High-resolution peripheral quantitative computed tomography for the assessment of acro-osteolysis and calcinosis in patients with systemic sclerosis

Abstract

ObjectiveTo assist the development of future treatments in systemic sclerosis (SSc), the development of reliable outcome measures is pivotal. We aimed to evaluate the use of high-resolution peripheral quantitative CT (HR-pQCT) for visualization and gradation of acro-osteolysis (AO) and calcinosis compared to conventional hand radiographs (CR) in patients with SSc. MethodsHR-pQCT scans of the 2nd to 4th fingers, CR, nail fold capillaroscopy, and a clinical examination were conducted. Images were reviewed for the presence and degree of AO and calcinosis according to semiquantitative grading scales. ResultsForty patients were included. Fourteen had AO according to CR, whereas HR-pQCT revealed AO in 18 patients. The sensitivity and specificity of classifying patients as having AO by HR-pQCT when CR was used as reference were 93% (95% CI: 66–99%) and 80% (95% CI: 59–93%), respectively. By CR and with HR-pQCT as reference, the sensitivity and specificity were 72% (95% CI: 47–90%) and 95% (95% CI: 76–99%). Patients with AO had more or larger calcifications than patients without AO according to the proposed HR-pQCT grading system, with a median grade of 2 (IQR: 1–3) versus 0 (IQR: 0–1) (P<0.01). Grade 3 changes were observed exclusively in patients with AO (n=6/14, 42.9%). Assessment of AO and calcinosis by HR-pQCT demonstrated moderate to excellent test-retest reliability. ConclusionHR-pQCT allowed precise and reliable classification and grading of acro-osteolysis and acral calcinosis. The modality could prove helpful for detecting and monitoring these lesions as well as facilitating early diagnosis and guide treatment of these patients.