Assessment of ≥50% and <50% intracranial stenoses by transcranial color-coded duplex sonography

Abstract

Background and Purpose - A favorable risk-benefit ratio for warfarin compared with aspirin has been reported for the prevention of major vascular events in symptomatic ≥50% intracranial stenoses. Transcranial color-coded duplex sonography (TCCS) criteria providing an accurate detection of ≥50% and <50% stenoses of the anterior, middle, and posterior cerebral arteries and basilar and vertebral arteries were evaluated retrospectively with angiography used as the standard of reference. Methods - Prospectively collected TCCS, extracranial color-coded duplex sonography, and intra- arterial digital subtraction angiography data of 310 patients were reviewed. The patients had angiography for confirmation of symptomatic extracranial ≥70% carotid stenoses, symptomatic stenoses (peak systolic velocity higher than the corresponding mean value +2 SDs of 104 normal subjects), and occlusions of the middle cerebral or basilar artery previously assessed by ultrasound. The sonographer was not aware of angiographic findings. Results - TCCS would have detected all 31 of ≥50% intracranial stenoses with 1 false- positive and 35 of 38 <50% stenoses with 3 false-positives. One of 69 stenoses (1%) and 280 of 2741 normal arteries (10%) were missed because of inadequate insonation windows. The corresponding peak systolic velocity cutoffs for ≥50%/<50% stenoses were ≥155/≥120 cm/s (anterior cerebral artery), ≥220/≥155 cm/s (middle cerebral artery), ≥145/≥100 cm/s (posterior cerebral artery), ≥140/≥100 cm/s (basilar artery), and ≥120/≥90 cm/s (vertebral artery). Conclusions - TCCS may reliably assess ≥50% and <50% basal cerebral artery narrowing and prove useful for noninvasive management of patients with symptomatic intracranial stenoses.