Vibration imaging for localization of functional compartments of the extrinsic flexor muscles of the hand

Purpose: To develop and test an MRI-based imaging technique for the localization of the functional compartments of the functionally finger-specific, yet anatomically indistinct, flexor muscles of the hand. Materials and Methods: A total of six normal healthy volunteers were involved in five studies in which individual fingers were vibrated with mechanical actuators and the resultant motion within the corresponding functional compartments of the flexor muscles, mechanically transferred through the structurally connected tendons, was imaged with a phase-contrast MR imaging technique that is highly sensitive to cyclic motion. The motion amplitude and relative phase relationship between the functional compartments of various muscles and fingers were obtained and analyzed from these images as a means to differentiate the various subcompartments. Results: The results show that this technique provides a detailed mapping of the regions of the complex flexor muscle compartments that correspond to each digit for both the flexor digitorum profundus and the flexor digitorum superficialis. The results also demonstrate the presence of mechanical interdependence between the flexor muscles. Conclusion: It is concluded from the results that localization of the finger-specific subcompartments of the forearm flexor muscles can be performed with this technique.