Zhao F, Kuroiwa T, Miyasaka N, Nagaoka T, Nakane M, Tamura A, Mizusawa H
Department of Neurology and Neurological Science, Tokyo Medical and Dental University, Graduate School of Medical and Dental Sciences, Yushima 1-5-45, Bunkyo-ku, Tokyo 113-8510, Japan.
Brain Res. 2001 Mar 23;895(1-2):238-44. doi: 10.1016/s0006-8993(00)03281-9.
To correlate the magnetic resonance (MR) imaging characteristics of exofocal postischemic neuronal death (EPND) in the substantia nigra (SN) with associated histologic changes, we occluded the left middle cerebral artery of rats for 1, 4, 7, or 12 days. Day 1 (post-occlusion) T(2)-weighted images revealed high signal intensity indicative of infarction in the ipsilateral caudate nucleus, putamen, and cortex but not the SN. Diffusion-weighted images (DWIs) on day 1 similarly failed to reveal any changes in the SN. However, on day 4, DWIs revealed high signal intensity in the ipsilateral SN, in which the apparent diffusion coefficient (ADC) transiently decreased (P<0.05) while the T(2)-value increased (P<0.05). These measures returned to and remained at control levels on days 7 and 12. Histologic examination on day 4 revealed dark-staining neurons, markedly swollen perivascular astrocytic end-feet, many swollen neurons with cytoplasmic microvacuoles that mainly originated in the rough endoplasmic reticulum, and strongly roughed neuropils. Reactive astrocytes and dark neurons most frequently appeared on days 7 and 12. The severity of cellular swelling paralleled the change in the ADC. These results demonstrate that a transient high-intensity signal on DWIs, indicative of a decrease in the ADC, is predictive of EPND in the SN.
为了将黑质（SN）局灶性缺血后神经元死亡（EPND）的磁共振（MR）成像特征与相关的组织学变化相关联，我们将大鼠的左大脑中动脉闭塞1、4、7或12天。闭塞后第1天的T2加权图像显示同侧尾状核、壳核和皮质出现高信号强度，提示梗死，但黑质未出现。第1天的扩散加权成像（DWI）同样未显示黑质有任何变化。然而，在第4天，DWI显示同侧黑质出现高信号强度，其中表观扩散系数（ADC）短暂降低（P<0.05），而T2值升高（P<0.05）。这些指标在第7天和第12天恢复并维持在对照水平。第4天的组织学检查显示神经元染色加深、血管周围星形胶质细胞终足明显肿胀、许多神经元肿胀并伴有主要起源于粗面内质网的细胞质微泡，以及神经纤维网明显粗糙。反应性星形胶质细胞和深色神经元最常出现在第7天和第12天。细胞肿胀的严重程度与ADC的变化平行。这些结果表明，DWI上提示ADC降低的短暂高强度信号可预测黑质中的EPND。
