Objective. To determine the magnetic resonance imaging (MRI), macroscopic, and microscopic characteristics of synovial membrane inflammation, to study the relationship between disease severity and the degree of synovial inflammation on MRI and on macroscopic and microscopic examination, and to look for colocalization of chondral lesions and synovial inflammation.Methods. Thirty-nine patients with knee osteoarthritis (OA) were classified into 2 groups according to the severity of cartilage lesions as revealed by chondroscopy. Group 1 (n ‫؍‬ 14) had mild cartilage lesion(s) without exposure of subchondral bone. Group 2 (n ‫؍‬ 25) had severe cartilage lesion(s) with focal or diffuse exposure of subchondral bone. Synovitis was evaluated on T1-weighted MRI sequences according to the degree of synovial thickening on a 4-point scale (ranging from 0 to 3) in 5 regions of interest. Synovial membrane was macroscopically scored, and biopsies were performed on the 5 preselected sites for histologic scoring.Results. The mean ؎ SD synovial thickening score on MRI was 1.55 ؎ 0.90, with no significant difference between groups 1 and 2. Intra-and interobserver reproducibility of the total synovial score was excellent, and interobserver reproducibility of the MRI grade was good. Conclusion. Synovitis may be present from the onset of OA and may be evaluated on MRI. MRI evaluation of synovitis could be used to classify OA patients in clinical trials and could help to identify those who could benefit from synovium-targeted therapy.Osteoarthritis (OA) is the most prevalent form of arthritis and a major cause of disability worldwide (1).

Objectives: : To study synovial membrane (SM) inflammation near the patella with different magnetic resonance imaging (MRI) approaches performed using a T1-injected sequence in knee osteoarthritis (OA), and to compare MRI results with macroscopic, microscopic and clinical findings.Methods: Fifteen patients fulfilling American College of Rheumatology (ACR) criteria for knee OA and requiring joint lavage completed a functional index (Lequesne's functional index) and a pain visual analog scale (VAS). SM inflammation near the patella was assessed on axial fat saturation post-injected T1 MRI images using three different methods: (1) semi-quantitative score ¼ MRI synovitis score; (2) synovial membrane volume (SMV) analysis; (3) SMV with low (SMVL) (<0.3%/s À1 ), intermediate (SMVI) (0.3%/s À1 to 1%/s À1 ) and high (SMVH) (!1%/s À1 ) speed of enhancement. Chondral lesions and SM inflammation were macroscopically graded and SM biopsies performed for microscopic scoring.Results: All MRI approaches exhibited excellent intra-and inter-observer reproducibility. MRI synovitis score correlated well with macroscopic (r ¼ 0.61, P ¼ 0.003) and total microscopic scores (r ¼ 0.55, P ¼ 0.03). Correlations between SMV and macroscopic (r ¼ 0.60, P ¼ 0.02) and microscopic congestion (r ¼ 0.63, P ¼ 0.01) were good. SMVH was correlated only with microscopic congestion (r ¼ 0.79, P ¼ 0.01). Low SMV was associated with neither macroscopic nor microscopic scores. However, it did correlate well with pain-VAS score (r ¼ 0.61, P ¼ 0.03) and moderately with a functional index (r ¼ 0.46, P ¼ 0.10). Conclusion:The three MRI approaches used here provided highly reproducible information on SM inflammation near the patella in knee OA. Compared to SMV, MRI synovitis score seems sufficient to assess synovial inflammation but high SMV is an appropriate indicator of vascular congestion, and low SMV reflects pain in knee OA.

AimThe aim of this work was the development of successful cell therapy techniques for cartilage engineering. This will depend on the ability to monitor non-invasively transplanted cells, especially mesenchymal stem cells (MSCs) that are promising candidates to regenerate damaged tissues.MethodsMSCs were labeled with superparamagnetic iron oxide particles (SPIO). We examined the effects of long-term labeling, possible toxicological consequences and the possible influence of progressive concentrations of SPIO on chondrogenic differentiation capacity.ResultsNo influence of various SPIO concentrations was noted on human bone marow MSC viability or proliferation. We demonstrated long-term (4 weeks) in vitro retention of SPIO by human bone marrow MSCs seeded in collagenic sponges under TGF-β1 chondrogenic conditions, detectable by Magnetic Resonance Imaging (MRI) and histology. Chondrogenic differentiation was demonstrated by molecular and histological analysis of labeled and unlabeled cells. Chondrogenic gene expression (COL2A2, ACAN, SOX9, COL10, COMP) was significantly altered in a dose-dependent manner in labeled cells, as were GAG and type II collagen staining. As expected, SPIO induced a dramatic decrease of MRI T2 values of sponges at 7T and 3T, even at low concentrations.ConclusionsThis study clearly demonstrates (1) long-term in vitro MSC traceability using SPIO and MRI and (2) a deleterious dose-dependence of SPIO on TGF-β1 driven chondrogenesis in collagen sponges. Low concentrations (12.5–25 µg Fe/mL) seem the best compromise to optimize both chondrogenesis and MRI labeling.