title: Regional Fluid-Attenuated Inversion Recovery (FLAIR) at 7 Tesla correlates with amyloid beta in hippocampus and brainstem of cognitively normal elderly subjects.
abstract: BACKGROUND
  Accumulation of amyloid beta (Aβ) may occur during healthy aging and is a risk factor for Alzheimer Disease (AD). While individual Aβ-accumulation can be measured non-invasively using Pittsburgh Compund-B positron emission tomography (PiB-PET), Fluid-attenuated inversion recovery (FLAIR) is a Magnetic Resonance Imaging (MRI) sequence, capable of indicating heterogeneous age-related brain pathologies associated with tissue-edema. In the current study cognitively normal elderly subjects were investigated for regional correlation of PiB- and FLAIR intensity.
  
  
  METHODS
  Fourteen healthy elderly subjects without known history of cognitive impairment received 11C-PiB-PET for estimation of regional Aβ-load. In addition, whole brain T1-MPRAGE and FLAIR-MRI sequences were acquired at high field strength of 7 Tesla (7T). Volume-normalized intensities of brain regions were assessed by applying an automated subcortical segmentation algorithm for spatial definition of brain structures. Statistical dependence between FLAIR- and PiB-PET intensities was tested using Spearman's rank correlation coefficient (rho), followed by Holm-Bonferroni correction for multiple testing.
  
  
  RESULTS
  Neuropsychological testing revealed normal cognitive performance levels in all participants. Mean regional PiB-PET and FLAIR intensities were normally distributed and independent. Significant correlation between volume-normalized PiB-PET signals and FLAIR intensities resulted for Hippocampus (right: rho = 0.86; left: rho = 0.84), Brainstem (rho = 0.85) and left Basal Ganglia vessel region (rho = 0.82).
  
  
  CONCLUSIONS
  Our finding of a significant relationship between PiB- and FLAIR intensity mainly observable in the Hippocampus and Brainstem, indicates regional Aβ associated tissue-edema in cognitively normal elderly subjects. Further studies including clinical populations are necessary to clarify the relevance of our findings for estimating individual risk for age-related neurodegenerative processes such as AD.
authors.affiliation: Division of Psychiatry Research and Psychogeriatric Medicine, University of Zürich Zürich, Switzerland.
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Schreiner
authors.affiliation: Department of Radiology, Harvard Medical School, Brigham and Women's Hospital Boston, MA, USA.
authors.forename: Xinyang
authors.initials: X
authors.lastname: Liu
authors.affiliation: Division of Psychiatry Research and Psychogeriatric Medicine, University of Zürich Zürich, Switzerland.
authors.forename: Anton F
authors.initials: AF
authors.lastname: Gietl
authors.affiliation: Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, University of Zürich and ETH Zürich Zürich, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Wyss
authors.affiliation: Division of Psychiatry Research and Psychogeriatric Medicine, University of Zürich Zürich, Switzerland.
authors.forename: Stefanie C
authors.initials: SC
authors.lastname: Steininger
authors.affiliation: Division of Psychiatry Research and Psychogeriatric Medicine, University of Zürich Zürich, Switzerland.
authors.forename: Esmeralda
authors.initials: E
authors.lastname: Gruber
authors.affiliation: Division of Psychiatry Research and Psychogeriatric Medicine, University of Zürich Zürich, Switzerland ; Division of Nuclear Medicine, University of Zürich Zürich, Switzerland.
authors.forename: Valerie
authors.initials: V
authors.lastname: Treyer
authors.affiliation: Division of Psychiatry Research and Psychogeriatric Medicine, University of Zürich Zürich, Switzerland ; Taub Institute for Research on Alzheimer's Disease and the Aging Brain, College of Physicians and Surgeons, Columbia University Medical Center New York, NY, USA.
authors.forename: Irene B
authors.initials: IB
authors.lastname: Meier
authors.affiliation: Division of Psychiatry Research and Psychogeriatric Medicine, University of Zürich Zürich, Switzerland.
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Kälin
authors.affiliation: Division of Psychiatry Research and Psychogeriatric Medicine, University of Zürich Zürich, Switzerland.
authors.forename: Sandra E
authors.initials: SE
authors.lastname: Leh
authors.affiliation: Division of Nuclear Medicine, University of Zürich Zürich, Switzerland.
authors.forename: Alfred
authors.initials: A
authors.lastname: Buck
authors.affiliation: Division of Psychiatry Research and Psychogeriatric Medicine, University of Zürich Zürich, Switzerland.
authors.forename: Roger M
authors.initials: RM
authors.lastname: Nitsch
authors.affiliation: Department of Information Technology and Electrical Engineering, Institute for Biomedical Engineering, University of Zürich and ETH Zürich Zürich, Switzerland.
authors.forename: Klaas P
authors.initials: KP
authors.lastname: Pruessmann
authors.affiliation: Division of Psychiatry Research and Psychogeriatric Medicine, University of Zürich Zürich, Switzerland.
authors.forename: Christoph
authors.initials: C
authors.lastname: Hock
authors.affiliation: Division of Psychiatry Research and Psychogeriatric Medicine, University of Zürich Zürich, Switzerland.
authors.forename: Paul G
authors.initials: PG
authors.lastname: Unschuld
keywords: 7 Tesla; FLAIR; MRI; PiB-PET; aging; amyloid beta