Assessment of in-vivo skeletal muscle mechanics during joint motion using multimodal magnetic resonance imaging based approaches

The aim of this study is to quantify local deformations in the direction of muscle fibers occurred during joint motion by using specific Magnetic Resonance Imaging (MRI) sequences and post-processing tecniques.Data acquisition was performed within the body of preliminary study with the participaton of a 23 years old healthy male subject. Diffusion Tensor (DT) and Phase Contrast (PC) image sets are acquired during the cyclic ankle movement within the 80°-110° ankle angle range (10° dorsiflexion and 20° plantarflexion) and at the frequency of 0.5 Hz. Post processing techniques were used to quantify fiber direction strain distribution for both of the m. Gastrocnemius and m. Soleus. Fiber direction peak lengthening and shortening values for the m. Gastrocnemius were calculated as 7.1% and 30.8%, respectively. However a significant lengthening was not observed for m. Soleus, fiber direction peak shortening value was calculated as 24.6% for the same muscle. In consideration of this findings, it is noticed that the fiber direction strain distribution is significantly heterogeneous.Moreover, coexistence of the local lengthenings and local shortenings within the fiber direction strain distribution is found to be remarkable. From the clinical perspective,these quantified parameters have a significance to understand movement limitations caused by spasticity and contractures which may occur concominantly.