A Pilot Study of 10 Patients Measuring High And Low Field MRI Findings and Clinical Outcomes on Patients with Rheumatoid Arthritis Treated With Abatacept

N.B. Gaylis1, S. Needell2, D. Rudensky2 1ARTHRITIS & RHEUMATIC DISEASE SPECIALTIES, AVENTURA; 2BOCA RADIOLOGY GROUP, BOCA RATON, United States

Background: Abatacept has been shown to reduce osteitis and erosions in patients with RA (1). Low and high field MRI systems have independently been shown to be sensitive to the measurement of osteitis and erosions in RA patients (pts) (2).

Objectives: To explore the comparative capabilities of low (0.3T) vs. high (1.5T) field MRI in the detection of changes in wrist and hand findings following treatment with abatacept with MTX in RA.

Methods: Ten RA pts who had been unresponsive to either MTX alone or in conjunction with an anti-TNF agent with either osteitis or erosions on baseline MRI were treated for 26 weeks with abatacept infusions on days 1, 15, 28, and every 28 days thereafter. 0.3T and 1.5T MRI scans of the wrist and hand were obtained at weeks 0, 4 and 26 and scored by 2 blinded radiologists using OMERACT/RAMRIS system. Imaging results were compared with clinical response using ACR response, HAQ, DAS28, and physician global scores and plain films.

Results: Both MRI systems were effective in detecting changes in osteitis and erosions. The 1.5T STIR sequence was more sensitive than 0.3T in detecting osteitis. The 0.3T T1W sequence outperformed the 1.5T fat-suppressed T1W sequence in quantifying erosions.
Of the 6 pts with osteitis on baseline imaging, scores decreased through 26 weeks in all, and only 1 additional site of osteitis developed. Mean total osteitis score at baseline was 46.5 which increased by 16% to 50 at week 4 due to progression in 3 patients. Osteitis ultimately regressed in all patients and by 26 weeks the mean total osteitis scores had decreased by 78% from baseline to 10.5. Of these patients, 5/6 had significant clinical responses. None of the 4 patients without osteitis at baseline MRI showed any MRI changes during the study; 3 did not achieve an ACR20 clinical response and 1 had a significant ACR response.
Erosion scores at 6 sites in 4 patients had regressed by 26 weeks; one new erosion developed. Changes in the mean total erosion scores(76/80/72 at weeks 0/4/26, respectively) were less dramatic than changes seen with osteitis scores.
Neither disease duration nor prior use of anti-TNF appeared to have any significant relevance. No x-ray changes were identified during the study. There were no clinically significant adverse effects.

Conclusion: Both low and high field MRI effectively measured the effects and benefits of abatacept treatment during a 26 week period. Patients with baseline osteitis tended to have a more robust clinical and MRI response. Subsequent studies should confirm these findings and better establish the time course of improvements detected by MRI as an outcome measurement and predictor of response to abatacept therapy.

References:

P. Emery, Ann Rheum Dis, published online November 23, 2009. doi: 10.1136/ard.2009.119016
Ejberg B et al, Annual Rheumatic Disease 2005;64(9)1280-1287

Disclosure of Interest: N. GAYLIS Grant/Research Support from: BRISTOL-MYERS SQUIBB, Speakers Bureau: ROCHE-GENENTECH, CENTOCOR, S. NEEDELL: None Declared, D. RUDENSKY: None Declared

Citation: Ann Rheum Dis 2010;69(Suppl3):309

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