Impact of half-dose 18F-FDG on the image quality of total-body PET/CT in infants and toddlers / 中华核医学与分子影像杂志

ABSTRACT

Objective:To explore the impact of half-dose 18F-FDG on the image quality in infants and toddlers undergoing total-body PET/CT. Methods:From January 2021 to August 2023, 59 infants and toddlers undergoing total-body 18F-FDG PET/CT scans at Sun Yat-Sen University Cancer Center were retrospectively enrolled. Of these, 21 patients (11 males, 10 females; age: 22.0(7.5, 34.5) months) were given a full dose of 18F-FDG (3.70 MBq/kg), and the other 38 patients (24 males, 14 females; age: 20.0(9.3, 33.3) months) received half dosage (1.85 MBq/kg) both with 10-minute scans. The differences of image quality scores and quantitative parameters including SUV, standard deviation (SD) of SUV, signal-to-noise ratio (SNR), and the normalized SNR for administered activity and scan time (SNR norm) were compared between the two groups by Mann-Whitney U test. The correlations between age, body weight and image quality were analyzed by Spearman rank correlation analysis. Results:The injected dosage of 18F-FDG for the full-dose group was 46.99(27.75, 50.42) MBq, while for the half-dose group was 21.83(18.13, 28.86) MBq. Compared to the full-dose group, the half-dose group had higher SD in the mediastinal blood pool (0.04(0.03, 0.05) vs 0.05(0.04, 0.08); z=-2.32, P=0.021). No statistically significant differences were observed between the two groups in terms of other SUV parameters ( z values: from -1.92 to -0.48, all P>0.05). In terms of image quality, the liver SNR of full-dose group was 29.5(25.3, 39.9), while that of half-dose group was 25.8(22.0, 30.4), with no significant difference ( z=1.66, P=0.096). The SNR values of mediastinal blood pool showed the same comparing result (20.0(11.4, 31.0) vs 19.0(11.4, 31.0); z=0.02, P=0.981). The correlation analysis revealed that SNR norm decreased with increasing age and body weight ( rs values: -0.704, -0.647, both P<0.001). Conclusions:In infants and toddlers, half-dose 18F-FDG total-body PET/CT with 10-minute scan can still achieve good performance. There is an observed decline in image quality with increasing age and body weight.