骨关节炎(OA)是以进行性关节软骨退变为特征的常见关节疾病，目前仍缺乏早期诊断方法，常规影像学手段诊断OA时多已不可逆，只能关节置换。研究表明最新MRI技术UTE T2* mapping（U）和gagCEST（g）能评估关节软骨质量，课题组前期实验发现U可准确定量正常关节软骨化学成分，所得长、短T2*相关参数分别代表组织内水成分（长）和胶原纤维、糖胺聚糖（短）含量。基于这一发现，申请者提出假说：联合U和g定量软骨化学成分可能会为早期OA的诊断提供可靠影像学手段。课题组拟联合U和g技术定量不同等级离体OA关节软骨成分，分析其诊断不同等级OA可行性。然后制作OA动物模型，使用U和g动态监测OA动态时序变化过程，以分子生物学分析、组织学染色和PLM结果为标准，验证U和g诊断早期OA的可行性。为临床早期OA的诊断和疗效评估提供准确手段，将对实现OA早发现早治疗、改善OA患者生活质量有重大意义。

Osteoarthritis (OA) is a common joint disease characterized by progressive degeneration of articular cartilage. Conventional imaging methods used to diagnosis OA by evaluating the morphological integrity of the articular cartilage, however the OA are already at late stage and irreversible when the loss of articular cartilage were diagnosed. There is no effective treatment method except total knee arthroplasty. Studies have shown that the latest MR technology UTE T2 * mapping (U) and gagCEST (g) can evaluate the articular cartilage. Preliminary results of the applicants’ group found that U can accurately quantify the composition of normal articular cartilage, the long and short T2* relaxation time and their relative fraction represent the quantity and quality of tissue water (long) and collagen fibers(short), glycosaminoglycan (short) content separately. Based on these findings, we hypothesize that combining U and g technique on evaluating articular cartilage may provide a precise imaging modality for diagnosing early OA. First, we will evaluate different grades of OA articular cartilage with U and g to determine the feasibility of using U and g of diagnosing different levels of OA. Then the animal models of OA will be made, and the longitudinal changes of OA cartilage will be monitored by U and g. Thus, the feasibility of U and G in diagnosing early OA will be verified, and realtime-PCR, Western Blot analysis, histological staining and PLM results will be set as reference. It is of great significance to provide an imaging means to diagnosis early OA and monitor the therapeutic efficacy, and furthermore the treatment of early OA will improve the quality of life of patients with OA.