Increased rates of [18F]FDG accumulation in the brain in children could lead to a lower amount of [18F]FDG reaching other organs and tumors: Is a new SUV correction factor that considers [18F]FDG uptake of the brain in children necessary?

Abstract

Objective: [¹⁸F]FDG uptake in the livers and tumors of children is lower than that of adults. The brain exhibits intense physiological [¹⁸F]FDG uptake. In childhood, the ratio of brain weight to body height and the ratio of brain weight to body weight are higher than those of adults. We hypothesized that in children, most of the [¹⁸F]FDG would be retained in the brain, resulting in less [¹⁸F]FDG activity reaching other organs and tumor tissues.

Methods: The [¹⁸F]FDG PET/CT images of 56 pediatric and 24 adult patients were evaluated retrospectively. Patients were divided into four age groups: 1) 3-7 years old, 2) 8-12 years old, 3) 13-17 years old, and 4) over 18 years old. Accumulated [¹⁸F]FDG activity in the brain, liver, and whole body (WB) was calculated using the manually drawn volumes of interest for all patients using NUKDOS software. Also, SUV normalized to total body weight (SUVbw) and SUV normalized to lean body mass (SUVlbm) of the liver were calculated using the NUKDOS software.

Results: The mean [¹⁸F]FDG accumulation ratio of brain-to-WB was significantly higher in patients aged 3-7 years and 8-12 years than in adults. Brain/WB [¹⁸F]FDG activity ratio was lower in the 13-17 age group compared to the 3-7 age group (P = .0001). The accumulated [¹⁸F]FDG activity ratio of liver-to-WB in the 3-7 age group was significantly lower than in adults when comparing the four groups (P = .0001). The mean of liver SUVbw was statistically lower in the 3-7 and 8-12 age groups than in the 13-17 and adult groups. Patients aged 3-7 years had a significantly lower mean liver SUVlbm than those in the other age groups. The mean liver SUVlbm was also significantly lower in the 8-12 years and 13-17 years age groups than in adults. There was a negative correlation between blood glucose levels and the amount of [¹⁸F]FDG in the brain. However, no statistically significant correlation existed between blood glucose and age.

Conclusion: We showed that the [¹⁸F]FDG accumulation rate was higher in the brain and lower in the liver in the children when compared to adults. Our findings suggest that increased uptake of [¹⁸F]FDG in children's brains may lead to reduced activity reaching other organs and tumor tissue. To improve diagnostic accuracy, adapted SUV correction protocols can be developed for pediatric populations, considering age-related changes in [¹⁸F]FDG uptake ratio of the brain.