ASSESSMENT OF THE POSTERIOR COMMUNICATING ARTERY BY TRANSCRANIAL COLOR-CODED DUPLEX SONOGRAPHY

Background and Purpose The aim of this study was to investigate flow v elocity and flow direction in the posterior communicating artery (Pcom A) by means of transcranial color-coded duplex sonography (TCCD) and t o compare the results with angiographic findings. Methods Thirty patie nts with unilateral occlusion of the internal carotid artery (TCA) due to atherosclerosis (n=15) or balloon occlusion (n=15) and 50 normal s ubjects were included. The circle of Willis was insonated through the temporal bone window. In 24 patients with unilateral TCA occlusion, an giograms were available and were compared with the results of TCCD. Re sults The PcomA could be detected unilaterally in 70% of normal subjec ts and bilaterally in 30%. A retrograde flow direction in the PcomA fr om the posterior cerebral artery to the lCA was found in 75% of the no rmal control subjects. The mean peak flow velocity in normal PcomAs wa s 36+/-15 cm/s (+/-SD). No significant differences in flow velocity we re found between unilaterally and bilaterally detectable PcomAs or bet ween retrograde and orthograde PcomAs. In patients with unilateral ICA occlusion we observed ipsilaterally a retrograde flow direction, with an elevation of flow velocity (64+/-10 cm/s) compared with the contra lateral side (27+/-14 cm/s; P<.001). Conclusions TCCD appears to be a valuable method to determine flow velocity and how direction not only in the large intracranial vessels but also in the smaller communicatin g arteries. In the future this method could be useful for the planning of ICA balloon occlusions and in deciding whether to perform extracra nial/intracranial bypass surgery. It could furthermore show intracrani al collaterals in patients with cerebrovascular disease and help to es timate the risk of watershed infarctions in patients with asymptomatic high-grade ICA stenosis and in patients undergoing carotid endarterec tomy.