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Michael S Conte - One of the best experts on this subject based on the ideXlab platform.
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a systematic review and meta analysis of revascularization outcomes of infrainguinal chronic limb threatening ischemia
Journal of Vascular Surgery, 2019Co-Authors: Jehad Almasri, Michael S Conte, Larry J Prokop, A W Bradbury, Jayanth Adusumalli, Sumaya Lakis, Mouaz Alsawas, Philippe Kolh, Hassan M MuradAbstract:Abstract Background The optimal strategy for revascularization in infrainguinal chronic limb-threatening ischemia (CLTI) remains debatable. Comparative trials are scarce, and daily decisions are often made using anecdotal or low-quality evidence. Methods We searched multiple databases through May 7, 2017, for prospective studies with at least 1-year follow-up that evaluated patient-relevant outcomes of infrainguinal revascularization procedures in adults with CLTI. Independent pairs of reviewers selected articles and extracted data. Random-effects meta-analysis was used to pool outcomes across studies. Results We included 44 studies that enrolled 8602 patients. Periprocedural outcomes (mortality, amputation, major adverse cardiac events) were similar across treatment modalities. Overall, patients with infrapopliteal disease had higher patency rates of great saphenous Vein graft at 1 and 2 years (primary: 87%, 78%; secondary: 94%, 87%, respectively) compared with all other interventions. Prosthetic Bypass outcomes were notably inferior to Vein Bypass in terms of amputation and patency outcomes, especially for below knee targets at 2 years and beyond. Drug-eluting stents demonstrated improved patency over bare-metal stents in infrapopliteal arteries (primary patency: 73% vs 50% at 1 year), and was at least comparable to balloon angioplasty (66% primary patency). Survival, major amputation, and amputation-free survival at 2 years were broadly similar between endovascular interventions and Vein Bypass, with prosthetic Bypass having higher rates of limb loss. Overall, the included studies were at moderate to high risk of bias and the quality of evidence was low. Conclusions There are major limitations in the current state of evidence guiding treatment decisions in CLTI, particularly for severe anatomic patterns of disease treated via endovascular means. Periprocedural (30-day) mortality, amputation, and major adverse cardiac events are broadly similar across modalities. Patency rates are highest for saphenous Vein Bypass, whereas both patency and limb salvage are markedly inferior for prosthetic grafting to below the knee targets. Among endovascular interventions, percutaneous transluminal angioplasty and drug-eluting stents appear comparable for focal infrapopliteal disease, although no studies included long segment tibial lesions. Heterogeneity in patient risk, severity of limb threat, and anatomy treated renders direct comparison of outcomes from the current literature challenging. Future studies should incorporate both limb severity and anatomic staging to best guide clinical decision making in CLTI.
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multi contrast high spatial resolution black blood inner volume three dimensional fast spin echo mr imaging in peripheral Vein Bypass grafts
International Journal of Cardiovascular Imaging, 2010Co-Authors: Frank J Rybicki, Dimitris Mitsouras, Christopher D Owens, Amanda G Whitmore, Marie Gerhardherman, Nichole Wake, Tianxi Cai, Qian M Zhou, Michael S ConteAbstract:The purpose of this study is to primarily evaluate the lumen area and secondarily evaluate wall area measurements of in vivo lower extremity peripheral Vein Bypass grafts patients using high spatial resolution, limited field of view, cardiac gated, black blood inner volume three-dimensional fast spin echo MRI. Fifteen LE-PVBG patients prospectively underwent ultrasound followed by T1-weighted and T2-weighted magnetic resonance (MR) imaging. Lumen and vessel wall areas were measured by direct planimetry. For graft lumen areas, T1- and T2-weighted measurements were compared with ultrasound. For vessel wall areas, differences between T1- and T2-weighted measurements were evaluated. There was no significant difference between ultrasound and MR lumen measurements, reflecting minimal MR blood suppression artifact. Graft wall area measured from T1-weighted images was significantly larger than that measured from T2-weighted images (P < 0.001). The mean of the ratio of T1- versus T2-weighted vessel wall areas was 1.59 (95% CI: 1.48–1.69). The larger wall area measured on T1-weighted images was due to a significantly larger outer vessel wall boundary. Very high spatial resolution LE-PVBG vessel wall MR imaging can be performed in vivo, enabling accurate measurements of lumen and vessel wall areas and discerning differences in those measures between different tissue contrast weightings. Vessel wall area differences suggest that LE-PVBG vessel wall tissues produce distinct signal characteristics under T1 and T2 MR contrast weightings.
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technical factors in lower extremity Vein Bypass surgery how can we improve outcomes
Seminars in Vascular Surgery, 2009Co-Authors: Michael S ConteAbstract:Lower-extremity Vein Bypass surgery has been a standard operation in the armamentarium of vascular surgeons for more than 4 decades. Yet there remains surprising heterogeneity in the utilization, techniques, and outcomes associated with this procedure in current practice. Despite improvements in surgical technique and careful postoperative surveillance, Vein graft failure remains a significant clinical problem affecting up to 50% of patients within 5 years. Experience, clinical judgment, creativity, and technical precision are required to optimize long-term results. Many factors, including patient-specific comorbidities, and variable biologic responses in the venous conduit, influence the ultimate outcome. Technical factors, however, play a dominant role in determining clinical success. Multiple single-center reports, and more recent multicenter trials, have clearly demonstrated that conduit selection and quality is the most critical element. An adequate caliber (≥3.5 mm), good quality great saphenous Vein is the optimal graft for infrainguinal Bypass. Contralateral great saphenous Vein, arm Vein, and lesser saphenous Vein are the next most desirable conduits. Graft configuration (reversed, nonreversed, or in situ) appears to have little influence on outcomes per se. Shorter grafts have improved patency. Inflow can be improved by surgical or endovascular means if necessary, and distal-origin grafts perform as well as those originating from the common femoral artery. The selected outflow vessel should supply unimpeded runoff to the foot, conserve conduit length, and allow for adequate soft-tissue coverage of the graft and a simplified surgical exposure. This review summarizes the data linking technical factors with graft patency, highlighting the importance of surgical judgment and operative planning in the current practice of infrainguinal Bypass surgery.
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in vivo human lower extremity saphenous Vein Bypass grafts manifest flow mediated vasodilation
Journal of Vascular Surgery, 2009Co-Authors: Christopher D Owens, Michael S Conte, Marie Gerhardherman, Nicole Wake, Joshua A BeckmanAbstract:Objective As in arteries, venous endothelium modulates vessel homeostasis and tone. The effect of an arterialized environment on venous endothelial function remains poorly understood. In particular, regulation of saphenous Vein graft (SVG) blood flow and lumen caliber remains undefined. We hypothesized that mature SVGs would exhibit endothelium-dependent, flow-mediated vasodilation (FMD). We further hypothesized that endothelium-derived nitric oxide (NO) was an important mediator. Methods Patients with femoral to popliteal artery SVGs that had maintained primary patency and were at least 1 year from surgery were enrolled. High-resolution, B-mode ultrasound scans were used to measure Vein graft diameter before and 1 minute after reactive hyperemia (RH) to determine FMD. RH was created through application of 220 mm Hg to the calf for 5 minutes with a sphygmomanometric cuff. After a 10-minute recovery period, nitroglycerin-mediated, endothelium-independent vasodilation was measured 3 minutes after administration of nitroglycerin 0.4 mg sublingually. Brachial artery FMD was determined by validated techniques. L-N G monomethyl arginine (L-NMMA; 1 mg/kg infusion over 10 minutes) was used in a subset of patients (n = 6) to competitively inhibit endothelial NO synthase. Results Nineteen subjects were enrolled. The median age of the SVGs was 34.6 (21.0-49.7) months. SVG flow-mediated, endothelium-dependent vasodilation was measured at 5.28% ± 3.1% mean change in lumen diameter (range, 1.99%-9.36%; P P P = .0088) and attenuated brachial artery FMD (7.54% ± 1.0% vs 5.7 ± 1.4; P = .05). Conclusion SVGs manifest flow-mediated, endothelium-dependent, and nitroglycerin-mediated endothelium-independent vasodilation. Vein graft endothelium-dependent FMD is likely mediated by NO. Further investigation will be required to determine the role of endothelial function in Vein graft patency.
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validation of the piii cli risk score for the prediction of amputation free survival in patients undergoing infrainguinal autogenous Vein Bypass for critical limb ischemia
Journal of Vascular Surgery, 2009Co-Authors: Andres Schanzer, Philip P Goodney, Mohammad H Eslami, Jack L Cronenwett, Louis M Messina, Michael S ConteAbstract:Objective The PREVENT III (PIII) critical limb ischemia (CLI) risk score is a simple, published tool derived from the PIII randomized clinical trial that can be used for estimating amputation-free survival (AFS) in CLI patients considered for infrainguinal Bypass (IB). The current study sought to validate this risk stratification model using data from the prospectively collected Vascular Study Group of Northern New England (VSGNNE). Method We calculated the PIII CLI risk score for 1166 patients undergoing IB with autogenous Vein by 59 surgeons at 11 hospitals between January 1, 2003, and December 31, 2007. Points (pts) were assigned to each patient for the presence of dialysis (4 pts), tissue loss (3 pts), age ≥75 (2 pts), and coronary artery disease (CAD) (1 pt). Baseline hematocrit was not included due to a large proportion of missing values. Total scores were used to stratify each patient into low-risk (≤3 pts), med-risk (4-7 pts), and high-risk (≥8 pts) categories. The Kaplan-Meier method was used to calculate AFS for the three risk groups. Log-rank test was used for intergroup comparisons. To assess validation, comparison to the PIII derivation and validation sets was performed. Result Stratification of the VSGNNE patients by risk category yielded three significantly different estimates for 1-year AFS (86.4%, 74.0%, and 56.1%, for low-, med-, and high-risk groups). Intergroup comparison demonstrated precise discrimination ( P Conclusion The PIII CLI risk score has now been both internally and externally validated by testing it against the outcomes of 3286 CLI patients who underwent autogenous Vein Bypass at 94 institutions by a diverse array of physicians (three independent cohorts of patients). This tool provides a simple and reliable method to risk stratify CLI patients being considered for IB. At initial consultation, calculation of the PIII CLI risk score can reliably stratify patients according to their risk of death or major amputation at 1 year.
Christopher D Owens - One of the best experts on this subject based on the ideXlab platform.
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multi contrast high spatial resolution black blood inner volume three dimensional fast spin echo mr imaging in peripheral Vein Bypass grafts
International Journal of Cardiovascular Imaging, 2010Co-Authors: Frank J Rybicki, Dimitris Mitsouras, Christopher D Owens, Amanda G Whitmore, Marie Gerhardherman, Nichole Wake, Tianxi Cai, Qian M Zhou, Michael S ConteAbstract:The purpose of this study is to primarily evaluate the lumen area and secondarily evaluate wall area measurements of in vivo lower extremity peripheral Vein Bypass grafts patients using high spatial resolution, limited field of view, cardiac gated, black blood inner volume three-dimensional fast spin echo MRI. Fifteen LE-PVBG patients prospectively underwent ultrasound followed by T1-weighted and T2-weighted magnetic resonance (MR) imaging. Lumen and vessel wall areas were measured by direct planimetry. For graft lumen areas, T1- and T2-weighted measurements were compared with ultrasound. For vessel wall areas, differences between T1- and T2-weighted measurements were evaluated. There was no significant difference between ultrasound and MR lumen measurements, reflecting minimal MR blood suppression artifact. Graft wall area measured from T1-weighted images was significantly larger than that measured from T2-weighted images (P < 0.001). The mean of the ratio of T1- versus T2-weighted vessel wall areas was 1.59 (95% CI: 1.48–1.69). The larger wall area measured on T1-weighted images was due to a significantly larger outer vessel wall boundary. Very high spatial resolution LE-PVBG vessel wall MR imaging can be performed in vivo, enabling accurate measurements of lumen and vessel wall areas and discerning differences in those measures between different tissue contrast weightings. Vessel wall area differences suggest that LE-PVBG vessel wall tissues produce distinct signal characteristics under T1 and T2 MR contrast weightings.
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in vivo human lower extremity saphenous Vein Bypass grafts manifest flow mediated vasodilation
Journal of Vascular Surgery, 2009Co-Authors: Christopher D Owens, Michael S Conte, Marie Gerhardherman, Nicole Wake, Joshua A BeckmanAbstract:Objective As in arteries, venous endothelium modulates vessel homeostasis and tone. The effect of an arterialized environment on venous endothelial function remains poorly understood. In particular, regulation of saphenous Vein graft (SVG) blood flow and lumen caliber remains undefined. We hypothesized that mature SVGs would exhibit endothelium-dependent, flow-mediated vasodilation (FMD). We further hypothesized that endothelium-derived nitric oxide (NO) was an important mediator. Methods Patients with femoral to popliteal artery SVGs that had maintained primary patency and were at least 1 year from surgery were enrolled. High-resolution, B-mode ultrasound scans were used to measure Vein graft diameter before and 1 minute after reactive hyperemia (RH) to determine FMD. RH was created through application of 220 mm Hg to the calf for 5 minutes with a sphygmomanometric cuff. After a 10-minute recovery period, nitroglycerin-mediated, endothelium-independent vasodilation was measured 3 minutes after administration of nitroglycerin 0.4 mg sublingually. Brachial artery FMD was determined by validated techniques. L-N G monomethyl arginine (L-NMMA; 1 mg/kg infusion over 10 minutes) was used in a subset of patients (n = 6) to competitively inhibit endothelial NO synthase. Results Nineteen subjects were enrolled. The median age of the SVGs was 34.6 (21.0-49.7) months. SVG flow-mediated, endothelium-dependent vasodilation was measured at 5.28% ± 3.1% mean change in lumen diameter (range, 1.99%-9.36%; P P P = .0088) and attenuated brachial artery FMD (7.54% ± 1.0% vs 5.7 ± 1.4; P = .05). Conclusion SVGs manifest flow-mediated, endothelium-dependent, and nitroglycerin-mediated endothelium-independent vasodilation. Vein graft endothelium-dependent FMD is likely mediated by NO. Further investigation will be required to determine the role of endothelial function in Vein graft patency.
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in vivo differentiation of two vessel wall layers in lower extremity peripheral Vein Bypass grafts application of high resolution inner volume black blood 3d fse
Magnetic Resonance in Medicine, 2009Co-Authors: Dimitris Mitsouras, Christopher D Owens, Michael S Conte, Hale Ersoy, Mark A Creager, Frank J RybickiAbstract:Lower extremity peripheral Vein Bypass grafts (LE-PVBG) imaged with high-resolution black blood three-dimensional (3D) inner-volume (IV) fast spin echo (FSE) MRI at 1.5 Tesla possess a two-layer appearance in T1W images while only the inner layer appears visible in the corresponding T2W images. This study quantifies this difference in six patients imaged 6 months after implantation, and attributes the difference to the T2 relaxation rates of vessel wall tissues measured ex vivo in two specimens with histologic correlation. The visual observation of two LE-PVBG vessel wall components imaged in vivo is confirmed to be significant (P < 0.0001), with a mean vessel wall area difference of 6.8 ± 2.7 mm2 between contrasts, and a ratio of T1W to T2W vessel wall area of 1.67 ± 0.28. The difference is attributed to a significantly (P < 0.0001) shorter T2 relaxation in the adventitia (T2 = 52.6 ± 3.5 ms) compared with the neointima/media (T2 = 174.7 ± 12.1 ms). Notably, adventitial tissue exhibits biexponential T2 signal decay (P < 0.0001 vs monoexponential). Our results suggest that high-resolution black blood 3D IV-FSE can be useful for studying the biology of Bypass graft wall maturation and pathophysiology in vivo, by enabling independent visualization of the relative remodeling of the neointima/media and adventitia. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc.
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in vivo differentiation of two vessel wall layers in lower extremity peripheral Vein Bypass grafts application of high resolution inner volume black blood 3d fse
Magnetic Resonance in Medicine, 2009Co-Authors: Dimitris Mitsouras, Christopher D Owens, Michael S Conte, Hale Ersoy, Mark A Creager, Frank J RybickiAbstract:Lower extremity peripheral Vein Bypass grafts (LE-PVBG) imaged with high-resolution black blood three-dimensional (3D) inner-volume (IV) fast spin echo (FSE) MRI at 1.5 Tesla possess a two-layer appearance in T1W images while only the inner layer appears visible in the corresponding T2W images. This study quantifies this difference in six patients imaged 6 months after implantation, and attributes the difference to the T(2) relaxation rates of vessel wall tissues measured ex vivo in two specimens with histologic correlation. The visual observation of two LE-PVBG vessel wall components imaged in vivo is confirmed to be significant (P < 0.0001), with a mean vessel wall area difference of 6.8 +/- 2.7 mm(2) between contrasts, and a ratio of T1W to T2W vessel wall area of 1.67 +/- 0.28. The difference is attributed to a significantly (P < 0.0001) shorter T(2) relaxation in the adventitia (T(2) = 52.6 +/- 3.5 ms) compared with the neointima/media (T(2) = 174.7 +/- 12.1 ms). Notably, adventitial tissue exhibits biexponential T(2) signal decay (P < 0.0001 vs monoexponential). Our results suggest that high-resolution black blood 3D IV-FSE can be useful for studying the biology of Bypass graft wall maturation and pathophysiology in vivo, by enabling independent visualization of the relative remodeling of the neointima/media and adventitia.
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lower extremity peripheral Vein Bypass graft wall thickness changes demonstrated at 1 and 6 months after surgery with ultra high spatial resolution black blood inner volume three dimensional fast spin echo magnetic resonance imaging
International Journal of Cardiovascular Imaging, 2008Co-Authors: Frank J Rybicki, Dimitris Mitsouras, Robert V Mulkern, Christopher D Owens, Hale Ersoy, Amanda G Whitmore, Mark A Creager, Michael S ConteAbstract:Objective To demonstrate lower extremity peripheral Vein Bypass graft wall thickness changes over time in a patient using very high spatial resolution cardiac gated, black blood inner volume three-dimensional (3D) fast spin echo (FSE) magnetic resonance imaging (MRI). Case report A 52-year-old diabetic man with a history of hyperlipidemia underwent uncomplicated Bypass grafting for an asymptomatic 5.2 cm popliteal artery aneurysm using reversed great saphenous Vein. A segment of the Bypass graft was studied at 1 and 6 months after surgery with cardiac gated inner volume 3D-FSE imaging with non-interpolated 0.195 mm3 voxel volumes (0.3125 × 0.3125 × 2 mm). T1- and T2-weighted images were acquired in 10 min per contrast weighting. Graft imaging at one month after implantation illustrates expansion of the outer wall of the graft that partially resolves 5 months later. Conclusion In this patient, expansion of the lower extremity peripheral Bypass graft wall can be characterized in clinical scan times with a 3D-FSE MRI protocol using highly selective inner volume excitation followed by non-selective refocusing pulses. The resulting 3D images can potentially be used to study the biology of the vessel wall.
Dimitris Mitsouras - One of the best experts on this subject based on the ideXlab platform.
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multi contrast high spatial resolution black blood inner volume three dimensional fast spin echo mr imaging in peripheral Vein Bypass grafts
International Journal of Cardiovascular Imaging, 2010Co-Authors: Frank J Rybicki, Dimitris Mitsouras, Christopher D Owens, Amanda G Whitmore, Marie Gerhardherman, Nichole Wake, Tianxi Cai, Qian M Zhou, Michael S ConteAbstract:The purpose of this study is to primarily evaluate the lumen area and secondarily evaluate wall area measurements of in vivo lower extremity peripheral Vein Bypass grafts patients using high spatial resolution, limited field of view, cardiac gated, black blood inner volume three-dimensional fast spin echo MRI. Fifteen LE-PVBG patients prospectively underwent ultrasound followed by T1-weighted and T2-weighted magnetic resonance (MR) imaging. Lumen and vessel wall areas were measured by direct planimetry. For graft lumen areas, T1- and T2-weighted measurements were compared with ultrasound. For vessel wall areas, differences between T1- and T2-weighted measurements were evaluated. There was no significant difference between ultrasound and MR lumen measurements, reflecting minimal MR blood suppression artifact. Graft wall area measured from T1-weighted images was significantly larger than that measured from T2-weighted images (P < 0.001). The mean of the ratio of T1- versus T2-weighted vessel wall areas was 1.59 (95% CI: 1.48–1.69). The larger wall area measured on T1-weighted images was due to a significantly larger outer vessel wall boundary. Very high spatial resolution LE-PVBG vessel wall MR imaging can be performed in vivo, enabling accurate measurements of lumen and vessel wall areas and discerning differences in those measures between different tissue contrast weightings. Vessel wall area differences suggest that LE-PVBG vessel wall tissues produce distinct signal characteristics under T1 and T2 MR contrast weightings.
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in vivo differentiation of two vessel wall layers in lower extremity peripheral Vein Bypass grafts application of high resolution inner volume black blood 3d fse
Magnetic Resonance in Medicine, 2009Co-Authors: Dimitris Mitsouras, Christopher D Owens, Michael S Conte, Hale Ersoy, Mark A Creager, Frank J RybickiAbstract:Lower extremity peripheral Vein Bypass grafts (LE-PVBG) imaged with high-resolution black blood three-dimensional (3D) inner-volume (IV) fast spin echo (FSE) MRI at 1.5 Tesla possess a two-layer appearance in T1W images while only the inner layer appears visible in the corresponding T2W images. This study quantifies this difference in six patients imaged 6 months after implantation, and attributes the difference to the T2 relaxation rates of vessel wall tissues measured ex vivo in two specimens with histologic correlation. The visual observation of two LE-PVBG vessel wall components imaged in vivo is confirmed to be significant (P < 0.0001), with a mean vessel wall area difference of 6.8 ± 2.7 mm2 between contrasts, and a ratio of T1W to T2W vessel wall area of 1.67 ± 0.28. The difference is attributed to a significantly (P < 0.0001) shorter T2 relaxation in the adventitia (T2 = 52.6 ± 3.5 ms) compared with the neointima/media (T2 = 174.7 ± 12.1 ms). Notably, adventitial tissue exhibits biexponential T2 signal decay (P < 0.0001 vs monoexponential). Our results suggest that high-resolution black blood 3D IV-FSE can be useful for studying the biology of Bypass graft wall maturation and pathophysiology in vivo, by enabling independent visualization of the relative remodeling of the neointima/media and adventitia. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc.
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in vivo differentiation of two vessel wall layers in lower extremity peripheral Vein Bypass grafts application of high resolution inner volume black blood 3d fse
Magnetic Resonance in Medicine, 2009Co-Authors: Dimitris Mitsouras, Christopher D Owens, Michael S Conte, Hale Ersoy, Mark A Creager, Frank J RybickiAbstract:Lower extremity peripheral Vein Bypass grafts (LE-PVBG) imaged with high-resolution black blood three-dimensional (3D) inner-volume (IV) fast spin echo (FSE) MRI at 1.5 Tesla possess a two-layer appearance in T1W images while only the inner layer appears visible in the corresponding T2W images. This study quantifies this difference in six patients imaged 6 months after implantation, and attributes the difference to the T(2) relaxation rates of vessel wall tissues measured ex vivo in two specimens with histologic correlation. The visual observation of two LE-PVBG vessel wall components imaged in vivo is confirmed to be significant (P < 0.0001), with a mean vessel wall area difference of 6.8 +/- 2.7 mm(2) between contrasts, and a ratio of T1W to T2W vessel wall area of 1.67 +/- 0.28. The difference is attributed to a significantly (P < 0.0001) shorter T(2) relaxation in the adventitia (T(2) = 52.6 +/- 3.5 ms) compared with the neointima/media (T(2) = 174.7 +/- 12.1 ms). Notably, adventitial tissue exhibits biexponential T(2) signal decay (P < 0.0001 vs monoexponential). Our results suggest that high-resolution black blood 3D IV-FSE can be useful for studying the biology of Bypass graft wall maturation and pathophysiology in vivo, by enabling independent visualization of the relative remodeling of the neointima/media and adventitia.
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lower extremity peripheral Vein Bypass graft wall thickness changes demonstrated at 1 and 6 months after surgery with ultra high spatial resolution black blood inner volume three dimensional fast spin echo magnetic resonance imaging
International Journal of Cardiovascular Imaging, 2008Co-Authors: Frank J Rybicki, Dimitris Mitsouras, Robert V Mulkern, Christopher D Owens, Hale Ersoy, Amanda G Whitmore, Mark A Creager, Michael S ConteAbstract:Objective To demonstrate lower extremity peripheral Vein Bypass graft wall thickness changes over time in a patient using very high spatial resolution cardiac gated, black blood inner volume three-dimensional (3D) fast spin echo (FSE) magnetic resonance imaging (MRI). Case report A 52-year-old diabetic man with a history of hyperlipidemia underwent uncomplicated Bypass grafting for an asymptomatic 5.2 cm popliteal artery aneurysm using reversed great saphenous Vein. A segment of the Bypass graft was studied at 1 and 6 months after surgery with cardiac gated inner volume 3D-FSE imaging with non-interpolated 0.195 mm3 voxel volumes (0.3125 × 0.3125 × 2 mm). T1- and T2-weighted images were acquired in 10 min per contrast weighting. Graft imaging at one month after implantation illustrates expansion of the outer wall of the graft that partially resolves 5 months later. Conclusion In this patient, expansion of the lower extremity peripheral Bypass graft wall can be characterized in clinical scan times with a 3D-FSE MRI protocol using highly selective inner volume excitation followed by non-selective refocusing pulses. The resulting 3D images can potentially be used to study the biology of the vessel wall.
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high resolution peripheral Vein Bypass graft wall studies using high sampling efficiency inner volume 3d fse
Magnetic Resonance in Medicine, 2008Co-Authors: Dimitris Mitsouras, Robert V Mulkern, Christopher D Owens, Michael S Conte, Hale ErsoyAbstract:A 3D inner-volume fast spin echo (3D IV-FSE) sequence was developed for ECG-gated, black-blood, T1- and T2-weighted vessel wall imaging of peripheral Vein Bypass grafts (PVBG). The sequence utilizes nonselective refocusing excitations to minimize echo spacings and a highly selective IV excitation scheme to minimize the need for oversampling of z-encode slice selections. The method was tested in eight PVBG patients who also underwent 2D FSE graft imaging. High-quality 3D imaging was achieved in all subjects, with significant spatial resolution and volume coverage gains compared to the more conventional 2D FSE sequences normalized for signal-to-noise ratios (SNRs) and scan times. Compared to previously proposed 3D IV-FSE methods, nonselective refocusing resulted in a more than 20% FSE echo train sampling efficiency increase while the use of highly selective IV excitation resulted in a 30% improvement in slice oversampling efficiency. Magn Reson Med, 2008. © 2008 Wiley-Liss, Inc.
Hale Ersoy - One of the best experts on this subject based on the ideXlab platform.
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in vivo differentiation of two vessel wall layers in lower extremity peripheral Vein Bypass grafts application of high resolution inner volume black blood 3d fse
Magnetic Resonance in Medicine, 2009Co-Authors: Dimitris Mitsouras, Christopher D Owens, Michael S Conte, Hale Ersoy, Mark A Creager, Frank J RybickiAbstract:Lower extremity peripheral Vein Bypass grafts (LE-PVBG) imaged with high-resolution black blood three-dimensional (3D) inner-volume (IV) fast spin echo (FSE) MRI at 1.5 Tesla possess a two-layer appearance in T1W images while only the inner layer appears visible in the corresponding T2W images. This study quantifies this difference in six patients imaged 6 months after implantation, and attributes the difference to the T(2) relaxation rates of vessel wall tissues measured ex vivo in two specimens with histologic correlation. The visual observation of two LE-PVBG vessel wall components imaged in vivo is confirmed to be significant (P < 0.0001), with a mean vessel wall area difference of 6.8 +/- 2.7 mm(2) between contrasts, and a ratio of T1W to T2W vessel wall area of 1.67 +/- 0.28. The difference is attributed to a significantly (P < 0.0001) shorter T(2) relaxation in the adventitia (T(2) = 52.6 +/- 3.5 ms) compared with the neointima/media (T(2) = 174.7 +/- 12.1 ms). Notably, adventitial tissue exhibits biexponential T(2) signal decay (P < 0.0001 vs monoexponential). Our results suggest that high-resolution black blood 3D IV-FSE can be useful for studying the biology of Bypass graft wall maturation and pathophysiology in vivo, by enabling independent visualization of the relative remodeling of the neointima/media and adventitia.
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in vivo differentiation of two vessel wall layers in lower extremity peripheral Vein Bypass grafts application of high resolution inner volume black blood 3d fse
Magnetic Resonance in Medicine, 2009Co-Authors: Dimitris Mitsouras, Christopher D Owens, Michael S Conte, Hale Ersoy, Mark A Creager, Frank J RybickiAbstract:Lower extremity peripheral Vein Bypass grafts (LE-PVBG) imaged with high-resolution black blood three-dimensional (3D) inner-volume (IV) fast spin echo (FSE) MRI at 1.5 Tesla possess a two-layer appearance in T1W images while only the inner layer appears visible in the corresponding T2W images. This study quantifies this difference in six patients imaged 6 months after implantation, and attributes the difference to the T2 relaxation rates of vessel wall tissues measured ex vivo in two specimens with histologic correlation. The visual observation of two LE-PVBG vessel wall components imaged in vivo is confirmed to be significant (P < 0.0001), with a mean vessel wall area difference of 6.8 ± 2.7 mm2 between contrasts, and a ratio of T1W to T2W vessel wall area of 1.67 ± 0.28. The difference is attributed to a significantly (P < 0.0001) shorter T2 relaxation in the adventitia (T2 = 52.6 ± 3.5 ms) compared with the neointima/media (T2 = 174.7 ± 12.1 ms). Notably, adventitial tissue exhibits biexponential T2 signal decay (P < 0.0001 vs monoexponential). Our results suggest that high-resolution black blood 3D IV-FSE can be useful for studying the biology of Bypass graft wall maturation and pathophysiology in vivo, by enabling independent visualization of the relative remodeling of the neointima/media and adventitia. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc.
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lower extremity peripheral Vein Bypass graft wall thickness changes demonstrated at 1 and 6 months after surgery with ultra high spatial resolution black blood inner volume three dimensional fast spin echo magnetic resonance imaging
International Journal of Cardiovascular Imaging, 2008Co-Authors: Frank J Rybicki, Dimitris Mitsouras, Robert V Mulkern, Christopher D Owens, Hale Ersoy, Amanda G Whitmore, Mark A Creager, Michael S ConteAbstract:Objective To demonstrate lower extremity peripheral Vein Bypass graft wall thickness changes over time in a patient using very high spatial resolution cardiac gated, black blood inner volume three-dimensional (3D) fast spin echo (FSE) magnetic resonance imaging (MRI). Case report A 52-year-old diabetic man with a history of hyperlipidemia underwent uncomplicated Bypass grafting for an asymptomatic 5.2 cm popliteal artery aneurysm using reversed great saphenous Vein. A segment of the Bypass graft was studied at 1 and 6 months after surgery with cardiac gated inner volume 3D-FSE imaging with non-interpolated 0.195 mm3 voxel volumes (0.3125 × 0.3125 × 2 mm). T1- and T2-weighted images were acquired in 10 min per contrast weighting. Graft imaging at one month after implantation illustrates expansion of the outer wall of the graft that partially resolves 5 months later. Conclusion In this patient, expansion of the lower extremity peripheral Bypass graft wall can be characterized in clinical scan times with a 3D-FSE MRI protocol using highly selective inner volume excitation followed by non-selective refocusing pulses. The resulting 3D images can potentially be used to study the biology of the vessel wall.
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high resolution peripheral Vein Bypass graft wall studies using high sampling efficiency inner volume 3d fse
Magnetic Resonance in Medicine, 2008Co-Authors: Dimitris Mitsouras, Robert V Mulkern, Christopher D Owens, Michael S Conte, Hale ErsoyAbstract:A 3D inner-volume fast spin echo (3D IV-FSE) sequence was developed for ECG-gated, black-blood, T1- and T2-weighted vessel wall imaging of peripheral Vein Bypass grafts (PVBG). The sequence utilizes nonselective refocusing excitations to minimize echo spacings and a highly selective IV excitation scheme to minimize the need for oversampling of z-encode slice selections. The method was tested in eight PVBG patients who also underwent 2D FSE graft imaging. High-quality 3D imaging was achieved in all subjects, with significant spatial resolution and volume coverage gains compared to the more conventional 2D FSE sequences normalized for signal-to-noise ratios (SNRs) and scan times. Compared to previously proposed 3D IV-FSE methods, nonselective refocusing resulted in a more than 20% FSE echo train sampling efficiency increase while the use of highly selective IV excitation resulted in a 30% improvement in slice oversampling efficiency. Magn Reson Med, 2008. © 2008 Wiley-Liss, Inc.
Frank J Rybicki - One of the best experts on this subject based on the ideXlab platform.
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multi contrast high spatial resolution black blood inner volume three dimensional fast spin echo mr imaging in peripheral Vein Bypass grafts
International Journal of Cardiovascular Imaging, 2010Co-Authors: Frank J Rybicki, Dimitris Mitsouras, Christopher D Owens, Amanda G Whitmore, Marie Gerhardherman, Nichole Wake, Tianxi Cai, Qian M Zhou, Michael S ConteAbstract:The purpose of this study is to primarily evaluate the lumen area and secondarily evaluate wall area measurements of in vivo lower extremity peripheral Vein Bypass grafts patients using high spatial resolution, limited field of view, cardiac gated, black blood inner volume three-dimensional fast spin echo MRI. Fifteen LE-PVBG patients prospectively underwent ultrasound followed by T1-weighted and T2-weighted magnetic resonance (MR) imaging. Lumen and vessel wall areas were measured by direct planimetry. For graft lumen areas, T1- and T2-weighted measurements were compared with ultrasound. For vessel wall areas, differences between T1- and T2-weighted measurements were evaluated. There was no significant difference between ultrasound and MR lumen measurements, reflecting minimal MR blood suppression artifact. Graft wall area measured from T1-weighted images was significantly larger than that measured from T2-weighted images (P < 0.001). The mean of the ratio of T1- versus T2-weighted vessel wall areas was 1.59 (95% CI: 1.48–1.69). The larger wall area measured on T1-weighted images was due to a significantly larger outer vessel wall boundary. Very high spatial resolution LE-PVBG vessel wall MR imaging can be performed in vivo, enabling accurate measurements of lumen and vessel wall areas and discerning differences in those measures between different tissue contrast weightings. Vessel wall area differences suggest that LE-PVBG vessel wall tissues produce distinct signal characteristics under T1 and T2 MR contrast weightings.
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in vivo differentiation of two vessel wall layers in lower extremity peripheral Vein Bypass grafts application of high resolution inner volume black blood 3d fse
Magnetic Resonance in Medicine, 2009Co-Authors: Dimitris Mitsouras, Christopher D Owens, Michael S Conte, Hale Ersoy, Mark A Creager, Frank J RybickiAbstract:Lower extremity peripheral Vein Bypass grafts (LE-PVBG) imaged with high-resolution black blood three-dimensional (3D) inner-volume (IV) fast spin echo (FSE) MRI at 1.5 Tesla possess a two-layer appearance in T1W images while only the inner layer appears visible in the corresponding T2W images. This study quantifies this difference in six patients imaged 6 months after implantation, and attributes the difference to the T2 relaxation rates of vessel wall tissues measured ex vivo in two specimens with histologic correlation. The visual observation of two LE-PVBG vessel wall components imaged in vivo is confirmed to be significant (P < 0.0001), with a mean vessel wall area difference of 6.8 ± 2.7 mm2 between contrasts, and a ratio of T1W to T2W vessel wall area of 1.67 ± 0.28. The difference is attributed to a significantly (P < 0.0001) shorter T2 relaxation in the adventitia (T2 = 52.6 ± 3.5 ms) compared with the neointima/media (T2 = 174.7 ± 12.1 ms). Notably, adventitial tissue exhibits biexponential T2 signal decay (P < 0.0001 vs monoexponential). Our results suggest that high-resolution black blood 3D IV-FSE can be useful for studying the biology of Bypass graft wall maturation and pathophysiology in vivo, by enabling independent visualization of the relative remodeling of the neointima/media and adventitia. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc.
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in vivo differentiation of two vessel wall layers in lower extremity peripheral Vein Bypass grafts application of high resolution inner volume black blood 3d fse
Magnetic Resonance in Medicine, 2009Co-Authors: Dimitris Mitsouras, Christopher D Owens, Michael S Conte, Hale Ersoy, Mark A Creager, Frank J RybickiAbstract:Lower extremity peripheral Vein Bypass grafts (LE-PVBG) imaged with high-resolution black blood three-dimensional (3D) inner-volume (IV) fast spin echo (FSE) MRI at 1.5 Tesla possess a two-layer appearance in T1W images while only the inner layer appears visible in the corresponding T2W images. This study quantifies this difference in six patients imaged 6 months after implantation, and attributes the difference to the T(2) relaxation rates of vessel wall tissues measured ex vivo in two specimens with histologic correlation. The visual observation of two LE-PVBG vessel wall components imaged in vivo is confirmed to be significant (P < 0.0001), with a mean vessel wall area difference of 6.8 +/- 2.7 mm(2) between contrasts, and a ratio of T1W to T2W vessel wall area of 1.67 +/- 0.28. The difference is attributed to a significantly (P < 0.0001) shorter T(2) relaxation in the adventitia (T(2) = 52.6 +/- 3.5 ms) compared with the neointima/media (T(2) = 174.7 +/- 12.1 ms). Notably, adventitial tissue exhibits biexponential T(2) signal decay (P < 0.0001 vs monoexponential). Our results suggest that high-resolution black blood 3D IV-FSE can be useful for studying the biology of Bypass graft wall maturation and pathophysiology in vivo, by enabling independent visualization of the relative remodeling of the neointima/media and adventitia.
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lower extremity peripheral Vein Bypass graft wall thickness changes demonstrated at 1 and 6 months after surgery with ultra high spatial resolution black blood inner volume three dimensional fast spin echo magnetic resonance imaging
International Journal of Cardiovascular Imaging, 2008Co-Authors: Frank J Rybicki, Dimitris Mitsouras, Robert V Mulkern, Christopher D Owens, Hale Ersoy, Amanda G Whitmore, Mark A Creager, Michael S ConteAbstract:Objective To demonstrate lower extremity peripheral Vein Bypass graft wall thickness changes over time in a patient using very high spatial resolution cardiac gated, black blood inner volume three-dimensional (3D) fast spin echo (FSE) magnetic resonance imaging (MRI). Case report A 52-year-old diabetic man with a history of hyperlipidemia underwent uncomplicated Bypass grafting for an asymptomatic 5.2 cm popliteal artery aneurysm using reversed great saphenous Vein. A segment of the Bypass graft was studied at 1 and 6 months after surgery with cardiac gated inner volume 3D-FSE imaging with non-interpolated 0.195 mm3 voxel volumes (0.3125 × 0.3125 × 2 mm). T1- and T2-weighted images were acquired in 10 min per contrast weighting. Graft imaging at one month after implantation illustrates expansion of the outer wall of the graft that partially resolves 5 months later. Conclusion In this patient, expansion of the lower extremity peripheral Bypass graft wall can be characterized in clinical scan times with a 3D-FSE MRI protocol using highly selective inner volume excitation followed by non-selective refocusing pulses. The resulting 3D images can potentially be used to study the biology of the vessel wall.
