Evaluation of diffusion parameters and T2 values of the masseter muscle during jaw opening, clenching, and rest

BackgroundDiffusion-weighted imaging (DWI) and diffusion-tensor imaging (DTI) can be used to evaluate changes that accompany skeletal muscle contraction.PurposeTo investigate whether jaw opening or closure affect the diffusion parameters of the masseter muscles (MMs).Material and MethodsEleven healthy volunteers were evaluated. Diffusion-tensor images were acquired to obtain the primary (λ1), secondary (λ2), and tertiary eigenvalues (λ3). We estimated these parameters at three different locations: at the level of the mandibular notch for the superior site, the level of the mandibular foramen for the middle site, and the root apex of the mandibular molars for the inferior site.ResultsBoth λ2 and λ3 during jaw opening were significantly lower than that at rest at the superior (P = 0.006, P < 0.0001, respectively) and middle site (P = 0.004, P = 0.0001, respectively); however, the change in λ1 was not significant. At the lower site, no parameter was significantly different at rest and during jaw opening. The...