AB1350 CAN DIFFUSION-WEIGHTED MRI REPLACE INTRAVENOUS GADOLINIUM CONTRAST-ENHANCED MRI FOR ASSESSMENT OF SYNOVITIS?

Abstract

BackgroundIn clinical trials of rheumatoid arthritis (RA) patients, intravenous gadolinium contrast injection is the gold standard method for MRI assessment of synovitis, e.g. by the OMERACT RA MRI Scoring method (RAMRIS). It has been shown that diffusion-weighted MRI (DW-MRI) allows visualization of synovitis1.ObjectivesTo establish a method for measuring MRI-derived apparent diffusion coefficient (ADC) from DW-MRI and to test its correlation with RAMRIS synovitis scoring.MethodsMRI including diffusion-weighting of the dominant hand was performed in a cohort of RA patients in clinical remission (disease activity score in 28 joints-C-reactive protein [DAS28-CRP] <3.2 and no swollen joints). ADC measurements of the synovium were assessed in 7 areas (3 wrist joint areas and 4 metacarpophalangeal (MCP) joints), similar to the RAMRIS. Intra-observer agreement for the ADC reading was determined using the intraclass correlation coefficient (ICC). Spearman’s rho (ρ) was calculated for the correlation of ADC with RAMRIS Synovitis. Differences in mean ADC between the individual RAMRIS synovitis grades were examined using ANOVA with Bonferroni correction for multiple tests.ResultsIn 63 patients (67% females, age mean 61.0 years (range 36-78 years), disease duration 11.9 years, 0-59 years), DAS28-CRP 2.1 (1.6-3.0) the total RAMRIS synovitis was mean 5.8 (range 0-18). The mean ADC was 0.98x10-3 mm2/s (0.11-2.80). Correlations between RAMRIS synovitis and ADC in the 7 joint areas and mean differences in ADC between RAMRIS synovitis grades are presented in the Table 1. When all 7 joints were pooled the mean ADC and RAMRIS synovitis were moderately positively correlated, ρ=0.49; p<0.01. Statistically significant differences (p<0.01) in mean ADC were observed between all RAMRIS synovitis grades (0 vs 1, 0 vs 2, etc) except for the difference between grade 2 and 3. Good intra-observer (ICC = 0.62 (95%CI 0.49-0.72)) was found.Table 1.All jointsRUJRCJCMCJMCP2MCP3MCP4MCP5RAMRIS synovitis vs ADC correlation, (Spearman’s rho)0.49; p<0.010.39; p<0.010.34; p=0.010.37; p<0.010.59; p<0.010.46; p<0.010.69; p<0.010.42; p<0.01Mean differences in ADC [x10-3 mm2/s]between RAMRIS synovitis grades(ANOVA with Bonferroni correction)0-1-0.20, p<0.01-0.29, p=0.310.09, p=1.00-0.14, p=1.00-0.04, p=1.000.02, p=1.00-0.42, p<0.01n/a0-2-0.55, p<0.01-0.28, p=0.91-0.15, p=1.00-0.27, p=0.43-0.38, p=0.03-0.47, p<0.01-0.62, p<0.01n/a0-3-0.79, p<0.01-0.87, p<0.01-0.20, p=1.00-0.01, p=1.00-0.72, p<0.01-0.57, p<0,01-0.93, p<0.01n/a1-2-0.34, p<0.010.14, p=1.00-0.25, p=0.70-0.13, p=1.00-0.34, p=0.1-0.49, p<0,01-0.19, p=1.00n/a1-3-0.59, p<0.01-0.58, p=0.26-0.29, p=1.000.13, p=1.00-0.68, p<0.01-0.59, p<0.01-0.51, p=0.02n/a2-3-0.24, p=0.09-0.60, p=0.24-0.05, p=1.000.26, p=1.00-0.34, p=0.120.10, p=1.00-0.31, p=0.63n/aIntra-observer ICC (95%CI)0,62 (0,49:0,72)0.70 (0.34:0.89)0.57 (0.14:0.82)0.39 (0.14:0.74)0.81 (0.53:0.93)0.70 (0.34:0.89)(0.81 (0.51:0.93)0.40 (0.18:0.74)ADC: Apparent diffusion coefficient, CI: confidence interval, CMCJ: carpo-metacarpal joint, ICC: intraclass correlation coefficient, MCP: metacarpo-phalangeal joint, RCJ: radio-carpal joint, RUJ: radio-ulnar jointConclusionADC, determined from DWI-MRI, may be used to grade synovitis without the use of gadolinium contrast injection.