To identify the magnetic resonance imaging (MRI) parameter that best differentiates healthy persons and patients with early rheumatoid arthritis (RA), and to investigated responsiveness to treatment of various MRI parameters.
Conventional MRI and dynamic contrast-enhanced (DCE)-MRI of the hand were performed once for 26 healthy persons, and before and after 6 and 12 months of disease-modifying anti-rheumatic drug (DMARD) treatment for 14 early RA patients, using a 1.0-T MRI unit. One-slice DCE-MRI was analysed using Dynamika version 4.2. The number of enhancing voxels (Nvoxel), the initial rate of enhancement (IRE), the maximum enhancement (ME), ME×Nvoxel, and IRE×Nvoxel were calculated for wrist and 2nd-5th metacarpophalangeal (MCP) joints. Conventional MR images were evaluated using the RA MRI scoring system (RAMRIS) synovitis score.
Using DCE-MRI, enhancement was demonstrated in 61.5% of healthy persons and in 91.7% of RA patients at baseline, with a median Nvoxel of 3 and 362, respectively. At baseline, all parameters were higher for patients than for healthy persons (all p ≤ 0.003). Only one patient had a baseline RAMRIS synovitis score below the 95th percentile of the healthy persons. The corresponding number of patients was 3 for Nvoxel, ME×Nvoxel and IRE×Nvoxel, and 10 for IRE and ME. The RAMRIS synovitis score and IRE showed the highest responsiveness, with a standardized response mean (SRM) of -1.00 and -0.88, respectively.
The RAMRIS synovitis scoring of conventional MRI, and to a lesser extent the one-slice DCE-MRI parameters of synovial volume, differentiated early RA patients and healthy persons. The decrease in RAMRIS synovitis score, Nvoxel, and IRE showed sensitivity to change during treatment.