RF Ultrasound Based Longitudinal Motion Estimation of Carotid Artery Wall: Feasibility Study

Abstract

Arteriosclerosis is a chronic, systemic, inflammatory disease of arteries. Arteriosclerosis reveals itself when complications when as constricted artery lumen and (or) its thrombosis, enlarged and thinner wall (aneurysm) build up. Nonetheless, it has been proved than significant changes of the mechanical properties of common carotid artery (CCA) wall are present much earlier than the anatomical changes appear. The aim of this work is to propose and evaluate an algorithm for analysis of longitudinal and radial movements of CCA wall from registered radiofrequency (RF) ultrasound (US) signals. The proposed method uses RF US signals, phase correlation and sub-sample algorithm to estimate radial and longitudinal movements of CCA wall which was monitored continuously for four cardiac cycles. A physical phantom and in vivo test were employed for testing the algorithm. The results with phantom show that a normalized root mean square error (NRMSE) of detected motion amplitude is from 0.21 to 0.41 μm and the coefficient of correlation is from 0.95 to 0.98 in case of any determined longitudinal motion function when the phase correlation, sub-pixel algorithm and additional filtering were used. The results from this validation study demonstrate the feasibility of CCA longitudinal and radial movement assessment in vivo using phase correlation and sub-sample algorithm. Radiofrequency ultrasound signals algorithm could be used to characterize radial and longitudinal displacements in early stage arteriosclerotic artery.