MRI is considered the standard of reference for advanced imaging in rheumatoid arthritis (RA). However, in daily clinical practice ultrasound (US) imaging with Doppler information is more versatile and often used for fast and dynamic assessment of joint inflammation. The aim was to compare low-field MRI scores with the US Doppler measurements in the wrist joint of patients with RA.
Fifty consecutive patients with RA (46 women & 4 men) completed both low-field dedicated extremity MRI (E-scan®, Esaote) and a high-end US (Sequioa®, Siemens) imaging of the wrist before initiating either biological treatment (n = 26) or intraarticular injection of Depomedrole® (n = 24). Mean age was 56 years (range 21 - 83 years); mean disease duration 87.2 months (range 4 - 349 months), mean DAS 28 4,8 (range 2 - 7). MRI was scored according to the OMERACT RAMRIS recommendations and US Doppler colour-fractions were determined.
Using Spearman's rho, we found a relatively good to moderate correlation between the US colour-fraction and the total OMERACT bone marrow oedema and synovitis scores on MRI (r = 0.6; p < 0.001 and r = 0.4; p < 0.006 respectively). There was a trend but no significant correlation with the total OMERACT erosion score (r = 0.3; p = 0.06).
Within limits, the OMERACT RAMRIS scores of inflammation in RA patients (bone marrow oedema and synovial enhancement) are comparable to the US colour-fraction measurements using a high-end US scanner. Both imaging modalities detect inflammation although showing different aspects of the inflammatory process in the wrist joint. The higher correlation between US colour-fractions and MRI bone marrow oedema indicates a potential importance of US Doppler in monitoring inflammatory disease changes in RA.