Measuring the effect of aging on vibrations of the carotid artery wall using empirical mode decomposition method

Abstract

Quantification of arterial elasticity and its dependency to age is considered in this paper. We use radiofrequency (RF) signals from carotid artery ultasonography to evaluate this dependency. Blood pressure, blood flow, and tethering to surrounding tissue are the main causes of the motion of the carotid wall. Tracking carotid artery wall motion from a series of ultrasound B-mode images is challenging due to the presence of noise and variable contrast. Moreover, the process of converting RF signals into the B-mode images causes some information to be lost. Hence, our goal is to extract the carotid wall motions and vibrations from RF signals. After extraction and removing the wall motion by using the phased tracking method combined with continuous wavelet transform, the vibrations of carotid inner wall in different subjects in different ages are compared with each other. Empirical mode decomposition method is used for extracting the first intrinsic mode function for different subjects' vibration and then their zero-crossing rates are compared. The results show the vibrations of the carotid inner wall are clearly decreased by age.