Anastomosis between accessory middle cerebral artery and middle cerebral artery diagnosed by magnetic resonance angiography.

The accessory middle cerebral artery (MCA) is a common variation of the MCA that arises from the anterior cerebral artery. We report a patient with anastomosis of the accessory MCA with the main MCA, an extremely rare variant that we diagnosed by magnetic resonance (MR) angiography. Both partial maximum-intensity-projection and partial volume-rendering MR angiographic images obtained at 3 T are useful to identify such rare vascular variation.