Wheaton Andrew J, Dodge George R, Elliott Dawn M, Nicoll Steven B, Reddy Ravinder
Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Magn Reson Med. 2005 Nov;54(5):1087-93. doi: 10.1002/mrm.20678.
The aim of this study is to develop T1rho as an MR marker of the compositional and functional condition of cartilage. Specifically, we investigate the correlation of changes in cartilage biomechanical and biochemical properties with T1rho relaxation rate in a cytokine-induced model of degeneration. Bovine cartilage explants were cultured with 30 ng/mL of interleukin-1beta to mimic the cartilage degradation of early osteoarthritis. The average rate of T1rho relaxation was calculated from T(1rho) maps acquired on a 4.7 T research scanner. Stress-relaxation biomechanical tests were conducted with a confined compression apparatus to measure uniaxial aggregate modulus (HA) and hydraulic permeability (k0) using linear biphasic theory. Proteoglycan, collagen, and water content were measured via biochemical assays. Average T(1rho) relaxation rate was strongly correlated with proteoglycan content (R2 = 0.926), HA (R2 = 0.828), and log10 k0 (R2 = 0.862). Results of this study demonstrate that T1rho MRI can detect changes in proteoglycan content and biomechanical properties of cartilage in a physiologically relevant model of cartilage degeneration. The T1rho technique can potentially be used to noninvasively and quantitatively assess the biochemical and biomechanical characteristics of articular cartilage in humans during the progression of osteoarthritis.
本研究的目的是开发T1rho作为软骨成分和功能状态的磁共振成像（MR）标志物。具体而言，我们在细胞因子诱导的退变模型中，研究软骨生物力学和生化特性的变化与T1rho弛豫率之间的相关性。将牛软骨外植体与30 ng/mL的白细胞介素-1β一起培养，以模拟早期骨关节炎的软骨降解。T1rho弛豫的平均速率由在4.7 T研究型扫描仪上采集的T(1rho)图计算得出。使用密闭压缩装置进行应力松弛生物力学测试，采用线性双相理论测量单轴聚集模量（HA）和水力渗透率（k0）。通过生化分析测量蛋白聚糖、胶原蛋白和水含量。平均T(1rho)弛豫率与蛋白聚糖含量（R2 = 0.926）、HA（R2 = 0.828）和log10 k0（R2 = 0.862）密切相关。本研究结果表明，T1rho磁共振成像能够在软骨退变的生理相关模型中检测软骨蛋白聚糖含量和生物力学特性的变化。T1rho技术有可能用于在骨关节炎进展过程中对人体关节软骨的生化和生物力学特征进行无创定量评估。
