Persistent primitive olfactory artery: diagnosis with MR angiography.

We present a case of persistent primitive olfactory artery (PPOA) diagnosed with the aid of magnetic resonance (MR) angiography. The proximal right anterior cerebral artery (ACA) had an extremely long anteroinferomedial course along the ipsilateral olfactory tract, made a hairpin turn posterosuperiorly, and became a normal distal ACA. After reviewing the literature, we considered the proximal segment of this anomalous ACA to be a PPOA. To our knowledge, this is the first report of a patient with this anomalous ACA diagnosed with MR angiography.