Page 112 - Imaging of Osteoarthritis and Rheumatoid Arthritis in Hand Joints

Chapter 6
Discussion
Contrast enhanced 0.2T MRI in patients with early arthritis or inflammatory hand arthralgia showed good agreement with 1.5T MRI for detection of synovitis, moderate agreement for detection of erosions and poor agreement for detection of BME. Ultrasound showed poor agreement with both 1.5T and 0.2T MRI for detection of synovitis and erosions. These results suggest that contrast enhanced 0.2T MRI is a good method for synovitis detection, better that ultrasound.
Our MRI synovitis results are in line with studies performed in cohorts of RA patients, in which there was an overall good agreement between low and high field MRI of κ 0.69-0.94, and ICC 0.40-0.96,13, 14, 29. The standardized US examination evaluating the joints in specific fixed imaging planes detected less joints with synovitis and identified less patients with synovitis compared to the US examination of the joint without fixed planes, and MRI. However, if synovitis was detected with standardized US, it was almost always also present on MRI. These ultrasound findings are in line with a recent systematic review in RA patients. This review identified 12 studies on US detection of synovitis in hand and wrist with MRI used as the reference standard 30. The included US studies showed variable amounts of sensitivity, variable amounts of specificity in the wrist, and high specificity in almost all MCP and PIP studies. No information about scanning protocol or probe positions was further specified in this review, which may explain the large variation in results. The clinical US method without fixed planes detected more joints with synovitis than standardized US, but this method also had a low agreement with synovitis on MRI. Previously, it has also been shown that US without fixed planes give varying results in research,31, 32 and this method therefore seems suboptimal. The lower sensitivity of fixed plane ultrasound in detection of synovitis may be explained due to the fact that there is often asymmetric or focal synovial thickening which may be only visible outside the standardized planes.
There was moderate agreement for erosions detection between 0.2T extremity MRI and 1.5T MRI. The agreement we found was lower than similar studies with diagnosed RA patients where high agreement was found in all wrist and MCP bones: κ 0.65-1,14 ICC 0.76-0.99,29 and ICC 0.94.13 A possible explanation
110