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British Journal of Rheumatology 1998;37:854–861
ASSESSMENT OF DISEASE ACTIVITY IN RHEUMATOID ARTHRITIS USING MAGNETIC RESONANCE IMAGING: QUANTIFICATION OF PANNUS VOLUME IN THE HANDS H. SUGIMOTO, A. TAKEDA* and S. KANO* Departments of Radiology and *Medicine, Division of Clinical Immunology, Jichi Medical School, 3311 Minamikawachi-machi, Kawachi-gun, Tochigi-ken 329-04, Japan SUMMARY We attempted to assess whether pannus volume measured by magnetic resonance imaging (MRI ) can be used as an indicator of disease activity in rheumatoid arthritis (RA). Eleven women (mean age 46 yr) with uncontrolled RA were studied for 1 yr. Pannus formation in both hands was quantified using MRI at the start of the study, and at 6 and 12 months thereafter. The volume of enhancing pannus ( VEP) was compared with changes in the radiological scores, grip strength, joint tenderness counts, joint swelling counts, erythrocyte sedimentation rate ( ESR), and serum C-reactive protein (CRP). Patients were classified into three groups based on VEP changes between 0 and 12 months: unchanged (n = 2), decreased (n = 6) and increased (n = 3). VEP at 6 months and at 12 months differed significantly between the three groups. No statistically significant differences were found between the groups in radiographic scores, physical parameters or laboratory parameters despite the fact that some of these parameters changed in the direction indicated by the changes in VEP. VEP can be used as a new indicator to assess disease activity in individual RA patients and, using this parameter, treatment outcome can be assessed in fewer subjects than with traditional measures. K : Rheumatoid arthritis, Magnetic resonance imaging, Radiology, Gadolinium, Quantification.
F the interpretation of clinical trials and treatment results in patients with rheumatoid arthritis (RA), it is important to standardize measurement of disease activity. Quantifying the formation of pannus, the primary target tissue in RA treatment, has been considered for assessing disease activity in individual RA patients. Several authors have studied the potential value of magnetic resonance imaging (MRI ) for this purpose [1–5]. Longitudinal changes in pannus volume in individual patients have been investigated up to 6 months after treatment [2, 6 ]. These studies suggested that MRI-determined pannus volume has predictive value with respect to treatment outcome in RA. Articular involvement in RA can occur in various joints, including the hand, wrist, elbow, foot and other joints. However, evaluation of the hands is particularly important because the features they exhibit are frequently a reflection of the patient’s overall disease condition, whether in early, late or progressive stages [7]. As for the anatomical MRI site for evaluating RA activity, the hands are considered to be the most appropriate articulation. The purpose of this investigation was to compare the chronological changes in pannus volume with the changes in radiographic, physical and laboratory parameters in a relatively long follow-up period in order to assess the relationship between changes in MRIdetermined pannus volume and changes in radiological, clinical and laboratory parameters, and to find whether MRI-determined pannus volume can be used as an indicator of disease activity in RA.
PATIENTS AND METHODS Patient profile Eleven women (age range 21–60 yr, mean age 46 yr) with RA were enrolled in this study. They had been diagnosed according to the ARA 1987 revised criteria for the classification of RA [8] and had been treated by one of the authors prior to enrolment. The average duration of RA was ~5 yr (range 1–14 yr) at the time of entry into this study. Seven patients were seropositive and four were seronegative. The patients met the following conditions: (1) their diseases were considered to be uncontrolled, i.e. the necessary degree of disease activity at enrolment was confirmed by a finding of five or more swollen joints, five or more tender joints, or one of the following two laboratory criteria: a Westergren erythrocyte sedimentation rate ( ESR) of at least 30 mm/h (normal, 10 mg/ml (normal,
