Low field dedicated magnetic resonance imaging in untreated rheumatoid arthritis of recent onset

Objective-To compare a low field dedicated extremity magnetic resonance ima ging system (E-MRI) with x ray and clinical examination, in the detection o f inflammation and erosive lesions in wrist and metacarpophalangeal (MCP) j oints in newly diagnosed, untreated rheumatoid arthritis (RA). Patients and methods-Twenty five patients (disease duration less than or eq ual to1 year) and three healthy controls entered the study. An x ray examin ation and MRI (before and after intravenous injection of a contrast agent) of the 2nd-5th MCP joints and the wrist was performed. The number of erosio ns on x ray examination and MRI was calculated, and synovitis in the MCP jo ints and wrists was graded semiquantitatively. Results-E-MRI detected 57 bone erosions, whereas only six erosions were dis closed by x ray examination (ratio 9.5:1). Synovial hypertrophy grades were significantly higher in RA joints with clinical signs of joint inflammatio n-that is, swelling and/or tenderness (median 3, 5th-95th centile 1-4) than without these clinical signs (median 2, 5th-95th centile 1-3), p<0.001. 51 % of the joints without clinical signs Of synovitis showed synovial hypertr ophy on E-MRI. There was a positive correlation between MRI scores of synov itis and the number of erosions detected by MRI in the MCP joints (Spearman r(s)=0.31, p<0.01). No healthy controls had erosions or synovitis on MRI. Conclusion-joint destruction starts very early in RA and E-MRI allows detai led evaluation of inflammatory and destructive changes in wrists and MCP jo ints in patients with incipient RA.