COMPUTED TOMOGRAPHY ANGIOGRAPHY IN THE EVALUATION OF EXTRACANIAL CAROTID ARTERY STENOSIS

Abstract

The risk of stroke associated with symptomatic carotid artery disease is related to the degree of its narrowing. The studies of North American Symptomatic Carotid Endarterectomy (NASCE) has proven that patient with severe stenosis (70-99%) benefit from carotid endarterectomy, therefore determination of the degree of stenosis is very important (Link et al., 1997). Catheter angiography, up till know is the standard of reference. CCDS and MRA are non-invasive tools but they have certain drawbacks. CCDS combined with spectral analysis yield an accuracy of 95% to differentiate carotid occlusion from critical stenosis when compared to catheter angiography. However, sonography is highly operator dependent, and can't be easily presented at film reading sessions before and after surgery, also calcification can degrade the image and obscure the lumen completely (Marks et al., 1993). MRA like CCDS are physiologic examination of the blood vessels, so they image the vessels on more complex phenomena. MRA has been found to show artifactualloss of signal distal to severe stenosis.