Shantanu Sinha PhD, PRESENTER: Nothing to Disclose

Abstract: HTML Purpose: To assess the changes in muscle contraction velocities, muscle volume and strength, using MR based methods, as a means of quantifying muscle function, in patients who have undergone surgery to repair Achilles tendon rupture, and to determine whether these changes normalize after 6 weeks of reambulation and physical therapy (PT). Methods and Materials: 3 subjects who had undergone surgical repair of ATR and subsequent limb immobilization (LI) for 5 weeks, were evaluated, over a period of 6 weeks of PT 3 times/week. Subjects had both legs inserted into a head coil, with the leg to be evaluated immobilized within the posterior half of a leg cast. They exerted periodic isometric contractions, synchronized to a computer generated cue. A fiber optic pressure transducer, imbedded in the sole, measured the force exerted. This was used to measure 100% plantar flexion MVC. The output was also used to gate the MR acquisition, provide a feedback to the subject so that he could maintain consistent timing and levels (50% MVC) of force, and finally for force-strain analysis. Muscle volume was calculated from an axial set of images across the length of the leg, subsequently 3D volume rendered on a Vitrea workstation. Spatial distribution of peak contraction velocity (PCV) within the muscle was evaluated from analysis of velocity encoded, phase contrast imaging of sagittal slices with parameters: TE/TR/FA of 5.3/11.3/30o, a VENC of 10 cm/sec in only the S/I direction, 20 phases/R-R interval. Control MR scans were acquired on the contralateral leg. Results: MG volume decreased by ~26.4% and Sol-DPF by ~11.5%, compared to contralateral limb, after the 5 week of LI. The marked decrease persisted after 6 weeks of PT. Similarly, the Strength Deficit was still present and improved only slightly, with a change of MVC from ~60.2% on day 1 to ~55.3% after 6 wks of PT. PCV of the DPF increased on day 1 and began to normalize on 6 wk recovery. PCV of the MG did not change on day 1 and remained the same as the control leg (+0.28 cm/s) but was altered after 6 wk recovery (-0.03 cm/s). On day 1, the Sol had a PCV of +0.12cm/s which changed in all subjects after PT to +0.32 cm/s. The MG was less affected by the injury than the Sol since it did not have an altered PCV while the Sol did. Both the MG and Sol exhibited changes in PCV after rehab. Conclusion: These data demonstrate the potential that contraction velocity determination and other MR based techniques, may have as a clinical diagnostic tool in the assessment of acute muscle strain injury. These may be more sensitive than conventional torque measurement alone.       Questions about this event email: ssinha@mednet.ucla.edu

Sinha PhD, S, Assessment of Functional Recovery after Surgical Repair of Achilles Tendon Rupture from Estimates of Contraction Velocity, Muscle Volume and MVC ..  Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL. http://archive.rsna.org/2003/3108361.html