Magnetic Resonance Elastography through Atherosclerosis: A Feasibility Study

It is widely acknowledged that assessing the rupture risk of atherosclerotic plaques, via lumen reduction, is an imperfect criterion and that other properties such as those related to biomechanics may be more relevant. This study investigated the hypothesis that magnetic resonance elastography (MRE) can be used to image the elasticity of atherosclerotic plaques with the aim to give a better indication of rupture risk. Atherosclerotic plaques were imaged through a small feasibility data set including stenosed arterial phantoms, healthy volunteers and peripheral artery disease (PAD) patients. Comparison of the healthy volunteer and PAD patient wave displacement images showed differences in noise levels, wave amplitudes and wave propagation through the lumen. However, the change in shear moduli through healthy and diseased areas of the phantoms and in vivo subjects could not be detected. Synthetic modelling of the arterial phantoms, under replicated imaging conditions, suggested that there is scope to improve the results through increased control of the phantom and the inclusion of more realistic blood mimic. The MRE wave displacement appeared highly damped through the lumen of the atherosclerotic PAD data sets when compared to the healthy volunteers. This interesting result indicates that the presences of disease, likely to be calcified plaques, are causing changes in the wave propagation that may be captured using MRE. There is scope to clarify the conclusions in this study by developing the technique, particularly the imaging acquisition parameters and inversion algorithm.