Influence of blood glucose level, age and fasting period on non-pathological FDG uptake in heart and gut

Purpose: Increased, non-pathological FDG uptake in myocardium, stomach and bowel is frequently observed while performing clinical positron emission tomography (PET) studies. This "physiological" increased FDG uptake is not related to (oncological) disease and is unwanted since it may interfere with correct image reading. We evaluated the role of several patient-related factors that may have an influence on this phenomenon. Methods: One hundred and seventy-five non-diabetic patients with malignant diseases, referred to our department for routine whole-body FDG-PET, were retrospectively evaluated. Age, blood glucose levels and duration of the fasting period were recorded. FDG uptake in myocardium, bowel and stomach was visually graded. Results: Statistical analysis showed that increased FDG uptake in myocardium, bowel and stomach was not significantly correlated to blood glucose level, age or duration of fasting. Most patients who underwent repeated PET scans (92 scans in 25 patients), showed no or minor changes in uptake in bowel and stomach on the consecutive scans, while myocardial uptake was more variable. Conclusion: Age, fasting period and blood glucose levels did not influence physiological uptake. However, there seemed to be a patient- specific pattern for stomach and bowel uptake.