Persistent Trigeminal Artery Variant: MR Angiographic Demonstration. A Report of Two Cases.

A variant (PTAV) is the persistence after birth of the fetal carotid-basilar anastomosis between the internal carotid artery and a cerebellar artery. We describe two cases of a PTAV demonstrated on MR angiography. A comparison with a persistant trigeminal artery is made and an explanation of the extended Saltzman classification is given. These variants have only little clinical significance, but their recognition is crucial before surgical or interventional procedures or to understand paradoxical cerebellar lesions. MRA appears inferior to selective angiography in diagnosing these variants.