NONINVASIVE IMAGING MODALITIES IN DECISION MAKING ABOUT CAROTID ENDARTERECTOMY – A COMPARISON OF DUPLEX ULTRASOUND, CT- AND MR-ANGIOGRAPHY

Purpose: Determining degree and morphology of stenoses is important for surgical planning, but controversy remains regarding the optimal preoperative evaluation to facilitate patient selection for carotid endarterectomy.

Angiography (DSA) is considered to be the “gold standard“ for confirmation, but is also associated with a procedural risk of stroke up to 1%. Aim of the study was to compare the diagnostic accuracy of noninvasive, preoperative imaging modalities for evaluation of carotid artery stenosis.

Methods and Materials: In a consecutive series of patients with high-grade stenoses (70–99%) detected by color-coded duplex ultrasonography (US) subsequent multi-slice computed tomographic angiography (CTA) and contrast-enhanced magnetic resonance angiography (MRA) were performed. Data provided by preoperative methodologies were compared with the surgically removed specimens regarding to degree of stenosis, plaque morphology and presence of ulcerations.

Results: 27 patients (78% male) with severe carotid stenosis (30% symptomatic) with a mean age of 69.4 years undergoing endarterectomy were involved.

The rates of stenosis degree obtained by US proved to be very accurate with respect to surgical evidence (sensitivity 100%). In comparison with intraoperative evidence CTA correctly classified the degree of stenosis in 26/27 cases (=96%), underestimating one case as moderate stenosis. MRA were in agreement in 24/27 cases (=89%). Underestimation occurred in one case as mild and in two as moderate stenosis.

Conclusions: In patients with carotid atherosclerotic disease, who are surgical candidates, duplex sonography is a very accurate modality for identification of stenosis degree and detection of ulcerated plaques. CTA and MRA occasionally underestimate lumen stenosis degree. Thus, CTA/MRA are a good screening method, but because of infrequent lack to reliably distinguish between moderate and severe stenosis, which is important in treatment of carotid stenosis, they could replace conventional angiography before surgery only in combination with US.

In conclusion, vascular ultrasound should usually be the first modality to evaluate carotid artery stenosis before carotid endarterectomy. CTA and MRA are recommended as second-level examination, except of some particular indications, e.g. differentiating critical stenosis (near-occlusion) from complete occlusion.