Barnes D, McDonald W I, Landon D N, Johnson G
Institute of Neurology, National Hospital, Queen Square, London, UK.
Brain. 1988 Feb;111 ( Pt 1):83-94. doi: 10.1093/brain/111.1.83.
Quantitative nuclear magnetic resonance imaging techniques were used to study the development of astrocytic gliosis following a cortical freezing injury in 4 cats, and the findings compared with the histological and ultrastructural appearances of the affected white matter. In the first week after lesioning, the acutely oedematous white matter was apparent as a region of signal abnormality with very prolonged T1' and T2' relaxation times. Following resolution of this oedema, the images remained normal for a period of approximately three months. After this latent period they became abnormal once again, and the abnormal signal was most evident in images emphasizing differences between tissues in T1' and proton density, but not T2'. The light and electron microscopic appearances of the corresponding tissue were of astrocytic gliosis in each animal. Measurement of the relaxation times, T1' and T2', of the abnormal regions revealed an increase in T1' without a corresponding change in T2'. The T2' magnetization decay characteristics were consistently monoexponential, in contrast to the clearly biexponential T2 decay which has previously been demonstrated in the presence of acute vasogenic oedema. These findings suggest that the pattern of change of the relaxation times and T2 magnetization decay might provide a means of distinguishing between lesions in multiple sclerosis which are predominantly gliotic, and those containing significant amounts of oedema.
采用定量核磁共振成像技术研究了4只猫皮质冷冻损伤后星形胶质细胞增生的发展情况，并将研究结果与受影响白质的组织学和超微结构表现进行了比较。在损伤后的第一周，急性水肿的白质表现为信号异常区域，T1'和T2'弛豫时间非常延长。水肿消退后，图像在大约三个月的时间内保持正常。经过这段潜伏期后，图像再次变得异常，异常信号在强调组织间T1'和质子密度差异而非T2差异的图像中最为明显。每只动物相应组织的光镜和电镜表现均为星形胶质细胞增生。对异常区域的弛豫时间T1'和T2'进行测量，结果显示T1'增加，而T2'没有相应变化。与先前在急性血管源性水肿存在时所显示的明显双指数T2衰减相反，T2'磁化衰减特征始终为单指数。这些发现表明，弛豫时间和T2磁化衰减的变化模式可能为区分多发性硬化症中主要为胶质增生的病变和含有大量水肿的病变提供一种方法。
