ASSESSMENT OF CAROTID-ARTERY STENOSIS BY ULTRASONOGRAPHY, CONVENTIONAL ANGIOGRAPHY, AND MAGNETIC-RESONANCE ANGIOGRAPHY - CORRELATION WITH EX-VIVO MEASUREMENT OF PLAQUE STENOSIS

Purpose: Several studies have investigated the correlation between Dop pler ultrasonography (DUS), angiography (CA), and magnetic resonance a ngiography (MRA) in the evaluation of stenosis of the carotid bifurcat ion. However, these studies suffer from the lack of a true control-the lesion itself-and therefore conclusions about the diagnostic accuracy of each method remain relative. To determine the absolute accuracy of these modalities, we have prospectively studied lesion size with DUS, MRA, and CA in 28 patients undergoing 31 elective carotid endarterect omies and compared the percent of carotid stenosis determined by each technique to the carotid atheroma resected en bloc. Methods: All patie nts were evaluated by each modality within 1 month before the thromboe ndarterectomy. With DUS, stenosis size was determined by standard flow criteria. For angiography and MRA, stenosis was defined as residual l umenal diameter/estimated normal arterial diameter (European Carotid S urgery Trial criteria). At surgery the carotid atheroma was removed en bloc in all patients. Patients in whom the lesion could not be remove d successfully without damage were excluded from the study. Stenosis o f the atheroma was determined ex vivo with high-resolution (0.03 mm(3) ) magnetic resonance and confirmed by acrylic injection of the specime n under pressure and measurement of the atheroma wall and lumen. Resul ts: The measurements of the ex vivo stenosis by high-resolution magnet ic resonance imaging correlated closely with the size of stenosis dete rmined by the acrylic specimen casts (r = 0.92). By ex vivo measuremen t, the lesions were placed in the following size categories: 40% to 59 % stenosis (n = 2), 60% to 79% stenosis (n = 6), 80% to 89% stenosis ( n = 7), and 90% to 99% stenosis (n = 16). Conclusions: In general, the correlation of measurements of ex vivo stenosis with all modalities w as good in these severely diseased arteries, although it was better fo r DUS (r = 0.80; p < 0.001) and MRA (r = 0.76; p < 0.001) than for CA (r = 0.56; p < 0.05).