To develop novel quantitative and semiquantitative bone erosion measures at metacarpophalangeal (MCP) and wrist joints in patients with rheumatoid arthritis (RA) using high-resolution peripheral quantitative computed tomography (HR-pQCT), and to correlate these measurements with disease duration and bone marrow edema (BME) patterns derived from magnetic resonance imaging (MRI).
Sixteen patients with RA and 7 healthy subjects underwent hand and wrist HR-pQCT and 3-Tesla MRI. Bone erosions of the MCP2, MCP3, and distal radius were evaluated by measuring maximal erosion dimension on axial slices, which is a simple and fast measurement, and then were graded (grades 0-3) based on the maximal dimension. Correlation coefficients were calculated between (1) sum maximal dimensions, highest grades, and sum grades of bone erosions; (2) erosion measures and the clinical evaluation; (3) erosion measures and BME volume in distal radius.
The inter- and intrareader agreements of maximal erosion dimensions were excellent (intraclass correlation coefficients 0.89, 0.99, and root mean square error 9.4%, 4.7%, respectively). Highest grades and sum grades were significantly correlated to sum maximal dimensions of all erosions. Number of erosions, sum maximal erosion dimensions, highest grades, and sum grades correlated significantly with disease duration. Number of erosions, sum maximal dimensions, and erosion grading of the distal radius correlated significantly with BME volume.
HR-pQCT provides a sensitive method with high reader agreement in assessment of structural bone damage in RA. The good correlation of erosion measures with disease duration as well as BME volume suggests that they could become feasible measures of erosions in RA.