Diffusion tensor imaging in biomechanical studies of skeletal muscle function

In numerical simulations of skeletal muscle contractions, geometric informa tion is of major importance. The aim of the present study was to determine whether the diffusion tensor imaging (DTI) technique is suitable to obtain valid input with regard to skeletal muscle fibre direction. The accuracy of the DTI method was therefore studied by comparison of DTI fibre directions in the rat tibialis anterior muscle with fascicle striation patterns visib le on high-resolution magnetic resonance imaging (MRI) and with fibre direc tions in an actual longitudinal section (ALS) through the same muscle. The results showed an excellent qualitative agreement between high-resolution M RI and DTI. Despite less accurate quantitative comparison with ALS, it was concluded that DTI does indeed measure skeletal muscle fibre direction. Aft er the experiment, it was possible to determine an appropriate voxel size ( 0.9 mm(3)) that provided enough resolution and acceptable accuracy (5 degre es) to use DTI fibre directions in biomechanical analyses. Muscle deformati on during contraction, resulting from a finite element simulation with a me sh that was directly generated from the experimental data, has been present ed.