Background/Purpose: Calcinosis is a condition in which calcium salts are deposited in and around soft tissue and is observed in up to 30% of adult dermatomyositis (DM) patients and up to 70% of juvenile dermatomyositis (JDM) patients. Clinical assessment of calcinosis is usually conducted with a physical assessment or through radiographic imaging consisting of plain X-rays. However, due to the two-dimensional nature of these X-ray images, much is still not known about the spatial properties of calcification and the relative densities of the lesions. The objective of the study was to utilize whole-body computed tomography (CT) imaging and calcium scoring techniques as tools for calcinosis assessment in a prospective cohort of patients with DM and JDM.

Methods: Thirty-one patients (14 DM and 17 JDM) who fulfilled Bohan and Peter Classification criteria as probable or definite DM, the EULAR-ACR for definite DM, and with calcinosis identified by physical examination or prior imaging studies were included. Non-contrast whole-body CT scans were obtained using generic and ultra-low dose radiation procedures. Scans were read qualitatively and quantitated using imaging software. We calculated the sensitivity and specificity of calcinosis detection against a physician physical exam. We quantified calcinosis burden using the Agatston scoring technique.

Results: We identified five distinct calcinosis patterns: Clustered, Disjoint, Interfascial, Confluent, and Fluid-filled. Patients often exhibited multiple types of calcification. The most common patterns were the Clustered and Interfascial type seen in 19 and 7 patients, respectively. Novel locations of calcinosis were observed, including the cardiac tissue, pelvic and shoulder bursa, and the spermatic cord. The regions of highest and lowest calcinosis occurrence were the proximal legs (86.7%) and head & neck (40%), respectively. There was moderate agreement for calcinosis detection between the physical exam and CT (κ = 0.45, 95% confidence interval [95% CI] 0.38, 0.52). Physician physical exams had a sensitivity of 59% and a specificity of 90% compared to CT detection. Quantitative measures using Agatston scoring for calcinosis were used in regional distributions across the body. Total average Agatston score, normalized by patient height, was 3128.52 ± 5868.52 (adult DM: 1741.93 ± 2347.21, JDM: 4630.67 ± 8024.76), with no difference by clinical subgroup. A higher calcium score correlated with higher Physician Global Damage, Calcinosis Severity scores, and disease duration.

Conclusion: Whole-body CT scans and the Agatston scoring metric define distinct calcinosis patterns and provide novel insights relating to calcinosis in DM and JDM patients. Physician physical examinations underrepresented the presence of calcium. Calcium scoring of CT scans correlated with clinical measures, which suggests that this method may be used to assess calcinosis and follow its progression.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/assessing-calcinosis-in-dermatomyositis-with-computed-tomography-and-calcium-scoring/