Arthritis and vascular inflammation made visible

Rheumatoid arthritis (RA) is a chronic systemic inflammatory disease. RA primarily affects the joints and surrounding tissues, where chronic inflammation leads to progressive destruction of bone and cartilage and causing severe pain and disability. Characteristic for RA is inflammation of the synovial tissue in multiple joints, mainly symmetrically in small hand and foot joints. It is known that RA patients have an increased risk of cardiovascular disease (CVD) compared to the general population. The optimal management of RA requires objective tools that allow early diagnosis, prediction of treatment response and monitoring of therapeutic interventions. Imaging methods offer the opportunity to objectively measure inflammation and disease activity. In addition, imaging methods may be used to improve our knowledge on the pathophysiology of RA and its comorbidities. In this thesis the value of new imaging methods for clinical practice in RA was explored, focusing on prediction of RA development and therapy monitoring. Identifying individuals with high risk of RA offers the opportunity to develop strategies for prevention of RA in these individuals. This thesis points out that imaging in at-risk individuals might be especially of added value in those individuals where the risk of developing arthritis is unclear. Monitoring disease progression during treatment is important to actively steer towards remission or low disease activity, and to be able to intervene early when disease activity increases. In this thesis optical spectral transmission (OST) was investigated as a new imaging method for the detection of disease activity in RA. The results show that there is little value for OST for the prediction of arthritis, but it may have value for therapy monitoring in the future. Nonetheless, OST needs optimalization of the prediction algorithm before we keep continuing doing scientific research with the current device. In the second part of this thesis, imaging methods were used to investigate vascular biomarkers to improve our knowledge on cardiovascular comorbidity. It is hypothesized that the increased CVD risk in RA is a result of arterial wall inflammation induced by the chronic inflammatory process inherent to RA, and in this thesis arterial wall inflammation was visualized and quantified using imaging techniques to investigate this hypothesis. The results show that with 18F-FDG-PET/CT imaging it is possible to investigate not only the effect of anti-inflammatory treatment on joint inflammation, but also on systemic inflammation in the arterial wall. This offers the opportunity for future studies to investigate whether treatment (in a treat-to-target setting) should be steered on the joints alone, or possibly also on the vessels.