title: Enhanced detection of diffusion reductions in Creutzfeldt-Jakob disease at a higher B factor.
abstract: OBJECTIVE
  Diffusion-weighted imaging (DWI) is sensitive to the cerebral manifestations of human prion diseases. The magnitude of diffusion weighting, termed "b factor," has only been evaluated at the standard b = 1000 s/mm(2). This is the first rigorous evaluation of b = 2000 s/mm(2) in Creutzfeldt-Jakob Disease (CJD).
  
  
  METHODS
  We compared DWI characteristics of 13 patients with CJD and 15 healthy controls at b = 1000 s/mm(2) and b = 2000 s/mm(2). Apparent diffusion coefficients (ADC) were computed and analyzed for the whole brain by voxel-wise analysis (by SPM5) as well as in anatomically defined volumes of interest (by FSL FIRST).
  
  
  RESULTS
  Measured ADC was significantly lower (by approximately 5%-15%) at b = 2000 s/mm(2) than at b = 1000 s/mm(2) and significantly lower in patients than in controls. The differences between patients and controls were greater and more extensive at b = 2000 s/mm(2) than at b = 1000 s/mm(2) in the expected regions (thalamus, putamen, and caudate nucleus).
  
  
  CONCLUSIONS
  Because higher b factors change the absolute value of observed ADC, as well as lesion detection, care should be taken when combining studies using different b factors. While the clinical application of high b factors is currently limited by a low signal intensity-to-noise ratio, it may offer more information in questionable cases, and our results confirm and extend the central role of diffusion imaging in human prion diseases.
authors.affiliation: Department of Psychiatry, Mount Sinai School of Medicine, One Gustave Levy Pl, New York, NY 10029, USA.
authors.forename: H
authors.initials: H
authors.lastname: Lee
authors.forename: C
authors.initials: C
authors.lastname: Hoffman
authors.forename: P B
authors.initials: PB
authors.lastname: Kingsley
authors.forename: A
authors.initials: A
authors.lastname: Degnan
authors.forename: O
authors.initials: O
authors.lastname: Cohen
authors.forename: I
authors.initials: I
authors.lastname: Prohovnik
mesh_terms: D007562:Creutzfeldt-Jakob Syndrome / Q000175:diagnosis*; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies