Background Valid detection of inflamed joints is essential for correct classification, therapeutic decisions and assessment of treatment efficacy in juvenile idiopathic arthritis (JIA).
Objectives Fluorescence optical imaging (FOI) enables visualization of inflammation in arthritis of finger and hand joints and might be used in JIA.
Methods A 24-week observational study in polyarticular JIA patients newly starting treatment with either methotrexate or a biologic was performed. Patients were evaluated clinically, by ultrasound B–mode, power-Doppler and FOI at baseline, week 12 and 24.
Results Of 37 patients enrolled, 24 patients started MTX and 13 a biologic for the first time (Etanercept n=11, Adalimumab and Tocilizumab one 1). Composite measures, mean JADAS 10 decreased significantly from 17.7 at baseline to 12.2 and 7.2 at week 12 and 24 respectively and JIA-ACR 30/50/70/100 response rates at week 24 were 85%/73%/50%/27%. In total 1110 joints were examined clinically, 990 by US/PD and 990 by FOI. At baseline/week12/week24 23.6%/16.4%/9.0% joints on hand and fingers were clinically active joints, by US 19.4%/16.1%/11.5% joints showed effusions, 18.8%/12.7% and 9.6% showed synovial thickening and by PD 6.9%/1.8%/5% joints showed hyperperfusion. Any sign of arthritis was detected by US/PD in 24.5%/19.2%and17%. By FOI at 38.7%/29.2%/27.6% showed a signal enhancement in at least one phase. Summarizing all 3 points of time, the highest numbers of signals were detected by FOI with 32% of joints, especially in phase 2 while by US/PD 20.7% and by clinical examination 17.5% were active. A high number of joints (21.1%) had FOI signals but were clinically inactive. 20.1% of joints with signals in FOI did not show effusion, synovial thickening or hyperperfusion by US/PD. Due to the high number of negative results specificity of FOI compared to clinical examination/US/PD was high (84–95%), sensitivity was moderate only.
Conclusions Improvement upon treatment with either methotrexate or a biologic can be visualized by FOI. FOI and US/PD could detect clinical but also subclinical inflammation. FOI detected subclinical inflammation in higher extent than US.
Disclosure of Interest None declared