title: Voxel-based diffusion tensor magnetic resonance imaging evaluation of low-grade hepatic encephalopathy.
abstract: OBJECTIVE
  To quantify the changes in brain water diffusivity in hepatic encephalopathy (HE) associated with cirrhosis using diffusion tensor imaging (DTI) and to correlate with neuropsychological (NP) scores.
  
  
  METHODS
  DTI was performed in 14 patients with low-grade HE and age/gender-comparable 16 healthy controls. Whole brain mean diffusivity (MD) and fractional anisotropy (FA) maps were calculated, normalized to common space, smoothed, and compared voxel-by-voxel between groups using analysis of covariance with age included as a covariate. The average MD and FA values were also calculated from individual subjects for selected brain regions and correlated with the neuropsychological scores.
  
  
  RESULTS
  Patients with HE showed increased MD in the cortical gray and white matter and the internal capsule. Less extensive brain regions with decreased FA were observed in the bilateral frontal and occipital white matter. MD values from the corpus callosum correlated inversely with several NP scores among HE patients and controls. Positive correlations were observed with FA values and cognitive scores.
  
  
  CONCLUSIONS
  Voxel-based DTI analysis showed widespread brain regions with increased MD values, indicating enhanced water content and decreased FA in cirrhotic patients with HE. The MD and FA values from selected regions correlated with the NP scores.
authors.affiliation: Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, California 90095-1721, USA.
authors.forename: Rajesh
authors.initials: R
authors.lastname: Kumar
authors.forename: Rakesh K
authors.initials: RK
authors.lastname: Gupta
authors.forename: Virginia
authors.initials: V
authors.lastname: Elderkin-Thompson
authors.forename: Amir
authors.initials: A
authors.lastname: Huda
authors.forename: James
authors.initials: J
authors.lastname: Sayre
authors.forename: Claudia
authors.initials: C
authors.lastname: Kirsch
authors.forename: Barry
authors.initials: B
authors.lastname: Guze
authors.forename: Steve
authors.initials: S
authors.lastname: Han
authors.forename: M Albert
authors.initials: MA
authors.lastname: Thomas
mesh_terms: D000328:Adult; D000368:Aged; D001929:Brain Edema / Q000175:diagnosis* / Q000209:etiology* / Q000503:physiopathology; D016022:Case-Control Studies; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006501:Hepatic Encephalopathy / Q000150:complications* / Q000523:psychology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011594:Psychometrics