von Kummer Rüdiger, Dzialowski Imanuel
Institut für Diagnostische und Interventionelle Neuroradiologie, Universitätsklinikum Carl Gustav Carus, Fetscherstr. 74, 01307, Dresden, Germany.
Elblandklinikum Meißen, Neurologische Rehabilitationsklinik Großenhain, Nassauweg 7, 01662, Meißen, Germany.
Neuroradiology. 2017 Jun;59(6):545-553. doi: 10.1007/s00234-017-1847-6. Epub 2017 May 24.
In acute cerebral ischemia, the assessment of irreversible injury is crucial for treatment decisions and the patient's prognosis. There is still uncertainty how imaging can safely differentiate reversible from irreversible ischemic brain tissue in the acute phase of stroke.
We have searched PubMed and Google Scholar for experimental and clinical papers describing the pathology and pathophysiology of cerebral ischemia under controlled conditions.
Within the first 6 h of stroke onset, ischemic cell injury is subtle and hard to recognize under the microscope. Functional impairment is obvious, but can be induced by ischemic blood flow allowing recovery with flow restoration. The critical cerebral blood flow (CBF) threshold for irreversible injury is ~15 ml/100 g × min. Below this threshold, ischemic brain tissue takes up water in case of any residual capillary flow (ionic edema). Because tissue water content is linearly related to X-ray attenuation, computed tomography (CT) can detect and measure ionic edema and, thus, determine ischemic brain infarction. In contrast, diffusion-weighted magnetic resonance imaging (DWI) detects cytotoxic edema that develops at higher thresholds of ischemic CBF and is thus highly sensitive for milder levels of brain ischemia, but not specific for irreversible brain tissue injury.
CT and MRI are complimentary in the detection of ischemic stroke pathology and are valuable for treatment decisions.
在急性脑缺血中，评估不可逆损伤对于治疗决策和患者预后至关重要。在中风急性期，影像学如何安全地区分可逆性与不可逆性缺血脑组织仍存在不确定性。
我们在PubMed和谷歌学术上搜索了描述在可控条件下脑缺血病理和病理生理学的实验和临床论文。
在中风发作后的最初6小时内，缺血性细胞损伤很细微，在显微镜下难以识别。功能障碍很明显，但可由缺血性血流诱导产生，血流恢复后可恢复。不可逆损伤的临界脑血流量（CBF）阈值约为15毫升/100克×分钟。低于此阈值时，若存在任何残余毛细血管血流（离子性水肿），缺血脑组织会吸收水分。由于组织含水量与X射线衰减呈线性相关，计算机断层扫描（CT）可以检测和测量离子性水肿，从而确定缺血性脑梗死。相比之下，扩散加权磁共振成像（DWI）检测到的细胞毒性水肿在缺血性CBF阈值较高时出现，因此对较轻程度的脑缺血高度敏感，但对不可逆脑组织损伤不具有特异性。
CT和MRI在检测缺血性中风病理方面具有互补性，对治疗决策很有价值。
