Abstract
Purpose
To determine whether passive muscle extension and contraction affect the proton diffusivity of the muscle.
Materials and Methods
Five male subjects were examined. The fractional anisotropy (FA), and primary (λ~1~), secondary (λ~2~), and tertiary eigenvalues (λ~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 λ~1~ at dorsiflexion decreased significantly (P < 0.01 and P < 0.01, respectively) compared to those at plantar flexion, but λ~3~ at dorsiflexion increased significantly (P = 0.02). In the gastrocnemius, FA and λ~1~ at dorsiflexion increased significantly (P < 0.01 and P < 0.01, respectively) compared to those at plantar flexion, but λ~3~ at dorsiflexion decreased significantly (P < 0.01). The λ~2~ value showed no significant change in either the tibialis anterior or medial gastrocnemius.
Conclusion
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. J. Magn. Reson. Imaging 2008;27:932–937. © 2008 Wiley‐Liss, Inc.