Department of Clinical Neurosciences, The Stroke Research Group, University of Cambridge, Cambridge, UK.
J Cereb Blood Flow Metab. 2011 Apr;31(4):1027-35. doi: 10.1038/jcbfm.2010.197. Epub 2010 Nov 3.
Depicting the salvageable tissue is increasingly used in the clinical setting following stroke. As absolute cerebral blood flow (CBF) is difficult to measure using perfusion magnetic resonance or computed tomography and has limitations as a penumbral marker, time-based variables, particularly the mean transit time (MTT), are routinely used as surrogates. However, a direct validation of MTT as a predictor of the penumbra threshold using gold-standard positron emission tomography (PET) is lacking. Using (15)O-PET data sets obtained from two independent acute stroke samples (N=7 and N=30, respectively), we derived areas under the curve (AUCs), optimal thresholds (OTs), and 90%-specificity thresholds (90%-Ts) from receiver operating characteristic curves for absolute MTT, MTT delay, and MTT ratio to predict three penumbra thresholds ('classic': CBF <20 mL/100 g per min; 'normalized': CBF ratio <0.5; and 'stringent': both CBF <20 mL/100 g per min and oxygen extraction fraction >0.55). In sample 1, AUCs ranged from 0.79 to 0.92, indicating good validity; OTs ranged from 7.8 to 8.3 seconds, 2.8 to 4.7 seconds, and 151% to 267% for absolute MTT, MTT delay, and MTT ratio, respectively, while as expected, 90%-Ts were longer. There was no significant difference between sample 1 and sample 2 for any of the above measurements, save for a single MTT parameter with a single penumbra threshold. These consistent findings from gold-standard PET obtained in two independent cohorts document that MTT is a very good surrogate to CBF for depicting the penumbra threshold.
在中风后，描绘可挽救组织的方法在临床中越来越多地被使用。由于绝对脑血流 (CBF) 很难使用灌注磁共振或计算机断层扫描进行测量，并且作为半影标记具有局限性，因此基于时间的变量，特别是平均通过时间 (MTT)，通常被用作替代指标。然而，直接使用金标准正电子发射断层扫描 (PET) 验证 MTT 作为半影阈值的预测指标尚缺乏。我们使用从两个独立的急性中风样本中获得的 (15)O-PET 数据集（分别为 N=7 和 N=30），从受试者工作特征曲线中为绝对 MTT、MTT 延迟和 MTT 比得出曲线下面积 (AUCs)、最佳阈值 (OTs) 和 90%特异性阈值 (90%-Ts)，以预测三个半影阈值（“经典”：CBF <20 mL/100 g 每分钟；“归一化”：CBF 比 <0.5；和“严格”：CBF <20 mL/100 g 每分钟和氧提取分数 >0.55）。在样本 1 中，AUC 范围为 0.79 至 0.92，表明具有良好的有效性；OTs 范围分别为 7.8 至 8.3 秒、2.8 至 4.7 秒和 151%至 267%，用于绝对 MTT、MTT 延迟和 MTT 比，而 90%-Ts 更长。除了一个具有单个半影阈值的单个 MTT 参数外，样本 1 和样本 2 之间在任何上述测量中均无显著差异。这些来自两个独立队列的金标准 PET 的一致发现证明，MTT 是描绘半影阈值的 CBF 的非常好的替代指标。
