The Experts below are selected from a list of 13044 Experts worldwide ranked by ideXlab platform
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, Christopher D Owens, Dimitrios Mitsouras, 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, Robert V Mulkern, Christopher D Owens, Hale Ersoy, Dimitrios Mitsouras, 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, Robert V Mulkern, Christopher D Owens, Hale Ersoy, Dimitrios Mitsouras, 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.
Michael S Conte - 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, Christopher D Owens, Dimitrios Mitsouras, 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, Robert V Mulkern, Christopher D Owens, Hale Ersoy, Dimitrios Mitsouras, 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.
Dimitris Mitsouras - 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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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, Christopher D Owens, Dimitrios Mitsouras, 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, Robert V Mulkern, Christopher D Owens, Hale Ersoy, Dimitrios Mitsouras, 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.