title: Quantitative susceptibility mapping in the abdomen as an imaging biomarker of hepatic iron overload.
abstract: OBJECTIVE
  The purpose of this work was to develop and demonstrate feasibility and initial clinical validation of quantitative susceptibility mapping (QSM) in the abdomen as an imaging biomarker of hepatic iron overload.
  
  
  METHODS
  In general, QSM is faced with the challenges of background field removal and dipole inversion. Respiratory motion, the presence of fat, and severe iron overload further complicate QSM in the abdomen. We propose a technique for QSM in the abdomen that addresses these challenges. Data were acquired from 10 subjects without hepatic iron overload and 33 subjects with known or suspected iron overload. The proposed technique was used to estimate the susceptibility map in the abdomen, from which hepatic iron overload was measured. As a reference, spin-echo data were acquired for R2-based LIC estimation. Liver R2* was measured for correlation with liver susceptibility estimates.
  
  
  RESULTS
  Correlation between susceptibility and R2-based LIC estimation was R(2) = 0.76 at 1.5 Tesla (T) and R(2) = 0.83 at 3T. Furthermore, high correlation between liver susceptibility and liver R2* (R(2) = 0.94 at 1.5T; R(2) = 0.93 at 3T) was observed.
  
  
  CONCLUSIONS
  We have developed and demonstrated initial validation of QSM in the abdomen as an imaging biomarker of hepatic iron overload.
authors.affiliation: Department of Radiology, University of Wisconsin, Madison, Wisconsin, USA.
authors.forename: Samir D
authors.initials: SD
authors.lastname: Sharma
authors.affiliation: Department of Radiology, University of Wisconsin, Madison, Wisconsin, USA.
authors.forename: Diego
authors.initials: D
authors.lastname: Hernando
authors.affiliation: Department of Radiology, University of Wisconsin, Madison, Wisconsin, USA.|Department of Medical Physics, University of Wisconsin, Madison, Wisconsin, USA.
authors.forename: Debra E
authors.initials: DE
authors.lastname: Horng
authors.affiliation: Department of Radiology, University of Wisconsin, Madison, Wisconsin, USA.|Department of Medical Physics, University of Wisconsin, Madison, Wisconsin, USA.|Department of Biomedical Engineering, University of Wisconsin, Madison, Wisconsin, USA.|Department of Medicine, University of Wisconsin, Madison, Wisconsin, USA.
authors.forename: Scott B
authors.initials: SB
authors.lastname: Reeder
mesh_terms: D000005:Abdomen / Q000473:pathology*; D015415:Biomarkers / Q000032:analysis*; D006801:Humans; D007501:Iron / Q000032:analysis; D019190:Iron Overload / Q000175:diagnosis* / Q000473:pathology; D016014:Linear Models; D008099:Liver / Q000737:chemistry* / Q000473:pathology; D008107:Liver Diseases / Q000175:diagnosis* / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*
chemical_list: D015415:Biomarkers; D007501:Iron
keywords: dipole inversion; imaging biomarker; liver iron concentration; magnetic susceptibility; quantitative susceptibility mapping