Subburaj Karupppasamy, Souza Richard B, Wyman Bradley T, Le Graverand-Gastineau Marie-Pierre Hellio, Li Xiaojuan, Link Thomas M, Majumdar Sharmila
Musculoskeletal and Quantitative Imaging Research Group Department of Radiology and Biomedical Imaging, University of California San Francisco, San Francisco, California, USA.
J Magn Reson Imaging. 2015 Feb;41(2):536-43. doi: 10.1002/jmri.24546. Epub 2013 Dec 18.
To prospectively evaluate changes in T1ρ and T2 relaxation times in the meniscal body with acute loading using MRI in osteoarthritic knees and to compare these findings with those of age-matched healthy controls.
Female subjects above 40 years of age with (N1 = 20) and without osteoarthritis (OA) (N2 = 10) were imaged on a 3 Tesla MR scanner using a custom made loading device. MR images were acquired, with the knee flexed at 20°, with and without a compressive load of 50% of the subject's bodyweight. The subjects were categorized based on the radiographic evidence of OA. Three different zones (outer, middle, and inner) of meniscus body were defined (each occupying 1/3rd the width). After adjusting for age and body mass index in the general linear regression model, repeated measures analysis of variance was used to detect significant differences in T1ρ and T2 with and without loading.
In the unloaded condition, the average T1ρ and T2 times were elevated in the outer and middle zones of the medial meniscus in OA subjects compared with the controls. In the loaded condition, T1ρ and T2 times of the outer zone of the medial meniscus was significantly elevated in OA subjects compared with controls. Finally the change (from unloaded to loaded) was significantly higher in controls than OA subjects (15.1% versus 8.3%; P = 0.039 for ΔT1ρ , and 11.5% versus 6.9%, P = 0.049 for ΔT2 ).
These findings suggest that while the OA process appears to affect the relaxation times of all regions within the meniscus, it may affect some regions sooner or to a greater degree. Furthermore, the differences in the change in relaxation times between unloaded and loaded conditions may reveal evidence about load transmission failure of the outer zone of the medial meniscus in subjects with knee OA. It is possible that these metrics (ΔT1ρ and ΔT2 ) may be valuable as an early biomechanical biomarker, which could be used to predict load transmission to the underlying articular cartilage.
采用磁共振成像（MRI）前瞻性评估骨关节炎膝关节半月板体部在急性负荷下T1ρ和T2弛豫时间的变化，并将这些结果与年龄匹配的健康对照者进行比较。
40岁以上患骨关节炎（N1 = 20）和未患骨关节炎（OA）（N2 = 10）的女性受试者，使用定制的加载装置在3特斯拉MR扫描仪上进行成像。在膝关节屈曲20°时，分别在施加和未施加相当于受试者体重50%的压缩负荷的情况下采集MR图像。根据OA的影像学证据对受试者进行分类。定义半月板体部的三个不同区域（外侧、中间和内侧）（每个区域占宽度的1/3）。在一般线性回归模型中对年龄和体重指数进行校正后，采用重复测量方差分析来检测加载和未加载情况下T1ρ和T2的显著差异。
在未加载状态下，与对照组相比，OA受试者内侧半月板外侧和中间区域的平均T1ρ和T2时间升高。在加载状态下，与对照组相比，OA受试者内侧半月板外侧区域的T1ρ和T2时间显著升高。最后，对照组（从未加载到加载）的变化显著高于OA受试者（15.1%对8.3%；ΔT1ρ的P = 0.039，以及11.5%对6.9%，ΔT2的P = 0.049）。
这些结果表明，虽然OA过程似乎会影响半月板内所有区域的弛豫时间，但可能会更快或更严重地影响某些区域。此外，未加载和加载状态下弛豫时间变化的差异可能揭示膝关节OA受试者内侧半月板外侧区域负荷传递失败的证据。这些指标（ΔT1ρ和ΔT2）有可能作为一种早期生物力学生物标志物具有价值，可用于预测向下方关节软骨的负荷传递。
