Elastic deformation in tendons and myotendinous tissue: measurement by phase-contrast MR imaging.

Abstract

To determine whether phase-contrast magnetic resonance (MR) imaging can be used to measure stretch in the myotendinous junction and tendon. Velocity-encoded cine MR images obtained during cyclic motion were used to measure strain in myotendinous tissue and indirectly in tendons in gastrocnemius muscle-tendon sutured to a motion phantom. Videotapes of the experiments were digitized and used as a standard of reference for validation of MR measurements. Strain, rotation, and translation of the myotendinous junction were calculated from the phase-contrast MR data and indirectly in the tendon. Strain as determined from the MR imaging experiments agreed with the measurements from the video reference, with linear correlation coefficients of .987 for tendon strain and .992 for strain in the myotendinous junction. Measurement of tendon and myotendinous stretch during movement may provide insight into tendon ability to store energy and a means of noninvasive measurement of muscle force.