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Purpose: To evaluate a novel quantitative methodology to assess inflammatory changes in magnetic resonance imaging (MRI) data from patients with rheumatoid arthritis (RA) and the impact of image quality on imaging outcomes compared to the RA Magnetic Resonance Imaging Score (RAMRIS). Methods: Three-dimensional, T1-weighted, fat-suppressed MRI sequences of the hand/wrist before and after intravenous Gadolinium contrast from patients with RA in a placebo-controlled clinical trial (NCT01185353) were re-evaluated post hoc. The methodology was integrated into proprietary software (DYNAMIKA®) and assessed inflammation through pixelated measurements of the contrast-enhancing (inflammatory) volume. A semi-automatic approach outlined contrast-enhancing synovial tissue in the wrist and second to fifth metacarpophalangeal joints with a rough region of interest (ROI); quantitative imaging biomarkers were generated by means of quantitative total volume of inflammation and quantitative degree of inflammation relative to the signal in a 1 cm in diameter ROI in the center of the thenar or lumbrical muscle for internal reference. The time from Gadolinium injection to finalization of the post-contrast images was calculated from the images’ Digital Imaging and Communications in Medicine header. An experienced reader graded image quality as poor, acceptable, or good. Results: Results from this quantitative methodology, especially when excluding images with poor quality scores (14–32%), provided a more pronounced and monotonically increasing dose-response than the original RAMRIS results on synovitis and osteitis. Conclusions: This computer-aided quantitative scoring method provided continuous measures of inflammatory changes relative to muscle and may be more sensitive and interpretable concerning dose/response separation between RA treatment groups.

In this commentary, we discuss the potential of advanced imaging, particularly Dynamic Contrast Enhanced (DCE) magnetic resonance imaging (MRI) for the objective assessment of the inflammatory process in rheumatoid arthritis (RA). We emphasise the potential of DCE-MRI in advancing the field and exploring new areas of research and development in RA. We hypothesize that different grades of bone marrow edema (BME) and synovitis in RA can be examined and monitored in a more sensitive manner with DCE-MRI. Future treatments for RA may benefit from the application of enhanced imaging of BMEs and synovitis. DCE-MRI may also facilitate enhanced stratification and phenotyping of patients enrolled in clinical trials.

OBJECTIVES: To investigate the association between magnetic resonance imaging (MRI), macroscopic and histological assessments of synovitis in end-stage knee osteoarthritis (KOA).METHODS: Synovitis of end-stage osteoarthritic knees was assessed using non-contrast-enhanced (CE), contrast-enhanced magnetic resonance imaging (CE-MRI) and dynamic contrast-enhanced (DCE)-MRI prior to (TKR) and correlated with microscopic and macroscopic assessments of synovitis obtained intraoperatively. Multiple bivariate correlations were used with a pre-specified threshold of 0.70 for significance. Also, multiple regression analyses with different subsets of MRI-variables as explanatory variables and the histology score as outcome variable were performed with the intention to find MRI-variables that best explain the variance in histological synovitis (i.e., highest R2). A stepped approach was taken starting with basic characteristics and non-CE MRI-variables (model 1), after which CE-MRI-variables were added (model 2) with the final model also including DCE-MRI-variables (model 3).RESULTS: 39 patients (56.4% women, mean age 68 years, Kellgren-Lawrence (KL) grade 4) had complete MRI and histological data. Only the DCE-MRI variable MExNvoxel (surrogate of the volume and degree of synovitis) and the macroscopic score showed correlations above the pre-specified threshold for acceptance with histological inflammation. The maximum R2-value obtained in Model 1 was R2 = 0.39. In Model 2, where the CE-MRI-variables were added, the highest R2 = 0.52. In Model 3, a four-variable model consisting of the gender, one CE-MRI and two DCE-MRI-variables yielded a R2 = 0.71.CONCLUSION: DCE-MRI is correlated with histological synovitis in end-stage KOA and the combination of CE and DCE-MRI may be a useful, non-invasive tool in characterising synovitis in KOA.

OBJECTIVES: 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.METHOD: 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.RESULTS: 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.CONCLUSIONS: 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.

Objectives: To investigate the responsiveness to treatment and the reliability of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in rheumatoid arthritis (RA) knee joints. Methods: DCE-MRI was performed in 12 clinically active RA knee joints before and 1, 7, 30, and 180 days after intra-articular injection with 80 mg methylprednisolone. Using semi-automated image processing software, DCE-MRI parameters, including the initial rate of enhancement (IRE) and maximal enhancement (ME), were generated for three regions of interest (ROIs): 'Whole slice', 'Quick ROI', and 'Precise ROI'. The smallest detectable difference (SDD), the smallest detectable change (SDC), and intra- and inter-reader intraclass correlation coefficients (ICCs) were used to assess the reliability of DCE-MRI. Responsiveness to treatment was assessed by the standardized response mean (SRM). Results: In all patients clinical remission of the knee was achieved at day 7. All DCE-MRI parameters decreased from day 0 to day 7. Using the Quick and Precise ROI methods, respectively, IRE decreased by 63% and 69%, ME decreased by 11% and 11%, N decreased by 55% and 57%, and IRE × N decreased by 84% and 85%. The intra- and inter-reader ICCs were very high (0.96-1.00). The decrease in DCE-MRI parameters was larger than the SDC for all patients. SRM was large for all parameters, ranging from -1.04 to -2.40. When the Whole slice ROI method was used, no parameters were responsive to treatment. Conclusions: DCE-MRI analysed using semi-automatic software is a reliable and responsive tool for assessing treatment in RA knees joints. Rough manual delineation of the joint to omit enhancement artefacts is necessary.

To determine whether dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) evaluated using semi-automatic image processing software can accurately assess synovial inflammation in rheumatoid arthritis (RA) knee joints.