By studying patients with clinically suspected cerebrovascular occlusive disease using dynamic CT technique, we have shown that contrast peak attenuation of the whole normal cerebral tissue was uniformly reached at the same time within a given individual. On the other hand, the delay of peak time was shown to correlate with some vascular occlusive mechanism. The main implications of delayed contrast peak time can be summarized as follows: Reduced regional blood flow due to stenosis or occlusion of main vessel without tissue damage. Delayed contrast arrival time due to occlusion of main vessel, but with sufficient circulation. Tissue organically injured by cerebrovascular occlusion.