Skeletal muscle deformation analysis using diffusion tensor Magnetic Resonance imaging

Skeletal muscles are highly organized tissues formed of fiber bundles packed together. Muscle fibers have distinct orientations which makes them a favorable subject for diffusion tensor imaging (DTI) based analyses. DTI provides in vivo measures revealing the structural characteristics of tissues based on diffusion anisotropies of water molecules within structures. Local fiber orientations can be extracted for deformation analysis of the spatial distribution of diffusion and strain characteristics along fiber directions. This work aims to present a framework for the assessment of local strain and diffusion anisotropy changes as skeletal muscles of human subjects (n=3) become deformed by moving from a flexed configuration (150 degrees knee angle) to an extended configuration (180 degrees knee angle). Changes between the diffusion anisotropy indices and strain coefficients along fiber tracts between the tibialis anterior muscle ends are computed, visualized and modeled to account for heterogeneous changes in the microstructure resulting from deformation. Results are indicators of effects of myofascial force transmission on human muscles in vivo, including local differences between sarcomere length changes (maximal lengthening and shortening equals 34.62% and -33.78%, respectively) and diffusivity changes in the proximo-distal direction as well as in the transverse plane. The demonstrated methodology also provides an image processing toolbox for the thorough analysis of skeletal muscles. Final results presented here can have clinical implications by contributing to explaining and improving the treatment options of movement limitations.