Reducing invasiveness, duration, and cost of magnetic resonance imaging in rheumatoid arthritis by omitting intravenous contrast injection -- Does it change the assessment of inflammatory and destructive joint changes by the OMERACT RAMRIS?

OBJECTIVE

Gadolinium (Gd)-enhanced magnetic resonance imaging (MRI) provides highly sensitive assessment of inflammatory and destructive changes in rheumatoid arthritis (RA) joints, but intravenous (IV) Gd injection prolongs examination time and increases cost, invasiveness, and patient discomfort. We explored to what extent RA joint pathologies in wrists and metacarpophalangeal (MCP) joints can be reliably assessed by unenhanced MRI images compared with Gd-enhanced MRI as the reference method.

METHODS

MRI data sets from 2 RA substudies were scored according to preliminary OMERACT RA MRI scoring system (RAMRIS): Substudy A included 1.0 T/1.5 T MR images from 40 RA patients, which were scored twice by 2 experienced readers. Substudy B included 0.2 T dedicated extremity MRI (E-MRI) images from 55 patients, scored twice by one experienced reader. The first reading included only unenhanced images, whereas complete image sets were available for the second reading.

RESULTS

Gd contrast injection appeared unimportant to MRI scores of bone erosions and bone edema in RA wrist and MCP joints. However, when post-Gd MRI was considered the standard reference, MRI without Gd provided only moderate to high agreement concerning assessment of synovitis, and omitting the post-Gd acquisitions increased the interreader variation on synovitis scores. Low-field (0.2 T) E-MRI in these exercises provided a lower sensitivity of unenhanced imaging for synovitis than MRI using higher-field strengths.

CONCLUSION

Omitting IV contrast injection did not change scores of bone erosions and bone edema, but decreased the reliability of synovitis scores. However, this disadvantage may for some purposes be outweighed by the possibility to assess more joints and/or greater feasibility.