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Title: DECT evaluation of noncalcified coronary artery plaque

Abstract

Purpose: Composition of the coronary artery plaque is known to have critical role in heart attack. While calcified plaque can easily be diagnosed by conventional CT, it fails to distinguish between fibrous and lipid rich plaques. In the present paper, the authors discuss the experimental techniques and obtain a numerical algorithm by which the electron density (ρ{sub e}) and the effective atomic number (Z{sub eff}) can be obtained from the dual energy computed tomography (DECT) data. The idea is to use this inversion method to characterize and distinguish between the lipid and fibrous coronary artery plaques. Methods: For the purpose of calibration of the CT machine, the authors prepare aqueous samples whose calculated values of (ρ{sub e}, Z{sub eff}) lie in the range of (2.65 × 10{sup 23} ≤ ρ{sub e} ≤ 3.64 × 10{sup 23}/cm{sup 3}) and (6.80 ≤ Z{sub eff} ≤ 8.90). The authors fill the phantom with these known samples and experimentally determine HU(V{sub 1}) and HU(V{sub 2}), with V{sub 1},V{sub 2} = 100 and 140 kVp, for the same pixels and thus determine the coefficients of inversion that allow us to determine (ρ{sub e}, Z{sub eff}) from the DECT data. The HU(100) and HU(140) for themore » coronary artery plaque are obtained by filling the channel of the coronary artery with a viscous solution of methyl cellulose in water, containing 2% contrast. These (ρ{sub e}, Z{sub eff}) values of the coronary artery plaque are used for their characterization on the basis of theoretical models of atomic compositions of the plaque materials. These results are compared with histopathological report. Results: The authors find that the calibration gives ρ{sub e} with an accuracy of ±3.5% while Z{sub eff} is found within ±1% of the actual value, the confidence being 95%. The HU(100) and HU(140) are found to be considerably different for the same plaque at the same position and there is a linear trend between these two HU values. It is noted that pure lipid type plaques are practically nonexistent, and microcalcification, as observed in histopathology, has to be taken into account to explain the nature of the observed (ρ{sub e}, Z{sub eff}) data. This also enables us to judge the composition of the plaque in terms of basic model which considers the plaque to be composed of fibres, lipids, and microcalcification. Conclusions: This simple and reliable method has the potential as an effective modality to investigate the composition of noncalcified coronary artery plaques and thus help in their characterization. In this inversion method, (ρ{sub e}, Z{sub eff}) of the scanned sample can be found by eliminating the effects of the CT machine and also by ensuring that the determination of the two unknowns (ρ{sub e}, Z{sub eff}) does not interfere with each other and the nature of the plaque can be identified in terms of a three component model.« less

Authors:
 [1];  [2]; ; ; ;  [3]; ;  [4]; ;  [5];  [6];  [7]; ;  [8];  [9]
  1. Medical Imaging Research Center and Colorectal Research Center, Shiraz University of Medical Science, Shiraz 719 363 5899 (Iran, Islamic Republic of)
  2. BGVS Chemical Engineering Building (Old), Indian Institute of Science, Bangalore 560012 (India)
  3. Department of Forensic Medicine, All India Institute of Medical Sciences, New Delhi 110029 (India)
  4. Department of Cardiac-Radiology, All India Institute of Medical Sciences, New Delhi 110029 (India)
  5. Department of Pathology, All India Institute of Medical Sciences, New Delhi 110029 (India)
  6. Department of Cardiology, All India Institute of Medical Sciences, New Delhi 110029 (India)
  7. Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore 560012 (India)
  8. Department of Cardiac-Biochemistry, All India Institute of Medical Sciences, New Delhi 110029 (India)
  9. Department of Medical Physics Unit IRCH, All India Institute of Medical Sciences, New Delhi 110029 (India)
Publication Date:
OSTI Identifier:
22482356
Resource Type:
Journal Article
Resource Relation:
Journal Name: Medical Physics; Journal Volume: 42; Journal Issue: 10; Other Information: (c) 2015 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; ACCURACY; ALGORITHMS; CALIBRATION; COMPARATIVE EVALUATIONS; COMPUTERIZED TOMOGRAPHY; CORONARIES; DIAGNOSIS; LIPIDS; PHANTOMS

Citation Formats

Ravanfar Haghighi, Rezvan, Chatterjee, S., Tabin, Milo, Singh, Rishi P., Sharma, Munish, Krishna, Karthik, Sharma, Sanjiv, Jagia, Priya, Ray, Ruma, Arava, Sudhir, Yadav, Rakesh, Vani, V. C., Lakshmi, R., Kumar, Pratik, E-mail: drpratikkumar@gmail.com, and Mandal, Susama R. DECT evaluation of noncalcified coronary artery plaque. United States: N. p., 2015. Web. doi:10.1118/1.4929935.
Ravanfar Haghighi, Rezvan, Chatterjee, S., Tabin, Milo, Singh, Rishi P., Sharma, Munish, Krishna, Karthik, Sharma, Sanjiv, Jagia, Priya, Ray, Ruma, Arava, Sudhir, Yadav, Rakesh, Vani, V. C., Lakshmi, R., Kumar, Pratik, E-mail: drpratikkumar@gmail.com, & Mandal, Susama R. DECT evaluation of noncalcified coronary artery plaque. United States. doi:10.1118/1.4929935.
Ravanfar Haghighi, Rezvan, Chatterjee, S., Tabin, Milo, Singh, Rishi P., Sharma, Munish, Krishna, Karthik, Sharma, Sanjiv, Jagia, Priya, Ray, Ruma, Arava, Sudhir, Yadav, Rakesh, Vani, V. C., Lakshmi, R., Kumar, Pratik, E-mail: drpratikkumar@gmail.com, and Mandal, Susama R. Thu . "DECT evaluation of noncalcified coronary artery plaque". United States. doi:10.1118/1.4929935.
@article{osti_22482356,
title = {DECT evaluation of noncalcified coronary artery plaque},
author = {Ravanfar Haghighi, Rezvan and Chatterjee, S. and Tabin, Milo and Singh, Rishi P. and Sharma, Munish and Krishna, Karthik and Sharma, Sanjiv and Jagia, Priya and Ray, Ruma and Arava, Sudhir and Yadav, Rakesh and Vani, V. C. and Lakshmi, R. and Kumar, Pratik, E-mail: drpratikkumar@gmail.com and Mandal, Susama R.},
abstractNote = {Purpose: Composition of the coronary artery plaque is known to have critical role in heart attack. While calcified plaque can easily be diagnosed by conventional CT, it fails to distinguish between fibrous and lipid rich plaques. In the present paper, the authors discuss the experimental techniques and obtain a numerical algorithm by which the electron density (ρ{sub e}) and the effective atomic number (Z{sub eff}) can be obtained from the dual energy computed tomography (DECT) data. The idea is to use this inversion method to characterize and distinguish between the lipid and fibrous coronary artery plaques. Methods: For the purpose of calibration of the CT machine, the authors prepare aqueous samples whose calculated values of (ρ{sub e}, Z{sub eff}) lie in the range of (2.65 × 10{sup 23} ≤ ρ{sub e} ≤ 3.64 × 10{sup 23}/cm{sup 3}) and (6.80 ≤ Z{sub eff} ≤ 8.90). The authors fill the phantom with these known samples and experimentally determine HU(V{sub 1}) and HU(V{sub 2}), with V{sub 1},V{sub 2} = 100 and 140 kVp, for the same pixels and thus determine the coefficients of inversion that allow us to determine (ρ{sub e}, Z{sub eff}) from the DECT data. The HU(100) and HU(140) for the coronary artery plaque are obtained by filling the channel of the coronary artery with a viscous solution of methyl cellulose in water, containing 2% contrast. These (ρ{sub e}, Z{sub eff}) values of the coronary artery plaque are used for their characterization on the basis of theoretical models of atomic compositions of the plaque materials. These results are compared with histopathological report. Results: The authors find that the calibration gives ρ{sub e} with an accuracy of ±3.5% while Z{sub eff} is found within ±1% of the actual value, the confidence being 95%. The HU(100) and HU(140) are found to be considerably different for the same plaque at the same position and there is a linear trend between these two HU values. It is noted that pure lipid type plaques are practically nonexistent, and microcalcification, as observed in histopathology, has to be taken into account to explain the nature of the observed (ρ{sub e}, Z{sub eff}) data. This also enables us to judge the composition of the plaque in terms of basic model which considers the plaque to be composed of fibres, lipids, and microcalcification. Conclusions: This simple and reliable method has the potential as an effective modality to investigate the composition of noncalcified coronary artery plaques and thus help in their characterization. In this inversion method, (ρ{sub e}, Z{sub eff}) of the scanned sample can be found by eliminating the effects of the CT machine and also by ensuring that the determination of the two unknowns (ρ{sub e}, Z{sub eff}) does not interfere with each other and the nature of the plaque can be identified in terms of a three component model.},
doi = {10.1118/1.4929935},
journal = {Medical Physics},
number = 10,
volume = 42,
place = {United States},
year = {Thu Oct 15 00:00:00 EDT 2015},
month = {Thu Oct 15 00:00:00 EDT 2015}
}
  • Radionuclide techniques have greatly enhanced noninvasive evaluation in the patient with suspected coronary artery disease (CAD). Although these techniques have high sensitivity and specificity, the published data contain significant inconsistencies and inaccuracies. Coronary arteriography remains the definitive method of determining the presence, site, severity and operability of CAD. Although the procedure is invasive, recent studies have shown that complication rates have been reduced to an acceptably low level, particularly in laboratories with extensive experience. The economic aspects of coronary arteriography are complex. Survey data acquired in early 1981 from 54 active cardiac catheterization laboratories around the country showed that themore » mean technical charge billed by the hospital for coronary angiographic procedures was /760 (range /307-1470). Analysis of the actual costs of the procedure to the hospital indicates that in most cases, these costs far exceed /760. Hospital budgeting practices in many states fail to create any incentive to match charges with costs. The mean professional fee billed by physicians for coronary arteriography was /640 (range /200-1200). An estimated 275,000 coronary arteriograms are performed annually in the United States, yielding a total cost of /577,500,000. Opportunities for significant cost cutting are limited, and seem to lie primarily in improving the utilization of existing laboratories that are underutilized. Unresolved economic, ethical and social issues pertaining to coronary arteriography include: centralizing the procedure in a smaller number of centers around the country; self-referral of patients for coronary arteriography; establishing training standards for coronary angiographers and performance standards for angiographic equipment; acceptable levels of sensitivity in noninvasive screening for suspected CAD; and utilization of coronary arteriography throughout the country.« less
  • Purpose: The authors are developing a computer-aided detection system to assist radiologists in analysis of coronary artery disease in coronary CT angiograms (cCTA). This study evaluated the accuracy of the authors’ coronary artery segmentation and tracking method which are the essential steps to define the search space for the detection of atherosclerotic plaques. Methods: The heart region in cCTA is segmented and the vascular structures are enhanced using the authors’ multiscale coronary artery response (MSCAR) method that performed 3D multiscale filtering and analysis of the eigenvalues of Hessian matrices. Starting from seed points at the origins of the left andmore » right coronary arteries, a 3D rolling balloon region growing (RBG) method that adapts to the local vessel size segmented and tracked each of the coronary arteries and identifies the branches along the tracked vessels. The branches are queued and subsequently tracked until the queue is exhausted. With Institutional Review Board approval, 62 cCTA were collected retrospectively from the authors’ patient files. Three experienced cardiothoracic radiologists manually tracked and marked center points of the coronary arteries as reference standard following the 17-segment model that includes clinically significant coronary arteries. Two radiologists visually examined the computer-segmented vessels and marked the mistakenly tracked veins and noisy structures as false positives (FPs). For the 62 cases, the radiologists marked a total of 10191 center points on 865 visible coronary artery segments. Results: The computer-segmented vessels overlapped with 83.6% (8520/10191) of the center points. Relative to the 865 radiologist-marked segments, the sensitivity reached 91.9% (795/865) if a true positive is defined as a computer-segmented vessel that overlapped with at least 10% of the reference center points marked on the segment. When the overlap threshold is increased to 50% and 100%, the sensitivities were 86.2% and 53.4%, respectively. For the 62 test cases, a total of 55 FPs were identified by radiologist in 23 of the cases. Conclusions: The authors’ MSCAR-RBG method achieved high sensitivity for coronary artery segmentation and tracking. Studies are underway to further improve the accuracy for the arterial segments affected by motion artifacts, severe calcified and noncalcified soft plaques, and to reduce the false tracking of the veins and other noisy structures. Methods are also being developed to detect coronary artery disease along the tracked vessels.« less
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