Impact of isolated fetal posterior cerebral artery variation on bilateral internal carotid artery diameter

Fetal posterior cerebral artery variation is defined as the condition in which the diameter of the posterior cerebral artery P1 segment is smaller than the posterior communicating artery. Various studies have demonstrated that Circle of Willis variations may lead to changes in the diameters and flow volumes of the arterial structures constituting the Circle of Willis. In our study, we aimed to investigate the impact of isolated fetal posterior cerebral artery variation on bilateral internal carotid artery diameters. In this retrospective study, with the approval of the ethics committee, 853 cases who underwent three dimensional time-of-flight magnetic resonance angiography in our hospital and met the inclusion criteria were included. The diameters of the internal carotid arteries and other intracerebral arteries were measured in all patients.All patients were evaluated for the presence of fetal posterior cerebral artery variation. In our study, the prevalence of fetal posterior cerebral artery variation was found to be %21,1. When comparing bilateral internal carotid artery diameters within the groups, a significant difference was observed in the isolated fetal posterior cerebral artery group, with the ICA diameter on the side of the variation being larger (p=0.005). When the mean internal carotid artery diameters were compared between the groups, the values in both the bilateral fetal posterior cerebral artery and isolated fetal posterior cerebral artery groups were significantly higher than those in the control group (p=0,032; p=0,001). Significant differences were also found in basilar artery diameters among the groups (p<0.001). The highest basilar artery diameter was observed in the control group, while the lowest was found in the bilateral fetal posterior cerebral artery group. Our study demonstrates that fetal posterior cerebral artery variation leads to significant diameter differences in the arteries constituting the Circle of Willis, particularly the internal carotid artery, and may result in potential intracranial hemodynamic alterations.