Double anastomoses between posterior cerebral artery and posterior communicating artery diagnosed by magnetic resonance angiography

Purpose To describe a case of double anastomoses between the posterior cerebral artery (PCA) and the posterior communicating artery (PCoA). Methods An 83-year-old woman with left pulsatile tinnitus underwent cranial magnetic resonance angiography (MRA) using a 3-Tesla scanner. MRA was performed using a standard 3-dimensional time-of-flight technique. Results MRA showed no dural arteriovenous fistula; however, there was a stenotic lesion in the precavernous segment of the left internal carotid artery (ICA). This lesion was considered to be the cause of her symptoms. In addition, the left PCA arose from the basilar artery and the left ICA. There was a small connecting artery between these two PCAs at their proximal segments. These two PCAs fused distally and formed a single PCA. Partial maximum intensity projection (MIP) images showed that the left anterior choroidal artery (AChA) appeared normal. Thus, we concluded that there was no hyperplastic AChA, and there were double anastomoses between the left PCA and PCoA. Conclusion We diagnosed the first case of double anastomosis between the PCA and the PCoA. Careful observation using MRA is important for the detection of rare arterial variations. Partial MIP MRA images are useful for identifying tiny arteries, such as the AChA.