EXAMINING THE UTILITY OF E-MRI WITH A REDUCED FIELD OF VIEW: AN IMAGING COMPARISON STUDY IN SEVERE RHEUMATOID ARTHRITIS

[2007] [SAT0444] EXAMINING THE UTILITY OF E-MRI WITH A REDUCED FIELD OF VIEW: AN IMAGING COMPARISON STUDY IN SEVERE RHEUMATOID ARTHRITIS

J.E. Freeston, S. Dass, E.M. Vital, E.M.A. Hensor, S.P. Stewart, P. Emery, P.G. Conaghan Academic Unit of Musculoskeletal Disease, University of Leeds, Leeds, United Kingdom

Background: Severe RA produces unique challenges when assessing disease activity and damage. Radiographs can be difficult to interpret because of joint deformities. Using high field MRI can be problematic because of the difficult patient positioning required. The use of extremity MRI (eMRI) therefore offers the possibility of improved disease assessment with greater patient tolerability.
Objectives: The aim of this cross-sectional study was to compare an eMRI machine with a reduced field of view (eMRI-RV) to plain film radiography and high field MRI, using the latter as the gold standard. The ability to identify erosions was compared between the 3 modalities in a cohort of severe RA patients.
Methods: 15 patients (87% female, median age 56 years) with active RA (DAS28 > 5.1) underwent plain film radiography of hands, eMRI-RV (0.2 Tesla MagneVu MV 1000 machine) and high field MRI (1.5T Phillips machine, using a dedicated coil) of unilateral wrist joints. All patients were taking leflunomide and had active disease despite anti-TNF therapy.
The high field MRI images were evaluated according to the OMERACT RAMRIS score [1] and the eMRI-RV images using our RAMRIS-RV scoring system. The RAMRIS-RV scoring system does not include the base of metacarpals 1 and 5, trapezium and pisiform as these are infrequently visualised.
Results: Of 86 comparable joint areas, high field MRI identified 70 erosions, eMRI-RV 32 and radiography 4.
With high field MRI considered as the reference method, the sensitivity, specificity and accuracy of eMRI-RV for erosions were 46%, 94% and 55%, and the corresponding values for X-ray were 6%, 100% and 23%.
The sensitivity of eMRI-RV was maximal at the distal radius (83%) and ulna (80%).
The intra-class correlation coefficient (ICC) between eMRI-RV and high field MRI scores was 0.689 (p<0.001).
Conclusion: Using high field MRI as the gold standard, sensitivity of erosion detection was markedly higher for eMRI-RV than radiography, with similarly high levels of specificity. Such a reduced field of view eMRI machine is able to provide more information on bone erosions than radiography, although it is less sensitive than high field MRI.
References: 1. Ostergaard M, Peterfy C, Conaghan P, McQueen F, Bird P, Ejbjerg B, 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(6):1385-6.

Diagnostics and imaging procedures

Citation: Ann Rheum Dis 2007;66(Suppl II):564