Total metabolic lesion volume of lymph nodes measured by (18)F-FDG PET/CT: a new predictor of macrophage activation syndrome in adult-onset Still’s disease

BACKGROUND: To investigate the potential utility of quantitative parameters obtained by (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) in the assessment of disease severity and the occurrence of macrophage activation syndrome (MAS) in adult-onset Still’s disease (AOSD). METHODS: Fifty-seven patients with AOSD who underwent pre-treatment (18)F-FDG PET/CT were recruited in this study and compared with 60 age- and sex-matched healthy controls. Clinical features and laboratory data were recorded. The systemic score was assessed to determine the disease severity. The maximal standardized uptake value (SUV(max)), metabolic lesion volume (MLV), and total lesion glycolysis (TLG) were used to evaluate the involved organs and tissues that abnormally accumulated (18)F-FDG. Multivariate analysis was performed to identify the PET/CT-derived risk factors contributing to the AOSD-related MAS, and their diagnostic efficiency was evaluated. RESULTS: High (18)F-FDG accumulation was observed in the bone marrow (SUV(max) median, 5.10), spleen (SUV(max) median, 3.70), and lymph nodes (LNs, SUV(max) median, 5.55). The SUV(max) of the bone marrow (rho = 0.376, p = 0.004), SUV(max) of the spleen (rho = 0.450, p < 0.001), TLG(total) of LNs (rho = 0.386, p = 0.017), and MLV(total) of LNs (rho = 0.391, p = 0.015) were correlated with the systemic score. The SUV(max) of the spleen (p = 0.017), TLG(total) of LNs (p = 0.045), and MLV(total) of LNs (p = 0.012) were higher in patients with MAS than in those without MAS. A MLV(total) of LNs > 62.2 (OR 27.375, p = 0.042) was an independent predictive factor for MAS with a sensitivity of 80.0% and a specificity of 93.9%. CONCLUSIONS: The glucose metabolic level of the spleen could be an effective and easy-to-use imaging indicator of disease severity, and MLV(total) of LNs > 62.2 was a strong predictor of MAS occurrence in patients with AOSD.