Comparative study on the diagnostic value of 18F-FDG PET/CT imaging and integrated PET/MR imaging in pediatric tumors.

Objective: To analyze and compare the diagnostic value of fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) imaging and integrated PET/magnetic resonance imaging (MR) in pediatric tumors.

Subjects and methods: A retrospective analysis was conducted on the clinical data of 61 pediatric patients with malignant tumors admitted to our hospital from September 2022 to December 2023. All patients underwent pathological examinations as well as ¹⁸F-FDG PET/CT and integrated PET/MR imaging. The pathological diagnosis results were used as the gold standard. Pearson correlation analysis, Bland-Altman analysis, and t-tests were used to compare the maximum standardized uptake value (SUVmax), signal-to-noise ratio (SNR), and target-to-background ratio (T/B) between the two methods. Chi-square tests were employed to compare the diagnostic efficacy differences of each index.

Results: Among the 61 pediatric malignant tumor patients, a total of 417 lesions were detected, of which 363 lesions showed high uptake on both PET/MR and PET/CT. Among the remaining 54 PET-negative lesions, 9 were CT-positive but MR-negative, including 6 in the lungs and 3 in the vertebrae, while 12 lesions were MR-positive but CT-negative, including 5 in the liver, 4 in the brain, and 3 in the breasts. No statistically significant difference was found in the PET positivity rate or diagnostic results between the two devices (P<0.05). Bland-Altman analysis showed that the background uptake of PET/MR images was lower than that of PET/CT, and the SNR was higher (P<0.05); the SUVmax of the lesions on PET/MR was higher than that on PET/CT (P<0.05); the T/B value of PET/MR images was higher than that of PET/CT (P<0.05). In terms of correlation, the SUVmax, SNR, and T/B values between PET/MR and PET/CT were positively correlated (r=0.919, 0.507, 0.698, P<0.05).

Conclusion: In the diagnosis of pediatric malignant tumors, PET/MR and PET/CT have relatively consistent lesion detection rates. PET/MR images have a higher SNR and better resolution, making them more advantageous than PET/CT for evaluating lesions in the liver, brain, and other soft tissue organs, thus warranting clinical application.