¹⁸F-FDG PET as a Tool to Predict the Clinical Outcome of Infliximab Treatment of Rheumatoid Arthritis: An Explorative Study

Abstract

18 F-FDG PET is a sensitive, promising method for visualizing disease activity in rheumatoid arthritis. This study aimed to assess the association between changes in 18 F-FDG joint uptake after 2 wk of infliximab treatment and clinical outcome. Methods: Scans were obtained at the initiation of treatment and at 2 wk. Uptake in metacarpophalangeal and wrist joints was quantified using standardized uptake values. Results: Changes in mean standardized uptake value at 0-2 wk significantly correlated with the disease activity score (DAS) at 14 and 22 wk and contributed significantly to the prediction of DAS at these time points. No significant correlation was found between changes in acute-phase reactants at 0-2 wk and the DAS at later time points. Conclusion: Early changes in 18 F-FDG uptake in joints during infliximab treatment of rheumatoid arthritis patients, using PET, may predict clinical outcome. Rheumat oid arthritis (RA) is a disabling joint disease.Stringent monitoring of disease activity and, if necessary, changing to another, more effective, drug treatment has been shown to improve the outcome of patients (1).Anti-tumor necrosis factor (TNF) a-blocking agents, such as infliximab, potently bind TNF and block inflammation by inhibiting the downstream effects of this cytokine. Anti-TNF treatment is effective in reducing disease activity and improving outcome, although not in all patients (2).In general, the response to anti-TNF treatment is assessed between 14 and 22 wk after initiation of the drug. At present, there are no markers that can predict response to anti-TNF treatment at an earlier stage (3-6). Considering the high costs of anti-TNF treatment, that is, $30,500-$38,700 per discounted quality-adjusted life-year gained (7), early prediction of response could reduce the overall costs of treatment.Several reports have shown that inflammation in synovial tissue in RA patients can be detected using 18 F-FDG PET (8-12). Therefore, 18 F-FDG PET may be an interesting tool to assess response early during anti-TNF treatment.This explorative study investigated the potential ability of early 18 F-FDG PET changes to predict clinical outcome at a later stage. MATERIALS AND METHODS Patients and Study ProtocolAll patients (11 women, 5 men) fulfilled the American College of Rheumatology criteria for RA (13). The presence of at least 2 metacarpophalangeal or wrist joints with signs of arthritis was required. Patients were treated with infliximab, and infusions were administered at 0, 2, 6, 14, and 22 wk. At all time points, tenderness and swelling of proximal interphalangeal and metacarpophalangeal joints of hands, elbows, shoulders, and knees (28 joints in total) were determined. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were measured, and the disease activity scores (DASs) of 28 joints were calculated (14). 18 F-FDG PET scans of metacarpophalangeal and wrist joints were acquired at 0 and 2 wk. Informed consent was obtained of all participating patients. The protocol was approved by the local ...

Potential of18F-FDG-PET as a valuable adjunct to clinical and response assessment in rheumatoid arthritis and seronegative spondyloarthropathies

“…The visual assessment of FDG uptake in inflamed joints was not found to be useful as major intraand inter-observer variability was observed. This finding is in contrast to the response assessment performed by Elzinga et al [14] , who studied WB FDG-PET in patients Rest of the whole body survey was unremarkable. Same patient was followed and a response evaluation scan was performed 6 wk after specific treatment for psoriatic arthropathy.…”

“…Our findings are in agreement with those of Kubota et al [7] and Goerres et al [6] who also recommend the use of a FDG uptake scoring system as a useful tool in the assessment of joint inflammation. The difference between the results of Elzinga et al [14] and the other studies could be due to the use of different treatment modalities (biological vs cytoreductive) and duration of the RE scan. However, based on our findings, we recommend the use SUVmax values as quantitative parameters for the assessment of treatment response in RDs.…”

Role of 18F-fluorodeoxyglucose Positron Emission Tomography in the Monitoring of Inflammatory Activity in Crohnʼs Disease

“…The value of these measures in this context has also been demonstrated in other inflammatory disorders such as sarcoidoisis 34 and rheumatoid arthritis 35 . Interestingly, work from the rheumatological literature has gone a step further by demonstrating that early response of SUV within two weeks of treatment initiation can predict clinical response up to 22 weeks into therapy 17,18 . Based on this, and the results presented here we believe that (G)SUVmax and (G)SUVmean should be evaluated as potential markers of clinical response in CD, in preference to systemic or total lesion glycolysis.…”

“…9/13 patients who completed PET scanning both at baseline and a median [range] of 12 [11][12][13][14][15][16][17][18] weeks after initiation of anti-TNF treatment had favourable clinical responses 27 (median [range] responder ΔHBI = 5 [3][4][5][6][7][8][9]; non-responder ΔHBI = 1[-1-2]), (Table 1). …”

“…However, there have been no systematic prospective studies with defined scanning intervals to further investigate this. Several well-designed experiments in appropriate murine models [14][15][16] , as well as human studies in other chronic inflammatory conditions 17,18 have produced encouraging results, but a longitudinal and test-retest reliability data are lacking.…”