Page 101 - Imaging of Osteoarthritis and Rheumatoid Arthritis in Hand Joints

Accuracy of low field MRI in early arthritis
Introduction
Magnetic Resonance Imaging (MRI) is a valuable tool in the detection of patients with peripheral inflammatory joint diseases. It is more sensitive than radiography for detecting bone erosions,1-3 it is very sensitive in the detection of synovitis,4-7 and it is the only imaging technique which can detect bone marrow oedema (BME), which is often seen in inflammatory joint disease and is a predictor of progression of Rheumatoid Arthritis (RA).8-10
A variety of MRI hardware is used to detect these pathologies associated with inflammatory arthritis. Used magnetic field strengths vary from 0.2 to 3 Tesla (T); with 1.5T MRI currently being the most widely available. Higher field strength MRI scanners provide a better image quality, but low field extremity MRI scanners are less expensive and more comfortable for patients.11, 12 Previous studies have shown that low field MRI, despite its lower image quality, is equally effective as high field MRI in the detection of synovitis and erosions in patients with established RA, but low field MRI seemed less accurate in the detection of bone marrow oedema and tenosynovitis as high field MRI.13, 14
Ultrasound is another imaging method to detect synovitis and is more affordable
and better available than both MRI techniques. While ultrasound seems not 6 as good as MRI to detect erosions 15, and cannot detect BME, ultrasound with
power Doppler seems as good as low field and high field MRI to detect active
synovitis in hand and MTP joints in patients with diagnosed RA 16, 17
Most imaging studies have been performed on patients with diagnosed RA. However, patients with early inflammatory unclassified arthritis or arthralgia who may be at risk for developing RA or other inflammatory arthritis could benefit from early detection of inflammatory arthritis with MRI or ultrasound. Earlier detection of joint disease means earlier treatment, and possible prevention of permanent joint damage. For patients with arthralgia it is unknown how accurate low field MRI is in comparison with high field MRI and ultrasound.
We therefore investigated the utility of 0.2T extremity MRI for detecting synovitis, bone erosions, and bone marrow oedema in patients presenting
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