The stiffness parameter β assessed by an ultrasonic phase-locked echo-tracking system is associated with plaque formation in the common carotid artery

Purpose: Assessment of plaque formation in the common carotid artery (CCA) is important for stratification of the risk of subsequent stroke. The stiffness parameter β, which can be assessed using an ultrasonic phase-locked echo-tracking system, was developed to evaluate arterial stiffness. The purpose this study was to examine the relationship of the stiffness parameter β to intima-media thickness (IMT) and plaque formation. Methods: The stiffness parameter β and mean IMT were measured using an ultrasonic phase-locked echo-tracking system and an automatic IMT measurement system, respectively, and the presence of plaque was assessed by ultrasonography in 347 subjects who took part in a health check-up program for community-dwelling people in Hokkaido. Results: Values of the stiffness parameter β were significantly higher in subjects with plaque formation than in those without plaque (10.60 ± 0.45 vs. 8.88 ± 0.23, P < 0.005) in whom IMT was not thickened; however, it was not different in subjects with increased IMT (>1.0 mm). The percentage of plaque formation was significantly correlated with the value of the stiffness parameter β. Furthermore, the stiffness parameter β was significantly correlated with plaque formation after adjustment for several clinical variables (odds ratio 1.113-1.178, P < 0.001). Conclusion: The stiffness parameter β is associated with plaque formation in the CCA, especially in subjects with a normal IMT. This could potentially be used as a predictor for plaque formation.