Résumé :
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An objective assessment of disease progression and muscle damage is required to prove therapies for muscle degeneration. In this context, we propose an objective MRI-based method for the assessment of the Tibias Anterior (TA) muscle degeneration in DM1 patients. 20 patients were included in the study. Lower leg MRI examination was performed subsequent to genetic testing. TA muscular relative isometric strength (i.e. torque muscle) was also assessed for left and right legs using a hand-held dynamometer. 3D high spatial anatomical images were acquired in the transversal orientation, covering the legs from knee to ankle. The same geometric parameters were used to acquire MR images using the following pulse sequences: T1; DP/T2 and 3-point Dixon. An automatic segmentation algorithm was developed in order to delineate between normal and diseased tissues on T1 images. Main T2 value of TA’s normal tissue was assessed from DP/T2 weighted images. Finally, Grey-level average values measured from fat and water images of 3-point Dixon sequence, were used to define fat to water ratio in the TA muscle. Normal and degenerated tissue volumes, oedema severity, quantified as the main T2 value in normal tissue, and fat infiltration, quantified as fat to water ration, were assessed for TA muscles. An excellent correlation was found between normal tissue volume and muscle strength. In this in-progress work, we have validated the use of MRI for quantitative assessment of entire muscle (TA) degeneration in DM1 patients. The muscle composition parameters we proposed could be used as markers for the severity and progression of the disease and for therapy effect quantification.
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