title: Evidence of subcortical and cortical aging of the acoustic pathway: a diffusion tensor imaging (DTI) study.
abstract: OBJECTIVE
  During aging, there is evidence of microstructural changes in certain cortical and subcortical brain regions. Diffusion tensor imaging (DTI) is used to study age related microstructural changes in the acoustic pathway.
  
  
  METHODS
  Twenty healthy volunteers (mean age 28.5 years) and 15 healthy volunteers (mean age 61.3 years) were examined using a 1.5-T MR system with a high-resolution T1-weighted sequence and an integrated parallel imaging technique DTI Echo-planar-imaging (EPI) sequence. For reliability, 10 subjects underwent a second examination 2 days later. The fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) were measured in six brain regions of the auditory pathway.
  
  
  RESULTS
  We found no left/right asymmetry in the selected brain structures. There were no significant differences (P < .05) in the ADC and FA in the lateral lemniscus and medial geniculate body of young and elderly subjects. However, FA was significantly increased (P < .05) in the inferior colliculus and decreased in the auditory radiation, the superficial temporal gyrus, and the transverse temporal gyrus in the elder subjects than in the younger ones. There were no significant differences in anisotropy in subsequent examinations in the younger individuals.
  
  
  CONCLUSIONS
  These findings suggest evidence of age-related changes in the acoustic pathway. These changes are associated with a decrease in anisotropy mainly in the cortical grey and white matter rather than in the subcortical regions. Our DTI measurements were reproducible.
authors.affiliation: Department of Clinical Radiology, University of Munich, Grosshadern, Marchioninistr. 15, 81377 Munich, Germany. Juergen.Luts@med.uni-muenchen.de
authors.forename: Juergen
authors.initials: J
authors.lastname: Lutz
authors.forename: Felix
authors.initials: F
authors.lastname: Hemminger
authors.forename: Robert
authors.initials: R
authors.lastname: Stahl
authors.forename: Olaf
authors.initials: O
authors.lastname: Dietrich
authors.forename: Martin
authors.initials: M
authors.lastname: Hempel
authors.forename: Maximilian
authors.initials: M
authors.lastname: Reiser
authors.forename: Lorenz
authors.initials: L
authors.lastname: Jäger
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging; D016880:Anisotropy; D001301:Audiometry, Pure-Tone; D001306:Auditory Pathways / Q000033:anatomy & histology*; D001921:Brain / Q000033:anatomy & histology*; D001931:Brain Mapping / Q000379:methods*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results