Lower extremity magnetic resonance imaging (MRI), including diffusion-tensor imaging, may provide valuable information on skeletal muscle abnormalities in patients with type 2 diabetes mellitus (T2DM) with or without diabetic polyneuropathy, according to study results published in Radiology.
Up to 50 percent of patients with long-term diabetes develop diabetic polyneuropathy, which may be associated with skeletal muscle abnormalities. Previous studies suggested that MRI can be used as a noninvasive measure of skeletal muscle abnormalities. The objective of the current study was to evaluate skeletal muscle abnormalities using MRI in patients with T2DM with or without diabetic polyneuropathy.
This prospective, cross-sectional study included 20 patients with T2DM and diabetic polyneuropathy (mean age, 65 years; 70% men), 20 subjects with T2DM without diabetic polyneuropathy (mean age, 64 years; 55% men), and 20 healthy control participants (mean age, 61 years; 55% men). All participants completed isokinetic dynamometry to assess muscle strength at the knee and ankle and an MRI of the lower extremities.
Data showed that patients with diabetes and neuropathy had lower muscle strength in the upper and lower leg compared with patients with diabetes without neuropathy and healthy control participants. In patients with diabetic polyneuropathy, the maximal isokinetic muscle strength was lower for knee extensors (73% vs 95% vs 93%, respectively; P <.001), plantar flexors (62% vs 78% vs 89%, respectively; P <.001), and dorsal flexors (81% vs 98% vs 107%, respectively; P =.001) than in patients with diabetes without neuropathy and healthy control participants.
Diffusion-tensor imaging calculated that fat fractions were higher in leg muscle groups of patients with diabetic polyneuropathy than in patients with diabetes without neuropathy and healthy control participants. The T2 relaxation of muscle was prolonged in all muscle groups of patients with diabetic polyneuropathy compared with healthy control participants (P <.001).
Multivariate regression models showed that T2 relaxation of muscle, Dixon fat fraction, and fractional anisotropy increased with the degree of neuropathy at the lower leg (P <.001), and increased with impaired muscle strength (P <.001) and degree of neuropathy (P <.007) at the upper leg.
The study had several limitations, including small effect sizes of diffusion tensor imaging parameters, inclusion of patients with only mild to moderate diabetic neuropathy, and a relatively small sample size.
The study researchers concluded that “lower extremity MRI, including Dixon imaging, T2 relaxation of muscle, and fractional anisotropy, depicted fat accumulation, change in muscle water content, and structure in participants with type 2 diabetes.”
Stouge A, Khan KS, Kristensen AG, et al. MRI of skeletal muscles in participants with type 2 diabetes with or without diabetic polyneuropathy. Radiology. Published online October 13, 2020. doi:10.1148/radiol.2020192647