目的 通过磁共振T2定量（T2mapping）成像技术评估3000 m跑步前后膝关节软骨变化,了解膝关节软骨损伤及修复机制,为预防运动训练伤提供影像学依据。方法 选取20名志愿者（40膝）,分别在3000 m跑步前12 h、跑步后6 h、24 h进行膝关节磁共振检查,测量内侧股骨髁软骨中央承重区（CMFC）、外侧股骨髁软骨中央承重区（CLFC）、内侧股骨髁软骨前部非承重区（AMFC）、外侧股骨髁软骨前部非承重区（ALFC）、内侧股骨髁软骨后部非承重区（PMFC）、外侧股骨髁软骨后部非承重区（PLFC）、内侧胫骨软骨（MTC）、外侧胫骨软骨（LTC）各软骨区T2值及软骨厚度;测量内侧半月板前角（AMM）、内侧半月板后角（PMM）、外侧半月板前角（ALM）、外侧半月板后角（PLM）的T2值。采用独立样本t检验比较膝关节软骨T2值,采用单因素方差分析比较各时间点半月板各区域T2值的差异,进一步多组样本均数两两比较采用LSD 法检验。结果 跑步后6 h与跑步前12 h比较,CLFC、CMFC、LTC及MTC的T2值均降低,差异有统计学意义（P<0.05）,AMFC、ALFC的T2值差异无统计学意义;跑步后24 h膝关节各区软骨T2值升高,但与跑步前比较,差异无统计学意义;跑步后6 h与跑步前膝关节软骨厚度差异无统计学意义;跑步后6 h与跑步前比较,PMM、PLM 的T2值降低,差异有统计学意义（P<0.05）;跑步后24 h,软骨T2值基本恢复,但与跑步前12 h比较,差异无统计学意义。结论 磁共振T2mapping成像可以准确评估膝关节软骨在跑步前后的T2值改变,3000m跑步后6 h内股骨及胫骨承重区软骨T2值降低,半月板后角T2值降低,24 h后均基本恢复至跑步前水平。

Objective To evaluate the changes in knee cartilage before and after 3000­meter running using magnetic resonance T2 quantitative (T2mapping) imaging and to understand the mechanisms of knee cartilage injury and repair, providing imaging evidence for the prevention of sports training injuries. Methods A total of 20 volunteers (40 knees) were selected. Knee joint magnetic resonance imaging (MRI) examinations were conducted 12 hours before 3000­meter running, 6 hours after running, and 24 hours after running. T2 values and cartilage thickness were measured in the following cartilage regions: central medial femoral condyle (CMFC), central lateral femoral condyle (CLFC), anterior medial femoral condyle (AMFC), anterior lateral femoral condyle (ALFC), posterior medial femoral condyle (PMFC), posterior lateral femoral condyle (PLFC), medial tibial cartilage (MTC), and lateral tibial cartilage (LTC). T2 values were also measured in the anterior medial meniscus (AMM), posterior medial meniscus (PMM), anterior lateral meniscus (ALM), and posterior lateral meniscus (PLM). Independent t­tests were used to compare T2 values of the knee cartilage regions. One­way analysis of variance (ANOVA) was employed to compare T2 value differences in the meniscus regions across time points, with the Least Significant Difference (LSD) method used for post­hoc pairwise comparisons. Results Compared with 12 hours before running, , T2 values significantly decreased in the CLFC, CMFC, LTC, and MTC, and the differences were statistically significant (P<0.05). No significant differences were found in the T2 values of the AMFC or ALFC. T2 values increased in all knee cartilage regions at 24 hours after running compared to pre­running levels, but these increases were not statistically significant. There was no statistically significant difference in the cartilage T2 values among the knee joint regions at 6 hours after running compared with 12 hours before running. Compared with 12 hours before running, the T2 values of PMM and PLM decreased at 6 hours after running, and the differences were statistically significant(P<0.05). By 24 hours after running, the cartilage T2 values basically recovered, with no statistically significant differences observed compared to the 12­hour pre­running baseline. Conclusions Magnetic resonance T2 mapping imaging can accurately assess changes in T2 values of knee cartilage before and after running. T2 values in the load­bearing cartilage of the femur and tibia decrease at 6 hours following a 3000­meter running, and the T2 values of the posterior horns of the menisci decrease. These values largely return to pre­running levels by 24 hours after running.