Centre for Clinical Brain Sciences, University of Edinburgh, United Kingdom (A. Alzahrani).
Department of Diagnostic Radiology, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia (A. Alzahrani).
Stroke. 2023 Feb;54(2):558-566. doi: 10.1161/STROKEAHA.122.041241. Epub 2023 Jan 5.
Treatment for ischemic stroke can be offered beyond conventional time limits for patients with favorable computed tomography perfusion (CTP), but this is not universally available. We sought a threshold for brain attenuation on nonenhanced computed tomography (NECT) to differentiate CTP-defined penumbra vs core, and correlated NECT features with CTP.
We retrospectively assessed consecutive patients presenting to King Abdulaziz University Hospital with ischemic stroke (2017-2020), baseline NECT, and a visible defect on concurrent CTP. Using CTP as the reference standard, we measured the attenuation of ischemic and healthy contralateral brain on NECT to produce attenuation ratios (ischemic/normal) for penumbra and core. We used area under the receiver operating characteristic curve to estimate the optimal computed tomography (CT) attenuation ratio for penumbra. Per patient, we qualitatively assessed 8 regions within the affected cerebral hemisphere: on NECT as normal, hypoattenuating (with/out swelling), or isolated swelling and on CTP as normal, penumbra, or core. We sought associations between isolated swelling and penumbra, and between hypoattenuation and core.
We include 142 patients (86 male), mean age 61±14 years. Median 261 minutes (interquartile range, 173-382) to NECT. We measured 206 ischemic lesions (124 penumbra, 82 core). Optimal CT attenuation ratio for identifying penumbra was >0.87, with 86% sensitivity 91% specificity (area under the receiver operating characteristic curve, 0.95 [95% CI, 0.92-0.98]; <0.0001). We qualitatively assessed 976 cerebral regions (72 isolated swelling, 254 hypoattenuation). On NECT, isolated swelling usually corresponded to CTP penumbra (70/72, 97%), whereas visible NECT hypoattenuation was found with core (141/254, 56%) and penumbra (109/254, 43%). CTP core lesions were rarely normal on NECT (13/155, 8%).
After ischemic stroke, brain tissue viability can be assessed using NECT. Isolated swelling is highly specific to penumbra. Visible hypoattenuation does not always represent core, nearly half of such lesions were penumbral on concurrent CTP and can be differentiated by measuring lesion attenuation.
对于 CT 灌注（CTP）显示有良好表现的缺血性脑卒中患者，可以提供超过常规时间限制的治疗，但这种治疗并非普遍可用。我们寻求一种基于非增强 CT（NECT）的脑衰减阈值来区分 CTP 定义的缺血半暗带和核心区，并将 NECT 特征与 CTP 相关联。
我们回顾性评估了 2017 年至 2020 年期间在阿卜杜勒阿齐兹国王大学医院就诊的连续缺血性脑卒中患者的基线 NECT 和同时进行的 CTP 可见缺损。使用 CTP 作为参考标准，我们测量了 NECT 上缺血和健康对侧大脑的衰减，以产生缺血半暗带和核心区的衰减比（缺血/正常）。我们使用接收者操作特征曲线下的面积来估计缺血半暗带的最佳 CT 衰减比。对每个患者，我们在受累大脑半球的 8 个区域内进行定性评估：NECT 上正常、低衰减（伴/不伴肿胀）或孤立性肿胀，而 CTP 上正常、缺血半暗带或核心区。我们探讨了孤立性肿胀与缺血半暗带之间的关系，以及低衰减与核心区之间的关系。
我们纳入了 142 名患者（86 名男性），平均年龄 61±14 岁。NECT 中位数时间为 261 分钟（四分位距，173-382）。我们测量了 206 个缺血性病变（124 个缺血半暗带，82 个核心区）。识别缺血半暗带的最佳 CT 衰减比为>0.87，敏感性为 86%，特异性为 91%（接收者操作特征曲线下的面积，0.95[95%CI，0.92-0.98]；<0.0001）。我们对 976 个脑区进行了定性评估（72 个孤立性肿胀，254 个低衰减）。NECT 上，孤立性肿胀通常与 CTP 缺血半暗带相对应（70/72，97%），而可见的 NECT 低衰减与核心区（141/254，56%）和缺血半暗带（109/254，43%）有关。NECT 上很少能看到核心区病变正常（13/155，8%）。
缺血性脑卒中后，可以使用 NECT 评估脑组织的存活能力。孤立性肿胀高度提示缺血半暗带。可见的低衰减并不总是代表核心区，其中近一半的病变在同时进行的 CTP 上是缺血半暗带，可以通过测量病变衰减来区分。
