Diffusion tensor imaging assesses triceps surae dysfunction after achilles tenotomy in rats.

PURPOSE

To elucidate the relationship of diffusion tensor imaging (DTI) with structural changes and muscle function in skeletal muscle.

MATERIALS AND METHODS

The subjects were 21 12-week-old male rats. Achilles tenotomy was performed on the right legs. Proton density-weighted images and DTI (7.04T) of the triceps surae at 2 and 4 weeks posttenotomy were obtained. Eigenvalues (λ) and fractional anisotropy (FA) were calculated from the muscle images. After imaging, histological specimens of the triceps surae were prepared. The long axis and cross-sectional area of the triceps surae were measured 2 and 4 weeks postoperatively. The strength of ankle plantar flexion was measured. Correlations of DTI parameters with morphological values and muscle strength were analyzed.

RESULTS

λ1 declined after tenotomy (P < 0.01), and λ2 and λ3 declined at 4 weeks posttenotomy (P < 0.01). FA increased at 4 weeks posttenotomy (P < 0.01). Atrophy of the triceps surae was observed in the tissues images of the treatment group. The muscle belly significantly shortened postoperatively, and a decline in plantar flexion force was observed after tenotomy. Positive correlations were observed between λ1 and muscle strength (r = 0.89) and between λ1 and the length of the long axis of the muscle belly (r = 0.81).

CONCLUSION

DTI may serve as a marker of muscle function.