[Role of 0.5 T magnetic resonance and duplex ultrasonography in the imaging of stenotic and oblitertive changes in the carotid arteries].

The aim of the study was to determine diagnostic value of magnetic resonance angiography (MRA) of the carotid artery, performed with less expensive machine of 0.5 T, and value of duplex ultrasonography (DU) in the same patients. Diagnostic values of MRA and DU were examined by comparison with the results of digital subtraction angiography (DSA) or with the operative finding. All MRA examinations were performed in the same diagnostic center, but DU diagnostic procedures were performed in five different centres. In total, we examined 70 arteries in 37 patients. Among them, 66 arteries in 33 patients were compared with DSA and four arteries in four patients with operative findings. All patients were referred to DSA after MRA and DU. In four patients four carotid arteries were operated without DSA due to previous allergic reaction to iodinated contrast agent. The positive result in present examination was stenosis of the carotid artery more than 70% of the arterial lumen. Such stenosis is considered as an indication for active therapeutic approach using vascular surgery or transluminal angioplasty. Results indicate more true positive results for MRA (21 patients) than for DU (20 patients). Also, we found more true negative results for MRA (45 patients) than for DU (44 patients). MRA had one false positive and three false negative results, and DU two false positive and 4 false negative results. Sensitivity of MRA in our group of patients was 88% and specificity 98%. In the same group DU had sensitivity 83% and specificity 96%. Our results showed that neither MRA nor DU separately could replace DSA in diagnosis of high grade carotid stenosis. Because of high specificity, negative MRA or DU can exclude significant stenosis and avoid DSA. In the case of similar positive results of MRA and DU, the number of DSA can be reduced.