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

Abstract

Objective: To compare a low field dedicated extremity magnetic resonance imaging system (E-MRI) with x ray and clinical examination, in the detection of inflammation and erosive lesions in wrist and metacarpophalangeal (MCP) joints in newly diagnosed, untreated rheumatoid arthritis (RA).

Patients and methods: Twenty five patients (disease duration < or =1 year) and three healthy controls entered the study. An x ray examination 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 erosions on x ray examination and MRI was calculated, and synovitis in the MCP joints and wrists was graded semiquantitatively.

Results: E-MRI detected 57 bone erosions, whereas only six erosions were disclosed by x ray examination (ratio 9.5:1). Synovial hypertrophy grades were significantly higher in RA joints with clinical signs of joint inflammation-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 hypertrophy on E-MRI. There was a positive correlation between MRI scores of synovitis 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 detailed evaluation of inflammatory and destructive changes in wrists and MCP joints in patients with incipient RA.

Figure 1

(A) Patient positioning for extremity magnetic resonance imaging. (B) Hand with extended fingers placed in the coil. To avoid movements the hand was fixed by foam rubber pillows.

Figure 2

Healthy control. Magnetic resonance images of wrist and metacarpophalangeal (MCP) joints. No synovitis or erosions. (A-C) Coronal STIR-image (A) and coronal T₁ weighted spin echo images before (B) and after (C) IV gadodiamide. (D, E) Transversal T₁ weighted spin echo images of the MCP joints before (D) and after (E) IV gadodiamide. No intra-articular areas with high signal intensity (bright) on STIR or after IV contrast are seen. Thus no signs of synovitis are found.

Figure 3

Patient with rheumatoid arthritis. Magnetic resonance images of wrist and metacarpophalangeal (MCP) joints show synovitis in the wrist joint and tenosynovitis. (A-C) Coronal STIR image (A) and coronal T₁ weighted spin echo images before (B) and after (C) IV gadodiamide. (D, E) Transversal T₁ weighted spin echo images of the wrist before (D) and after (E) IV gadodiamide. In the wrist joint, areas with high signal intensity (bright) on STIR and after IV contrast are seen corresponding to the synovium (grade 4—that is, synovitis, straight arrows) as well as around the flexor tendons (tenosynovitis, curved arrows). No signs of synovitis are seen in the 2nd-5th MCP joints.

Figure 4

Patient with rheumatoid arthritis. Magnetic resonance images and x ray picture of the wrist and metacarpophalangeal (MCP) joints show synovitis and bone erosion in the 2nd MCP joint. (A-C) Coronal STIR image (A) and coronal T₁ weighted spin echo images before (B) and after (C) IV gadodiamide. (D, E) Transversal T₁ weighted spin echo images before (D) and after (E) IV gadodiamide. In the 2nd MCP joint, areas with high signal intensity (bright) on STIR and after IV contrast are seen corresponding to the synovium (grade 4—that is, synovitis, large white arrows) as well as in the bone (bone erosion, small black arrow). No signs of synovitis are seen in the 3rd-5th MCP joints. Mild, grade 2 synovial membrane hypertrophy was found in the wrist, but is not properly visualised in the presented slice. (F) Conventional x ray in the anteroposterior projection. The erosion in the 2nd metacarpal head is not seen.