A simple, non-dimensional, normalized common carotid Doppler velocity wave-form index that identifies patients with carotid stenosis.

A non-invasive Doppler velocity index that is specific for carotid artery stenosis is presented. The index is both non-dimensional (maximum/minimum velocity to remove within artery Doppler signal variability) and normalized (larger over smaller carotid maximum/minimum ratio to minimize between patient variability). Of 260 normal patients 94% had a maximum/minimum index between 1.00 and 1.25 and 97.5% had an index between 1.00 and 1.30. In 136 patients undergoing selective carotid arteriography the overall accuracy of the maximum/minimum index in predicting carotid stenosis was 85-87%. When 1.30 is taken as the maximum normal index value the test is 96.5% specific and 76% sensitive. The receiver operating characteristic curve indicates that patients with a maximum/minimum index greater than 1.4 have a 99% probability of significant carotid stenosis.