Comparison of the effect of positive and negative oral contrast agents on delineation and 18F-FDG uptake of gastrointestinal tract / 中华核医学杂志

ABSTRACT

Objective To compare the different effects of 1% diatrizoate meglumine,2.5% mannitol and water as oral contrasts in PET/CT scan in gastrointestinal tract delineation and 18F-fluorodeoxyglucose (FDG) uptake. Methods Sixty-one patients referred for PET/CT scan without gastrointestinal diseases were divided into three groups randomly ( random number method). One liter of 1% diatrizoate meglumine,2.5% mannitol,or water was orally taken by groups 1 (25 cases),2 (20 cases) and 3 ( 16 cases),respectively before scan. The scan was performed with GE Discovery LS PET/CT scanner in two-dimensional (2D) mode 50 min after 18F-FDG (5.55 MBq/kg) injection. Patients with abdominal lesions were excluded from this study. The degree of gastrointestinal filling and 18F-FDG uptake was evaluated by 3 nuclear medicine physicians using visual analysis according to a 4-grade classification method:none,mild,moderate,and high. Statistically analysis was performed by Kruskal-Wallis,Mann-Whitney and paired t tests.Results Both the differences of serum glucose and insulin levels were not significant before and after contrast taken in group 2. Group 2 had better gastrointestinal filling than that of group 1 and also better than group 3 except in rectum. The stomach,jejunum,ascending,and transverse colon were better filled in group 1 than in group 3. The degree of 18F-FDG uptake of group 3 was significantly higher than that of group 2 in stomach,jejunum and ileum (z= -3. 192,-3.290,-3.290,all P＜0.05),and was also significantly higher than that of group 1 (z = - 3. 603,P ＜ 0.05) in jejunum. The degree of 18 F-FDG uptake of group 3 was significantly lower than that of group 1 in ascending colon (z = - 2. 706,P ＜ 0. 05 ) and was significantly lower than that of group 1 and 2 in transverse and descending colon (z= - 3. 503,- 2.403,- 4.225,-4. 027,all P ＜0.05),and was also significantly lower than that of group 2 in rectum (z = -4. 128,P ＜0. 01 ). The maximum CT values in stomach,jejunum,ileum and ascending colon in group 1 were ( 132 ±23),(191 ±31),(313 ±47) and (374±53) HU,respectively,whose difference was significant (t = -7.088--1.781,all P ＜0. 01 ). Conclusion Oral iso-osmotic mannitol intake has better gastrointestinal filling and less physiological 18F-FDG uptake compared to diatrizoate meglumine and water.