CAROTID PLAQUE CHARACTERIZATION USING DIGITAL IMAGE-PROCESSING AND ITS POTENTIAL IN FUTURE STUDIES OF CAROTID ENDARTERECTOMY AND ANGIOPLASTY

Purpose: To corroborate the validity of a computerized methodology for evaluating carotid lesions at risk for stroke based on plaque echogen icity. Methods: The records of 96 carotid endarterectomy patients (59 men; median age 69.5 years, range 52 to 83) with stenoses > 50% were s tudied retrospectively. Forty-one patients (43%) had been symptomatic preoperatively. All patients had undergone computed tomography (CT) to detect infarction in the carotid territory and a duplex scan to measu re carotid stenosis. Plaque echogenicity was analyzed by computer, exp ressing the echodensity in terms of the gray scale median (GSM). The i ncidence of CT-documented cerebral infarction was analyzed in relation to symptomatology, percent stenosis, and echodensity. Results: Sympto ms correlated well with CT evidence of brain infarction: 32% of sympto matic patients had a positive CT scan versus 16% for asymptomatic plaq ues (p = 0.076). The mean GSM value was 56 +/- 14 for plaques associat ed with negative CT scans and 38 +/- 13 for plaques from patients with positive scans (p < 0.0001). However, there was no difference in the GSM value between plaques with > or < 70% stenosis. Furthermore, the i ncidence of CT infarction was 40% in the cerebral territory of carotid plaques with a GSM value < 50 and only 9% in those with a GSM > 50 (p < 0.001). Conclusions: Computerized analysis of plaque echogenicity a ppears to provide clinically useful data that correlates with the inci dence of cerebral infarction and symptoms. This method of analyzing pl aque echolucency could be used as a screening tool for carotid stent s tudies to identify high-risk lesions better suited to conventional sur gical treatment.