Sparacia G, Iaia A, Assadi B, Lagalla R
DIBIMEL, Sezione di Scienze Radiologiche, Università di Palermo, Via A. Casella 7, I-90145 Palermo, Italy.
Radiol Med. 2007 Feb;112(1):113-22. doi: 10.1007/s11547-007-0125-9. Epub 2007 Feb 22.
The aim of this study was to assess the value of computed tomography (CT) perfusion parameters in differentiating tissue viability in acute stoke patients.
Thirteen patients (mean age 63.3 years) with nonhaemorrhagic stroke underwent multidetector perfusion CT within 3 h of symptom onset. Images were continuously acquired at the basal ganglia over 40 s during injection of 90 ml of iodinated contrast medium injected at a rate of 9 ml/s with a 9-s delay. Z-axis coverage was 20 mm. All patients underwent diffusion-weighted magnetic resonance imaging (DWI) within 12 h of perfusion CT to define the extent of the infarct. Perfusion CT data were analysed in regions of interests (ROIs) on regional cerebral blood volume (rCBV), regional cerebral blood flow (rCBF) and mean transit time (MTT) maps placed in various parts of the perfusion-deficient territory and in the contralateral hemisphere. Statistical analysis was performed using the analysis of variance (ANOVA) test to assess differences in CT perfusion parameters. Receiver operator characteristics (ROC) analysis was performed to assess possible threshold values that predict tissue infarction vs. viability.
Normal CT findings with abnormal CT perfusion parameters were seen in the region of infarction and in the viable tissue (penumbra) within a 1.5-cm distance from the infarct margin as outlined on DWI images. Infarcted areas demonstrated significant prolongation of MTT values compared with noninfarcted areas (p<0.0001). Average MTT was 9.8 s in areas of infarction, 5.1 s in the viable tissue adjacent to the infarct (penumbra), and 3.4 s in the contralateral control area. An MTT threshold level of 6.05 s has a 100% positive predictive value (sensitivity 84.6%, specificity 100%, accuracy 92.3%) for the presence of infarcted tissue. Average rCBF was 24.6 ml/100 g per min in infarcted tissue, 64.8 in penumbra and 70.8 in normal tissue. Average rCBV was 3.5 ml/100g in infarcted tissue, 3.9 in penumbra and 2.9 in normal tissue.
Prolongation of MTT was the most frequent CT perfusion finding observed in acute stroke patients. Average MTT values of 5.1 s may distinguish viable tissue, whereas MTT values >6.05 s identify infarcted tissue.
本研究旨在评估计算机断层扫描（CT）灌注参数在鉴别急性卒中患者组织存活能力方面的价值。
13例非出血性卒中患者（平均年龄63.3岁）在症状发作后3小时内接受了多排探测器灌注CT检查。在以9ml/s的速率注射90ml碘化造影剂并延迟9秒的过程中，于40秒内连续采集基底节区的图像。Z轴覆盖范围为20mm。所有患者在灌注CT检查后12小时内接受扩散加权磁共振成像（DWI），以确定梗死范围。在灌注缺损区域和对侧半球的不同部位放置感兴趣区（ROI），对灌注CT数据进行分析，测量局部脑血容量（rCBV）、局部脑血流量（rCBF）和平均通过时间（MTT）。采用方差分析（ANOVA）检验进行统计分析，以评估CT灌注参数的差异。采用受试者操作特征（ROC）分析来评估预测组织梗死与存活的可能阈值。
在DWI图像上勾勒出的梗死区域以及距梗死边缘1.5cm范围内的存活组织（半暗带）中，可见CT表现正常但CT灌注参数异常的情况。与非梗死区域相比，梗死区域的MTT值显著延长（p<0.0001）。梗死区域的平均MTT为9.8秒，梗死灶相邻的存活组织（半暗带）为5.1秒，对侧对照区域为3.4秒。MTT阈值水平为6.05秒时，对梗死组织存在的阳性预测值为100%（敏感性84.6%，特异性100%，准确性92.3%）。梗死组织的平均rCBF为24.6ml/100g每分钟，半暗带为64.8，正常组织为70.8。梗死组织的平均rCBV为3.5ml/100g，半暗带为3.9，正常组织为2.9。
MTT延长是急性卒中患者最常见的CT灌注表现。平均MTT值为5.1秒可能区分存活组织，而MTT值>6.05秒则提示梗死组织。
