferguson, T. Bruce; Kypson, Alan P.

2014-01-01

184

Information Content Weighting for Perceptual Image Quality Assessment  

Microsoft Academic Search

Many state-of-the-art perceptual image quality as- sessment (IQA) algorithms share a common two-stage structure: local quality\\/distortion measurement followed by pooling. While significant progress has been made in measuring local image quality\\/distortion, the pooling stage is often done in ad-hoc ways, lacking theoretical principles and reliable computational models. This paper aims to test the hypothesis that when viewing natural images, the

Zhou Wang; Qiang Li

2011-01-01

185

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

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

186

Retinal Image Quality during Accommodation in Adult Myopic Eyes  

PubMed Central

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.

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

2014-01-01

187

Food quality assessment by NIR hyperspectral imaging  

NASA Astrophysics Data System (ADS)

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.

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

2010-04-01

188

The use of the general image quality equation in the design and evaluation of imaging systems  

Microsoft Academic Search

The design of any modern imaging system is the end result of many trade studies, each seeking to optimize image quality within real world constraints such as cost, schedule and overall risk. The National Imagery Interpretability Rating Scale (NIIRS) is a useful measure of image quality, because, by characterizing the overall interpretability of an image, it combines into one metric

Steve A. Cota; Christopher J. Florio; David J. Duvall; Michael A. Leon

2009-01-01

189

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

PubMed Central

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

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

2011-01-01

190

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

191

Influence of image acquisition settings on radiation dose and image quality in coronary angiography by 320-detector volume computed tomography: the CORE320 pilot experience  

PubMed Central

The objective of this study was to investigate the impact of image acquisition settings and patients' characteristics on image quality and radiation dose for coronary angiography by 320-row computed tomography (CT). CORE320 is a prospective study to investigate the diagnostic performance of 320-detector CT for detecting coronary artery disease and associated myocardial ischemia. A run-in phase in 65 subjects was conducted to test the adequacy of the computed tomography angiography (CTA) acquisition protocol. Tube current, exposure window, and number of cardiac beats per acquisition were adjusted according to subjects' gender, heart rate, and body mass index (BMI). Main outcome measures were image quality, assessed by contrast/noise measurements and qualitatively on a 4-point scale, and radiation dose, estimated by the dose-length-product. Average heart rate at image acquisition was 55.0±7.3 bpm. Median Agatston calcium score was 27.0 (interquartile range 1–330). All scans were prospectively triggered. Single heart beat image acquisition was obtained in 61 of 65 studies (94%). Sixty-one studies (94%) and 437 of 455 arterial segments (96%) were of diagnostic image quality. Estimated radiation dose was significantly greater in obese (5.3±0.4 mSv) than normal weight (4.6±0.3 mSv) or overweight (4.7±0.3 mSv) subjects (P<0.001). BMI was the strongest factor influencing image quality (odds ratio=1.457, P=0.005). The CORE320 CTA image acquisition protocol achieved a good balance between image quality and radiation dose for a 320-detector CT system. However, image quality in obese subjects was reduced compared to normal weight subjects, possibly due to tube voltage/current restrictions mandated by the study protocol.

Yoneyama, Kihei; Vavere, Andrea L.; Cerci, Rodrigo; Ahmed, Rukhsar; Arai, Andrew E.; Niinuma, Hiroyuki; Rybicki, Frank J.; Rochitte, Carlos E.; Clouse, Melvin E.; George, Richard T.; Lima, Joao A.C.; Arbab-Zadeh, Armin

2012-01-01

192

Limitations to adaptive optics image quality in rodent eyes  

PubMed Central

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

Zhou, Xiaolin; Bedggood, Phillip; Metha, Andrew

2012-01-01

193

Image quality assessment method in intelligent transportation systems  

NASA Astrophysics Data System (ADS)

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.

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

2007-11-01

194

Limitations to adaptive optics image quality in rodent eyes.  

PubMed

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

Zhou, Xiaolin; Bedggood, Phillip; Metha, Andrew

2012-08-01

195

Quality assessment of images illuminated by dim LCD backlight  

NASA Astrophysics Data System (ADS)

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.

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

2012-02-01

196

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

NASA Astrophysics Data System (ADS)

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

Richards, Kent L.; Cannon, Scott R.

1990-08-01

197

Quantitative quality control in microarray image processing and data acquisition  

Microsoft Academic Search

A new integrated image analysis package with quanti- tative quality control schemes is described for cDNA microarray technology. The package employs an itera- tive algorithm that utilizes both intensity characteristics and spatial information of the spots on a microarray image for signal-background segmentation and defines five quality scores for each spot to record irreg- ularities in spot intensity, size and

Xujing Wang; Soumitra Ghosh; Sun-Wei Guo

2001-01-01

198

Comparison of SNR image quality metrics for remote sensing systems  

Microsoft Academic Search

Different definitions of the signal-to-noise ratio (SNR) are being used as metrics to describe the image quality of remote sensing systems. It is usually not clear which SNR definition is being used and what the image quality of the system is when an SNR value is quoted. This paper looks at several SNR metrics used in the remote sensing community.

Robert D. Fiete; Theodore A. Tantalo

2001-01-01

199

Image-based modeling of the hemodynamics in cerebral arterial trees  

NASA Astrophysics Data System (ADS)

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.

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

2009-02-01

200

Comparison between the image quality of multisegment and halfscan reconstructions of non-invasive CT coronary angiography  

PubMed Central

The purpose of this study was to compare the image quality of multisegment and halfscan reconstructions of multislice computed tomography (MSCT) coronary angiography. 126 patients with suspected coronary artery disease and uninfluenced heart rates were examined by 16-slice CT before they underwent invasive coronary angiography. Multisegment and halfscan reconstructions were performed in all patients, and subjective image quality, overall vessel length, vessel length free of motion artefacts and contrast-to-noise ratios (CNRs) were compared for both techniques. The diagnostic accuracy of both approaches was compared with the results of invasive coronary angiography. Overall image quality scores of multisegment reconstruction were superior to those of halfscan reconstruction (13.3±2.1 vs 11.9±2.9; p<0.001). Multisegment reconstruction depicted significantly longer overall coronary vessel lengths (p<0.001) and larger vessel proportions free of motion artefacts in three of the four main coronary arteries. CNRs in the left main, left anterior descending and left circumflex coronary arteries were significantly higher when multisegment reconstruction was used (p<0.001). Overall accuracy was higher for multisegment reconstruction compared with halfscan reconstruction (87% vs 62%). In conclusion, multisegment reconstruction significantly improves image quality and diagnostic accuracy of MSCT coronary angiography compared with standard halfscan reconstruction, resulting in vessel lengths depicted free of motion comparable to those of CT performed in patients given ?-blockers to lower heart rates.

Schnapauff, D; Teige, F; Hamm, B; Dewey, M

2009-01-01

201

Carotid Artery Stenosis: Optimization of CT Angiography with a Combination of Shaded Surface Display and Source Images  

Microsoft Academic Search

PURPOSE: To evaluate the accuracy of CT angiography of occlusive disease of the carotid arteries using three-dimensional surface-rendered images alone and in conjunction with display of axial source images. METHODS: Forty-eight symptomatic patients had conventional angiography followed by CT angiography within 24 hours. Images of 96 carotid arteries were acquired using contrast-enhanced spiral CT. Image postprocessing was performed on a

Zsuzsanna Papp; Mahendra Patel; Manzar Ashtari; Masashi Takahashi; Jacques Goldstein; William Maguire; Peter G. Herman

1997-01-01

202

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

NASA Astrophysics Data System (ADS)

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.

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

2009-02-01

203

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

PubMed

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

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

2014-05-01

204

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

PubMed Central

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.

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

2013-01-01

205

Color image quality assessment combining saliency and FSIM  

NASA Astrophysics Data System (ADS)

Saliency is an important feature of human visual attention. Salient regions of an image immediately attract our attention. Therefore, attention to salient regions is an important attribute to measure image qualities. A novel image quality metric is proposed in this paper, in which salient regions are extracted and the use of FSIM (Feature SIMilarity) in these regions is analyzed for image quality assessment. Experimental results for a set of intuitive examples with different distortion types demonstrate that the improved FSIM can achieve a better performance than the original form.

Li, Ang; She, Xiaochun; Sun, Qizhi

2013-07-01

206

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

NASA Astrophysics Data System (ADS)

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

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

2004-04-01

207

FLIR image quality assessment for gray scale template matching  

NASA Astrophysics Data System (ADS)

Infrared image quality assessment plays an important role in FLIR. In this paper, infrared image quality assessment specified in gray scale template matching was studied. Target local salient metric (LSM) and global salient metric (GSM) were presented as quality indices, and Back-Propagation network was adopted to integrate the indices. Experiment shows that error caused by the proposed method is less than the error caused by the classical indices, such as ETB and TIR.

Wang, Peng; Sun, Ji-Yin; Ju, Xi-Nuo

2011-11-01

208

Image processing system performance prediction and product quality evaluation  

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

209

Localized Iris Image Quality Using 2-D Wavelets  

Microsoft Academic Search

The performance of an iris recognition system can be undermined by poor quality im- ages and result in high false reject rates (FRR) and failure to enroll (FTE) rates. In this paper, a wavelet-based quality measure for iris images is proposed. The merit of the this approach lies in its ability to deliver good spatial adaptivity and determine local quality

Yi Chen; Sarat C. Dass; Anil K. Jain

2006-01-01

210

Image Quality Assessment Based on Intrinsic Mode Function Coefficients Modeling  

Microsoft Academic Search

\\u000a Reduced reference image quality assessment (RRIQA) methods aim to assess the quality of a perceived image with only a reduced\\u000a cue from its original version, called ”reference image”. The powerful advantage of RR methods is their ”General-purpose”.\\u000a However, most introduced RR methods are built upon a non-adaptive transform models. This can limit the scope of RR methods\\u000a to a small

Abdelkaher Ait Abdelouahad; Mohammed El Hassouni; Hocine Cherifi; Driss Aboutajdine

211

Image quality enhancement in AMOLED microdisplay for mobile projectors  

Microsoft Academic Search

Data driving techniques and circuits to enhance the image quality of the 0.4-inch diagonal VGA AMOLED on silicon substrate have been proposed. The uniformity of a displayed image can be severely degraded by the random offset voltages of the data drivers. The color shift due to the differential OLED material aging is another well-known concern. To alleviate these image quality

Byong-Deok Choi; In-Su Park; Jong-Seok Kim; Sung-Jin Lee; Byung Bae

2011-01-01

212

Effect of image quality on calcification detection in digital mammography  

SciTech Connect

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.

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

213

Evaluating the Mechanical Behavior of Arterial Tissue using Digital Image Correlation  

Microsoft Academic Search

In this study, digital image correlation (DIC) was adopted to examine the mechanical behavior of arterial tissue from bovine aorta. Rectangular sections comprised of the in- timal and medial layers were excised from the descending aorta and loaded in displacement control uniaxial tension up to 40 percent elongation. Specimens of silicon rubber sheet were also prepared and served as a

Dongsheng Zhang; Charles D. Eggleton; Dwayne D. Arola

2002-01-01

214

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

PubMed Central

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

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

1999-01-01

215

Arterial Vulnerable Plaque Characterization Using Ultrasound-Induced Thermal Strain Imaging (TSI)  

Microsoft Academic Search

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

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

2008-01-01

216

(Shear) Strain Imaging Used in Noninvasive Detection of Vulnerable Plaques in the Carotid Arterial Wall  

Microsoft Academic Search

\\u000a The primary trigger for myocardial infarction and stroke is destabilization of atherosclerotic plaques. The chance of a plaque\\u000a to rupture is related to its composition and geometry. Ultrasound (shear) strain imaging allows assessment of local tissue\\u000a mechanics and possible risk assessment of vulnerable plaques. Intravascularly, in coronary arteries using a catheter, strain\\u000a imaging has been demonstrated to be successful. At

T. Idzenga; H. H. G. Hansen; C. L. Korte

217

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

218

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

PubMed Central

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.

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

2014-01-01

219

Surface roughness detection of arteries via texture analysis of ultrasound images for early diagnosis of atherosclerosis.  

PubMed

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

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

2013-01-01

220

3D GRASE PROPELLER: Improved Image Acquisition Technique for Arterial Spin Labeling Perfusion Imaging  

PubMed Central

Arterial spin labeling (ASL) is a non-invasive technique that can quantitatively measure cerebral blood flow (CBF). While traditionally ASL employs 2D EPI or spiral acquisition trajectories, single-shot 3D GRASE is gaining popularity in ASL due to inherent SNR advantage and spatial coverage. However, a major limitation of 3D GRASE is through-plane blurring caused by T2 decay. A novel technique combining 3D GRASE and a PROPELLER trajectory (3DGP) is presented to minimize through-plane blurring without sacrificing perfusion sensitivity or increasing total scan time. Full brain perfusion images were acquired at a 3×3×5mm3 nominal voxel size with Q2TIPS-FAIR as the ASL preparation sequence. Data from 5 healthy subjects was acquired on a GE 1.5T scanner in less than 4 minutes per subject. While showing good agreement in CBF quantification with 3D GRASE, 3DGP demonstrated reduced through-plane blurring, improved anatomical details, high repeatability and robustness against motion, making it suitable for routine clinical use.

Tan, Huan; Hoge, W. Scott; Hamilton, Craig A.; Gunther, Matthias; Kraft, Robert A.

2014-01-01

221

Meat quality evaluation by hyperspectral imaging technique: an overview.  

PubMed

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

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

2012-01-01

222

The role of completion imaging following carotid artery endarterectomy.  

PubMed

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

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

2013-05-01

223

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

SciTech Connect

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

Chapman, D. [Brookhaven National Laboratory, Upton, NY (United States); Schulze, C. [ESRF, Grenoble (France)

1994-05-01

224

Microoptical components for enhancing the image quality of transflective LCDs  

Microsoft Academic Search

In this paper, we presented two micro-optical structures, image-enhanced reflector and random grating reflector, to enhance the image quality of transflective LCDs under both bright and dark ambience conditions. The image-enhanced reflector for the transflective LCD has been fabricated using a gray-tone mask exposed by excimer laser. The width of the image-enhanced reflector is 16 ?m and the depth is

Han-Ping David Shieh; Yi-Pai Huang; Mu-Jen Su; S.-T. Wu

2003-01-01

225

Robust extraction of the aorta and pulmonary artery from 3D MDCT image data  

NASA Astrophysics Data System (ADS)

Accurate definition of the aorta and pulmonary artery from three-dimensional (3D) multi-detector CT (MDCT) images is important for pulmonary applications. This work presents robust methods for defining the aorta and pulmonary artery in the central chest. The methods work on both contrast enhanced and no-contrast 3D MDCT image data. The automatic methods use a common approach employing model fitting and selection and adaptive refinement. During the occasional event that more precise vascular extraction is desired or the method fails, we also have an alternate semi-automatic fail-safe method. The semi-automatic method extracts the vasculature by extending the medial axes into a user-guided direction. A ground-truth study over a series of 40 human 3D MDCT images demonstrates the efficacy, accuracy, robustness, and efficiency of the methods.

Taeprasartsit, Pinyo; Higgins, William E.

2010-03-01

226

A comparison of Power Doppler with conventional sonographic imaging for the evaluation of renal artery stenosis  

PubMed Central

Background Power Doppler (PD) has improved diagnostic capabilities of vascular sonography, mainly because it is independent from the angle of insonation. We evaluated this technique in a prospective comparison with conventional imaging, consisting in Duplex and Color Doppler, for the evaluation of Renal Artery (RA) stenosis. Methods Sensitivity, specificity and predictive values of PD and conventional imaging were assessed in a blinded fashion on eighteen patients, 9 with angiographic evidence of unilateral RA stenosis (hypertensive patients) and 9 with angiographically normal arteries (control group). PD images were interpreted with an angiography-like criteria. Results In the control group both techniques allowed correct visualization of 16 out of the 18 normal arteries (93% specificity). Only in five hypertensive patients RA stenosis was correctly identified with conventional technique (56% sensitivity and 86% negative predictive value); PD was successful in all hypertensive patients (100% sensitivity and negative predictive value), since the operators could obtain in each case of RA stenosis a sharp color signal of the whole vessel with a clear "minus" at the point of narrowing of the lumen. All results were statistically significant (p < 0.01). Conclusions This study demonstrates that PD is superior to conventional imaging, in terms of sensitivity and specificity, for the diagnosis of RA stenosis, because it allows a clear visualization of the whole stenotic vascular lumen. Especially if it is used in concert with the other sonographic techniques, PD can enable a more accurate imaging of renovascular disease with results that seem comparable to selective angiography.

Manganaro, Agatino; Ando', Giuseppe; Salvo, Antonino; Consolo, Andrea; Coppolino, Frank; Giannino, Domenico

2004-01-01

227

Figure of Image Quality and Information Capacity in Digital Mammography  

PubMed Central

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.

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

2014-01-01

228

Improvement of image quality by polarization mixing  

NASA Astrophysics Data System (ADS)

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

Kasahara, Ryosuke; Itoh, Izumi; Hirai, Hideaki

2014-03-01

229

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

NASA Astrophysics Data System (ADS)

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).

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

230

Atherosclerosis imaging and calcified plaque: coronary artery disease risk assessment  

Microsoft Academic Search

Over the last decade, there has been increased recognition that atherosclerosis imaging adds greatly to the ability to identify patients at high risk for cardiac events. Technologies such as electron beam computed tomography and carotid intimal media thickness have contributed significantly to our understanding of the prevalence of preclinical atherosclerosis and its consequences. Guidelines and policy toward these modalities have

Matthew J Budoff

2003-01-01

231

Determinants of an impaired quality of life five years after coronary artery bypass surgery  

PubMed Central

OBJECTIVE—To identify determinants of an inferior quality of life (QoL) five years after coronary artery bypass grafting (CABG).?SETTING—University hospital.?PARTICIPANTS—Patients from western Sweden who underwent CABG between 1988 and 1991.?MAIN OUTCOME MEASURES—Questionnaires for evaluating QoL before CABG and five years after operation. Three different instruments were used: the Nottingham health profile (NHP), the psychological general wellbeing index (PGWI), and the physical activity score (PAS).?RESULTS—2121 patients underwent CABG, of whom 310 died during five years' follow up. Information on QoL after five years was available in 1431 survivors (79%). There were three independent predictors for an inferior QoL with all three instruments: female sex, a history of diabetes mellitus, and a history of chronic obstructive pulmonary disease. Multivariate analysis showed that a poor preoperative QoL was a strong independent predictor for an impaired QoL five years after CABG. An impaired QoL was also predicted by previous disease.?CONCLUSIONS—Female sex, an impaired QoL before surgery, and other diseases such as diabetes mellitus are independent predictors for an impaired QoL after CABG in survivors five years after operation.?? Keywords: coronary artery bypass surgery; predictors; quality of life

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

1999-01-01

232

Quality assurance in digital dental imaging: a systematic review.  

PubMed

Abstract Objectives. Doses induced by individual dental examinations are low. However, dental radiography accounts for nearly one third of the total number of radiological examinations in the European Union. Therefore, special attention is needed with regard to radiation protection. In order to lower patient doses, the staff performing dental examinations must have competence in imaging as well as in radiation protection issues. This paper presents a systematic review about the core competencies needed by the healthcare staff in performing digital dental radiological imaging quality assurance. Materials and methods. The following databases were searched: Pubmed, Cinahl, Pro Quest and IEEXplore digital library. Also volumes of some dental imaging journals and doctoral theses of the Finnish universities educating dentists were searched. The search was performed using both MeSH terms and keywords using the option 'search all text'. The original keywords were: dental imaging, digital, x-ray, panoramic, quality, assurance, competence, competency, skills, knowledge, radiographer, radiologist technician, dentist, oral hygienist, radiation protection and their Finnish synonyms. Results. Core competencies needed by the healthcare staff performing digital dental radiological imaging quality assurance described in the selected studies were: management of dental imaging equipment, competence in image quality and factors associated with it, dose optimization and quality assurance. Conclusions. In the future there will be higher doses in dental imaging due to increasing use of CBCT and digital imaging. The staff performing dental imaging must have competence in dental imaging quality assurance issues found in this review. They also have to practice ethical radiation safety culture in clinical practice. PMID:24074393

Metsälä, Eija; Henner, Anja; Ekholm, Marja

2014-07-01

233

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.

234

Digital Receptor Image Quality Evaluation: Effect of Different Filtration Schemes  

NASA Astrophysics Data System (ADS)

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.

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

2010-04-01

235

Image Quality and Detection Performance of Military Photo Interpreters.  

National Technical Information Service (NTIS)

Student military interpreters viewed nine vertical aerial photographs to judge their interpretability and to answer questions concerning their contents. Image quality was manipulated to produce 32 levels of degradation for each of the nine scenes. A singl...

C. L. Elworth C. L. Klingberg C. R. Filleau

1970-01-01

236

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  

Microsoft Academic Search

Purpose  To evaluate the clinical outcome for uterine adenomyosis with or without uterine leiomyomata 40 months after uterine artery\\u000a embolization (UAE).\\u000a \\u000a \\u000a \\u000a \\u000a Methods  Forty women aged 39–56 years (median 46 years) with symptomatic uterine adenomyosis and magnetic resonance imaging findings\\u000a of uterine adenomyosis with or without combined uterine leiomyomata underwent UAE. Self-perceived changes in clinical symptoms\\u000a were assessed, and residual symptom severity and health-related quality of

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

237

Influence of chroma variations on naturalness and image quality of stereoscopic images  

NASA Astrophysics Data System (ADS)

The computational view on image quality of Janssen and Blommaert states that the quality of an image is determined by the degree to which the image is both useful (discriminability) and natural (identifiability). This theory is tested by creating two manipulations. Firstly, multiplication of the chroma values of each pixel with a constant in the CIELab color space, i.e., chroma manipulation, is expected to increase only the usefulness by increasing the distances between the individual color points, enhancing the contrast. Secondly, introducing stereoscopic depth by varying the screen disparity, i.e., depth manipulation, is expected to increase both the usefulness and the naturalness. Twenty participants assessed perceived image quality, perceived naturalness and perceived depth of the manipulated versions of two natural scenes. The results revealed a small, yet significant shift between image quality and naturalness as a function of the chroma manipulation. In line with previous research, preference in quality was shifted to higher chroma values in comparison to preference in naturalness. Introducing depth enhanced the naturalness scores, however, in contrast to our expectations, not the image quality scores. It is argued that image quality is not sufficient to evaluate the full experience of 3D. Image quality appears to be only one of the attributes underlying the naturalness of stereoscopic images.

Kuijsters, Andre; Ijsselsteijn, Wijnand A.; Lambooij, Marc T. M.; Heynderickx, Ingrid E. J.

2009-02-01

238

Fundamental image quality parameters of poroelastography  

Microsoft Academic Search

Poroelastography is an emerging elastographic technique that aims at imaging the temporal mechanical behavior of fluid-filled tissues. While standard elastographic methods focus primarily on the visualization of soft and hard tissue regions as being indicative of tissue pathological changes, poroelastography allows imaging several novel parameters that are related to the tissue’s effective compressibility and permeability. Medical areas where poroelastography could

Raffaella Righetti; Anuj Chaudhry; Sanjay Nair

2011-01-01

239

Image Quality Assessment of Sparse Aperture Designs  

Microsoft Academic Search

Increasing the available imaging time of a remote sensing satellite over a specified ground area can be accomplished by placing the satellite in a higher, more elliptical orbit. This, however, will also require the satellite to be farther away from the Earth, thus reducing the resolution of the images. If the aperture size of the optics can be increased proportional

Robert Fiete; Theodore Tantalo; Jason Calus; James Mooney

2000-01-01

240

Image quality assessment using the singular value decomposition theorem  

Microsoft Academic Search

In objective image quality metrics, one of the most important factors is the correlation of their results with the perceived\\u000a quality measurements. In this paper, a new method is presented based on comparing between the structural properties of the\\u000a two compared images. Based on the mathematical concept of the singular value decomposition (SVD) theorem, each matrix can\\u000a be factorized to

Azadeh Mansouri; Ahmad Mahmoudi Aznaveh; Farah Torkamani-Azar; J. Afshar Jahanshahi

2009-01-01

241

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

SciTech Connect

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.

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

242

Images of arterial tissues using catheter swept source optical coherence tomography  

NASA Astrophysics Data System (ADS)

Optical coherence tomography images of arterial samples harvested from asymptomatic pigs and from lipid-rich Watanabe heritable hyperlipidemic rabbits were acquired using a fiber catheter-based swept-source optical coherence tomography system (OCT). A quadrature Mach-Zehnder interferometer based on multi-port fiber couplers and a semiconductor optical amplifier (SOA) were employed in the swept-source optical coherence tomography system. The improvement of signal to noise ratio as a result of incorporating the SOA into the configuration translated in an increase of the penetration depth. A fiber probe ending in a fiber ball lens was developed for the arterial imaging. The images acquired by this system offer the possibility to investigate anatomical details located under the surface of the artery such as the intima, media, and adventitia layers (from lumen side) of the blood vessel wall , as well as morphological features specific to artherosclerotic plaques such as lipid pools, fibrous caps, macrophage accumulations and calcified. This report indicates that our improved catheter-based swept source OCT is a potential tool for in vivo intravascular imaging.

Mao, Youxin; Flueraru, Costel; Chang, Shoude; Popescu, Dan P.; Sowa, M. G.

2010-06-01

243

Effect of dose reduction on image quality and diagnostic performance in coronary computed tomography angiography.  

PubMed

To evaluate the effect of radiation dose reduction on image quality and diagnostic accuracy of coronary computed tomography (CT) angiography. Coronary CT angiography studies of 40 patients with (n = 20) and without (n = 20) significant (?50 %) stenosis were included (26 male, 14 female, 57 ± 11 years). In addition to the original clinical reconstruction (100 % dose), simulated images were created that correspond to 50, 25 and 12.5 % of the original dose. Image quality and diagnostic performance in identifying significant stenosis were determined. Receiver-operator-characteristics analysis was used to assess diagnostic accuracy at different dose levels. The identification of patients with significant stenosis decreased consistently at doses of 50, 25 and 12.5 of the regular clinical acquisition (100 %). The effect was relatively weak at 50 % dose, and was strong at dose levels of 25 and 12.5 %. At lower doses a steady increase was observed for false negative findings. The number of coronary artery segments that were rated as diagnostic decreased gradually with dose, this was most prominent for smaller segments. The area-under-the-curve (AUC) was 0.90 (p = 0.4) at 50 % dose; accuracy decreased significantly with 25 % (AUC 0.70) and 12.5 % dose (AUC 0.60) (p < 0.0001), with underestimation of patients having significant stenosis. The clinical acquisition protocol for evaluation of coronary artery stenosis with CT angiography represents a good balance between image quality and patient dose. A potential for a modest (<50 %) reduction of tube current might exist. However, more substantial reduction of tube current will reduce diagnostic performance of coronary CT angiography substantially. PMID:23001159

van der Bijl, Noortje; Joemai, Raoul M S; Mertens, Bart J A; de Roos, Albert; Veldkamp, Wouter J H; Bax, Jeroen J; Schuijf, Joanne D; Geleijns, Jacob; Kroft, Lucia J M

2013-02-01

244

Image quality evaluation with a new phase rotation beamformer.  

PubMed

Over the last few decades, dynamic focusing based on digital receive beamforming (DRBF) has led to significant improvements in image quality. However, it is computationally very demanding due to its requirement for multiple lowpass filters (e.g., a complex filter for each receive channel in quadrature demodulation-based phase rotation beamformers (QD-PRBF)). We recently developed a novel phase rotation beamformer with reduced complexity, which can lower: 1) the number of lowpass filters using 2-stage demodulation (TSD) and 2) the number of beamforming points using adap tive field-of-view (AFOV) imaging. In TSD, dynamic focusing is performed on the mixed signals, while sampling frequency of the beamformed signal (i.e., beamforming frequency) is adjusted based on the displayed field-of-view (FOV) size in AFOV imaging. In this paper, the image quality of the developed beamformer (i.e., TSD-AFOV-PRBF) has been quantitatively evaluated using phantom and in vivo data. From the phantom study, it was found that TSD-AFOV-PRBF with only 1024 beamforming points provides comparable image quality to QD-PRBF. We obtained a median contrast resolution (CR) degradation of 7.6% for the FOV size of 160 mm. Image quality steadily improves with FOV size reduction (e.g., 2.3% CR degradation at 85 mm). Similar results were also obtained from an in vivo study. Thus, TSD-AFOV-PRBF could provide comparable image quality to conventional beamformers at considerably reduced computational cost. PMID:18986891

Agarwal, Anup; Schneider, Fabio Kurt; Yoo, Yang Mo; Kim, Yongmin

2008-09-01

245

Fibroids Treated With Uterine Artery Embolization: Do Imaging Findings Correlate With Patient Outcomes?  

Microsoft Academic Search

Objective: To evaluate whether changes on ultrasound in uterine and fibroid volume and fibroid vascularity correlate with changes in symptom severity and health-related quality of life (HRQL) perceived by patients after uterine artery embolization (UAE). Materials and Methods: Sixty-four women (mean age 45.3) with symptomatic uterine fibroids underwent UAE at the Hysterectomy Alternatives (HAlt) clinic in Winnipeg, Manitoba. They completed

Noam Millo; Richard Boroditsky; Edward A. Lyons; Mature Women

2010-01-01

246

Regional aortic compliance studied by magnetic resonance imaging: the effects of age, training, and coronary artery disease  

Microsoft Academic Search

Arterial compliance was measured in 70 healthy volunteers, 13 athletes, and 17 patients with coronary artery disease. Magnetic resonance images were acquired at end diastole and end systole through the ascending aorta, the aortic arch, and the descending thoracic aorta. Regional compliance was derived from the change in luminal area in a slice of known thickness and from the pulse

R H Mohiaddin; S R Underwood; H G Bogren; D N Firmin; R H Klipstein; R S Rees; D B Longmore

1989-01-01

247

Imaging quality analysis of multi-channel scanning radiometer  

NASA Astrophysics Data System (ADS)

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.

Fan, Hong; Xu, Wujun; Wang, Chengliang

2008-03-01

248

Image reconstruction for quality assessment of edge detectors  

Microsoft Academic Search

Extraction of the edges is a key step in image processing and there is still a continuing research effort to develop new and effective edge detection algorithms. Despite this fact, there is no single, reliable and efficient metric to evaluate the quality of an edge detector. We introduce an original method for image reconstruction that leads to edge evaluation based

Barghavi Govindarajan; Karen A. Panetta; Sos Agaian

2008-01-01

249

Comparison of SNR image quality metrics for remote sensing systems  

NASA Astrophysics Data System (ADS)

Different definitions of the signal-to-noise ratio (SNR) are being used as metrics to describe the image quality of remote sensing systems. It is usually not clear which SNR definition is being used and what the image quality of the system is when an SNR value is quoted. This paper looks at several SNR metrics used in the remote sensing community. Image simulations of the Kodak Space Remote Sensing Camera, Model 1000, were produced at different signal levels to give insight into the image quality that corresponds with the different SNR metric values. The change in image quality of each simulation at different signal levels is also quantified using the National Imagery Interpretability Rating Scale (NIIRS) and related to the SNR metrics to better understand the relationship between the metric and image interpretability. An analysis shows that the loss in image interpretability, measured as (Delta) NIIRS, can be modeled as a linear relationship with the noise-equivalent change in reflection (NE(Delta) p). This relationship is used to predict the values that the various SNR metrics must exceed to prevent a loss in the interpretability of the image from the noise.

Fiete, Robert D.; Tantalo, Theodore A.

2001-04-01

250

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

PubMed Central

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.

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

2007-01-01

251

Understanding image quality losses due to smear in high-resolution remote sensing imaging systems  

NASA Astrophysics Data System (ADS)

Space-based high-resolution scanning array imaging systems have the potential to introduce large amounts of image smear. When designing these systems, it is useful to understand how smear will degrade image quality. A brief description of the causes of smear and a simple mathematical model are presented. A series of image simulations (for a system in which (lambda) FN/p equals 1.0, where (lambda) is the mean wavelength for a panchromatic system, FN is the system f number, and p is the pixel pitch of the detectors) are performed in which along scan smear (ranging from 1.0 to 8.0 pixels) is introduced. Using the National Imagery Interpretability Rating Scale (NIIRS), expert observers rated (Delta) NIIRS difference in image quality between the images with simulated smear and the original `unsmeared' image. The functional relationship between smear error and image quality (in units of (Delta) NIIRS) is determined.

Smith, Steven L.; Mooney, James A.; Tantalo, Theodore A.; Fiete, Robert D.

1999-05-01

252

EEG Quality:The Image Acquisition Artefact  

Microsoft Academic Search

\\u000a In this chapter, we focus on the artefacts that arise in the EEG during the fMRI acquisition process. Functional MRI using\\u000a echo planar imaging (EPI) sequences involves the application of rapidly varying magnetic field gradients for spatial encoding\\u000a of the MR signal and radiofrequency (RF) pulses for spin excitation (see the chapter “The Basics of Functional Magnetic Resonance\\u000a Imaging”). Early

Petra Ritter; Robert Becker; Frank Freyer; Arno Villringer

253

Carotid Artery Segmentation in Ultrasound Images and Measurement of Intima-Media Thickness  

PubMed Central

Background. The segmentation of the common carotid artery (CCA) wall is imperative for the determination of the intima-media thickness (IMT) on B-mode ultrasound (US) images. The IMT is considered an important indicator in the evaluation of the risk for the development of atherosclerosis. In this paper, authors have discussed the relevance of measurements in clinical practices and the challenges that one has to face while approaching the segmentation of carotid artery on ultrasound images. The paper presents an overall review of commonly used methods for the CCA segmentation and IMT measurement along with the different performance metrics that have been proposed and used for performance validation. Summary and future directions are given in the conclusion.

Gamad, R. S.; Bansod, P. P.

2013-01-01

254

Characterization of distensibility, plaque burden, and composition of the atherosclerotic carotid artery using magnetic resonance imaging  

PubMed Central

Purpose: Arterial distensibility is a marker that can measure vessel wall functional and structural changes resulting from atherosclerosis with applications including estimation of mechanical properties of the wall. We sought to assess the feasibility of using magnetic resonance imaging (MRI) to include wall distensibility in the characterization of atherosclerotic carotid arteries and to analyze the relationship between distensibility and morphological and compositional plaque features. Methods: Five healthy volunteers were imaged with a multiple-slice CINE MR sequence twice, within 24 h, to determine the interscan reproducibility of distensibility measurements. Twenty-one subjects with >15% carotid stenosis and the five healthy volunteers were imaged using a multicontrast carotid MRI protocol to characterize arterial wall morphology and composition. Normalized wall index (wall area/total vessel area), maximum wall thickness and, if present, percentages of wall area occupied by calcification and lipid-rich necrotic core were determined. A multiple-slice CINE MR sequence was added to the multicontrast protocol to measure the distensibility coefficient (DC) at several locations spanning the bifurcation. The intraclass correlation coefficient (ICC) and the coefficient of variation were used to assess the reproducibility of DC measurements made on the healthy subjects. The DC was compared between arterial segments and between the healthy and diseased groups. Furthermore, within the diseased group, DC was correlated to plaque morphology and composition at each location as well as that averaged over the plaque. Results: Distensibility measurements were highly reproducible: ICC (95% confidence interval) was 0.998 (0.96–1.0) for the common carotid segment and 0.990 (0.92–1.0) for the internal carotid segment. In healthy volunteers, we found significantly higher distensibility in the common segment of the carotid artery compared to the internal carotid segment (mean ± SD = 4.56 ± 1.02 versus 3.56 ± 1.32 × 10?5/Pa; p < 0.05). However, no segmental differences were seen in the diseased group (3.25 ± 1.84 versus 3.26 ± 1.60 × 10?5/Pa; p = 0.607). Location-to-location changes in DC were not found to correlate to changes in the local plaque morphology or composition nor were average DC found to be associated with aggregate plaque features. Conclusions: These results demonstrate the feasibility of MRI to measure distensibility in the carotid artery and to presumably detect changes in distensibility due to age and/or disease. The results suggest that the effect of atherosclerosis on local distensibility may not strongly depend upon the specific underlying plaque features in mild to moderate stenotic carotid lesions though more diffuse or nonlocal changes in arterial distensibility could not be ruled out.

Canton, Gador; Hippe, Daniel S.; Sun, Jie; Underhill, Hunter R.; Kerwin, William S.; Tang, Dalin; Yuan, Chun

2012-01-01

255

Fuzzy control in image qualities of holographic optical elements (HOE)  

NASA Astrophysics Data System (ADS)

A fuzzy control model in image formation qualities of holograms manufactured in dichromated gelatin; Agfa 8E75 and other holographic recording material are described. A new model based on the fuzzy set theory is presented to control spectral shifting from the frequency of construction laser beam to the frequency of request. We are concerned with new simplified procedures inserted in ordinary hologram manufacturing process. From the modulation mechanism in these holograms we seize the intrinsic qualities and our model of fuzzy set analysis show to produce good general agreement with the experimentally measured image formation qualities.

Chang, Rong-Seng; Lin, Chern-Sheng

1994-05-01

256

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

NASA Astrophysics Data System (ADS)

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

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

2008-01-01

257

Multifractal analysis of Arterial Spin Labeling functional Magnetic Resonance Imaging of the brain  

Microsoft Academic Search

This work proposes a multifractal analysis of the time series derived from ASL fMRI (Arterial Spin Labeling functional Magnetic Resonance Imaging) to detect brain activated regions in response to an unknown stimulus. In contrast to standard model-based activation analysis, no prior knowledge of the expected haemodynamic response has to be assumed for extracting activation patterns from fMRI. The ASL time

Filipe Soares; Inês Sousa; Filipe Janela; João Seabra; Manuela Pereira; Mário M. Freire

2010-01-01

258

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

PubMed

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

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

2011-12-01

259

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

260

Quantitative image quality evaluation of MR images using perceptual difference models  

PubMed Central

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

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

2008-01-01

261

ISO 20462: a psychophysical image quality measurement standard  

NASA Astrophysics Data System (ADS)

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.

Keelan, Brian W.; Urabe, Hitoshi

2003-12-01

262

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

NASA Astrophysics Data System (ADS)

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 already measured the elasticity distributions for lipids and fibrous tissues (mixtures of smooth-muscle and collagen fiber) [H. Kanai et al.: Circulation 107 (2003) 3018]. In this study, elasticity distributions were measured for blood clots and calcified tissues. We discuss whether these elasticity distributions, which were measuerd in vitro, can be used as reference data for classifying cross-sectional elasticity images measured in vivo into respective tissues. In addition to the measurement of elasticity distributions, correlations between collagen content and elasticity were investigated with respect to fibrous tissue to estimate the collagen and smooth-muscle content based on elasticity. Collagen and smooth-muscle content may be important factors in determining the stability of the fibrous cap of atherosclerotic plaque. Therefore, correlations between elasticity and elements of the tissue in the arterial wall may provide useful information for the noninvasive diagnosis of plaque vulnerability.

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

2005-06-01

263

Image gathering and restoration - Information and visual quality  

NASA Technical Reports Server (NTRS)

A method is investigated for optimizing the end-to-end performance of image gathering and restoration for visual quality. To achieve this objective, one must inevitably confront the problems that the visual quality of restored images depends on perceptual rather than mathematical considerations and that these considerations vary with the target, the application, and the observer. The method adopted in this paper is to optimize image gathering informationally and to restore images interactively to obtain the visually preferred trade-off among fidelity resolution, sharpness, and clarity. The results demonstrate that this method leads to significant improvements in the visual quality obtained by the traditional digital processing methods. These traditional methods allow a significant loss of visual quality to occur because they treat the design of the image-gathering system and the formulation of the image-restoration algorithm as two separate tasks and fail to account for the transformations between the continuous and the discrete representations in image gathering and reconstruction.

Mccormick, Judith A.; Alter-Gartenberg, Rachel; Huck, Friedrich O.

1989-01-01

264

3D volume-selective turbo spin echo for carotid artery wall imaging with navigator detection of swallowing  

Microsoft Academic Search

Purpose: To improve 3D volume-selective turbo spin echo (TSE) carotid artery wall imaging by incorporating naviga- tors to reduce artifacts caused by swallowing. Materials and Methods: Images were acquired on a Sie- mens Magnetom Sonata 1.5T scanner. 3D volume-selective TSE scans of the carotid arteries were acquired in six healthy volunteers. A cross-pair navigator placed on the back of the

Lindsey A. Crowe; Jennifer Keegan; Peter D. Gatehouse; Raad H. Mohiaddin; Anitha Varghese; Karen Symmonds; Timothy M. Cannell; Guang Zhong Yang; David N. Firmin

2005-01-01

265

Quality of life in elderly patients following coronary artery bypass grafting  

PubMed Central

Background Surgical revascularization of the coronary arteries leads to changes in quality of life (QoL) for patients with coronary heart disease. The aim of this work was to monitor QoL, considering cognitive function, depression, and activities of daily living in elderly patients after coronary artery bypass grafting (CABG). Methods This study included 65 patients (29 women and 36 men) aged 61–74 years with stable coronary heart disease who underwent CABG. The control group included 29 women and 36 men aged 61–74 years who were not suffering from coronary heart disease. The questionnaires used in the study canvassed QoL (Nottingham Health Profile), cognitive function, depression, and basic and instrumental activities of daily living. The research was conducted before surgery and repeated 6 and 12 months after surgery. Results QoL was comparable between women and men and was lower than in the control group (P<0.05). After CABG, the values for particular domains of QoL improved more in men than in women. There was a reduction in the severity of depression 6 months after surgery in men and 12 months after surgery in women. Conclusion Elderly patients with coronary heart disease have decreased QoL, which normalizes in men and improves in women after CABG.

Bak, Ewelina; Marcisz, Czeslaw

2014-01-01

266

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

NASA Astrophysics Data System (ADS)

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

Corchs, Silvia; Gasparini, Francesca; Schettini, Raimondo

2014-01-01

267

Evidence quality imaging for bank security  

Microsoft Academic Search

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

P. Gallagher; S. Doyle

1995-01-01

268

Coolant quality for magnetic resonance imaging systems  

Microsoft Academic Search

As radiologists demand increased power, speed and duty cycle from their magnetic resonance imaging (MRI) systems, thermal management of the gradient sub-system becomes more challenging. A heat exchanger in the MRI system cools heat-generating components by pumping water through hollow copper tubing, which also carries high electrical currents. Water is used as a coolant because of its high specific heat

Julie Wong; Garron K Morris

2008-01-01

269

Quality Evaluation of Digital Image Watermarking  

Microsoft Academic Search

In the last few years, digital image watermarking have been proposed as a solution for solving the illegal copying and proof of ownership problem in the context of multimedia object. But it is still difficult have a rough standard of their performances and hence to compare them. So we propose a suggestion standard based on the hiding property and robustness

Qingtang Su; Xianxi Liu; Steve Zhang

2009-01-01

270

The influence of software filtering in digital mammography image quality  

NASA Astrophysics Data System (ADS)

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.

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

2009-05-01

271

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

SciTech Connect

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.

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

272

Cross-Sectional Elastic Imaging of Arterial Wall Using Intravascular Ultrasonography  

NASA Astrophysics Data System (ADS)

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, the smooth muscle has an almost purely elastic characteristic. However, the IVUS probe moves greatly due to the arrival of the pulsatile wave at the beginning of the ejection period. Therefore, in this paper, we propose a method to compensate for the movement of the IVUS probe in order to precisely measure the regional change in thickness of the arterial wall during one cardiac cycle. Basic experiments using a silicone rubber tube, in which pulsatile flow is generated by an artificial heart, determined the two-dimensional (2-D) distribution of the regional change in thickness and the elasticity. The obtained incremental elastic modulus coincides with that determined by the static pressure-strain test. Furthermore, in an in vitro experiment performed on an extracted human iliac artery, the 2-D distribution of elasticity is obtained and compared with pathological results.

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

2001-07-01

273

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

PubMed

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

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

2012-01-01

274

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

PubMed Central

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

New, Sophie E. P.; Aikawa, Elena

2011-01-01

275

High bandwidth FASTBUS based data acquisition system for imaging coronary arteries  

SciTech Connect

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.

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

1983-10-01

276

Image Quality Improvement after Implementation of a CT Accreditation Program  

PubMed Central

Objective The purpose of this study was to evaluate any improvement in the quality of abdominal CTs after the utilization of the nationally based accreditation program. Materials and Methods Approval was obtained from the Institutional Review Board, and informed consent was waived. We retrospectively analyzed 1,011 outside abdominal CTs, from 2003 to 2007. We evaluated images using a fill-up sheet form of the national accreditation program, and subjectively by grading for the overall CT image quality. CT scans were divided into two categories according to time periods; before and after the implementation of the accreditation program. We compared CT scans between two periods according to parameters pertaining to the evaluation of images. We determined whether there was a correlation between the results of a subjective assessment of the image quality and the evaluation scores of the clinical image. Results The following parameters were significantly different after the implementation of the accreditation program: identifying data, display parameters, scan length, spatial and contrast resolution, window width and level, optimal contrast enhancement, slice thickness, and total score. The remaining parameters were not significantly different between scans obtained from the two different periods: scan parameters, film quality, and artifacts. Conclusion After performing the CT accreditation program, the quality of the outside abdominal CTs show marked improvement, especially for the parameters related to the scanning protocol.

Kim, You Sung; Choi, Byung Gil; Shin, Yu Ri; Hwang, Seong Su; Ku, Young Mi; Lim, Yeon Soo; Lee, Jae Mun

2010-01-01

277

Slider-adjusted softcopy ruler for calibrated image quality assessment  

NASA Astrophysics Data System (ADS)

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.

Jin, Elaine W.; Keelan, Brian W.

2010-01-01

278

Influence of acquisition parameters on MV-CBCT image quality.  

PubMed

The production of high quality pretreatment images plays an increasing role in image-guided radiotherapy (IGRT) and adaptive radiation therapy (ART). Megavoltage cone-beam computed tomography (MV-CBCT) is the simplest solution of all the commercially available volumetric imaging systems for localization. It also suffers the most from relatively poor contrast due to the energy range of the imaging photons. Several avenues can be investigated to improve MV-CBCT image quality while maintaining an acceptable patient exposure: beam generation, detector technology, reconstruction parameters, and acquisition parameters. This article presents a study of the effects of the acquisition scan length and number of projections of a Siemens Artiste MV-CBCT system on image quality within the range provided by the manufacturer. It also discusses other aspects not related to image quality one should consider when selecting an acquisition protocol. Noise and uniformity were measured on the image of a cylindrical water phantom. Spatial resolution was measured using the same phantom half filled with water to provide a sharp water/air interface to derive the modulation transfer function (MTF). Contrast-to-noise ratio (CNR) was measured on a pelvis-shaped phantom with four inserts of different electron densities relative to water (1.043, 1.117, 1.513, and 0.459). Uniformity was independent of acquisition protocol. Noise decreased from 1.96% to 1.64% when the total number of projections was increased from 100 to 600 for a total exposure of 13.5 MU. The CNR showed a ± 5% dependence on the number of projections and 10% dependence on the scan length. However, these variations were not statistically significant. The spatial resolution was unaffected by the arc length or the sampling rate. Acquisition parameters have little to no effect on the image quality of the MV-CBCT system within the range of parameters available on the system. Considerations other than image quality, such as memory storage, acquisition speed, and individual projection image quality, speak in favor of the use of a coarse sampling rate on the short scan. PMID:22231215

Gayou, Olivier

2012-01-01

279

Thematic mapper image quality - Preliminary results  

NASA Technical Reports Server (NTRS)

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.

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

1983-01-01

280

Thematic Mapper image quality: Preliminary results  

NASA Technical Reports Server (NTRS)

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.

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

1983-01-01

281

Mirror image distal anterior cerebral artery aneurysms treated with coil embolization. a report of two cases and literature review.  

PubMed

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

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

2013-03-01

282

Optimizing radiation dose and image quality  

Microsoft Academic Search

Radiation exposure is a critical issue in multidetector CT (MDCT) particularly since fast MDCT scanners have become widely\\u000a available, and the method has been proposed as a noninvasive diagnostic tool for an increasing number of clinical applications.\\u000a Additional features of MDCT imaging affecting individual dose are related to the inappropriate use of scanners caused by practices\\u000a such as scanning beyond

Carlo Catalano; Marco Francone; Adriano Ascarelli; Matteo Mangia; Ilaria Iacucci; Roberto Passariello

2007-01-01

283

NIIRS and Objective Image Quality Measures  

Microsoft Academic Search

The introduction of image distortion during compression is of widespread concern, to the extent that the nature and size of\\u000a the distortion may influence the choice of codec. The ability to quantify the distortion for particular applications is therefore\\u000a highly desirable, particularly when options for new compression standards (such as JPEG 2000) are being considered. We report\\u000a on the performance

K. J. Hermiston; David M. Booth

1999-01-01

284

Perceptual assessment of image quality in multimedia technology  

NASA Astrophysics Data System (ADS)

Fast development of multimedia technology during the last two decades has brought different approach to the evaluation of image quality. In most of the cases, multimedia technology applications do not rely on the image fidelity criterion but the human impression plays the main role. A model for perceptual assessment of image quality in multimedia technology is presented in this paper. The model exploits properties of the human visual system (HVS) while utilizing steerable pyramidal decomposition. Image distortion features are based on Jeffrey divergence (JD) as a metric between probability distributions of original and distorted image signal values in each subband of steerable pyramid. Mean square error (MSE) is also computed. Data preprocessing using mutual information (MI) approach has been used to get a smaller set of objective distortion features describing the perceived image quality with reasonable precision. The impairment feature vector is processed by the radial basis function (RBF) artificial neural network (ANN) to allow simple adaptation of the model in respect to the required mode of operation, fidelity or impressiveness based. Parameters of the ANN are adjusted using mean opinion scores (MOS) obtained from the group of assessors. The presented system mimics an assessment process with human subjects. Model performance is verified comparing predicted quality and scores from human observers.

Fliegel, Karel

2007-10-01

285

Evaluation of image quality in computed radiography based mammography systems  

NASA Astrophysics Data System (ADS)

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.

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

2011-03-01

286

APQ-102 imaging radar digital image quality study  

NASA Astrophysics Data System (ADS)

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

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

1982-11-01

287

Quantification of carotid arteries atherosclerosis using 3D ultrasound images and area-preserving flattened maps  

NASA Astrophysics Data System (ADS)

Quantitative measurements of the progression (or regression) of carotid plaque burden are important in monitoring patients and evaluating new treatment options. 3D ultrasound (US) has been used to monitor the progression of carotid artery plaques in symptomatic and asymptomatic patients. Different methods of measuring various ultrasound phenotypes of atherosclerosis have been developed. In this work, we extended concepts used in intima-media thickness (IMT) measurements based on 2D images and introduced a metric called 3D vessel-wall-plus-plaque thickness (3D VWT), which was obtained by computing the distance between the carotid wall and lumen surfaces on a point-by-point basis in a 3D image of the carotid arteries. The VWT measurements were then superimposed on the arterial wall to produce the VWT map. Since the progression of plaque thickness is important in monitoring patients who are at risk for stroke, we also computed the change of VWT by comparing the VWT maps obtained for a patient at two different time points. In order to facilitate the visualization and interpretation of the 3D VWT and VWT-Change maps, we proposed a technique to flatten these maps in an area-preserving manner.

Chiu, Bernard; Egger, Micaela; Spence, J. David; Parraga, Grace; Fenster, Aaron

2008-04-01

288

Understanding image quality losses due to smear in high-resolution remote sensing imaging systems  

Microsoft Academic Search

Space-based high-resolution scanning array imaging systems have the potential to introduce large amounts of image smear. When designing these systems, it is useful to understand how smear will degrade image quality. A brief description of the causes of smear and a simple mathematical model are presented. A series of image simulations (for a system in which (lambda) FN\\/p equals 1.0,

Steven L. Smith; James A. Mooney; Theodore A. Tantalo; Robert D. Fiete

1999-01-01

289

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

SciTech Connect

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.

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

1985-07-01

290

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

NASA Astrophysics Data System (ADS)

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

Rogowitz, Bernice E.; Rushmeier, Holly E.

2001-06-01

291

Hepatocellular carcinoma associated with budd-chiari syndrome: imaging features and transcatheter arterial chemoembolization  

PubMed Central

Background Budd–Chiari syndrome (BCS) often leads to hepatocellular carcinoma (HCC). Transcatheter arterial chemoembolization (TACE) has been increasingly used to treat BCS patients with HCC. The purposes of this study were to illustrate imaging features in BCS patients with HCC, and to analyze the effects of TACE on BCS patients with HCC. Methods 246 consecutive patients with primary BCS were retrospectively studied. 14 BCS patients with HCC were included in this study. BCS were treated with angioplasty and/or stenting, and HCC were managed with TACE. Imaging features on ultrasonography, CT, MRI, and angiography and the serum AFP level were analyzed. Results Inferior vena cava block and stricture of hepatic venous outflow tract more frequently occurred. Portal vein invasion was found in only 2 patients (14.2%). Imaging studies showed that most nodules of HCC were near the edge of liver, irregular, more than 3 cm in diameter, heterogeneous mass and solitary (?3 nodules). HCC in patients associated with BCS was isointense or hypointense in nonenhanced CT images, and exhibited heterogeneous enhancement during the arterial phase and washout during the portal venous phase on enhanced CT and MRI. The serum AFP level significantly declined after TACE treatment. Conclusions BCS patients with inferior vena cava block and stricture of hepatic venous outflow tract seems to be associated with HCC. A single, large, irregular nodule with a peripheral location appears to be HCC. TACE can effectively treat HCC in BCS patients.

2013-01-01

292

High quality, low complexity image scaler suitable for rational factors  

Microsoft Academic Search

2D image resizing is an important issue for pixel oriented displays with variable input formats. With current separable filters including high order polyphase filters, the problem of jagged lines at diagonal edges remains. Another issue is the need of simple but high-quality sealers for a wide range of applications. The novel approach investigated for high-quality resizing by rational factors is

C. Hentschel; S. Schiemenz

2006-01-01

293

The Relationships Between Regional Arterial Inflammation, Calcification, Risk Factors and Biomarkers - A Prospective FDG PET/CT Imaging Study  

PubMed Central

Background Fluorodeoxyglucose positron emission tomography (FDG PET) imaging of atherosclerosis has been used to quantify plaque inflammation and to measure the effect of plaque stabilizing drugs. Here we explore how atherosclerotic plaque inflammation varies across arterial territories and how it relates to arterial calcification. We also test the hypotheses that the degree of local arterial inflammation measured by PET is correlated with the extent of systemic inflammation and presence of risk factors for vascular disease. Methods and Results Forty-one subjects underwent vascular PET/CT imaging with FDG. All had either vascular disease or multiple risk factors for it. Forty subjects underwent carotid imaging, twenty-seven underwent aortic, twenty-four iliac and thirteen femoral imaging. Thirty-three subjects had a panel of biomarkers analyzed. We found strong associations between FDG uptake in neighboring arteries (left vs. right carotid r=0.91, p<0.001, ascending aorta vs. aortic arch r=0.88, p<0.001). Calcification and inflammation rarely overlapped within arteries – carotid artery FDG uptake vs. calcium score r=?0.42, p=0.03). Carotid artery FDG uptake was greater in those with a history of coronary artery disease (target to background ratio (TBR) 1.83 vs. 1.61, p<0.01), and in males vs. females (TBR 1.83 vs. 1.63, p<0.05). Similar findings were also noted in the aorta and iliac arteries. Subjects with the highest levels of FDG uptake also had the greatest concentrations of inflammatory biomarkers: descending aorta TBR vs. matrix metalloproteinase 3 (MMP 3): r=0.53, p=0.01 and carotid TBR vs. MMP 9: r=0.50, p=0.01. Non-significant positive trends were seen between FDG uptake and levels of interleukin 18, fibrinogen and C-reactive protein. Finally, we found that the atheroprotective biomarker adiponectin was negatively correlated with the degree of arterial inflammation in the descending aorta: r=?0.49, p=0.03). Conclusions This study shows that FDG PET imaging can increase our knowledge of how atherosclerotic plaque inflammation relates to calcification, serum biomarkers and vascular risk factors. Plaque inflammation and calcification rarely overlap, supporting the theory that calcification represents a late, burnt-out stage of atherosclerosis. Inflammation in one arterial territory is associated with inflammation elsewhere, and the degree of local arterial inflammation is reflected in the blood levels of several circulating biomarkers. We suggest that FDG PET imaging could be used as a surrogate marker of both atherosclerotic disease activity and drug effectiveness. Prospective, event driven studies are now underway to determine the role of this technique in clinical risk prediction.

Rudd, James HF; Myers, Kelly S; Bansilal, Sameer; Machac, Josef; Woodward, Mark; Fuster, Valentin; Farkouh, Michael E; Fayad, Zahi A

2011-01-01

294

Image quality evaluation with a contour-based perceptual model  

NASA Astrophysics Data System (ADS)

A computational model for the human perception of image brightness utilizing both local and global interactions has been advanced by Grossberg, Mingolla and Todorovic. A simulation of this multi-layer, non-linear recurrent network model can be used to assess perceived image quality. The model is validated by examining the simulation of a classical brightness perception phenomenon, in particular, Glass patterns. Results of a comparative evaluation of three halftoning algorithms are offered which indicate that the model is useful for the evaluation of image processing algorithms. Human subjects ranked the quality of the images halftoned with each of three different algorithms at two different viewing distances. After processing by the brightness perception model, ranking of objective measures of the simulated model output correspond with the rankings assigned by human observers.

Grogan, Timothy A.; Keene, David P.

1992-08-01

295

Investigating Mechanisms of Image Quality Enhancement Associated with Tissue Harmonic Imaging  

NASA Astrophysics Data System (ADS)

Enhancements to the compactness of the nonlinearly generated second harmonic (2f) field component (narrower main-lobe and reduced side-lobe levels) and reduced impact of phase and amplitude aberration, with respect to the fundamental (1f) field component, are among the proposed factors contributing to the observed image quality improvements with harmonic imaging in diagnostic ultrasound. Despite the wide clinical use of harmonic imaging, however, the details of the mechanisms responsible for the associated image quality improvements are still not fully understood. The concept of an ``effective apodization'' is defined as a potentially useful tool for providing a linear approximation to the nonlinearly generated field components.

Wallace, Kirk D.; Holland, Mark R.; Miller, James G.

2006-05-01

296

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

PubMed

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

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

2014-01-01

297

A perceptually relevant MSE-based image quality metric.  

PubMed

Image quality metrics (IQMs), such as the mean squared error (MSE) and the structural similarity index (SSIM), are quantitative measures to approximate perceived visual quality. In this paper, through analyzing the relationship between the MSE and the SSIM under an additive noise distortion model, we propose a perceptually relevant MSE-based IQM, MSE-SSIM, which is expressed in terms of the variance of the source image and the MSE between the source and distorted images. Evaluations on three publicly available databases (LIVE, CSIQ, and TID2008) show that the proposed metric, despite requiring less computation, compares favourably in performance to several existing IQMs. In addition, due to its simplicity, MSE-SSIM is amenable for the use in a wide range of image and video tasks that involve solving an optimization problem. As an example, MSE-SSIM is used as the objective function in designing a Wiener filter that aims at optimizing the perceptual visual quality of the output. Experimental results show that the images filtered with a MSE-SSIM-optimal Wiener filter have better visual quality than those filtered with a MSE-optimal Wiener filter. PMID:24057005

Tan, Hui Li; Li, Zhengguo; Tan, Yih Han; Rahardja, Susanto; Yeo, Chuohuo

2013-11-01

298

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

NASA Astrophysics Data System (ADS)

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

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

2000-04-01

299

Objective quality evaluation of visible and infrared color fusion image  

NASA Astrophysics Data System (ADS)

An evaluation for objectively assessing the quality of visible and infrared color fusion image is proposed. On the basis of the consideration that human perception is most sensitive to color, sharpness, and contrast when assessing the quality of color image, we propose four objective metrics: image sharpness metric (ISM), image contrast metric (ICM), color colorfulness metric (CCM), and color naturalness metric (CNM). The ISM is evaluated by image gradient information. The ICM is defined based on both gray and color histogram characteristics. A color chroma metric, as well as a color variety metric based on a color difference gradient, is proposed, respectively, to define the CCM. The CNM is defined by measuring the color distribution's similarity between the fusion image and nature image, which are of the same scene. All the color attributions are computed in the CIELAB color space. Experimental results show that the proposed objective metrics are meaningful and effective on color fusion image evaluation because they correspond well to subjective evaluation.

Yuan, Yihui; Zhang, Junju; Chang, Benkang; Han, Yiyong

2011-03-01

300

No-reference image quality assessment for horizontal-path imaging scenarios  

NASA Astrophysics Data System (ADS)

There exist several image-enhancement algorithms and tasks associated with imaging through turbulence that depend on defining the quality of an image. Examples include: "lucky imaging", choosing the width of the inverse filter for image reconstruction, or stopping iterative deconvolution. We collected a number of image quality metrics found in the literature. Particularly interesting are the blind, "no-reference" metrics. We discuss ways of evaluating the usefulness of these metrics, even when a fully objective comparison is impossible because of the lack of a reference image. Metrics are tested on simulated and real data. Field data comes from experiments performed by the NATO SET 165 research group over a 7 km distance in Dayton, Ohio.

Rios, Carlos; Gladysz, Szymon

2013-05-01

301

High-Resolution 3 T MR Microscopy Imaging of Arterial Walls  

SciTech Connect

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.

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

302

Body image quality of life in eating disorders  

PubMed Central

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

Jauregui Lobera, Ignacio; Bolanos Rios, Patricia

2011-01-01

303

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

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

304

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

PubMed Central

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

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

2013-01-01

305

Flattening filter removal for improved image quality of megavoltage fluoroscopy  

SciTech Connect

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.

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

306

Usefulness of real-time navigator magnetic resonance imaging for evaluating coronary artery origins in pediatric patients.  

PubMed

Navigator coronary magnetic resonance imaging (MRI) was evaluated in assessing coronary artery origins in a pediatric and adolescent population. Sixty-five consecutive infants, children, or adolescents (age range 11 days to 21 years) were referred for MRI evaluations to assess coronary artery origins. Coronary artery origins were unambiguously delineated in 62 of 65 patients. In 3 patients, irregular arrhythmias precluded cardiac gating of the magnetic resonance acquisition. Two patients had anomalous coronary artery origins detected. Twenty-six patients required sedation for the studies. Free-breathing 3-dimensional MRI with real-time navigator correction is a robust method for delineating the coronary artery origins in pediatric and adolescent patients. PMID:15721121

Su, Jason T; Chung, Taylor; Muthupillai, Raja; Pignatelli, Ricardo H; Kung, Grace C; Diaz, Laura K; Vick, G Wesley; Kovalchin, John P

2005-03-01

307

Thematic Mapper image quality - Registration, noise, and resolution  

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

308

High-speed terahertz imaging toward food quality inspection.  

PubMed

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

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

2014-03-01

309

Label-free imaging of arterial tissues using photonic crystal fiber (PCF) based nonlinear optical microscopic system  

NASA Astrophysics Data System (ADS)

Nonlinear optical (NLO) microscopy provides a minimally invasive optical method for fast molecular imaging at subcellular resolution with 3D sectioning capability in thick, highly scattering biological tissues. In the current study, we demonstrate the imaging of arterial tissue using a nonlinear optical microscope based on photonic crystal fiber and a single femto-second oscillator operating at 800nm. This NLO microscope system is capable of simultaneous imaging extracellular elastin/collagen structures and lipid distribution within aortic tissue obtained from coronary atherosclerosis-prone WHHLMI rabbits (Watanabe heritable hyperlipidemic rabbit-myocardial infarction) Clear pathological differences in arterial lumen surface were observed between healthy arterial tissue and atherosclerotic lesions through NLO imaging.

Ko, Alex C. T.; Ridsdale, Andrew; Pegoraro, Adrian F.; Smith, Michael S. D.; Mostaço-Guidolin, Leila B.; Hewko, Mark D.; Kohlenberg, Elicia M.; Schattka, Bernie J.; Shiomi, Masashi; Stolow, Albert; Sowa, Michael G.

2009-02-01

310

New Pathways Towards the Enhancement of the Image Quality  

Microsoft Academic Search

In this paper, experimental results and data analysis on a novel technique aimed at increasing the image quality of the target, surrounded by a scattering medium, is presented. Specifically, enhanced target detection has been obtained by doping the surrounding medium with molecular contrast agents, consisting polar molecules yielding to an enhanced contract and specificity of the target, utilizing advanced polarimetric

G. C. Giakos; S. Atreya Paturi; P. Bathini; S. Sukumar; K. Ambadipudi; K. Valiuru; D. Wagenar; V. Adya; M. Reddy

2007-01-01

311

Subjective and objective quality assessment in wireless teleultrasonography imaging  

Microsoft Academic Search

Mobile Robotic teleultrasonography is an emerging technology that can be applied in different clinical settings for remote ultrasound scanning without the need of the expert at the point of care. Guaranteed medical image quality for diagnostic purposes and their delivery in bandwidth limited wireless environments is a challenging issue. In this paper we present some of the subjective and objective

R. S. H. Istepanian; N. Philip; M. G. Martini; N. Amso; P. Shorvon

2008-01-01

312

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.

313

Retinal Image Quality and Postnatal Visual Experience during Infancy  

PubMed Central

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

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

2009-01-01

314

Image quality, space-qualified UV interference filters  

NASA Technical Reports Server (NTRS)

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

Mooney, Thomas A.

1992-01-01

315

Image quality, space-qualified UV interference filters  

NASA Astrophysics Data System (ADS)

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

Mooney, Thomas A.

1992-09-01

316

Comparison of two common aerial reconnaissance image quality measures  

Microsoft Academic Search

The assessment of imaging system performance is critical to ensuring a system is delivering the highest quality products possible. The principle two methods for evaluation of reconnaissance system performance are resolution and the National Imagery Interpretability Rating Scale (NIIRS). This paper describes both methods, and presents benefits and limitations of each. Use of the NIIRS is shown to be on

Kenneth Riehl; Larry Maver

1996-01-01

317

Optoelectronic complex inner product for evaluating quality of image segmentation  

NASA Astrophysics Data System (ADS)

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.

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

2000-11-01

318

Corrections of arterial input function for dynamic H215O PET to assess perfusion of pelvic tumours: arterial blood sampling versus image extraction  

NASA Astrophysics Data System (ADS)

Assessment of perfusion with 15O-labelled water (H215O) requires measurement of the arterial input function (AIF). The arterial time activity curve (TAC) measured using the peripheral sampling scheme requires corrections for delay and dispersion. In this study, parametrizations with and without arterial spillover correction for fitting of the tissue curve are evaluated. Additionally, a completely noninvasive method for generation of the AIF from a dynamic positron emission tomography (PET) acquisition is applied to assess perfusion of pelvic tumours. This method uses a volume of interest (VOI) to extract the TAC from the femoral artery. The VOI TAC is corrected for spillover using a separate tissue TAC and for recovery by determining the recovery coefficient on a coregistered CT data set. The techniques were applied in five patients with pelvic tumours who underwent a total of 11 examinations. Delay and dispersion correction of the blood TAC without arterial spillover correction yielded in seven examinations solutions inconsistent with physiology. Correction of arterial spillover increased the fitting accuracy and yielded consistent results in all patients. Generation of an AIF from PET image data was investigated as an alternative to arterial blood sampling and was shown to have an intrinsic potential to determine the AIF noninvasively and reproducibly. The AIF extracted from a VOI in a dynamic PET scan was similar in shape to the blood AIF but yielded significantly higher tissue perfusion values (mean of 104.0 ± 52.0%) and lower partition coefficients (-31.6 ± 24.2%). The perfusion values and partition coefficients determined with the VOI technique have to be corrected in order to compare the results with those of studies using a blood AIF.

Lüdemann, L.; Sreenivasa, G.; Michel, R.; Rosner, C.; Plotkin, M.; Felix, R.; Wust, P.; Amthauer, H.

2006-06-01

319

Extrahepatic visualization in the distribution of falciform artery in posttreatment Bremsstrahlung images after radioembolization with (90)Y microspheres.  

PubMed

We report the case of a 39-year-old female with metastatic colorectal cancer. Pretreatment SPECT/CT imaging revealed extrahepatic tracer accumulation along the falciform artery distribution. Prior to the administration of (90)Y microspheres, hepatic arterial anatomy was evaluated angiographically. It was not possible to identify the hepatic falciform artery so that no coil-embolization was performed. The patient tolerated the treatment well with only mild pain around the umbilicus during the procedure that spontaneously abated. As far as we know, this is the first report of Bremsstrahlung SPECT/CT images that has clearly shown that the microspheres accumulation in the anterior abdominal wall corresponds to hepatic falciform artery distribution on CT. PMID:24438915

Beylergil, V; Sofocleous, C T; Carrasquillo, J A

2014-01-01

320

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

SciTech Connect

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

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

1987-01-01

321

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

PubMed

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

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

2014-03-01

322

Circuitry analyses by using high quality image acquisition and multi-layer image merge technique  

Microsoft Academic Search

By using high quality image acquisition and multi-layer image merge technique, a technique of IC circuitry analysis has been developed and successfully applied to more than 50 industrial products analysis in one year. A series of in-house designed software ensures the successful rate to be up to 95% and the total working time to be less than 2 months for

H. P. Yao; Qi Zhong; Vic Ku; C. K. Lo; Y. R. Wu; Y. F. Hsieh

2005-01-01

323

Dependence of Image Quality on Image Operator and Noise for Optical Diffusion Tomography  

Microsoft Academic Search

By applying linear perturbation theory to the radiation transport equation, the inverse problem of optical diffusion tomography can be reduced to a set of linear equations, Wm5R, where W is the weight function, m are the cross-section perturbations to be imaged, and R is the detector readings perturbations. We have studied the dependence of image quality on added systematic error

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

1998-01-01

324

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

Microsoft Academic Search

Functional magnetic resonance imaging (fMRI) at high magnetic field strength can suffer from serious degradation of image quality because of motion and physiological noise, as well as spatial distortions and signal losses due to susceptibility effects. Overcoming such limitations is essential for sensitive detection and reliable interpretation of fMRI data. These issues are particularly problematic in studies of awake animals.

Gang Chen; Feng Wang; Barbara C. Dillenburger; Robert M. Friedman; Li M. Chen; John C. Gore; Malcolm J. Avison; Anna W. Roe

325

A mechanism for the management and optimization of imaging systems with non-uniform imaging quality  

Microsoft Academic Search

When imaging data is collected using airborne remote sensing systems, it is common that the image quality (IQ) of the collected data is not uniform over the entire region of collection. This non-uniformity of IQ is often a limiting factor to the utility of collected data. It would therefore be useful to have a mechanism to predict, assess and manage

Thomas A. Sanderson; Paul Sprague; Steven L. Smith; Rulon E. Simmons; Raymond T. Lines

2005-01-01

326

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

SciTech Connect

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.

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

1982-12-01

327

Image denoising and quality assessment through the Renyi entropy  

NASA Astrophysics Data System (ADS)

This paper presents a new image denoising method based on truncating the original noisy coefficients of a Pseudo- Wigner distribution (PWD) calculated through 1D directional windows. This method has been tested both for additive and multiplicative noisy images. The coefficients are selected according to their local directionality to take into account the image anisotropy. Next, the PWD is inverted and the set of different directional images are averaged. When the ground truth image reference is available, the peak signal-to-noise ratio (PSNR) metric is used to evaluate the resulting denoised images in comparison with other alternative methods. The described method is based on the use of the Renyi entropy extracted from a joint spatial frequency representation such as the Wigner distribution. A comparison with other competitive techniques is described and tested for real-world images. In particular, some experimental results are presented in the area of synthetic aperture radar (SAR) and retinal imaging, showing the effectiveness of the method in comparison with other alternative techniques through the use of two different non-reference image quality metrics.

Gabarda, Salvador; Redondo, Raphael; Gil, Elena; Cristóbal, Gabriel

2009-08-01

328

Diagnostic quality of low resolution images for tele-woundcare.  

PubMed Central

The use of digital wound images would allow remote consultation between patients, physicians, or other caregivers over the Internet. To evaluate the efficacy and validity of digital images for assessment of wounds, we compared the ability and reliability of surgeons to diagnose and make treatment suggestions using either digital or slide images of several types of wounds. Twenty-four wound images on 35-mm slides were selected for use in this study. Each slide image was digitized at 24-bit color with a resolution of 640 pixels horizontal by 425 pixels vertical, and stored as a JPEG file. Six physicians, of varying experience, examined the images, first in digital format and then later in the original slide form. Each observer assessed each wound for condition and possible treatment options by filling out a questionnaire using a series of yes/no questions. For all observers, there was an 87% agreement of answers between digital and slide images (p = 0.004). The agreement between the digital and slide images was also measured for each individual observer using a kappa coefficient. The agreement kappa correlated with the experience of the observer, with the kappa values ranging from greater than 0.8 (almost perfect agreement) for an experienced woundcare professional to just greater than 0.5 (moderate agreement) for a surgical intern. With this study, we have demonstrated the feasibility of distance wound consultation using digital images of a quality consistent with consumer-grade digital photography.

Roth, A. C.; Reid, J. C.; Concannon, M.

1998-01-01

329

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

Microsoft Academic Search

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

Yucheng Wang; Dewen Hu; Yadong Liu; Ming Li

2011-01-01

330

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

PubMed Central

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.

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

2014-01-01

331

Non-invasive imaging of carotid arterial restenosis using 3T cardiovascular magnetic resonance  

PubMed Central

Background Restenosis of the carotid artery is common following carotid endarterectomy, but analysis of lesion composition has mostly been based on histological study of explanted restenotic lesions. This study investigated the ability of 3T cardiovascular magnetic resonance (CMR) to determine the components of recurrent carotid artery disease and examined whether these differed from primary atherosclerotic plaque. Methods 50 patients underwent 3T CMR of both carotid arteries using a standard multicontrast protocol: time-of-flight (TOF), T1-weighted (T1W), T2-weighted (T2W), and PD-weighted (PDW) Turbo-Spin-Echo (TSE) sequences. 25 patients had previously undergone carotid endarterectomy (mean time since surgery 1580 days, range 45–6560 days), and 25 with primary asymptomatic atherosclerotic plaques served as controls. Two experienced reviewers analysed the multicontrast CMR images according to the presence or absence of major plaque features and assigned an overall classification type. Results In patients with recurrent carotid disease following endarterectomy, the mean degree of restenosis was 51% (range 30–90%). Three distinct types of restenosis were identified: 5 patients (20%) showed CMR characteristics of fibro-atheromatous tissue, 11 patients (44%) had plaque features consistent with possible myointimal (fibromuscular) hyperplasia, and 6 patients (24%) had recurrent plaque suggestive of further lipid accumulation. Three patients (12%) showed evidence of post-surgical dissection of the carotid intima. Compared to primary atherosclerotic plaques, restenotic plaques were more likely to contain fibro-atheromatous tissue (p = 0.05) and smooth muscle (p < 0.01), and less likely to contain lipid (p < 0.01). Composition did not differ significantly between patients with early and late restenosis. Conclusions As defined by CMR, restenotic lesions of the carotid artery fall into three distinct types and differ in composition from primary atherosclerotic plaques. If validated by subsequent histological studies, these findings could suggest a role for CMR in detecting high-risk (i.e. lipid-rich) restenotic lesions.

2014-01-01

332

Image quality measurements with a neural brightness perception model  

NASA Astrophysics Data System (ADS)

A computational model for the human perception of image brightness has been advanced by Cohen, Grossberg, and Todorovic. The research describes how this model can be used to assess perceived image quality. The implementation of the model is extended to allow the processing of larger images and an increased dynamic range of the gray scale. The model is validated by examining the simulation of some classical brightness perception phenomena including the Herman grid illusion, and the Craik-O'Brien-Cornsweet effect. Results of a comparative evaluation of three halftoning algorithms are offered which indicate that the model is useful for the evaluation of image processing algorithms. Human subjects ranked the quality of the images halftoned with each of three different algorithms at three different viewing distances. Objective measures of the halftoned images were obtained after preprocessing to account for the different viewing distances. The ranking of the objective measures did not correspond to those of the majority of the human observers. However, after processing by the brightness perception model, ranking of the objective measures do correspond with the rankings assigned by human observers.

Grogan, Timothy A.; Wu, Mei

1991-06-01

333

Blind Image Quality Assessment: From Natural Scene Statistics to Perceptual Quality  

Microsoft Academic Search

Our approach to blind image quality assessment (IQA) is based on the hypothesis that natural scenes possess certain statistical properties which are altered in the presence of distortion, rendering them un-natural; and that by character- izing this un-naturalness using scene statistics, one can identify the distortion afflicting the image and perform no-reference (NR) IQA. Based on this theory, we propose

Anush Krishna Moorthy; Alan Conrad Bovik

2011-01-01

334

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

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

335

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

PubMed Central

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.

2014-01-01

336

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

PubMed

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

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

2013-06-15

337

A SPECT study in internal carotid artery occlusion: Discrepancies between flow image and neurologic deficits  

SciTech Connect

A SPECT (single photon emission computed tomography) study in internal carotid artery (ICA) occlusion was performed in 6 patients. The validity of iodoamphetamine (IMP) SPECT study in the evaluation of cerebral blood flow (CBF) or neurologic function is still controversial. In this study, the authors showed several cases in whom SPECT images of brain were not compatible with their neurologic deficits. In 2 typical cases, a large low-density area was observed in the non-dominant hemisphere in computed tomography (CT) scan, but no apparent motor-sensory deficits in left limbs were present. In these patients, SPECT study also revealed flow reduction in the affected side of the brain. So there was a possibility that an IMP brain image could not always reflect CBF, which maintains neurologic function of the brain.

Moriwaki, H.; Hougaku, H.; Matsuda, I.; Kusunoki, M.; Shirai, J. (Kobe Ekisaikai Hospital (Japan))

1989-08-01

338

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

PubMed

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

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

2011-11-01

339

Survival and Quality of Life after Arterial Revascularization or Major Amputation for Critical Leg Ischemia in Guadeloupe  

Microsoft Academic Search

Functional outcome and survival in 253 patients treated for critical leg ischemia (CLI) in Guadeloupe (French West Indies)\\u000a were analyzed. Analysis included calculation of quality-of-life score (QLS) from telephone survey data, with a median follow-up\\u000a time of 42 months (range 12-109). A slight but significant benefit was observed in the 140 patients who underwent arterial\\u000a reconstruction, with 76% autonomous ambulatory

Michel Deneuville; Arnauld Perrouillet

2006-01-01

340

Image quality of increased along-scan sampling for remote sensing systems  

Microsoft Academic Search

Commercial remote sensing systems generally employ a linear detector array for imaging the ground scene. Strategies for increasing the ground sampling along one direction of the array can be employed to improve the image quality. Image simulations were generated to quantify the image quality improvement, in terms of the National Image Interpretability Scale (NIIRS), as the sampling is increased in

Robert D. Fiete; Theodore A. Tantalo

1999-01-01

341

Use of low-dose contrast agent in cerebral angiography produces high-quality diagnostic images  

PubMed Central

The present study was aimed to study feasibility of low-dose contrast agent in cerebral CT angiography (CTA) to alleviate some side effects and costs associated with routine doses of contrast agent. Sixty patients suspected to have cerebral artery disease were randomly selected to receive either low-dose (60 mL) contrast agent or routine-dose (100 mL) contrast agent. CTA included transverse images, volume rendering (VR), and maximum intensity projection (MIP) images. Developing strength, image noise, and structure display effects of the cerebral artery were compared between groups. The developing strength and image noise of the cerebral artery were equivalent between groups (P > 0.05). No statistical differences were observed in structure display effects of the cerebral artery or in radiological diagnosis between groups (P > 0.05). Application of the low-dose contrast agent is feasible and offers comparable diagnostic capabilities in cerebral CT angiography.

Zhou, Yang; Chen, Mu-Nan; Liu, Yang

2014-01-01

342

Quality assessment of butter cookies applying multispectral imaging  

PubMed Central

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.

Andresen, Mette S; Dissing, Bj?rn S; L?je, Hanne

2013-01-01

343

Spread spectrum image watermarking based on perceptual quality metric.  

PubMed

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

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

2011-11-01

344

Note: A multifunction lens test system for imaging quality evaluation  

NASA Astrophysics Data System (ADS)

A novel multifunction lens imaging quality test system is established to overcome the practical problems in the conventional system. This system is compact, cost efficient, user friendly, and suitable for lens quality control in production line. The established system can evaluate the modulation transform function, imaging depth, image distortion, and light intensity distribution of the tested lens by auto-changing the tested patterns. This system consists of a tested lens, a charge coupled device (CCD) camera, a linear motorized stage, a system fixture, an observer liquid crystal display (LCD) monitor, and a notebook for providing patterns. The LCD monitor displays a series of specified tested patterns sent from the notebook. Then each displayed pattern goes through the tested lens and images in the CCD camera. Consequently, the performance of the tested lens can be evaluated by analyzing the image of CCD camera with special designed software. The advantage of this system is that it can complete a whole test quickly without interruption part replacement because the tested patterns are statically displayed on LCD monitor and controlled by the notebook.

Chen, Chun-Jen; Wu, Wen-Hong; Huang, Kuo-Cheng

2010-01-01

345

Improving SEM image quality using pixel super resolution technique  

NASA Astrophysics Data System (ADS)

The most decent scanning electron microscopy (SEM) can provide image magnification up to 500kX which seems to be suitable to image semiconductor devices for the advanced technology nodes. However, SEM images at such a high magnification often suffer from the drift and space related displacement errors, potentially causing image blur and distortion. To circumvent this, we apply the super-resolution (SR) technique to enhance the resolution of the CD-SEM metrology by using the advanced signal processing algorithms. The resolution enhancement can be realized by exploiting the multiple low resolution (LR) images that include unique information of an imaging target by looking at a slightly different position. We experimentally demonstrate image quality improvement gained by the SR technique after correcting the time-dependent drift/displacement and mapping estimated information onto the high resolution (HR) pixel grid with the non-linear pixel interpolation scheme. In addition, estimating the time-dependent drifts of the wafer position could be useful to investigate the drift properties of the CD-SEM tool.

Lee, Myungjun; Cantone, Jason; Xu, Ji; Sun, Lei; Kim, Ryoung-han

2014-04-01

346

A quality assurance program for image quality of cone-beam CT guidance in radiation therapy  

SciTech Connect

The clinical introduction of volumetric x-ray image-guided radiotherapy systems necessitates formal commissioning of the hardware and image-guided processes to be used and drafts quality assurance (QA) for both hardware and processes. Satisfying both requirements provides confidence on the system's ability to manage geometric variations in patient setup and internal organ motion. As these systems become a routine clinical modality, the authors present data from their QA program tracking the image quality performance of ten volumetric systems over a period of 3 years. These data are subsequently used to establish evidence-based tolerances for a QA program. The volumetric imaging systems used in this work combines a linear accelerator with conventional x-ray tube and an amorphous silicon flat-panel detector mounted orthogonally from the accelerator central beam axis, in a cone-beam computed tomography (CBCT) configuration. In the spirit of the AAPM Report No. 74, the present work presents the image quality portion of their QA program; the aspects of the QA protocol addressing imaging geometry have been presented elsewhere. Specifically, the authors are presenting data demonstrating the high linearity of CT numbers, the uniformity of axial reconstructions, and the high contrast spatial resolution of ten CBCT systems (1-2 mm) from two commercial vendors. They are also presenting data accumulated over the period of several months demonstrating the long-term stability of the flat-panel detector and of the distances measured on reconstructed volumetric images. Their tests demonstrate that each specific CBCT system has unique performance. In addition, scattered x rays are shown to influence the imaging performance in terms of spatial resolution, axial reconstruction uniformity, and the linearity of CT numbers.

Bissonnette, Jean-Pierre; Moseley, Douglas J.; Jaffray, David A. [Radiation Medicine Program, Princess Margaret Hospital, 610 University Avenue, Toronto, Ontario M5G 2M9 (Canada)

2008-05-15

347

Image quality vs. sensitivity: fundamental sensor system engineering  

NASA Astrophysics Data System (ADS)

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

Schueler, Carl F.

2008-08-01

348

Association of arterial blood pressure and CPR quality in a child using three different compression techniques, a case report  

PubMed Central

A 2-year-old boy found in cardiac arrest secondary to drowning received standard CPR for 35 minutes and was transported to a tertiary hospital for rewarming from hypothermia. Chest compressions in hospital were started using two-thumb encircling hands technique. Subsequently two-thumbs direct sternal compression technique and after sternal force/depth sensor placement, chest compression with classic one-hand technique were done. By using CPR recording/feedback defibrillator, quantitative CPR quality data and invasive arterial pressures were available for analyses for 5 hours and 35 minutes. 316 compressions with the two-thumb encircling hands technique provided a mean (SD) systolic arterial pressure (SAP) of 24 (4) mmHg, mean arterial pressure (MAP) 18 (3) and diastolic arterial pressure (DAP) of 15 (3) mmHg. ~6000 compressions with the two thumbs direct compression technique created a mean SAP of 45 (7) mmHg, MAP 35 (4) mmHg and DAP of 30 (3) mmHg. ~20,000 compressions with the sternal accelerometer in place produced SAP 50 (10) mmHg, MAP 32 (5) mmHg and DAP 24 (4) mmHg. Restoration of spontaneous circulation (ROSC) was achieved at the point when the child achieved normothermia by using peritoneal dialysis. Unfortunately, the child died ten hours after ROSC without any signs of neurological recovery. This case demonstrates improved hemodynamic parameters with classic one-handed technique with real-time quantitative quality of CPR feedback compared to either the two-thumbs encircling hands or two-thumbs direct sternal compression techniques. We speculate that the improved arterial pressures were related to improved chest compression depth when a real-time CPR recording/feedback device was deployed. Trial registration ClinicalTrials.gov: NCT00951704.

2013-01-01

349

A Reduced Resolution Transit Delay Prescan for Quantitative Continuous Arterial Spin Labeling Perfusion Imaging  

PubMed Central

Arterial Spin Labeling (ASL) perfusion MRI can suffer from artifacts and quantification errors when the time delay between labeling and arrival of labeled blood in the tissue is uncertain. This transit delay is particularly uncertain in broad clinical populations, where reduced or collateral flow may occur. Measurement of transit delay by acquisition of the ASL signal at many different time delays typically extends the imaging time and degrades the sensitivity of the resulting perfusion images. Acquisition of transit delay maps at the same spatial resolution as perfusion images may not be necessary, however, because transit delay maps tend to contain little high spatial resolution information. Here, we propose the use of a reduced spatial resolution ASL prescan for the rapid measurement of transit delay. Approaches to using the derived transit delay information to optimize and quantify higher resolution continuous ASL perfusion images are described. Results in normal volunteers demonstrate heterogeneity of transit delay across different brain regions that lead to quantification errors without the transit maps and demonstrate the feasibility of this approach to perfusion and transit delay quantification.

Dai, Weiying; Robson, Philip M; Shankaranarayanan, Ajit; Alsop, David C.

2012-01-01

350

Spatial distribution of wall shear stress in common carotid artery by color Doppler flow imaging.  

PubMed

The purpose of this study is to provide a novel approach for measuring the spatial distribution of wall shear stress (WSS) in common carotid artery in vivo. WSS distributions were determined by digital image processing from color Doppler flow imaging (CDFI) in 50 healthy volunteers. In order to evaluate the feasibility of the spatial distribution, the mean values of WSS distribution were compared to the results of conventional WSS calculating method (Hagen-Poiseuille formula). In our study, the mean value of WSS distribution from 50 healthy volunteers was (6.91?±?1.20) dyne/cm(2), while it was (7.13?±?1.24) dyne/cm(2) by Hagen-Poiseuille approach. The difference was not statistically significant (t?=?-0.864, p?=?0.604). Hence, the feasibility of the spatial distribution of WSS was proved. Moreover, this novel approach could provide three-dimensional distribution of shear stress and fusion image of shear stress with ultrasonic image for each volunteer, which made WSS "visible". In conclusion, the spatial distribution of WSS could be used for WSS calculation in vivo. Moreover, it could provide more detailed values of WSS distribution than those of Hagen-Poiseuille formula. PMID:22832893

Wang, Chao; Chen, Ming; Liu, Sheng-lin; Liu, Yi; Jin, Jia-mei; Zhang, Yu-hui

2013-06-01

351

Functional Real-Time Optoacoustic Imaging of Middle Cerebral Artery Occlusion in Mice  

PubMed Central

Background and Purpose Longitudinal functional imaging studies of stroke are key in identifying the disease progression and possible therapeutic interventions. Here we investigate the applicability of real-time functional optoacoustic imaging for monitoring of stroke progression in the whole brain of living animals. Materials and Methods The middle cerebral artery occlusion (MCAO) was used to model stroke in mice, which were imaged preoperatively and the occlusion was kept in place for 60 minutes, after which optoacoustic scans were taken at several time points. Results Post ischemia an asymmetry of deoxygenated hemoglobin in the brain was observed as a region of hypoxia in the hemisphere affected by the ischemic event. Furthermore, we were able to visualize the penumbra in-vivo as a localized hemodynamically-compromised area adjacent to the region of stroke-induced perfusion deficit. Conclusion The intrinsic sensitivity of the new imaging approach to functional blood parameters, in combination with real time operation and high spatial resolution in deep living tissues, may see it become a valuable and unique tool in the development and monitoring of treatments aimed at suspending the spread of an infarct area.

Krieg, Sandro M.; Lehmberg, Jens; Lindauer, Ute; Razansky, Daniel

2014-01-01

352

Comparison of two common aerial reconnaissance image quality measures  

NASA Astrophysics Data System (ADS)

The assessment of imaging system performance is critical to ensuring a system is delivering the highest quality products possible. The principle two methods for evaluation of reconnaissance system performance are resolution and the National Imagery Interpretability Rating Scale (NIIRS). This paper describes both methods, and presents benefits and limitations of each. Use of the NIIRS is shown to be on the increase as it and an associated prediction model have been relatively recently released unclassified.

Riehl, Kenneth; Maver, Larry

1996-11-01

353

High image quality sub 100 picosecond gated framing camera development  

SciTech Connect

A major challenge for laser fusion is the study of the symmetry and hydrodynamic stability of imploding fuel capsules. Framed x-radiographs of 10-100 ps duration, excellent image quality, minimum geometrical distortion (< 1%), dynamic range greater than 1000, and more than 200 x 200 pixels are required for this application. Recent progress on a gated proximity focused intensifier which meets these requirements is presented.

Price, R.H.; Wiedwald, J.D.

1983-11-17

354

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

SciTech Connect

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

Wehrschuetz, M., E-mail: martin.wehrschuetz@klinikum-graz.at; Aschauer, M.; Portugaller, H.; Stix, A. [University Hospital Graz, Department of Radiology (Austria); Wehrschuetz-Sigl, E. [University Hospital Graz, Department of Angiology (Austria); Hausegger, K.; Ebner, F. [University Hospital Graz, Department of Radiology (Austria)

2004-09-15

355

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

SciTech Connect

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.

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

356

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

NASA Astrophysics Data System (ADS)

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

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

1998-04-01

357

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

NASA Astrophysics Data System (ADS)

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

Mitjà, Carles; Escofet, Jaume; Bover, Toni

2012-05-01

358

A mechanism for the management and optimization of imaging systems with non-uniform imaging quality  

NASA Astrophysics Data System (ADS)

When imaging data is collected using airborne remote sensing systems, it is common that the image quality (IQ) of the collected data is not uniform over the entire region of collection. This non-uniformity of IQ is often a limiting factor to the utility of collected data. It would therefore be useful to have a mechanism to predict, assess and manage the non-uniformity of the IQ of remote sensing data both before and after data collection. A mechanism is proposed to model spatially and temporally varying IQ aspects of an imaging collection as a matrix across the region of collection. Within this framework an image quality metric such as a NIIRS based IQE or other IQ predictor is applied to the matrix of parameters, thus sampling IQ such that a 'map' or 'picture' of image quality is created. This allows specific knowledge of IQ performance at particular locations in an image, allowing better resource management when multiple targets with separate collection requirements are collected in the same imaging event. Application to mission planning and optimization of system resources under contingency operations, such as when a system must operate in a degraded state, are also discussed.

Sanderson, Thomas A.; Sprague, Paul; Smith, Steven L.; Simmons, Rulon E.; Lines, Raymond T.

2005-05-01

359

Comparison of block matching and differential methods for motion analysis of the carotid artery wall from ultrasound images.  

PubMed

Motion of the carotid artery wall is important for the quantification of arterial elasticity and contractility and can be estimated with a number of techniques. In this paper, a framework for quantitative evaluation of motion analysis techniques from B-mode ultrasound images is introduced. Six synthetic sequences were produced using 1) a real image corrupted by Gaussian and speckle noise of 25 and 15 dB, and 2) the ultrasound simulation package Field II. In both cases, a mathematical model was used, which simulated the motion of the arterial wall layers and the surrounding tissue, in the radial and longitudinal directions. The performance of four techniques, namely optical flow (OF (HS)), weighted least-squares optical flow (OF (LK(WLS))), block matching (BM), and affine block motion model (ABMM), was investigated in the context of this framework. The average warping indices were lowest for OF (LK(WLS)) (1.75 pixels), slightly higher for ABMM (2.01 pixels), and highest for BM (6.57 pixels) and OF (HS) (11.57 pixels). Due to its superior performance, OF (LK(WLS)) was used to quantify motion of selected regions of the arterial wall in real ultrasound image sequences of the carotid artery. Preliminary results indicate that OF (LK(WLS)) is promising, because it efficiently quantified radial, longitudinal, and shear strains in healthy adults and diseased subjects. PMID:22491098

Golemati, Spyretta; Stoitsis, John S; Gastounioti, Aimilia; Dimopoulos, Alexandros C; Koropouli, Vassiliki; Nikita, Konstantina S

2012-09-01

360

Advanced imaging in colonoscopy and its impact on quality.  

PubMed

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

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

2014-01-01

361

The image quality of FBP and MLEM reconstruction  

NASA Astrophysics Data System (ADS)

We have developed an image quality theory for filtered back-projection (FBP) and maximum likelihood expectation maximization (MLEM) based on quality measures like signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), signal and noise power spectra and the detective quantum efficiency (DQE) concept. Analytic expressions are derived for unattenuated SPECT reconstruction with ideal collimation to obtain the fundamental performance parameters of different reconstruction algorithms. This theory is verified by measurements of signal and noise power on simulated phantoms. We demonstrate that the noise power of reconstructed images is proportional to the diameter of the object given as a number of voxels. This is analytically proven for FBP and clarified by assessment of the convergence properties for MLEM. The latter technique is shown to be superior to FBP in terms of a noise level at least two times lower. The free choice of MLEM reconstruction parameters and correction for physical effects in the image acquisition enables quantitative evaluation of SPECT and PET images.

Wieczorek, Herfried

2010-06-01

362

Image gathering and digital restoration for fidelity and visual quality  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

363

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

NASA Astrophysics Data System (ADS)

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.

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

2006-12-01

364

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

PubMed Central

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.

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

2008-01-01

365

Noninvasive Two-Dimensional Strain Imaging of Arteries: Validation in Phantoms and Preliminary Experience in Carotid Arteries In Vivo  

Microsoft Academic Search

Cardiac disease and stroke are the major causes of death in the Western World. Atherosclerosis of the carotid artery is the most important predictor of stroke. Elastography is a technique to assess the composition and vulnerability of an atherosclerotic plaque. Contrary to intravascular applications, the ultrasound beam and radial strain are not aligned in noninvasive acquisitions. In this study, 2D

Hermine Ribbers; Richard G. P. Lopata; Suzanne Holewijn; Gerard Pasterkamp; Jan D. Blankensteijn; Chris L. de Korte

2007-01-01

366

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

PubMed Central

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

2012-01-01

367

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

NASA Astrophysics Data System (ADS)

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.

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

2014-01-01

368

Impact of PVCs noted during coronary calcium scan on image quality and accuracy in subsequent coronary dual-source CT angiography.  

PubMed

The purpose of this study was to investigate the impact of the presence of one or more premature ventricular contractions (PVCs) during coronary calcium score scan (CS) on image quality and accuracy of subsequent dual-source coronary CT angiography (DS CCTA). Fifty-three out of 502 patients showed one or more PVCs during CS and built the study group. Sixty consecutively registered patients with sinus rhythm formed the control group. Two independent, blinded readers classified 1,723 coronary artery segments as being of diagnostic or non-diagnostic image quality. All segments with diagnostic image quality were assessed for the presence for significant coronary artery stenosis. Accuracy was calculated using conventional angiography as standard of reference. The percentage of DS CCTA data sets with diagnostic image quality was significantly lower in the study group (79.2%) compared to the control group (90.6%, P < 0.05). The rate of coronary segment with diagnostic image quality was highly significant lower in the study group (89.5%; n = 723/808) compared to the control group (99.4%; n = 908/915; P < 0.001). However, accuracy did not differ in both groups. Significant correlation between non-diagnostic image quality and mean HR was only found in the study group (P = 0.019). The presence of one or more PVCs during CS does not affect accuracy but impairs image quality of subsequent DS CCTA. Mean HR is a predictor of non-diagnostic data sets only in the study group, suggesting more aggressive HR control could be beneficial. PMID:20835764

Eicher, Wolfgang; Kau, Thomas; Niedermayer, Martin; Senft, Birgit; Sinzig, Maria; Strozyk, Birgit; Hausegger, Klaus Armin

2011-04-01

369

Evaluation of scatter effects on image quality for breast tomosynthesis  

SciTech Connect

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.

Wu Gang; Mainprize, James G.; Boone, John M.; Yaffe, Martin J. [Imaging Research, Sunnybrook Health Sciences Centre, S-657, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada) and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M4N 3M5 (Canada); Department of Medical Biophysics, University of Toronto, Toronto, Ontario M4N 3M5 (Canada); Department of Radiology, X-ray Imaging Laboratory, U. C. Davis Medical Center, 4701 X Street, Sacramento, California 95817 and Department of Biomedical Engineering, University of California, Davis, California 95616 (United States); Imaging Research, Sunnybrook Health Sciences Centre, S-657, 2075 Bayview Avenue, Toronto, Ontario M4N 3M5 (Canada) and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M4N 3M5 (Canada)

2009-10-15

370

Multivariate Statistical Analysis of Existing Image Quality Metrics Over Turbulent Images  

Microsoft Academic Search

State-of-the-art objective image quality metrics are summarized and analyzed from a new perspective. Performance comparisons of existing metrics are firstly conducted on simulated turbulence-degraded images. Then exploratory factor analysis method is used to uncover the latent relationships among existing metrics. Experimental results show that existing metrics are highly correlated to each other, and can be separated into four groups, each

Ming Li; Jie Yang

2009-01-01

371

Successful Magnetic Resonance Imaging-Guided Focused Ultrasound Surgery for Recurrent Uterine Fibroid Previously Treated with Uterine Artery Embolization  

PubMed Central

A 45-year-old premenopausal woman was referred to our clinic due to recurring symptoms of uterine fibroids, nine years after a uterine artery embolization (UAE). At the time of screening, the patient presented with bilateral impairment and narrowing of the uterine arteries, which increased the risk of arterial perforation during repeated UAE procedures. The patient was subsequently referred for magnetic resonance imaging-guided focused ultrasound surgery (MRgFUS) treatment. Following the treatment, the patient experienced a significant improvement in symptoms (symptom severity score was reduced from 47 to 12 by 1 year post-treatment). MR images at 3 months showed a 49% decrease in fibroid volume. There were no adverse events during the treatment or the follow-up period. This case suggests that MRgFUS can be an effective treatment option for patients with recurrent fibroids following previous UAE treatment.

Yoon, Sang-Wook; Kim, Kyoung Ah; Kim, Sang Heum; Lee, Jong Tae

2010-01-01

372

Quality and image restoration in secondary X-ray imaging, with human angiography as an example  

NASA Astrophysics Data System (ADS)

Secondary X-Ray Imaging was proposed because it requires less sophisticated X-ray sources, improves image quality, and may also decrease the needed primary X-ray intensity, compared with the well known KES method. A primary pencil beam rastered through the target creates secondary (fluorescent) X-rays, recorded by a wide detector. Detectors can be particularly sensitive to the secondaries, thus reducing the number of primaries needed. An inherent difficulty, is that most primary X-rays are scattered before reaching the target, forming a poorly focused halo, with a broad energy range. Here human angiography is chosen as an (especially demanding) example to show that high quality images can nevertheless be obtained: An analytical formula is derived simulating the effects of scattering, a phantom target with sharp edges is assumed, and a raw image is calculated. It is found that despite the scattered background the relevant features are well recognizable. If desired, image quality can be improved. To illustrate, a simple iterative algorithm is used to generate a final (improved) image.

Csonka, P. L.

2007-01-01

373

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

PubMed Central

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.

Yang, Na; Demirkol, Ilker; Heinzelman, Wendi

2013-01-01

374

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

PubMed

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

Yang, Na; Demirkol, Ilker; Heinzelman, Wendi

2012-01-01

375

Tracking Navigation Imaging of Transcatheter Arterial Chemoembolization for Hepatocellular Carcinoma Using Three-Dimensional Cone-Beam CT Angiography  

PubMed Central

Purpose New tracking navigation imaging software was used to evaluate the usefulness of three dimensional (3D) CT angiography for transcatheter arterial chemoembolization (TACE) in patients with hepatocellular carcinoma (HCC). Materials and Methods Fifty-two patients with 73 HCCs were enrolled in this study retrospectively. Rotational angiography was performed from the hepatic artery for evaluation of the tumor feeding vessels. Arteries feeding the tumor were traced automatically by adjusting the region of interest around the targeted tumor on axial and coronal images using tracking navigation imaging with 3D cone-beam CT angiography. Results Using final selective angiographic findings as the gold standard, the detection of feeding vessels was 90.4% (66/73) for tracking navigation imaging and 50.7% (37/73) for celiac trunk angiography. This difference was statistically significant (Wilcoxon rank sum test, p < 0.001). The sensitivity, specificity, positive predictive value, and negative predictive value for the detection of feeding arteries were 97.1% (66/68), 80.0% (4/5), 98.5% (66/67), and 66.7% (4/6), respectively. The kappa coefficient had a value of 0.638 (95% CI: 0.471-0.805), which is considered to indicate a good degree of agreement. With the assistance of tracking navigation imaging, the disease control rate of TACE for HCC was 67.3% (35/52) according to the modified Response Evaluation Criteria in Solid Tumors. During follow-up periods of 1-11 months, 10 patients (19.2%) remained cancer-free after TACE. Conclusion: Tracking navigation imaging with 3D cone-beam CT angiography should be useful for TACE in HCC patients with complicated feeding arteries.

Minami, Yasunori; Yagyu, Yukinobu; Murakami, Takamichi; Kudo, Masatoshi

2014-01-01

376

Assessing and improving cobalt-60 digital tomosynthesis image quality  

NASA Astrophysics Data System (ADS)

Image guidance capability is an important feature of modern radiotherapy linacs, and future cobalt-60 units will be expected to have similar capabilities. Imaging with the treatment beam is an appealing option, for reasons of simplicity and cost, but the dose needed to produce cone beam CT (CBCT) images in a Co-60 treatment beam is too high for this modality to be clinically useful. Digital tomosynthesis (DT) offers a quasi-3D image, of sufficient quality to identify bony anatomy or fiducial markers, while delivering a much lower dose than CBCT. A series of experiments were conducted on a prototype Co-60 cone beam imaging system to quantify the resolution, selectivity, geometric accuracy and contrast sensitivity of Co-60 DT. Although the resolution is severely limited by the penumbra cast by the ~2 cm diameter source, it is possible to identify high contrast objects on the order of 1 mm in width, and bony anatomy in anthropomorphic phantoms is clearly recognizable. Low contrast sensitivity down to electron density differences of 3% is obtained, for uniform features of similar thickness. The conventional shift-and-add reconstruction algorithm was compared to several variants of the Feldkamp-Davis-Kress filtered backprojection algorithm result. The Co-60 DT images were obtained with a total dose of 5 to 15 cGy each. We conclude that Co-60 radiotherapy units upgraded for modern conformal therapy could also incorporate imaging using filtered backprojection DT in the treatment beam. DT is a versatile and promising modality that would be well suited to image guidance requirements.

Marsh, Matthew B.; Schreiner, L. John; Kerr, Andrew T.

2014-03-01

377

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

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.

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

2014-01-01

378

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

PubMed Central

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.

2010-01-01

379

Imaging Stem Cell Therapy for the Treatment of Peripheral Arterial Disease  

PubMed Central

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

Ransohoff, Julia D.; Wu, Joseph C.

2013-01-01

380

Completely blind image quality assessment based on gray-scale fluctuations  

NASA Astrophysics Data System (ADS)

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.

Yang, Xichen; Sun, Quansen; Wang, Tianshu

2014-04-01

381

Prospective Analysis of Cerebral Infarction After Carotid Endarterectomy and Carotid Artery Stent Placement by Using Diffusion-Weighted Imaging  

Microsoft Academic Search

BACKGROUND AND PURPOSE: Small emboli arising from a friable plaque during carotid endarterectomy (CEA) and carotid artery stent placement (CAS) constitute a potentially important cause of periprocedural ischemic complications. To evaluate the frequency and significance of cerebral ischemic lesions of embolic origin after CEA and CAS, we examined patients with moderate to severe carotid stenosis by using diffusion-weighted (DW) imaging.

Hong Gee Roh; Hong Sik Byun; Jae Wook Ryoo; Dong Gyu Na; Won-Jin Moon; Byung Boong Lee; Dong-Ik Kim

382

SPY™: an innovative intra-operative imaging system to evaluate graft patency during off-pump coronary artery bypass grafting  

Microsoft Academic Search

Off-pump coronary artery bypass grafting (CABG) has been rapidly increased, because of its less invasiveness with low complications. However, graft patency rate highly depends on the operators' capability due to technical difficulties. The SPY™ system, based on the fluorescence of indocyanine green, is an innovative device that permits validation of graft patency intra-operatively. Real time images of grafts are obtained

Masao Takahashi; Toshihiro Ishikawa; Koichi Higashidani; Hiroki Katoh

2004-01-01

383

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

NASA Astrophysics Data System (ADS)

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.

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

2012-02-01

384

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

PubMed

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

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

2014-07-01

385

Regional and Global Biventricular Function in Pulmonary Arterial Hypertension: A Cardiac MR Imaging Study  

PubMed Central

Purpose: To determine whether chronic pulmonary arterial pressure (PAP) elevation affects regional biventricular function and whether regional myocardial function may be reduced in pulmonary arterial hypertension (PAH) patients with preserved global right ventricular (RV) function. Materials and Methods: After informed consent, 35 PAH patients were evaluated with right heart catheterization and cardiac magnetic resonance (MR) imaging and compared with 13 healthy control subjects. Biventricular segmental, section, and mean ventricular peak systolic longitudinal strain (ELL), as well as left ventricular (LV) circumferential and RV tangential strains were compared between PAH patients and control subjects and correlated with global function and catheterization of the right heart indexes. Spearman ? correlation with Bonferroni correction was used. Multiple linear regression analysis was performed to determine predictors for regional myocardial function. Results: In the RV of PAH patients, longitudinal contractility was reduced at the basal, mid, and apical levels, and tangential contractility was reduced at the midventricular level. Mean RV ELL positively correlated with mean PAP (r = 0.62, P < .0014) and pulmonary vascular resistance index (PVRI) (r = 0.77, P < .0014). Mean PAP was a predictor of mean RV ELL (? = .19, P = .005) in a multiple linear regression analysis. In the LV, reduced LV longitudinal and circumferential contractility were noted at the base. LV anteroseptal ELL positively correlated with increased mean PAP (r = 0.5, P = .03) and septal eccentricity index (r = 0.5, P = .01). In a subgroup of PAH patients with normal global RV function, significantly reduced RV longitudinal contractility was noted at basal and mid anterior septal insertions, as well as the mid anterior RV wall (P < .05 for all). Conclusion: In PAH patients, reduced biventricular regional function is associated with increased RV afterload (mean PAP and PVRI). Cardiac MR imaging helps identify regional RV dysfunction in PAH patients with normal global RV function. © RSNA, 2012 Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12111599/-/DC1

Shehata, Monda L.; Harouni, Ahmed A.; Skrok, Jan; Basha, Tamer A.; Boyce, Danielle; Lechtzin, Noah; Mathai, Stephen C.; Girgis, Reda; Osman, Nael F.; Lima, Joao A. C.; Bluemke, David A.; Hassoun, Paul M.

2013-01-01

386

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

Microsoft Academic Search

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

H. Ohtani; N. Tamaki; Y. Yonekura; I. H. Mohiuddin; K. Hirata; T. Ban; J. Konishi

1990-01-01

387

No reference image quality assessment for JPEG2000 based on spatial features  

Microsoft Academic Search

Perceptual image quality evaluation has become an important issue, due to increasing transmission of multimedia contents over the Internet and 3G mobile networks. Most of the no reference perceptual image quality evaluations traditionally attempted to quantify the predefined artifacts of the coded images. Under the assumption that human visual perception is very sensitive to edge information of an image and

Parvez Z. M. Sazzad; Yoshikazu Kawayoke; Yuukou Horita

2008-01-01

388

Speckle pattern quality assessment for digital image correlation  

NASA Astrophysics Data System (ADS)

To perform digital image correlation (DIC), each image is divided into groups of pixels known as subsets or interrogation cells. Larger interrogation cells allow greater strain precision but reduce the spatial resolution of the data field. As such the spatial resolution and measurement precision of DIC are limited by the resolution of the image. In the paper the relationship between the size and density of speckles within a pattern is presented, identifying that the physical properties of a pattern have a large influence on the measurement precision which can be obtained. These physical properties are often overlooked by pattern assessment criteria which focus on the global image information content. To address this, a robust morphological methodology using edge detection is devised to evaluate the physical properties of different speckle patterns with image resolutions from 23 to 705 pixels/mm. Trends predicted from the pattern property analysis are assessed against simulated deformations identifying how small changes to the application method can result in large changes in measurement precision. An example of the methodology is included to demonstrate that the pattern properties derived from the analysis can be used to indicate pattern quality and hence minimise DIC measurement errors. Experiments are described that were conducted to validate the findings of morphological assessment and the error analysis.

Crammond, G.; Boyd, S. W.; Dulieu-Barton, J. M.

2013-12-01

389

Channelling optics for high quality imaging of sensory hair  

NASA Astrophysics Data System (ADS)

A long distance microscope (LDM) is extended by a lens and aperture array. This newly formed channelling LDM is superior in high quality, high-speed imaging of large field of views (FOV). It allows imaging the same FOV like a conventional LDM, but at improved magnification. The optical design is evaluated by calculations with the ray tracing code ZEMAX. High-speed imaging of a 2 × 2 mm2 FOV is realized at 3.000 frames per second and 1 ?m per pixel image resolution. In combination with flow sensitive hair the optics forms a wall shear stress sensor. The optics images the direct vicinity of twenty-one flow sensitive hair distributed in a quadratic array. The hair consists of identical micro-pillars that are 20 ?m in diameter, 390 ?m in length and made from polydimethylsiloxane (PDMS). Sensor validation is conducted in the transition region of a wall jet in air. The wall shear stress is calculated from optically measured micro-pillar tip deflections. 2D wall shear stress distributions are obtained with currently highest spatiotemporal resolution. The footprint of coherent vortical structures far away from the wall is recovered in the Fourier spectrum of wall shear stress fluctuations. High energetic patterns of 2D wall shear stress distributions are identified by proper orthogonal decomposition (POD).

Skupsch, C.; Klotz, T.; Chaves, H.; Brücker, C.

2012-04-01

390

Evaluating health-related quality of life, work ability, and disability in pulmonary arterial hypertension: an unmet need.  

PubMed

To our knowledge, there are no specific and validated measures of quality of life (QoL) or degree of disability for pulmonary arterial hypertension (PAH). A review of the literature shows that, with the exception of one recently designed specifically for pulmonary hypertension, QoL questionnaires used in PAH studies are generic measures. These are selected because of shared symptoms that do not necessarily correlate well with functional or physiologic measures and have not been validated for applicability in PAH. In this review, we present the available QoL tools for pulmonary artery hypertension and describe the need for more specific instruments that consider the physical and emotional implications of the diseases associated with PAH and the impact of various treatment options. We also discuss the impact of PAH on work ability and the need for provisions to address medical disability status and Social Security benefit status. PMID:19666759

Rubenfire, Melvyn; Lippo, Giuseppina; Bodini, Bruno D; Blasi, Francesco; Allegra, Luigi; Bossone, Eduardo

2009-08-01

391

Image fusion quality assessment based on discrete cosine transform and human visual system  

NASA Astrophysics Data System (ADS)

With the rapid development of image fusion technology, image fusion quality evaluation plays a very important guiding role in selecting or designing image fusion algorithms. Objective image quality assessment is an interesting research subject in the field of image quality assessment. The ideal objective evaluation method is consistent with human perceptual evaluation. A new fusion image quality assessment method according with human vision system and discrete cosine transform (DCT) is introduced. Firstly, using the Sobel operator to calculate to gradient images for the source images and fused image, the gradient images are divided into 8×8 blocks and calculating the DCT coefficients for each block, and then based on the characteristics of human visual system, calculates the luminance masking, contrast masking to form the perceptual error matrix between input images and fused images. Finally, weighs the perceptual error matrix using the structural similarity. Experiments demonstrate that the new assessment maintains better consistency with human subjective perception.

Dou, Jianfang; Li, Jianxun

2012-09-01

392

Image quality and attenuation values of multi detector CT coronary angiography using high iodine-concentration contrast material: A comparison of the use of iopromide 370 and iomeprol 400  

PubMed Central

Background: Effects of high iodine-concentration contrast material on the image quality of coronary CT angiography (CCTA) have not been well evaluated. Purpose: To compare the image quality and attenuation values of CCTA between patients administered iopromide 370 and iomeprol 400 with the use of 64-slice multidetector CT. Material and Methods: Patients were prospectively enrolled and were randomized into two groups (group A, 151 patients received iopromide 370, iodine flux = 1.48 g I/s; group B, 146 patients received iomeprol 400, iodine flux = 1.60 g I/s). CT attenuation was measured in the coronary arteries and great arteries and measurements were standardized based on an iodine flux of 1.5 0 g I/s. The image quality of 15 coronary artery segments was graded by two radiologists in consensus with the use of a four-point scale (1 = excellent to 4 = poor enhancement). Non-parametric statistical approaches were used to compare the two groups. Results: The median attenuation values in the coronary arteries were 454 HU and 464 HU for iopromide 370 and iomeprol 400, respectively, and they did not differ (P = 0.26). When standardizing for an iodine flux, significantly higher attenuation values were found for iopromide 370 (median = 460 HU, range = 216-791 HU) compared with iomeprol 400 (median = 435 HU, range = 195—758 HU) (P = 0.006). The median image quality score of coronary arterial segments was 1 (range 1—2) for both groups (P = 0.84). Conclusion: The attenuation values in the coronary arteries after injection of the same amount of two high iodine-concentration contrast materials at the same flow rate with different iodine fluxes are similar with no difference in image quality. With standardization for an iodine flux, the attenuation is significantly higher when using iopromide 370.

Kim, Eun Young; Yeh, Dae Wook; Choe, Yeon Hyeon; Lee, Won Jae; Lim, Hyo Keun

2010-01-01