title: Susceptibility underestimation in a high-susceptibility phantom: Dependence on imaging resolution, magnitude contrast, and other parameters.
abstract: We assessed the accuracy of quantitative susceptibility mapping in a gadolinium balloon phantom with a large range of susceptibility values and imaging resolutions at 1.5 and 3 Tesla (T).
  
  
  
  The phantom contained sources with susceptibility values of 0.4, 0.8, 1.6, and 3.2 ppm and was imaged at isotropic resolutions of 0.7, 0.8, 1.2, and 1.8 mm. Numerical simulations were performed to match the experimental findings. Voxel sensitivity effects were used to explain the susceptibility underestimations.
  
  
  
  Both phantom data and simulation demonstrated that systematic underestimation of the susceptibility values increased with voxel size, field strength, and object susceptibility.
  
  
  
  The underestimation originates from the signal formation in a voxel, which can be described by the voxel sensitivity function. The amount of underestimation is thus affected by imaging resolution, magnitude contrast, image filtering, and details of the susceptibility inclusions such as the susceptibility value and geometry. High-resolution imaging is therefore needed for accurate reconstruction of QSM values, especially at higher susceptibilities. Magn Reson Med 78:1080-1086, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
authors.affiliation: Department of Radiology, Weill Cornell Medical College, New York, New York, USA.
authors.forename: Dong
authors.initials: D
authors.lastname: Zhou
authors.affiliation: Department of Biomedical Engineering, Cornell University, Ithaca, New York, USA.
authors.forename: Junghun
authors.initials: J
authors.lastname: Cho
authors.affiliation: Department of Biomedical Engineering, Cornell University, Ithaca, New York, USA.
authors.forename: Jingwei
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Radiology, Weill Cornell Medical College, New York, New York, USA.
authors.forename: Pascal
authors.initials: P
authors.lastname: Spincemaille
authors.affiliation: Department of Radiology, Weill Cornell Medical College, New York, New York, USA.|Department of Biomedical Engineering, Cornell University, Ithaca, New York, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D019047:Phantoms, Imaging
keywords: imaging resolution; k-space filter; magnetic susceptibility; sample orientation; underestimation; voxel sensitivity function