Free-Breathing, 3D Cardiac Magnetic Resonance Elastography for Myocardial Stiffness Mapping

Area of Science:

• Cardiovascular Imaging
• Biophysics
• Medical Physics

Background:

• Traditional cardiac Magnetic Resonance Elastography (MRE) relies on breath-held scans, limiting anatomical coverage and patient comfort.
• There is a need for advanced MRE techniques that allow for free-breathing acquisitions to improve cardiac imaging efficiency and scope.

Purpose of the Study:

• To investigate the feasibility of a novel 3D, free-breathing cardiac MRE technique.
• To assess the ability to map myocardial stiffness throughout the cardiac cycle using this new method.

Main Methods:

• A 3D hybrid radial and EPI acquisition was employed, coupled with retrospective k-space binning using physiologic monitoring.
• Iterative reconstruction, specialized MRE processing, and cardiac-focused post-processing were utilized.
• Stiffness mapping was performed across seven temporal states of the cardiac cycle.

Main Results:

• Demonstrated feasibility of free-breathing stiffness mapping of the left ventricular myocardium in 11 participants.
• Observed increased myocardial stiffness during systolic states compared to diastolic states, with significant differences detected (p < 0.001).
• Localized stiffness heterogeneity was noted between participants, highlighting the benefit of 3D cardiac MRE. Systolic stiffness changes were more robustly detected than diastolic ones.

Conclusions:

• Established the feasibility of 3D, free-breathing cardiac MRE in healthy volunteers.
• Cardiac MRE stiffness estimation is more robust during systole; diastolic estimates show subject-specific limitations.
• This technique provides a promising avenue for non-invasive assessment of myocardial mechanical properties.