Effect of Diet on Physiologic Bowel ¹⁸F-FDG Uptake

Intestinal ¹⁸F-FDG uptake is variable in whole-body PET/CT. In cancer patients, particularly those suspected of relapse or metastasis, ¹⁸F-FDG absorption might interfere with scan interpretation. This study evaluated the effect of diet on intestinal ¹⁸F-FDG absorption. Methods: In total, 214 patients referring for oncologic ¹⁸F-FDG PET/CT participated. They were randomly divided into 2 groups and asked to follow either a routine diet (RD) or a low-carbohydrate, high-fat diet (LCHFD) for 24 h before the study. The small bowel and different parts of the colon (the cecum; the ascending, transverse, and descending segments; and the hepatic and splenic flexures) were evaluated and visually interpreted by nuclear medicine experts. Bowel uptake was graded through comparison with that in the liver as absent, mild, moderate, or severe. Results: Significantly higher ¹⁸F-FDG uptake in the descending colon (P = 0.001) and small intestine (P = 0.01) was observed in the RD group than in the LCHFD group. After patients with bowel cancer were omitted from the statistical analysis, no significant differences in the final results were seen. Conclusion: An LCHFD for 24 h before ¹⁸F-FDG PET imaging resulted in lower ¹⁸F-FDG uptake in the descending colon and small bowel than did an RD, assisting the interpreting physician by reducing the intestinal activity interference for more accurate diagnostic interpretation.