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Updated: Sep 19, 2025
Whole-body PET/MRI of Pediatric Patients: The Details That Matter
Published on: December 19, 2017
Assessment of reduced 18F-FDG dosage in pediatric PET/MR imaging through randomized down-sampling
Xiaoyue Tan1, Yongrong Zhou1, Qing Zhang1
1PET Center, Department of Nuclear Medicine, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, 106 Zhongshan Er Road, Guangzhou, 510080, China.
Insights
Reduced 18F-FDG dosage is feasible in pediatric PET/MR imaging. Clinically acceptable image quality was achieved with a low dose of 0.74 MBq/kg, enabling identification of FDG-avid lesions.
Area of Science:
- Medical Imaging
- Nuclear Medicine
- Radiochemistry
Background:
- 18F-FDG PET/MR imaging is crucial for pediatric diagnostics.
- Optimizing radiotracer dosage is essential to minimize radiation exposure in children.
- Previous studies have explored dose reduction in adult PET imaging, but pediatric data is limited.
Purpose of the Study:
- To evaluate the feasibility of reducing 18F-FDG dosage in pediatric PET/MR imaging.
- To assess the impact of dose reduction on image quality and lesion detectability.
- To determine the lowest effective 18F-FDG dose for pediatric PET/MR examinations.
Main Methods:
- Retrospective analysis of 44 pediatric patients (age range 1-17 years) who underwent 18F-FDG PET/MR.
- Simulated dose reduction to 1/2, 1/3, 1/4, 1/10, and 1/20 of the full dose (2.96 MBq/kg) using random down-sampling.
- Subjective visual assessment of image quality and quantitative analysis of lesions and background uptake compared to the full-dose reference.
Main Results:
- Subjective image quality was clinically acceptable (score ≥ 3) for 1/2, 1/3, and 1/4 dose groups.
- All FDG-avid lesions were identifiable in the 1/2, 1/3, and 1/4 dose groups, similar to the full-dose group.
- While blood pool and liver SUVmax/SD increased with dose reduction, SUVmean remained comparable. Significant differences in lesion SUVmax/SD and lesion-to-background ratio were noted for doses 1/2-1/20 compared to full dose (p < 0.05).
Conclusions:
- Reduced 18F-FDG activities are feasible for pediatric PET/MR scans.
- A low dose of 0.74 MBq/kg can achieve clinically acceptable image quality.
- This dose reduction strategy may minimize radiation exposure in pediatric patients without compromising diagnostic accuracy.
Purpose:
This study aimed to explore the feasibility of reduced 18F-FDG dosage in pediatric PET/MR imaging through randomized down-sampling.
Methods:
Forty-four pediatric patients (26 males, 18 females; median: 11 years [range, 1-17]) underwent 18F-FDG PET/MR examinations were retrospectively enrolled. PET data were reconstructed into 6 groups with different simulated doses using randomly down-sampling: full dose (2.96 MBq/kg), 1/2 dose, 1/3 dose, 1/4 dose, 1/10 dose, and 1/20 dose. Subjective visual analysis of image quality was evaluated using a 5-point Likert scale. Quantitative parameters of lesions and blood pool and liver background were analyzed. The full dose group was served as a reference.
Results:
Subjective image quality of 1/2 dose, 1/3 dose and 1/4 dose images was clinically acceptable (score ≥ 3), and all FDG-avid lesions could be identified in these three groups like full-dose group. SUVmax and standard deviation (SD) of blood pool and liver increased as the dose reduced, while no significant difference in SUVmean of blood pool and liver was found in 1/2-1/20 dose groups when compared to the full dose group. Besides, a significant difference was observed in SUVmax and SD of lesion and lesion-to-background ratio between 1/2-1/20 dose and full dose groups (p < 0.05).
Conclusion:
Further reduction in administered 18F-FDG activities is feasible in pediatric PET/MR scan. Clinically acceptable image quality could be achieved using a low dose of 0.74 MBq/kg.
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