Carvlin M J, Asato R, Hackney D B, Kassab E, Joseph P M
Department of Radiology, University of Pennsylvania, Philadelphia 19104-6086.
AJNR Am J Neuroradiol. 1989 Jan-Feb;10(1):13-7.
Human and rat cervical spinal cords were imaged with high-resolution spin-echo and inversion-recovery pulse sequences in an experimental 1.9-T MR system. The gross morphology of the cord was easily discernible in fresh and fixed specimens, including the white and gray commissures, dorsal and ventral horns, and lateral and posterior funiculi. The T1, T2, and spin-density values for gray and white matter were determined from these images and were found to be 914 msec, 114 msec, and 71% for white matter other than the dorsal columns, and 946 msec, 87 msec, and 80% for gray matter in human spinal cords. These values are reduced considerably after formalin fixation: T1 to 56% (white matter) and 54% (gray matter) of prefixation values, T2 to 52% (white matter) and 70% (gray matter) of fresh values, and spin density to 90% (white matter) and 96% (gray matter) of prefixation values. Interestingly, the central gray matter demonstrates higher signal intensity than the white matter on both short and long TR/TE images. This intensity difference was observed for both human and rat spinal cords, before and after fixation, and can be explained by the relatively small T1 differences between gray matter and white matter and the gray matter-white matter spin-density ratios: 1.127 for fresh and 1.203 for fixed specimens.
在一台实验性1.9-T磁共振成像（MR）系统中，使用高分辨率自旋回波和反转恢复脉冲序列对人和大鼠的颈脊髓进行成像。在新鲜和固定标本中，脊髓的大体形态清晰可见，包括白质和灰质连合、背角和腹角以及外侧和后索。从这些图像中确定了灰质和白质的T1、T2和自旋密度值，发现人脊髓中除背柱外的白质的T1、T2和自旋密度值分别为914毫秒、114毫秒和71%，灰质的相应值分别为946毫秒、87毫秒和80%。福尔马林固定后，这些值大幅降低：T1降至固定前值的56%（白质）和54%（灰质），T2降至新鲜值的52%（白质）和70%（灰质），自旋密度降至固定前值的90%（白质）和96%（灰质）。有趣的是，在短TR/TE和长TR/TE图像上，中央灰质的信号强度均高于白质。在人和大鼠脊髓中，无论固定前后均观察到这种强度差异，这可以通过灰质和白质之间相对较小的T1差异以及灰质与白质的自旋密度比来解释：新鲜标本为1.127，固定标本为1.203。
