ASSESSMENT OF DISEASE ACTIVITY IN RHEUMATOID ARTHRITIS WITH 18F-FDG PET-CT AND DOUBLE-PHASE BONE SCINTIGRAPHY

Background: 2-(F18)-fluro-2-deoxy-D-glucose Positron Emission Tomography-Computer Tomography (F-FDG/PET-CT) is an innovative technique for the detection of inflammation. 2-(F18)-fluro-2-deoxy-D-glucose (F-FDG) is taken up by leucocytes, fibroblasts and macrophages in experimental models of arthritis. Bone scintigraphy, and especially double phase bone scintigraphy is an important tool for staging and follow-up in patients with rheumatoid arthritis. While bone scintigraphy already was evaluated for the detection of synovitis in rheumatoid arthritis (RA), F-FDG/PET-CT may be a novel and more sensitive tool.Objectives: The aim of this study was to asses synovitis in an individual joint analysis and to compare F-FDG/PET-CT with double-phase bone scintigraphy and clinical parameters of RA.Methods: Wrists, carpometacarpal, metacarpophalangeal and proximal interphalangeal joints were studied in twelve patients with clinically active RA. Independent investigators performed clinical examinations (28 joint count and disease activity score(DAS)), as well as F-FDG/PET-CT and double-phase bone scintigraphy examinations of the hands. F-FDG/PET-CT and bone scintigraphy analyses consisted of a visual identification of F-FDG uptake in the joints. Statistical correlation of F-FDG/PET-CT, bone scintigraphy and the joint count was calculated using Cohen''s Kappa.Results: A total of 312 joints were studied, in twelve patients with a mean DAS of 3.8 (±1.3) F-FDG/PET-CT positivity was found in 30% (n=95) of the analysed joints, whereas 31% (n=96) showed swelling in the 28 joint count and 27% (n=84) were positive in the double-phase bone scintigraphy. In a global analyses of F-FDG/PET-CT and double-phase bone scintigraphy, positive joints were significantly correlated with swollen joint count (p<0.0001). There was also a good statistical correlation (p<0.0001) in the direct comparison of F-FDG/PET-CT and double-phase bone scintigraphy.Conclusion: F-FDG/PET-CT is a new imaging technique that can asses synovitis and shows a good correlation with clinical parameters of RA. The results of F-FDG/PET-CT in patients with clinically active RA are well correlated with the clinical methods for assessment of disease activity as well as with double-phase bone scintigraphy.References: 1. Zhuang H, Alavi A;18-fluorodeoxyglucose positron emission tomographic imaging in the detection and monitoring of infection and inflammation. Semin Nucl Med. 2002; 32(1):47-59.2. Cornelius P, Marlowe M, Pekala PH. Regulation of glucose transport by tumor necrosis factor-alpha in cultured murine 3T3-L1 fibroblasts. J Trauma. 1990; 30(12 Suppl):S15-20.3. Gamelli RL, Liu H, He LK, Hofmann CA. Augmentations of glucose uptake and glucose transporter-1 in macrophages following thermal injury and sepsis in mice. J Leukoc Biol. 1996; 59(5):639-47.Citation: Ann Rheum Dis, volume 64, supplement III, year 2005, page 211Session: Rheumatoid arthritis – Clinical aspects