Role of splenic and bone marrow uptake at F-FDG PET/CT for the assessment of large vessels vasculitis and the influence of glucocorticoids therapy on their values.

Introduction: To assess the relationship between splenic and bone marrow (BM) uptake with the presence of large vessel vasculitis (LVV) at F-FDG PET/CT and to evaluate the influence of glucocorticoid (GC) therapy on these uptakes.

Methods: One hundred and one subjects with LVV and F-FDG PET/CT were included in the study. Clinical features, including blood samples and duration of GC therapy, were collected. Standardized uptake value body weight max (SUVmax) of the spleen, BM, liver and arterial walls were extracted; spleen/liver (SL) and BM/liver (BML) ratios were calculated. Chi-square and T-test were used to assess the relationship between PET/CT parameters and clinical features with the presence of LVV. Rank correlation was used to evaluate the correlation between PET/CT parameters and clinical parameters. Receiver operating curve (ROC) analysis was used to find the best parameter able to discriminate between positive and negative PET/CT. All analyses were performed considering the duration of GC therapy.

Results: Significant correlation for PET/CT results with spleen uptake (P-value = 0.001), SL (P-value < 0.001) and BML (P-value = 0.005) were reported in patients with no more than 3 days of therapy; the correlation with SL was confirmed in the total cohort of patients. A value of 0.92 for SL had an AUC of 0.959, a sensitivity of 92.6% and a specificity of 96.6% (P-value < 0.001) in predicting PET/CT results.

Conclusion: Higher splenic and BM uptake in patients with positive PET/CT for LVV were reported. A long duration of GC therapy is able to reduce such uptakes.