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Navegando Ciência da Computação por Autor "ACHARYA, U. R."
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Artigo Automated carotid artery intima layer regional segmentation(2011) MEIBURGER, K. M.; MOLINA, F.; ACHARYA, U. R.; SABA, L.; RODRIGUES, P.; LIBONI, W.; NICOLAIDES, A.; SURI, J. S.Evaluation of the carotid artery wall is essential for the assessment of a patient's cardiovascular risk or for the diagnosis of cardiovascular pathologies. This paper presents a new, completely user-independent algorithm called carotid artery intima layer regional segmentation (CAILRS, a class of AtheroEdge™ systems), which automatically segments the intima layer of the far wall of the carotid ultrasound artery based on mean shift classification applied to the far wall. Further, the system extracts the lumen-intima and media-adventitia borders in the far wall of the carotid artery. Our new system is characterized and validated by comparing CAILRS borders with the manual tracings carried out by experts. The new technique is also benchmarked with a semi-automatic technique based on a first-order absolute moment edge operator (FOAM) and compared to our previous edge-based automated methods such as CALEX (Molinari et al 2010 J. Ultrasound Med. 29 399-418, 2010 IEEE Trans. Ultrason. Ferroelectr. Freq. Control 57 1112-24), CULEX (Delsanto et al 2007 IEEE Trans. Instrum. Meas. 56 1265-74, Molinari et al 2010 IEEE Trans. Ultrason. Ferroelectr. Freq. Control 57 1112-24), CALSFOAM (Molinari et al Int. Angiol. (at press)), and CAUDLES-EF (Molinari et al J. Digit. Imaging (at press)). Our multi-institutional database consisted of 300 longitudinal B-mode carotid images. In comparison to semi-automated FOAM, CAILRS showed the IMT bias of -0.035 0.186 mm while FOAM showed -0.016 0.258 mm. Our IMT was slightly underestimated with respect to the ground truth IMT, but showed uniform behavior over the entire database. CAILRS outperformed all the four previous automated methods. The system's figure of merit was 95.6%, which was lower than that of the semi-automated method (98%), but higher than that of the other automated techniques. © 2011 Institute of Physics and Engineering in Medicine.Artigo CARES 2.0: Completely automated robust edge snapper for cimt measurement in 300 ultrasound images-a two stage paradigm(2011) MOLINARI, F.; ACHARYA, U. R.; ZENG, G.; MEIBURGER, K. M.; RODRIGUES, P. S.; SABA, L.; SURI, J. S.The carotid intima-media thickness (IMT) is a widely used marker associated to the risk of cardiovascular diseases and to atherosclerosis progression. IMT measurement requires high accuracy and reproducibility. Computer-aided measurements improve accuracy and precision, but usually require user interaction. In this paper we proposed an improved method (called CARES 2.0) over the previously developed technique (called CARES 1.0). CARES 2.0 is a two stage process: Stage-I adapts an integrated approach of intelligent image feature extraction and line fitting for far adventitia border detection. Stage-II is a first order absolute moment (FOAM 1.0) coupled to a novel and improved heuristic search for the lumen-intima (LI) and media-adventitia (MA) peaks. CARES 2.0 brings in two novel scientific contributions: (a) ability to improve Stage-I to compare jugular vein versus carotid artery and (b) introduction bi-directional and robust FOAM. The improved method is a fully automated IMT measurement technique, and was validated on a multi-institutional database of 300 images exhibiting normal and pathologic carotids. We benchmarked CARES 2.0 against previously developed CALEX 1.0 and user-driven FOAM 1.0. CARES 2.0 showed an IMT measurement bias equal to -0.032±0.178 mm, which was better than CALEX 1.0 (0.070±0.331 mm), FOAM 1.0 (-0.091±0.161 mm) and CARES 1.0 (0.035±0.198 mm), respectively. Thus CARES 2.0 showed an improvement of 54% over CALEX 1.0, 65% over stand alone FOAM 1.0 and 9% over CARES 1.0. Compared to CARES 1.0, CARES 2.0 improved the reproducibility by 10%. CARES 2.0 ensured complete automation and increased the reproducibility of the IMT measurement, a step closer for clinical usage. Copyright © 2011 American Scientific Publishers.Artigo de evento CARES 3.0: A two stage system combining feature-based recognition and edge-based segmentation for CIMT measurement on a multi-institutional ultrasound database of 300 images(2011-08-30) MOLINARI, F.; MELBURGER, K. M.; ACHARYA, U. R.; ZENG, G.; Paulo Rodrigues; SABA, L.; NICOLAIDES, A.; SURI, J. S.The intima-media thickness of the carotid artery (CIMT) is a validated marker of atherosclerosis. Accurate CIMT measurement can be performed by specifically designed computer algorithms. We improved a previous CIMT measurement technique by introducing a smart heuristic search for the lumen-intima (LI) and media-adventitia (MA) interfaces of the carotid distal wall. We called this new release as CARES 3.0 (a class of AtheroEdge™ system, a patented technology from Global Biomedical Technologies, Inc., CA, USA). CARES 3.0 is completely automated and adopts an integrated approach for carotid location in the image frame, followed by segmentation based on edge snapper and heuristic search. CARES 3.0 was benchmarked against three other techniques on a 300 image multi-institutional database. One of the techniques was user-driven. The CARES 3.0 CIMT measurement bias was -0.021±0.182 mm, which was better than that of the semi automated method (-0.036±0.183 mm). CARES 3.0 outperformed the other two fully automated methods. The Figure-of-Merit of CARES 3.0 was 97.4%, better than that of the semi-automated technique (95.4%). © 2011 IEEE.