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1

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

PubMed

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

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

2014-08-01

2

Imaging the vertebral artery  

Microsoft Academic Search

Although conventional intraarterial digital subtraction angiography remains the gold standard method for imaging the vertebral artery, noninvasive modalities such as ultrasound, multislice computed tomographic angiography and magnetic resonance angiography are constantly improving and are playing an increasingly important role in diagnosing vertebral artery pathology in clinical practice. This paper reviews the current state of vertebral artery imaging from an evidence-based

Keng Yeow Tay; Jean Marie U-King-Im; Rikin A. Trivedi; Nicholas J. Higgins; Justin J. Cross; John R. Davies; Peter L. Weissberg; Nagui M. Antoun; Jonathan H. Gillard

2005-01-01

3

Relationship between beat to beat coronary artery motion and image quality in prospectively ECG-gated two heart beat 320-detector row coronary CT angiography  

Microsoft Academic Search

The objective was to investigate the influence of the beat-to-beat movement of the coronary arteries on image quality of multi-segment\\u000a reconstruction (MSR) images. Although MSR improves temporal resolution, image quality would be degraded by beat-to-beat movement\\u000a of the coronary arteries. In a retrospectively review, 18 patients (mean age, 67.0 years) who underwent coronary CT angiography\\u000a using a 320-detector row CT were

Nobuo Tomizawa; Shuhei Komatsu; Masaaki Akahane; Rumiko Torigoe; Shigeru Kiryu; Kuni Ohtomo

4

256-Slice CT Angiographic Evaluation of Coronary Artery Bypass Grafts: Effect of Heart Rate, Heart Rate Variability and Z-Axis Location on Image Quality  

PubMed Central

Purpose The objective of this study is to assess the effect of heart rate, heart rate variability and z-axis location on coronary artery bypass graft (CABG) image quality using a 256-slice computed tomography (CT) scanner. Methods A total of 78 patients with 254 CABG (762 graft segments) were recruited to undergo CABG assessment with 256-slice CT and prospective ECG-gating. Two observers rated graft segments for image quality on a 5-point scale. Quantitative measurements were also made. Logistic and cumulative link mixed models were used to assess the predictors of graft image quality. Results Graft image quality was judged as diagnostic (scores 5 (excellent), 4 (good) and 3 (moderate)) in 96.6% of the 762 segments. Interobserver agreement was excellent (kappa ?0.90). Graft image quality was not affected by heart rate level. However, high heart rate variability was associated with an important and significant image quality deterioration (odds ratio 4.31; p ?=? 0.036). Distal graft segments had significantly lower image quality scores than proximal segments (p ? 0.02). Significantly higher noise was noted at the origin of the mammary grafts (p ?=? 0.001), owing to streak artifacts from the shoulders. Conclusion CABG imaging with 270-msec rotation 256-slice CT and prospective ECG-gating showed an adequate image quality in 96.6% of graft segments, and an excellent interobserver agreement. Graft image quality was not influenced by heart rate level. Image quality scores were however significantly decreased in patients with high heart rate variability, as well as in distal graft segments, which are closer to the heart. PMID:24637891

Gramer, Bettina M.; Diez Martinez, Patricia; Chin, Anne S.; Sylvestre, Marie-Pierre; Larrivee, Sandra; Stevens, Louis-Mathieu; Noiseux, Nicolas; Soulez, Gilles; Rummeny, Ernst J.; Chartrand-Lefebvre, Carl

2014-01-01

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 ... blood to the heart can slow or stop, causing chest pain (stable ...

6

Coronary artery stent (image)  

MedlinePLUS

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

7

Social image quality  

NASA Astrophysics Data System (ADS)

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

Qiu, Guoping; Kheiri, Ahmed

2011-01-01

8

Imaging of a Cilioretinal Artery Embolisation  

PubMed Central

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

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

2014-01-01

9

Imaging Characteristics of Symptomatic Vertebral Artery Dissection: A Systematic Review  

PubMed Central

Background Vertebral artery dissection (VAD) is an important cause of stroke in the young. VAD can present with a range of imaging findings. We sought to summarize the diagnostic value of various imaging findings in patients with symptomatic VAD. Methods We conducted a systematic review of observational studies, searching electronic databases (MEDLINE, EMBASE) for English-language manuscripts with >5 subjects with clinical or radiological features of VAD. Two independent reviewers selected studies for inclusion; a third adjudicated differences. Studies were assessed for methodological quality and imaging data were abstracted. Pooled proportions were calculated. Results Of 3996 citations, we screened 511 manuscripts and selected 75 studies describing 1,972 VAD patients. Most studies utilized conventional angiography or magnetic resonance angiography (MRA) to diagnose VAD; CT angiography (CTA) and Doppler ultrasonography were described less frequently. Imaging findings reported were vertebral artery stenosis (51%), string and pearls (48%), arterial dilation (37%), arterial occlusion (36%), and pseudoaneurysm, double lumen, and intimal flap (22% each). In cases where conventional angiography was the reference standard, CTA was more sensitive (100%) than either MRA (77%) or Doppler ultrasonography (71%) (p=0.001). Conclusions Imaging findings vary widely in patients with VAD, with no single radiographic sign present in the majority of VAD patients. Non-specific radiographic signs predominate. CTA probably has greater sensitivity for dissection than MRA or ultrasound relative to conventional angiography. Higher quality studies on imaging techniques and radiographic criteria in subjects with VAD are needed. Future studies should compare imaging techniques in well-defined, undifferentiated populations of clinical VAD suspects. PMID:22931729

Gottesman, Rebecca F.; Sharma, Priti; Robinson, Karen A.; Arnan, Martinson; Tsui, Megan; Saber-Tehrani, Ali; Newman-Toker, David E.

2013-01-01

10

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

11

[The importance of combining ultrasonography of the carotid artery bifurcation and Doppler imaging of cerebral arteries].  

PubMed

The USG of carotid bifurcation and Doppler imaging of cranial arteries were performed in 74 patients with ischaemic stroke. The Doppler image as well as USG were found to be helpful for prognosis. Arteriosclerotic USG changes corresponded more often with the neurological syndrome in severely ill patients (at discharge from hospital). Also reduction of flow in medial cerebral artery was significantly more often in these patients in the first hours of the illness. In thrombosis of the first part of the internal carotid artery only the succeeding image can indicate it (2 cases). Arteriography only can demonstrate artery tortuosity (1 case). PMID:8164774

Wiszniewska, M; Jankowska-Rózy?ska, M; Wiszniewski, P; Wojnowski, L

1993-01-01

12

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

13

Segmentation of coronary arteries from CT angiography images  

NASA Astrophysics Data System (ADS)

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

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

2007-03-01

14

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

15

Intravascular Optical Imaging Technology for Investigating the Coronary Artery  

PubMed Central

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

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

2012-01-01

16

Intravascular optical imaging technology for investigating the coronary artery.  

PubMed

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

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

2011-09-01

17

Optimizing image quality for SAR  

NASA Technical Reports Server (NTRS)

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.

1984-01-01

18

Video and image quality  

NASA Astrophysics Data System (ADS)

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

Aldridge, Jim

1995-09-01

19

[Non invasive imaging of bilateral vertebral arteries agenesis].  

PubMed

Imaging descriptions are lacking for vertebral artery variants reported in the anatomy literature. We report thus a variant of vertebral arteries discovered incidentally in a patient admitted for aortocoronary bypass. Doppler of the supra-aortic arches revealed the absence of cervical segments of both vertebral arteries. Transcranial doppler revealed the presence of intracranial segments of these arteries that continued in a normal basilar trunk. MR-angiography performed on a 3T machine confirmed the bilateral absence of cervical segments and the presence of normal intracranial segments arising from the occipital arteries, branches of the external carotid arteries. Embryologic analysis explains this variant by an involution of cervical segments and persistence of anastomoses between the external carotid system and the vertebrobasilar system that normally regresses during fetal life. This anastomosis enables irrigation of the intracranial vertebrobasilar system by the external carotid artery. The introduction of 3T MR-angiography has enabled better and more precise detection of vascular variants without invasive angiography. PMID:18313873

Hachem, K; Abi Khalil, S; Slaba, S; Jebara, V; Ghossain, M

2008-02-01

20

Molecular analysis of arterial remodeling: a novel application of infrared imaging  

NASA Astrophysics Data System (ADS)

Arterial remodeling, i.e. changes in size and/or structure of arteries, plays an important role in vascular disease. Conflicting findings have been reported as to whether an abundance of collagen causes inward or outward remodeling, phenomena that result in either a smaller or larger lumen, respectively. We hypothesize that the amount, type and quality of collagen influence the remodeling response. Here, we create mechanical injury to the rat carotid artery using a balloon catheter, and this leads to inward remodeling. Treatment of the artery with Connective Tissue Growth Factor (CTGF) causes outward remodeling. We investigated the arterial composition in injured CTGF-treated and non-CTGF-treated and sham CTGF-treated and non-CTGF treated arteries 14 days post-injury (n = 7-8 per group) using infrared imaging. A Perkin Elmer Spotlight Spectrum 300 FT-IR microscope was used for data collection. Cross-sections of paraffinembedded arteries were scanned at 2 cm-1 spectral resolution with spatial resolution of 6.25 ?m/pixel, and data analyzed using Malvern Instruments ISys 5.0. Post-injury, we found a nearly 50% reduction in the average 1338/AM2 area ratio (correlated to collagen helical integrity). The most dramatic change was a 600% increase in the 1660/1690 peak height ratio, which has previously been related to collagen crosslink maturity. In all cases, CTGF treatment resulted in the observed changes in peak parameters normalized back to control values. Overall, these preliminary studies demonstrate that infrared imaging can provide insight into the underlying molecular changes that contribute to arterial disease.

Herman, Brad C.; Kundi, Rishi; Yamanouchi, Dai; Kent, K. Craig; Liu, Bo; Pleshko, Nancy

2009-02-01

21

NMR (Nuclear Magnetic Resonance) Imaging of Human Coronary Arteries.  

National Technical Information Service (NTIS)

Nuclear magnetic resonance imaging (MRI) is being studied as a method to detect the presence of atherosclerotic lesions in the coronary arteries of humans in a totally non-invasive manner, and to characterize the anatomic features of these lesions. For th...

L. Kaufman, L. Crooks, C. Higgins, J. Hale

1984-01-01

22

Evaluation of temporal windows for coronary artery bypass graft imaging with 64-slice CT  

Microsoft Academic Search

Temporal windows providing the best image quality of different segments and types of coronary artery bypass grafts (CABGs)\\u000a with 64-slice computed tomography (CT) were evaluated in an experimental set-up. Sixty-four-slice CT with a rotation time\\u000a of 330 ms was performed in 25 patients (four female; mean age 59.9 years). A total of 84 CABGs (62 individual and 22 sequential\\u000a grafts) were evaluated,

Lotus Desbiolles; Sebastian Leschka; André Plass; Hans Scheffel; Lars Husmann; Oliver Gaemperli; Elisabeth Garzoli; Borut Marincek; Philipp A. Kaufmann; Hatem Alkadhi

2007-01-01

23

Image quality assessment for performance evaluation of image fusion  

Microsoft Academic Search

We present a novel approach on objective non-reference image fusion performance assessment. The Global-Local Image Quality Analysis (GLIQA) approach takes into account local measurements to estimate how well the important information in the source images is represented by the fused image. The metric is an extended version of the Universal Image Quality Index (UIQI) and uses the similarity between blocks

Erik Blasch; Xiaokun Li; Genshe Chen; Wenhua Li

2008-01-01

24

Quantitative image analysis of histological sections of coronary arteries  

NASA Astrophysics Data System (ADS)

The study of coronary arteries has evolved from examining gross anatomy and morphology to scrutinizing micro-anatomy and cellular composition. Technological advances such as high- resolution digital microscopes and high precision cutting devices have allowed examination of coronary artery morphology and pathology at micron resolution. We have developed a software toolkit to analyze histological sections. In particular, we are currently engaged in examining normal coronary arteries in order to provide the foundation for study of remodeled tissue. The first of two coronary arteries was stained for elastin and collagen. The second coronary artery was sectioned and stained for cellular nuclei and smooth muscle. High resolution light microscopy was used to image the sections. Segmentation was accomplished initially with slice- to-slice thresholding algorithms. These segmentation techniques choose optimal threshold values by modeling the tissue as one or more distributions. Morphology and image statistics were used to further differentiate the thresholded data into different tissue categories therefore refine the results of the segmentation. Specificity/sensitivity analysis suggests that automatic segmentation can be very effective. For both tissue samples, greater than 90% specificity was achieved. Summed voxel projection and maximum intensity projection appear to be effective 3-D visualization tools. Shading methods also provide useful visualization, however it is important to incorporate combined 2-D and 3-D displays. Surface rendering techniques (e.g. color mapping) can be used for visualizing parametric data. Preliminary results are promising, but continued development of algorithms is needed.

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

2000-06-01

25

The Research of Image Quality Assessment Methods  

NASA Astrophysics Data System (ADS)

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

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

26

Image Fusion Quality Metrics by Directional Projection  

Microsoft Academic Search

Image fusion has been over-studied recently. Nevertheless, few works aim to how to evaluate the performance of image fusion algorithms. In this paper, we extend the work in image quality evaluation to a novel metric for objective evaluation of image fusion. Firstly the input images and the result image are converted into local sensitive intensity (LSI) by Radon transform. Then

Richang Hong; Yan Song; Jinhui Tang; Jianxin Pang

2009-01-01

27

ECG-synchronized DSA exposure control: improved cervicothoracic image quality  

SciTech Connect

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

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

1984-10-01

28

Integrative computed tomographic imaging of coronary artery disease.  

PubMed

Rapid technological evolution in multislice computed tomography (CT) over the last decade with improved spatial and temporal resolution has enabled cardiac CT to become a viable and effective alternative in the diagnosis of coronary artery disease. Within recent years CT coronary angiography has demonstrated high sensitivity and specificity, and in particular a very high negative-predictive value, making it a valuable imaging modality for ruling out suspected coronary artery disease. In addition, CT angiography demonstrates accuracy in the detection and characterization of coronary plaques, and it has been reported to play an important role in predicting disease progression and cardiac events. The goal of this article is to provide an overview on the role and current clinical applications of cardiac CT in the evaluation of coronary artery disease. Emerging areas of cardiac CT, including dual-energy CT and CT myocardial perfusion are also discussed, as well as the limitations and future directions of cardiac CT. PMID:21166527

Weininger, Markus; Renker, Matthias; Rowe, Garret W; Abro, Joseph A; Costello, Philip; Schoepf, U Joseph

2011-01-01

29

Fused monochromatic imaging acquired by single source dual energy CT in hepatocellular carcinoma during arterial phase: an initial experience  

PubMed Central

Objective To explore whether single and fused monochromatic images can improve liver tumor detection and delineation by single source dual energy CT (ssDECT) in patients with hepatocellular carcinoma (HCC) during arterial phase. Methods Fifty-seven patients with HCC who underwent ssDECT scanning at Beijing Cancer Hospital were enrolled retrospectively. Twenty-one sets of monochromatic images from 40 to 140 keV were reconstructed at 5 keV intervals in arterial phase. The optimal contrast-noise ratio (CNR) monochromatic images of the liver tumor and the lowest-noise monochromatic images were selected for image fusion. We evaluated the image quality of the optimal-CNR monochromatic images, the lowest-noise monochromatic images and the fused monochromatic images, respectively. The evaluation indicators included the spatial resolution of the anatomical structure, the noise level, the contrast and CNR of the tumor. Results In arterial phase, the anatomical structure of the liver can be displayed most clearly in the 65-keV monochromatic images, with the lowest image noise. The optimal-CNR monochromatic images of HCC tumor were 50-keV monochromatic images in which the internal structural features of the liver tumors were displayed most clearly and meticulously. For tumor detection, the fused monochromatic images and the 50-keV monochromatic images had similar performances, and were more sensitive than 65-keV monochromatic images. Conclusions We achieved good arterial phase images by fusing the optimal-CNR monochromatic images of the HCC tumor and the lowest-noise monochromatic images. The fused images displayed liver tumors and anatomical structures more clearly, which is potentially helpful for identifying more and smaller HCC tumors. PMID:25232217

Gao, Shun-Yu; Cui, Yong; Sun, Ying-Shi; Tang, Lei; Li, Xiao-Ting; Zhang, Xiao-Yan; Shan, Jun

2014-01-01

30

Adaptive fingerprint image enhancement with fingerprint image quality analysis  

E-print Network

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

Cho, Sung-Bae

31

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

32

Power Doppler imaging in the evaluation of extracranial vertebral artery compression in patients with vertebrobasilar insufficiency  

Microsoft Academic Search

Objective: The recent introduction of Power Doppler Imaging (PDI) made a promise for better visualization of blood vessels lying in regions anatomically difficult for ultrasound imaging, i.e. vertebral arteries. The purpose of our study was to assess usefulness of PDI technique in visualization of vertebral artery course and to assess its utility in the detecting spondylotic vertebral artery compression in

T. Jargiello; R. Pietura; P. Rakowski; M. Szczerbo-Trojanowska; M. Szajner; M. Janczarek

1998-01-01

33

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. PMID:22530177

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

2012-01-01

34

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. PMID:24976911

Jegere, Sanda; Narbute, Inga; Erglis, Andrejs

2014-01-01

35

A new quality metric for image fusion  

Microsoft Academic Search

We present three variants of a new quality metric for image fusion. The interest of our metrics, which are based on an image quality index recently introduced by Wang and Bovik in {[Z.} Wang et al., March 2002], lies in the fact that they do not require a ground-truth or reference image. We perform several simulations which show that our

Gemma Piella; Henk J. A. M. Heijmans

2003-01-01

36

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

37

Dual-source CT coronary imaging in heart transplant recipients: image quality and optimal reconstruction interval  

Microsoft Academic Search

The image quality and optimal reconstruction interval for coronary arteries in heart transplant recipients undergoing non-invasive\\u000a dual-source computed tomography (DSCT) coronary angiography was evaluated. Twenty consecutive heart transplant recipients\\u000a who underwent DSCT coronary angiography were included (19 male, one female; mean age 63.1?±?10.7 years). Data sets were reconstructed\\u000a in 5% steps from 30% to 80% of the R-R interval. Two blinded

Gorka Bastarrika; Carlo N. De Cecco; Maria Arraiza; Matias Ubilla; Stefano Mastrobuoni; Jesús C. Pueyo; Gregorio Rábago

2008-01-01

38

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

39

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

40

Augmented reality image guidance for minimally invasive coronary artery bypass  

NASA Astrophysics Data System (ADS)

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

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

2008-03-01

41

Automatic determination of the artery vein ratio in retinal images  

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

42

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

43

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. PMID:24420443

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

2014-01-01

44

Quantitation Of Coronary Artery Dimensions Using Digital Image Processing  

NASA Astrophysics Data System (ADS)

Sequential observations of coronary artery disease depend upon reproducibility of measurements of coronary dimensions. Because the coronary artery segment to be digitized for quantitation occupies only a small portion of the 35 mm cine frame, a cine projector was mounted on a movable X, Y stage so that the area of interest could be focused through a lens turret system onto a video camera. The lens turret provides lx, 3.5x, and 7x magnification. A digital image processing device operating under computer control permits direct application of smoothing and edge finding algorithms to the magnified coronary image. Using separately recorded grids, an external reference marker, and isocentering of the heart within a U-arm radiographic system, it is possible to adjust for distortion and magnification. A split screen technique provides capability for single plane or sequential biplane analyses. A digital lightpen is used to input fiducial points for segment identification and define an initial coronary margin which is superceded by computer defined edges. Final measurements include maximum, minimum and mean diameter of 1.0 cm long coronary segments and the absolute area of the segment profile, along with provision for hard copy image recording. Reproducibility of the minimum and maximum diameter measurements provided by the digitization system and edge finding algorithm are + .06 mm for vessels with an average diameter of 2.3 mm (+ S.D.). When duplicate coronary injections during the same catheterization procedure are made, the coefficient of variation of the minimum diameter is 9.5%, of the maximum diameter 5.0% and of the segment area 3.9%. The capability for area of interest selectivity, variable optical magnification and digital image analysis provides a unique and reproducible system for coronary segment quantitation.

Alderman, Edwin L.; Berte, Larry E.; Harrison, Donald C.; Sanders, William

1981-11-01

45

Seven challenges for image quality research  

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

46

New quality measures for image fusion  

Microsoft Academic Search

We present a new approach for assessing quality in image fusion. The interest of our measures lies in the fact that they do not require a ground-truth or reference image and can be easily computed. We perform simulations which show that our measures are compliant with subjective evaluations and can therefore be used to compare different image fusion methods or

Gemma Piella

2004-01-01

47

Does resolution really increase image quality?  

Microsoft Academic Search

A general trend in the CMOS image sensor market is for increasing resolution (by having a larger number of pixels) while keeping a small form factor by shrinking photosite size. This article discusses the impact of this trend on some of the main attributes of image quality. The first example is image sharpness. A smaller pitch theoretically allows a larger

Christel-Loïc Tisse; Frédéric Guichard; Frédéric Cao

2008-01-01

48

Rapid and complete coronary arterial tree visualization with magnetic resonance imaging: feasibility and diagnostic performance  

Microsoft Academic Search

Aims Current imaging of the coronary arteries with magnetic resonance coronary angiography (MRCA) is restricted to limited coverage of the coronary arterial tree and requires complex planning. We present and evaluate a rapid, single-scan MRCA approach with complete coverage of the coronary arterial tree. Methods and results Fifty-five consecutive patients with suspected coronary artery disease underwent free-breathing, navigator-gated MRCA using

Cosima Jahnke; Ingo Paetsch; Kay Nehrke; Bernhard Schnackenburg; Rolf Gebker; Eckart Fleck; Eike Nagel

2005-01-01

49

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

50

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

51

Patient satisfaction and disease specific quality of life after uterine artery embolization  

Microsoft Academic Search

ObjectivesThis study was undertaken to evaluate changes in fibroid specific symptom severity and health-related quality of life (HRQOL) after uterine artery embolization (UAE) and to consider the impact of these changes on satisfaction with the procedure.

Wendy J Smith; Elizabeth Upton; Elizabeth J Shuster; Arnold J Klein; Martin L Schwartz

2004-01-01

52

Quality of Life in Women with Coronary Artery Disease  

PubMed Central

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

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

2014-01-01

53

Non-invasive imaging for subclinical coronary atherosclerosis in patients with peripheral artery disease.  

PubMed

Patients with peripheral artery disease are at high risk of coronary artery disease. An increasing number of studies show that a large proportion of patients with peripheral artery disease have significant coronary atherosclerosis, even in the absence of symptoms. Although the reported prevalence of subclinical coronary artery disease varies widely in patients with peripheral artery disease, it could include more than half of patients. No consensus exists to date on either the rationale for screening patients with peripheral artery disease for coronary atherosclerosis or the optimal algorithm and method for screening. An increasing number of imaging modalities are emerging that allow improved in vivo non-invasive characterization of atherosclerotic plaques. These novel imaging methods may lead to early detection of high-risk vulnerable plaques, enabling clinicians to improve risk stratification of patients with peripheral artery disease, and thus paving the way for individualized therapy. PMID:24691587

Ripa, Rasmus Sejersten; Kjaer, Andreas; Hesse, Birger

2014-06-01

54

Image quality and wafer level optics  

NASA Astrophysics Data System (ADS)

Increasing demand from consumers to integrate camera modules into electronic devices, such as cell phones, has driven the cost of camera modules down very rapidly. Now that most cell phones include at least one camera, consumers are starting to ask for better image quality - without compromising on the cost. Wafer level optics has emerged over the past few years as an innovative technology enabling simultaneous manufacturing of thousands of lenses, at the wafer level. Using reflow-compatible materials to manufacture these lenses permits a reduction in the cost and size of camera module, thus answering the market demand for lowering the cost. But what about image quality? The author will present image quality analysis that was conducted for both VGA and megapixel camera resolutions. Comparison between conventional camera modules and wafer level camera modules shows wafer level technology brings equivalent, if not better, image quality performance compared to conventional camera modules.

Dagan, Y.; Humpston, G.

2010-05-01

55

Steganalysis using image quality metrics  

Microsoft Academic Search

Abstract: We present techniques for steganalysis of images thathave been potentially subjected to steganographic algorithms, bothwithin the passive warden and active warden frameworks. Our hypothesisis that steganographic schemes leave statistical evidencethat can be exploited for detection with the aid of image qualityfeatures and multivariate regression analysis. To this effect imagequality metrics have been identified based on the analysis of variance(ANOVA)

Ismail Avcibas; Nasir D. Memon; Bülent Sankur

2003-01-01

56

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. PMID:24285942

Piccinelli, Marina; Garcia, Ernest

2013-01-01

57

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

58

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

59

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.

60

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

61

Evaluating the visual quality of watermarked images  

NASA Astrophysics Data System (ADS)

A recent image quality measure, M-SVD, can express the quality of distorted images either numerically or graphically. Based on the Singular Value Decomposition (SVD), it consistently measures the distortion across different distortion types and within a given distortion type at different distortion levels. The SVD decomposes every real matrix into a product of three matrices A = USV T, where U and V are orthogonal matrices, U TU = I, V TV = I and S = diag (s I, s II, ...). The diagonal entries of S are called the singular values of A, the columns of U are called the left singular vectors of A, and the columns of V are called the right singular vectors of A. M-SVD, as a graphical measure, computes the distance between the singular values of the original image block and the singular values of the distorted image block, where n x n is the block size. If the image size is k x k, we have (k/n) x (k/n) blocks. The set of distances, when displayed in a graph, represents a "distortion map." The numerical measure is derived from the graphical measure. It computes the global error expressed as a single numerical value. In this paper, we will extend the SVD-based image quality measure to evaluate the visual quality of watermarked images using several watermarking schemes.

Shnayderman, Aleksandr; Eskicioglu, Ahmet M.

2006-02-01

62

Color image attribute and quality measurements  

NASA Astrophysics Data System (ADS)

Color image quality measures have been used for many computer vision tasks. In practical applications, the no-reference (NR) measures are desirable because reference images are not always accessible. However, only limited success has been achieved. Most existing NR quality assessments require that the types of image distortion is known a-priori. In this paper, three NR color image attributes: colorfulness, sharpness and contrast are quantified by new metrics. Using these metrics, a new Color Quality Measure (CQM), which is based on the linear combination of these three color image attributes, is presented. We evaluated the performance of several state-of-the-art no-reference measures for comparison purposes. Experimental results demonstrate the CQM correlates well with evaluations obtained from human observers and it operates in real time. The results also show that the presented CQM outperforms previous works with respect to ranking image quality among images containing the same or different contents. Finally, the performance of CQM is independent of distortion types, which is demonstrated in the experimental results.

Gao, Chen; Panetta, Karen; Agaian, Sos

2014-05-01

63

Combined magnetic resonance coronary artery imaging, myocardial perfusion and late gadolinium enhancement in patients with suspected coronary artery disease  

Microsoft Academic Search

BACKGROUND: Cardiovascular Magnetic Resonance (CMR) imaging offers methods for the detection of ischemia and myocardial infarction as well as visualization of the coronary arteries (MRCA). However, a direct comparison of adenosine perfusion (PERF), late gadolinium enhancement (LGE) and MRCA or the results of their combination has not been performed. Aim of the study was to evaluate the feasibility\\/diagnostic performance of

Christoph Klein; Rolf Gebker; Thomas Kokocinski; Stephan Dreysse; Bernhard Schnackenburg; Eckart Fleck; Eike Nagel

2008-01-01

64

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.

2008-03-01

65

Contrast imaging and gene delivery through the combined use of novel cationic liposomal microbubbles and ultrasound in rat carotid arteries  

PubMed Central

Introduction Lipid-coated cationic microbubbles represent a new class of agents with both diagnostic and therapeutic applications. The main goal of this study was to evaluate the efficiency of gene transfer through the combined use of microbubbles and ultrasound in rat carotid arteries. Furthermore, we assessed whether the cationic liposomal microbubbles could allow long-term enhanced imaging, comparing with SonoVue®. Material and methods Normal rat carotid arteries were imaged after intravenous bolus injections of 0.5 ml/kg of two contrast agents (SonoVue® and the cationic liposomal microbubbles). Forty Sprague-Dawley rats were divided into 5 groups according to ultrasound parameters and were treated with or without microbubbles. All rats were sacrificed after being transfected for 2 days. The level of protein expression was determined by western blot analysis. Results The enhancing time of self-made microbubbles was much longer than that of SonoVue® in rat carotid arteries (p < 0.05). The results of the western blot analysis revealed that the expression of SR-BI DNA in the carotid artery was highest in the SR-BI + US/CLM group (p < 0.05). Conclusions These results suggest that the novel cationic liposomal microbubbles enhance image quality over a longer period than does SonoVue®. Additionally, the combination of ultrasound and this new type of microbubble can act synergistically to increase SR-BI DNA transfection. PMID:23671448

Liu, Fang; Huang, Yunxia; Guo, Wei; Rui, Mengjie; Xu, Yuhong; Hu, Bing

2013-01-01

66

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

67

Magnetic resonance imaging planes for the 3-dimensional characterisation of human coronary arteries.  

PubMed Central

We report a magnetic resonance imaging study which developed a consistent hierarchy of imaging planes for examination of the origins, courses and principal branches of the main coronary arteries of prepared human cadaveric hearts. The reference longitudinal axis was chosen between the aortic valve and the apex of the left ventricle. A series of transverse planes then successfully visualised the ostia of the left and right coronary arteries; the left main coronary, its bifurcation, and the left anterior descending artery for a distance 24 mm distal to its origin were clearly distinct in successively posterior sections as was the emergence and course of the right coronary artery. Further sections were derived from an axis that joined the posterior aspects of the left and right coronary artery ostia seen in cross-section, which demonstrated the origins of these arteries. They also traced the circumflex artery 30 mm beyond its point of emergence and demonstrated the course of the right coronary artery between the right ventricle and right atrium. The anatomical identifications were confirmed in selective 3-dimensional reconstructions of the cardiac anatomy around the aortic root and pulmonary artery origin. The orthogonal anatomical arrangements of the left and right coronary artery arterial trees thus permit a consistent set of imaging planes useful for the visualisation of all the major branches in a static heart in vitro. This may offer an approach useful for clinical imaging of human coronary vessels in vivo in the moving heart. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Fig. 9 PMID:7961140

Gates, A R; Huang, C L; Crowley, J J; Gresham, A; Shapiro, L M; Carpenter, T A; Hall, L D

1994-01-01

68

Quality Improvement Guidelines for Uterine Artery Embolization for Symptomatic Leiomyomata  

Microsoft Academic Search

Uterine artery embolization (UAE) is assuming an important role in the treatment of women with symptomatic uterine leiomyomata worldwide. The following guidelines, which have been jointly published with the Society of Interventional Radiology in the Journal of Vascular and Interventional Radiology, are intended to ensure the safe practice of UAE by identifying the elements of appropriate patient selection, anticipated outcomes,

David M. Hovsepian; Gary P. Siskin; Joseph Bonn; John F. Cardella; Timothy W. I. Clark; Leo E. Lampmann; Donald L. Miller; Reed A. Omary; Jean-Pierre Pelage; Dheeraj Rajan; Marc S. Schwartzberg; Richard B. Towbin; Woodruff J. Walker; David Sacks

2004-01-01

69

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

70

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

NASA Astrophysics Data System (ADS)

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

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

2000-05-01

71

Balancing Image Quality and Energy Consumption in Visual Sensor Networks  

E-print Network

Balancing Image Quality and Energy Consumption in Visual Sensor Networks Kit-Yee Chow, King studies the tradeoff between image quality and energy consumption. We study the scenario that a number in image quality. The tradeoff between image quality and energy consumption of different routing presents

Tam, Vincent W. L.

72

Incorporating Image Quality in Multi-algorithm Fingerprint Verification  

E-print Network

to enhanced performance over a wide range of fingerprint image quality. 1 Introduction The increasing need first objective in this work is to investigate the effects of varying image quality [3 of fingerprint image quality, and describe the fingerprint image quality measure used in this work. In Sect. 3 we

Autonoma de Madrid, Universidad

73

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

SciTech Connect

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

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

1981-08-01

74

Gadolinium-Enhanced MR Imaging in the Evaluation of Uterine Fibroids Treated with Uterine Artery Embolization  

Microsoft Academic Search

OBJECTIVE . The purpose of this study was to determine whether tumor volume reduc- tion can be predicted by the infarction rate of uterine fibroids as seen on gadolinium-enhanced MR images obtained immediately after uterine artery embolization. MATERIALS AND METHODS . In our study, 36 women with symptomatic uterine fi- broids successfully underwent uterine artery embolization. Unenhanced and enhanced MR

Tetsuya Katsumori; Kazuhiro Nakajima; Mitsukuni Tokuhiro

75

Carotid Artery Disease Assessed by Color Doppler Flow Imaging: Correlation with Standard Doppler Sonography and Angiography  

Microsoft Academic Search

Carotid artery disease was assessed in 180 patients by means of color Doppler flow imaging. Color Doppler findings in 360 carotid arteries were compared with the results of standard Doppler sonography, and color Doppler findings in 60 bifurcations were compared with the results of intraarterial angiography. The sensitivity of color Doppler for the detection of carotid disease was 100% when

Wolfgang Steinke

76

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

E-print Network

limitations of existing methods, which in general depend on accurate edge detection of the arterial wall on detection of the arterial wall edge have been proposed in the literature over the last ten years. The first the maximum image gradient, where the vessel wall is assumed to be located7-10 . The last efforts are centered

Frangi, Alejandro

77

Power Doppler imaging and color Doppler flow imaging for the evaluation of normal and pathological vertebral arteries.  

PubMed

Recently, an ultrasound method for vascular applications using the amplitude of the reflected echosignal for the generation of intravascular color signals has been introduced. We compared the utility of this power Doppler imaging (PDI) with conventional color Doppler flow imaging (CDFI) for examination of vertebral arteries (VA). Forty-nine patients with signs and symptoms suggesting ischemia within the posterior circulation were evaluated. Quality of blood flow visualization by PDI and CDFI at the different VA segments was classified according to a four point scale. Furthermore, combined sonographic findings were correlated with the results of digital substraction and/or magnetic resonance angiography (DSA, MRA). Power Doppler imaging provided a significantly superior visualization of the intertransversal VA, whereas display of the intracranial V4 segment was superior significantly on CDFI. Both methods were complementary for the evaluation of the VA at the origin. With respect to the angiographic findings, combined CDFI and PDI achieved a sensitivity of 90.63% and a specificity of 97.22% for the differentiation of healthy and pathologic VAs. Power Doppler imaging is complementary to CDFI for the sonographic assessment of VA disease. Combined use of PDI and CDFI achieves a high sensitivity and specificity, thus increasing diagnostic confidence. PMID:9557142

Ries, S; Steinke, W; Devuyst, G; Artemis, N; Valikovics, A; Hennerici, M

1998-04-01

78

Magnetic resonance imaging of suspected cervicocranial arterial dissections.  

PubMed

The authors propose that the optimal screening protocol for evaluation of suspected cervicocranial arterial dissections is magnetic resonance imaging (MRI) that includes three components: 1) contrast-enhanced three-dimensional time-of-flight magnetic resonance angiography (MRA) through the superior mediastinum, neck, and skull base; 2) three-dimensional multiple overlapping thin-section acquisition MRA of the skull base and Circle of Willis region; and 3) axial non-contrast, non-fat-suppressed T1-weighted, fat-suppressed T1-weighted, and T2-weighted spin-echo MRI from the level of the aortic arch through the level of the circle of Willis. MRA permits visualization of vascular luminal narrowing or obliteration, which can suggest vascular dissection but can also be caused by congenital variation, dysplasia, intraluminal thrombus, vasospasm, or extramural compression by tumor. By directly visualizing the blood vessel wall, axial T1-weighted and T2-weighted spin-echo MRI can identify the intramural hemorrhage of vascular dissection. This protocol is designed to maximize the sensitivity of a noninvasive technique and may eliminate the need for conventional endovascular angiography. PMID:15662248

Shah, Gaurang V; Quint, Douglas J; Trobe, Jonathan D

2004-12-01

79

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. PMID:23097307

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

80

Retinal image quality, reading and myopia  

Microsoft Academic Search

Analysis was undertaken of the retinal image characteristics of the best-spectacle corrected eyes of progressing myopes (n=20, mean age=22years; mean spherical equivalent=?3.84D) and a control group of emmetropes (n=20, mean age=23years; mean spherical equivalent=0.00D) before and after a 2h reading task. Retinal image quality was calculated based upon wavefront measurements taken with a Hartmann–Shack sensor with fixation on both a

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

2006-01-01

81

Subjective evaluation of compressed image quality  

NASA Astrophysics Data System (ADS)

Lossy data compression generates distortion or error on the reconstructed image and the distortion becomes visible as the compression ratio increases. Even at the same compression ratio, the distortion appears differently depending on the compression method used. Because of the nonlinearity of the human visual system and lossy data compression methods, we have evaluated subjectively the quality of medical images compressed with two different methods, an intraframe and interframe coding algorithms. The evaluated raw data were analyzed statistically to measure interrater reliability and reliability of an individual reader. Also, the analysis of variance was used to identify which compression method is better statistically, and from what compression ratio the quality of a compressed image is evaluated as poorer than that of the original. Nine x-ray CT head images from three patients were used as test cases. Six radiologists participated in reading the 99 images (some were duplicates) compressed at four different compression ratios, original, 5:1, 10:1, and 15:1. The six readers agree more than by chance alone and their agreement was statistically significant, but there were large variations among readers as well as within a reader. The displacement estimated interframe coding algorithm is significantly better in quality than that of the 2-D block DCT at significance level 0.05. Also, 10:1 compressed images with the interframe coding algorithm do not show any significant differences from the original at level 0.05.

Lee, Heesub; Rowberg, Alan H.; Frank, Mark S.; Choi, Hyung-Sik; Kim, Yongmin

1992-05-01

82

Quality Improvement Guidelines for Uterine Artery Embolization for Symptomatic Leiomyomata  

SciTech Connect

Uterine artery embolization (UAE) is assuming an important role in the treatment of women with symptomatic uterine leiomyomata worldwide. The following guidelines, which have been jointly published with the Society of Interventional Radiology in the Journal of Vascular and Interventional Radiology, are intended to ensure the safe practice of UAE by identifying the elements of appropriate patient selection, anticipated outcomes, and recognition of possible complications and their timely address.

Hovsepian, David M. [Mallinckrodt Institute of Radiology, Division of Vascular and Interventional Radiology (United States)], E-mail: hovsepiand@mir.wustl.edu; Siskin, Gary P. [Albany Medical College, Department of Vascular Radiology (United States); Bonn, Joseph [Thomas Jefferson University Hospital, Department of Radiology (United States)] (and others)

2004-08-15

83

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. PMID:24959497

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

2014-01-01

84

Subjective matters: from image quality to image psychology  

NASA Astrophysics Data System (ADS)

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

Fedorovskaya, Elena A.; De Ridder, Huib

2013-03-01

85

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

2010-04-01

86

Measuring image quality in overlapping areas of panoramic composed images  

NASA Astrophysics Data System (ADS)

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

Mitjà, Carles; Bover, Toni; Escofet, Jaume

2012-06-01

87

[Usefulness of virtual vessel images in ppi for treatment of complete obstruction of leg arteries].  

PubMed

Following recent rapid advances in devices and treatment technology, indications for percutaneous peripheral intervention (PPI) have been expanded to include complex lesions (long-segment lesions, completely obstructed chronic lesions, etc.) and even lesions of the superficial femoral artery and arteries distal to the popliteal artery. However, when PPI is used for treatment of complete obstruction, treatment can take a long time or its outcome can be less satisfactory for reasons such as difficulty in assessing the vascular distribution/arrangement or the direction of calcification in the obstructed area or excessively long lesions. In the present study, we conducted three-dimensional image processing of CT data from leg arteries conventionally used for preoperative diagnosis. Using this processing technique, we created virtual images of the blood vessels of the completely obstructed area and mapped these virtual vessel images onto the fluoroscopic monitor image during catheter treatment. The usefulness of this technique for PPI was then evaluated. We succeeded in creating virtual vessel images of the completely obstructed parts of leg arteries with the use of preoperative CT images of leg arteries that we then mapped onto the fluoroscopic monitor images during treatment. We were successful in mapping virtual images onto the abdominal aorta in 96.8% of cases and in 95.7% with the common iliac artery. This technique is thus able to supply reliable information on vascular distribution/arrangement, suggesting that it can enable the surgeon to advance the treatment device precisely along the vessels, making it useful for treatment with PPI. The study additionally showed that differences in the angle of imaging affect the manual mapping of the CT images onto angiograms. PMID:25327424

Kittaka, Daisuke; Sato, Hisaya; Nakai, Yuichi; Kato, Kyoichi; Nakazawa, Yasuo

2014-10-01

88

Fingerprint quality assurance using image processing  

E-print Network

Fingerprint quality assurance using image processing Marek Dusio Kongens Lyngby 2013 IMM-M.Sc.-2013 analysis methods that are fast to compute. Of interest are analysing the impact of ngertip skin moisture Modelling at the Technical University of Denmark during an exchange visit at the Center for Advanced

89

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

90

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

91

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

92

Quality evaluation for compressed medical images: Diagnostic Accuracy  

Microsoft Academic Search

We examined in the previous chapter several common computable measures of image quality, as well as subjective quality ratings. While these quality measures are useful in many ways, for medical images one wishes a quality measure to take proper account of the diagnostic purpose of the image. The ROC methodology discussed in the previous chapter is one approach to this.

Pamela Cosman; Robert Gray; Richard Olshen

93

Application-driven Spectral Image Quality Assessment and Prediction  

E-print Network

image quality metric is discussed with an approach proposed. Quality is divided into fidelity. ©2010 Optical Society of America OCIS codes: (110.3000) Image quality assessment; (110 of the Earth [4]. In this context, spectral imaging includes both multispectral imaging systems

Kerekes, John

94

Quantitative Statistical Methods for Image Quality Assessment  

PubMed Central

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

Dutta, Joyita; Ahn, Sangtae; Li, Quanzheng

2013-01-01

95

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. PMID:23612440

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

2013-01-01

96

Multiresolution Approach for Noncontact Measurements of Arterial Pulse Using Thermal Imaging  

NASA Astrophysics Data System (ADS)

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

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

97

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

98

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

PubMed Central

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

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

2014-01-01

99

Dried fruits quality assessment by hyperspectral imaging  

NASA Astrophysics Data System (ADS)

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

Serranti, Silvia; Gargiulo, Aldo; Bonifazi, Giuseppe

2012-05-01

100

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

101

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

Microsoft Academic Search

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

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

2004-01-01

102

Effect of physical activity on the life quality of coronary artery bypass graft patients  

PubMed Central

Abstract Introduction. The quality of life depends on physical, psychological and social factors that are evidently influenced by the individual’s actions, prospect, attitude and behavior. Heart disease is one of the most imperative health problems in the world. Studies showed that exercise-based rehabilitation for patients with coronary artery disease effectively lowers the rate of cardiac death. The intent of this study was to determine the effects of physical activity on the life quality of cardiovascular patients after coronary artery bypass graft. Materials and Methods. This randomized clinical trial was performed on two groups of coronary artery patients of Yazd Afshar hospital. All the 70 participants were post surgery coronary artery patients who were divided into two groups. Data was collected by two questionnaires: A personal information questionnaire and a quality of life questionnaire (SF=36). Data of both groups was collected in the first and fourth month after the discharge from surgery and sessions were analyzed by SPSS 16 and by using T-test and Chi-square. Results. Results displayed that after the intervention, all the categories of the components of the quality of life were increased except for general health. There was no significant differentiation between these statuses in the control group and the premier grades about the components of the social function (88.98 out of 100). The comparison of total scores of the quality of life before the intervention showed the quality of life of both groups one month after surgery was not significant (p=75%), but in four months after surgery, the distinction between the mean grade scores of the intervention, the group was considerable (p=0.0001). Conclusion. The comparison of the total scores of the quality of life indicated an increase in the scores of the quality of life in the intervention group after the exercise.

Firouzabadi, MG; Sherafat, A; Vafaeenasab, M

2014-01-01

103

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. PMID:22426319

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

104

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

105

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

SciTech Connect

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

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

1983-01-01

106

Evolution of unilateral perinatal arterial ischemic stroke on conventional and diffusion-weighted MR imaging  

Microsoft Academic Search

BACKGROUND AND PURPOSE: Knowledge of the sequence of signal-intensity (SI) changes on conventional and diffusion-weighted MR imaging (DWI) following perinatal arterial ischemic stroke (PAIS) is limited, adding to the difficulty in timing the onset of PAIS. We hypothesized that SI changes seen on early sequential MR imaging following PAIS should follow a similar time course. The aim of this study

J. Dudink; E. Mercuri; L. Al-Nakib; P. Govaert; S. J. Counsell; M. A. Rutherford; F. M. Cowan

2009-01-01

107

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

E-print Network

measure- ments. Another limitation is that only the dominant heart rate frequency is reported electrically. Doppler ultrasound and arterial tonometry are traditional approaches to track the hemodynamics of heart rate from the superficial blood vessel network. In their ap- proach, they estimate the dominant

Farag, Aly A.

108

Totally blind image quality assessment evaluator  

NASA Astrophysics Data System (ADS)

Most general purpose no-reference image quality assessment algorithms need prior knowledge about anticipated distortions and their corresponding human opinion scores. One or more of distortion types may not be available when creating the model. In this paper, we develop a blind/no-reference opinion unaware distortion unaware image quality assessment algorithm based on natural scenes. The proposed approach extracts features in spatial domain for both natural images and distorted image at two scales, where locally normalized luminance values are modeled in two forms: pointwise for single pixels and pair-wise based log-derivative for the relationship of adjacent pixels. Then two sharpness functions are applied whose their outputs represent the extracted features of the proposed approach. Results show that the proposed algorithm correlates well with subjective opinion scores. They also show that the proposed algorithm outperforms the full-reference PSNR and SSIM methods. Not only do the results compete well with the recently developed NIQE model, but also outperform it.

Abdalmajeed, Saifeldeen; Shuhong, Jiao; Wei, Liu

2014-01-01

109

Improving secondary ion mass spectrometry image quality with image fusion.  

PubMed

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. PMID:24912432

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

2014-12-01

110

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

111

Safety of Intravenous Fibrinolysis in Imaging-Confirmed Single Penetrator Artery Infarcts  

PubMed Central

Background Hemorrhagic transformation (HT) after fibrinolytic therapy may be less common in patients with acute cerebral ischemia confined to single penetrator artery (SPA) territories than in patients with large artery ischemia. However, prior investigations of HT diagnosed small vessel ischemia based on lacunar clinical syndromes, an approach known to yield misdiagnosis in one-third to one-half of cases. Methods Consecutive intravenous t-PA treated patients in a prospectively maintained hospital registry were analyzed. Patients were classified as having SPA ischemia if they had imaging evidence of: 1) deep location, 2) diameter ?1.5 cm, and 3) distribution in a single penetrator territory, regardless of presenting clinical syndrome. Lacunar clinical syndrome was defined according to the Oxfordshire Community Stroke Project classification. Results Among 93 intravenous t-PA-treated patients, mean age was 71.5, 62.4% were female, and median pretreatment NIHSS score was 14. Single penetrator artery ischemia was imaged in 13 (14.0%) and large artery ischemia in 75 (80.6%), with no visualized ischemic injury in 5 (5.4%). Lacunar clinical syndromes were present in 23 (24.7%), including 10 with SPA ischemia and 9 with large artery ischemia. No patient with imaging-confirmed SPA infarcts experienced any hemorrhagic transformation, while any radiologic HT occurred in 29.3% of large artery infarcts, p = 0.03. Symptomatic ICH occurred in 0% of SPA infarcts vs. 4.0% of large artery infarcts. Conclusion HT after lytic therapy in imaging-confirmed SPA infarcts is uncommon. Imaging demonstration of ischemia confined to a SPA territory better identifies this population at low risk of hemorrhagic complications than clinical lacunar syndromes. PMID:20947857

Lee, Soo Joo; Saver, Jeffrey L.; Liebeskind, David S.; Ali, Latisha; Ovbiagele, Bruce; Kim, Doojin; Vespa, Paul; Froehler, Michael; Tenser, Matthew; Gadhia, Jignesh; Starkman, Sidney

2011-01-01

112

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

113

Reconstruction algorithm for improved ultrasound image quality  

PubMed Central

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

Madore, Bruno; Meral, F. Can

2012-01-01

114

Wavelet-based image fusion and quality assessment  

NASA Astrophysics Data System (ADS)

Recent developments in satellite and sensor technologies have provided high-resolution satellite images. Image fusion techniques can improve the quality, and increase the application of these data. This paper addresses two issues in image fusion (a) the image fusion method and (b) corresponding quality assessment. Firstly, a multi-band wavelet-based image fusion method is presented, which is a further development of the two-band wavelet transformation. This fusion method is then applied to a case study to demonstrate its performance in image fusion. Secondly, quality assessment for fused images is discussed. The objectives of image fusion include enhancing the visibility of the image and improving the spatial resolution and the spectral information of the original images. For assessing quality of an image after fusion, we define the aspects to be assessed initially. These include, for instance, spatial and spectral resolution, quantity of information, visibility, contrast, or details of features of interest. Quality assessment is application dependant; different applications may require different aspects of image quality. Based on this analysis, a set of qualities is classified and analyzed. These sets of qualities include (a) average grey value, for representing intensity of an image, (b) standard deviation, information entropy, profile intensity curve for assessing details of fused images, and (c) bias and correlation coefficient for measuring distortion between the original image and fused image in terms of spectral information.

Shi, Wenzhong; Zhu, ChangQing; Tian, Yan; Nichol, Janet

2005-03-01

115

RIS-M-2314 QUALITY OF THE RADIOGRAPHIC IMAGE IN  

E-print Network

RISÃ?-M-2314 QUALITY OF THE RADIOGRAPHIC IMAGE IN PAPER RADIOGRAPHY J.C. Domanus and H.M. El Fouly Abstract. The quality of the radiographic image was investigated by the use of standard ISO wire Image are reproduced in this report. * INIS-descriptors; COMPARITIVE EVALUATIONS? IMAGES; INDUSTRIAL RADIOGRAPHY

116

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

Microsoft Academic Search

The practical aspects of the dosimetric and imaging performance of a digital x-ray system for cardiology procedures were evaluated. The system was configured with an image intensifier (II) and later upgraded to a dynamic flat panel detector (FD). Entrance surface air kerma (ESAK) to phantoms of 16, 20, 24 and 28 cm of polymethyl methacrylate (PMMA) and the image quality

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

2005-01-01

117

Scan Techniques for Cardiac and Coronary Artery Imaging With Multislice CT  

Microsoft Academic Search

Cardiac imaging is a demanding application for any noninvasive imaging modality. On the one hand, high temporal resolution\\u000a is needed to virtually freeze cardiac motion and thus avoid motion artifacts in the images. On the other hand, sufficient\\u000a spatial resolution—at best submillimeter—is required to adequately visualize small and complex anatomical structures like\\u000a the coronary arteries. The complete heart volume has

Bernd M. Ohnesorge; Brian R. Westerman; U. Joseph Schoepf

118

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

119

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

120

Lower use of carotid artery imaging at minority-serving hospitals  

PubMed Central

Objective: We determined whether site of care explains a previously identified racial disparity in carotid artery imaging. Methods: In this retrospective cohort study, data were obtained from a chart review of veterans hospitalized with ischemic stroke at 127 Veterans Administration hospitals in 2007. Extensive exclusion criteria were applied to obtain a sample who should have received carotid artery imaging. Minority-serving hospitals were defined as the top 10% of hospitals ranked by the proportion of stroke patients who were black. Population level multivariate logistic regression models with adjustment for correlation of patients in hospitals were used to calculate predictive probabilities of carotid artery imaging by race and minority-service hospital status. Bootstrapping was used to obtain 95% confidence intervals (CIs). Results: The sample consisted of 1,534 white patients and 628 black patients. Nearly 40% of all black patients were admitted to 1 of 13 minority-serving hospitals. No racial disparity in receipt of carotid artery imaging was detected within nonminority serving hospitals. However, the predicted probability of receiving carotid artery imaging for white patients at nonminority-serving hospitals (89.7%, 95% CI [87.3%, 92.1%]) was significantly higher than both white patients (78.0% [68.3%, 87.8%] and black patients (70.5% [59.3%, 81.6%]) at minority-serving hospitals. Conclusions: Underuse of carotid artery imaging occurred most often among patients hospitalized at minority-serving hospitals. Further work is required to explore why site of care is a mechanism for racial disparities in this clinically important diagnostic test. PMID:22700815

Keyhani, Salomeh; Ofner, Susan; Williams, Linda S.; Hebert, Paul L.; Ordin, Diana L.; Bravata, Dawn M.

2012-01-01

121

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

122

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

123

Visualization of coronary arteries in patients after childhood Kawasaki syndrome: value of multidetector CT and MR imaging in comparison to conventional coronary catheterization  

Microsoft Academic Search

Background  After childhood Kawasaki syndrome (KS) the coronary arteries undergo a lifelong dynamic pathological change, and follow-up\\u000a coronary artery imaging is essential. At present, conventional coronary catheterization (CCC) and angiography is still regarded\\u000a as the gold standard. Less-invasive methods such as multidetector CT angiography (MDCT-A) and MRI have been used sporadically.\\u000a \\u000a \\u000a \\u000a Objective  To compare the diagnostic quality of MDCT-A and MRI with

Raoul Arnold; Sebastian Ley; Julia Ley-Zaporozhan; Joachim Eichhorn; Jens-Peter Schenk; Herbert Ulmer; Hans-Ulrich Kauczor

2007-01-01

124

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

SciTech Connect

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

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

2010-04-15

125

Molecular imaging of plaques in coronary arteries with PET and SPECT  

PubMed Central

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

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

2014-01-01

126

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

PubMed

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

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

2014-09-01

127

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

128

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

PubMed Central

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

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

2011-01-01

129

Image reconstruction and image quality evaluation for a dual source CT scanner.  

PubMed

The authors present and evaluate concepts for image reconstruction in dual source CT (DSCT). They describe both standard spiral (helical) DSCT image reconstruction and electrocardiogram (ECG)-synchronized image reconstruction. For a compact mechanical design of the DSCT, one detector (A) can cover the full scan field of view, while the other detector (B) has to be restricted to a smaller, central field of view. The authors develop an algorithm for scan data completion, extrapolating truncated data of detector (B) by using data of detector (A). They propose a unified framework for convolution and simultaneous 3D backprojection of both (A) and (B) data, with similar treatment of standard spiral, ECG-gated spiral, and sequential (axial) scan data. In ECG-synchronized image reconstruction, a flexible scan data range per measurement system can be used to trade off temporal resolution for reduced image noise. Both data extrapolation and image reconstruction are evaluated by means of computer simulated data of anthropomorphic phantoms, by phantom measurements and patient studies. The authors show that a consistent filter direction along the spiral tangent on both detectors is essential to reduce cone-beam artifacts, requiring truncation of the extrapolated (B) data after convolution in standard spiral scans. Reconstructions of an anthropomorphic thorax phantom demonstrate good image quality and dose accumulation as theoretically expected for simultaneous 3D backprojection of the filtered (A) data and the truncated filtered (B) data into the same 3D image volume. In ECG-gated spiral modes, spiral slice sensitivity profiles (SSPs) show only minor dependence on the patient's heart rate if the spiral pitch is properly adapted. Measurements with a thin gold plate phantom result in effective slice widths (full width at half maximum of the SSP) of 0.63-0.69 mm for the nominal 0.6 mm slice and 0.82-0.87 mm for the nominal 0.75 mm slice. The visually determined through-plane (z axis) spatial resolution in a bar pattern phantom is 0.33-0.36 mm for the nominal 0.6 mm slice and 0.45 mm for the nominal 0.75 mm slice, again almost independent of the patient's heart rate. The authors verify the theoretically expected temporal resolution of 83 ms at 330 ms gantry rotation time by blur free images of a moving coronary artery phantom with 90 ms rest phase and demonstrate image noise reduction as predicted for increased reconstruction data ranges per measurement system. Finally, they show that the smoothness of the transition between image stacks acquired in different cardiac cycles can be efficiently controlled with the proposed approach for ECG-synchronized image reconstruction. PMID:19175144

Flohr, T G; Bruder, H; Stierstorfer, K; Petersilka, M; Schmidt, B; McCollough, C H

2008-12-01

130

Cardiac Magnetic Resonance Imaging for the Diagnosis of Coronary Artery Disease  

PubMed Central

Executive Summary In July 2009, the Medical Advisory Secretariat (MAS) began work on Non-Invasive Cardiac Imaging Technologies for the Diagnosis of Coronary Artery Disease (CAD), an evidence-based review of the literature surrounding different cardiac imaging modalities to ensure that appropriate technologies are accessed by patients suspected of having CAD. This project came about when the Health Services Branch at the Ministry of Health and Long-Term Care asked MAS to provide an evidentiary platform on effectiveness and cost-effectiveness of non-invasive cardiac imaging modalities. After an initial review of the strategy and consultation with experts, MAS identified five key non-invasive cardiac imaging technologies for the diagnosis of CAD. Evidence-based analyses have been prepared for each of these five imaging modalities: cardiac magnetic resonance imaging, single photon emission computed tomography, 64-slice computed tomographic angiography, stress echocardiography, and stress echocardiography with contrast. For each technology, an economic analysis was also completed (where appropriate). A summary decision analytic model was then developed to encapsulate the data from each of these reports (available on the OHTAC and MAS website). The Non-Invasive Cardiac Imaging Technologies for the Diagnosis of Coronary Artery Disease series is made up of the following reports, which can be publicly accessed at the MAS website at: www.health.gov.on.ca/mas or at www.health.gov.on.ca/english/providers/program/mas/mas_about.html Single Photon Emission Computed Tomography for the Diagnosis of Coronary Artery Disease: An Evidence-Based Analysis Stress Echocardiography for the Diagnosis of Coronary Artery Disease: An Evidence-Based Analysis Stress Echocardiography with Contrast for the Diagnosis of Coronary Artery Disease: An Evidence-Based Analysis 64-Slice Computed Tomographic Angiography for the Diagnosis of Coronary Artery Disease: An Evidence-Based Analysis Cardiac Magnetic Resonance Imaging for the Diagnosis of Coronary Artery Disease: An Evidence-Based Analysis Pease note that two related evidence-based analyses of non-invasive cardiac imaging technologies for the assessment of myocardial viability are also available on the MAS website: Positron Emission Tomography for the Assessment of Myocardial Viability: An Evidence-Based Analysis Magnetic Resonance Imaging for the Assessment of Myocardial Viability: an Evidence-Based Analysis The Toronto Health Economics and Technology Assessment Collaborative has also produced an associated economic report entitled: The Relative Cost-effectiveness of Five Non-invasive Cardiac Imaging Technologies for Diagnosing Coronary Artery Disease in Ontario [Internet]. Available from: http://theta.utoronto.ca/reports/?id=7 Objective The objective of this analysis was to determine the diagnostic accuracy of cardiac magnetic resonance imaging (MRI) for the diagnosis of patients with known/suspected coronary artery disease (CAD) compared to coronary angiography. Cardiac MRI Stress cardiac MRI is a non-invasive, x-ray free imaging technique that takes approximately 30 to 45 minutes to complete and can be performed using to two different methods, a) perfusion imaging following a first pass of an intravenous bolus of gadolinium contrast, or b) wall motion imaging. Stress is induced pharmacologically with either dobutamine, dipyridamole, or adenosine, as physical exercise is difficult to perform within the magnet bore and often induces motion artifacts. Alternatives to stress cardiac perfusion MRI include stress single-photon emission computed tomography (SPECT) and stress echocardiography (ECHO). The advantage of cardiac MRI is that it does not pose the radiation burden associated with SPECT. During the same sitting, cardiac MRI can also assess left and right ventricular dimensions, viability, and cardiac mass. It may also mitigate the need for invasive diagnostic coronary angiography in patients with intermediate risk factors for CAD. Evidence-Based Analysis Literature Search A literature search was perf

2010-01-01

131

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

132

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. PMID:24893292

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

2014-01-01

133

Wavelet-based image fusion and quality assessment  

Microsoft Academic Search

Recent developments in satellite and sensor technologies have provided high-resolution satellite images. Image fusion techniques can improve the quality, and increase the application of these data. This paper addresses two issues in image fusion (a) the image fusion method and (b) corresponding quality assessment.Firstly, a multi-band wavelet-based image fusion method is presented, which is a further development of the two-band

Wenzhong Shi; Changqing Zhu; Yan Tian; Janet Nichol

2005-01-01

134

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

135

Flow and distension in the carotid artery from magnetic resonance imaging  

NASA Astrophysics Data System (ADS)

Hemodynamic conditions in the carotid artery may be associated with progression of carotid artery (CA) disease and with the risk of stroke. A methodology for objective measurement of distension (DCA) and blood-flow (QCA) waveform from phase-contrast (PC) magnetic resonance (MR) imaging is presented. Measurement of DCA is obtained using a modified Hough Transform (mHT) applied to the magnitude-component of the PC MR. The mHT is based on the optimization of an objective function which is the sum of the gradient magnitude of the image sampled at 10° increments around the circle using bilinear interpolation. The mHT detects the boundary of the vessel in the cross-sectional image at 0.05-pixel resolution. Measurement of QCA is obtained by integration of the image intensity in the phase-component of the PC MR within the circular region detected by the mHT.

Yim, Peter J.; Demarco, J. K.

2004-04-01

136

Objective picture quality scale (PQS) for image coding  

Microsoft Academic Search

A new methodology for the determination of an objective metric for still image coding is reported. This methodology is applied to obtain a picture quality scale (PQS) for the coding of achromatic images over the full range of image quality defined by the subjective mean opinion score (MOS). This PQS takes into account the properties of visual perception for both

Makoto Miyahara; Kazunori Kotani; V. Ralph Algazi

1998-01-01

137

Coronary artery angiography and myocardial viability imaging: a 3.0-T contrast-enhanced magnetic resonance coronary artery angiography with Gd-BOPTA.  

PubMed

With improving MR sequence, phase-array coil and image quality, cardiac magnetic resonance imaging is becoming a promising method for a comprehensive non-invasive evaluation of coronary artery and myocardial viability. The study aimed to evaluate contrast-enhanced whole-heart coronary MR angiography (CE WH-CMRA) at 3.0-Tesla for the diagnosis of significant stenosis (?50%) and detection of myocardial infarction (MI) in patients with suspected coronary artery disease (CAD). CE WH-CMRA was performed in consecutive 70 patients with suspected CAD by using a 3.0-T MR system. A respiratory-gated, electrocardiography-triggered, inversion-recovery, segmented fast low angle shot sequence (TI = 200 ms) was used. Data acquisition began 60 s after the slow injection of Gd-BOPTA (0.2 mmol/kg body weight, at an injection rate 0.3 ml/s). At last, breath-hold 2D-PSIR-SSFP sequence was performed. Diagnostic accuracy of CE WH-CMRA in detecting significant stenosis (?50%) was evaluated using invasive coronary angiography as the referenced standard. The MI region appearing as high signal intensity visualized on CEWH-CMRA and 2D-PSIR-SSFP images were compared and analyzed. CE WH-CMRA correctly identified 42 of 44 patients with significant CAD. The overall sensitivity, specificity, negative predictive value, positive predictive value and accuracy for diagnosing significant CAD was 83.6, 95.8, 96.0, 82.8 and 93.4% respectively. The MI region detected by WH-CMRA and 2D-PSIR-SSFP were consistent in 10 patients and these segments manifested with transmural or subendocardial enhancement patterns. Only one MI patient was judged inconsistent between WH-CMRA and 2D-PSIR-SSFP, who was confirmed by clinical and electrocardiogram results. The enhancement pattern in this patient was spotted and focal in 2D-PSIR-SSFP, but was dismissed by WH-CMRA. It is feasible to obtain information about coronary artery stenosis and myocardial viability in a single CE WH-CMRA with administration of Gd-BOPTA. PMID:24068575

Yun, Hong; Jin, Hang; Yang, Shan; Huang, Dong; Chen, Zhang-wei; Zeng, Meng-su

2014-01-01

138

Intra-Arterial Thrombus Visualized on T2* Gradient Echo Imaging in Acute Ischemic Stroke  

Microsoft Academic Search

Background: MR signal loss related to arterial thrombosis leading to vascular susceptibility artifacts (VSA) has recently been reported on gradient echo images. The time course and sensitivity of VSA in acute stroke patients has been scarcely investigated. The aim of this study was to assess the frequency and course of VSA in acute stroke patients, to compare its sensitivity to

E. Assouline; K. Benziane; D. Reizine; J. P. Guichard; F. Pico; J. J. Merland; M. G. Bousser; H. Chabriat

2005-01-01

139

Carotid artery and aortic arch imaging with ECG gating in DSA  

SciTech Connect

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

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

1985-06-01

140

Image Quality Characteristics of Handheld Display Devices for Medical Imaging  

PubMed Central

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

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

2013-01-01

141

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

142

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

143

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

PubMed Central

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

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

2013-01-01

144

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

PubMed Central

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

145

Using short-wave infrared imaging for fruit quality evaluation  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

146

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. PMID:24152885

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

2014-01-01

147

LANDSAT-4 image data quality analysis  

NASA Technical Reports Server (NTRS)

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

Anuta, P. E. (principal investigator)

1982-01-01

148

Studying Satellite Image Quality Based on the Fusion Techniques  

E-print Network

Various and different methods can be used to produce high-resolution multispectral images from high-resolution panchromatic image (PAN) and low-resolution multispectral images (MS), mostly on the pixel level. However, the jury is still out on the benefits of a fused image compared to its original images. There is also a lack of measures for assessing the objective quality of the spatial resolution for the fusion methods. Therefore, an objective quality of the spatial resolution assessment for fusion images is required. So, this study attempts to develop a new qualitative assessment to evaluate the spatial quality of the pan sharpened images by many spatial quality metrics. Also, this paper deals with a comparison of various image fusion techniques based on pixel and feature fusion techniques.

Al-Wassai, Firouz Abdullah; Al-Zaky, Ali A

2011-01-01

149

Giant aneurysm in a left coronary artery fistula: diagnostic cardiovascular imaging and treatment considerations.  

PubMed

Congenital coronary artery fistula complicated with giant coronary artery aneurysm is a very rare condition. In this case report, we present a 65-year-old woman, referred to us with a continuous heart murmur, occasional atypical chest pain and few episodes of fainting. A giant aneurysm and a coronary-pulmonary fistula were diagnosed using multiple cardiovascular imaging modalities to provide a sufficient anatomical picture. The patient was considered at high risk of sudden death from aneurysm rupture and received surgical treatment. Subsequent histopathological examination revealed a true aneurysm with severe wall calcifications, ulcerations and large areas with marked thinning of the wall. The postoperative course was uneventful. PMID:23661653

Frestad, Daria; Helqvist, Steffen; Helvind, Morten; Kofoed, Klaus

2013-01-01

150

Detection of coronary artery disease using MR imaging with dipyridamole infusion  

SciTech Connect

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

Pennell, D.J.; Underwood, S.R.; Longmore, D.B. (National Heart and Lung Institute, London (England))

1990-03-01

151

Improving image quality of thermal imaging system by dynamically evening local histogram  

Microsoft Academic Search

Under the condition of being covered by anti-infrared smoke screen, the grayscales of infrared image becomes fairly concentrated, thus the contrast will be worse. In order to improve the image quality of thermal image of target and decrease the time of being covered by anti-infrared smoke, a new method of improving quality of thermal image by evening dynamic local histogram

Wenjian Chen; Zeying Chi; Xianjun Yue

2002-01-01

152

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

153

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

PubMed Central

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

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

2014-01-01

154

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

155

Three-Dimensional Black-Blood Cardiac Magnetic Resonance Coronary Vessel Wall Imaging Detects Positive Arterial Remodeling in Patients With Nonsignificant Coronary Artery Disease  

Microsoft Academic Search

Background—Direct noninvasive visualization of the coronary vessel wall may enhance risk stratification by quantifying subclinical coronary atherosclerotic plaque burden. We sought to evaluate high-resolution black-blood 3D cardiovas- cular magnetic resonance (CMR) imaging for in vivo visualization of the proximal coronary artery vessel wall. Methods and Results—Twelve adult subjects, including 6 clinically healthy subjects and 6 patients with nonsignificant coronary artery

W. Yong Kim; Matthias Stuber; Peter Börnert; Kraig V. Kissinger; Warren J. Manning; René M. Botnar

2002-01-01

156

Microfocal X-ray CT imaging and pulmonary arterial distensibility in excised rat lungs.  

PubMed

The objective of this study was to develop an X-ray computed tomographic method for measuring pulmonary arterial dimensions and locations within the intact rat lung. Lungs were removed from rats and their pulmonary arterial trees were filled with perfluorooctyl bromide to enhance X-ray absorbance. The lungs were rotated within the cone of the X-ray beam projected from a microfocal X-ray source onto an image intensifier, and 360 images were obtained at 1 degrees increments. The three-dimensional image volumes were reconstructed with isotropic resolution using a cone beam reconstruction algorithm. The vessel diameters were obtained by fitting a functional form to the image of the vessel circular cross section. The functional form was chosen to take into account the point spread function of the image acquisition and reconstruction system. The diameter measurements obtained over a range of vascular pressures were used to characterize the distensibility of the rat pulmonary arteries. The distensibility coefficient alpha [defined by D(P) = D(0)(1 + alphaP), where D(P) is the diameter at intravascular pressure (P)] was approximately 2.8% mmHg and independent of vessel diameter in the diameter range (about 100 to 2,000 mm) studied. PMID:11514318

Karau, K L; Johnson, R H; Molthen, R C; Dhyani, A H; Haworth, S T; Hanger, C C; Roerig, D L; Dawson, C A

2001-09-01

157

Analyzing and improving image quality in reflective ghost imaging  

E-print Network

Ghost imaging is a transverse imaging technique that relies on the correlation between a pair of light fields, one that has interacted with the object to be imaged and one that has not. Most ghost imaging experiments have ...

Hardy, Nicholas D. (Nicholas David)

2011-01-01

158

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

SciTech Connect

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

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

2013-03-15

159

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

160

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. PMID:22876346

Zhou, Xiaolin; Bedggood, Phillip; Metha, Andrew

2012-01-01

161

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.

2012-03-01

162

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

163

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

SciTech Connect

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

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

1986-03-01

164

Arterial input function derived from pairwise correlations between PET-image voxels  

PubMed Central

A metabolite corrected arterial input function is a prerequisite for quantification of positron emission tomography (PET) data by compartmental analysis. This quantitative approach is also necessary for radioligands without suitable reference regions in brain. The measurement is laborious and requires cannulation of a peripheral artery, a procedure that can be associated with patient discomfort and potential adverse events. A non invasive procedure for obtaining the arterial input function is thus preferable. In this study, we present a novel method to obtain image-derived input functions (IDIFs). The method is based on calculation of the Pearson correlation coefficient between the time-activity curves of voxel pairs in the PET image to localize voxels displaying blood-like behavior. The method was evaluated using data obtained in human studies with the radioligands [11C]flumazenil and [11C]AZ10419369, and its performance was compared with three previously published methods. The distribution volumes (VT) obtained using IDIFs were compared with those obtained using traditional arterial measurements. Overall, the agreement in VT was good (?3% difference) for input functions obtained using the pairwise correlation approach. This approach performed similarly or even better than the other methods, and could be considered in applied clinical studies. Applications to other radioligands are needed for further verification. PMID:23571279

Schain, Martin; Benjaminsson, Simon; Varnas, Katarina; Forsberg, Anton; Halldin, Christer; Lansner, Anders; Farde, Lars; Varrone, Andrea

2013-01-01

165

Telepresence and Video Games: The Impact of Image Quality  

Microsoft Academic Search

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

Cheryl Campanella Bracken; Paul Skalski

2009-01-01

166

Meat Quality Evaluation by Hyperspectral Imaging Technique: An Overview  

Microsoft Academic Search

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

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

2012-01-01

167

Tumor Encasement of the Right Coronary Artery: Role of Anatomic and Functional Imaging in Diagnosis and Therapeutic Management  

PubMed Central

We presented two rare cases of mediastinal tumor encasing the right coronary artery (RCA), one with recurrent metastatic thymoma and another with primary poorly differentiated neoplasm. Different degrees and locations of RCA involvement were noted. The treatment approach varied from conservative to surgical. Coronary artery involvement by mediastinal tumors is important to be investigated with imaging as it may guide the surgical planning.

Juan, Yu-Hsiang; Chatzizisis, Yiannis S; Saboo, Sachin S; Rocha, Tatiana; Steigner, Michael L

2014-01-01

168

New image quality assessment method using wavelet leader pyramids  

NASA Astrophysics Data System (ADS)

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

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

2011-06-01

169

Signal attenuation and box-counting fractal analysis of optical coherence tomography images of arterial tissue  

PubMed Central

The sensitivity of optical coherence tomography images to sample morphology is tested by two methods. The first method estimates the attenuation of the OCT signal from various regions of the probed tissue. The second method uses a box-counting algorithm to calculate the fractal dimensions in the regions of interest identified in the images. Although both the attenuation coefficient as well as the fractal dimension correlate very well with the anatomical features of the probed samples; the attenuation method provides a better sensitivity. Two types of samples are used in this study: segments of arteries collected from atherosclerosis–prone Watanabe rabbits (WHHL-MI) and healthy segments of porcine coronary arteries. PMID:21258464

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

2010-01-01

170

Signal attenuation and box-counting fractal analysis of optical coherence tomography images of arterial tissue.  

PubMed

The sensitivity of optical coherence tomography images to sample morphology is tested by two methods. The first method estimates the attenuation of the OCT signal from various regions of the probed tissue. The second method uses a box-counting algorithm to calculate the fractal dimensions in the regions of interest identified in the images. Although both the attenuation coefficient as well as the fractal dimension correlate very well with the anatomical features of the probed samples; the attenuation method provides a better sensitivity. Two types of samples are used in this study: segments of arteries collected from atherosclerosis-prone Watanabe rabbits (WHHL-MI) and healthy segments of porcine coronary arteries. PMID:21258464

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

2010-01-01

171

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

PubMed Central

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

Zaharchuk, Greg

2011-01-01

172

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. PMID:23865066

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

2013-01-01

173

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

PubMed

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

Kolaman, Amir; Yadid-Pecht, Orly

2012-04-01

174

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

SciTech Connect

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

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

1985-08-01

175

Rapid Progression of Symptomatic Vertebrobasilar Artery Dissection on Magnetic Resonance Imaging: A Case Report  

PubMed Central

Spontaneous intracranial vertebrobasilar dissection can manifest with various clinical symptoms, including subarachnoid hemorrhage or ischemic symptoms from impaired posterior circulation. A 29-year-old woman came to our emergency department with a sudden onset of left sided mild motor weakness and headache. Initial magnetic resonance imaging (MRI) showed mild luminal irregularities in the vertebrobasilar arteries with an eccentric periluminal hematoma. Follow-up MRI obtained 3 days later showed a progression of vertebrobasilar dissection to multifocal stenoses with an increased intramural hematoma.

Kwak, Hyo-Sung; Hwang, Seung Bae; Chung, Gyung Ho

2014-01-01

176

Interactive Guidance by Image Overlay in Robot Assisted Coronary Artery Bypass  

Microsoft Academic Search

\\u000a We present an original visual guidance system in the especially difficult context of robot assisted coronary artery bypass\\u000a graft. The overlay of a preoperative coronary tree model on the endoscopic images is initialized to help the surgeon to locate\\u000a himself. Then the surgeon points some landmarks observed in the operating field during the motion of the endoscope. The overlay\\u000a is

Fabien Mourgues; Thierry Viéville; Volkmar Falk; Ève Coste-manière

2003-01-01

177

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

PubMed

The practical aspects of the dosimetric and imaging performance of a digital x-ray system for cardiology procedures were evaluated. The system was configured with an image intensifier (II) and later upgraded to a dynamic flat panel detector (FD). Entrance surface air kerma (ESAK) to phantoms of 16, 20, 24 and 28 cm of polymethyl methacrylate (PMMA) and the image quality of a test object were measured. Images were evaluated directly on the monitor and with numerical methods (noise and signal-to-noise ratio). Information contained in the DICOM header for dosimetry audit purposes was also tested. ESAK values per frame (or kerma rate) for the most commonly used cine and fluoroscopy modes for different PMMA thicknesses and for field sizes of 17 and 23 cm for II, and 20 and 25 cm for FD, produced similar results in the evaluated system with both technologies, ranging between 19 and 589 microGy/frame (cine) and 5 and 95 mGy min(-1) (fluoroscopy). Image quality for these dose settings was better for the FD version. The 'study dosimetric report' is comprehensive, and its numerical content is sufficiently accurate. There is potential in the future to set those systems with dynamic FD to lower doses than are possible in the current II versions, especially for digital cine runs, or to benefit from improved image quality. PMID:16306664

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

2005-12-01

178

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

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

179

Coronary imaging quality in routine ECG-gated multidetector CT examinations of the entire thorax: preliminary experience with a 64-slice CT system in 133 patients  

Microsoft Academic Search

To evaluate image quality in the assessment of the coronary arteries during routine ECG-gated multidetector CT (MDCT) of the\\u000a chest. One hundred and thirty three patients in sinus rhythm underwent an ECG-gated CT angiographic examination of the entire\\u000a chest without ?-blockers with a 64-slice CT system. In 127 patients (95%), it was possible to assess the coronary arteries\\u000a partially or

Damien Delhaye; Martine Remy-Jardin; Randa Salem; Antoine Teisseire; Chadi Khalil; Valérie Delannoy-Deken; Alain Duhamel; Jacques Remy

2007-01-01

180

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. PMID:24865208

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

2014-01-01

181

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

182

Estimating and Fusing Quality Factors for Iris Biometric Images  

Microsoft Academic Search

Iris recognition, the ability to recognize and distinguish individuals by their iris pattern, is one of the most reliable biometrics in terms of recognition and identification performance. However, the performance of these systems is affected by poor-quality imaging. In this paper, we extend iris quality assessment research by analyzing the effect of various quality factors such as defocus blur, off-angle,

Nathan D. Kalka; Jinyu Zuo; Natalia A. Schmid; Bojan Cukic

2010-01-01

183

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

184

The influence of different technique factors on image quality of chest radiographs as evaluated by modified CEC image quality criteria  

Microsoft Academic Search

The Commission of the European Communities (CEC) research project ''Predictivity and optimisation in medical radiation protection'' addressed fundamental operational limitations in existing radiation protection mechanisms. The first part of the project aimed at investigating (1) whether the CEC image quality criteria could be used for optimization of a radiographic process and (2) whether significant differences in image quality based on

B LANHEDE; MB ATH; S KHEDDACHE; P SUND; L BJORNELD; M WIDELL; A ALMEN; J BESJAKOV; S MATTSSON; A TINGBERG; W PANZER; M ZANKL

185

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

SciTech Connect

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.

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

2007-09-15

186

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. PMID:17671809

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

2007-01-01

187

The effects of piston error on image quality of synthetical aperture optical imaging system  

NASA Astrophysics Data System (ADS)

The relationship between image quality and piston errors of synthetical aperture optical imaging system has been studied. An active segmented cophasing imaging system and its Zemax simulation model were set up. Diversity piston errors were introduced and the corresponding MTF were calculated with the Zemax simulation model. Simulation experiments have been carried out with the cophasing imaging system, and the results are coincident with the simulated results. The results show that image quality changes with the increase of the piston error periodically if the piston error is smaller than the coherent length of the light source, and the image quality becomes the worst if the piston error is an odd multiple of ?.

Zhang, Jun; Zhao, Weirui; Yang, Feng; Zhang, Lifang

2012-11-01

188

Identification of suitable fundus images using automated quality assessment methods.  

PubMed

Retinal image quality assessment (IQA) is a crucial process for automated retinal image analysis systems to obtain an accurate and successful diagnosis of retinal diseases. Consequently, the first step in a good retinal image analysis system is measuring the quality of the input image. We present an approach for finding medically suitable retinal images for retinal diagnosis. We used a three-class grading system that consists of good, bad, and outlier classes. We created a retinal image quality dataset with a total of 216 consecutive images called the Diabetic Retinopathy Image Database. We identified the suitable images within the good images for automatic retinal image analysis systems using a novel method. Subsequently, we evaluated our retinal image suitability approach using the Digital Retinal Images for Vessel Extraction and Standard Diabetic Retinopathy Database Calibration level 1 public datasets. The results were measured through the F1 metric, which is a harmonic mean of precision and recall metrics. The highest F1 scores of the IQA tests were 99.60%, 96.50%, and 85.00% for good, bad, and outlier classes, respectively. Additionally, the accuracy of our suitable image detection approach was 98.08%. Our approach can be integrated into any automatic retinal analysis system with sufficient performance scores. PMID:24718384

?evik, U?ur; Köse, Cemal; Berber, Tolga; Erdöl, Hidayet

2014-04-01

189

A novel similarity based quality metric for image fusion  

Microsoft Academic Search

A novel objective quality metric for image fusion is presented. The interest of our metric lies in the fact that the redundant regions and the complementary\\/conflicting regions are treated respectively according to the structural similarity between the source images. The experiments show that the proposed measure is consistent with human visual evaluations and can be applied to evaluate image fusion

Cui Yang; Jian-qi Zhang; Xiao-rui Wang; Xin Liu

2008-01-01

190

Analysis of the quality of laser images of diffuse objects  

Microsoft Academic Search

An analysis is made of the combined influence of the resolving power of an optical system and of the high coherence of laser radiation on the quality of the images of diffuse objects. An experimental dependence is given of the number of spots in an image on the resolving power and a histogram of intensities in a laser image is

N. D. Ustinov; P. A. Bakut; V. V. Barinov; L. A. Deviatkov; V. I. Mandrosov; I. N. Troitskii

1978-01-01

191

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

192

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

PubMed

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

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

2013-10-15

193

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

PubMed Central

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

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

2013-01-01

194

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

PubMed Central

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

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

2013-01-01

195

Testing scanners for the quality of output images  

NASA Astrophysics Data System (ADS)

Document scanning is the means through which documents are converted to their digital image representation for electronic storage or distribution. Among the types of documents being scanned by government agencies are tax forms, patent documents, office correspondence, mail pieces, engineering drawings, microfilm, archived historical papers, and fingerprint cards. Increasingly, the resulting digital images are used as the input for further automated processing including: conversion to a full-text-searchable representation via machine printed or handwritten (optical) character recognition (OCR), postal zone identification, raster-to-vector conversion, and fingerprint matching. These diverse document images may be bi-tonal, gray scale, or color. Spatial sampling frequencies range from about 200 pixels per inch to over 1,000. The quality of the digital images can have a major effect on the accuracy and speed of any subsequent automated processing, as well as on any human-based processing which may be required. During imaging system design, there is, therefore, a need to specify the criteria by which image quality will be judged and, prior to system acceptance, to measure the quality of images produced. Unfortunately, there are few, if any, agreed-upon techniques for measuring document image quality objectively. In the output images, it is difficult to distinguish image degradation caused by the poor quality of the input paper or microfilm from that caused by the scanning system. We propose several document image quality criteria and have developed techniques for their measurement. These criteria include spatial resolution, geometric image accuracy, (distortion), gray scale resolution and linearity, and temporal and spatial uniformity. The measurement of these criteria requires scanning one or more test targets along with computer-based analyses of the test target images.

Concepcion, Vicente P.; Nadel, Lawrence D.; D'Amato, Donald P.

1995-01-01

196

[Optical coherence tomography of coronary arteries--a novel intravascular imaging modality].  

PubMed

Optical coherence tomography (OCT) is the latest intravascular imaging modality for the investigation of coronary arteries. It can be used in patients with stable coronary artery disease as well as in patients with acute coronary syndrome. Its almost microscope-like resolution of 10-20 ?m (10-times greater than intravascular ultrasound) gives us the most detailed insight into the coronary artery wall in vivo so far.Optical coherence tomography can be used for accurate qualitative and quantitative assessment of stenoses in stable coronary artery disease and accurate guidance of percutaneous coronary interventions as well as accurate postprocedural control. In patients with acute coronary syndrome it can be used for the detection of culprit of the culprit lesion (vulnerable plaque) which allows the operator to cover not only angiographically tightest stenosis (angiographic culprit lesion, caused in most cases by thrombus only) but most importantly the vulnerable plaque, which led to the acute event, as well. Furthermore, optical coherence tomography allows accurate assessment of thrombotic burden, stent apposition/malapposition, edge dissections and tissue prolaps or thrombus protrusions throught stent struts, etc. PMID:25225864

Mrevlje, B; Legutko, J; J?ka?a, J; No?, M; Dudek, D; Birkemeyer, R; Aboukoura, M; Nienaber, C

2014-09-01

197

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

198

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

PubMed Central

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

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

2011-01-01

199

Quality criteria for simulator images - A literature review  

Microsoft Academic Search

Quality criteria are presented for each of about 30 different outside-world image features of computer-generated image systems on vehicle simulators (e.g., airplane, tank, ship). Criteria derived are based on a literature review. In addition to purely physical properties related to image presentation (e.g., field size, contrast ratio, update frequency), attention is paid to image content (e.g., number of polygons, surface

Pieter Padmos; Maarten V. Milders

1992-01-01

200

SAR image quality using advanced pulse compression noise (APCN)  

NASA Astrophysics Data System (ADS)

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

Govoni, Mark A.; Elwell, Ryan A.

2014-05-01

201

Recording of high-quality 3D images by holoprinter  

Microsoft Academic Search

Holographic (3-D) printer (holoprinter) is under development as a peripheral device for 3-D image processing systems. For the automatic printing of distortion-free image, `multidot' recording method is developed. In this paper, the technique for the synthesis of high-quality and gray-level images is presented, and the experimental results are demonstrated. Also the method to record full-color image is introduced.

Masahiro Yamaguchi; Hideaki Endoh; Toshio Honda; Nagaaki Ohyama

1993-01-01

202

High quality image oriented telemedicine with multimedia technology.  

PubMed

Researchers at Osaka and Kyoto University hospital performed three experiments, beginning in 1995, which looked at high quality-oriented telemedicine. This paper describes the system design for the three projects. Experiment 1 applied high-definition TV images and B-ISDN for distance learning and medical information exchange. Experiment 2 developed a super high-definition medical image filing system and the images were transmitted via B-ISDN for teleconferences and experiment 3 utilized digital, high-definition, TV images and communication satellites for teleconferences. Multimedia and communication technologies were considered to be fundamental components of telemedicine. The three projects were evaluated initially for quality of images, operability and utility. The experimental design and its implementation showed that it was possible to provide high quality image-oriented telemedicine in the health care environment. Obstacles to establishing practical telemedicine are also discussed. PMID:10471238

Takeda, H; Minato, K; Takahasi, T

1999-07-01

203

Image quality assessment by preprocessing and full reference model combination  

NASA Astrophysics Data System (ADS)

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

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

2009-01-01

204

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. PMID:24895593

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

2014-01-01

205

Effect of eicosapentaenoic acid on regional arterial stiffness: Assessment by tissue Doppler imaging  

PubMed Central

AIM: To evaluate the effects of eicosapentaenoic acid (EPA) on regional arterial stiffness assessed by strain rate using tissue Doppler imaging. METHODS: Nineteen eligible patients were prospectively studied (mean age 62 ± 8 years, 68% men). Subjects with large vessel complications and/or diabetes mellitus were excluded. The strain rate of the ascending aorta was measured by tissue Doppler imaging as an index of regional arterial stiffness, and brachial-ankle pulse wave velocity (baPWV) was measured as an index of degree of systemic arteriosclerosis. These indices were compared before and after administration of EPA at 1800 mg/d for one year. RESULTS: The plasma concentration of EPA increased significantly after EPA administration (3.0% ± 1.1% to 8.5% ± 2.9%, P < 0.001). There were no significant changes in baPWV (1765 ± 335 cm/s to 1745 ± 374 cm/s), low-density lipoprotein cholesterol levels (114 ± 29 mg/dL to 108 ± 28 mg/dL), or systolic blood pressure (131 ± 16 mmHg to 130 ± 13 mmHg) before and after EPA administration. In contrast, the strain rate was significantly increased by administration of EPA (19.2 ± 5.6 s-1, 23.0 ± 6.6 s-1, P < 0.05). CONCLUSION: One year of administration of EPA resulted in an improvement in regional arterial stiffness which was independent of blood pressure or serum cholesterol levels. PMID:22953023

Haiden, Mio; Miyasaka, Yoko; Kimura, Yutaka; Tsujimoto, Satoshi; Maeba, Hirofumi; Suwa, Yoshinobu; Iwasaka, Toshiji; Shiojima, Ichiro

2012-01-01

206

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

2008-03-01

207

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

PubMed

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

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

2014-11-01

208

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

PubMed Central

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

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

2014-01-01

209

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. PMID:24748773

Bak, Ewelina; Marcisz, Czeslaw

2014-01-01

210

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

SciTech Connect

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

Klooster, R. van 't; Staring, M.; Reiber, J. H. C.; Lelieveldt, B. P. F.; Geest, R. J. van der, E-mail: rvdgeest@lumc.nl [Department of Radiology, Division of Image Processing, Leiden University Medical Center, 2300 RC Leiden (Netherlands); Klein, S. [Department of Radiology and Department of Medical Informatics, Biomedical Imaging Group Rotterdam, Erasmus MC, Rotterdam 3015 GE (Netherlands)] [Department of Radiology and Department of Medical Informatics, Biomedical Imaging Group Rotterdam, Erasmus MC, Rotterdam 3015 GE (Netherlands); Kwee, R. M.; Kooi, M. E. [Department of Radiology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht 6202 AZ (Netherlands)] [Department of Radiology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht 6202 AZ (Netherlands)

2013-12-15

211

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

212

Perceptual image quality: Effects of tone characteristics  

E-print Network

Commonwealth Drive Menlo Park, California 94025 Xuemei Zhang Agilent Technologies Laboratories 3500 Deer Creek ratings.5­7 Here we apply similar experimental methods to study the relation between image tone charac the tone characteristics of the image. By tone characteristics we mean the distribution of the luminance

Brainard, David H.

213

Segmented primary mirror telescope image quality estimation  

Microsoft Academic Search

The model of distortions caused by mistakes in installation of mirrors of a compound telescope of the large diameter is offered. The results, received on the basis of model, calculated according to the formulas for average image in a plane of its formation, it variance and characteristic of speckle structure of the image are resulted. It is shown, that the

Yury P. Shumilov; Peter A. Bakut; Irina A. Grishina; Victor V. Sychev

2000-01-01

214

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

215

Need for an image quality assurance program in clinical teleradiology  

NASA Astrophysics Data System (ADS)

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

Telepak, Robert J.; Kelsey, Charles A.

1995-05-01

216

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

217

Applying image quality in cell phone cameras: lens distortion  

NASA Astrophysics Data System (ADS)

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

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

2009-01-01

218

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

NASA Astrophysics Data System (ADS)

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 those contributors to image quality to which a human interpreter is most sensitive. The main drawback to using a NIIRS rating as a measure of image quality in engineering trade studies is the fact that it is tied to the human observer and cannot be predicted from physical principles and engineering parameters alone. The General Image Quality Equation (GIQE) of Leachtenauer et al. 1997 [Appl. Opt. 36, 8322-8328 (1997)] is a regression of actual image analyst NIIRS ratings vs. readily calculable engineering metrics, and provides a mechanism for using the expected NIIRS rating of an imaging system in the design and evaluation process. In this paper, we will discuss how we use the GIQE in conjunction with The Aerospace Corporation's Parameterized Image Chain Analysis & Simulation SOftware (PICASSO) to evaluate imager designs, taking a hypothetical high resolution commercial imaging system as an example.

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

2009-08-01

219

Women with coronary artery disease report worse health-related quality of life outcomes compared to men  

Microsoft Academic Search

BACKGROUND: Although there have been substantial medical advances that improve the outcomes following cardiac ischemic events, gender differences in the treatment and course of recovery for patients with coronary artery disease (CAD) continue to exist. There is a general paucity of data comparing the health related quality of life (HRQOL) in men and women undergoing treatment for CAD. The purpose

Colleen M Norris; William A Ghali; P Diane Galbraith; Michelle M Graham; Louise A Jensen; Merril L Knudtson

2004-01-01

220

The image importance approach to human vision based image quality characterization  

Microsoft Academic Search

Characterization of image quality is an elusive concept which has been approached in various ways, from quantitative methods based on signal and information theory, to subjective psychovisual or task related assessment. The productive application of these approaches depends closely on the purpose for which the image quality indication is needed, and in many cases the different approaches provide contradictory indications.

Anthony J. Maeder

2005-01-01

221

Document image segmentation and quality improvement by moiré pattern analysis  

Microsoft Academic Search

Moiré patterns are distortions on the results of scanning printed documents. However, the patterns can be utilized in document image segmentation and quality improvement. The moiré phenomenon comes from sampling periodical structures in images, such as halftone screens, color components, and text galleys which often appear in printed magazines and newspapers. The generated moiré patterns appear in the scanning result

James Ching-Yu Yang; Wen-Hsiang Tsai

2000-01-01

222

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

223

Surface Appearance of the Vertebrobasilar Artery Revealed on Basiparallel Anatomic Scanning (BPAS)MR Imaging: Its Role for Brain MR Examination  

Microsoft Academic Search

PURPOSE: Basiparallel anatomic scanning (BPAS)-MR imaging is a simple MR imaging technique that we designed for visualization of the surface appearance of the vertebrobasilar artery within the cistern. It can clearly show the outer contour of occluded arteries or thrombosed aneurysms. By comparing BPAS-MR imaging with 3D time-of-flight (TOF) MR angiography (MRA), we can precisely evaluate the vertebrobasilar artery condition.

Morio Nagahata; Yoshinao Abe; Shuichi Ono; Takaaki Hosoya; Seiyu Uno

224

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

PubMed

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

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

2014-07-01

225

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

226

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

PubMed Central

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

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

2012-01-01

227

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

228

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

229

Evaluating the Sensitivity of Image Fusion Quality Metrics to Image Degradation in Satellite Imagery  

Microsoft Academic Search

Referring to the high potential of topographic satellite in collecting high resolution panchromatic imagery and high spectral,\\u000a multi spectral imagery, the purpose of image fusion is to produce a new image data with high spatial and spectral characteristics.\\u000a It is necessary to evaluate the quality of fused image by some quality metrics before using this product in various applications.\\u000a Up

Farhad Samadzadegan; Farzaneh DadrasJavan

230

The Effect of Motion Blur and Signal Noise on Image Quality in Low Light Imaging  

Microsoft Academic Search

Motion blur and signal noise are probably the two most dominant sources of image quality degradation in digital imaging. In\\u000a low light conditions, the image quality is always a tradeoff between motion blur and noise. Long exposure time is required\\u000a in low illumination level in order to obtain adequate signal to noise ratio. On the other hand, risk of motion

Eero Kurimo; Leena Lepistö; Jarno Nikkanen; Juuso Grén; Iivari Kunttu; Jorma Laaksonen

2009-01-01

231

Black-Blood Multicontrast Imaging of Carotid Arteries with DANTE-prepared 2D and 3D MR Imaging.  

PubMed

Purpose To prospectively compare the black-blood ( BB black blood ) imaging efficiency of a delay alternating with nutation for tailored excitation ( DANTE delay alternating with nutation for tailored excitation ) preparation module with conventional double inversion-recovery ( DIR double inversion recovery ) and motion-sensitive driven equilibrium ( MSDE motion-sensitive driven equilibrium ) preparation modules and to introduce a new three-dimensional ( 3D three-dimensional ) T1-weighted magnetic resonance (MR) imaging sequence. Materials and Methods Carotid artery wall imaging was performed in 10 healthy volunteers and 15 patients in accordance with an institutional review board-approved protocol. Two-dimensional ( 2D two-dimensional ) turbo spin-echo ( TSE turbo spin echo ) and 3D three-dimensional fast low-angle shot ( FLASH fast low-angle shot ) sequences served as readout modules. DANTE delay alternating with nutation for tailored excitation -prepared T1-, T2-, and proton density-weighted 2D two-dimensional TSE turbo spin echo images, as well as T1-weighted 3D three-dimensional DANTE delay alternating with nutation for tailored excitation -prepared FLASH fast low-angle shot (hereafter, 3D three-dimensional DASH DANTE-prepared FLASH ) images, were acquired in the region of the carotid artery bifurcation. For comparison, 2D two-dimensional DIR double inversion recovery -prepared, 2D two-dimensional MSDE motion-sensitive driven equilibrium -prepared multicontrast TSE turbo spin echo , and 3D three-dimensional MSDE motion-sensitive driven equilibrium -prepared FLASH fast low-angle shot (hereafter, 3D three-dimensional MERGE MSDE-prepared FLASH ) MR images were also acquired. The effective contrast-to-noise ratio ( CNReff effective contrast-to-noise ratio ) per unit time was calculated for all sequences. Paired t tests were performed to test within-group differences in vessel wall CNReff effective contrast-to-noise ratio . Results The CNReff effective contrast-to-noise ratio of DANTE delay alternating with nutation for tailored excitation -prepared T1-, T2-, and proton density-weighted sequences was 27.3, 14.7, and 25.7 mm(-1)min(-1/2), respectively; this represented an improvement of approximately 25%-100% (P < .05) when compared with the CNReff effective contrast-to-noise ratio attained with existing methods. The 3D three-dimensional DASH DANTE-prepared FLASH technique proved to be a fast (<2 seconds per section) and high-spatial-resolution (0.6 mm isotropic) BB black blood technique with higher (75%-100% improvement, P < .001) signal-to-noise ratio efficiency than the 3D three-dimensional MERGE MSDE-prepared FLASH technique. Conclusion The DANTE delay alternating with nutation for tailored excitation -prepared multicontrast 2D two-dimensional BB black blood technique is a promising new tool for MR imaging of carotid artery walls. Additionally, the 3D three-dimensional DASH DANTE-prepared FLASH sequence enables 3D three-dimensional high-spatial-resolution fast T1-weighted imaging of carotid artery walls. ©RSNA, 2014 Online supplemental material is available for this article . PMID:24918958

Li, Linqing; Chai, Joshua T; Biasiolli, Luca; Robson, Matthew D; Choudhury, Robin P; Handa, Ashok I; Near, Jamie; Jezzard, Peter

2014-11-01

232

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

NASA Astrophysics Data System (ADS)

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

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

2001-06-01

233

Relationship of subjective ratings of image quality and observer performance  

NASA Astrophysics Data System (ADS)

The relationship between radiologists' perception of image quality and their actual performance was assessed. If the two variables are strongly correlated, the easier obtained perception of quality index might be used as a prerequisite test to determine if a ROC study is justified. One-hundred seventy cases were evaluated for the presence or absence of interstitial disease and nodules by nine readers using seven display modes. Each reader also assigned each image a mode- specific perceived quality rating using a 5-category ordinal scale. Average perceived quality was highest for conventional film. It was slightly poorer for the subsets of cases with interstitial disease and for cases classified independently as 'subtle.' Trend tests indicated a relationship between area under the ROC curves (Az) and perceived image quality for nodules. For interstitial disease, the relationship was weaker and of borderline statistical significance. The subjective image quality index was related to the area under the ROC curve, but the average difference between pairs of display modes was not a good predictor of difference in actual observer performances. A subjective quality index may have limited usefulness in screening differences between modalities prior to the performance of a ROC study.

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

1997-04-01

234

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. PMID:24847387

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

2014-01-01

235

Improving high resolution retinal image quality using speckle illumination HiLo imaging  

PubMed Central

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

Zhou, Xiaolin; Bedggood, Phillip; Metha, Andrew

2014-01-01

236

Peripheral Aberrations and Image Quality for Contact Lens Correction  

PubMed Central

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

Shen, Jie; Thibos, Larry N.

2011-01-01

237

LANDSAT-4 image data quality analysis  

NASA Technical Reports Server (NTRS)

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

Anuta, P. E.

1984-01-01

238

Superhigh Quality Colour Image TV System Telan  

Microsoft Academic Search

Among the shortcomings of TV system of high sharpness is that fact that the problem of increasing of noise suppression is not solved jet. In the digital TV the problem of increasing image sharpness is not solved. Their common shortcoming is their bad compatibility with existing systems of standard TV and very high complicativeness and cost. The perspective alternative to

Alexander A. Antonov

1998-01-01

239

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

240

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

241

Characterization of the image quality in neutron radioscopy  

NASA Astrophysics Data System (ADS)

Neutron radioscopy, or dynamic neutron radiography, is a non-destructive testing method, which has made big steps in the last years. Depending on the neutron flux, the object and the detector, for single events a time resolution down to a few milliseconds is possible. In the case of repetitive processes the object can be synchronized with the detector and better statistics in the image can be reached by adding radiographies of the same phase with a time resolution down to 100 ?s. By stepwise delaying the trigger signal a radiography movie can be composed. Radiography images of a combustion engine and an injection nozzle were evaluated quantitatively by different methods trying to characterize the image quality of an imaging system. The main factors which influence the image quality are listed and discussed.

Brunner, J.; Engelhardt, M.; Frei, G.; Gildemeister, A.; Lehmann, E.; Hillenbach, A.; Schillinger, B.

2005-04-01

242

Quantitative analysis of dipyridamole-thallium images for the detection of coronary artery disease  

SciTech Connect

To determine if the detection of coronary artery disease by dipyridamole-thallium imaging is improved by quantitative versus qualitative analysis, and combining quantitative variables, 80 patients with chest pain (53 with and 27 without coronary artery disease) who underwent cardiac catheterization were studied. Segmental thallium initial uptake, linear clearance, monoexponential clearance and redistribution were measured from early, intermediate and delayed images acquired in three projections. Normal values were determined from 13 other clinically normal subjects. When five segments per view were used for quantitative analysis, sensitivity and specificity were 87 and 63%, respectively, for uptake, 77 and 67% for linear clearance, 60 and 60% for monoexponential clearance and 62 and 56% for redistribution. Of the four variables, uptake and linear clearance were the most sensitive (p less than 0.01) and specificity did not differ significantly. Using three segments per view, the specificity of uptake increased to 78% without a significant change in sensitivity (85%). With this approach, sensitivity and specificity did not differ from those of qualitative analysis (85 and 78%, respectively). Stepwise logistic regression analysis demonstrated that the best quantitative thallium correlate of the presence of coronary artery disease was a combination variable of ''either abnormal uptake or abnormal linear clearance, or both.'' Using five segments per view, the model's specificity (85%) was greater than that of uptake alone, with similar sensitivity (92%). Using three segments per view, the model's specificity (93%) was greater than that of uptake alone and of qualitative analysis (p less than 0.05), with similar sensitivity (85%).

Ruddy, T.D.; Dighero, H.R.; Newell, J.B.; Pohost, G.M.; Strauss, H.W.; Okada, R.D.; Boucher, C.A.

1987-07-01

243

[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

244

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

245

Imaging and analysis of lenticulostriate arteries using 7.0-Tesla magnetic resonance angiography.  

PubMed

The purpose of this study was to analyze human lenticulostriate arteries (LSAs) obtained non-invasively by 7.0-T MRI. A three-dimensional time-of-flight (3D TOF) magnetic resonance angiography (MRA) technique was used with an investigational 7.0-T MRI scanner with a radio-frequency coil that was optimized and designed for angiographic purposes. We obtained images from 16 healthy volunteers (8 males and 8 females, mean age 21 +/- 2.7 years). For direct comparison of LSA images with digital subtraction angiography (DSA), we also obtained 7.0-T MRA and DSA images from one patient, a 27-year-old woman with a posterior fossa arteriovenous malformation (AVM). We then analyzed the characteristics of LSAs using a custom data analysis method with MatLab for quantitative analysis. Analysis of LSA images included shape and number of branches and origins, findings that are essential and useful for quantification of LSA abnormalities in both healthy controls and patients. Ultra-high-field MRA provided clear anatomic delineation of the LSAs, thereby suggesting that 7.0-T MRA may be a promising technique for microvascular imaging of the LSAs. PMID:19097221

Kang, Chang-Ki; Park, Cheol-Wan; Han, Jae-Yong; Kim, Sang-Hoon; Park, Chan-A; Kim, Kyoung-Nam; Hong, Suk-Min; Kim, Young-Bo; Lee, Kendall H; Cho, Zang-Hee

2009-01-01

246

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

SciTech Connect

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

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

1981-04-01

247

APQ-102 imaging radar digital image quality study  

NASA Technical Reports Server (NTRS)

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.

1982-01-01

248

Body image and quality of life in a Spanish population  

PubMed Central

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

Lobera, Ignacio Jauregui; Rios, Patricia Bolanos

2011-01-01

249

a New System for Estimating Sclerosis of IN VIVO Common Carotid Artery by Ultrasound B-Mode Image Analysis  

NASA Astrophysics Data System (ADS)

A new system has been developed for estimating sclerosis of in vivo common carotid artery by ultrasound B-mode (Brightness-mode) image analysis. The method is based on in vivo stiffness, Eth, calculated from the variation of carotid-duct-diameter with changing of systolic and diastolic blood pressures. In addition from the results of tensile and internal pressure burst test using in vitro human and animal arteries specimens, we found a correlation between in vitro Eths estimated from stress-strain curve of radial and tensile tests by subjecting step by step loads. Thus, using a correlation curve a technique for estimating in vivo Eth as well as tensile strength of carotid artery can be predicted. Then, to be a simple routine medical examination, a prototype software was developed, which is capable to measure the diameter changes by the image processing based on 30-image/s and one pixel size data (in case of the report, 0.0713 mm/pixel) of an ultrasound device. The total examination time for both sides of the common carotid arteries was within 300 seconds. To examine the validity of this technique, some clinical data is presented. The result indicated that the stiffness (Eth), strength, and critical burst pressure are useful symptom indices for arterial sclerosis, especially for finding the beginning sclerosis that would start early twenties.

Nogata, Fumio; Yokota, Yasunari; Kawamura, Yoko; Walsh, W. R.

2009-08-01

250

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

251

Novel image fusion quality metrics based on sensor models and image statistics  

NASA Astrophysics Data System (ADS)

This paper presents progress in image fusion modeling. One fusion quality metric based on the Targeting Task performance (TTP) metric and another based on entropy are presented. A human perception test was performed with fused imagery to determine effectiveness of the metrics in predicting image fusion quality. Both fusion metrics first establish which of two source images is ideal in a particular spatial frequency pass band. The fused output of a given algorithm is then measured against this ideal in each pass band. The entropy based fusion quality metric (E-FQM) uses statistical information (entropy) from the images while the Targeting Task Performance fusion quality metric (TTPFQM) utilizes the TTP metric value in each spatial frequency band. This TTP metric value is the measure of available excess contrast determined by the Contrast Threshold Function (CTF) of the source system and the target contrast. The paper also proposes an image fusion algorithm that chooses source image contributions using a quality measure similar to the TTP-FQM. To test the effectiveness of TTP-FQM and E-FQM in predicting human image quality preferences, SWIR and LWIR imagery of tanks were fused using four different algorithms. A paired comparison test was performed with both source and fused imagery as stimuli. Eleven observers were asked to select which image enabled them to better identify the target. Over the ensemble of test images, the experiment showed that both TTP-FQM and E-FQM were capable of identifying the fusion algorithms most and least preferred by human observers. Analysis also showed that the performance of the TTP-FQM and E-FQM in identifying human image preferences are better than existing fusion quality metrics such as the Weighted Fusion Quality Index and Mutual Information.

Smith, Forrest A.; Chari, Srikant; Halford, Carl E.; Fanning, Jonathan; Reynolds, Joseph P.

2009-05-01

252

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

PubMed Central

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

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

2014-01-01

253

An information fidelity criterion for image quality assessment using natural scene statistics  

Microsoft Academic Search

Measurement of visual quality is of fundamental im- portance to numerous image and video processing applications. The goal of quality assessment (QA) research is to design algo- rithms that can automatically assess the quality of images or videos in a perceptually consistent manner. Traditionally, image QA algo- rithms interpret image quality as fidelity or similarity with a \\

Hamid Rahim Sheikh; Alan Conrad Bovik; Gustavo De Veciana

2005-01-01

254

No-reference image quality assessment using shearlet transform  

NASA Astrophysics Data System (ADS)

Image and video quality measurements are crucial for many applications, such as acquisition, compression, transmission, enhancement, and reproduction. Nowadays, no-reference (NR) image quality assessment (IQA) methods have been drawn extensive attention because it does not need any information of reference images. However, most proposed NR IQA methods are designed only for one or a set of predefined specific distortion types, which are unlikely to generalize for evaluating images distorted with other types of distortions. In order to estimate a wide range of image distortions, in this paper, a novel NR IQA method is proposed which is based on shearlet transform, a new multiscale directional transform with a strong ability to localize distributed discontinuities. The distorted image leads to significant variation in the distributed discontinuities in all directions. Thus, the statistical property of the distorted image is significantly different from that of natural images in shearlet domain. A new model is also proposed to measure this difference. Numerical experiments demonstrate that this new NR IQA method is consistent with subjective assessment, very effective for many well-known types of image distortions and superior to some existing prominent methods.

Li, Yuming; Cao, Hanqiang; Xu, Zijian

2013-10-01

255

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

PubMed

The high spatial resolution of micro-computed tomography (micro-CT) is ideal for 3D imaging of coronary arteries in intact mouse heart specimens. Previously, micro-CT of mouse heart specimens utilized intravascular contrast agents that hardened within the vessel lumen and allowed a vascular cast to be made. However, for mouse coronary artery disease models, it is highly desirable to image coronary artery walls and highlight plaques. For this purpose, we describe an ex vivo contrast-enhanced micro-CT imaging technique based on tissue staining with osmium tetroxide (OsO(4) ) solution. As a tissue-staining contrast agent, OsO(4) is retained in the vessel wall and surrounding tissue during the fixation process and cleared from the vessel lumens. Its high X-ray attenuation makes the artery wall visible in CT. Additionally, since OsO(4) preferentially binds to lipids, it highlights lipid deposition in the artery wall. We performed micro-CT of heart specimens of 5- to 25-week-old C57BL/6 wild-type mice and 5- to 13-week-old apolipoprotein E knockout (apoE(-/-) ) mice at 10 ?m resolution. The results show that walls of coronary arteries as small as 45 ?m in diameter are visible using a table-top micro-CT scanner. Similar image clarity was achieved with 1/2000th the scan time using a synchrotron CT scanner. In 13-week-old apoE mice, lipid-rich plaques are visible in the aorta. Our study shows that the combination of OsO(4) and micro-CT permits the visualization of the coronary artery wall in intact mouse hearts. PMID:22360411

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

2012-05-01

256

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

SciTech Connect

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

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

2012-05-10

257

Sensor Fused Night Vision : Assessing Image Quality in the Lab and in the Field  

Microsoft Academic Search

Generating real-time fused combinations of VNIR, SWIR and LWIR imagery enhances situational awareness, task performance, and overall image quality. However, no quantitative means to link image quality metrics with task performance exist for fused imaging, the way it does for single modality imaging. We illustrate how fused image quality is affected by multiple dimensions, including scene illumination, reflectance contrast, thermal

A. Waxman; D. Fay; P. Ilardi; D. Savoye; R. Biehl; D. Grau

2006-01-01

258

[Quality criteria for intra-oral roentgen images].  

PubMed

The apical and marginal parodontium are the main targets in dental roentgenology. The most important structural details are of 0.1 to 1.0 mm size. Their imaging is determined by - among other parameters - The X-ray film technique. This article presents quality criteria for a number of standard projections, that appear suitable for assessing the image quality. Other factors determining the characteristics of an x-ray film have been neglected, the only exception being a short treatise on the importance of contrast. PMID:2315636

Jung, T

1990-01-01

259

LANDSAT 4 image data quality analysis  

NASA Technical Reports Server (NTRS)

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

Anuta, P. E.

1983-01-01

260

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

261

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

PubMed Central

Introduction Quality chest compressions (CC) are the most important factor in successful cardiopulmonary resuscitation. Adjustment of CC based upon an invasive arterial blood pressure (ABP) display would be theoretically beneficial. Additionally, having one compressor present for longer than a 2-min cycle with an ABP display may allow for a learning process to further maximize CC. Accordingly, we tested the hypothesis that CC can be improved with a real-time display of invasively measured blood pressure and with an unchanged, physically fit compressor. Methods A manikin was attached to an ABP display derived from a hemodynamic model responding to parameters of CC rate, depth, and compression-decompression ratio. The area under the blood pressure curve over time (AUC) was used for data analysis. Each participant (N = 20) performed 4 CPR sessions: (1) No ABP display, exchange of compressor every 2 min; (2) ABP display, exchange of compressor every 2 min; (3) no ABP display, no exchange of the compressor; (4) ABP display, no exchange of the compressor. Data were analyzed by ANOVA. Significance was set at a p-value < 0.05. Results The average AUC for cycles without ABP display was 5201 mmHg s (95% confidence interval (CI) of 4804–5597 mmHg s), and for cycles with ABP display 6110 mmHg s (95% CI of 5715–6507 mmHg s) (p< 0.0001). The average AUC increase with ABP display for each participant was 20.2 ± 17.4% 95 CI (p < 0.0001). Conclusions Our study confirms the hypothesis that a real-time display of simulated ABP during CPR that responds to participant performance improves achieved and sustained ABP. However, without any real-time visual feedback, even fit compressors demonstrated degradation of CC quality. PMID:23816900

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

2014-01-01

262

Quality of Visual Experience for 3D Presentation - Stereoscopic Image  

Microsoft Academic Search

\\u000a Three-dimensional television (3DTV) technology is becoming increasingly popular, as it can provide high quality and immersive\\u000a experience to end users. Stereoscopic imaging is a technique capable of recoding 3D visual information or creating the illusion\\u000a of depth. Most 3D compression schemes are developed for stereoscopic images including applying traditional two-dimensional\\u000a (2D) compression techniques, and considering theories of binocular suppression as

Junyong You; Gangyi Jiang; Liyuan Xing; Andrew Perkis

263

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

264

Image quality prediction - An aid to the Viking lander imaging investigation on Mars  

NASA Technical Reports Server (NTRS)

Image quality criteria and image quality predictions are formulated for the multispectral panoramic cameras carried by the Viking Mars landers. Image quality predictions are based on expected camera performance, Mars surface radiance, and lighting and viewing geometry (fields of view, Mars lander shadows, solar day-night alternation), and are needed in diagnosis of camera performance, in arriving at a preflight imaging strategy, and revision of that strategy should the need arise. Landing considerations, camera control instructions, camera control logic, aspects of the imaging process (spectral response, spatial response, sensitivity), and likely problems are discussed. Major concerns include: degradation of camera response by isotope radiation, uncertainties in lighting and viewing geometry and in landing site local topography, contamination of camera window by dust abrasion, and initial errors in assigning camera dynamic ranges (gains and offsets).

Huck, F. O.; Wall, S. D.

1976-01-01

265

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

266

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. PMID:21448468

Jauregui Lobera, Ignacio; Bolanos Rios, Patricia

2011-01-01

267

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

PubMed

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

Owsley, N L; Hull, A J

1998-12-01

268

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

PubMed

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. PMID:24407501

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

2014-01-01

269

Image quality testing of assembled IR camera modules  

NASA Astrophysics Data System (ADS)

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

Winters, Daniel; Erichsen, Patrik

2013-10-01

270

Sharpness metric for no-reference image visual quality assessment  

NASA Astrophysics Data System (ADS)

This paper presents a novel sharpness metric for color images. The proposed metric can be used for no-reference assessment of image visual quality. The metric basically relies on local power of wavelet transform high-frequency coefficients. It also takes into account possibility of presence of macrophotography and portrait photography effects in an image where the image part (usually central one) in sharp whilst the remained part (background) is smeared. Such effects usually increase subjective evaluation of image visual quality by humans. The effects are taken into consideration by joint analysis of wavelet coefficients with largest and smallest squared absolute values. Besides, we propose a simple mechanism for blocking artifact accounting (if an image is compressed by JPEG) and compensation of this factor contribution. Finally, the proposed sharpness metric is calculated in color space YCbCr as a weighted sum of sharpness components. Weight optimization has shown that a weight for intensity component Y is to be considerably smaller than weights for color components Cb and Cr. Optimization of weights for all stages of sharpness metric calculation is carried out for specialized database NRTID that contains 500 test images with previously determined MOS (Mean Opinion Score). Spearman rank order correlation coefficient (SROCC) determined for the designed sharpness metric and MOS is used as optimization criterion. After optimization, it reaches 0.71. This is larger than for other known available no-reference metrics considered at verification stage.

Ponomarenko, Nikolay N.; Lukin, Vladimir V.; Eremeev, Oleg I.; Egiazarian, Karen O.; Astola, Jaakko T.

2012-03-01

271

Blind image quality assessment: from natural scene statistics to perceptual quality.  

PubMed

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 characterizing 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 an (NR)/blind algorithm-the Distortion Identification-based Image Verity and INtegrity Evaluation (DIIVINE) index-that assesses the quality of a distorted image without need for a reference image. DIIVINE is based on a 2-stage framework involving distortion identification followed by distortion-specific quality assessment. DIIVINE is capable of assessing the quality of a distorted image across multiple distortion categories, as against most NR IQA algorithms that are distortion-specific in nature. DIIVINE is based on natural scene statistics which govern the behavior of natural images. In this paper, we detail the principles underlying DIIVINE, the statistical features extracted and their relevance to perception and thoroughly evaluate the algorithm on the popular LIVE IQA database. Further, we compare the performance of DIIVINE against leading full-reference (FR) IQA algorithms and demonstrate that DIIVINE is statistically superior to the often used measure of peak signal-to-noise ratio (PSNR) and statistically equivalent to the popular structural similarity index (SSIM). A software release of DIIVINE has been made available online: "http://live.ece.utexas.edu/research/quality/DIIVINE_release.zip" xmlns:xlink="http://www.w3.org/1999/xlink">http://live.ece.utexas.edu/research/quality/DIIVINE_release.zip for public use and evaluation. PMID:21521667

Moorthy, Anush Krishna; Bovik, Alan Conrad

2011-12-01

272

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. PMID:24804177

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

2014-01-01

273

Color image encryption using a high-quality elemental image array  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

274

Decision theory applied to image quality control in radiology  

Microsoft Academic Search

BACKGROUND: The present work aims at the application of the decision theory to radiological image quality control (QC) in diagnostic routine. The main problem addressed in the framework of decision theory is to accept or reject a film lot of a radiology service. The probability of each decision of a determined set of variables was obtained from the selected films.

Patrícia S Lessa; Cristofer A Caous; Paula R Arantes; Edson Amaro; Fernando M Campello de Souza

2008-01-01

275

Comparison of retinal image quality with spherical and customized aspheric  

E-print Network

retinal image quality, despite the misalignments that accompany cataract surgery. To test this hypothesis power calculation after corneal refractive surgery: double-K method," J. Cataract Refract. Surg. 29 calculations after refractive surgery," J. Cataract Refract. Surg. 31(3), 562�570 (2005). 13. B. Seitz and A

Dainty, Chris

276

Perceptual evaluation of color night vision image quality  

Microsoft Academic Search

Color night vision techniques play a very important role in the night vision field. How to evaluate the perceptual quality of the color night vision image is a great need to assess the performance of algorithms in this technology. Currently, people usually judge the performance of color night vision techniques using subjective evaluation measures, which is time consuming and bothersome.

Shaoyuan Sun; Haitao Zhao

2007-01-01

277

A Perceptual Quality Metric for Performance Evaluation of Image Fusion  

Microsoft Academic Search

Usually, comparative evaluation by human visual inspection in image fusion is often used to assess the relative fusion performance of different fusion schemes. In this paper, a novel non-reference and quantitative quality metric is proposed to evaluate the performance of the fusion algorithms objectively. Instead of using traditional error summation methods, the proposed measure is designed to reflect humanpsilas visual

Muwei Jian; Ping Ma; Jianfeng Jia

2009-01-01

278

SCID: full reference spatial color image quality metric  

NASA Astrophysics Data System (ADS)

The most used full reference image quality assessments are error-based methods. Thus, these measures are performed by pixel based difference metrics like Delta E ( E), MSE, PSNR, etc. Therefore, a local fidelity of the color is defined. However, these metrics does not correlate well with the perceived image quality. Indeed, they omit the properties of the HVS. Thus, they cannot be a reliable predictor of the perceived visual quality. All this metrics compute the differences pixel to pixel. Therefore, a local fidelity of the color is defined. However, the human visual system is rather sensitive to a global quality. In this paper, we present a novel full reference color metric that is based on characteristics of the human visual system by considering the notion of adjacency. This metric called SCID for Spatial Color Image Difference, is more perceptually correlated than other color differences such as Delta E. The suggested full reference metric is generic and independent of image distortion type. It can be used in different application such as: compression, restoration, etc.

Ouni, S.; Chambah, M.; Herbin, M.; Zagrouba, E.

2009-01-01

279

Image-quality metrics for characterizing adaptive optics system performance  

Microsoft Academic Search

Adaptive optics system (AOS) performance is a function of the system design, seeing conditions, and light level of the wave-front beacon. It is desirable to optimize the controllable parameters in an AOS to maximize some measure of performance. For this optimization to be useful, it is necessary that a set of image-quality metrics be developed that vary monotonically with the

Robert T. Brigantic; Michael C. Roggemann; Kenneth W. Bauer; Byron M. Welsh

1997-01-01

280

A new approach for classification of fingerprint image quality  

Microsoft Academic Search

Fingerprint identification is a technology which has been widely accepted for personal identification in many areas such as criminal investigation, access control, and Internet authentication due to its uniqueness. Most available systems for fingerprint identification use the minutiae matching for identification. The performance of minutiae extraction algorithms relies heavily on the quality of the fingerprint image because the minutiae-based approach

Jun Wu; Shan Juan Xie; Dong-hun Seo; Won Don Lee

2008-01-01

281

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

282

The Value of Arterial Spin-Labeled Perfusion Imaging in Acute Ischemic Stroke - Comparison with Dynamic Susceptibility Contrast Enhanced MRI  

PubMed Central

Background and Purpose To evaluate the potential clinical value of arterial spin labeled (ASL) perfusion MRI in acute ischemic stroke (AIS) through comparison with dynamic susceptibility contrast (DSC) enhanced perfusion MRI. Methods Pseudo-continuous ASL with 3D background suppressed GRASE (Gradient and Spin Echo) readout was applied with DSC perfusion MRI on 26 AIS patients. ASL CBF and multi-parametric DSC perfusion maps were rated for image quality and lesion severity/conspicuity. Mean ASL CBF and DSC perfusion values were obtained in main vascular territories. Kendall’s coefficient of concordance was calculated to evaluate the reliability of ratings. Spearman correlation coefficients were calculated to compare ratings and quantitative perfusion values between ASL and DSC perfusion maps. Results ASL CBF and DSC perfusion maps provided largely consistent results in delineating hypoperfused brain regions in AIS. Hyperemic lesions, which also appeared frequently in the AIS cases studied, were more conspicuous on ASL CBF than on DSC CBF, Mean Transit Time (MTT) and Time to the maximum of the tissue residual function (Tmax) maps. Conclusions As a rapid, noninvasive and quantitative technique, ASL has clinical utility in detecting blood flow abnormalities in AIS patients. PMID:22328551

Wang, Danny JJ; Alger, Jeffry R; Qiao, Joe X; Hao, Qing; Hou, Samuel; Fiaz, Rana; Gunther, Matthias; Pope, Whitney B; Saver, Jeffrey L; Salamon, Noriko; Liebeskind, David S

2012-01-01

283

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

PubMed

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

Zurada, Anna; St Gielecki, Jerzy; Baron, Jan; Zawili?ski, Jaros?aw; Koz?owska, Hanna

2008-03-01

284

Diagnostic quality of low resolution images for tele-woundcare.  

PubMed

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. PMID:9929352

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

1998-01-01

285

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

286

Impact of Image Quality on Performance: Comparison of Young and Elderly Fingerprints  

Microsoft Academic Search

Performance of fingerprint recognition systems is heavily influenced by the quality of fingerprints provided by the user. Image quality analysis is traditionally performed using local and global structures of fingerprint images like ridge flow, analysis of ridge-valley structures, contrast ratios etc. With large scale deployment of fingerprint recognition in systems like US VISIT program, image quality issues of fingerprint images

Shimon K. Modi; Stephen J. Elliott

2006-01-01

287

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

288

Comprehensive quality assurance phantom for cardiovascular imaging systems  

NASA Astrophysics Data System (ADS)

With the advent of high heat loading capacity x-ray tubes, high frequency inverter type generators, and the use of spectral shaping filters, the automatic brightness/exposure control (ABC) circuit logic employed in the new generation of angiographic imaging equipment has been significantly reprogrammed. These new angiographic imaging systems are designed to take advantage of the power train capabilities to yield higher contrast images while maintaining, or lower, the patient exposure. Since the emphasis of the imaging system design has been significantly altered, the system performance parameters one is interested and the phantoms employed for the quality assurance must also change in order to properly evaluate the imaging capability of the cardiovascular imaging systems. A quality assurance (QA) phantom has been under development in this institution and was submitted to various interested organizations such as American Association of Physicists in Medicine (AAPM), Society for Cardiac Angiography & Interventions (SCA&I), and National Electrical Manufacturers Association (NEMA) for their review and input. At the same time, in an effort to establish a unified standard phantom design for the cardiac catheterization laboratories (CCL), SCA&I and NEMA have formed a joint work group in early 1997 to develop a suitable phantom. The initial QA phantom design has since been accepted to serve as the base phantom by the SCA&I- NEMA Joint Work Group (JWG) from which a comprehensive QA Phantom is being developed.

Lin, Pei-Jan P.

1998-07-01

289

Quality of DICOM header information for image categorization  

NASA Astrophysics Data System (ADS)

The widely used DICOM 3.0 imaging protocol specifies optional tags to store specific information on modality and body region within the header: Body Part Examined and Anatomic Structure. We investigate whether this information can be used for the automated categorization of medical images, as this is an important first step for medical image retrieval. Our survey examines the headers generated by four digital image modalities (2 CTs, 2 MRIs) in clinical routine at the Aachen University Hospital within a period of four months. The manufacturing dates of the modalities range from 1995 to 1999, with software revisions from 1999 and 2000. Only one modality sets the DICOM tag Body Part Examined. 90 out of 580 images (15.5%) contained false tag entries causing a wrong categorization. This result was verified during a second evaluation period of one month one year later (562 images, 15.3% error rate). The main reason is the dependency of the tag on the examination protocol of the modality, which controls all relevant parameters of the imaging process. In routine, the clinical personnel often applies an examination protocol outside its normal context to improve the imaging quality. This is, however, done without manually adjusting the categorization specific tag values. The values specified by DICOM for the tag Body Part Examined are insufficient to encode the anatomic region precisely. Thus, an automated categorization relying on DICOM tags alone is impossible.

Gueld, Mark O.; Kohnen, Michael; Keysers, Daniel; Schubert, Henning; Wein, Berthold B.; Bredno, Joerg; Lehmann, Thomas M.

2002-05-01

290

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. PMID:23164456

2012-01-01

291

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

SciTech Connect

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

Fujita, Norihiko; Sato, Tadayuki (Suita Municipal Hospital, Osaka (Japan)); Hirabuki, Norio; Fujii, Keiko; Hashimoto, Tsutomu; Miura, Takashi; Kozuka, Takahiro (Osaka Univ. Medical School (Japan))

1994-02-01

292

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

PubMed

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

Loizou, Christos P

2014-12-01

293

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

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

294

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

NASA Astrophysics Data System (ADS)

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

Mou, Xuanqin; Xue, Wufeng; Zhang, Lei

2012-03-01

295

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

Microsoft Academic Search

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

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

2008-01-01

296

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

PubMed

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

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

2014-01-01

297

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

E-print Network

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

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

2004-12-06

298

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

NASA Astrophysics Data System (ADS)

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

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

2000-04-01

299

No-reference image quality assessment in the spatial domain.  

PubMed

We propose a natural scene statistic-based distortion-generic blind/no-reference (NR) image quality assessment (IQA) model that operates in the spatial domain. The new model, dubbed blind/referenceless image spatial quality evaluator (BRISQUE) does not compute distortion-specific features, such as ringing, blur, or blocking, but instead uses scene statistics of locally normalized luminance coefficients to quantify possible losses of "naturalness" in the image due to the presence of distortions, thereby leading to a holistic measure of quality. The underlying features used derive from the empirical distribution of locally normalized luminances and products of locally normalized luminances under a spatial natural scene statistic model. No transformation to another coordinate frame (DCT, wavelet, etc.) is required, distinguishing it from prior NR IQA approaches. Despite its simplicity, we are able to show that BRISQUE is statistically better than the full-reference peak signal-to-noise ratio and the structural similarity index, and is highly competitive with respect to all present-day distortion-generic NR IQA algorithms. BRISQUE has very low computational complexity, making it well suited for real time applications. BRISQUE features may be used for distortion-identification as well. To illustrate a new practical application of BRISQUE, we describe how a nonblind image denoising algorithm can be augmented with BRISQUE in order to perform blind image denoising. Results show that BRISQUE augmentation leads to performance improvements over state-of-the-art methods. A software release of BRISQUE is available online: http://live.ece.utexas.edu/research/quality/BRISQUE_release.zip for public use and evaluation. PMID:22910118

Mittal, Anish; Moorthy, Anush Krishna; Bovik, Alan Conrad

2012-12-01

300

TL dosimetry for quality control of CR mammography imaging systems  

NASA Astrophysics Data System (ADS)

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

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

301

A multistage perceptual quality assessment for compressed digital angiogram images.  

PubMed

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 spatial frequency bands and orientations modeling the human cortex. Contrast errors are calculated for each frequency and orientation, and masked as a function of contrast sensitivity and background uncertainty. Spatially masked contrast error measurements are then made across frequency bands and orientations to produce a single perceptual distortion visibility map (PDVM). A perceptual quality rating (PQR) is calculated from the PDVM and transformed into a one to five scale, PQR(1-5), for direct comparison with the mean opinion score, generally used in subjective ratings. The proposed MPQA model is based on existing perceptual quality assessment models, while it is differentiated by the inclusion of contrast masking as a function of background uncertainty. A pilot study of clinical experiments on wavelet-compressed digital angiogram has been performed on a sample set of angiogram images to identify diagnostically acceptable reconstruction. Our results show that the PQR(1-5) of diagnostically acceptable lossy image reconstructions have better agreement with cardiologists' responses than objective error measurement methods, such as peak signal-to-noise ratio A Perceptual thresholding and CSF-based Uniform quantization (PCU) method is also proposed using the vision models presented in this paper. The vision models are implemented in the thresholding and quantization stages of a compression algorithm and shown to produce improved compression ratio performance with less visible distortion than that of the embedded zerotrees wavelet (EZWs). PMID:11811835

Oh, J; Woolley, S I; Arvanitis, T N; Townend, J N

2001-12-01

302

Imaging and Clinical Findings in Patients with Aberrant Course of the Cervical Internal Carotid Arteries  

PubMed Central

Background and Purpose: Aberrrant course of the cervical internal carotid arteries (ICAs) may result in submucosal masses in the posterior pharyngeal wall, may cause confusion at physical examination, may be symptomatic, and can be at risk of surgical injury. The aim of this report is to present the clinical and imaging characteristics associated with aberrant course of the cervical portion of the ICAs. Methods: Imaging studies of 5.500 patients were prospectively selected from CT studies of the head and neck performed in a five years period, in which the course of the one or both ICAs at the level of the hypopharynx and oropharynx was assessed as aberrant by means of a proposed classification. We then reviewed the medical records to establish which symptoms were present and if these symptoms could be caused by these variations in the course of the ICAs. In selected cases, further studies including magnetic resonance (MR) imaging, MR angiography (MRA), or selective catheter angiography were obtained. Results: In our restricted classification, we found 14 (0.2%) patients who met the cervical ICA aberrancy criteria. In all patients contrast enhanced CT or CT angiography was performed, 4 also have had MRI and MRA, and in two additional catheter angiograms were performed. Mean age was 62 years. Eight patients were male and seven were female. Four patients (28%) were considered to have clinical symptoms related to aberrant course of the ICAs. In most of the symptomatic patients both ICAs had aberrant courses. Overall, the course of the right ICA was aberrant in 43%, the left ICA in 14%, and both in 43%. In 50% of the cases the aberrancy of the artery was focal (localized to the oropharynx or laryngopharynx) and in the other 50% it involved the entire cervical course of the ICA. Conclusions: In most of our patients variations in the course of the cervical portion of the ICA involved the right side and were asymptomatic, except with regard to potential surgical risks. However, in about 25% of our patients these variations were thought to be the culprit of patient complaints, particularly oropharyngeal pulsatile sensation. Furthermore, extreme degrees of medialization of the ICAs resulted in progressive symptoms including hoarseness and upper respiratory distress. PMID:21283647

Munoz, Alberto; De Vergas, Joaquin; Crespo, Jose

2010-01-01

303

Correction for Arterial-Tissue Delay and Dispersion in Absolute Quantitative Cerebral Perfusion DSC MR Imaging  

PubMed Central

The singular value decomposition deconvolution of cerebral tissue concentration-time (C-T) curves with the arterial input function (AIF) is commonly used in dynamic susceptibility contrast (DSC) cerebral perfusion MR imaging. However, it is sensitive to the time discrepancy between the arrival of the bolus in the tissue C-T curve and the AIF signal. This normally causes inaccuracy in the quantitative perfusion maps due to delay and dispersion effects. A comprehensive correction algorithm has been achieved through slice-dependent time-shifting of the AIF, and a delay-dependent dispersion correction model. The correction algorithm was tested in 11 healthy subjects and 3 ischemic stroke patients scanned with a quantitative perfusion pulse sequence at 1.5T. A validation study was performed on 5 patients with confirmed cerebrovascular occlusive disease scanned with MRI and positron emission tomography (PET) at 3.0T. A significant effect (p<0.05) was reported on the quantitative cerebral blood flow and mean transit time measurements (up to 50%). There was no statistically significant effect on the quantitative cerebral blood volume values. The in vivo results were in agreement with the simulation results, as well as previous literature. This minimizes the bias in patient diagnosis due to the existing errors and artifacts in DSC imaging. PMID:22162092

Mouannes-Srour, Jessy J.; Shin, Wanyong; Ansari, Sameer A.; Hurley, Michael C.; Vakil, Parmede; Bendok, Bernard R.; Lee, John L.; Derdeyn, Colin P.; Carroll, Timothy J.

2011-01-01

304

Coronary arteries motion modeling on 2D x-ray images  

NASA Astrophysics Data System (ADS)

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

Gao, Yang; Sundar, Hari

2012-02-01

305

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

SciTech Connect

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

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

2007-09-15

306

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

NASA Astrophysics Data System (ADS)

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

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

2010-01-01

307

Optimizing 3D image quality and performance for stereoscopic gaming  

NASA Astrophysics Data System (ADS)

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

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

2009-02-01

308

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

NASA Astrophysics Data System (ADS)

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

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

2001-08-01

309

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. PMID:24804036

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

2013-01-01

310

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

311

An educational hypertext system supporting radiographic image quality.  

PubMed

Understanding the physical and technical factors affecting image characteristics is an essential learning task in the process of optimizing radiographic image quality. The goal of the present effort is the design of a stand-alone software application acting as an educational aid to radiology residents and radiographers. The application is organized in three modules, each one offering a different approach to the learning task. The core of the system is a hypertext database management system composed of text, digitized radiographs, graphics and animations. User orientation, linking, indexing, and annotation are some of the facilities offered in pursuing topics of interest. PMID:8072341

Costaridou, L; Sphiris, N; Pitoura, T; Panayiotakis, G; Pallikarakis, N

1993-01-01

312

Spectral CT Imaging in Patients with Budd-Chiari Syndrome: Investigation of Image Quality.  

PubMed

To assess the image quality of monochromatic imaging from spectral CT in patients with Budd-Chiari syndrome (BCS), fifty patients with BCS underwent spectral CT to generate conventional 140 kVp polychromatic images (group A) and monochromatic images, with energy levels from 40 to 80, 40 + 70, and 50 + 70 keV fusion images (group B) during the portal venous phase (PVP) and the hepatic venous phase (HVP). Two-sample t tests compared vessel-to-liver contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) for the portal vein (PV), hepatic vein (HV), inferior vena cava. Readers' subjective evaluations of the image quality were recorded. The highest SNR values in group B were distributed at 50 keV; the highest CNR values in group B were distributed at 40 keV. The higher CNR values and SNR values were obtained though PVP of PV (SNR 18.39 ± 6.13 vs. 10.56 ± 3.31, CNR 7.81 ± 3.40 vs. 3.58 ± 1.31) and HVP of HV (3.89 ± 2.08 vs. 1.27 ± 1.55) in the group B; the lower image noise for group B was at 70 keV and 50 + 70 keV (15.54 ± 8.39 vs. 18.40 ± 4.97, P = 0.0004 and 18.97 ± 7.61 vs. 18.40 ± 4.97, P = 0.0691); the results show that the 50 + 70 keV fusion image quality was better than that in group A. Monochromatic energy levels of 40-70, 40 + 70, and 50 + 70 keV fusion image can increase vascular contrast and that will be helpful for the diagnosis of BCS, we select the 50 + 70 keV fusion image to acquire the best BCS images. PMID:24833430

Su, Lei; Dong, Junqiang; Sun, Qiang; Liu, Jie; Lv, Peijie; Hu, Lili; Yan, Liangliang; Gao, Jianbo

2014-11-01

313

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

2012-06-01

314

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

315

The impact of temporal inaccuracies on 4DCT image quality  

SciTech Connect

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

Mutaf, Y. D.; Antolak, J. A.; Brinkmann, D. H. [Radiation Oncology Department, Mayo Clinic, 200 1st Street SW. Rochester, Minnesota 55905 (United States)

2007-05-15

316

Coronary artery calcium quantification from contrast enhanced CT using gemstone spectral imaging and material decomposition.  

PubMed

To explore the feasibility of coronary artery calcium (CAC) measurement from low-dose contrast enhanced coronary CT angiography (CCTA) as this may obviate the need for an unenhanced CT scan. 52 patients underwent unenhanced cardiac CT and prospectively ECG triggered contrast enhanced CCTA (Discovery HD 750, GE Healthcare, Milwaukee, WI, USA). The latter was acquired in single-source dual-energy mode [gemstone spectral imaging (GSI)]. Virtual unenhanced images were generated from GSI CCTA by monochromatic image reconstruction of 70 keV allowing selective iodine material suppression. CAC scores from virtual unenhanced CT were compared to standard unenhanced CT including a linear regression model. After iodine subtraction from the contrast enhanced CCTA the attenuation in the ascending aorta decreased significantly from 359 ± 61 to 54 ± 8 HU (P < 0.001), the latter comparing well to the value of 64 ± 55 HU found in the standard unenhanced CT (P = ns) confirming successful iodine subtraction. After introducing linear regression formula the mean values for Agatston, Volume and Mass scores of virtual unenhanced CT were 187 ± 321, 72 ± 114 mm(3), and 27 ± 46 mg/cm(3), comparing well to the values from standard unenhanced CT (187 ± 309, 72 ± 110 mm(3), and 27 ± 45 mg/cm(3)) yielding an excellent correlation (r = 0.96, r = 0.96, r = 0.92; P < 0.001). Mean estimated radiation dose revealed 0.83 ± 0.02 mSv from the unenhanced CT and 1.70 ± 0.53 mSv from the contrast enhanced CCTA. Single-source dual-energy scanning with GSI allows CAC quantification from low dose contrast enhanced CCTA by virtual iodine contrast subtraction. PMID:24993390

Fuchs, Tobias A; Stehli, Julia; Dougoud, Svetlana; Sah, Bert-Ram; Bull, Sacha; Clerc, Olivier F; Possner, Mathias; Buechel, Ronny R; Gaemperli, Oliver; Kaufmann, Philipp A

2014-10-01

317

Evaluation of scatter effects on image quality for breast tomosynthesis  

Microsoft Academic Search

Digital breast tomosynthesis uses a limited number of low-dose x-ray projections to produce a three-dimensional (3D) tomographic reconstruction of the breast. The purpose of this investigation was to characterize and evaluate the effect of scatter radiation on image quality for breast tomosynthesis. Generated by a Monte Carlo simulation method, scatter point spread functions (PSF) were convolved over the field of

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

2007-01-01

318

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

SciTech Connect

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

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

1980-05-01

319

Automated image analysis for diameters and branching points of cerebral penetrating arteries and veins captured with two-photon microscopy.  

PubMed

The present study was aimed to characterize 3-dimensional (3D) morphology of the cortical microvasculature (e.g., penetrating artery and emerging vein), using two-photon microscopy and automated analysis for their cross-sectional diameters and branching positions in the mouse cortex. We observed that both artery and vein had variable cross-sectional diameters across cortical depths. The mean diameter was similar for both artery (17 ± 5 ?m) and vein (15 ± 5 ?m), and there were no detectable differences over depths of 50-400 ?m. On the other hand, the number of branches was slightly increased up to 400-?m depth for both the artery and vein. The mean number of branches per 0.1 mm vessel length was 1.7 ± 1.2 and 3.8 ± 1.6 for the artery and vein, respectively. This method allows for quantification of the large volume data of microvascular images captured with two-photon microscopy. This will contribute to the morphometric analysis of the cortical microvasculature in functioning brains. PMID:24729235

Sugashi, Takuma; Yoshihara, Kouichi; Kawaguchi, Hiroshi; Takuwa, Hiroyuki; Ito, Hiroshi; Kanno, Iwao; Yamada, Yukio; Masamoto, Kazuto

2014-01-01

320

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

321

Image Processing Workstations And Data Bases For Quality Control Of Geocoded Satellite Images  

Microsoft Academic Search

,1. Abstract In the framework of processing facilities for future earth remote sensing sensors (ERS-l, SIR-C\\/X-SAR), the geocoding of Synthetic Aperture Radar images becomes an important aspect for supporting user data needs. DLR will offer such images, tackling with a wide range of process­ ing and cartographic parameters. As geocoding claims for comparability with topographic references, the geometric quality control

G. Schreier

1989-01-01

322

Effects of characteristics of image quality in an immersive environment  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

323

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. PMID:25053898

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

2014-01-01

324

Coronary Vessel Wall 3-T MR Imaging with Time-resolved Acquisition of Phase-Sensitive Dual Inversion-Recovery (TRAPD) Technique: Initial Results in Patients with Risk Factors for Coronary Artery Disease  

PubMed Central

Purpose: To develop a technique for time-resolved acquisition of phase-sensitive dual-inversion recovery (TRAPD) coronary vessel wall magnetic resonance (MR) images, to investigate the success rate in coronary wall imaging compared with that of single-frame imaging, and to assess vessel wall thickness in healthy subjects and subjects with risk factors for coronary artery disease (CAD). Materials and Methods: Thirty-eight subjects (12 healthy subjects, 26 subjects with at least one CAD risk factor) provided informed consent for participation in this institutional review board–approved and HIPAA-compliant study. The TRAPD coronary vessel wall imaging sequence was developed and validated with a flow phantom. Time-resolved coronary artery wall images at three to five cine phases were obtained in all subjects. Qualitative and quantitative comparisons were made between TRAPD and conventional single-image wall measurements. Measurement reproducibility also was assessed. Statistical analysis was performed for all comparisons. Results: The TRAPD sequence successfully restored the negative polarity of lumen signal and enhanced lumen wall contrast on the cine images of the flow phantom and in all subjects. Use of three to five frames increased the success rate of acquiring at least one image of good to excellent quality from 76% in single-image acquisitions to 95% with the TRAPD sequence. The difference in vessel wall thickness between healthy subjects and subjects with CAD risk factors was significant (P < .05) with the TRAPD sequence (1.07 vs 1.46 mm, respectively; 36% increase) compared with single-frame dual inversion-recovery imaging (1.24 vs 1.55 mm, respectively; 25% increase). Intraobserver, interobserver, and interexamination agreement for wall thickness measurement were 0.98, 0.97, and 0.92, respectively. Conclusion: TRAPD imaging of coronary arteries improved arterial wall visualization and quantitative assessment by increasing the success rate of obtaining good- to excellent-quality images and sections orthogonal to the longitudinal axis of the vessel. This also resulted in vessel wall thickness measurements that show a more distinct difference between healthy subjects and those with CAD risk factors. © RSNA, 2012 Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12120068/-/DC1 PMID:23047838

Gharib, Ahmed M.; Pettigrew, Roderic I.

2012-01-01

325

Gender Modifies the Effects of Education and Income on Sleep Quality of the Patients with Coronary Artery Disease  

PubMed Central

Background: This study aimed to investigate the interaction between gender and other socio-economic characteristics on sleep quality of the patients with Coronary Artery Disease (CAD). Methods: This cross sectional study was conducted on 717 patients with CAD. The socio- economic status (education level, income, marital status, and place of residence) was considered as the independent variable. Besides, the study outcome was the quality of sleep which was measured using Pittsburgh Sleep Quality Index (PSQI). Gender was considered as a possible effect modifier. Two-way ANOVA was used to evaluate the interaction between gender and socio-economic factors on sleep quality. As defined by Baron and Kenny, moderator was defined as a variable that affected the direction or magnitude of the association of interest. Results: Female gender, low education level, and low income were predictive of poor sleep quality. Among female (10.0 ± 4.3 vs. 7.6 ± 5.0, P < 0.05), but not male patients (6.7 ± 4.2 vs. 7.0 ± 4.2, P > 0.05), low education was associated with poor sleep quality. Also, among female (10.0 ± 4.3 vs. 5.7 ± 2.5, P < 0.05), but not male patients (7.0 ± 4.2 vs. 6.0 ± 3.8, P > 0.05), low income was predictive of poor sleep quality. Gender did not modify the effect of other socio-economic factors on sleep quality. Conclusions: Among female but not male patients with CAD, low education and income were associated with poor sleep quality. This information helps us better understand the mechanisms behind the poor sleep quality of the female patients with CAD. This is important because poor sleep is a prognostic factor among the CAD patients. PMID:24757639

Assari, Shervin; Moghani Lankarani, Maryam; Kazemi Saleh, Davoud; Ahmadi, Khodabakhsh

2013-01-01

326

Evaluation of scatter effects on image quality for breast tomosynthesis.  

PubMed

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

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

2009-10-01

327

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

328

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

PubMed Central

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

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

2013-01-01

329

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

330

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. PMID:23508852

Yang, Na; Demirkol, Ilker; Heinzelman, Wendi

2013-01-01

331

Objective quality assessment of color images based on a generic perceptual reduced reference  

Microsoft Academic Search

W}hen an image is supposed to have been transformed by a process like image enhancement or lossy image compression for storing or transmission, it is often necessary to measure the quality of the distorted image. {T}his can be achieved using an image processing method called “quality criterion”. {S}uch a process must produce objective quality scores in close relationship with subjective

Mathieu Carnec; Patrick Le Callet; Dominique Barba

2008-01-01

332

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

333

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. PMID:20849317

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

2010-01-01

334

Construction of a physical model of the human carotid artery based upon in vivo magnetic resonance images.  

PubMed

A method is described for construction of an in vitro flow model based on in vivo measurements of the lumen geometry of the human carotid bifurcation. A large-scale physical model of the vessel lumen was constructed using fused deposition modeling (a rapid prototyping technique) based on magnetic resonance (MR) images of the carotid bifurcation acquired in a healthy volunteer. The lumen negative was then used to construct a flow model for experimental studies that examined the hemodynamic environment of subject-specific geometry and flow conditions. The physical model also supplements physician insight into the three-dimensional geometry of the arterial segment, complementing the two-dimensional images obtained by MR. Study of the specific geometry and flow conditions in patients with vascular disease may contribute to our understanding of the relationship between their hemodvnamic environment and conditions that lead to the development and progression of arterial disease. PMID:11563764

Yedavalli, R V; Loth, F; Yardimci, A; Pritchard, W F; Oshinski, J N; Sadler, L; Charbel, F; Alperin, N

2001-08-01

335

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

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

336

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

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

337

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

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

338

Blood Oxygen Level Dependent Magnetic Resonance Imaging (BOLD MRI) analysis in Atherosclerotic Renal Artery Stenosis  

PubMed Central

Purpose of review Blood Oxygen Level Dependent Magnetic Resonance Imaging (BOLD MRI) is a noninvasive tehnique evaluating kidney tissue oxygenation that requires no contrast exposure with the potential to allow functional assessment for patients with Atherosclerotic Renal Artery Stenosis (ARAS). Normal cortical-to-medulla oxygenation gradients are preserved in many patients treated for several years with medical antihypertensive therapy without restoring renal blood flow. The current review is of particular interest as new methods were applied to the analyses of BOLD MRI opening perspective of its wider utilization in the clinical practice. Recent findings Recent findings show that more severe vascular compromise ultimately overwhelms these adaptive changes, leading to overt cortical hypoxia and expansion of medullary hypoxic zones. “Fractional kidney hypoxia” method of analysis, developed as an alternative method of BOLD MRI analysis, avoids the assumption of discrete cortical and medullary values and decreases the bias related to operator selection of ROIs. Summary We believe that thoughtful application and analysis of BOLD MRI can provide critical insights into changes in renal function prior to the onset of irreversible renal injury and may identify patients most likely to gain from measures to reverse or repair disorders of tissue oxygenation. PMID:23917027

Gloviczki, Monika L.; Saad, Ahmed; Textor, Stephen C.

2014-01-01

339

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

SciTech Connect

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

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

1986-01-01

340

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

PubMed Central

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

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

2014-01-01

341

Rate Allocation of Equal Image Quality for MPEG4 FGS Video Streaming  

Microsoft Academic Search

This paper proposes a new rate allocation method for MPEG-4 fine granularity scalable (FGS) video streaming, with which the received image quality can be smoothed during the streaming period. Although average bit rate allocation is quite simple, the image's quality changes greatly between frames, which will result in quality fluctuation and degrade the streaming quality. In this paper the bits

Xuejun Zhao; Yuwen He; Shiqiang Yang; Yuzhuo Zhong

2002-01-01

342

A Statistical Evaluation of Recent Full Reference Image Quality Assessment Algorithms  

Microsoft Academic Search

Measurement of visual quality is of fundamental importance for numerous image and video pro- cessing applications, where the goal of quality assessment (QA) algorithms is to automatically assess the quality of images or videos in agreement with human quality judgments. Over the years, many researchers have taken different approaches to the problem and have contributed significant research in this area,

Hamid Rahim Sheikh; Muhammad Farooq Sabir; Alan Conrad Bovik

2006-01-01

343

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

Microsoft Academic Search

In this paper the effect of uterine artery embolization (UAE) on sexual functioning and body image is investigated in a randomized\\u000a comparison to hysterectomy for symptomatic uterine fibroids. The EMbolization versus hysterectoMY (EMMY) trial is a randomized\\u000a controlled study, conducted at 28 Dutch hospitals. Patients were allocated hysterectomy (n = 89) or UAE (n = 88). Two validated questionnaires (the

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

2007-01-01

344

Feasibility of real time dual-energy imaging based on a flat panel detector for coronary artery calcium quantification  

Microsoft Academic Search

The feasibility of a real-time dual-energy imaging technique with dynamic filtration using a flat panel detector for quantifying coronary arterial calcium was evaluated. In this technique, the x-ray beam was switched at 15 Hz between 60 kVp and 120 kVp with the 120 kVp beam having an additional 0.8 mm silver filter. The performance of the dynamic filtration technique was

Tong Xu; Justin L. Ducote; Jerry T. Wong; Sabee Molloi

2006-01-01

345

Intracoronary Doppler assessment of moderate coronary artery disease: comparison with 201Tl imaging and coronary angiography. FACTS Study Group  

Microsoft Academic Search

BACKGROUND: Coronary angiography may not reliably predict whether a stenosis causes exercise-induced ischemia. Intracoronary Doppler ultrasound may enhance diagnostic accuracy by providing a physiological assessment of stenosis severity. The goal of this study was to compare intracoronary Doppler ultrasound with both 201Tl imaging and coronary angiography.\\u000aMETHODS AND RESULTS: Fifty-five patients with 67 stenotic coronary arteries underwent coronary angiography with

Louis I. Heller; Christopher Cates; Jeffrey Popma; Lawrence I. Deckelbaum; James D. Joye; Seth T. Dahlberg; Bernard J. Villegas; Anita Arnold; Robert Kipperman; W. Carter Grinstead; Sharon Balcom; Yunsheng Ma; Michael Cleman; Richard M. Steingart; Jeffrey A. Leppo

1997-01-01

346

Channelling optics for high quality imaging of sensory hair.  

PubMed

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 mm(2) 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). PMID:22559565

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

2012-04-01

347

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

SciTech Connect

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

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

2009-12-15

348

Demonstration of correlations between physical and clinical image quality measures in chest and lumbar spine radiography  

Microsoft Academic Search

Clinical and physical assessments of image quality are compared and the correlation between the two derived. Clinical assessment has been made by a group of expert radiologists who evaluated the fulfillment of the European Image Criteria for chest and lumbar spine radiography; yielding the so-called Image Criteria Score, ICS. Physical measures of image quality were calculated using a Monte Carlo

Michael Sandborg; Anders Tingberg; Patrik Sund; Graham McVey; David Dance; Gudrun Alm Carlsson

2000-01-01

349

ASSESSING THE QUALITY OF COMPRESSED IMAGES USING EEG Lea Lindemann, Marcus Magnor  

E-print Network

Lab, TU Braunschweig, Germany ABSTRACT The way images are perceived by a human observer is becoming image quality degradation. As a first step to find out if the assessment of image qua- lity with EEG and depth of field [7]. There has not been much research regarding the evalua- tion of image quality using

Magnor, Marcus

350

Image quality in optical imaging by time-correlated single photon-counting technique  

NASA Astrophysics Data System (ADS)

Theoretical and experimental investigations on image quality are extremely important in optical imaging in order to better define the role of optical techniques in medical diagnostics. Today time-resolved laser transillumination can be considered a good candidate as an alternative and/or auxiliary technique in medical diagnostic field. The intrinsic quality of an image is related to the concepts of spatial resolution, noise and contrast. A common method to measure these parameters is by using Edge Response Function measurements with a black mask. We investigated these parameters using an experimental apparatus mainly composed by a picosecond solid-state laser and a time-correlated single photon-counting system. The investigated samples were suspensions of Intralipid 10% with distilled water in which a black mask was inserted and bidimensional scanning were performed. The experimental data were analyzed in order to get information on the above-mentioned image quality parameters. For spatial resolution a comparison with random walk predictions has been attempted. The results of this study can be particularly useful in identifying the best working conditions and in improving teh performance of image reconstruction algorithms since the clinical prototypes of optical mammogrpahers nowadays under pre-clinical investigation adopt time-correlated single photon-counting technique.

Mormile, M.; Esposito, R.; Romano, R.; Lepore, M.; Indovina, P. L.

2005-06-01

351

Image quality evaluation of breast tomosynthesis with synchrotron radiation  

SciTech Connect

Purpose: This study investigates the image quality of tomosynthesis slices obtained from several acquisition sets with synchrotron radiation using a breast phantom incorporating details that mimic various breast lesions, in a heterogeneous background. Methods: A complex Breast phantom (MAMMAX) with a heterogeneous background and thickness that corresponds to 4.5 cm compressed breast with an average composition of 50% adipose and 50% glandular tissue was assembled using two commercial phantoms. Projection images using acquisition arcs of 24 Degree-Sign , 32 Degree-Sign , 40 Degree-Sign , 48 Degree-Sign , and 56 Degree-Sign at incident energy of 17 keV were obtained from the phantom with the synchrotron radiation for medical physics beamline at ELETTRA Synchrotron Light Laboratory. The total mean glandular dose was set equal to 2.5 mGy. Tomograms were reconstructed with simple multiple projection algorithm (MPA) and filtered MPA. In the latter case, a median filter, a sinc filter, and a combination of those two filters were applied on the experimental data prior to MPA reconstruction. Visual inspection, contrast to noise ratio, contrast, and artifact spread function were the figures of merit used in the evaluation of the visualisation and detection of low- and high-contrast breast features, as a function of the reconstruction algorithm and acquisition arc. To study the benefits of using monochromatic beams, single projection images at incident energies ranging from 14 to 27 keV were acquired with the same phantom and weighted to synthesize polychromatic images at a typical incident x-ray spectrum with W target. Results: Filters were optimised to reconstruct features with different attenuation characteristics and dimensions. In the case of 6 mm low-contrast details, improved visual appearance as well as higher contrast to noise ratio and contrast values were observed for the two filtered MPA algorithms that exploit the sinc filter. These features are better visualized at extended arc length, as the acquisition arc of 56 Degree-Sign with 15 projection images demonstrates the highest image reconstruction quality. For microcalcifications, filtered MPA implemented with a combination of median and sinc filters indicates better feature appearance due to efficient suppression of background tissue. The image quality of these features is less sensitive to the acquisition arc. Calcifications with size ranging from 170 to 500 {mu}m, like the ones presently studied, are well identified and visualized for all arcs used. The comparison of single projection images obtained under different beam conditions showed that the use of monochromatic beam can produce an image with higher contrast and contrast to noise ratio compared to an image corresponding to a polychromatic beam even when the latter is acquired with double incident exposure. Conclusions: Filter optimization in respect to the type of feature characteristics is important before the reconstruction. The MPA combined with median and sinc filters results in improved reconstruction of microcalcifications and low-contrast features. The latter are better visualized at extended arc length, while microcalcifications are less sensitive to this acquisition parameter. Use of monochromatic beams may result in tomographic images with higher contrast acquired at lower incident exposures.

Malliori, A.; Bliznakova, K.; Speller, R. D.; Horrocks, J. A.; Rigon, L.; Tromba, G.; Pallikarakis, N. [Department of Medical Physics, Faculty of Medicine, University of Patras, Patras 26500 (Greece); Department of Medical Physics and Bioengineering, University College London, London WVC1E 6BT (United Kingdom); Clinical Physics CAU, St Bartholomew's Hospital, London EC1A 7BE (United Kingdom); INFN, Sezione di Trieste, Trieste 34127 (Italy); ELETTRA, Basovizza, Trieste 34012 (Italy); Department of Medical Physics, Faculty of Medicine, University of Patras, Patras 26500 (Greece)

2012-09-15

352

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

NASA Astrophysics Data System (ADS)

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

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

2011-08-01

353

Image quality of a cone beam O-arm 3D imaging system  

NASA Astrophysics Data System (ADS)

The O-arm is a cone beam imaging system designed primarily to support orthopedic surgery and is also used for image-guided and vascular surgery. Using a gantry that can be opened or closed, the O-arm can function as a 2-dimensional (2D) fluoroscopy device or collect 3-dimensional (3D) volumetric imaging data like a CT system. Clinical applications of the O-arm in spine surgical procedures, assessment of pedicle screw position, and kyphoplasty procedures show that the O-arm 3D mode provides enhanced imaging information compared to radiographs or fluoroscopy alone. In this study, the image quality of an O-arm system was quantitatively evaluated. A 20 cm diameter CATPHAN 424 phantom was scanned using the pre-programmed head protocols: small/medium (120 kVp, 100 mAs), large (120 kVp, 128 mAs), and extra-large (120 kVp, 160 mAs) in 3D mode. High resolution reconstruction mode (512×512×0.83 mm) was used to reconstruct images for the analysis of low and high contrast resolution, and noise power spectrum. MTF was measured using the point spread function. The results show that the O-arm image is uniform but with a noise pattern which cannot be removed by simply increasing the mAs. The high contrast resolution of the O-arm system was approximately 9 lp/cm. The system has a 10% MTF at 0.45 mm. The low-contrast resolution cannot be decided due to the noise pattern. For surgery where locations of a structure are emphasized over a survey of all image details, the image quality of the O-arm is well accepted clinically.

Zhang, Jie; Weir, Victor; Lin, Jingying; Hsiung, Hsiang; Ritenour, E. Russell

2009-02-01

354

Needle-shape quality control by shadowgraphic image processing  

NASA Astrophysics Data System (ADS)

We propose a needle-shape quality-control method. To this end, we have devised a new acquisition system that combines a camera and a backlight. Needle measurements are carried out at a micrometric scale using shadowgraphic image processing. Our method not only distinguishes good needles from bad ones, but also allows classifying flawed needles into various categories of defects. This classification is important because some categories of defects can affect the entire production, whereas others do not. The results of our needle-shape quality-control method are validated using real samples directly off the manufacturing line. Needles are correctly classified at >97%, and accurate measurements on global shape characteristics such as straightness and sharpness are obtained.

Mairesse, Fabrice; Sliwa, Tadeusz M.; Roy, Michaël; Voisin, Yvon

2011-02-01

355

The effect of ambient illumination on handheld display image quality.  

PubMed

Handheld devices such as smartphones and tablets are becoming useful in the medical field, as they allow physicians, radiologists, and researchers to analyze images with the benefit of mobile accessibility. However, for handheld devices to be effective, the display must be able to perform well in a wide range of ambient illumination conditions. We conducted visual experiments to quantify user performance for testing the image quality of two current-generation devices in different ambient illumination conditions while measuring ambient light levels with a real-time illuminance meter. We found and quantified that due to the high reflectivity of handheld devices, performance deteriorates as the user moves from dark areas into environments of greater ambient illumination. The quantitative analysis suggests that differences in display reflection coefficients do not affect the low illumination performance of the device but rather the performance at higher levels of illumination. PMID:24113844

Liu, Peter; Zafar, Fahad; Badano, Aldo

2014-02-01

356

Impact of chopping on image quality in the SIRTF telescope  

NASA Technical Reports Server (NTRS)

The initial Phase-A concept for the Space Infrared Telescope Facility (SIRTF), which was established in 1981, is concerned with a cryogenically cooled, 85 cm diameter, f/24 Ritchey-Chretien telescope, followed by a Multiple Instrument Chamber (MIC), containing six scientific instruments. In 1982, the Phase-A concept was reviewed with the aim to assess the technical readiness for the next phase of development. Various areas of concern were subsequently investigated in three parallel studies by industry. Two of the arising questions are considered in the present paper, taking into account the system and technology implications of achieving diffraction-limited resolution at 2 microns, and the limitations on the size of the imaging field under this condition. The conducted study takes into account an evaluation of the different methods of chopping. Attention is given to the telescope parameters, symmetric chopping, asymmetrical chopping, focus and alignment errors, the wavefront-error budget, and image quality.

Bottema, M.

1985-01-01

357

An accurate iris location method for low quality iris images  

NASA Astrophysics Data System (ADS)

Iris location plays an important role in iris recognition system. Traditional iris location methods based on canny operator and integro-differential operator are affected by reflections, illumination inconsistency and eyelash. In this paper, we introduce an accurate iris location method for low quality iris images. First, a reflection removal method is used to interpolate the specular reflection. Then, we utilize Probable boundary (Pb) edge detection operator to detect papillary boundary with a lower interference point. Moreover, we optimize the Hough transform to obtain high accuracy result. Experimental results demonstrate that the location results of the proposed method are more accurate than other methods.

Wang, Ning; Li, Qiong; Abd El-Latif, Ahmed A.; Zhang, Tiejun; Peng, Jialiang

2012-04-01

358

Influence of void on image quality of industrial SPECT  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

359

An automated system for numerically rating document image quality  

SciTech Connect

As part of the Department of Energy document declassification program, the authors have developed a numerical rating system to predict the OCR error rate that they expect to encounter when processing a particular document. The rating algorithm produces a vector containing scores for different document image attributes such as speckle and touching characters. The OCR error rate for a document is computed from a weighted sum of the elements of the corresponding quality vector. The predicted OCR error rate will be used to screen documents that would not be handled properly with existing document processing products.

Cannon, M.; Kelly, P. [Los Alamos National Lab., NM (United States); Iyengar, S.S.; Brener, N. [Louisiana State Univ., Baton Rouge, LA (United States)

1997-04-01

360

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

SciTech Connect

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

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

1987-02-01

361

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

362

Virtual monochromatic imaging in dual-source dual-energy CT: Radiation dose and image quality  

SciTech Connect

Purpose: To evaluate the image quality of virtual monochromatic images synthesized from dual-source dual-energy computed tomography (CT) in comparison with conventional polychromatic single-energy CT for the same radiation dose. Methods: In dual-energy CT, besides the material-specific information, one may also synthesize monochromatic images at different energies, which can be used for routine diagnosis similar to conventional polychromatic single-energy images. In this work, the authors assessed whether virtual monochromatic images generated from dual-source CT scanners had an image quality similar to that of polychromatic single-energy images for the same radiation dose. First, the authors provided a theoretical analysis of the optimal monochromatic energy for either the minimum noise level or the highest iodine contrast to noise ratio (CNR) for a given patient size and dose partitioning between the low- and high-energy scans. Second, the authors performed an experimental study on a dual-source CT scanner to evaluate the noise and iodine CNR in monochromatic images. A thoracic phantom with three sizes of attenuating rings was used to represent four adult sizes. For each phantom size, three dose partitionings between the low-energy (80 kV) and the high-energy (140 kV) scans were used in the dual-energy scan. Monochromatic images at eight energies (40 to 110 keV) were generated for each scan. Phantoms were also scanned at each of the four polychromatic single energy (80, 100, 120, and 140 kV) with the same radiation dose. Results: The optimal virtual monochromatic energy depends on several factors: phantom size, partitioning of the radiation dose between low- and high-energy scans, and the image quality metrics to be optimized. With the increase of phantom size, the optimal monochromatic energy increased. With the increased percentage of radiation dose on the low energy scan, the optimal monochromatic energy decreased. When maximizing the iodine CNR in monochromatic images, the optimal energy was lower than that when minimizing noise level. When the total radiation dose was equally distributed between low and high energy in dual-energy scans, for minimum noise, the optimal energies were 68, 71, 74, and 77 keV for small, medium, large, and extra-large (xlarge) phantoms, respectively; for maximum iodine CNR, the optimal energies were 66, 68, 70, 72 keV. With the optimal monochromatic energy, the noise level was similar to and the CNR was better than that in a single-energy scan at 120 kV for the same radiation dose. Compared to an 80 kV scan, however, the iodine CNR in monochromatic images was lower for the small, medium, and large phantoms. Conclusions: In dual-source dual-energy CT, optimal virtual monochromatic energy depends on patient size, dose partitioning, and the image quality metric optimized. With the optimal monochromatic energy, the noise level was similar to and the iodine CNR was better than that in 120 kV images for the same radiation dose. Compared to single-energy 80 kV images, the iodine CNR in virtual monochromatic images was lower for small to large phantom sizes.

Yu Lifeng; Christner, Jodie A.; Leng Shuai; Wang Jia; Fletcher, Joel G.; McCollough, Cynthia H. [Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905 (United States)

2011-12-15

363

Tissue Doppler imaging for diagnosis of coronary artery disease: a systematic review and meta-analysis  

PubMed Central

Global and regional left ventricular (LV) systolic dysfunction is a marker of coronary artery disease (CAD), which is conventionally assessed using two-dimensional echocardiography. Tissue Doppler imaging (TDI) has emerged as an adjunct tool in the diagnosis of regional wall motion abnormalities from CAD. We performed a systematic review and meta-analysis to assess the efficacy of TDI indices in the diagnosis of CAD. We searched MEDLINE and the Cochrane Library for controlled studies comparing TDI measurements in those with and without CAD as confirmed by coronary angiography. Meta-analyses of mean differences in TDI velocities between these populations were performed. Screening of titles and abstracts followed by full-text screening identified 8 studies. At rest, TDI was associated with a significant decrease in the pooled maximum systolic velocity among CAD patients compared to those without CAD [mean difference (MD): -0.66; 95% confidence interval (CI): -0.98 to ?0.34]. There were no significant differences in maximum early and late diastolic velocities. Post-stress, TDI was associated with a significant decrease in maximum early diastolic velocity (MD: -1.91; 95% CI: -2.74 to ?1.09) and maximum late diastolic velocity (MD: -1.57; 95% CI: -2.95 to ?0.18) among CAD patients compared to those without CAD. There was no significant difference in maximum systolic velocity post-stress. Our results suggest that TDI may have a role in the evaluation of CAD. Future studies should evaluate the incremental value of TDI velocities over LV ejection fraction and two dimensional wall motion analysis in the detection of CAD and assessment of its severity. (Word Count: 249) PMID:23199010

2012-01-01

364

Cone beam computed tomography radiation dose and image quality assessments.  

PubMed

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

Lofthag-Hansen, Sara

2010-01-01

365

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

NASA Astrophysics Data System (ADS)

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

Vítek, Stanislav

2014-09-01

366

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

SciTech Connect

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

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

2011-01-01

367

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

SciTech Connect

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

Lette, J.; Lapointe, J.; Waters, D.; Cerino, M.; Picard, M.; Gagnon, A. (Maisonneuve Hospital, Montreal, Quebec (Canada))

1990-11-15

368

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

SciTech Connect

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

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

1981-07-01

369

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

PubMed Central

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

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

2012-01-01

370

Magnetic Resonance Perfusion Imaging in Acute Ischemic Stroke Using Continuous Arterial Spin Labeling  

Microsoft Academic Search

Background and Purpose—Continuous arterial spin-labeled perfusion MRI (CASL-PI) uses electromagnetically labeled arterial blood water as a diffusible tracer to noninvasively measure cerebral blood flow (CBF). We hypothesized that CASL-PI could detect perfusion deficits and perfusion\\/diffusion mismatches and predict outcome in acute ischemic stroke. Methods—We studied 15 patients with acute ischemic stroke within 24 hours of symptom onset. With the use

Julio A. Chalela; David C. Alsop; Julio B. Gonzalez-Atavales; Joseph A. Maldjian; Scott E. Kasner; John A. Detre

371

Evaluation of scatter effects on image quality for breast tomosynthesis  

NASA Astrophysics Data System (ADS)

Digital breast tomosynthesis uses a limited number of low-dose x-ray projections to produce a three-dimensional (3D) tomographic reconstruction of the breast. The purpose of this investigation was to characterize and evaluate the effect of scatter radiation on image quality for breast tomosynthesis. Generated by a Monte Carlo simulation method, scatter point spread functions (PSF) were convolved over the field of view (FOV) to estimate the distribution of scatter for each angle of tomosynthesis projection. The results demonstrated that in the absence of scatter reduction techniques, the scatter-to-primary ratio (SPR) levels for the average breast are quite high (~0.4 at the centre of mass), and increased with increased breast thickness and with larger FOV. Associated with such levels of x-ray scatter are cupping artifacts, as well as reduced accuracy in reconstruction values. The effect of x-ray scatter on the contrast, noise, and signal-difference-to-noise ratio (SDNR) in tomosynthesis reconstruction was measured as a function of tumour size. For example, the contrast in the reconstructed central slice of a tumour-like mass (14 mm in diameter) was degraded by 30% while the inaccuracy of the voxel value was 28%, and the reduction of SDNR was 60%. We have quantified the degree to which scatter degrades the image quality over a wide range of parameters, including x-ray beam energy, breast thickness, breast diameter, and breast composition. However, even without a scatter rejection device, the contrast and SDNR in the reconstructed tomosynthesis slice is higher than that 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.

2007-03-01

372

Damage and quality assessment in wheat by NIR hyperspectral imaging  

NASA Astrophysics Data System (ADS)

Fusarium head blight is a fungal disease that affects the world's small grains, such as wheat and barley. Attacking the spikelets during development, the fungus causes a reduction of yield and grain of poorer processing quality. It also is a health concern because of the secondary metabolite, deoxynivalenol, which often accompanies the fungus. While chemical methods exist to measure the concentration of the mycotoxin and manual visual inspection is used to ascertain the level of Fusarium damage, research has been active in developing fast, optically based techniques that can assess this form of damage. In the current study a near-infrared (1000-1700 nm) hyperspectral image system was assembled and applied to Fusarium-damaged kernel recognition. With anticipation of an eventual multispectral imaging system design, 5 wavelengths were manually selected from a pool of 146 images as the most promising, such that when combined in pairs or triplets, Fusarium damage could be identified. We present the results of two pairs of wavelengths [(1199, 1474 nm) and (1315, 1474 nm)] whose reflectance values produced adequate separation of kernels of healthy appearance (i.e., asymptomatic condition) from kernels possessing Fusarium damage.

Delwiche, Stephen R.; Kim, Moon S.; Dong, Yanhong

2010-04-01

373

Comparison of rubidium-82 positron emission tomography and thallium-201 SPECT imaging for detection of coronary artery disease  

SciTech Connect

The diagnostic performance of rubidium-82 (Rb-82) positron emission tomography (PET) and thallium-201 (Tl-201) single-photon emission-computed tomography (SPECT) for detecting coronary artery disease was investigated in 81 patients (52 men, 29 women). PET studies using 60 mCi of Rb-82 were performed at baseline and after intravenous infusion of 0.56 mg/kg dipyridamole in conjunction with handgrip stress. Tl-201 SPECT was performed after dipyridamole-handgrip stress and, in a subset of patients, after treadmill exercise. Sensitivity, specificity and overall diagnostic accuracy were assessed using both visually and quantitatively interpreted coronary angiograms. The overall sensitivity, specificity and accuracy of PET for detection of coronary artery disease (greater than 50% diameter stenosis) were 84, 88 and 85%, respectively. In comparison, the performance of SPECT revealed a sensitivity of 84%, specificity of 53% (p less than 0.05 vs PET) and accuracy of 79%. Similar results were obtained using either visual or quantitative angiographic criteria for severity of coronary artery disease. In 43 patients without prior myocardial infarction, the sensitivity for detection of disease was 71 and 73%, respectively, similar for both PET and SPECT. There was no significant difference in diagnostic performance between imaging modalities when 2 different modes of stress (exercise treadmill vs intravenous dipyridamole plus handgrip) were used with SPECT imaging. Thus, Rb-82 PET provides improved specificity compared with Tl-201 SPECT for identifying coronary artery disease, most likely due to the higher photon energy of Rb-82 and attenuation correction provided by PET. However, post-test referral cannot be entirely excluded as a potential explanation for the lower specificity of Tl-201 SPECT.

Stewart, R.E.; Schwaiger, M.; Molina, E.; Popma, J.; Gacioch, G.M.; Kalus, M.; Squicciarini, S.; al-Aouar, Z.R.; Schork, A.; Kuhl, D.E. (University of Michigan Medical Center, Department of Internal Medicine, Ann Arbor (USA))

1991-06-15