brain scan [AS, bragen + L, scandere, to climb] , a diagnostic procedure used to image the brain. Common modalities include CT, MRI, and PET. Imaging can be done with a radioisotope used to localize and identify intracranial masses, lesions, tumors, or infarcts. Intravenously injected radioisotopes accumulate in abnormal brain tissue and are traced and photographed by a scintillator or scanner. The nature and rate of accumulation of radioisotopes in pathological tissue are diagnostic of some lesions. Compare computed tomography. See also isotope, radioisotope.
