A Study for Reversible Signal Intensity in Diffusion Weighted Image at Acute Stage of Cerebral Infarction

The high signal intensity (SI) of diffusion weighted image (DWI) is well correlated with complete brain infarction. High SI of DWI includes reversible and/or irreversible ischemia, and the borderline between them has not been confirmed clearly yet. In this report, we elucidate the clinical borderline of ischemic condition of reversibility concerned with SI of DWI at the acute ischemic stage. MRI data were collected in 15 patients with acute stroke who achieved recanalization within 6 hours from onset. SI was investigated with correlation to the apparent diffusion coefficient (ADC) and ratio to normal location as standard. An inversed correlation was demonstrated between signal intensity of DWI and ADC. The irreversible borderline was less than 0.56 (10-3 mm2/s) in ADC and it was equal to a signal intensity of more than 175 in DWI. The signal ratio effectively divided infarct and retained when the basic standard site was anatomical contralateral point. The irreversible borderline of the signal ratio was more than 1.4 to the contralateral portion in DWI. This study suggests SI in DWI can be a criterion for ischemic reversibility.