Effectiveness of contrast regimens in CT detection of vascular malformations of the brain.

Forty-three patients with cerebral vascular malformation were studied with precontrast, immediate contrast, and 1 hr delayed high dose contrast computed tomography (CT) scans. The precontrast scans were abnormal in 81% of patients. The delayed high dose scans demonstrated one angiographically occult, thrombosed arteriovenous malformation not seen on pre- or immediate contrast scans, four cases with additional zones of encapsulated hemorrhage or infarction not seen on pre- or immediate contrast CT, and two cases of venous angiomas seen on immediate contrast scans but not on delayed high dose scans. In 50% of patients, large vessels surrounding the malformation faded on the delayed dose scans which were less specific for vascular malformation than immediate contrast CT. We conclude that: (1) delayed high dose scans offer no significant advantage in patients with symptoms suggesting vascular malformation of the brain; and (2) while less specific than immediate contrast CT, these scans do not preclude detection of vascular malformations of the brain. Therefore, delayed high dose CT can be used in patients with suspected blood-brain barrier lesions without fear of missing vascular malformations.