RT Journal Article SR Electronic T1 Differential Diagnosis of Normal Pressure Hydrocephalus by MRI Mean Diffusivity Histogram Analysis JF American Journal of Neuroradiology JO Am. J. Neuroradiol. FD American Society of Neuroradiology DO 10.3174/ajnr.A3368 A1 M. Ivkovic A1 B. Liu A1 F. Ahmed A1 D. Moore A1 C. Huang A1 A. Raj A1 I. Kovanlikaya A1 L. Heier A1 N. Relkin YR 2012 UL http://www.ajnr.org/content/early/2012/12/20/ajnr.A3368.abstract AB BACKGROUND AND PURPOSE: 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.Wehypothesized that radiologic differences between NPH and AD/PD can be characterized by a robust and objectiveMRimaging DTI technique that does not require intersubject image registration or operator-defined regions of interest, thus avoiding many pitfalls common in DTI methods. MATERIALS AND 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. Abbreviations ADAlzheimer diseaseDb dementia with Lewy bodiesNPHnormal pressure hydrocephalusMDmean diffusivityPDParkinson disease