Regional differences in 18F-flutemetamol accumulation between amyloid-positive and -negative brains using high-resolution dedicated head PET scanner.

OBJECTIVE: To investigate regional 18F-flutemetamol accumulation differences between amyloid-positive (Aβ⁺) and amyloid-negative (Aβ⁻) brains, particularly in cerebral white matter, using a dedicated head PET (dhPET) scanner. METHODS: This retrospective study included 38 consecutive participants who underwent ¹⁸F-flutemetamol PET using a high-resolution dhPET scanner (SET-5002, Shimadzu). Participants were classified as Aβ⁺ or Aβ⁻ based on cortical uptake patterns. Voxels of interest were anatomically defined using OpenMAP-T1, an MRI-based automated brain parcellation software, and merged into 33 regions for SUVR calculation. SUVRs were calculated using the Centiloid whole cerebellar VOIs as the reference region. Group comparisons were assessed using two-way repeated-measures ANOVA, followed by Mann-Whitney U tests with false discovery rate correction. Age and MMSE were compared using nonparametric tests, and gender using Fisher's exact test. RESULTS: The Aβ⁺ (n = 25) and Aβ⁻ (n = 13) groups did not differ in age, gender, or MMSE. ANOVA revealed significant effects of group, VOI, and group×VOI interaction (all p < 0.001). After FDR correction, SUVRs were significantly higher in the Aβ⁺ group across widespread cortical gray matter, cerebral white matter, and subcortical structures, as well as in the choroid plexus and cerebellar gray matter (all q < 0.05). No significant differences were observed in cerebellar white matter, cerebellar peduncle, or brainstem regions. CONCLUSION: High-resolution dhPET revealed significantly higher SUVRs in Aβ⁺ compared with Aβ⁻ subjects in supratentorial structures, including cerebral white matter, and in cerebellar gray matter.