P6.09 ULTRASONOGRAPHIC MEASUREMENT OF ARTERIAL WALL AND INTRAPLAQUE STRAIN IN THE CAROTID BULB AND COMMON CAROTID ARTERY

Abstract

Background: Transient ischemic attacks and stroke are commonly caused by vulnerable plaques in the carotid bulb. Noninvasive ultrasound imaging techniques, revealing spatial inhomogeneities in strain distribution, could possibly improve the timely diagnosis of plaque at risk of rupturing. Methods: In 20 subjects with cerebrovascular ischemia, radiofrequency ultrasound data, covering 20 by 24mm, of the carotid bulb and distal common carotid artery (CCA) were twice and bilaterally recorded during 6 cardiac cycles to assess 2D wall strain rate distribution at radial and lateral increments of 0.45mm and 1.8mm, respectively at peak distension rate. Results: Reproducible strain rates were obtained for distal CCA and carotid bulbs free of plaques (unilateral intrasubject variation of 1.1±0.6%/s and 1.2±0.7 %/s, respectively). Strain rate was generally higher in the distal CCA (7.5±3.9%/s) than in carotid bulb (3.4±2.5%/s). Strain inhomogeneity was significantly associated to plaque area (p<0.001) and was lower in distal CCA (1.2±0.6) than in carotid bulb (1.6±1.0). Discussion: High resolution strain distribution in carotid segments reveals inhomogeneities in mechanical characteristics of the artery wall, and of the carotid artery plaques. Strain in the distal CCA is different in magnitude and inhomogeneity from the strain in the carotid bulb. Therefore, the proposed method for noninvasive identification of wall composition using ultrasonography might be a powerful tool to assess the plaque burden in an arterial segment particularly prone to plaque formation.