磁共振弥散/灌注加权成像确认局灶脑缺血半暗带的实验研究  

Experimental studies on the identification of focal brain ischemic penumbra with diffusion/perfusion weighted magnetic imaging

作　　者：肖小华[1] 黄如训[1] 吕衍春 李玲[1] 梁康福[3] 殷梅[4] 罗柏宁[3] 苏镇培[1] 孟悛非[3] 

机构地区：[1]中山医科大学附属第一医院神经科,510080 [2]中山医科大学附属肿瘤医院影像介入科 [3]中山医科大学附属第一医院放射科,510080 [4]昆明医学院附属二院神经科

出　　处：《中国神经精神疾病杂志》2000年第3期148-151,共4页Chinese Journal of Nervous and Mental Diseases

摘　　要：目的　探讨超急性期确认局灶脑缺血半暗带的范围和演变规律。方法　用易卒中型肾血管性高血压大鼠(RHRSP)行左侧腔内线栓MCAO术 ,分别在闭塞 12h内的不同时间点及再灌注 48h后行T2 加权成像 (T2 WI)、磁共振弥散加权成像 (DWI)和磁共振灌注加权成像 (PWI)。将大鼠处死后行TTC染色 ,比较在闭塞不同的时间点上在两次T2 WI和DWI上病灶的演变和TTC染色上梗死灶的改变。结果　DWI在闭塞 30min时显示出确切的病灶 ,而T2 WI要在 3h以后才能显示出病灶 ;自 30min至 6h ,DWI所显示的病灶持续扩大 ,可逆性部分占首次DWI上病灶的百分比 (%RP)逐渐缩小 ,最终为负数 ;PWI在MCAO闭塞的即刻即在时间 信号强度曲线上表现为最大下降幅度的减小 ,复通后上升 5 0 %以上 ;半暗带部分水的表面弥散系数值 (ADC)为 (0 5 6± 0 0 2 )× 10 -5cm2 /s。结论　DWI能在超急性期 (3h以内 )显示出缺血病灶 ,根据梗死中心和梗死周边的ADC值的不同可以分辨出可逆性和不可逆性损伤的缺血组织 ;本模型的缺血半暗带存在的时间为6h。Objective Explore the way of identifying the size and evolving process of ischemic penumbra of focal cerebral ischemia. Methods Left middle cerebral artery occlusion (MCAO) model were reproduced according to Longas method with modification using stroke prone type of two kidneys two clips renovascular hypertensive rats. The rats received magnetic resonance examination of T 2 weighted imaging (T 2WI), diffusion weighted imaging (DWI) and perfusion weighted imaging (PWI) at different times within 12 h of occlusion and 48 h post reperfusion, and after decapitation TTC staining were performed on the rats brain slices. The evolution of the lesion size on twice T 2WI and DWI and the changes of TTC infarcted size were compared. Results DWI could identify definite lesion within 30 min of occlusion, and T 2WI could not show it until 3 h later; from 30 min to 6 h, the lesion size on DWI expanded with continuation, and the percentage of reversible portion (%RP) decreased gradually (P<0.001) till %RP became a negative number; PWI showed the occlusion with be decreasing of maximum reducing amplitude of time signal intensity, and it increased more than 50% when perfusion were resumed; the value of apparent diffusion coefficient of water (ADC) of penumbra were (0.56±0.02)×10 -5 cm2/s. Conclusions DWI can identify ischemic lesion at hyper acute stage of stroke, and differentiates reversible from irreversible ischemic injury; the duration of ischemic penumbra of this model is 6 houres.

关 键 词：磁共振成像 局灶脑缺血 PWI DWI 缺血半暗带 

分 类 号：R743.31[医药卫生—神经病学与精神病学]