Hatcher Courtney C, Collins Amber T, Kim Sophia Y, Michel Lindsey C, Mostertz William C, Ziemian Sophia N, Spritzer Charles E, Guilak Farshid, DeFrate Louis E, McNulty Amy L
Department of Orthopaedic Surgery, Duke University Medical Center, Durham, NC, USA.
Department of Radiology, Duke University Medical Center, Durham, NC, USA.
J Biomech. 2017 Apr 11;55:18-26. doi: 10.1016/j.jbiomech.2017.02.001. Epub 2017 Feb 6.
Non-invasive techniques for quantifying early biochemical and biomechanical changes in articular cartilage may provide a means of more precisely assessing osteoarthritis (OA) progression. The goals of this study were to determine the relationship between T1rho magnetic resonance (MR) imaging relaxation times and changes in cartilage composition, cartilage mechanical properties, and synovial fluid biomarker levels and to demonstrate the application of T1rho imaging to evaluate cartilage composition in human subjects in vivo. Femoral condyles and synovial fluid were harvested from healthy and OA porcine knee joints. Sagittal T1rho relaxation MR images of the condyles were acquired. OA regions of OA joints exhibited an increase in T1rho relaxation times as compared to non-OA regions. Furthermore in these regions, cartilage sGAG content and aggregate modulus decreased, while percent degraded collagen and water content increased. In OA joints, synovial fluid concentrations of sGAG decreased and C2C concentrations increased compared to healthy joints. T1rho relaxation times were negatively correlated with cartilage and synovial fluid sGAG concentrations and aggregate modulus and positively correlated with water content and permeability. Additionally, we demonstrated the application of these in vitro findings to the study of human subjects. Specifically, we demonstrated that walking results in decreased T1rho relaxation times, consistent with water exudation and an increase in proteoglycan concentration with in vivo loading. Together, these findings demonstrate that cartilage MR imaging and synovial fluid biomarkers provide powerful non-invasive tools for characterizing changes in the biochemical and biomechanical environments of the joint.
用于量化关节软骨早期生化和生物力学变化的非侵入性技术，可能提供一种更精确评估骨关节炎（OA）进展的方法。本研究的目的是确定T1rho磁共振（MR）成像弛豫时间与软骨成分变化、软骨力学性能及滑液生物标志物水平之间的关系，并证明T1rho成像在体内评估人体软骨成分中的应用。从健康和患骨关节炎的猪膝关节获取股骨髁和滑液。采集髁的矢状面T1rho弛豫MR图像。与非OA区域相比，OA关节的OA区域T1rho弛豫时间增加。此外，在这些区域，软骨硫酸化糖胺聚糖（sGAG）含量和聚集模量降低，而胶原降解百分比和含水量增加。与健康关节相比，OA关节滑液中sGAG浓度降低，C2C浓度增加。T1rho弛豫时间与软骨和滑液sGAG浓度及聚集模量呈负相关，与含水量和渗透率呈正相关。此外，我们证明了这些体外研究结果在人体研究中的应用。具体而言，我们证明步行会导致T1rho弛豫时间缩短，这与体内负荷时水渗出及蛋白聚糖浓度增加一致。总之，这些发现表明软骨MR成像和滑液生物标志物为表征关节生化和生物力学环境变化提供了强大的非侵入性工具。
