Bone marrow 18F-fluorodeoxyglucose uptake may be a significant finding to evaluate the systemic inflammatory condition.

1743 Objectives Systemic Inflammatory Response Syndrome (SIRS) criteria were currently the important implication to evaluate inflammatory condition. Number of studies showed the patients who matched the more SIRS criteria presented the poorer prognosis. However, those values possibly fluctuate affected by treatment, evaluate situation, or timing.\n18F-fluorodeoxyglucose (FDG) PET/CT is an established tool to evaluate not only malignant tumors but also infectious diseases. During clinical investigations for infectious diseases, not a few patients showed diffuse higher bone marrow uptake than liver uptake. We hypothesized that diffuse bone marrow uptake may reflect severity of systemic infectious condition. Bone marrow can be activated by hormonal factors like inflammatory cytokine under the conditions of severe infection and result in diffusely elevated accumulation of FDG. However, the significance of bone marrow uptake of FDG was not fully known. Therefore, this study analysed the correlation between inflammatory condition and bone marrow FDG uptake. Methods This study investigated 37 patients who underwent FDG PET/CT to evaluate the infectious disease. All of the patients were confirmed to have infectious disease based on final diagnosis (infection-positive group). The control group consisted of 31 patients who underwent FDG PET/CT for the purpose of detecting cancer recurrence but showed no evidence of recurrence. The control group patients had not received any treatments for malignant tumor for \u003e1 year. Before FDG PET/CT, all patients fasted more than 6 hours. The emission scanning was initiated 60 min after completion of intravenous injections of FDG (4.5 MBq/kg). The bone marrow to blood ratio (BBratio) represented the value of bone marrow FDG uptake which normalized by blood pool uptake in descending aorta. Patients’ general conditions were estimated by SIRS criteria. That was the important prognostic implication of the patients with infectious diseases. The evaluated values of SIRS as infectious conditions in this study were described below table. All of the values were evaluated ≤3 days before or after FDG PET/CT scanning. Three (8.1%) patients had 3, 13 (35.1%) patients had 2, 9 (24.3%) patients had 1, and 12 (32.4%) patients had zero SIRS values. Results The BBratio was significantly higher in infection-positive group than in control group (1.17±0.24 vs. 0.88±0.19, p\u003c0.001, Fig. 1). In the infection-positive group (N=37), BBratio was significantly higher in patients satisfying more number of SIRS criteria (1.01±0.10 vs. 1.19±0.19 vs. 1.28±0.27 for zero vs. 1 vs. 蠅2 SIRS criteria, p\u003c0.01, Fig. 2). For the infection-positive patients, the ROC analysis demonstrated the clinical utility of the BBratio to separate positive from negative SIRS criteria with area under the curve of 0.88 (Fig. 3). When the threshold of BBratio was settled on 1.00, the sensitivity, specificity, and accuracy to detect the patients who met SIRS criteria were 91. 7 %, 70. 5%, 77.9%, respectively.\nIn infection positive group, 6 cases underwent FDG PET/CT on post-treatment, too. 5/6 (83.3%) cases presented decrease of BBratio, of which 2 had been free from infectious condition, and 3showed decrease of infectious activity. 1/6 case which BBratio was increase, died in follow up period. Conclusions Increased bone marrow uptake of FDG was significantly correlated with positive SIRS criteria in infection-positive group. High BBratio may reflect severity of systemic infectious condition, and may have a strong potential as objective finding to evaluate the systemic inflammatory condition. Furthermore, follow up PET/CT revealed that the cases with decrease of BBratio presented good prognosis. BBratio may contribute to evaluate treatment effects and could suggest more beneficial information to select the treatment strategies.\n$$graphic_05135DFA-5EB7-4B56-B0AE-6A58F6A76EFC$$\n$$graphic_11099D31-0F53-4E42-B568-7A4238079158$$\n$$graphic_6C111AB6-BEA6-4BE1-88DB-8A119DEA3920$$