title: Assessing global and regional iron content in deep gray matter as a function of age using susceptibility mapping.
abstract: To investigate the correlation of non-heme iron content in deep gray matter nuclei as a function of age using quantitative susceptibility mapping (QSM) from both whole-structural and regional perspectives.
  
  
  
  We studied a group of 174 normal subjects ranging from 20 to 69 years old and measured the magnetic susceptibility of seven subcortical gray matter nuclei. SWI (susceptibility-weighted imaging) phase images were used to generate the susceptibility maps, which were acquired on a 1.5T scanner. The 3D whole-structural measurements were used to determine age-related thresholds, which were applied to calculate the local iron deposition (RII: portion of the structure that contains iron concentration larger than the structure threshold). Age-susceptibility correlation was reported for each measured structure for both the whole-region and two-region (low iron and high iron content regions) analysis.
  
  
  
  For the local high iron content region, a strong age-susceptibility correlation was found in the caudate nucleus (CN,R = 0.9), putamen (PUT,R = 0.9), red nucleus (RN,R = 0.8), globus pallidus (GP,R = 0.7), substantia nigra (SN,R = 0.5), and pulvinar thalamus (PT,R = 0.5); for the global iron content, a strong age-susceptibility correlation was found in CN(R = 0.6), PUT(R = 0.7), and RN(R = 0.6). Overall, for each structure analyzed in this study, regional analysis showed higher correlation coefficient and higher slope comparing to the whole-region analysis. Further, we found the quantitative conversion factor between magnetic susceptibility and iron concentration to be 1.03 ± 0.03 ppb per μg iron/g wet tissue.
  
  
  
  We conclude that the age-susceptibility correlation can serve as a quantitative magnetic susceptibility baseline as a function of age for monitoring abnormal global and regional iron deposition. A regional analysis has shown a tighter age related behavior, providing a reliable and sensitive reference for what can be considered normal iron content for studies of neurodegenerative diseases. J. Magn. Reson. Imaging 2016;44:59-71.
authors.affiliation: Wayne State University, Department of Biomedical Engineering, Detroit, Michigan, USA.
authors.forename: Manju
authors.initials: M
authors.lastname: Liu
authors.affiliation: MRI Institute for Biomedical Research, Waterloo, Ontario, Canada.
authors.forename: Saifeng
authors.initials: S
authors.lastname: Liu
authors.affiliation: Wayne State University, Department of Biomedical Engineering, Detroit, Michigan, USA.
authors.forename: Kiarash
authors.initials: K
authors.lastname: Ghassaban
authors.affiliation: HUH-MR Research/Radiology, Wayne State University, Detroit, Michigan, USA.
authors.forename: Weili
authors.initials: W
authors.lastname: Zheng
authors.affiliation: MRI Institute for Biomedical Research, Detroit, Michigan, USA.
authors.forename: Dane
authors.initials: D
authors.lastname: Dicicco
authors.affiliation: Department of Radiology, First Affiliated Hospital, Dalian, Liaoning, China.
authors.forename: Yanwei
authors.initials: Y
authors.lastname: Miao
authors.affiliation: HUH-MR Research/Radiology, Wayne State University, Detroit, Michigan, USA.
authors.forename: Charbel
authors.initials: C
authors.lastname: Habib
authors.affiliation: MRI Institute for Biomedical Research, Detroit, Michigan, USA.
authors.forename: Tarek
authors.initials: T
authors.lastname: Jazmati
authors.affiliation: Wayne State University, Department of Biomedical Engineering, Detroit, Michigan, USA.|MRI Institute for Biomedical Research, Waterloo, Ontario, Canada.|HUH-MR Research/Radiology, Wayne State University, Detroit, Michigan, USA.|MRI Institute for Biomedical Research, Detroit, Michigan, USA.
authors.forename: E Mark
authors.initials: EM
authors.lastname: Haacke
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D005260:Female; D066128:Gray Matter / Q000378:metabolism*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D007501:Iron / Q000378:metabolism*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D057054:Molecular Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014018:Tissue Distribution
chemical_list: D007501:Iron
keywords: brain iron; ferritin; quantitative susceptibility mapping (QSM); two-region analysis (RII)