The effects of hypotonic and isotonic negative contrast agent on gastrointestinal distention and physiological intake of 18F-FDG.

OBJECTIVE: The objective of this study was to explore the effects of hypotonic and isotonic oral mannitol on intestinal distention and fluorine-18 fluorodeoxyglucose ((18)F-FDG) intake in PET/computed tomography (CT) imaging. MATERIALS AND METHODS: A total of 124 patients without gastrointestinal disease were evaluated with PET/CT imaging and divided into four groups using a random number table. Group 1 drank plain water, group 2 drank 2.5% mannitol, group 3 drank 2.5% mannitol and also received 10 mg of scopolamine butylbromide, and group 4 drank 2.5% mannitol and also received 20 mg of scopolamine butylbromide. The patients in each group underwent PET/CT imaging 50 min after (18)F-FDG injection. In these groups, differences such as age, sex, disease distribution, oral liquid amount, and adverse reactions were compared. Gastrointestinal distention and F-FDG intake were analyzed by two experts in nuclear medicine by visual observation. Data were statistically analyzed using a rank-sum test, R×C contingency table, one-way analysis of variance, and a paired t-test. RESULTS: There were no significant differences in blood glucose levels after oral administration of 2.5% mannitol (t=0.62, P>0.05). Gastrointestinal distention of patients in groups 2, 3, and 4 was superior to that of patients in group 1 (P<0.05/6). In addition to the sigmoid colon and rectum, (18)F-FDG intake in each part of the gastrointestinal tract in groups 2, 3, and 4 was less than that in group 1 (P<0.05/6). Patients in group 4 experienced significantly more adverse reactions compared with patients in the other groups (P<0.05). CONCLUSION: Oral negative contrast agent and hypotonic bowel preparation decreased the physiological intake of (18)F-FDG, increased the distention of the gastrointestinal tract, and thus improved the image quality.