title: Clinical Correlation of Abnormal Findings on Magnetic Resonance Elastography in Idiopathic Normal Pressure Hydrocephalus.
abstract: BACKGROUND
  Idiopathic normal pressure hydrocephalus (iNPH) is a ventriculomegaly syndrome characterized by dementia, urinary incontinence, and gait disturbance, which is potentially reversible after ventriculoperitoneal shunting (VPS). Magnetic resonance elastography (MRE) is an evolving imaging technology that noninvasively measures tissue viscoelasticity. We studied iNPH patients using MRE prior to shunting, compared them with normal controls, and analyzed associations between MRE findings and clinical features, as a pilot assessment of MRE in iNPH.
  
  
  METHODS
  Stiffness values were measured on preoperative MRE in 10 iNPH patients scheduled for VPS and compared with those in 20 age- and sex-matched controls. Stiffness results were correlated with clinical iNPH symptoms.
  
  
  RESULTS
  MRE demonstrated significantly increased stiffness in iNPH in cerebrum (P = 0.04), occipital (P = 0.002), and parietal (P = 0.01) regions of interest (ROIs) and significantly decreased stiffness in periventricular ROIs (P < 0.0001). Stiffness was not significantly different in frontal (P = 0.1) and deep gray ROIs (P = 0.4). Univariate analysis showed associations between preoperative iNPH symptoms and abnormally increased stiffness, including urinary incontinence with cerebrum (P = 0.005), frontal (P = 0.04), and cerebellum (P = 0.03) ROIs, and Parkinsonism with occipital ROI (P = 0.04). Postoperative improvement was associated with increased deep gray stiffness (P = 0.01); failure was associated with increased temporal (P = 0.0002) stiffness.
  
  
  CONCLUSIONS
  Based on the preliminary results of this small, limited analysis, brain stiffness may be altered in iNPH, and these alterations in parenchymal viscoelastic properties may be correlated with clinical symptoms. Increased temporal stiffness may predict surgical failure and potentially suggest an alternative dementing pathology underlying the iNPH-like symptoms. These findings highlight the potential future utility of MRE in iNPH management.
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Avital
authors.initials: A
authors.lastname: Perry
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Graffeo
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Nikoo
authors.initials: N
authors.lastname: Fattahi
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Mona M
authors.initials: MM
authors.lastname: ElSheikh
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Nealey
authors.initials: N
authors.lastname: Cray
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Arvin
authors.initials: A
authors.lastname: Arani
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Ehman
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Glaser
authors.affiliation: Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Armando
authors.initials: A
authors.lastname: Manduca
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota, USA.
authors.forename: Fredric B
authors.initials: FB
authors.lastname: Meyer
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, Minnesota, USA. Electronic address: Huston.John@mayo.edu.
authors.forename: John
authors.initials: J
authors.lastname: Huston
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000000981:diagnostic imaging*; D002552:Cerebral Ventricles / Q000000981:diagnostic imaging; D054022:Cerebrum / Q000000981:diagnostic imaging; D054459:Elasticity Imaging Techniques; D005260:Female; D005625:Frontal Lobe / Q000000981:diagnostic imaging; D020233:Gait Disorders, Neurologic / Q000209:etiology; D066128:Gray Matter / Q000000981:diagnostic imaging; D006801:Humans; D006849:Hydrocephalus / Q000000981:diagnostic imaging* / Q000209:etiology; D006850:Hydrocephalus, Normal Pressure / Q000150:complications / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging; D008297:Male; D009778:Occipital Lobe / Q000000981:diagnostic imaging; D010296:Parietal Lobe / Q000000981:diagnostic imaging; D014549:Urinary Incontinence / Q000209:etiology
keywords: Idiopathic normal pressure hydrocephalus; Magnetic resonance elastography; Periventricular white matter