Low-field MRI versus ultrasound: which is more sensitive in detecting inflammation and bone damage in MCP and MTP joints in mild or moderate rheumatoid arthritis?

OBJECTIVES

The aim of the present paper is to determine if the ultrasound of hands and feet is comparable to the MRI of the dominant hand to detect erosive disease and inflammation in mild or moderate rheumatoid arthritis (RA).

METHODS

Twenty-six patients (14 females; mean age, 48 years) with active mild or moderate RA (mean DAS28, 3.9; mean disease duration, 19 months) were examined clinically, by ultrasound and by gadolinium-enhanced low-field MRI at baseline, after 6 and 12 months (78 examinations). Radiographs from hands and forefeet were taken at baseline and after 12 months. MRI was performed at the clinically most active (dominant) hand or forefoot evaluating the MCP 1-5 or MTP 1-5 joints. Ultrasound examination additionally included all other 2nd, 5th MCP and 5th MTP joints.

RESULTS

MRI and ultrasound detected erosive disease in 67 and 56 of 78 examinations, respectively (p<0.01); radiography only in 8 of 52 examinations (p<0.001). MRI and ultrasound were equally sensitive to detect synovitis (in 64 and 66 examinations). Synovial power Doppler signals were present in 38 ultrasound examinations. Bone marrow oedema was present in 37 MRI examinations. Ultrasound was more sensitive than MRI to detect tenosynovitis (in 30 vs. 15 examinations; p=0.001).

CONCLUSIONS

MRI of the dominant hand and bilateral ultrasound of MCP and MTP joints are superior to x-ray to detect erosive disease in mild and moderate RA. MRI is slightly, but significantly more sensitive than ultrasound for erosive disease, while ultrasound is more sensitive to detect tenosynovitis. Ultrasound and MRI are comparably sensitive to detect synovitis.