SCINTIGRAPHIC EVALUATION OF THE SEVERITY OF INFLAMMATION OF THE JOINTS WITH TC-99(M)-HIG IN RHEUMATOID-ARTHRITIS

A prospective study was carried out to determine the usefulness of Tc- 99(m)-human immunoglobulin G (HIG) scintigraphy in the assessment of t he severity of joint inflammation. Twenty-four patients with rheumatoi d arthritis were studied. The presence or absence of pain and/or swell ing was evaluated in 34 joints and a clinical index taking into accoun t the surface area of each joint was calculated. We measured the follo wing biological markers of inflammation activity: erythrocyte sediment ation rate, C-reactive protein, haemoglobin, platelet count, serum lev els of IL-6, TNF-alpha and soluble receptors of IL-2. Scintigraphy was performed 4 h after the injection of 740 MBq Tc-99(m)-HIG. The scans were evaluated by visual and quantitative analysis and the scores in e ach joint were weighted for joint size. Pathological uptake of the rad iopharmaceutical was noted in 46% (24/52) of joints evaluated as painf ul, 89% (146/164) of swollen joints and 94% (78/83) of both painful an d swollen joints. Both the visual and the quantitative scintigraphic i ndices correlated significantly with the clinical index, the number of painful joints, the number of swollen joints and several biological m arkers of inflammation. A very high correlation was also found between the visual and the quantitative scintigraphic indices (r = 0.91, P < 0.0001). In conclusion, Tc-99(m)-HIG scintigraphy is an objective test to detect synovitis and to assess the severity of inflammation. A car eful visual analysis of scans is good enough for routine evaluations a nd computer quantitative analysis should be used when more accurate in tra-individual variation is required.