A Novel Approach to Monitoring Calcinosis in Juvenile Dermatomyositis: Serial Low-Dose Whole-Body CT

Abstract

Objectives Evaluating the overall impact of calcinosis and response to therapy in juvenile dermatomyositis (JDM) remains challenging, primarily relying on physician assessments or plain X-rays.[1] We aimed to explore the use of an ultra-low-dose protocol for whole-body CT imaging as a novel approach to monitor the distribution and burden of calcinosis in a cohort of patients with JDM. Methods The study focused on patients diagnosed with probable or definite JDM as per the Bohan and Peter criteria, followed at the Hospital for Sick Children during the years January 2000 to September 2025, who developed calcinosis based on physical examination or previous imaging studies. Eligible patients who have undergone at least 2 serial non-contrast, ultralow-dose whole-body CT scans during their follow-up were included in the study. Imaging data analysis was conducted to detect the regional distribution and volume of calcinosis, assess changes over time, and compare serial CT scans performed for each included patient. Results Out of the 256 patients with JDM, 54 (21%) developed calcinosis during follow-up. Among these, 3 patients with a median age of 7.8 years (IQR 7.2-9.9) at JDM diagnosis underwent 2 serial non-contrast, ultralow-dose whole-body CT scans each to assess their calcinosis during their follow-up. Two of the cases were positive for anti-NXP2, while case 2 had negative myositis-specific antibody serology. The median duration of disease at the development of calcinosis was 17 months (IQR 8.5-22). The median duration between the first and second CT scans was 12 months (IQR 9.5-13). In all 3 cases, follow-up CT scans revealed an increase in the size and distribution of previously observed deposits, along with the appearance of new calcification clusters (Figure 1). Furthermore, the 3D reconstruction of confluent calcinosis revealed a distinct structure and distribution of certain densities compared to earlier evaluations conducted through X-ray and physical examination. This resulted in an intensification of treatment in each of the 3 cases. The median effective dose for a low-dose CT scan used was significantly lower than the standard protocol, about 10 times less than in adults. Conclusion An ultra-low-dose protocol for whole-body CT can serve as a safe and objective, valuable tool for monitoring changes in calcinosis, thereby contributing to improved patient care and outcomes. References [1.] Yi BY. Pediatr Rheumatol Online J 2025;23:44.