title: Discriminative Power of Arterial Spin Labeling Magnetic Resonance Imaging and 18F-Fluorodeoxyglucose Positron Emission Tomography Changes for Amyloid-β-Positive Subjects in the Alzheimer's Disease Continuum.
abstract: BACKGROUND
  Recent studies have demonstrated that arterial spin labeling magnetic resonance imaging (ASL-MRI) and fluorodeoxyglucose positron emission tomography (FDG-PET) identify similar regional abnormalities and have comparable diagnostic accuracy in Alzheimer's disease (AD). The agreement between these modalities in the AD continuum, which is an important concept for early detection and disease monitoring, is yet unclear.
  
  
  OBJECTIVE
  We aimed to assess the ability of the cerebral blood flow (CBF) measures from ASL-MRI and cerebral metabolic rate for glucose (CMRgl) measures from FDG-PET to distinguish amyloid-β-positive (Aβ+) subjects in the AD continuum from healthy controls.
  
  
  METHODS
  The study included asymptomatic, cognitively normal (CN) controls and patients with early mild cognitive impairment (MCI), late MCI, and AD, all with significant levels of cortical Aβ based on their florbetapir PET scans to restrict the study to patients truly in the AD continuum. The discrimination power of each modality was based on the whole-brain patterns of CBF and CMRgl changes identified by partial least squares logistic regression, a multivariate analysis technique.
  
  
  RESULTS
  While CBF changes in the posterior inferior aspects of the brain and a pattern of CMRgl changes in the superior aspects of the brain including frontal and parietal regions best discriminated the Aβ+ subjects in the early disease stages from the Aβ- CN subjects, there was a greater agreement in the whole-brain patterns of CBF and CMRgl changes that best discriminated the Aβ+ subjects from the Aβ- CN subjects in the later disease stages. Despite the differences in the whole-brain patterns of CBF and CMRgl changes, the discriminative powers of both modalities were similar with statistically nonsignificant performance differences in sensitivity and specificity.
  
  
  CONCLUSIONS
  The results comparing measurements of CBF to CMRgl add to previous reports that MRI-measured CBF has a similar diagnostic ability to detect AD as has FDG-PET. Our findings that CBF and CMRgl changes occur in different brain regions in Aβ+ subjects across the AD continuum compared with Aβ- CN subjects may be the result of methodological differences. Alternatively, these findings may signal alterations in neurovascular coupling which alter relationships between brain perfusion and glucose metabolism in the AD continuum.
authors.forename: Duygu
authors.initials: D
authors.lastname: Tosun
authors.forename: Norbert
authors.initials: N
authors.lastname: Schuff
authors.forename: William
authors.initials: W
authors.lastname: Jagust
authors.forename: Michael W
authors.initials: MW
authors.lastname: Weiner
mesh_terms: D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D001921:Brain / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D060825:Cognitive Dysfunction / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D003430:Cross-Sectional Studies; D005260:Female; D019788:Fluorodeoxyglucose F18; D005947:Glucose / Q000378:metabolism; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D049268:Positron-Emission Tomography / Q000379:methods; D012372:ROC Curve; D019275:Radiopharmaceuticals; D012039:Regional Blood Flow / Q000502:physiology; D012720:Severity of Illness Index
chemical_list: D016229:Amyloid beta-Peptides; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D005947:Glucose