Effects of different pre-scan preparation protocols on the physiologic uptake of ¹⁸F-FDG by the myocardium 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 underwent four different preparation protocols before PET/CT scans: short fasting (SF, 12 h), SF followed by intravenous 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 myocardium was assessed visually by two experienced physicians and classified into four grades: grade 0, 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 SUV_max 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; and in SF-HF group, there were 4 grade 0 and 2 grade 1 (H = 16.83, P < 0.01). The SUV_max 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). Conclusions: The ¹⁸F-FDG uptake by myocardium was uniform under SF-GS protocol. PF and SF-HF protocols could suppress FDG uptake by myocardium. (authors)