NMR in Biomedicine · Jul 12, 2023
Time-dependent diffusion tensor imaging and diffusion modeling of age-related differences in the medial gastrocnemius and feasibility study of correlations to histopathology
By Malis V, Sinha U, Smitaman E et al.
PURPOSE: Implement STEAM-DTI to model time-dependent diffusion eigenvalues using the random permeable barrier model (RPBM) to study age-related differences in the medial gastrocnemius (MG) muscle. Validate diffusion model-extracted fiber diameter for histological assessment. METHODS: Diffusion imaging at different diffusion times (Δ) was performed on seven young and six senior participants. Time-dependent diffusion eigenvalues (λ₂ (t), λ₃ (t), and D⊥ (t); average of λ₂ (t) and λ₃ (t)) were fit to the RPBM to extract tissue microstructure parameters. Biopsy of the MG tissue for histological assessment was performed on a subset of participants (four young, six senior). RESULTS: λ₃ (t) was significantly higher in the senior cohort for the range of diffusion times. RPBM fits to λ₂ (t) yielded fiber diameters in agreement to those from histology for both cohorts. The senior cohort had lower values of volume fraction of membranes, ζ, in fits to λ₂ (t), λ₃ (t), and D⊥ (t) (significant for fit to λ₃ (t)). Fits of fiber diameter from RPBM to that from histology had the highest correlation for the fit to λ₂ (t). CONCLUSION: The age-related patterns in λ₂ (t) and λ₃ (t) could tentatively be explained from RPBM fits; these patterns may potentially arise from a decrease in fiber asymmetry and an increase in permeability with age.