Dynamic gadolinium-enhanced magnetic resonance imaging allows accurate assessment of the synovial inflammatory activity in rheumatoid arthritis knee joints: a comparison with synovial histology

Abstract

Objective: 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.

Methods: In 17 RA patients undergoing knee surgery, the average grade of histological synovial inflammation was determined from four biopsies obtained during surgery. A preoperative series of T₁-weighted dynamic fast low-angle shot (FLASH) MR images was obtained. Parameters characterizing contrast uptake dynamics, including the initial rate of enhancement (IRE), were generated by the software in three different areas: (I) the entire slice (Whole slice); (II) a manually outlined region of interest (ROI) drawn quickly around the joint, omitting large artefacts such as blood vessels (Quick ROI); and (III) a manually outlined ROI following the synovial capsule of the knee joint (Precise ROI). Intra- and inter-reader agreement was assessed using the intra-class correlation coefficient (ICC).

Results: The IRE from the Quick ROI and the Precise ROI revealed high correlations to the grade of histological inflammation (Spearman’s correlation coefficient (rho) = 0.70, p = 0.001 and rho = 0.74, p = 0.001, respectively). Intra- and inter-reader ICCs were very high (0.93–1.00). No Whole slice parameters were correlated to histology.

Conclusion: DCE-MRI provides fast and accurate assessment of synovial inflammation in RA patients. Manual outlining of the joint to omit large artefacts is necessary.

Acknowledgements

We thank Schering Diagnostika, Denmark, for providing the contrast agent. The Parker Institute has received financial support from the Oak Foundation. This study was supported by unrestricted research grants from Abbott Laboratories. The Foundation of 17-12-81, the University of Copenhagen, the Danish Rheumatism Association, the Thomas and Elisabeth Frølund Nielsen Foundation, the Danish Medical Research Council, Johann and Hanne Weimann f. Seedorf’s grant and the Danish Hospital Foundation for Medical Research, Region of Copenhagen, the Faroe Islands and Greenland are thanked for financial support.