The Experts below are selected from a list of 38502 Experts worldwide ranked by ideXlab platform
Alfredo Ruggeri - One of the best experts on this subject based on the ideXlab platform.
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EMBC - Automatic estimation of corneal nerves focused tortuosities
Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Inte, 2016Co-Authors: Pedro Guimarães, Jeff Wigdahl, Alfredo RuggeriAbstract:The correlation between corneal nerve Tortuosity and pathology has been shown multiple times. However, because there isn't any defacto definition of Tortuosity, reproducibility is poor. Indeed, many studies still rely on the manual observation and judgment of Tortuosity. Recently, two distinct forms of corneal nerve Tortuosity have been identified, describing either short-range or long-range directional changes. In this study we were able to develop automatic corneal nerve Tortuosity measurements that correctly and independently represent these two Tortuosity definitions. Furthermore, we show that a combination of mathematical Tortuosity measurements improves on single metric results.
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automatic evaluation of corneal nerve Tortuosity in images from in vivo confocal microscopy
Investigative Ophthalmology & Visual Science, 2011Co-Authors: Fabio Scarpa, Xiaodong Zheng, Yuichi Ohashi, Alfredo RuggeriAbstract:PURPOSE. An algorithm and a computer program for the automatic grading of corneal nerve Tortuosity are proposed and evaluated. METHODS. Thirty images of the corneal subbasal nerve plexus with different grades of Tortuosity were acquired with a scanning laser confocal microscope in normal and pathologic subjects. Nerves were automatically traced with an algorithm previously developed, and a Tortuosity measure was computed with the proposed method, based on the number of changes in the curvature sign and on the amplitude (maximum distance of the curve from the underlying chord) of the nerve curves. These measures were evaluated according to their capability to reproduce the expert classification of images into three groups of Tortuosity (low, mid, and high). This classification was also compared with measures provided by other methods proposed in the literature to evaluate nerve Tortuosity. RESULTS. Among all considered methods, the one proposed herein allows a minimum of classification errors (only 2 in 30 images) and the highest Krippendorff concordance coefficient (0.96). Furthermore, it is the only one that can provide a significant difference (P < 0.01) between all pairs of Tortuosity classes. CONCLUSIONS. The results provided by the proposed system confirmed its ability to perform a clinically significant evaluation of corneal nerve Tortuosity.
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a novel method for the automatic grading of retinal vessel Tortuosity
IEEE Transactions on Medical Imaging, 2008Co-Authors: Enrico Grisan, M. Foracchia, Alfredo RuggeriAbstract:Tortuosity is among the first alterations in the retinal vessel network to appear in many retinopathies, such as those due to hypertension. An automatic evaluation of retinal vessel Tortuosity would help the early detection of such retinopathies. Quite a few techniques for Tortuosity measurement and classification have been proposed, but they do not always match the clinical concept of Tortuosity. This justifies the need for a new definition, able to express in mathematical terms the Tortuosity as perceived by ophthalmologists. We propose here a new algorithm for the evaluation of Tortuosity in vessels recognized in digital fundus images. It is based on partitioning each vessel in segments of constant-sign curvature and then combining together each evaluation of such segments and their number. The algorithm has been compared with other available Tortuosity measures on a set of 30 arteries and one of 30 veins from 60 different images. These vessels had been preliminarily ordered by a retina specialist by increasing perceived Tortuosity. The proposed algorithm proved to be the best one in matching the clinically perceived vessel Tortuosity.
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A novel method for the automatic evaluation of retinal vessel Tortuosity
IEEE transactions on medical imaging, 2008Co-Authors: Enrico Grisan, M. Foracchia, Alfredo RuggeriAbstract:Tortuosity is among the first alterations in retinal vessel network to appear in many retinopathies. Automatic evaluation of retinal vessel Tortuosity is thus a valuable tool for early detection of vascular suffering. Quite a few techniques for Tortuosity measurement and classification have been proposed, but they do not always match the clinical concept of Tortuosity. This justifies the need for a new definition, able to express in mathematical terms the Tortuosity as perceived by ophthalmologists. We propose here a new algorithm for the evaluation of Tortuosity in vessels extracted from digital fundus images. It is based on the partitioning of each vessel in segments of constant-sign curvature and on the combination between the number of such segments and their curvature values. This algorithm has been compared with the other Tortuosity measures on a set of 20 vessels from 10 different images. These vessels had been preliminarily ordered by an expert ophthalmologist in order of increasing perceived Tortuosity. The proposed algorithm proved to be the best one as regards arterial Tortuosity and among the best for vein Tortuosity evaluation.
Vm Belvroy - One of the best experts on this subject based on the ideXlab platform.
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Tortuosity of the Descending Thoracic Aorta in Patients with Aneurysm and Type B Dissection
'Springer Science and Business Media LLC', 2020Co-Authors: Vm Belvroy, De Beaufort Hwl, Ja ,van Herwaarden, Bismuth J, Piffaretti G, Fl Moll, Trimarchi SAbstract:OBJECTIVE: Tortuosity in the descending thoracic aorta (DTA) comes with aging and increases the risk of endoleaks after TEVAR. With this report, we would like to define and classify Tortuosity in the DTA of patients with thoracic aortic disease. METHODS: Retrospective case-control study of two hundred seven patients, comparing sixty-nine controls without aortic disease (CG), to sixty-nine patients with descending thoracic aortic aneurysm (AG) and sixty-nine patients with type B aortic dissection (DG). 3Mensio Vascular software was used to analyze CTA scans and collect the following measurements; Tortuosity index, curvature ratio and the maximum Tortuosity of the DTA. The DTA was divided into four equal zones. The maximum Tortuosity was divided into three groups: low (<30\ub0), moderate (30\ub0-60\ub0) and high Tortuosity (>60\ub0). RESULTS: Compared to the CG, Tortuosity was more pronounced in the DG, and even more in the AG, evidenced by the Tortuosity index (1.11 vs. 1.20 vs. 1.31; p\u2009<\u20090.001), curvature ratio (1.00 vs. 1.01 vs. 1.03; p\u2009<\u20090.001), maximum Tortuosity in degrees (28.17 vs. 33.29 vs. 43.83; p\u2009<\u20090.001) and group of Tortuosity (p\u2009<\u20090.001). The maximum Tortuosity was further distal for the DG and AG, evidenced by the zone of maximum Tortuosity (4A vs. 4B vs. 4B; p\u2009<\u20090.001). CONCLUSION: This study shows that Tortuosity in the DTA is more prominent in diseased aortas, especially in aneurysmal disease. This phenomenon needs to be taken into account during planning of TEVAR to prevent stent graft-related complications and to obtain positive long-term outcome
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Tortuosity of the descending thoracic aorta normal values by age
PLOS ONE, 2019Co-Authors: Vm Belvroy, Hector W L De Beaufort, Joost A Van Herwaarden, Jean Bismuth, Frans L Moll, Santi TrimarchiAbstract:Background Aging changes the aorta in length, Tortuosity and diameter. This is relevant in thoracic endovascular aortic repair (TEVAR) and in the long term follow up. Methods and results Two groups of hundred patients 60°). A linear regression model was built to test the effect of age and gender on Tortuosity. Tortuosity was more pronounced in the ≥ 65 compared to the < 65 group (Tortuosity index: 1.05 vs. 1.14, respectively; p < 0.001), curvature ratio (1.00 vs. 1.01; p < 0.001), maximum Tortuosity (22.24 vs. 27.26; p < 0.001), and group of angulation (low vs. low; p < 0.001). Additionally, the location of maximum Tortuosity was further distal for the ≥ 65 group (level of vertebrae; 5.00 vs. 5.00; p < 0.001), and zone of maximum Tortuosity (4A vs. 4A; p < 0.001). There was no significant difference between male and female subjects. Conclusion Normal DTA Tortuosity increases with age. This is important to understand natural aging and for TEVAR planning and follow-up.
Enrico Grisan - One of the best experts on this subject based on the ideXlab platform.
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a novel method for the automatic grading of retinal vessel Tortuosity
IEEE Transactions on Medical Imaging, 2008Co-Authors: Enrico Grisan, M. Foracchia, Alfredo RuggeriAbstract:Tortuosity is among the first alterations in the retinal vessel network to appear in many retinopathies, such as those due to hypertension. An automatic evaluation of retinal vessel Tortuosity would help the early detection of such retinopathies. Quite a few techniques for Tortuosity measurement and classification have been proposed, but they do not always match the clinical concept of Tortuosity. This justifies the need for a new definition, able to express in mathematical terms the Tortuosity as perceived by ophthalmologists. We propose here a new algorithm for the evaluation of Tortuosity in vessels recognized in digital fundus images. It is based on partitioning each vessel in segments of constant-sign curvature and then combining together each evaluation of such segments and their number. The algorithm has been compared with other available Tortuosity measures on a set of 30 arteries and one of 30 veins from 60 different images. These vessels had been preliminarily ordered by a retina specialist by increasing perceived Tortuosity. The proposed algorithm proved to be the best one in matching the clinically perceived vessel Tortuosity.
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A novel method for the automatic evaluation of retinal vessel Tortuosity
IEEE transactions on medical imaging, 2008Co-Authors: Enrico Grisan, M. Foracchia, Alfredo RuggeriAbstract:Tortuosity is among the first alterations in retinal vessel network to appear in many retinopathies. Automatic evaluation of retinal vessel Tortuosity is thus a valuable tool for early detection of vascular suffering. Quite a few techniques for Tortuosity measurement and classification have been proposed, but they do not always match the clinical concept of Tortuosity. This justifies the need for a new definition, able to express in mathematical terms the Tortuosity as perceived by ophthalmologists. We propose here a new algorithm for the evaluation of Tortuosity in vessels extracted from digital fundus images. It is based on the partitioning of each vessel in segments of constant-sign curvature and on the combination between the number of such segments and their curvature values. This algorithm has been compared with the other Tortuosity measures on a set of 20 vessels from 10 different images. These vessels had been preliminarily ordered by an expert ophthalmologist in order of increasing perceived Tortuosity. The proposed algorithm proved to be the best one as regards arterial Tortuosity and among the best for vein Tortuosity evaluation.
Peter H Whincup - One of the best experts on this subject based on the ideXlab platform.
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retinal arteriolar Tortuosity and cardiovascular risk factors in a multi ethnic population study of 10 year old children the child heart and health study in england chase
Arteriosclerosis Thrombosis and Vascular Biology, 2011Co-Authors: Christopher G Owen, Alicja R Rudnicka, Claire M Nightingale, Robert Mullen, Sarah Barman, Naveed Sattar, Derek G Cook, Peter H WhincupAbstract:Objective— To examine the association between cardiovascular risk factors and retinal arteriolar Tortuosity in a multi-ethnic child population. Methods and Results— Cross sectional study of 986 UK primary school children of South Asian, black African Caribbean, and white European origin aged 10 to 11 years. Anthropometric measurements and retinal imaging were carried out and a fasting blood sample collected. Digital images of retinal arterioles were analyzed using a validated semiautomated measure of Tortuosity. Associations between Tortuosity and cardiometabolic risk factors were analyzed using multi-level linear regression, adjusted for gender, age, ethnicity, arteriole branch status, month, and school. Levels of arteriolar Tortuosity were similar in boys and girls and in different ethnic groups. Retinal arteriolar Tortuosity was positively associated with levels of triglyceride, total and LDL cholesterol, and systolic and diastolic blood pressure. One standard deviation increases in these risk factors were associated with 3.7% (95% CI: 1.2%, 6.4%), 3.3% (0.9%, 5.8%), 3.1% (0.6%, 5.6%), 2.0% (−0.3%, 4.2%), and 2.3% (0.1%, 4.6%) increases in Tortuosity, respectively. Adiposity, insulin resistance, and blood glucose showed no associations with Tortuosity. Conclusion— Established cardiovascular risk factors, strongly linked to coronary heart disease in adulthood, may influence retinal arteriolar Tortuosity at the end of the first decade of life.
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measuring retinal vessel Tortuosity in 10 year old children validation of the computer assisted image analysis of the retina caiar program
Investigative Ophthalmology & Visual Science, 2009Co-Authors: Christopher G Owen, Alicja R Rudnicka, Sarah Barman, Peter H Whincup, Robert J Mullen, Dorothy Monekosso, Carl PatersonAbstract:PURPOSE: To examine the agreement of a novel computer program measuring retinal vessel Tortuosity with subjective assessment of Tortuosity in school-aged children. METHODS: Cross-sectional study of 387 retinal vessels (193 arterioles, 194 veins) from 28 eyes of 14 children (aged 10 years). Retinal digital images were analyzed using the Computer Assisted Image Analysis of the Retina (CAIAR) program, including 14 measures of Tortuosity. Vessels were graded (from 0 = none; to 5 = tortuous) independently by two observers. Interobserver agreement was assessed by using kappa statistics. Agreement with all 14 objective measures was assessed with correlation/regression analyses. Intersession repeatability (comparing morning and afternoon sessions) of Tortuosity indices was calculated. RESULTS: Interobserver agreement of vessel Tortuosity within one grade was high (kappa = 0.97), with total agreement in 56% of grades and 42% differing by +/-1 grade. Tortuosity indices based on subdivided chord length methods showed strong log-linear associations with agreed subjective grades (typically r > 0.6; P
Jennifer R. Chao - One of the best experts on this subject based on the ideXlab platform.
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Familial retinal arteriolar Tortuosity and quantification of vascular Tortuosity using swept-source optical coherence tomography angiography.
American journal of ophthalmology case reports, 2019Co-Authors: Steven S. Saraf, Ariel J. Tyring, Chieh-li Chen, Robert E. Kalina, Ruikang K. Wang, Jennifer R. ChaoAbstract:Abstract Purpose Familial retinal arteriolar Tortuosity (FRAT) is a rare autosomal dominant disorder that is characterized by Tortuosity of the second and higher order retinal arterioles. We implement swept-source optical coherence tomography angiography (SS-OCTA) to quantify vessel Tortuosity in patients with FRAT. We hypothesize that patients with FRAT will have higher retinal arteriole Tortuosity when compared to controls. Methods Patients were scanned with a SS-OCTA device (Plex Elite 9000, Carl Zeiss Meditec, Dublin, CA). Images of a 12 × 12 mm2 area centered on the fovea were processed, and retinal vessels >23.5 μm in diameter were identified. An automatic Tortuosity measurement program written in MATLAB was used to assess vessel Tortuosity. Branch points in the vessels were detected and used to separate the vasculature into individual segments. The Tortuosity was measured by calculating the arc-chord ratio of each vessel segment, where a minimum value of 1 indicated a straight vessel and higher values corresponded to increasing Tortuosity. Results Two patients (4 eyes) with a known history of FRAT and six controls (12 eyes) were enrolled in the study. The mean Tortuosity of all vessel segments (MTVS) in scans of FRAT eyes was on average 1.1244 [range: 1.1044–1.1438] while for control eyes it was 1.0818 [range: 1.0746–1.0872]. Average MTVS of FRAT eyes was significantly higher compared to control eyes (p = 0.03). Conclusions and Importance Our results are consistent with the hypothesis that patients with FRAT have higher objective measurements of Tortuosity compared to controls. Broader applications of this method may be of benefit in other retinal diseases with changes in retinal vessel configuration.
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Familial retinal arteriolar Tortuosity and quantification of vascular Tortuosity using swept-source optical coherence tomography angiography
Elsevier, 2019Co-Authors: Steven S. Saraf, Ariel J. Tyring, Chieh-li Chen, Robert E. Kalina, Ruikang K. Wang, Jennifer R. ChaoAbstract:Purpose: Familial retinal arteriolar Tortuosity (FRAT) is a rare autosomal dominant disorder that is characterized by Tortuosity of the second and higher order retinal arterioles. We implement swept-source optical coherence tomography angiography (SS-OCTA) to quantify vessel Tortuosity in patients with FRAT. We hypothesize that patients with FRAT will have higher retinal arteriole Tortuosity when compared to controls. Methods: Patients were scanned with a SS-OCTA device (Plex Elite 9000, Carl Zeiss Meditec, Dublin, CA). Images of a 12 × 12 mm2 area centered on the fovea were processed, and retinal vessels >23.5 μm in diameter were identified. An automatic Tortuosity measurement program written in MATLAB was used to assess vessel Tortuosity. Branch points in the vessels were detected and used to separate the vasculature into individual segments. The Tortuosity was measured by calculating the arc-chord ratio of each vessel segment, where a minimum value of 1 indicated a straight vessel and higher values corresponded to increasing Tortuosity. Results: Two patients (4 eyes) with a known history of FRAT and six controls (12 eyes) were enrolled in the study. The mean Tortuosity of all vessel segments (MTVS) in scans of FRAT eyes was on average 1.1244 [range: 1.1044–1.1438] while for control eyes it was 1.0818 [range: 1.0746–1.0872]. Average MTVS of FRAT eyes was significantly higher compared to control eyes (p = 0.03). Conclusions and Importance: Our results are consistent with the hypothesis that patients with FRAT have higher objective measurements of Tortuosity compared to controls. Broader applications of this method may be of benefit in other retinal diseases with changes in retinal vessel configuration. Keywords: Familial retinal arteriolar Tortuosity, Vascular Tortuosity, OCT angiograph
