扩散和灌注加权成像对兔脑缺血半暗带的量化

Diffusion and perfusion weighted imaging in quantization of ischemic penumbra in brain of rabbits

目的:探讨磁共振扩散加权成像(DWI)和灌注加权成像(PWI)在对被挽救缺血半暗带(IP)评价中的价值。方法:将制作成功的58只兔大脑中动脉闭塞(MCAO)模型随机分为永久缺血组(A组)和缺血再灌注组(B组);A组再按缺血1、3、6、12、24、48 h分组(A_1～6组),B组再按缺血1h后再灌注0、2、5、11、23、47h分组(B_(1～6)组)。然后,对各组行I)WI和PWI检查。结果:缺血再灌注组DWI像上异常信号区面积明显小于永久缺血组;缺血24h,梗死范围基本稳定。缺血1h,当表观扩散系数(ADC)比值、相对脑血容量(rCBV)比值和相对平均通过时间(rMTT)比值分别为(73.40±4.33)%、(46.83±9.89)%、1.58±0.04时,该区可能为IP;当ADC比值和rCBV比值分别低于(58.83±6.06)%和(22.87±8.19)%、rMTT比值大于1.94±0.1时,缺血脑组织将会发生不可逆性坏死。结论:DWI结合PWI能够快速、有效地评价IP。

Objective： To discuss the value of diffusion weighted imaging （DWI） and perfusion weighted imaging （PWI） in the evaluation of ischemic penumbra （IP） salvaged. Methods： Fifty-eight successful models of middle cerebral artery occlusion （MCAO） with rabbits were randomly divided into permanent ischemic group （A group） and ischemic reperfusion group （B group）. The A group was further divided into ischemic 1h, 3h, 6h, 12h, 24h, 48h groups （A1-6 group）. The B group was further divided into reperfusion Oh, 2h, 5h, 11h, 23h, 47h groups （B1-4 group ） after ischemic lh. Then every group was examined with modalities including DWI and PWI. Results： The area of the abnormal signal intensity on DWI in ischemic reperfusion group was significantly smaller than that in permanent ischemic group at the same time; at ischemic 24h, the area of infarction got smoothly. At ischemic lh, if the ADC, rCBV, rMTT ratio of region of interest changed respectively during（73.40± 4.33）% ,（46.83±9.89）% and 1. 58±0.04, it might be IP, but if the ADC, rCBV ratio of region of interest changed below respectively（58.83±6.06）%,（22.87±8.19）%, and the rMTT ratio of region of interest was higher than 1.94±0.11, it would become inreverdible necrosis. Conclusion： Combined DWI with PWI could evaluate IP quickly and efficiently.