POS0835 VOLUMETRIC QUANTIFICATION OF SYSTEMIC SCLEROSIS-ASSOCIATED CALCINOSIS CUTIS
Authors: M. Hinchcliff, M. Wu, I. Odell, X. Papademetris, A. Feher, Y. Zhao, H. Lee, M. Lempel, A. Wang, G. Galiana, C. Van Horn, B. Gunes, S. E. Kujawski
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Calcinosis cutis (CC) is a debilitating feature of systemic sclerosis (SSc) that occurs in 18-49% of patients depending on the definition and patient population [1]. Sodium thiosulfate 25% solution (STS), a chelating agent administered topically or intralesionally, has been associated with clinical improvement in lesions up to 2 cm, but no prospective controlled trials have been conducted. Feasible, quantitative, and validated outcomes need to be developed to permit valid clinical trials. <h3>Objectives:</h3> We sought to assess the feasibility and utility of applying open-source BioImage Suite software developed at our institution to computed tomography (CT) images of symptomatic CC lesions as a quantitative outcome. We hypothesized that BioImage software would enable accurate volumetric quantification of CC lesions on CT imaging obtained before and after treatment. <h3>Methods:</h3> Two SSc patients with painful extensive CC received monthly intralesional 25% STS treatment. Pre- and post-treatment CT images of involved skin were obtained. Exams were preprocessed using a K-means clustering approach whereby image pixels were given a score of 0, 1, or 2. Trained operators used the paintbrush feature of BioImage software to annotate/"paint" pixels containing CC on each CT exam slice. The volume of interest tool was applied to sum the volume of painted pixels enabling precise CC quantification. The reproducibility of the approach was tested by obtaining and annotating an additional post-treatment CT exam one week later. <h3>Results:</h3> In Case 1, baseline arm photographs were obtained and CT imaging showed a 12 cm indurated sheet-like plaque, and five 2-5 mm, CC lesions (Figure 1A, B, E). Seven months of therapy resulted in reduced pain and improved cosmesis (Figure 1C). BioImage software applied to pre- and post-treatment CT images demonstrated a reduction in CC volumes [4.43 cm<sup>3</sup> to 3.16 cm<sup>3</sup> (28%)]. Quantification of CC lesional volumes on repeat CT imaging one week following initial post-treatment imaging demonstrated a volume difference of 0.1 cm<sup>3</sup> (3%) (Figure 1F). In Case 2, baseline bilateral buttock photographs were obtained and CT imaging showed a plaque-like lesion on the left with four 2-3 mm hard white dermal nodules, and tumoral calcinosis on the right (Figure 2A, B, C). After six monthly injections over the period of nine months, pain decreased in the left buttock while the lesion decreased from 5 cm to 3 cm, the right buttock became less painful, and post-treatment CT images were obtained (Figure 2D, E). BioImage software applied to pre- and post-treatment CT images of the left buttock demonstrated a reduction in CC volumes [33.1 cm<sup>3</sup> to 7.94 cm<sup>3</sup> (76%)], and the right buttock decreased from [19.7 cm<sup>3</sup> to 16.9 cm<sup>3</sup> (14%)] seen in Figure 2F. <h3>Conclusion:</h3> We report that BioImage software applied to CT exams of CC lesions in patients with SSc may be a feasible and reproducible approach for quantification. In two patients treated with intralesional STS, improvement in symptoms and physical appearance of lesions mirrored volumetric reductions in CC. Thus, BioImage software applied to CT images of CC may be a useful outcome measure for clinical care and future trials. <h3>REFERENCES:</h3> [1] Valenzuela, A., P. Song, and L. Chung, Calcinosis in scleroderma. Curr Opin Rheumatol, 2018. 30(6): p. 554-561. <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> Monqiue Hinchcliff Consulted for Boehringer Ingelheim, Funded research with Boehringer Ingelheim and Kadmon, Megan Wu: None declared, Ian Odell President of Plythera, Inc., unrelated to this project., Xenophon Papademetris: None declared, Atilla Feher: None declared, Yize Zhao: None declared, Hyojeong Lee: None declared, Matthew Lempel: None declared, Annie Wang: None declared, Gigi Galiana: None declared, Cassandra Van Horn: None declared, Baran Gunes: None declared, Sophia Esme Kujawski: None declared.