title: Diffusion tensor imaging assesses triceps surae dysfunction after achilles tenotomy in rats.
abstract: OBJECTIVE
  To elucidate the relationship of diffusion tensor imaging (DTI) with structural changes and muscle function in skeletal muscle.
  
  
  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).
  
  
  CONCLUSIONS
  DTI may serve as a marker of muscle function.
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Hara
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Ikoma
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Kido
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Sukenari
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Arai
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Hiroyoshi
authors.initials: H
authors.lastname: Fujiwara
authors.affiliation: Department of Anatomy and Neurobiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Kawata
authors.affiliation: Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Kubo
mesh_terms: D000125:Achilles Tendon / Q000601:surgery*; D000818:Animals; D016880:Anisotropy; D056324:Diffusion Tensor Imaging; D006614:Hindlimb / Q000503:physiopathology; D008297:Male; D018482:Muscle, Skeletal / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D058971:Tenotomy
keywords: Achilles tendon; DTI; MRI; muscle function