Koenig M, Kraus M, Theek C, Klotz E, Gehlen W, Heuser L
Departments of Radiology and Nuclear Medicine, Ruhr-University Bochum, Germany.
Stroke. 2001 Feb;32(2):431-7. doi: 10.1161/01.str.32.2.431.
Besides the delineation of hypoperfused brain tissue, the characterization of ischemia with respect to severity is of major clinical relevance, because the degree of hypoperfusion is the most critical factor in determining whether an ischemic lesion becomes an infarct or represents viable brain tissue. CT perfusion imaging yields a set of perfusion related parameters which might be useful to describe the hemodynamic status of the ischemic brain. Our objective was to determine whether measurements of the relative cerebral blood flow (rCBF), relative cerebral blood volume (rCBV), and relative time to peak (rTP) can be used to differentiate areas undergoing infarction from reversible ischemic tissue.
In 34 patients with acute hemispheric ischemic stroke <6 hours after onset, perfusion CT was used to calculate rCBF, rCBV, and rTP values from areas of ischemic cortical and subcortical gray matter. Results were obtained separately from areas of infarction and noninfarction, according to the findings on follow-up imaging studies. The efficiency of each parameter to predict tissue outcome was tested.
There was a significant difference between infarct and peri-infarct tissue for both rCBF and rCBV but not for rTP. Threshold values of 0.48 and 0.60 for rCBF and rCBV, respectively, were found to discriminate best between areas of infarction and noninfarction, with the efficiency of the rCBV being slightly superior to that of rCBF. The prediction of tissue outcome could not be increased by using a combination of various perfusion parameters.
The assessment of cerebral ischemia by means of perfusion parameters derived from perfusion CT provides valuable information to predict tissue outcome. Quantitative analyses of the severity of ischemic lesions should be implemented into the diagnostic management of stroke patients.
除了描绘灌注不足的脑组织外，对缺血严重程度的特征描述具有重要的临床意义，因为灌注不足的程度是决定缺血性病变会发展为梗死还是代表存活脑组织的最关键因素。CT灌注成像可得出一组与灌注相关的参数，这些参数可能有助于描述缺血性脑的血流动力学状态。我们的目的是确定相对脑血流量（rCBF）、相对脑血容量（rCBV）和相对达峰时间（rTP）的测量值是否可用于区分正在发生梗死的区域与可逆性缺血组织。
对34例发病后<6小时的急性半球缺血性卒中患者，采用灌注CT计算缺血皮质和皮质下灰质区域的rCBF、rCBV和rTP值。根据后续影像学研究结果，分别从梗死区和非梗死区获取结果。测试每个参数预测组织转归的效能。
rCBF和rCBV在梗死组织和梗死周边组织之间存在显著差异，但rTP无显著差异。rCBF和rCBV的阈值分别为0.48和0.60时，在区分梗死区和非梗死区方面表现最佳，rCBV的效能略优于rCBF。使用多种灌注参数组合并不能提高组织转归的预测能力。
通过灌注CT得出的灌注参数评估脑缺血可为预测组织转归提供有价值的信息。缺血性病变严重程度的定量分析应纳入卒中患者的诊断管理中。
