弥散磁共振成像观察实验性脑梗死ADC值的变化

Observation of the changes of ADC value of experimental cerebaral infarction with diffusion weighted magnetic imaging.

目的 用弥散磁共振成像观察实验性脑梗死灶水表面弥散系数 (apparentdiffusioncoefficient,ADC)值的变化。方法 用 60只SD大鼠行易卒中型肾血管性高血压 (RHRSP)模型 ,在术后 1 0周按Longa’s方法改良行左侧大脑中动脉闭塞 (MCAO)术。分别在闭塞 1 2h内的不同时间点及再灌注 48h后行T2加权成像 (T2WI)、磁共振弥散加权成像 (DWI) ,完成检查后将大鼠处死行TTC染色 ,比较在闭塞不同的时间点上在两次T2WI和DWI上病灶的演变和ADC值的改变。结果 缺血中心区的ADC值为 ( 0 45± 0 0 1 )× 1 0 - 5cm2 /s,半暗带为 ( 0 5 6± 0 0 2 )× 1 0 - 5cm2 /s,对侧平均值为 ( 0 66± 0 0 2 )× 1 0 - 5cm2 /s,相邻正常信号组织平均值为 ( 0 65± 0 0 3)× 1 0 - 5cm2 /s,经方差分析表明 ,前三者相互之间比较均有显著性差异 (P <0 0 0 1 ) ,而后两者之间比较无显著性差异 (P >0 0 5 ) ;再灌注 48h后 ,在 3h内复流各组梗死灶的平均ADC值为 ( 0 65± 0 0 2 )× 1 0 - 5cm2 /s ,与相邻正常信号组织相比无显著性差异 (P>0 0 5 )。而在 6h后复流各组的平均ADC值为 ( 0 70± 0 0 3)× 1 0 - 5cm2 /s,与相邻正常信号组织相比有显著性差异(P <0 0 5 )。结论 实验性MCAO 1 2h内缺血或梗死灶的ADC值降低 。

Objective To observe the changes in the apparent diffusion coefficient (ADC) of water in experimental cerebral infarction with diffusion weighted magnetic imaging. Methods Stroke prone two kidneys two clips renovascular hypertensive rat(SPRHR) model was established in 60 Sprague Dawley rats. Ten weeks after the operation, left middle cerebral artery occlusion (MCAO) was induced using the modified Longas' way. All the rats received magnetic resonance examination using T2 weighted imaging (T2WI) and diffusion weighted imaging (DWI) at different time points within 12 h of occlusion and 48 h post reperfusion, and after decapitation. TTC staining was performed on the rats brain slices. The evolution of the lesion size on twice T2WI and DWI and the changes of ADC value of penumbra were (0 56±0 02)×10 -5 cm 2/s, which was significantly lower than that of the contralateral side (0 66±0 02)×10 -5 cm 2/s, and the adjacent normal tissue was (0 65±0 03)×10 -5 cm 2/s. No significant difference in the ADC value between the later two groups ( P>0.05 ); After 48 h of reperfusion, the ADC value in the infarcted lesion was (0 65±0.02)×10 -5 cm 2/s when the occlusion was less than 3 h, similar to the ADC value in the adjacent normal tissue ( P >0 05);On the contrary, the ADC value in infarcted lesion was (0 70±0 03)×10 -5 cm 2/s when the occlusion was more than 3 h, significantly higher than that of the adjacent normal tissue ( P <0 05). Conclusions The ADC value in the ischemic or infracted lesions was lower within 12 h of experimental MCAO, but it turned to be normal or higher at 48 h after reperfusion.