Time-dependent diffusion in muscle can be imaged in a clinically feasible scan time with modern clinical magnetic resonance imaging (MRI) equipment, showed a study by researchers in the UK and Germany published in the journal Magnetic Resonance in Medicine. Moreover, there were distinct differences in diffusion metrics between patients with Duchenne muscular dystrophy (DMD) and age-matched healthy controls.
“These results could be used to optimize diffusion imaging in this disease further and imply that these diffusion indices may become an important biomarker in monitoring progression in DMD in the future,” stated first author Amy R. McDowell and the co-authors of the study.
The clinical course of DMD varies greatly from one patient to the other. Fat-fraction and muscle T2-signal intensities have been proposed as noninvasive biomarkers, making MRI an important tool to monitor the progression of the disease.
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In order to characterize the diffusion time-dependence in muscle in a clinically feasible acquisition time in children, the team acquired diffusion data from muscles of boys with DMD and healthy controls. To do so, they used a pulsed gradient stimulated echo diffusion preparation at 5 different diffusion times, 4 different b-values, and 6 directions. They then processed the data to obtain standard diffusion indices and fractional anisotropy at each diffusion time.
The results showed there was time-dependent diffusion in the muscle of healthy adult volunteers as well as children with DMD and age-matched controls. The mean diffusivity was reduced and the fractional anisotropy was increased in boys with DMD across a range of diffusion times, with the largest effect size obtained at a diffusion time of 190 ms.
The researchers said that further studies are necessary in a larger group of people to comparing the data with existing MRI biomarkers, such as T-mapping and Dixon fat-water imaging.
Reference
McDowell AR, Feiweier T, Muntoni F, Hall MG, Clark CA. Clinically feasible diffusion MRI in muscle: time dependence and initial findings in Duchenne muscular dystrophy. Magn Reson Med. Published online August 2, 2021. doi:10.1002/mrm.28945
