The patho-physiological sensitivity of cardiac MR elastography: Preliminary results

Introduction: Elastography is capable to directly measure tissue stiffness and therewith to provide a quantitative method for ‘palpating’ internal organs [1]. This is particularly interesting for cardiac applications since function is here based on the alteration of the stiffness, i.e. the shear modulus of the myocardium. Recently, cardiac MR elastography (MRE) was demonstrated by measuring elasticity changes during the cardiac cycle in pigs and healthy volunteers [2-4]. Problem: So far cardiac MRE was only tested on animals and healthy volunteers. Up to now the amplitudes of shear waves inside the left ventricle (LV) have been evaluated with respect to their systolic values. Amplitude-based elastography requires normalization in order to deduce a generalized metric independent of experimental conditions and individual variations. No such metric has been proposed for diagnostic applications of cardiac MRE. Objective: Normalized LV-shear wave amplitudes are measured in healthy volunteers (n = 11) and in patients with cardiac pathology (n = 11) to test the hypothesis that an increase in myocardial stiffness causes a decrease in wave amplitudes detectable by MRE.