Discriminative Power Of Different Combinations Of Bones And Joints For Assessing Change In Rheumatoid Arthritis With Low-Field MRI

C. Peterfy1, O. Troum2, E. Olech3, P.J. Countryman1, B.M. Day4, T. Woodworth5, A. Anisfeld4, P.G. Conaghan6 1Spire Sciences and Synarc, San Francisco; 2University of Southern California, Santa Monica; 3Oklahoma University Health Sciences Center, Oklahoma City; 4Genentech, a member of the Roche Group, South San Francisco, United States; 5Roche, Welwyn; 6University of Leeds, Leeds, United Kingdom

Background: Current MRI techniques for rheumatoid arthritis clinical trials incorporate metacarpophalangeal (MCP) joints and the wrist. However, the combination of bones and joints that is most discriminative for change has not been tested.

Objectives: To examine the ability to detect significant change in joint status within 12 weeks using 0.2T MRI and RAMRIS.

Methods: As part of a phase 3b study (ACT-RAY), 62 RA patients with active, erosive RA despite methotrexate (MTX) treatment received tocilizumab (TCZ) added to MTX or switched to TCZ alone and were examined with 0.2T extremity MRI of 1 hand and wrist without contrast at baseline and at weeks 2 and 12. MRIs were scored by 2 radiologists using RAMRIS1 scales blinded to visit order. Six combinations (RAMRIS, 23 bones and 7 joints in original RAMRIS; RAMRIS+, RAMRIS + MCP1; V-Sharp, MCP1-5 + 6 wrist bones in van der Heijde-Sharp X-ray score; G-Sharp, MCP1-5 + 5 wrist bones in Genant-Sharp X-ray score [V-Sharp – lunate]; MCPs, MCP1-5; Wrist, 15 bones and 3 joints in RAMRIS) were compared for percentages of patients changing (increase or decrease) ≥ smallest detectable change (SDC)2 at week 12.

Results: Of 4625 bones and 1480 joints, only 2% and 1% were nonassessable for poor image quality, ankylosis, or surgery. MCP1 was evaluable in all cases. Inter-reader agreement was high: intra-class correlation coefficient was 0.79-0.93 for all combinations. SDC, however, varied (0.9-2.9) among the combinations, as did percentages of patients showing significant change (Figure). Interestingly, excluding 10 wrist bones from RAMRIS (G-Sharp) increased discrimination. MCPs alone was more discriminative than RAMRIS for ERO and SYN but less for OST.

Conclusion: Low-field extremity MRI is sensitive to change in ERO, OST, and SYN, detecting improvement within 12 weeks. There is potential for optimising RAMRIS by including or excluding certain joints.

References:
• Østergaard M, Peterfy C, Conaghan P, et al. OMERACT Rheumatoid Arthritis Magnetic Resonance Imaging Studies: core set of MRI acquisitions, joint pathology definitions, and the OMERACT RA-MRI scoring system. J Rheumatol 2003;30:1385-1386.
• Bruynesteyn K, Boers M, Kostense P, van der Linden S, van der Heijde D. Deciding on progression of joint damage in paired films of individual patients: smallest detectable difference or change. Ann Rheum Dis 2005;64;179-182.

Disclosure of Interest: C. Peterfy Shareholder of: Spire Sciences, Synarc, Consultant for: Abbott, Amgen, Bristol Myers-Squibb, Celgene, Novartis, Pfizer, Roche, Wyeth, Centocor, Genentech, Wyeth, Synarc, Bioclinica, Icon Medical Imaging, Employee of: Spire Sciences, O. Troum Grant/Research Support from: Roche, Amgen, Abbott, Centocor, BMS, UCB, Pfizer, Novartis, Consultant for: Roche, Amgen, Abbott, Centocor, UCB, Pfizer, Takeda, Speakers Bureau: Amgen, Abbott, BMS, Pfizer, Roche, Proctor & Gamble, Takeda, UCB, E. Olech: None Declared, P. Countryman: None Declared, B. Day Employee of: Genentech, a member of the Roche Group, T. Woodworth Employee of: Roche, A. Anisfeld Employee of: Genentech, a member of the Roche Group, P. Conaghan Grant/Research Support from: Pfizer, Speakers Bureau: Abbott, AstraZeneca, BMS, Centocor, Merck, Novartis, Pfizer, Roche

Citation: Ann Rheum Dis 2010;69(Suppl3):119

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