THREE-DIMENSIONAL ULTRASOUND AND STENOSIS OF INTERNAL CAROTID ARTERY

Abstract

Background. Elucidation of the ultrasound structure of the atherosclerotic plaque in stenosis of internal carotid artery may have important implications for carotid surgery. This study compares the ability of computer derived 3D ultrasound gray scale volumetric measurements to diferentiate between ultrasonic structure of symptomatic and asymptomatic carotid plaque causing more than 70% stenosis.Methods. Eightysix internal carotid artery stenoses (70–99%, 45 symptomatic, 41 asymptomatic) were imaged with 3D ultrasound to obtain the whole volume of the atherosclerotic plaque. Digitalized sonograms were computerized and normalized to the gray scale median (GSM) of blood (0) and vessel adventitia (200). Plaque GSM was obtained for the whole volume by computing the volume ratio between echolucent and echogenic areas. The plaque heterogeneity was obtained by computing the density of echogenic areas per volume unit. Parametric t test was used for statistic analysis.Results. Minimum volume GSM ratio (determining echolucency) was higher for asymptomatic plaque (0.6 – CI 0.48– 0.91 versus 0.3 – CI 0.21–0.75: p = 0.002). Greater GSM heterogeneity was present in symptomatic plaque (6.8 – CI 2.5– 18.3 versus 0.41 – CI 0.2–3.4;.p = 0.0001).Conclusions. Volume ultrasound imaging that enables objective assessment of whole ultrasonic plaque structure is more sensitive that single longitudinal view sonography for differentiating between ultrasonic structure of symptomatic and asymptomatic plaque.