Albers G W
Department of Neurology and Neurological Sciences and the Stanford Stroke Center, Stanford University Medical Center, CA 94304, USA.
Neurology. 1998 Sep;51(3 Suppl 3):S47-9. doi: 10.1212/wnl.51.3_suppl_3.s47.
Diffusion-weighted imaging (DWI) is a new magnetic resonance imaging technique that detects the tiny random movements of water molecules (diffusion) in tissues. This technique allows a map of the average apparent diffusion coefficient (ADC) to be calculated. Shortly after the onset of an ischemic stroke, the ADC of brain tissue is significantly reduced because of cytotoxic edema. Over several days, the rapid initial drop in ADC is followed by a return to "pseudonormal" values at approximately 1 week. Subsequently, elevated ADC values are seen at chronic time points. DWI is remarkably sensitive in detecting and localizing acute ischemic brain lesions and allows differentiation of acute regions of ischemia from chronic infarcts. Recent studies have shown a high correlation between the volume of early DWI lesions and clinical neurologic outcome. In addition, the volume of the early DWI lesion correlates well with final infarct volume as measured by T2-weighted imaging. Therefore, this technique may facilitate optimal selection of patients for new medical therapies for stroke and may provide a highly sensitive technique for evaluating the efficacy of new treatments.
扩散加权成像（DWI）是一种新的磁共振成像技术，可检测组织中水分子的微小随机运动（扩散）。该技术能够计算出平均表观扩散系数（ADC）图。在缺血性卒中发作后不久，由于细胞毒性水肿，脑组织的ADC会显著降低。在数天内，ADC最初的快速下降之后，大约在1周时会恢复到“假性正常”值。随后，在慢性时间点会出现ADC值升高。DWI在检测和定位急性缺血性脑病变方面非常敏感，能够区分急性缺血区域和慢性梗死灶。最近的研究表明，早期DWI病变的体积与临床神经学预后之间存在高度相关性。此外，早期DWI病变的体积与通过T2加权成像测量的最终梗死体积密切相关。因此，该技术可能有助于为中风新药物治疗优化患者选择，并可能为评估新治疗方法的疗效提供一种高度敏感的技术。
