Room: AAPM ePoster Library
Purpose: assess the relative sensitivity of T2 and T1? relaxation times to changes in the quadriceps muscles of subjects after an anterior cruciate ligament (ACL) reconstruction. Additionally, to determine the relationship of T2, and T1? to quadriceps muscle strength.
Methods: measured T2 and T1? in the vastus lateralus (VL) quadriceps muscle in the legs of subjects with an ACL injury (n=8) as well as in uninjured controls (n=5). Multi-echo MR images were acquired of the thigh using a Siemens, 3T Trio and a flexible array coil. ROI were drawn by hand around the VL. Quadriceps strength was assessed on an isokinetic dynamometer. A paired t-test was used to evaluate differences between the median of T2 and T1? of the VL in injured and non-injured legs.
Results: For all T1? and T2 measurements the control group was equivalent to the group of uninjured legs. We therefore combined these groups. T1? and T2 measured in the same muscle were highly correlated, (r(25)=0.791, p<0.01). Comparing the VL in injured and non-injured legs, the median T2 and the median T1? were significantly different (5.4%, P<0.05) & (2.7%, P<0.01) respectively. The correlation between muscle force (lower leg torque) normalized by body weight and T1? was weaker, (r(25)=-0.253, p=0.008) than for muscle force and T2 (r(25)=-0.589, p=0.0006).
Conclusion: T2and T1? are sensitive at detecting changes in the VL muscle with injury. Both T2 and T1? are inversely related to normalized lower leg torque with T2 having a slightly stronger correlation than T1?. It is likely that both T2 and T1? reflect levels of edema in the muscle resulting from increased fibrosis following an injury.
Funding Support, Disclosures, and Conflict of Interest: This work was supported by NIH grants UL1TR001998 (P. Kern), K23AR062069 (B. Noehren) and 1S10RR024553 (C. Smith).