MR T1ρ and T2 of meniscus six months and one year after acute anterior cruciate ligament injury

s / Osteoarthritis and Cartilage 23 (2015) A82eA416 A223 354 MR T1r AND T2 OF MENISCUS SIX MONTHS AND ONE YEAR AFTER ACUTE ANTERIOR CRUCIATE LIGAMENT INJURY A. Wang, F. Su, V. Pedoia, M. Kretzschmar, L. Nardo, T.M. Link, C.B. Ma, X. Li. Univ. of California, San Francisco, San Francisco, CA, USA Purpose: Acute anterior cruciate ligament (ACL) injury, a high-risk factor for post-traumatic osteoarthritis, is often concomitant with meniscal lesions and tears. In our previous cross-sectional study, we found that acute ACL injuries were associated with significantly elevated meniscal T1r and T2 values compared to healthy knees, even in menisci without morphological signs of damage. The goal of this longitudinal study was to evaluate intermediate-term changes in meniscal T1r and T2 quantification in ACL-injured patients six months and one year after ACL reconstruction and to compare these changes to baseline results. Methods: Using a 3T MR scanner, a closed cohort of 39 patients (age 1⁄4 29.4 ± 7.5 years; 16 females) with acute ACL injuries was scanned at an average of 8.4 ± 6.4 weeks post-injury and prior to ACL reconstruction. After ACL reconstruction, follow-up scans of ACL-injured knees were completed at six months and one year after baseline scan. Subjects were categorized by no lateral meniscectomy (n 1⁄4 32) and partial lateral meniscectomy (n 1⁄4 7). Effects of medial meniscectomy were not evaluated due to small sample size (n 1⁄4 2). Imaging protocol included sagittal T2-weighted 3D fast spin-echo (CUBE) images [repetition time (TR)/echo time (TE) 1⁄4 1500/25 ms, field of view (FOV)1⁄4 16 cm, matrix1⁄4 384 x 384, slice thickness1⁄4 1mm, echo train length 1⁄4 50, bandwidth 1⁄4 50 kHz, number of excitations 1⁄4 0.5] and sagittal 3D T1r and T2 quantification sequences [TR/TE 1⁄4 9 ms/min full, FOV1⁄4 14 cm, matrix1⁄4 256 x 128, slice thickness1⁄4 4mm, Views Per Segment 1⁄4 64, time of recovery 1⁄4 1.2 s, spin-lock frequency 1⁄4 500 Hz, ARC phase AF1⁄4 2. TSL1⁄4 0/10/40/80 ms for T1r, and preparation TE1⁄4 0/ 13.7/27.3/54.7 ms for T2]. Menisci were segmented using CUBE images into four sub-compartments: anterior horn of the lateral/medial meniscus (AHLAT/AHMED) and the posterior horn of the lateral/medial meniscus (PHLAT/PHMED). These regions of interest (ROI) were overlaid onto T1r and T2 maps, andmean T1r and T2 values were calculated for each ROI. Paired t-tests were performed when comparing the same cohort at different time points, and unpaired t-tests were performed when comparing patients who had a partial meniscectomy and patients who did not have a meniscectomy. An alpha of less than 0.05 was considered significant. Results: In ACL-injured knees without meniscectomy, T1r values increased significantly from baseline to six months in the AHLAT, AHMED, and PHMED (all p r > -0.46; p r > -0.30; p<0.005). Intraclass correlation coefficients ranged between 0.95-1.00 for the DCE-MRI variables and 0.80-1.00 for the static MRI variables. Conclusions: The results confirm an association between pain and synovitis assessed on both DCEand CE-MRI in obese patients with knee OA. The whole-knee synovitis score on CE-MRI and most of the DCE-MRI variables were also significantly associated with the remaining KOOS items. DCE-MRI analyses were robust and highly reproducible and have the potential to be used to further investigate the role of inflammation and perfusion in knee OA, in a similar way it has been used in inflammatory joint diseases.