Motion artifact reduction in ultrasound based thermal strain imaging of atherosclerotic plaques using time-series analysis

Large lipid pools in vulnerable plaques, in principle, can be detected using ultrasound-based thermal strain imaging (US-TSI). One practical challenge for in vivo cardiovascular application of US-TSI is that the thermal strain is masked by the mechanical strain caused by cardiac pulsation. Electrocardiography (ECG) gating is a widely adopted method for cardiac motion compensation, but it is often susceptible to electrical and physiological noise. In this paper, we present an alternative time-series analysis approach to separate thermal strain from the mechanical strain without using ECG. The performance and feasibility of the time-series analysis technique was tested via numerical simulation as well as in vitro water tank experiments, using a vessel-mimicking phantom and an excised human atherosclerotic artery, for which the cardiac pulsation is simulated by a pulsatile pump.