title: Gender, age-related, and regional differences of the magnetization transfer ratio of the cortical and subcortical brain gray matter.
abstract: OBJECTIVE
  To explore gender, age-related, and regional differences of magnetization transfer ratio (MTR) of brain cortical and subcortical gray matter (GM).
  
  
  METHODS
  In all, 102 healthy subjects (51 women and 51 men; range 25-84 years) were examined with 3-mm thick MT images. We assessed MTR in automatically segmented GM structures including frontal, parietal-insular, temporal, and occipital cortex, caudate, pallidus and putamen, and cerebellar cortex. A general linear model analysis was conducted to ascertain the linear and quadratic relationship among the MTR and gender, age, and anatomical structure.
  
  
  RESULTS
  The effect of gender was borderline (P = 0.07) in all GM structures (with higher MTR values in men), whereas age showed a significant linear as well as quadratic effect in all cortical and subcortical GM structures (P ≤ 0.001). Quadratic age-related decrease in MTR began at about 40 years of age. Mean and standard deviation (SD) of MTR had the following decreasing order: thalamus (58.3 + 0.8), pallidus (56.8 ± 1.3), caudate (55.5 ± 1.6) and putamen (54.6 ± 1.1); temporal (56.8 ± 0.9), parietal-insular (56.8 ± 1.1), frontal (56.5 ± 1.1), occipital (55.4 ± 1.0) and cerebellar (53.2 ± 1.0) cortex. In post-hoc testing, all regional pairwise differences were statistically significant except pallidus vs. temporal or parietal-insular cortex, caudate vs. occipital cortex, frontal vs. parietal-insular or temporal cortex.
  
  
  CONCLUSIONS
  MTR of the cortical and subcortical brain GM structures decreases quadratically after midlife and shows significant regional differences.
authors.affiliation: Quantitative and Functional Neuroradiology Program at Meyer Children's Hospital and Careggi Hospital of Florence, Department of Experimental and Clinical Biomedical Sciences, University of Florence, Florence, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Mascalchi
authors.forename: Nicola
authors.initials: N
authors.lastname: Toschi
authors.forename: Andrea
authors.initials: A
authors.lastname: Ginestroni
authors.forename: Marco
authors.initials: M
authors.lastname: Giannelli
authors.forename: Emanuele
authors.initials: E
authors.lastname: Nicolai
authors.forename: Marco
authors.initials: M
authors.lastname: Aiello
authors.forename: Andrea
authors.initials: A
authors.lastname: Soricelli
authors.forename: Stefano
authors.initials: S
authors.lastname: Diciotti
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000473:pathology* / Q000502:physiology*; D001921:Brain / Q000033:anatomy & histology* / Q000502:physiology*; D005260:Female; D066128:Gray Matter / Q000033:anatomy & histology* / Q000502:physiology*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D060526:Magnetic Fields; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012727:Sex Characteristics
keywords: aging; automatic segmentation; gray matter; magnetization transfer