Usefulness of subtraction images in perfusion MR imaging of intracranial lesions

We performed perfusion imaging of 20 examinations in 18 patients with intracranial lesions. Forty-seven images were obtained by subtracting the fourth to the fiftieth image from the third image. The subtraction images showed increases or reductions in the blood flow, delay of cerebral circulation in 17 examinations of 15 cases, while the other three examinations were difficult to evaluate because of the small size of the lesions. We conclude that subtraction images can be a useful tool for the visual assessment of the blood flow in intracranial lesions. (author)