Over the last decade, MR Fingerprinting (MRF) has emerged as an effective paradigm for the rapid and simultaneous quantification of several parameters using MRI. This method was adapted in 2020 by the NMR Laboratory – Spectroscopy Laboratory at the Institute of Myology to measure parameters that are interesting biomarkers in neuromuscular disorders: water T1 as an early marker of disease activity, and fat fraction (FF) related to the progression of the disease. However, measuring these parameters in the upper body is challenging due to respiratory motion.
In this recent article, researchers from the NMR laboratory at the Institute of Myology, in collaboration with Siemens Healthineers, proposed a new motion-corrected MR Fingerprinting method, MoCo MRF T1-FF. MoCo MRF T1-FF is a modular approach, which first measures the breathing deformations using AI methods, and then uses them to correct motion in the reconstruction of parametric maps for FF and water T1.
To validate this approach, the authors used in vivo data collected from 18 healthy volunteers (12 men, 6 women, mean age = 40 ± 14 years) and 3 subjects suffering from various neuromuscular disorders.
In regions unaffected by motion, such as the dorsal or pectoral muscles, no bias was observed between the uncorrected reconstructions and the reconstructions provided by MoCo MRF T1-FF for FF and T1 water values. Furthermore, MoCo MRF T1-FF significantly reduced the standard deviations of the parameter distributions evaluated in these regions, indicating an improvement in accuracy.
In regions strongly affected by respiration, such as the respiratory muscles, liver and kidneys, the maps obtained by MoCo MRF T1-FF showed a marked reduction in movement-related artefacts (blurring, streaking, etc.). Finally, the diaphragm, generally invisible on parametric maps, appeared after motion correction.
The authors conclude that this new approach paves the way for the joint assessment of the potential of fat fraction and water T1 in muscles that are rarely assessed, such as the diaphragm, and for the multi-systemic evaluation of neuromuscular diseases.
