Diagnostic value of transcranial Doppler ultrasound for stenosis of extracranial internal carotid artery

Objective To evaluate the validity of transcranial Doppler (TCD) in diagnosing stenosis or occlusion of extracranial internal carotid artery (ICA) and to find out the reference values to estimate the degree of carotid stenosis with TCD study. Methods (1) cases with ischemic cerebrovascular diseases were examined by TCD. Based on studies of extracranial and intracranial hemodynamics .patients suffered from unilateral or bilateral extracranial ICA diseases were screened out. (2) cases with extracranial ICA diseases were examined by digital subtraction angiography (DSA) and/or computed tomography angiography(CTA). (3)Retrospectively,we compared the results of TCD with those of DSA and/or CTA.and tried to find out whether the TCD parameters can be used to estimate the degree of carotid stenosis. Results (1)The more severe of stenosis,the more PSV on stenos-tic segment of ICA1 (PSVICAI) and PSV on carotid occlusion was vanished or20cm/s,no obvious changes of PSV on mild stenosis was found. (2)PSVICA1 /PS VICA2: severe carotid stenosis,3. 13-4. 56(3. 85±1. 98);moderate carotid stenosis,2. 24-2. 73(2. 49±0. 67);mild carotid stenosis.no obvious changes. (3)Collateral supply:The more severe of stenosis,the higher data of collateral circulation supply occurred. It occurred in 93. 1%(27/29) cases suffered from carotid occlusion,in 86. 6%(13/15)cases suffered from 90% carotid stenosis,and in 74. 3%(26/ 35) cases suffered from 70% - 90% carotid stenosis. No collateral supply was found in moderate and mild ICA stenosis. Conclusion (1)TCD may be used to diagnose the extracranial carotid stenosis and to evaluate the degree of stenosis. (2)PSV on stenostic segment of ICA1,ratio of PSVIcA1/ PSVICA2and exsistence of collateral supply may be considered as 3 important TCD parameters for evaluating the degree of carotid stenosis. (3)TCD may be used as a screening tool for DSA or CTA,so that we can choose patients for carotid endarterectomy or invasive therapy with stending.