Abstract
BackgroundOsteoarthritis (OA) is a serious problem in the recent aging society, and early diagnosis and intervention of articular cartilage degeneration are very important for the onset of OA. Therefore, development of newer MRI techniques is necessary and expected for detection of early articular cartilage degeneration.Methods24 rabbits were randomly divided into four equal experimental groups (Group A, B, C, D) to establish articular cartilage models in different grades of early degeneration by injecting papain into the left knee joint cavity. Another 8 rabbits were considered as blank control (Group E), and then randomized into four subgroups (EA, EB, EC, ED). T1ρ and T2-weighted images of the bilateral knee joints were obtained for rabbits by using 3.0 T MRI. Group A, B, C, and D were imaged respectively at 1, 2, 3, and 4 weeks post-operation, and EA, EB, EC, ED underwent the same period imaging. Rabbits were sacrificed after scanning and the femoral condyle cartilage (FCC) was histological examined. T1ρ values of the femoral condyle cartilage were measured and statistically analyzed, and contrasted with the histologic results.ResultsT1ρ values of the left side in experimental groups were significantly higher than the right side (P < 0.05), and which increased gradually with the passage of post-operation time (P < 0.05). Histological examination demonstrated the proteoglycan content of the left side decreased, and indicated the occurrence of early degeneration.ConclusionsT1ρ MRI can sensitively and quantitatively reflect the change in proteoglycans prior to the morphologic alterations of articular cartilage, and T1ρ value is gradually increased with a decrease in proteoglycan content, therefore that T1ρ could potentially act as a reliable tool to identify early cartilage degeneration.
Highlights
Osteoarthritis (OA) is a serious problem in the recent aging society, and early diagnosis and intervention of articular cartilage degeneration are very important for the onset of OA
For the duration of the imaging session, each rabbit was under general anesthesia with intravenous Ketamine (8 mg/kg) and Midazolam (0.8 mg/kg), and the protocol included 2 sequences: the first, conventional T2-weighted imaging (T2WI) for morphological evaluation were acquired using a fast spin-echo (FSE) imaging on sagittal view, with the following parameters: repetition time/echo time (TR/TE) = 2000 ms/85 ms, slice thickness/spacing = 2 mm/0 mm, field of view (FOV) = 12 × 12 cm, acquisition matrix = 352 × 224, NEX = 2; the second Magnetic resonance imaging (MRI) pulse sequence used for a series of T1ρ-weighted sagittal images was 3D Magnetization-Prepared Angle-Modulated
Histodiagnosis This study performed the injections of papain on rabbits to produce a decline in PG content for setting up the animal models of early articular cartilage degeneration, and the histodiagnosis substantiated the occurrence of biochemical changes in the femoral condyle cartilage (FCC), which with little change in morphology
Summary
Osteoarthritis (OA) is a serious problem in the recent aging society, and early diagnosis and intervention of articular cartilage degeneration are very important for the onset of OA. Osteoarthritis (OA) is the most common joint disorder worldwide, which is the major cause of mobility impaired and disabled in humans [1, 2] It affects approximately 75 % of the population over 70 years of age, while a quarter of people aged over 55 have an episode of persistent knee pain, and there is a rapid increase in the number of the cases due to the aging of the population and the obesity epidemic [2,3,4,5]. The most recent accomplishments have indicated that articular cartilage degeneration is highly likely to play a key role in the pathogenesis of OA, and early diagnosis and intervention of cartilage degeneration before the onset of irreversible changes, are very important for the prevention and treatment of OA [2, 7, 8]. Articular cartilage starts early to degenerate from extracellular matrix (ECM) metabolism imbalance, which mainly involves a gradual loss of proteoglycan (PG), collagen damage and increased water content, and these macromolecular (biochemical) changes are not accompanied by significant structural disturbances in
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