Echo-enhanced transcranial color-coded duplexsonography to study collateral blood flow in patients with symptomatic obstructions of the internal carotid artery and limited acoustic bone windows.

We prospectively evaluated 30 consecutive patients with echo-enhanced transcranial color-coded duplexsonography (TCCD) and correlative transfemoral digital subtraction angiography to assess the diagnostic efficacy of echo-enhanced TCCD for evaluation of collateral pathways through the circle of Willis in patients with limited acoustic bone windows and critical symptomatic carotid disease. Echo-enhanced TCCD detected collateral blood flow through the anterior communicating artery in 16 of 18 patients (sensitivity 89%, 95% CI 65-99%) and was false positive in one out of 12 patients without collateral flow (specificity 92%, 95% CI 59-100%). For the posterior communicating artery, sensitivity was 11/14 (79%, 95% CI 49-95%) and specificity was 15/16 (94%, 95% CI 70-100%). Echo-enhanced TCCD enables to study collateral blood flow through the communicating arteries of the circle of Willis with high sensitivity and specificity in patients with obstructions of the internal carotid artery and limited acoustic bone windows.