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

[ 18 F]Florbetazine ([ 18 F]FBZ) is a novel Aβ tracer with imaging characteristics similar to [ 11 C]PiB. This study aimed to establish Centiloid conversion equations for [ 18 F]FBZ and to evaluate its quantification precision relative to [ 11 C]PiB across different image-processing pipelines and effective image resolutions (EIRs). Methods Paired [ 11 C]PiB and [ 18 F]FBZ PET scans were acquired in 53 participants. Centiloid conversion equations for [ 18 F]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 [ 18 F]FBZ SUVR to those derived from standard [ 11 C]PiB SUVR in YCs was computed to compare quantification precision. Additionally, the linear relationships between [ 18 F]FBZ and [ 11 C]PiB SUVR were evaluated under different EIRs. Results The Centiloid conversion equation for [ 18 F]FBZ SUVR using the standard SPM pipeline was: Centiloid=98.6 × [ 18 F]FBZ SUVR std –99.8 (variance ratio=0.92). For the FreeSurfer pipeline, the conversion was: Centiloid=110.1 × [ 18 F]FBZ SUVR fs –108.1 (variance ratio=0.55). Robust linear correlations between [ 11 C]PiB and [ 18 F]FBZ SUVR were observed across EIRs with the SPM pipeline, whereas regression parameters varied across EIRs with the FreeSurfer pipeline. Conclusion [ 18 F]Florbetazine SUVR can be reliably converted to Centiloid units. Compared with [ 11 C]PiB, [ 18 F]FBZ demonstrated equal or improved quantification precision, supporting its broader use in clinical and research Aβ imaging.