Variation of magnetic resonance elastography shear wave behaviour through atherosclerotic plaque with disease development

The clinical assessment of the rupture risk of atherosclerotic plaque is made by imaging the reduction of the lumen; via ultrasound or angiography. It is known that this is an imperfect criterion and that other characteristics of the plaque, such as the change in mechanical properties, may be more relevant. Magnetic Resonance Elastography (MRE) is a novel imaging technique that measures tissue stiffness. Magnetic resonance imaging measures the tissue displacementin response to harmonic shear waves excited on the surface of the body by a vibrating actuator. The images of wave propagation are transformed into an image of stiffness using an inversion algorithm. A steady state analysis was conducted on a simulation of MRE shear waves propagating through anidealised atherosclerotic plaque. The variation of the 2D complex wave response was investigated with regards to stenosis size, lipid pool size and excitation frequency. The detectability of small lipid pools was shown to increase with frequency. However significant wave disruptions were observed at higher excitation frequencies. This study shall form the basis for future work on incorporating an inversion algorithm into the simulation.