The Experts below are selected from a list of 19179 Experts worldwide ranked by ideXlab platform
Evelyn Regar - One of the best experts on this subject based on the ideXlab platform.
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a novel method to assess coronary artery bifurcations by oct Cut Plane analysis for side branch ostial assessment from a main vessel pullback
European Journal of Echocardiography, 2015Co-Authors: Antonios Karanasos, Nienke S Van Ditzhuijzen, Jurgen Ligthart, Karen Witberg, Nicolas M Van Mieghem, Robertjan Van Geuns, Peter De Jaegere, Felix Zijlstra, Johan H C Reiber, Evelyn RegarAbstract:Aims In coronary bifurcations assessment, evaluation of side-branch (SB) ostia by an optical coherence tomography (OCT) pullback performed in the main branch (MB) could speed up lesion evaluation and minimize contrast volume. Dedicated software that reconstructs the cross-sections perpendicular to the SB centreline could improve this assessment. We aimed to validate a new method for assessing the SB ostium from an OCT pullback performed in the MB. Methods and results Thirty-one sets of frequency-domain OCT pullbacks from 28 patients, both from the MB and the SB of a coronary artery bifurcation were analysed. Measurements of the SB ostium from the SB pullback were used as a reference. Measurements of the SB ostium from the MB pullback were then performed in a laboratory setting by (i) conventional analysis and (ii) Cut-Plane analysis, and the measurement error for each analysis was estimated. Correlations of SB ostium measurements acquired from the MB pullback in comparison with reference measurements acquired from the SB pullback were higher with Cut-Plane analysis compared with conventional analysis, albeit not reaching statistical significance (area: r Cut-Plane = 0.927 vs. r conventional = 0.870, P = 0.256; mean diameter: r Cut-Plane = 0.918 vs. r conventional = 0.788, P = 0.056; minimum diameter: r Cut-Plane = 0.841 vs. r conventional = 0.812, P = 0.734; maximum diameter: r Cut-Plane = 0.770 vs. r conventional = 0.635, P = 0.316). Cut-Plane analysis was associated with lower absolute error than conventional analysis (area: 0.56 ± 0.45, vs. 1.50 ± 1.31 mm2, P < 0.001; mean diameter: 0.18 ± 0.14 vs. 0.44 ± 0.30 mm, P < 0.001). Conclusion Measurements of SB ostium performed in a laboratory setting by Cut-Plane analysis of an OCT pullback of the main branch have high correlation with reference measurements performed in a SB OCT pullback and lower error compared with conventional analysis.
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tct 386 Cut Plane analysis a new method of three dimensional oct rendering for side branch ostial assessment from a main vessel pullback
Journal of the American College of Cardiology, 2014Co-Authors: Antonios Karanasos, Nienke S Van Ditzhuijzen, Jurgen Ligthart, Nicolas M Van Mieghem, Robertjan Van Geuns, Peter De Jaegere, Felix Zijlstra, Johan H C Reiber, Evelyn RegarAbstract:In the assessment of coronary bifurcations, evaluation of side branch (SB) ostia by an optical coherence tomography (OCT) pullback performed in the main branch(MB) could speed up lesion evaluation. This assessment can be performed through dedicated software that renders the imaged segment in 3-D and
Jeremie Unterberger - One of the best experts on this subject based on the ideXlab platform.
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stochastic calculus for fractional brownian motion with hurst exponent h a rough path method by analytic extension
Annals of Probability, 2009Co-Authors: Jeremie UnterbergerAbstract:The d-dimensional fractional Brownian motion (FBM for short) B t = ((B (1) t ,.., B (d) t ), t ∈ R) with Hurst exponent α, α ∈ (0, 1), is a d-dimensional centered, self-similar Gaussian process with covariance E[B (i) s B (i) t ] = 1 2 δi,j (lsl 2α + ltl 2α ― |t ― s | 2α ). The long-standing problem of defining a stochastic integration with respect to FBM (and the related problem of solving stochastic differential equations driven by FBM) has been addressed successfully by several different methods, although in each case with a restriction on the range of either d or α. The case α = ½ corresponds to the usual stochastic integration with respect to Brownian motion, while most computations become singular when α gets under various threshhold values, due to the growing irregularity of the trajectories as α → 0. We provide here a new method valid for any d and for α > 1/4 by constructing an approximation Γ(e) t , e → 0, of FBM which allows to define iterated integrals, and then applying the geometric rough path theory. The approximation relies on the definition of an analytic process Γ z on the Cut Plane z ∈ C \ R of which FBM appears to be a boundary value, and allows to understand very precisely the well-known (see [5]) but as yet a little mysterious divergence of Levy's area for α → 1/4
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stochastic calculus for fractional brownian motion with hurst exponent h a rough path method by analytic extension
Annals of Probability, 2009Co-Authors: Jeremie UnterbergerAbstract:The d-dimensional fractional Brownian motion (FBM for short) Bt=((Bt(1), …, Bt(d)), t∈ℝ) with Hurst exponent α, α∈(0, 1), is a d-dimensional centered, self-similar Gaussian process with covariance ${\mathbb{E}}[B_{s}^{(i)}B_{t}^{(j)}]=\frac{1}{2}\delta_{i,j}(|s|^{2\alpha}+|t|^{2\alpha}-|t-s|^{2\alpha})$. The long-standing problem of defining a stochastic integration with respect to FBM (and the related problem of solving stochastic differential equations driven by FBM) has been addressed successfully by several different methods, although in each case with a restriction on the range of either d or α. The case α=½ corresponds to the usual stochastic integration with respect to Brownian motion, while most computations become singular when α gets under various threshhold values, due to the growing irregularity of the trajectories as α→0. We provide here a new method valid for any d and for α>¼ by constructing an approximation Γ(ɛ)t, ɛ→0, of FBM which allows to define iterated integrals, and then applying the geometric rough path theory. The approximation relies on the definition of an analytic process Γz on the Cut Plane z∈ℂ∖ℝ of which FBM appears to be a boundary value, and allows to understand very precisely the well-known (see [5]) but as yet a little mysterious divergence of Levy’s area for α→¼.
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stochastic calculus for fractional brownian motion with hurst exponent h 1 4 a rough path method by analytic extension
arXiv: Probability, 2007Co-Authors: Jeremie UnterbergerAbstract:The $d$-dimensional fractional Brownian motion (FBM for short) $B_t=((B_t^{(1)},...,B_t^{(d)}),t\in\mathbb{R})$ with Hurst exponent $\alpha$, $\alpha\in(0,1)$, is a $d$-dimensional centered, self-similar Gaussian process with covariance ${\mathbb{E}}[B_s^{(i)}B _t^{(j)}]={1/2}\delta_{i,j}(|s|^{2\alpha}+|t|^{2\alpha}-|t-s|^{2 \alpha}).$ The long-standing problem of defining a stochastic integration with respect to FBM (and the related problem of solving stochastic differential equations driven by FBM) has been addressed successfully by several different methods, although in each case with a restriction on the range of either $d$ or $\alpha$. The case $\alpha={1/2}$ corresponds to the usual stochastic integration with respect to Brownian motion, while most computations become singular when $\alpha$ gets under various threshhold values, due to the growing irregularity of the trajectories as $\alpha\to0$. We provide here a new method valid for any $d$ and for $\alpha>{1/4}$ by constructing an approximation $\Gamma(\varepsilon)_t$, $\varepsilon\to0$, of FBM which allows to define iterated integrals, and then applying the geometric rough path theory. The approximation relies on the definition of an analytic process $\Gamma_z$ on the Cut Plane $z\in\mathbb{C}\setminus\mathbb{R}$ of which FBM appears to be a boundary value, and allows to understand very precisely the well-known (see \citeCQ02) but as yet a little mysterious divergence of L\'evy's area for $\alpha\to{1/4}$.
Antonios Karanasos - One of the best experts on this subject based on the ideXlab platform.
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a novel method to assess coronary artery bifurcations by oct Cut Plane analysis for side branch ostial assessment from a main vessel pullback
European Journal of Echocardiography, 2015Co-Authors: Antonios Karanasos, Nienke S Van Ditzhuijzen, Jurgen Ligthart, Karen Witberg, Nicolas M Van Mieghem, Robertjan Van Geuns, Peter De Jaegere, Felix Zijlstra, Johan H C Reiber, Evelyn RegarAbstract:Aims In coronary bifurcations assessment, evaluation of side-branch (SB) ostia by an optical coherence tomography (OCT) pullback performed in the main branch (MB) could speed up lesion evaluation and minimize contrast volume. Dedicated software that reconstructs the cross-sections perpendicular to the SB centreline could improve this assessment. We aimed to validate a new method for assessing the SB ostium from an OCT pullback performed in the MB. Methods and results Thirty-one sets of frequency-domain OCT pullbacks from 28 patients, both from the MB and the SB of a coronary artery bifurcation were analysed. Measurements of the SB ostium from the SB pullback were used as a reference. Measurements of the SB ostium from the MB pullback were then performed in a laboratory setting by (i) conventional analysis and (ii) Cut-Plane analysis, and the measurement error for each analysis was estimated. Correlations of SB ostium measurements acquired from the MB pullback in comparison with reference measurements acquired from the SB pullback were higher with Cut-Plane analysis compared with conventional analysis, albeit not reaching statistical significance (area: r Cut-Plane = 0.927 vs. r conventional = 0.870, P = 0.256; mean diameter: r Cut-Plane = 0.918 vs. r conventional = 0.788, P = 0.056; minimum diameter: r Cut-Plane = 0.841 vs. r conventional = 0.812, P = 0.734; maximum diameter: r Cut-Plane = 0.770 vs. r conventional = 0.635, P = 0.316). Cut-Plane analysis was associated with lower absolute error than conventional analysis (area: 0.56 ± 0.45, vs. 1.50 ± 1.31 mm2, P < 0.001; mean diameter: 0.18 ± 0.14 vs. 0.44 ± 0.30 mm, P < 0.001). Conclusion Measurements of SB ostium performed in a laboratory setting by Cut-Plane analysis of an OCT pullback of the main branch have high correlation with reference measurements performed in a SB OCT pullback and lower error compared with conventional analysis.
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tct 386 Cut Plane analysis a new method of three dimensional oct rendering for side branch ostial assessment from a main vessel pullback
Journal of the American College of Cardiology, 2014Co-Authors: Antonios Karanasos, Nienke S Van Ditzhuijzen, Jurgen Ligthart, Nicolas M Van Mieghem, Robertjan Van Geuns, Peter De Jaegere, Felix Zijlstra, Johan H C Reiber, Evelyn RegarAbstract:In the assessment of coronary bifurcations, evaluation of side branch (SB) ostia by an optical coherence tomography (OCT) pullback performed in the main branch(MB) could speed up lesion evaluation. This assessment can be performed through dedicated software that renders the imaged segment in 3-D and
George S Athwal - One of the best experts on this subject based on the ideXlab platform.
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comparison of humeral head osteotomy using anatomic and guide assisted Cuts
Orthopaedic Proceedings, 2018Co-Authors: E West, Nikolas K Knowles, Louis M Ferreira, George S AthwalAbstract:Shoulder arthroplasty is used to treat osteoarthritis, post-traumatic arthritis, and avascular necrosis. Modular components allow for natural variability in shoulder anatomy, including retroversion and head-neck angles. Surgical options include anatomic or guide-assisted Cut at a fixed retroversion and head-neck angle. The purpose of this study was to determine the variability between head height (HH) and anteroposterior (AP) and superoinferior (SI) diameters using anatomic and guide-assisted humeral head Cuts.Computed tomography scans of 10 cadaveric shoulder specimens (5 male, 5 female) were converted to 3D models. An anatomic humeral head Cut Plane was placed at the anatomic head–neck junction maintaining the posterior cuff insertion for all shoulders by a fellowship trained shoulder surgeon. Cut Planes were generated for standard implant head neck angles (125°,130°,135°, and 140°) and retroversion angles (20°,30°, and 40°) in commercial Cutting guides, for a combination of 12 repeated Cut conditions p...
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comparison of humeral head osteotomy using anatomic and guide assisted Cuts
Journal of Bone and Joint Surgery-british Volume, 2016Co-Authors: E West, Nikolas K Knowles, Louis M Ferreira, George S AthwalAbstract:Shoulder arthroplasty is used to treat osteoarthritis, post-traumatic arthritis, and avascular necrosis. Modular components allow for natural variability in shoulder anatomy, including retroversion and head-neck angles. Surgical options include anatomic or guide-assisted Cut at a fixed retroversion and head-neck angle. The purpose of this study was to determine the variability between head height (HH) and anteroposterior (AP) and superoinferior (SI) diameters using anatomic and guide-assisted humeral head Cuts. Computed tomography scans of 10 cadaveric shoulder specimens (5 male, 5 female) were converted to 3D models. An anatomic humeral head Cut Plane was placed at the anatomic head–neck junction maintaining the posterior cuff insertion for all shoulders by a fellowship trained shoulder surgeon. Cut Planes were generated for standard implant head neck angles (125°,130°,135°, and 140°) and retroversion angles (20°,30°, and 40°) in commercial Cutting guides, for a combination of 12 repeated Cut conditions per specimen. The humeral HH and the head diameter were measured in the AP and the SI Planes for anatomic and guide-assisted osteotomy Planes. Differences were compared using a separate two-way repeated measures ANOVA for each dependent variable. Guide-assisted Cuts showed no significant effect on HH due to head-neck (p=0.205) or retroversion angles (p=0.190). These results persisted by gender (male: head-neck p=0.659 and retroversion p=0.386; female: head-neck p=0.204 and retroversion p=0.190). SI diameter increased by 1.3 mm with increasing head-neck angle (p For patients whose natural anatomy falls outside the range of the commercial Cut guides, templated resection may result in deviation from natural humeral head dimensions. Due to the large variability in anatomic retroversion and head-neck angles in the subjects of this study, further study with a larger sample size is needed to investigate observed trends. These preliminary results have implications for manufacturers to create guides to represent a larger segment of the population, and surgeons9 intra-operative choice.
Peter De Jaegere - One of the best experts on this subject based on the ideXlab platform.
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a novel method to assess coronary artery bifurcations by oct Cut Plane analysis for side branch ostial assessment from a main vessel pullback
European Journal of Echocardiography, 2015Co-Authors: Antonios Karanasos, Nienke S Van Ditzhuijzen, Jurgen Ligthart, Karen Witberg, Nicolas M Van Mieghem, Robertjan Van Geuns, Peter De Jaegere, Felix Zijlstra, Johan H C Reiber, Evelyn RegarAbstract:Aims In coronary bifurcations assessment, evaluation of side-branch (SB) ostia by an optical coherence tomography (OCT) pullback performed in the main branch (MB) could speed up lesion evaluation and minimize contrast volume. Dedicated software that reconstructs the cross-sections perpendicular to the SB centreline could improve this assessment. We aimed to validate a new method for assessing the SB ostium from an OCT pullback performed in the MB. Methods and results Thirty-one sets of frequency-domain OCT pullbacks from 28 patients, both from the MB and the SB of a coronary artery bifurcation were analysed. Measurements of the SB ostium from the SB pullback were used as a reference. Measurements of the SB ostium from the MB pullback were then performed in a laboratory setting by (i) conventional analysis and (ii) Cut-Plane analysis, and the measurement error for each analysis was estimated. Correlations of SB ostium measurements acquired from the MB pullback in comparison with reference measurements acquired from the SB pullback were higher with Cut-Plane analysis compared with conventional analysis, albeit not reaching statistical significance (area: r Cut-Plane = 0.927 vs. r conventional = 0.870, P = 0.256; mean diameter: r Cut-Plane = 0.918 vs. r conventional = 0.788, P = 0.056; minimum diameter: r Cut-Plane = 0.841 vs. r conventional = 0.812, P = 0.734; maximum diameter: r Cut-Plane = 0.770 vs. r conventional = 0.635, P = 0.316). Cut-Plane analysis was associated with lower absolute error than conventional analysis (area: 0.56 ± 0.45, vs. 1.50 ± 1.31 mm2, P < 0.001; mean diameter: 0.18 ± 0.14 vs. 0.44 ± 0.30 mm, P < 0.001). Conclusion Measurements of SB ostium performed in a laboratory setting by Cut-Plane analysis of an OCT pullback of the main branch have high correlation with reference measurements performed in a SB OCT pullback and lower error compared with conventional analysis.
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tct 386 Cut Plane analysis a new method of three dimensional oct rendering for side branch ostial assessment from a main vessel pullback
Journal of the American College of Cardiology, 2014Co-Authors: Antonios Karanasos, Nienke S Van Ditzhuijzen, Jurgen Ligthart, Nicolas M Van Mieghem, Robertjan Van Geuns, Peter De Jaegere, Felix Zijlstra, Johan H C Reiber, Evelyn RegarAbstract:In the assessment of coronary bifurcations, evaluation of side branch (SB) ostia by an optical coherence tomography (OCT) pullback performed in the main branch(MB) could speed up lesion evaluation. This assessment can be performed through dedicated software that renders the imaged segment in 3-D and
