Color velocity imaging quantification in the detection of intracranial collateral flow

Background and Purpose-The development of intracranial collateral circulation is associated with a lower risk of stroke. A noninvasive technique that can reliably detect the presence of intracranial collaterals would be a valuable factor in the assessment of risk in patients with occlusive cerebrovascular disease. Methods-Color velocity imaging quantification was used to measure the blood flow volume of the common carotid and vertebral arteries in 40 patients with carotid occlusive disease. The blood flow volumes in these arteries were correlated with angiographic evidence of collaterals to establish the best cutoffs for detecting intracranial collateral circulation. Results-A blood flow volume of either greater than or equal to370 mL/min in the common carotid artery or greater than or equal to120 mL/min in the vertebral artery was indicative of the presence of intracranial collaterals. The sensitivity and specificity for the common carotid artery were 92.3% [95% confidence interval (0), 62.1 to 99.6] and 92.1% (95% Cl, 77.5 to 97.9), respectively. The sensitivity and specificity for the vertebral artery were 75.0% (95% Cl, 35.6 to 95.5) and 87.5% (95% Cl, 66.5 to 96.7), respectively. Conclusions-Color velocity imaging quantification offers a noninvasive, accurate method for detecting the presence of intracranial collateral circulation and quantifying its magnitude. This technique would be a useful adjunct in screening or continuous monitoring of patients with severe carotid occlusive disease.