An Update on Imaging in Rheumatoid Arthritis

Abstract

Modern imaging modalities allow accurate detection of both inflammation and damage in rheumatoid arthritis (RA) joints. This narrative review aims to summarize the recent literature relating to magnetic resonance imaging (MRI), musculoskeletal ultrasound (MSUS) and high-resolution peripheral quantitative computerized tomography (HR-pQCT). Imaging has aided understanding of the pathogenesis of RA: HR-pQCT studies suggest that cortical micro-channels may facilitate erosive changes in the setting of synovitis. Both MRI and MSUS studies have aimed to quantify the degree of changes seen in asymptomatic people where age-related changes are common, highlighting the importance of understanding the thresholds of ‘normality’. Whilst synovitis has been considered the characteristic feature of RA, there is growing evidence that imaging-detected tenosynovitis may be of importance in predicting the development of RA, diagnosing RA and predicting flare in stable RA. Much focus has been placed on recent MRI and MSUS studies demonstrating that systematic repeated imaging of RA treated with tight control strategies does not improve outcomes at the group level; however these studies did not explore pre-test probability issues at the individual patient level. The literature is somewhat mixed on whether MRI and MSUS may provide useful guidance on which patients in remission can safely have therapy de-escalated. Recent work has also continued to validate and refine pathology definitions and semi-quantitative scoring for these tools as outcome measures in clinical trials. A review of recently published literature allowed the identification of several themes: understanding pathogenesis, attempts to define ‘normal’ joints on imaging, the utility of imaging in the diagnosis of RA, predicting the development of RA in at risk populations and the relevance to Ra clinical practice and trials.