FHKAM (Radiology), Department of Diagnostic Radiology, The University of Hong Kong, Hong Kong.
Eur J Radiol. 2013 Apr;82(4):647-50. doi: 10.1016/j.ejrad.2012.11.036. Epub 2013 Jan 17.
Osteoarthritis (OA) of the knee is a common and disabling disease worldwide. Its prevalence is increasing in view of the aging population. Changes in collagen content, its orientation and GAG content in the articular cartilage with age are the major features in knee osteoarthritis. These changes in collagen and GAG contents show no manifestation in plain radiography and conventional magnetic resonance imaging (MRI). Nevertheless, early diagnosis of the knee osteoarthritis is of paramount importance clinically in view of the evolution of putative interventions in its early stage. The aim of this project is to identify the relationships between the two imaging biomarkers (i.e. T1ρ and T2 mappings) and the GAG concentration in living human symptomatic cartilage.
28 patients with clinical diagnosis of knee osteoarthritis were enrolled. 7 males and 16 females were recruited and their mean age was 68.1 (ranges from 53 to 84). Conventional PD sequence, T1ρ and T2 mappings were performed for each subject within 1 week before total knee arthroplasty. Articular cartilage from the lateral tibial plateau was harvested and the GAG content in cartilage was determined by using dimethylmethylene blue method. T1ρ mean and T2 values were calculated and correlate with GAG concentration statistically.
The mean value T1ρ was 40.3±13.5ms, ranging from 15.3 to 69.3ms and the mean value T2 was 31.0±10.5ms, ranging from 16.1 to 46.9ms. The mean value of GAG content was 80.1±33.3mg, ranging from 24.9 to 166.0mg while the mean value of GAG concentration was 267.4±165.9mg/cm(3), ranging from 91.3 to 760.5mg/cm(3). T2 values were inversely correlated with GAG concentration with R(2)=0.375, p=0.001 while T1ρ values were also inversely correlated with GAG concentration with R(2)=0.200, p=0.025.
This in vivo study confirmed that T1ρ and T2 values correlate with the GAG concentration in living human knee cartilages which corroborate with the previous works. The later (T2 values) is found more reliable in our study and less controversial in literatures. We postulate that T2 values can serve as a non-invasive imaging biomarker in the progress of knee osteoarthritis in terms of both disease diagnosis and treatment response monitoring.
膝关节骨关节炎（OA）是一种常见且致残的疾病，在全球范围内普遍存在。鉴于人口老龄化，其患病率正在上升。随着年龄的增长，关节软骨中胶原蛋白含量、取向和 GAG 含量的变化是膝关节骨关节炎的主要特征。这些胶原蛋白和 GAG 含量的变化在普通放射摄影和传统磁共振成像（MRI）中没有表现出来。然而，鉴于早期干预措施的发展，临床上早期诊断膝关节骨关节炎至关重要。本项目的目的是确定两种成像生物标志物（即 T1ρ 和 T2 映射）与活体内膝关节软骨中 GAG 浓度之间的关系。
招募了 28 名临床诊断为膝关节骨关节炎的患者。招募了 7 名男性和 16 名女性，平均年龄为 68.1 岁（范围为 53 至 84 岁）。在全膝关节置换术之前的 1 周内，对每位患者进行常规 PD 序列、T1ρ 和 T2 映射。从外侧胫骨平台采集关节软骨，并用二甲亚甲基蓝法测定软骨中的 GAG 含量。统计计算 T1ρ 均值和 T2 值，并与 GAG 浓度相关。
T1ρ 的平均值为 40.3±13.5ms，范围为 15.3 至 69.3ms，T2 的平均值为 31.0±10.5ms，范围为 16.1 至 46.9ms。GAG 含量的平均值为 80.1±33.3mg，范围为 24.9 至 166.0mg，而 GAG 浓度的平均值为 267.4±165.9mg/cm3，范围为 91.3 至 760.5mg/cm3。T2 值与 GAG 浓度呈负相关，R(2)=0.375，p=0.001，而 T1ρ 值也与 GAG 浓度呈负相关，R(2)=0.200，p=0.025。
这项体内研究证实，T1ρ 和 T2 值与活体内人类膝关节软骨中的 GAG 浓度相关，这与之前的研究结果一致。在我们的研究中，T2 值更为可靠，且在文献中争议较少。我们推测，T2 值可以作为一种非侵入性的成像生物标志物，用于膝关节骨关节炎的疾病诊断和治疗反应监测。
