title: 18F-FDG PET Improves Diagnosis in Patients with Focal-Onset Dementias.
abstract: Alzheimer disease is the cause of up to one-third of cases of primary progressive aphasia or corticobasal syndrome. The primary objective of this study was to determine the accuracy of 18F-FDG PET metabolic imaging for the detection of Alzheimer disease in patients with primary progressive aphasia or corticobasal syndrome.
  
  
  METHODS
  A cohort of patients (n=94), including those with an expert clinical diagnosis of logopenic (n=19), nonfluent (n=16), or semantic (n=13) variants of primary progressive aphasia, corticobasal syndrome (n=14), or Alzheimer disease (n=24), underwent 18F-FDG metabolic and 11C-labeled Pittsburgh compound B (11C-PiB) amyloid PET brain imaging. 18F-FDG PET scans interpreted with Neurostat and 3D-SSP displays were classified as revealing Alzheimer disease or "other" by interpreters who were unaware of the clinical assessments and 11C-PiB PET results. 11C-PiB PET imaging was considered to be the diagnostic reference standard, with a threshold standardized uptake value ratio of 1.5 being indicative of Alzheimer disease pathology. To address possible bias from subgroup selection for the Alzheimer disease binary classifier, we calculated both conventional and balanced accuracies.
  
  
  RESULTS
  Diagnoses of Alzheimer disease based on 18F-FDG PET resulted in 84% accuracy (both conventional and balanced). In comparison, diagnoses based on clinical assessments resulted in 65% conventional accuracy and 67% balanced accuracy.
  
  
  CONCLUSIONS
  Brain 18F-FDG PET scans interpreted with Neurostat and 3D-SSP displays accurately detected Alzheimer disease in patients with primary progressive aphasia or corticobasal syndrome as focal-onset dementias. In such diagnostically challenging cohorts, (18)F-FDG PET imaging can provide more accurate diagnoses, enabling more appropriate therapy.
authors.affiliation: Department of Psychiatry, University of California San Diego, San Diego, California ctaswell@ucsd.edu.
authors.forename: Carl
authors.initials: C
authors.lastname: Taswell
authors.affiliation: Austin Health Department Molecular Imaging, Melbourne, Victoria, Australia.
authors.forename: Victor L
authors.initials: VL
authors.lastname: Villemagne
authors.affiliation: Austin Health Department Molecular Imaging, Melbourne, Victoria, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Yates
authors.affiliation: NIRS Molecular Imaging Center, Chiba, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Shimada
authors.affiliation: University of Sydney Health Sciences, Sydney, New South Wales, Australia.
authors.forename: Cristian E
authors.initials: CE
authors.lastname: Leyton
authors.affiliation: University of Sydney Health Sciences, Sydney, New South Wales, Australia.
authors.forename: Kirrie J
authors.initials: KJ
authors.lastname: Ballard
authors.affiliation: ARC Centre of Excellence in Cognition and Its Disorders, Neuroscience Research Australia, Sydney, New South Wales, Australia; and University of New South Wales Medical Sciences, Sydney, New South Wales, Australia.
authors.forename: Olivier
authors.initials: O
authors.lastname: Piguet
authors.affiliation: ARC Centre of Excellence in Cognition and Its Disorders, Neuroscience Research Australia, Sydney, New South Wales, Australia; and University of New South Wales Medical Sciences, Sydney, New South Wales, Australia.
authors.forename: James R
authors.initials: JR
authors.lastname: Burrell
authors.affiliation: ARC Centre of Excellence in Cognition and Its Disorders, Neuroscience Research Australia, Sydney, New South Wales, Australia; and University of New South Wales Medical Sciences, Sydney, New South Wales, Australia.
authors.forename: John R
authors.initials: JR
authors.lastname: Hodges
authors.affiliation: Austin Health Department Molecular Imaging, Melbourne, Victoria, Australia.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Rowe
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis / Q000000981:diagnostic imaging; D018888:Aphasia, Primary Progressive / Q000175:diagnosis / Q000000981:diagnostic imaging; D001921:Brain / Q000000981:diagnostic imaging; D003704:Dementia / Q000175:diagnosis* / Q000000981:diagnostic imaging*; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008297:Male; D008875:Middle Aged; D049268:Positron-Emission Tomography / Q000379:methods*; D011237:Predictive Value of Tests; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
keywords: 11C-PiB; 18F-FDG; Alzheimer disease; PET brain imaging; focal-onset dementias