title: Diffusion-weighted MR imaging in normal human brains in various age groups.
abstract: OBJECTIVE
  Few studies have concerned the absolute apparent diffusion coefficient (ADC) values in the normal human brain and the effect of aging on diffusion. Therefore, our purpose was to determine whether the average ADC (ADC(av)) values in the various regions of the brain differ with age, sex, or hemisphere and to establish reference values of the absolute ADC(av) for further studies.
  
  
  METHODS
  Subjects (40 men and 40 women) were chosen from a healthy population; age groups were 20-34, 35-49, and 50-64 years and 65 years or older (n = 20 each). All subjects were examined with MR imaging, including conventional and diffusion-weighted imaging in three orthogonal directions with two b values (0 and 1000 s/mm(2)) at 1.5 T. Bilateral ADC(av) values were determined in 36 regions of interest encompassing the entire brain.
  
  
  RESULTS
  ADC(av) values were highest in the cortical gray matter ([0.89 +/- 0.04] x 10(-3) mm(2)/s; range, 0.78-1.09 x 10(-3)), lower in the deep gray matter ([0.75 +/- 0.03] x 10(-3) mm(2)/s; range, 0.64-0.83 x 10(-3)), and lowest in the white matter ([0.70 +/- 0.03] x 10(-3) mm(2)/s; range, 0.62-0.79 x 10(-3)). The ADC(av) values did not significantly change with aging, except for an increase in the lateral ventricles. No difference was observed between women and men or between the hemispheres.
  
  
  CONCLUSIONS
  The data reported herein are representative, and the ADC(av) values can be used for reference in future studies and in clinical settings.
authors.affiliation: Department of Neurology, Helsinki University Central Hospital, Haartmaninkatu 4, 00290 Helsinki, Finland.
authors.forename: Johanna
authors.initials: J
authors.lastname: Helenius
authors.forename: Lauri
authors.initials: L
authors.lastname: Soinne
authors.forename: Jussi
authors.initials: J
authors.lastname: Perkiö
authors.forename: Oili
authors.initials: O
authors.lastname: Salonen
authors.forename: Aki
authors.initials: A
authors.lastname: Kangasmäki
authors.forename: Markku
authors.initials: M
authors.lastname: Kaste
authors.forename: Richard A D
authors.initials: RA
authors.lastname: Carano
authors.forename: Hannu J
authors.initials: HJ
authors.lastname: Aronen
authors.forename: Turgut
authors.initials: T
authors.lastname: Tatlisumak
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001921:Brain / Q000033:anatomy & histology*; D004058:Diffusion; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012016:Reference Values