Magnetic Resonance Unit, Medica Sur Hospital & Clinic Foundation, Mexico City, Mexico.
Clin Radiol. 2012 Mar;67(3):250-7. doi: 10.1016/j.crad.2011.08.020. Epub 2011 Oct 21.
To determine the accuracy of the perfusion/diffusion-weighted imaging (PWI/DWI) parameters [time to peak (TTP), mean time to peak (MTT), relative cerebral blood volume (rCBV), and relative cerebral blood flow (rCBF) maps]; in the evaluation of acute versus hyperacute ischaemic stroke.
Fifty-five patients with symptomatic hyperacute (first 6h) or acute (7-24h) ischaemic stroke underwent diffusion and perfusion evaluation. Statistical analysis included Student's t-test, receiver operating characteristics (ROC) analysis of apparent diffusion coefficient (ADC), TTP, MTT, CBV, and CBF; correlation, linear, and logistic regression analysis.
Area under receiver operating characteristics (AUROC) analysis identified the ADC cut-off value 385×10(-6)mm(2)/s, MTT at 109.5%, TTP at 3.05s, CBV at 129%, and CBF at 98.5% (the record of the time of onset was considered the reference standard). The best performance corresponded to TTP, which showed a sensitivity of 0.94 and specificity of 0.88 (p<0.001).
Based on the present findings, hyperacute penumbra is reliably defined with a TTP >3s with no visible changes in diffusion. ADC, rCBF, and rCBV are not useful for discriminating between acute and hyperacute ischaemic stroke.
确定灌注/弥散加权成像（PWI/DWI）参数[达峰时间（TTP）、平均达峰时间（MTT）、相对脑血容量（rCBV）和相对脑血流量（rCBF）图]在评估急性与超急性缺血性卒中中的准确性。
55 例症状性超急性（发病 6 小时内）或急性（7-24 小时）缺血性卒中患者接受弥散和灌注评估。统计分析包括学生 t 检验、表观弥散系数（ADC）、TTP、MTT、CBV 和 CBF 的受试者工作特征（ROC）分析；相关性、线性和逻辑回归分析。
ROC 分析的曲线下面积（AUROC）确定 ADC 截断值为 385×10(-6)mm(2)/s，MTT 为 109.5%，TTP 为 3.05s，CBV 为 129%，CBF 为 98.5%（记录发病时间为参考标准）。最佳表现对应于 TTP，其灵敏度为 0.94，特异性为 0.88（p<0.001）。
基于目前的发现，TTP >3s 且弥散未见明显变化时，可靠地定义超急性半暗带。ADC、rCBF 和 rCBV 对于区分急性和超急性缺血性卒中没有帮助。
