Mitsouras Dimitris, Owens Christopher D, Conte Michael S, Ersoy Hale, Creager Mark A, Rybicki Frank J, Mulkern Robert V
Department of Radiology, Applied Imaging Science Laboratory, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
Magn Reson Med. 2009 Sep;62(3):607-15. doi: 10.1002/mrm.22037.
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.
在1.5特斯拉场强下，采用高分辨率黑血三维（3D）体内心脏（IV）快速自旋回波（FSE）MRI成像的下肢外周静脉搭桥移植物（LE-PVBG）在T1加权图像上呈现双层外观，而在相应的T2加权图像上仅内层可见。本研究对6例植入后6个月成像的患者的这种差异进行了量化，并将这种差异归因于在两个具有组织学相关性的标本中离体测量的血管壁组织的T(2)弛豫率。对体内成像的两个LE-PVBG血管壁成分的视觉观察得到证实具有显著性（P < 0.0001），不同对比之间的平均血管壁面积差异为6.8 +/- 2.7平方毫米，T1加权与T2加权血管壁面积之比为1.67 +/- 0.28。这种差异归因于外膜的T(2)弛豫显著缩短（P < 0.0001）（T(2) = 52.6 +/- 3.5毫秒），与新生内膜/中膜相比（T(2) = 174.7 +/- 12.1毫秒）。值得注意的是，外膜组织表现出双指数T(2)信号衰减（与单指数相比，P < 0.0001）。我们的结果表明，高分辨率黑血3D IV-FSE通过能够独立可视化新生内膜/中膜和外膜的相对重塑，可用于体内研究搭桥移植物壁成熟的生物学和病理生理学。
