Determination of carotid plaque risk by ultrasonic tissue characterization

This in vitro study investigated the ability of ultrasonic tissue character ization (UTC) to discriminate between plaques from asymptomatic and symptom atic patients and to compare UTC findings with quantitative measurements of plaque morphology. A total of 34 plaque specimens removed at carotid endar terectomy were scanned transversely at intervals of 1 mm, and compared to t issue cross-sections examined by optical microscopy employing computer-assi sted planimetry. UTC was performed by spectral analysis of backscattered ra diofrequency signals. The slope, intercept and total power parameters of th e spectrum were evaluated. Discriminant analysis was used to compare the ab ility of the UTC spectral parameters and morphological constituents to corr ectly classify plaques according to their symptom group membership. UTC cor rectly classified 88.2% of the plaques. Thrombus was present in 93.9% of th e plaques, and there was little difference in the morphological constituent s of plaques from asymptomatic and symptomatic patients. Morphological cons tituents correctly classified 60.7% of the plaques. We conclude, in this pr eliminary study, that UTC can discriminate between carotid plaques from asy mptomatic and symptomatic patients with moderate accuracy, despite a simila rity in their morphological composition. UTC discrimination is not related to differences in the type or amount of morphological constituents in the p laques. (C) 1998 World Federation for Ultrasound in Medicine & Biology.