Effects of Diffusion Tensor Imaging B-Value on the Quantification of Lower Leg Skeletal Muscle Fascicle Architecture in Humans

An important determinant of skeletal muscle contractile function is the arrangement of fibres within the muscle belly, which can be determined using diffusion-weighted MR imaging (DWI). DWI acquisition protocols can be optimised to maximize the image quality through manipulation of the b-value parameter. However, systematic, objective assessment of the effects of different b-values on measures of skeletal muscle architecture is scarce. Diffusion weighted images of medial gastrocnemius (MG), tibialis anterior (TA), and lateral gastrocnemius (LG) muscles were acquired from six healthy adults, with b-values ranging from 10 to 500 s/mm2. In general, mean fascicle length, pennation angle, curvature, and diffusivity values were consistent when b-values were greater than 100 s/mm2. The b-value influenced the variation in architecture and diffusivity quantified, with specific changes in variance differing between the muscles studied.