Correlations between glucose metabolism of bone marrow on (18)F-fluoro-D-glucose PET/computed tomography and hematopoietic cell populations in autoimmune diseases

This study aims to investigate which hematopoieticcell populations, clinical factors, and laboratory values are associated with FDG uptake in bone marrow (BM) on FDG PET/CT in patients with autoimmune diseases. METHODS: Forty-six patients with autoimmune disease who underwent FDG PET/CT and BM aspiration (BMA) between 2017 and 2022 were enrolled. The max and mean standard uptake values (SUVmax and SUVmean, SUVs) of FDG in BM, liver, and spleen were measured, and the bone marrow-to-liver SUVs ratios (BLRmax and BLRmean, BLRs) and spleen-to-liver SUVs ratios (SLRmax and SLRmean, SLRs) were calculated. BMA and clinical and laboratory parameters were collected and evaluated for association with BLRs and SLRs. RESULTS: The patients were divided into the Grade II group (20; 43.5%) and Grade III groups (26; 56.5%) according to hemopoietic activity. The BLRmax (P = 0.021), proportion of granulocytes (P = 0.011), metamyelocytes (P = 0.009), myelocytes (P = 0.024), and monocytes (P = 0.037) in BM were significantly higher in the Grade II group. Multivariate (stepwise) linear regression analyses showed that the proportion of granulocytes in BM was the strongest and only independent factor (P < 0.0001) associated with BLRmax with an adjusted R(2) of 0.431 in model 1. In model 2, ferritin (P = 0.018), CRP (P = 0.025), and the proportion of metamyelocytes (P = 0.043) in BM were correlated with BLRmax with an adjusted R(2) of 0.414. CONCLUSION: The FDG uptake in BM is associated with hemopoietic activity and is regulated by hyperplastic granulocytes, particularly immature metamyelocytes, in patients with autoimmune diseases. Glucose metabolism in the BM correlates with the severity of systemic inflammation.