Standardized quantification of [18F]Florbetazine amyloid PET with the Centiloid scale.

UNLABELLED: [18F]Florbetazine ([18F]FBZ) is a novel Aβ tracer with imaging characteristics similar to [11C]PiB. This study aimed to establish Centiloid conversion equations for [18F]FBZ and to evaluate its quantification precision relative to [11C]PiB across different image-processing pipelines and effective image resolutions (EIRs). METHODS: Paired [11C]PiB and [18F]FBZ PET scans were acquired in 53 participants. Centiloid conversion equations for [18F]FBZ standardized uptake value ratio (SUVR), derived from both the standard SPM pipeline and a FreeSurfer pipeline, were calculated following the Level-2 analysis proposed by Klunk et al. The variance ratio of Centiloids derived from [18F]FBZ SUVR to those derived from standard [11C]PiB SUVR in YCs was computed to compare quantification precision. Additionally, the linear relationships between [18F]FBZ and [11C]PiB SUVR were evaluated under different EIRs. RESULTS: The Centiloid conversion equation for [18F]FBZ SUVR using the standard SPM pipeline was: Centiloid=98.6 × [18F]FBZ SUVRstd-99.8 (variance ratio=0.92). For the FreeSurfer pipeline, the conversion was: Centiloid=110.1 × [18F]FBZ SUVRfs-108.1 (variance ratio=0.55). Robust linear correlations between [11C]PiB and [18F]FBZ SUVR were observed across EIRs with the SPM pipeline, whereas regression parameters varied across EIRs with the FreeSurfer pipeline. CONCLUSION: [18F]Florbetazine SUVR can be reliably converted to Centiloid units. Compared with [11C]PiB, [18F]FBZ demonstrated equal or improved quantification precision, supporting its broader use in clinical and research Aβ imaging.