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

To elucidate the F-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). 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 F-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. Compared with the anti-MDA5- group, the patients in the anti-MDA5+ group showed higher bilateral lung SUVmax ( = 0.029), higher SUVmax of spleen ( = 0.011), and bone marrow ( = 0.048). Significant correlations between the spleen SUVmax and serum ferritin levels ( = 0.398, < 0.001), erythrocyte sedimentation rate (ESR) ( = 0.274, = 0.023), platelet count ( = -0.265, = 0.028), myositis disease activity assessment score ( = 0.332, = 0.005), bone marrow SUVmax ( = 0.564, < 0.001), and bilateral lung SUVmax ( = 0.393, < 0.001) were observed. F-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.