Free-breathing Magnetic Resonance Fingerprinting for fat fraction and water T1 quantification of upper body muscles

Motivation: Respiratory muscles are often altered in subjects with neuromuscular diseases. Characterizing their structure using quantitative MRI is then crucial but challenging due to respiratory motion. Goal(s): We developed a 3D free-breathing Magnetic Resonance Fingerprinting sequence for quantifying fat fraction (FF) and water T1 (T1H2O) of upper body muscles at 3T. Approach: We estimated the free-form respiration motion deformation on a 3D pre-scan using VoxelMorph and subsequently applied it in an iterative reconstruction framework to retrieve the MRF image series. Results: This method allows a significant reduction of motion artefacts on parametric FF and T1H2O maps. Impact: Free-breathing MRF T1-FF on 3T scanners paves the way for high resolution quantification of FF and T1H2O in the upper body muscles for monitoring their structural alterations in subjects with neuromuscular diseases with high precision.