Multi-parametric MR in Becker muscular dystrophy patients.

Area of Science:

• Biomedical Imaging
• Musculoskeletal Research
• Neuromuscular Disorders

Background:

• Quantitative MRI and MRS are vital for assessing pathophysiological changes in Becker muscular dystrophy (BMD).
• While muscle fat fraction correlates with function in BMD, reduced muscle strength per unit area suggests impaired non-fat-replaced (NFR) muscle quality.
• There is a need for markers reflecting intrinsic muscle tissue changes in BMD.

Purpose of the Study:

• To explore water T2 relaxation times, diffusion parameters, and phosphorus metabolic indices as potential early disease markers in BMD.
• To compare these quantitative MRI and MRS measures in fat-replaced (FR) and NFR muscles between BMD patients and healthy controls.

Main Methods:

• Quantitative proton MRI (three-point Dixon, multi-spin-echo, diffusion-weighted spin-echo echo planar imaging) and 2D chemical shift imaging 31P MRS were performed.
• Data were acquired from 24 BMD patients and 13 healthy controls, assessing six lower leg muscles.
• Muscle fat fractions, phosphorus metabolic indices, water T2 relaxation times (average and SD), and diffusion tensor imaging (DTI) parameters were analyzed.

Main Results:

• Increased phosphodiester levels were observed in specific NFR and FR muscles (tibialis anterior, peroneus, gastrocnemius lateralis).
• Increased T2 standard deviation (SD) was prevalent in FR muscles compared to NFR and control muscles, indicating T2 heterogeneity.
• No significant differences were found in average water T2 relaxation times or DTI indices between BMD patients and controls.

Conclusions:

• Increased T2 heterogeneity and altered metabolic indices, particularly in more diseased muscles, may serve as early indicators of BMD progression.
• Diffusion tensor imaging (DTI) parameters did not show significant differences between groups in this study.
• Quantitative MRI and MRS, specifically T2 heterogeneity and metabolic changes, hold promise for monitoring muscle tissue quality in BMD.