Cardiac Magnetic Resonance Elastography of the Mouse: Initial Results

Abstract

Purpose

Many cardiovascular diseases are associated with abnormal function of myocardial contractility or dilatability, which is related to elasticity changes of the myocardium over the cardiac cycle. The mouse is a common animal model in studies of the progression of various cardiomyopathies. This article introduces a novel non-invasive approach using microscopic scale magnetic resonance elastography to measure the myocardium stiffness change during the cardiac cycle on a mouse model.

Methods

A harmonic mechanical wave of 400 Hz was introduced into the mouse body. An electrocardiograph-gated and respiratory-gated fractional encoding cine-MRE pulse sequence was applied to encode the resulting oscillatory motion on a short-axis slice of the heart. Five healthy mice ages from 3 to 13.5 months were examined. The weighted summation effective stiffness of the left ventricle wall during the cardiac cycle were estimated.

Results

Results show the ratio of stiffness at end-diastole (ED) and end-systole (ES) in a range of 0.5 to 0.67. Additionally, variation in shear wave amplitude in the left ventricle wall throughout the cardiac cycle was measured and found to correlate with estimates of stiffness variation.

Conclusion

This study demonstrates the feasibility of implementing cardiac MRE on a mouse model.