CAROTID DOPPLER ULTRASOUND CRITERIA FOR INTERNAL CAROTID-ARTERY STENOSIS BASED ON RESIDUAL LUMEN DIAMETER CALCULATED FROM EN-BLOC CAROTID ENDARTERECTOMY SPECIMENS

Background and Purpose Carotid duplex ultrasound is widely used to scr een patients for carotid endarterectomy and if combined with MR angiog raphy and transcranial Doppler may be an alternative to conventional a ngiography in the preoperative assessment. We have examined the correl ation between Doppler velocities and the residual lumen diameters of i nternal carotid arteries from surgical pathological specimens to estab lish Doppler criteria for residual lumen diameter independent of perce nt stenosis. Methods Ninety-one patients who underwent 99 carotid enda rterectomies for internal carotid artery stenosis within 6 months of t heir carotid duplex ultrasound evaluation were studied. The endarterec tomy specimens were removed en bloc, and the minimal residual lumen di ameter was calculated by computer analysis. The sensitivity and specif icity of the Doppler criteria for determining high-grade stenosis were calculated and receiver-operator curves generated. Results Peak systo lic velocity (PSV), end-diastolic velocity (EDV), and carotid index (p eak internal carotid artery velocity/common carotid artery velocity) c orrelated with the residual lumen diameter. PSV > 440 cm/s, EDV > 155 cm/s, or carotid index > 10 indicated a residual lumen diameter of les s than or equal to 1.5 mm (specificity of 100% and sensitivity of 58%, 63%, and 30%, respectively). When these criteria were combined the se nsitivity increased to 72%. A PSV > 200 cm/s combined with either an E DV > 140 cm/s or a carotid index > 4.5 has a sensitivity of 96% and a specificity of 61%. Conclusions Doppler criteria can be both specific and sensitive for detecting a significant stenosis, defined as a less than or equal to 1.5 mm residual lumen diameter. By adjustment of the velocity criteria, it can be 100% specific or a highly sensitive test (96%).