title: Muscle changes detected with diffusion-tensor imaging after long-distance running.
abstract: OBJECTIVE
  To develop a protocol for diffusion-tensor imaging (DTI) of the complete upper legs and to demonstrate feasibility of detection of subclinical sports-related muscle changes in athletes after strenuous exercise, which remain undetected by using conventional T2-weighted magnetic resonance (MR) imaging with fat suppression.
  
  
  METHODS
  The research was approved by the institutional ethics committee review board, and the volunteers provided written consent before the study. Five male amateur long-distance runners underwent an MR examination (DTI, T1-weighted MR imaging, and T2-weighted MR imaging with fat suppression) of both upper legs 1 week before, 2 days after, and 3 weeks after they participated in a marathon. The tensor eigenvalues (λ1, λ2, and λ3), the mean diffusivity, and the fractional anisotropy (FA) were derived from the DTI data. Data per muscle from the three time-points were compared by using a two-way mixed-design analysis of variance with a Bonferroni posthoc test.
  
  
  RESULTS
  The DTI protocol allowed imaging of both complete upper legs with adequate signal-to-noise ratio and within a 20-minute imaging time. After the marathon, T2-weighted MR imaging revealed grade 1 muscle strains in nine of the 180 investigated muscles. The three eigenvalues, mean diffusivity, and FA were significantly increased (P < .05) in the biceps femoris muscle 2 days after running. Mean diffusivity and eigenvalues λ1 and λ2 were significantly (P < .05) increased in the semitendinosus and gracilis muscles 2 days after the marathon.
  
  
  CONCLUSIONS
  A feasible method for DTI measurements of the upper legs was developed that fully included frequently injured muscles, such as hamstrings, in one single imaging session. This study also revealed changes in DTI parameters that over time were not revealed by qualitative T2-weighted MR imaging with fat suppression.
authors.affiliation: From the Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands (M.F., G.J.S., K.N.); Department of Radiology, Academic Medical Center, Amsterdam, the Netherlands (M.F., J.O., M.M., A.J.N.); and Department of Human Movement Science, School for Nutrition, Toxicology and Metabolism, Maastricht University, Maastricht, the Netherlands (M.R.D.).
authors.forename: Martijn
authors.initials: M
authors.lastname: Froeling
authors.forename: Jos
authors.initials: J
authors.lastname: Oudeman
authors.forename: Gustav J
authors.initials: GJ
authors.lastname: Strijkers
authors.forename: Mario
authors.initials: M
authors.lastname: Maas
authors.forename: Maarten R
authors.initials: MR
authors.lastname: Drost
authors.forename: Klaas
authors.initials: K
authors.lastname: Nicolay
authors.forename: Aart J
authors.initials: AJ
authors.lastname: Nederveen
mesh_terms: D056324:Diffusion Tensor Imaging; D005240:Feasibility Studies; D006801:Humans; D007866:Leg; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000033:anatomy & histology*; D009929:Organ Size; D012420:Running