title: Assessment of diffusion tensor imaging indices in calf muscles following postural change from standing to supine position.
abstract: OBJECTIVE
  To investigate whether postural change from erect to recumbent position affects calf muscle water diffusivity.
  
  
  METHODS
  Ten healthy adults (27.2 ± 4.9 years, 3 females) were imaged at baseline (following assumption of recumbent position), and after 34 min (session 2) and 64 min (session 3) of laying supine within a 3T MRI scanner. Diffusion tensor imaging (DTI) eigenvalues, fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were evaluated in five calf muscles (anterior and posterior tibialis and triceps surae) during each of the three imaging sessions.
  
  
  RESULTS
  Significant decreases were observed in all of the eigenvalues and ADC in each of the muscles with postural change. These reductions ranged from 3.2 to 6.7% and 3.4 to 7.5% for the various DTI metrics, following 34 and 64 min of supine rest, respectively (P < 0.05). No significant differences were noted in ADC or eigenvalues between the second and third imaging sessions for any muscle. FA did not change significantly with postural manipulation in any muscle compartment.
  
  
  CONCLUSIONS
  Diffusion tensor imaging indices were altered with postural change. As differences were not apparent between the latter two imaging sessions, we suggest that a short supine resting period (~34 min) is sufficient for muscle diffusivity to stabilize prior to quantitative MR imaging in healthy young adults.
authors.affiliation: Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, ON, Canada.
authors.forename: Alyaa H
authors.initials: AH
authors.lastname: Elzibak
authors.forename: Michael D
authors.initials: MD
authors.lastname: Noseworthy
mesh_terms: D000328:Adult; D016880:Anisotropy; D056324:Diffusion Tensor Imaging / Q000295:instrumentation / Q000379:methods*; D004867:Equipment Design; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007866:Leg / Q000033:anatomy & histology*; D008297:Male; D018482:Muscle, Skeletal / Q000033:anatomy & histology*; D016683:Supine Position / Q000502:physiology*