[Significance and pitfall of diffusion weighted image in super acute cerebral ischemia: investigation by...

We investigated the findings in diffusion weighted image (DWI) of super acute ischemia examined within 6 hours after onset by questionnaire study. The magnitude of magnetic field of MR machine, method of diffusion weighted imaging, the total number of cases, the number of cases with high signal intensity area on DWI and the number of decrease or disappearance of signal intensity were investigated. Answers were obtained from 16 institutes (64%). Totally, 232 cases of super acute ischemia examined within 6 hours after onset were imaged by DWI. High signal intensity area were detected in 189 cases (81.5%) of all, which disappeared or decreased in 10 cases (4.3%). Follow up DWI revealed a decrease in the area of high signal intensity in 5 (17.9%) of 28 cases who underwent thrombolysis by endovascular treatment. However, 6 (21.4%) or 28 cases resulted in hemorrhagic infarction. We must recognize the diffusion anisotropy, apparent diffusion coefficient, and b value in reading the DWI. In conclusion, high signal intensity area on DWI include not only irreversible infarction but also the reversible ischemia.