Significance of sonographic tissue and surface characteristics of carotid plaques

BACKGROUND AND PURPOSE: Our hypothesis was that symptomatic and asymptomati c carotid plaques are different. The aim of this study was to identify the sonographic tissue and surface characteristics of plaques and their degree of stenosis that corresponded to these two clinical presentations. METHODS: We studied 81 symptomatic and 111 asymptomatic plaques (150 patien ts) having 50% to 99% stenosis on duplex scanning. These plaques were image d on duplex and captured in a computer. We evaluated the gray-scale median (GSM) to distinguish hypoechoic (low GSM) from hyperechoic (high GSM) plaqu es, and the bending energy (BE), to distinguish plaques with irregular (hig h BE) versus smooth (low BE) surfaces. RESULTS: The symptomatic group corresponded to hypoechoic (median GSM, 4) a nd severely stenosed (median stenosis, 85%) plaques, whereas the asymptomat ic group corresponded to hyperechoic (median GSM, 35) and moderately stenos ed (median stenosis, 70%) plaques (P < .05 for both variables). The BE fail ed to separate the two groups; the mean BEs were 1.63 and 1.68 for the symp tomatic and asymptomatic groups, respectively (P = .38). CONCLUSION. Our results suggest that echogenic characteristics and the degr ee of stenosis are the strongest predictors of carotid plaque behavior. The sonographic surface characteristics failed to qualify as an index of plaqu e instability.