A bilateral fetal origin of the posterior cerebral artery coexisting with an absent A1 segment of the anterior cerebral artery: A rare combination of variants with critical clinical consequences

Abstract The cerebral arterial circle variations are well-described due to their clinical significance for neurosurgeons and neuroradiologists. In this imaging report, we describe the unusual coexistence of three cerebral variants incidentally identified during magnetic resonance angiography (MRA) of a 44-year-old female patient. The right-sided first segment (A1) of the anterior cerebral artery (ACA) was absent, and the posterior cerebral arteries (PCAs) were bilaterally originating from the internal carotid arteries (a fetal-type origin). The coexistence of these variants is rare, and they significantly disrupt the patient’s primary collateral pathway. The clinical significance and consequences of such variants after stroke or transient ischemic attack cannot be overstated, underscoring the importance of the current imaging finding in understanding and managing these conditions.