Abnormal fusion between the long P1 segment of the posterior cerebral artery and the long posterior communicating artery diagnosed by magnetic resonance angiography.

Abstract

Purpose: To describe a case of abnormal fusion between the long P1 segment of the posterior cerebral artery (PCA) and the long posterior communicating artery (PCoA) diagnosed by magnetic resonance angiography (MRA).

Methods: An 83-year-old woman with left pulsatile tinnitus underwent cranial 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 not 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. Thus, there was a large arterial ring. 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 was abnormal fusion between the long P1 segment of the PCA and the long PCoA.

Conclusion: We diagnosed the first case of abnormal fusion between the long P1 segment of the PCA and the long 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.