Impact of fasting on ¹⁸F-fluorocholine gastrointestinal uptake and detection of lymph node metastases in patients with prostate cancer

Background: 18F-fluorocholine PET/CT is used to detect lymph node metastases in prostate cancer patients. Physiological 18F-fluorocholine in the gastrointestinal tract, especially in the intestines, may interfere with the detection of malignant lymph nodes. Fasting is frequently proposed in literature; however, scientific support is lacking. This study aims to determine the impact of fasting on 18F-fluorocholine uptake in the gastrointestinal tract. Methods: Eighty patients were studied, 40 fasted for at least 6 h prior to 18F-fluorocholine administration while the other 40 did not fast. 18F-fluorocholine uptake pattern and intensity were evaluated in the intestine near the abdominal aorta and four regions near the iliac arteries. 18F-fluorocholine intensity was also measured in the liver, pancreas, stomach and spleen. Findings: No statistically significant differences were found in 18F-fluorocholine uptake in the gastrointestinal tract between the fasting and non-fasting group. Conclusions: Fasting for 6 h has no effect on 18F-fluorocholine uptake in the gastrointestinal tract. Therefore, no effects on the detection of malignant lymph nodes are expected, and fasting is not recommended in our opinion.