TRANSCRANIAL COLOR-CODED DUPLEX SONOGRAPHY IN THE EVALUATION OF COLLATERAL FLOW-THROUGH THE CIRCLE OF WILLIS

PURPOSE: To determine the sensitivity, specificity, and positive and n egative predictive values of transcranial color-coded duplex sonograph ic (TCCD) evaluation of cross flow through the anterior (ACoA) and pos terior (PCoA) communicating arteries in patients with occlusive cerebr ovascular disease, METHODS: We studied prospectively 132 patients (37 women, 95 men; mean age, 60 years) with stenoses of more than 69% redu ction in vessel diameter (n=93) and occlusions (n=52) of the internal carotid artery, and three occlusions of the basilar artery. The sonogr apher was aware of extracranial sonographic findings but was blinded t o the results of cerebral angiography. RESULTS: Nine patients (7%) wit h thick bones preventing transtemporal insonation and three patients ( 3%) with occlusions of the middle (n=3) and anterior (n=1) cerebral ar teries were excluded. Sensitivity of TCCD for detection of collateral flow through the ACoA in patients with occlusive carotid artery diseas e was 98%, specificity was 100%, positive predictive value was 100%, a nd negative predictive value was 98%. The corresponding Values for the PCoA were 84%, 94%, 94%, and 84%, respectively. All three functional PCoAs were identified in patients with occluded basilar arteries. CONC LUSION: TCCD is a valuable method for noninvasive evaluation of cross flow through the ACoA in patients with adequate sonographic windows. H owever, TCCD evaluation of cross flow through the PCoA is less reliabl e, because hemodynamic criteria may cause falsely positive and falsely negative results.