Reproducibility of Cardiac Multifrequency MR Elastography in Assessing Left Ventricular Stiffness and Viscosity

Area of Science:

• Cardiovascular Imaging
• Biomedical Engineering
• Medical Physics

Background:

• Cardiac magnetic resonance elastography (MRE) offers potential for evaluating heart mechanics.
• Clinical application is hindered by challenges in synchronization with cardiac cycles, breathing, and external stimulation.
• Multifrequency MRE (MMRE) aims to overcome these limitations.

Purpose of the Study:

• To assess the reproducibility of in vivo cardiac multifrequency MRE (MMRE).
• To evaluate MMRE's capability in measuring diastolic left ventricular (LV) stiffness and viscosity.

Main Methods:

• Prospective, single-center study involving 28 participants (healthy and aortic stenosis patients).
• Utilized 3T, 3D multifrequency MRE with a spin-echo planar imaging sequence.
• Acquired 3D wave fields in diastole at 80, 90, and 100 Hz over three breath-holds.
• Analyzed shear wave speed (SWS) and penetration rate (PR) for stiffness and viscosity, using Bland-Altman and ICC for reproducibility.

Main Results:

• High test-retest reproducibility for MMRE measurements of LV myocardial stiffness (ICC=0.96) and viscosity (ICC=0.93).
• Mean SWS values were 2.42±0.24 m/s (scan) and 2.39±0.23 m/s (re-scan).
• Mean PR values were 1.24±0.17 m/s (scan) and 1.22±0.14 m/s (re-scan).
• Excellent inter-reader agreement for stiffness (ICC=0.92) and viscosity (ICC=0.85).

Conclusions:

• Cardiac MMRE demonstrates high reproducibility for assessing diastolic LV stiffness and viscosity.
• The method is a promising tool for noninvasive evaluation of myocardial mechanical properties.
• MMRE offers a reliable approach to quantify diastolic LV function.