title: Effect of age on MRI phase behavior in the subcortical deep gray matter of healthy individuals.
abstract: OBJECTIVE
  It has been demonstrated that increased levels of iron in the brain occur with aging. In this study we investigated the nature of the association between age and SWI-filtered phase values, indicative of iron content, in the subcortical deep gray matter of healthy individuals.
  
  
  METHODS
  A total of 210 healthy individuals (men: n = 89, women: n = 121), mean age, 39.8 years (standard deviation = 15.5; range = 6-76 years), were imaged on a 3T scanner. Mean MRI phase, mean phase of low-phase voxels, and normalized volumes were determined for total subcortical deep gray matter, caudate, putamen, globus pallidus, thalamus, pulvinar nucleus, hippocampus, amygdala, nucleus accumbens, red nucleus, and substantia nigra. Linear and nonlinear regression models were used to explore the relationship between phase and volume measures, and aging.
  
  
  RESULTS
  Mean phase values of subcortical deep gray matter structures showed a quadratic relationship, with individuals in late middle age (40-59 years) having the lowest mean phase values, followed by a reversal of this trend in the elderly. In contrast, mean phase of low-phase voxel measurements showed strong negative linear relationships with aging. Significantly lower phase values were detected in women compared with men (P < .001), whereas no sex differences were observed for mean phase of low-phase voxels. Normalized volume measurements were also linearly related to aging, and women showed smaller normalized volumes of subcortical deep gray matter structures than men (P < .001). Lower mean phase of low-phase voxels was related to decreased volume measures.
  
  
  CONCLUSIONS
  A strong association between phase (quadratic effect; phase decreases are followed by increases), mean phase of low-phase voxels (linear effect), volume (linear effect), and age was observed. Low phase was related to brain atrophy.
authors.affiliation: Buffalo Neuroimaging Analysis Center, Department of Neurology, University at Buffalo, Buffalo, New York.
authors.forename: J
authors.initials: J
authors.lastname: Hagemeier
authors.forename: M G
authors.initials: MG
authors.lastname: Dwyer
authors.forename: N
authors.initials: N
authors.lastname: Bergsland
authors.forename: F
authors.initials: F
authors.lastname: Schweser
authors.forename: C R
authors.initials: CR
authors.lastname: Magnano
authors.forename: M
authors.initials: M
authors.lastname: Heininen-Brown
authors.forename: D P
authors.initials: DP
authors.lastname: Ramasamy
authors.forename: E
authors.initials: E
authors.lastname: Carl
authors.forename: C
authors.initials: C
authors.lastname: Kennedy
authors.forename: R
authors.initials: R
authors.lastname: Melia
authors.forename: P
authors.initials: P
authors.lastname: Polak
authors.forename: A
authors.initials: A
authors.lastname: Deistung
authors.forename: J J G
authors.initials: JJ
authors.lastname: Geurts
authors.forename: J R
authors.initials: JR
authors.lastname: Reichenbach
authors.forename: R
authors.initials: R
authors.lastname: Zivadinov
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000473:pathology*; D000465:Algorithms; D001284:Atrophy / Q000473:pathology; D001921:Brain / Q000473:pathology*; D002648:Child; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009474:Neurons / Q000473:pathology*; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult