多排CT灌注成像诊断急性脑缺血的实验研究

目的应用多排CT(MSCT)行脑CT灌注成像,研究多层面灌注参数图诊断兔大脑中动脉阻断(MCAO)模型上急性脑缺血病变的能力,并探讨其临床应用价值。方法将10只家兔分成缺血组和空白对照组,行脑MSCT灌注成像(CTPI)。缺血组分别在术后1、2、3h各行1次CTPI;对照组术后仅行1次CTPI。所有CTPI均为4层面成像。每层面CTPI均生成血流灌注图(perfusion)、峰值增强图(PEI)、峰值时间图(TTP)和平均通过时间图(MTT)。最后取兔脑沿CT扫描方向切片做2,3,5-三苯基氯化四氮唑(TTC)染色。测量缺血组术后1、2、3h各参数图及染色切片上所显示的缺血梗死区的容积百分比,用随机区组方差分析和线性相关分析进行统计处理。结果对照组2例在CTPI及染色切片上均显示阴性;缺血组8例中有6例成功显示出缺血梗死区。在4个层面上缺血灶至少累及2个层面。方差分析表明术后第1h与第2、3h间以及术后第1h时,MTT图与其它CTPI参数图间存在组间差异(P<0.001)。相关分析表明:第3hCTPI各参数图所测缺血区容积百分比与TTC染色结果均呈相关关系。其中以perfusion图和MTT图相关性最好(pearsonR=0.94和R=0.905),TTP图其次(R=0.864),而PEI图效果最差(R=0.814)。结论MSCT脑灌注成像能更为全面地显示脑缺血的范围和程度,具有良好的应用前景。

Experimental Study on Detection of Acute Cerebral Ischemia with Multislice CT Perfusion Imaging

Objective To investigate the ability of the four-slice perfusion maps derived by multislice CT(MSCT)perfusion imaging (CTPI) to detect ischemic lesion in rabbit models with the middle cerebral artery occlusion(MCAO). Methods Sequential dynamic CT studies were performed at four slices in 2 control rabbits and another 8 with MCAO. The volume of critically ischemic lesions on CTPI maps at 1st,2nd and 3rd hour after operation and the volume of infarction measured by postmortem 2,3,5- triphenyltetrazolium chloride (TTC) staining were analyzed by analysis of variance with random blocks design and linear correlation. Results In 6 of 8 animals of the ischemia group, critically ischemia or infarction was visible on perfusion maps and TTC-staining,while appearing negative in 2 control rabbits. In four-slice CTPI maps, lesions were visualized in 2 of 4 slices at least. The results of analysis of variance demonstrated that the intergroup differences were discovered between 1st , 2nd and 3rd hour after operation, and between MTT map and other CTPI maps (P<0.001). There was correlation between the lesion volume from CTPI maps and the infarction volume from TTC-staining. Perfusion map and MTT map had better correlation with TTC-staining (pearson R=0.94 and R=0.905) than TTP map(R=0.864) and PEI map(R=0.814).Conclusion MSCT perfusion imaging can better detect the size and degree of earlly cerebral ischemia,and can be beneficial to interprete ischemic penembra.