PET／CT显像前不同准备方法对正常Beagle犬心肌^18F—FDG生理性摄取的影响

目的探讨PET／CT显像前不同准备方法对Beagle犬心肌18F—FDG生理性摄取的影响。方法取24只健康1岁龄雄性Beagle犬，按随机数字表法分为短时间（12h）禁食加高糖（按体质量静脉注射质量分数50％葡萄糖1g／kg）（sF-Gs）组、短时间禁食（sF）组、长时间（18h）禁食（PF）组和短时间禁食加高脂餐（SF—HF）组，每组各6只犬，行18F—FDGPET／CT心肌代谢显像。图像质量分为4个等级：0级为不摄取；1级为轻度（或部分心肌）摄取；2级为心肌摄取且显像基本清晰，但不均匀；3级为心肌完全均匀摄取且显像清晰。在PET／CT融合图上选择左心室为ROI并测定SUVmax注射18F—FDG前进行血糖测定。评价心肌18F—FDG摄取程度，比较各组间心肌18F．FDG图像质量、SUVmax及血糖水平（注射显像剂前测定）间的差别。采用单因素方差分析、Kmskal．Walls秩和检验进行统计分析。结果SF—GS组心肌显像完整均匀（2级2只，3级4只），SF组心肌显像组内差异变化较大，常不均匀（2级4只，1级、3级各1只）；PF组（0级3只，1级2只，2级1只）与SF—HF组（0级4只，1级2只）心肌几乎不显影；各组间心肌18F—FDG显像质量分级差异有统计学意义（日=16．83，P〈0．01）。PF组SUVmax（3．01±0．97）与SF—HF组SUVmax（2．84±1．15）明显低于SF—GS组（14．76±4．72）与sF组（10．91±2．48）（F=69．84，P〈0．01）。PF组血糖水平（4．18±0．27）mmol／L与SF—HF组血糖水平（4．25±0．58）mmol／L也明显低于sF—Gs组（5．80±0．56）mmol／L与sF组（4．91±0．51）mmol／L（F=13．58，P〈0．01）。结论心肌18F—FDG显像前准备方法不同，显像结果也不同：sF—Gs后，犬心肌18F．FDG摄取均匀：而PF及SF．HF后。犬心肌18F—FDG牛理性摄取被抑制。

Effects of different pre-scan preparation protocols on the physiologic uptake of 18F-FDG by the myo cardium in Beagle dogs

Objective To explore the effects of different pre-scan preparation protocols on the physiologic myocardial uptake of 18F-FDG in Beagle dogs. Methods Twenty-four male Beagle dogs under went four different preparation protocols before PET/CT scans： short fasting （SF, 12 h） , SF followed by in travenous injection of glucose supplement （SF-GS） , prolonged fasting （PF, 18 h） , SF followed by high fat diet （SF-HF）, and each group included 6 Beagle dogs. The image quality based on 18F-FDG uptake in myo-cardium was assessed visually by two experienced physicians and classified into four grades： grade O, no FDG uptake ; grade 1, faint FDG uptake ; grade 2, definite FDG uptake ; grade 3, significant FDG uptake. The ROI was drawn on the myocardium of left ventricle and SUVm± was measured. The blood glucose level was measured before 18F-FDG injection. One-way analysis of variance and Kruskal-Wallis rank sum test were performed. Results In the SF-GS group, there were 2 grade 2 and 4 grade 3; while in SF group, there were 4 grade 2, 1 grade 1 and 1 grade 3. In PF group, there were 3 grade 0, 2 grade 1 and 1 grade 2; andin SF-HF group, there were 4 grade 0 and 2 grade 1 （H= 16.83, P〈0.01）. The SUVmax in PF group （3.01± 0.97） and SF-HF group （2.84±1.15） were significantly lower than those in SF-GS group （14.76±4.72） and SF group （10.91±2.48） （F= 69.84, P〈0.01 ）. The average blood glucose levels in PF group and SF- HF group were significantly lower than those in SF-GS group and SF group： （4.18±0.27） mmol/L, （4.25± 0.58） mmol/L, （5.80±0. 56） mmol/L, （4.91±0.51） mmol/L, respectively （F= 13.58, P〈0.01）. Con- elusions The 1SF-FDG uptake by myocardium was uniform under SF-GS protocol. PF and SF-HF protocols eould suppress FDG uptake by mvocardium.