The use of advanced imaging modalities has allowed greater understanding of the rheumatoid arthritis (RA) disease process and the links between inflammation and damage. The study by Døhn et al1 reported in this issue of the journal (see article on page 252.) is the largest yet published to systematically examine responses to combination anti-tumour necrosis factor (TNF) therapy (adalimumab/methotrexate) in patients naïve to biological agents using MRI, ultrasound (US), plain radiography and high-resolution CT (HRCT) scanning. The inclusion of all four imaging modalities allows important questions to be asked.

First, and most obviously, does anti-TNF therapy/methotrexate prevent the progression of bone erosion? The evidence for this is already very strong from studies using plain radiography to measure outcome,2 and is supported here at a greater level of detail using MRI and US. An earlier publication from the same study provided the same answer using CT scanning.3 There was no overall progression in erosion scores (or MRI erosion volumes) over 12 months, but individuals who were progressors or regressors could be identified and progression or regression of an erosion at individual joints over 12 months could also be studied.

The second question relates to whether changes in MRI and/or US measures of inflammation occur in parallel with changes in clinical disease activity and, by implication, whether these modalities could be used to monitor treatment response. In other words, does the detection of imaging synovitis or osteitis (MRI bone oedema) have any added value over detecting and measuring joint inflammation clinically? In this study, improvements in imaging synovitis (MRI and US) and osteitis (MRI) were concordant with reductions in C reactive protein, functional scores and joint counts, as would be expected. This is consistent with the findings of other studies which have also reported both MRI and US …