title: Alteration of proton diffusivity associated with passive muscle extension and contraction.
abstract: OBJECTIVE
  To determine whether passive muscle extension and contraction affect the proton diffusivity of the muscle.
  
  
  METHODS
  Five male subjects were examined. The fractional anisotropy (FA), and primary (lambda(1)), secondary (lambda(2)), and tertiary eigenvalues (lambda(3)) of the right tibialis anterior and medial gastrocnemius muscles were compared between conditions of passive plantar flexion and passive dorsiflexion of the ankle joint.
  
  
  RESULTS
  In the tibialis anterior, FA, and lambda(1) at dorsiflexion decreased significantly (P < 0.01 and P < 0.01, respectively) compared to those at plantar flexion, but lambda(3) at dorsiflexion increased significantly (P = 0.02). In the gastrocnemius, FA and lambda(1) at dorsiflexion increased significantly (P < 0.01 and P < 0.01, respectively) compared to those at plantar flexion, but lambda(3) at dorsiflexion decreased significantly (P < 0.01). The lambda(2) value showed no significant change in either the tibialis anterior or medial gastrocnemius.
  
  
  CONCLUSIONS
  The results indicate that passive muscle extension and contraction associated with passive joint movement would affect the proton diffusivity of the muscle. This alteration of proton diffusivity is probably associated with microscopic structural changes of the muscle.
authors.affiliation: Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka City, Japan. mhatake@radiol.meed.kyushu-u.ac.jp
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Hatakenaka
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Matsuo
authors.forename: Taro
authors.initials: T
authors.lastname: Setoguchi
authors.forename: Hidetake
authors.initials: H
authors.lastname: Yabuuchi
authors.forename: Takashi
authors.initials: T
authors.lastname: Okafuji
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kamitani
authors.forename: Kei
authors.initials: K
authors.lastname: Nishikawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Honda
mesh_terms: D000328:Adult; D000843:Ankle Joint / Q000502:physiology; D038524:Diffusion Magnetic Resonance Imaging; D006801:Humans; D007866:Leg; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000502:physiology*; D016059:Range of Motion, Articular