Diagnosis of acute ischemic stroke based on time-to-peak and diffusion-weighted magnetic resonance imaging.

Rapid and accurate diagnosis of the hemodynamics of the brain is essential for the treatment of acute ischemic stroke. This study investigated whether time-to-peak and diffusion-weighted magnetic resonance (MR) imaging are useful for predicting the course of stroke. Fourteen patients with non-lacunar acute ischemic stroke underwent emergent MR imaging within 24 hours from the onset followed by cerebral angiography and xenon-enhanced computed tomography (CT). Serial CT was obtained to monitor changes in the size and nature of the infarct. Volumes of the abnormal lesions demonstrated on time-to-peak (VT) or diffusion-weighted (VD) images were measured, and the ratio of VT to VD was calculated. Based on this ratio, patients were classified into three groups: Group 1 (VT/VD 0.5-1.5, n = 9), Group 2 (VT/VD > 1.5, n = 3), and Group 3 (VT/VD < 0.5, n = 2). The size of the infarct detected as a low-density area on serial CT scans did not change significantly throughout the course in Group 1 patients, but showed enlargement in all three patients in Group 2. Two patients in Group 3 had major trunk occlusion followed by spontaneous reperfusion, and both developed hemorrhagic transformation. Our study showed that classification of ischemic stroke based on the VT/VD ratio was predictive of the time course of the infarct, and may be useful in selecting the initial therapeutic procedure immediately after the onset of stroke.