Tracking the motion of skeletal muscle with velocity‐encoded MR imaging

Phase‐contrast magnetic resonance velocity‐encoding techniques were used to track two‐dimensional movement of skeletal muscle tissue. Axial and longitudinal planes in the forearms of five healthy volunteers were imaged during cyclic flexion and extension of the fingers, and the resulting data were used to plot the trajectories of the motion of pieces of muscle tissue. A phantom that produced complex two‐dimensional trajectories validated the accuracy of the imaging and analysis techniques; after adjustments for phase errors, two‐dimensional trajectories were tracked with an root‐mean‐square error of 0.1 cm. Preliminary results indicate that velocity‐encoded image data can characterize motion trajectories and that refinements in data acquisition and analysis techniques may make it possible to correlate the movements of different regions within a muscle, characterize muscle contraction, and quantify longitudinal strain. This ability to track velocity vectors may provide a foundation for quantitative analysis of muscle motion.