Matsumoto K, Lo E H, Pierce A R, Wei H, Garrido L, Kowall N W
Center for Imaging and Pharmaceutical Research, Harvard Medical School, Massachusetts General Hospital, Charlestown 02129, USA.
AJNR Am J Neuroradiol. 1995 May;16(5):1107-15.
To examine the mechanisms of further evolution that occurs from the early to late phase after initial changes in diffusion-weighted imaging after cerebral ischemia.
Sprague-Dawley rats were subjected to middle cerebral artery occlusion. Diffusion-, proton density-, T1- and T2-weighted imaging were performed on days 0, 2, and 6. Histologic examination (IgG, glial fibrillary acidic protein, and cresyl violet staining) was done after scanning.
Apparent diffusion coefficients (ADCs) in the ischemic hemisphere were significantly decreased on day 0. Thereafter, ADCs increased over time and became significantly higher than the contralateral side by day 6. Changes in basal ganglia occurred more rapidly than in cortex. Proton density-, T1-, and T2-weighted scans showed maximal changes on day 2. From day 0 to day 2, there are significant correlations between changes in ADC and changes in T1-weighted signals and T2-weighted signals. Histologic exam showed early neuronal injury on day 0, intense gliotic activity and protein leakage associated with infarction and edema on day 2, and cavitation in severely infarcted areas on day 6.
After initial reduction of ADC, the subsequent increase in ADC values on day 2 may be associated with vasogenic edema and cell lysis. Later elevations in ADC may be related to cavitation of infarcted tissue.
研究脑缺血后扩散加权成像初始变化后从早期到晚期进一步演变的机制。
对Sprague-Dawley大鼠进行大脑中动脉闭塞。在第0天、第2天和第6天进行扩散加权成像、质子密度加权成像、T1加权成像和T2加权成像。扫描后进行组织学检查（免疫球蛋白G、胶质纤维酸性蛋白和甲酚紫染色）。
缺血半球的表观扩散系数（ADC）在第0天显著降低。此后，ADC随时间增加，到第6天显著高于对侧。基底节的变化比皮质更快。质子密度加权成像、T1加权成像和T2加权成像在第2天显示出最大变化。从第0天到第2天，ADC变化与T1加权信号和T2加权信号变化之间存在显著相关性。组织学检查显示第0天有早期神经元损伤，第2天有与梗死和水肿相关的强烈胶质增生活动和蛋白渗漏，第6天严重梗死区域有空洞形成。
在ADC最初降低后，第2天ADC值随后的增加可能与血管源性水肿和细胞溶解有关。后期ADC升高可能与梗死组织的空洞形成有关。
