Impact of Inflammatory Laboratory Markers on Pancreatic 18F-Fluorodeoxyglucose Uptake during Staging 18F-Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography for Pancreatic and Periampullary Malignancies

Objective: To evaluate the relationship between laboratory markers and pancreatic ¹⁸ F-fluorodeoxyglucose (FDG) uptake on staging ¹⁸ F-FDG positron emission tomography/computed tomography (PET/CT) in patients with pancreatic or periampullary malignancies, and to clarify the interpretative implications of laboratory findings when assessing pancreatic FDG uptake. Materials and Methods: This retrospective study included 95 patients with histologically confirmed pancreatic or periampullary malignancies who underwent staging FDG PET/CT and had available laboratory data. C-reactive protein, amylase, and lipase levels were measured, and pancreatic FDG uptake was assessed using the maximum standardized uptake value and the pancreas-to-blood pool ratio (P/B ratio). The associations between laboratory markers and FDG uptake parameters were evaluated using Spearman’s and partial Spearman’s correlation analyses. Group-based comparisons were performed using the Kruskal–Wallis test with post-hoc analysis. Results: The P/B ratio differed significantly among the groups (p = 0.010), with the highest values observed in those with concurrent elevations in C-reactive protein and pancreatic enzyme levels. After adjusting for other laboratory markers, serum lipase levels remained independently associated with both the maximum standardized uptake value and P/B ratio, and C-reactive protein levels remained independently associated with P/B ratio. Representative cases showed malignant pancreatic involvement with inflammation-like FDG uptake and normal laboratory marker levels. Conclusion: Pancreatic FDG uptake was significantly influenced by inflammatory laboratory markers, particularly when assessed using the P/B ratio. Elevated serum lipase levels warrant caution when interpreting increased pancreatic FDG uptake as malignant, whereas normal laboratory markers should not be considered reassuring of benign inflammatory uptake. Integrating laboratory findings with the P/B ratio may improve the interpretation of pancreatic PET/CT findings during staging of pancreatic malignancies.