Purpose: Comparison of dedicated low-field magnetic resonance imaging (lfMRI) and conventional magnetic resonance imaging (cMRI) in the detection and scoring of synovitis, tenosynovitis, and erosions in patients with rheumatoid arthritis (RA).
Materials/Methods The wrist and finger joints of 17 patients with RA (median disease duration 8 years [7;12]; Disease Activity Score 3.3 [2.6;4.5]) were examined by 0.2 Tesla lfMRI and 1.5 Tesla cMRI. The protocols comprised coronal spin-echo and 3D gradient echo sequences before and after contrast medium administration. Synovitis of the metacarpophalangeal and proximal interphalangeal joints 2 – 5 and the wrist joints was scored according to Outcome Measures in Rheumatology (OMERACT) recommendations. Tenosynovitis and erosions were scored using 4 point and 6 point scales, respectively. The results were analyzed by calculating kappa values and performing McNemar’s test intra-individually on a joint-by-joint basis.
Results: Agreement between the two MRI techniques was good to excellent for synovitis and erosions, and moderate for tenosynovitis. Of the 306 joints evaluated, 245 and 200 joints showed synovitis in lfMRI and cMRI, respectively. Scoring of synovitis of the finger joints yielded kappa values from 0.69 to 0.94. Of the 68 flexor tendons evaluated, tenosynovitis was diagnosed by lfMRI in 24 and by cMRI in 33 instances. Of the 391 bones evaluated, 154 and 139 showed erosions in lfMRI and cMRI, respectively. Kappa values for erosion scores were between 0.65 and 1.0.
Conclusion: Dedicated, low-field MRI shows high agreement with conventional MRI in diagnosing and scoring synovitis, tenosynovitis, and erosions in RA when using standardized scoring systems.
- Magnetic resonance imaging
- low-field MRI
- rheumatoid arthritis