口服不同对比剂对PET／CT胃肠道充盈及FDG摄取影响

目的 比较PET／CT显像前口服泛影葡胺、甘露醇和清水对胃肠道显示和脱氧葡萄糖（FDG）摄取的差异。方法将61例无胃肠道疾病行PET／CT显像的患者按随机数字法分成3组，组1（25例）显像前口服质量分数1％泛影葡胺1L；组2（20例）显像前口服质量分数2．5％甘露醇1L；组3（16例）显像前口服清水1L。患者注射18F—FDG（按体质量5．55MBq/kg）后50min应用二维（2D）模式进行PET／CT显像。由3位核医学科医师分别应用目测分析法将胃肠道充盈状态和FDG摄取情况分为4类：无、轻度、中度和重度。应用秩和检验、配对t检验对相关数据进行统计学分析。结果组2患者口服甘露醇前后血糖和血胰岛素水平差异无统计学意义。组2患者胃肠道充盈好于组1；除直肠外，其余部位充盈状态好于组3。组1患者胃、空肠、升结肠和横结肠充盈状态好于组3患者。组3患者胃、空肠和回肠FDG摄取程度高于组2患者（z=-3．192，-3．290，-3．290，P〈0．05）；空肠FDG摄取高于组1（z=-3．603，P〈0．05），升结肠FDG摄取低于组1（z=-2．706，P〈0．05），横结肠和降结肠FDG摄取均明显低于其他2组（Z=-3．503，-2．403，-4．223，-4．027，P〈0．05），直肠FDG摄取明显低于组2（Z=-4．128，P〈0．01）。组1患者胃、空肠、回肠和升结肠最大CT值分别为（132±23），（191±31），（313±47）和（374±53）HU，差异有统计学意义（t=-7．088～-1．781，P〈0．01）。结论口服甘露醇作为增强剂胃肠道充盈好，FDG生理性摄取相对较低。

Comparison of the effect of positive and negative oral contrast agents on delineation and 18F-FDG uptake of gastrointestinal tract

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.