MRI AND MR-ANGIOGRAPHY OF PERSISTENT TRIGEMINAL ARTERY

We describe the MRA and MR angiography (MRA) features of persistent tr igeminal artery (PTA) found incidentally in eight patients, with speci al attention to its origin, site and course. The different patterns of posterior communicating arteries were also noted. The PTA were shown on sagittal, coronal and axial MRI and on MRA. In four cases, the PTA arose from the lateral aspect of the intracavernous internal carotid a rtery, ran caudally, passing round the bottom of the dorsum sellae to join the basilar artery. In the other four cases, it arose from the me dial aspect, ran caudally through the sella turcica and pierced the do rsum sellae to join the basilar artery. The posterior communicating ar teries were present unilaterally in five cases and bilaterally in one, and absent bilaterally in two. Identification of a PTA with a trans-s ellar course is crucial if a trans-sphenoidal surgery is planned.