title: Differential diagnosis of normal pressure hydrocephalus by MRI mean diffusivity histogram analysis.
abstract: OBJECTIVE
  Accurate diagnosis of normal pressure hydrocephalus is challenging because the clinical symptoms and radiographic appearance of NPH often overlap those of other conditions, including age-related neurodegenerative disorders such as Alzheimer and Parkinson diseases. We hypothesized that radiologic differences between NPH and AD/PD can be characterized by a robust and objective MR imaging DTI technique that does not require intersubject image registration or operator-defined regions of interest, thus avoiding many pitfalls common in DTI methods.
  
  
  METHODS
  We collected 3T DTI data from 15 patients with probable NPH and 25 controls with AD, PD, or dementia with Lewy bodies. We developed a parametric model for the shape of intracranial mean diffusivity histograms that separates brain and ventricular components from a third component composed mostly of partial volume voxels. To accurately fit the shape of the third component, we constructed a parametric function named the generalized Voss-Dyke function. We then examined the use of the fitting parameters for the differential diagnosis of NPH from AD, PD, and DLB.
  
  
  RESULTS
  Using parameters for the MD histogram shape, we distinguished clinically probable NPH from the 3 other disorders with 86% sensitivity and 96% specificity. The technique yielded 86% sensitivity and 88% specificity when differentiating NPH from AD only.
  
  
  CONCLUSIONS
  An adequate parametric model for the shape of intracranial MD histograms can distinguish NPH from AD, PD, or DLB with high sensitivity and specificity.
authors.affiliation: Weill Cornell Medical College, New York, NY 10021, USA.
authors.forename: M
authors.initials: M
authors.lastname: Ivkovic
authors.forename: B
authors.initials: B
authors.lastname: Liu
authors.forename: F
authors.initials: F
authors.lastname: Ahmed
authors.forename: D
authors.initials: D
authors.lastname: Moore
authors.forename: C
authors.initials: C
authors.lastname: Huang
authors.forename: A
authors.initials: A
authors.lastname: Raj
authors.forename: I
authors.initials: I
authors.lastname: Kovanlikaya
authors.forename: L
authors.initials: L
authors.lastname: Heier
authors.forename: N
authors.initials: N
authors.lastname: Relkin
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis / Q000473:pathology / Q000503:physiopathology; D001921:Brain / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D007091:Image Processing, Computer-Assisted / Q000379:methods / Q000592:standards; D020961:Lewy Body Disease / Q000175:diagnosis / Q000473:pathology / Q000503:physiopathology; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D019636:Neurodegenerative Diseases / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D010300:Parkinson Disease / Q000175:diagnosis / Q000473:pathology / Q000503:physiopathology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity