Visual assessment versus quantitative assessment of 11C-PIB PET and 18F-FDG PET for detection of Alzheimer's disease

Steven Ng, Victor L. Villemagne, Sam Berlangieri, Sze Ting Lee, Martin Cherk, Sylvia J. Gong, Uwe Ackermann, Tim Saunder, Henri Tochon-Danguy, Gareth Jones, Clare Smith, Graeme O'Keefe, Colin L. Masters, Christopher C. Rowe

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Abstract

Amyloid-β (Aβ) imaging with N-methyl-11C-2-(4′- methylaminophenyl)-6-hydroxy-benzothiazole (11C-6-OH-BTA-1; also known as 11C-PIB) shows a robust increase in cortical binding in Alzheimer's disease (AD). The aim of this study was to explore the clinical potential of Aβ imaging for the diagnosis of AD by comparison of the accuracy of visual reading of 11C-PIB images with quantitative analysis and 18F-FDG. Methods: Fifteen AD patients (age, 71.1 ± 11.3 y [mean 6 SD]; mini-mental state examination [MMSE], 18.9 ± 9.3 [mean ± SD]) and 25 healthy control (HC) subjects (age, 71.9 ± 6.82 y; MMSE ≥ 28) underwent 90-min dynamic 11C-PIB PET and 20-min static 18F-FDG PET. 11C-PIB images, generated from data acquired between 40 and 70 min after injection, and 18F-FDG images were rated separately by 2 readers as normal, possible AD, or probable AD. Quantitative analyses used the distribution volume ratio (DVR) of frontal cortex, parietotemporal cortex, posterior cingulate, and caudate nucleus for 11C-PIB and standardized uptake value ratio (SUVR) of parietotemporal cortex and posterior cingulate for 18F-FDG, using cerebellar cortex as the reference region. Receiver-operating-characteristic (ROC) analysis was performed to compare the accuracy of quantitative measures. To determine the effect of age on diagnostic accuracy, the median age of the AD subjects (74 y) was chosen to separate the cohort into younger (64.4 ± 5.8 y) and older (78.6 ± 4.1 y) groups. Results: Visual agreement between readers was excellent for 11C-PIB (κ = 0.90) and good for 18F-FDG (κ = 0.56). 11C-PIB was more accurate than 18F-FDG both on visual reading (accuracy, 90% vs. 70%, P = 0.05) and ROC analysis (95% vs. 83%, P = 0.02). Accuracy declined more with 18F-FDG than with 11C-PIB in the older group. Conclusion: Visual analysis of 11C-PIB images appears more accurate than visual reading of 18F-FDG for identification of AD and has accuracy similar to quantitative analysis of a 90-min dynamic scan. The accuracy of 11C-PIB PET is limited by cortical binding in some healthy elderly subjects, consistent with postmortem studies of cerebral Aβ. Longitudinal follow-up is required to determine if this represents detection of preclinical AD.

Original languageEnglish
Pages (from-to)547-552
Number of pages6
JournalJournal of Nuclear Medicine
Volume48
Issue number4
DOIs
Publication statusPublished - 1 Apr 2007
Externally publishedYes

Keywords

  • C-PIB
  • F-FDG
  • Alzheimer's disease
  • Amyloid-β
  • Brain imaging
  • PET

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