Diffusion tensor imaging (DTI) of human lower leg muscles: correlation between DTI parameters and muscle power with...

To compare diffusion tensor imaging (DTI) parameters in healthy adult human lower leg muscles and to determine the correlation between DTI parameters and muscle power measurements among different types of muscle contraction.

DTI measurements of the unilateral lower leg muscles having three different types of contraction (non-contraction state, isometric contraction, and soleus shortening) were obtained from 10 healthy adults using a 3-T MRI scanner. DTI parameters (λ₁, λ₂, λ₃, mean diffusivity, and fractional anisotropy) were calculated. The values of the DTI parameters and correlation between the DTI parameters and muscle power measurements (maximum power and maximum amount of work) obtained from a dynamometer were statistically compared among the different types of contraction. Intra- and inter-class correlation coefficients were calculated for analysis of reproducibility.

The λ₁, λ₂, λ_3, and mean diffusivity of the soleus muscle are significantly lower in the non-contraction state as compared with isometric contraction and soleus shortening (p < 0.05). A positive correlation of the soleus muscle in the non-contraction state was seen between the maximum power and the λ₁, λ_2, and mean diffusivity. There was a positive correlation between the maximum amount of work and fractional anisotropy in the non-contraction state for the soleus muscle. A negative correlation for the tibialis anterior muscle in the non-contraction state was seen between the maximum amount of work and fractional anisotropy. Overall reproducibility of the DTI parameters was excellent.

DTI parameters were significantly changed depending on the ankle joint position and type of muscle contraction.