Generation of an Age-Dependent and Harmonized 18F-FDG Brain PET Atlas Using a High-Sensitivity Short-Axial FOV PET/CT System.

A total of 97 participants passed quality control and were included for atlas construction after excluding subjects with outlier FDG uptake values from an initial cohort of 140 adults.

• 140 adults aged 20–90 years (72 males) were retrospectively enrolled and divided into seven age groups (n = 20 per group).
• All participants underwent 18F-FDG PET/CT at China-Japan Friendship Hospital between January 2022 and May 2023 using the Siemens Biograph Vision 600 scanner.
• PET scans were acquired for 4 minutes, 60 minutes after 18F-FDG injection at a dose of 4.44 MBq/kg.
• After quality control, 97 participants remained for atlas construction.

Gray/white contrast (GWC) was higher at the finer effective image resolution (5.0–6.0 mm) compared to the coarser resolution (8.0–10.0 mm) across age groups.

• In the 20–30 years age group, GWC was 2.73 at 5.0–6.0 mm resolution versus 1.76 at 8.0–10.0 mm resolution.
• Images were smoothed to emulate two resolution ranges: 5.0–6.0 mm and 8.0–10.0 mm effective image resolution (EIR).
• System EIR was measured using a Hoffman phantom.
• The higher GWC at finer resolution reflects better preservation of gray-white matter differentiation.

SUVRs in cortical and subcortical regions negatively correlated with age, indicating declining regional FDG uptake with increasing age.

• Age correlations with SUVR were found in cortical and subcortical regions across both resolution ranges.
• Brainstem SUVRs showed age correlation only at the lower resolution (8.0–10.0 mm) and not at the higher resolution (5.0–6.0 mm).
• SUVRs were calculated using the whole cerebellum as the reference region.
• Images were normalized to MNI space at 1.0 mm isotropic resolution via ANTs registration.

SUVRs were systematically higher at higher image resolution (5.0–6.0 mm) compared to lower resolution (8.0–10.0 mm) across all brain regions examined.

• SUVR differences between the two EIR conditions were observed across cortical, subcortical, and brainstem regions.
• The difference in SUVRs between resolution levels is attributable to partial volume effects being more pronounced at lower spatial resolution.
• This finding underscores the importance of EIR-harmonized atlases when comparing data across different PET scanners.

Age-stratified and EIR-harmonized FDG brain PET atlases were successfully generated for seven age groups spanning 20–90 years at two effective image resolution ranges.

• Seven age groups were defined (20–30, 30–40, 40–50, 50–60, 60–70, 70–80, 80–90 years), each originally containing n = 20 participants.
• Atlases were created for both 5.0–6.0 mm and 8.0–10.0 mm EIR ranges to support diverse PET/CT scanner types.
• The atlases were constructed at 1.0 mm isotropic resolution in MNI standard space.
• The study aimed to reduce misinterpretation and quantification errors arising from mismatched atlases across different scanner technologies.