Update on research and future directions of the OMERACT MRI inflammatory arthritis group

The OMERACT Magnetic Resonance Imaging (MRI) Task Force has developed and evolved the psoriatic arthritis MRI score (PsAMRIS) over the last few years, and at OMERACT 10, presented longitudinal evaluation by multiple readers, using PsA datasets obtained from extremity MRI magnets. Further evaluation of this score will require more PsA imaging datasets. As well, due to improved image resolution since the development of the original rheumatoid arthritis MRI scoring system (RAMRIS), the Task Force has worked on semiquantitative assessment of joint space narrowing, and developed a reliable method as a potential RAMRIS addendum, although responsiveness will need to be evaluated. One of the strengths of MRI is the ability to detect subclinical synovitis, so the group worked on obtaining low disease activity/clinical remission datasets from a number of international centers and presented cross-sectional findings. Subsequent longitudinal evaluation of this unique resource will be a major continuing focus for the group.

Patterns of magnetic resonance imaging bone erosion in rheumatoid arthritis--which bones are most frequently involved and show the most change?

OBJECTIVE

To investigate by magnetic resonance imaging (MRI) which bones in wrists and metacarpophalangeal (MCP) joints most frequently show bone erosions, and which most frequently demonstrate erosive progression, in early and established rheumatoid arthritis (RA).

METHODS

MRI datasets from 258 RA patients [126 with early RA (disease duration < 6 months)] were analyzed, of whom 223, including 126 with early RA, had 1-year followup MRI. All patients had MRI of one wrist, whereas 86 patients had additional images of 2nd-5th MCP joints, and 46 patients additional images of the contralateral wrist. MRI were evaluated blinded by one reader, according to the OMERACT RA MRI scoring system (RAMRIS) for erosions, and presence/absence of erosions was noted in each bone, as was presence/absence of erosive progression.

RESULTS

The capitate, ulna, lunate, triquetrum, and scaphoid were the 5 bones with both most frequent baseline erosions and most frequently demonstrated erosive progression. No bones were without erosions. Patterns of erosions and progression were similar in early and established RA. No major difference between dominant and nondominant wrists was detected. In the fingers, the 2nd-3rd MCP joint most frequently displayed erosions and erosive progression.

CONCLUSION

The distribution and frequency of bone erosion and erosive progression as detected by MRI in RA wrists and MCP joints were identified. No pattern differences between early versus established disease and dominant versus nondominant sides were detected. No bones showed erosive progression. Thus, no self-evident simplification of the RAMRIS erosion score was identified. Bone involvement patterns may be considered, when joints are selected for MRI protocols for clinical trials and practice.

Bone edema on magnetic resonance imaging is an independent predictor of rheumatoid arthritis development in patients with early undifferentiated arthritis

OBJECTIVE

To study magnetic resonance imaging (MRI) as a tool for early diagnosis of rheumatoid arthritis (RA) in patients with early undifferentiated arthritis (UA).

METHODS

Patients (n = 116) without a specific rheumatologic diagnosis, but with ≥2 tender joints and/or ≥2 swollen joints among the metacarpophalangeal, proximal interphalangeal, wrist, or metatarsophalangeal (MTP) joints for >6 weeks but <24 months, underwent clinical, biochemical, conventional radiographic, and MRI examinations and were followed up for >12 months for the final diagnosis of RA or non-RA. Based on univariate analyses, clinical, biochemical, and imaging parameters were selected for inclusion as explanatory variables in multiple logistic regression analysis, with development of RA as the dependent variable. A prediction model was developed, and its performance was tested and compared with that of a previous model developed by van der Helm-van Mil et al (the vdHvM model).

RESULTS

Of the 116 patients with early UA, 27 (23.3%) developed RA. When the prediction model was applied, which included as explanatory variables presence of hand arthritis, positivity for rheumatoid factor (RF), morning stiffness lasting >1 hour, and the Outcome Measures in Rheumatology Clinical Trials MRI summary score for bone edema in the MTP and wrist joints, the outcome of RA or non-RA was correctly identified in 82% of the patients (sensitivity 81%, specificity 82%). Another cutoff value for the prediction index in the model would allow a higher specificity (98%) and higher accuracy (83%), but lower sensitivity (36%). With the vdHvM model, RA/non-RA was predicted in 60.2% of the population.

CONCLUSION

MRI evidence of bone edema in the MTP and wrist joints is an independent predictor of future RA in patients with early UA. A prediction model that includes the variables clinical hand arthritis, morning stiffness, positivity for RF, and bone edema on MRI in the MTP and wrist joints correctly identified the development or lack of development of RA in 82% of patients.

Detection of rheumatoid arthritis bone erosions by two different dedicated extremity MRI units and conventional radiography

OBJECTIVES

To compare the ability of two different dedicated extremity MRI (E-MRI) units and conventional radiography (CR) for identifying bone erosions in rheumatoid arthritis (RA) metacarpophalangeal (MCP) and wrist joints.

METHODS

CR and two MRI examinations (using 0.2 T Esaote Artoscan and 0.2 T portable MagneVu MV1000 units) of 418 bones in the dominant wrist and second to fifth MCP joints of 15 patients with RA and 4 healthy controls were performed and evaluated blindly for bones being visible and for erosions.

RESULTS

In MCP joints, MagneVu visualised 18.5% of bones entirely and 71.1% were 67-99% visualised. In wrists, MagneVu visualised 1.5% of bones entirely, 39.8% were 67-99% visualised and 19% were not visualised at all. Artoscan and CR visualised all bones entirely. Artoscan, MagneVu and CR found 22, 19 and 15 bones with erosions in MCP joints and 66, 40 and 13 bones with erosions in wrist joints, respectively. With the previously validated Artoscan unit as standard reference, MagneVu and CR had sensitivities of 0.82 and 0.55, respectively, in MCP joint bones and 0.41 and 0.14 in wrist bones. Specificities of CR and MagneVu were comparable (0.82-0.99). The MagneVu unit was particularly more sensitive than CR for metacarpal heads and carpal bones. MagneVu MRI and CR detected 100% and 89%, respectively, of large erosions (Outcome Measures in Rheumatoid Arthritis Clinical Trials-Rheumatoid Arthritis MRI Scoring System (OMERACT-RAMRIS) score >1 on Artoscan) in MCP joints and 69% and 15.8% of large erosions in wrists.

CONCLUSIONS

Both E-MRI units detected more erosions than CR, in particular due to a higher sensitivity in metacarpal heads and carpal bones. The MagneVu unit detected fewer erosions than the Artoscan unit due to a lower average image quality and a smaller proportion of bones being visualised.