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Objective:Detection/localization of infection and inflammation is important for the initiation of correct treatment as well as its maintenance. Nuclear medicine imaging methods play an important role in determining infection and inflammation. 18F-2’-deoxy-2-fluoro-d-glucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) is highly sensitive in such cases when used with tomographic cross-sections. In this study, the development and progression of infection and inflammation were monitored on rats by using 18F-FDG via PET/CT.Methods:Sterile and infected abscesses were formed on rats using turpentine and S. aureus, respectively. For evaluation of the formation and progression of the abscess, 18F-FDG was injected into the rats and they were imaged by PET/CT at intervals of twenty-four hours for five days. Maximum standard uptake value (SUVmax) of 18F-FDG was calculated.Results:The highest activity involvement was seen on the first day of abscess formation. On the first day, SUVmax of the S. aureus abscess was 3.9±0.9 while in the sterile abscess SUVmax in the first day was 2.2±0.8. 18F-FDG uptake decreased day by day and it reached the background level on the fourth and fifth days. There were statistically significant differences between S. aureus and sterile abscess, and between sterile abscess and background activity in terms of SUVmax values during the first three days (p<0.05). On the fourth and fifth days, there was no statistically significant difference between S. aureus and sterile abscess, and between sterile abscess and background activity (p>0.05).Conclusion:The results demonstrated that the SUVmax value for 18F-FDG can be useful in the early differentiation of sterile and infected abscess. In addition, 18F-FDG-PET imaging has the advantage of local availability of equipment and labeled agents leading rapid diagnosis of differentiation of infection and inflammation.

Lung uptake of intravenously injected Tc-99m-HMPAO is observed in smokers and in lung toxicity due to various agents. We investigated the Tc-99m-HMPAO uptake of bronchoalveolar lavage (BAL) cells in the lungs after incubation in in vitro conditions (6 patients), intravenous injection (IV) (7 patients) and inhalation (INH) (6 patients) of Tc-99m-HMPAO in order to show whether BAL cells are also responsible for Tc-99m-HMPAO uptake in the lungs. Cell/supernatant (C/S) count ratio was 7.0 +/- 3.5, 29.3 +/- 40.8 and 8.4 +/- 4.5 for in vitro, IV and INH groups, respectively. C/Sin vitro showed a positive correlation with % alveolar macrophages (r = 0.943, p = 0.0048) and a negative correlation with % neutrophils (r = -0.945, p = 0.0045). Cells/whole BAL fluid ratio correlated with the amount of daily cigarette consumption in INH group (r = 0.95, p = 0.0037). Tc-99m-HMPAO showed adherence to mucus after inhalation. Tc-99m-HMPAO diffuses into alveolar spaces after injection and is present in BAL fluid and BAL cells both after injection and inhalation. Glutathione concentration and oxido-reductive state of the epithelial lining fluid and BAL cells may influence the lung uptake of Tc-99m-HMPAO.

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