Early detection of cerebral ischemic lesion using diffusion-weighted MRI.

We performed serial diffusion-weighted imaging (DWI) in a patient with right middle cerebral arterial occlusion using 1.0 T MRI. The initial DWI demonstrated suppression of water diffusion in the gray matter in the ischemic lesion as a high signal area 4 h after stroke onset, when T2-weighted imaging failed to detect any parenchymal injury. Repeat DWI 9 h after onset demonstrated the whole infarct, whereas it was not demonstrated by T2-weighted imaging until 48 h. Furthermore, the regional apparent diffusion coefficient (ADC) had already decreased significantly in both the gray and white matters of the ischemic lesion 4 h after onset, even though hyperintensity was not visible in the white matter on the DWI. The features in this case indicate that DWI in conjunction with the assessment of regional ADC can provide important information regarding the evolving infarct at a very early stage even when a relatively low tesla clinically available MRI unit is used.