Imaging calcinosis in patients with systemic sclerosis by radiography, computerised tomography and magnetic resonance imaging.
Objective outcome measures are needed to facilitate clinical trials of much needed treatments for calcinosis in systemic sclerosis (SSc). Our primary aim was to compare radiography, computed tomography (CT) and magnetic resonance imaging (MRI) to measure calcinotic lesions. Secondary objectives included to examine reproducibility of radiography and MRI, and inter-rater reliability of MRI. 15 patients with SSc and clinically apparent calcinosis were studied. On one hand, radiography, CT and MRI were performed. The number (all techniques), area (radiography) and volume (CT and MRI) of calcinotic areas were extracted by 'blinded' musculoskeletal radiologists. No significant difference (P = 0.289) in the mean (SD) number of lesions (per hand) was seen between radiography: 5.4 (4.6), CT: 6.3 (6.5) and MRI: 5.2 (3.9). Mean (SD) lesion volumes were systematically higher as measured by CT: 656.7 (1939.9) mm3 compared to MRI: 442 (1083.2) mm3. Radiographic area was highly correlated (P = <0.0001) with volume for both CT and MRI (rho=0.91 and 0.87, respectively). It was possible to measure calcinotic lesions by radiography, CT and MRI, with CT volume being higher than MRI volume. Radiographic area was highly correlated with CT and MRI volume, suggesting that low cost radiographs may give comparable information to 3-dimensional imaging. Our findings provide further insight into the development of objective outcome measures to facilitate future calcinosis clinical trials.