title: Correlation of early-phase 18F-florbetapir (AV-45/Amyvid) PET images to FDG images: preliminary studies.
abstract: OBJECTIVE
  (18)F-Florbetapir (AV-45/Amyvid) is a novel positron emission tomography (PET) tracer for imaging plaque pathology in Alzheimer's disease (AD), while PET images of fluorodeoxyglucose (FDG) for cerebral glucose metabolism can provide complementary information to amyloid plaque images for diagnosis of AD. The goal of this preliminary study was to investigate the perfusion-like property of relative cerebral blood flow estimates (R(1)) and summed early-phase AV-45 images [perfusion AV-45 (pAV-45)] and optimize the early time frame for pAV-45.
  
  
  METHODS
  Dynamic AV-45 PET scans (0-180 min) were performed in seven subjects. pAV-45, late-phase AV-45, and FDG images were spatially normalized to the Montreal Neurological Institute template aided by individual MRI images, and the corresponding standardized uptake value ratio (SUVR) was computed. The R(1) images were derived from a simplified reference tissue model. Correlations between regional and voxelwise R(1) and the corresponding FDG images were calculated. An optimization of time frames of pAV-45 was conducted in terms of correlation to FDG images. The optimal early time frame was validated in a separate cohort.
  
  
  RESULTS
  The regional distribution in the R(1) images correlated well (R = 0.91) to that of the FDG within subjects. Consistently high correlation was noted across a long range of time frames. The maximal correlation of pAV-45 to FDG SUVR of R = 0.95 was observed at the time frame of 1-6 min, while the peak correlation of R = 0.99 happened at 0-2 min between pAV-45 and R(1). A similar result was achieved in the validation cohort.
  
  
  CONCLUSIONS
  Preliminary results showed that the distribution patterns of R(1) and pAV-45 images are highly correlated with normalized FDG images, and the initial 5-min early time frame of 1-6 min is potentially useful in providing complementary FDG-like information to the amyloid plaque density by late-phase AV-45 images.
authors.affiliation: Department of Nuclear Medicine and Molecular Imaging Center, Chang Gung Memorial Hospital, Taipei, Taiwan.
authors.forename: Ing-Tsung
authors.initials: IT
authors.lastname: Hsiao
authors.forename: Chin-Chang
authors.initials: CC
authors.lastname: Huang
authors.forename: Chia-Ju
authors.initials: CJ
authors.lastname: Hsieh
authors.forename: Wen-Chun
authors.initials: WC
authors.lastname: Hsu
authors.forename: Shiaw-Pyng
authors.initials: SP
authors.lastname: Wey
authors.forename: Tzu-Chen
authors.initials: TC
authors.lastname: Yen
authors.forename: Mei-Ping
authors.initials: MP
authors.lastname: Kung
authors.forename: Kun-Ju
authors.initials: KJ
authors.lastname: Lin
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology; D000814:Aniline Compounds; D002560:Cerebrovascular Circulation; D005026:Ethylene Glycols; D005260:Female; D019788:Fluorodeoxyglucose F18; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013997:Time Factors
chemical_list: D000814:Aniline Compounds; D005026:Ethylene Glycols; D019788:Fluorodeoxyglucose F18; C545186:florbetapir; D005947:Glucose