Radiological Characteristics of Patients With Anti-MDA5–Antibody-Positive Dermatomyositis in 18F-FDG PET/CT: A Pilot Study

Abstract

<b>Objective:</b> To elucidate the ¹⁸F-fluorodeoxyglucose (FDG) PET/CT characteristics and its prognostic value in the patients with anti-melanoma differentiation associated protein 5 antibody positive (anti-MDA5+) dermatomyositis (DM). <b>Methods:</b> This retrospective cross-sectional study included 26 patients with anti-MDA5+ DM and 43 patients with anti-MDA5 negative (anti-MDA5-) idiopathic inflammatory myopathy (IIM) who were examined by ¹⁸F-FDG PET/CT from January 1, 2017 to December 31, 2020. The maximum standardized uptake value (SUVmax) of multiple organs and other clinical characteristics of the patients were measured and analyzed. <b>Results:</b> Compared with the anti-MDA5- group, the patients in the anti-MDA5+ group showed higher bilateral lung SUVmax (<i>p</i> = 0.029), higher SUVmax of spleen (<i>p</i> = 0.011), and bone marrow (<i>p</i> = 0.048). Significant correlations between the spleen SUVmax and serum ferritin levels (<i>r</i> = 0.398, <i>p</i> < 0.001), erythrocyte sedimentation rate (ESR) (<i>r</i> = 0.274, <i>p</i> = 0.023), platelet count (<i>r</i> = -0.265, <i>p</i>= 0.028), myositis disease activity assessment score (<i>r</i> = 0.332, <i>p</i> = 0.005), bone marrow SUVmax (<i>r</i> = 0.564, <i>p</i> < 0.001), and bilateral lung SUVmax (<i>r</i> = 0.393, <i>p</i> < 0.001) were observed. <b>Conclusion:</b> ¹⁸F-FDG PET/CT was found valuable in quantifying the pulmonary focal inflammation and potentially unveil the distinctive characteristics and pathophysiological mechanisms in the patients with anti-MDA5+ DM.