title: Volume of interest-based fourier transform method for calculation of static magnetic field maps from susceptibility distributions.
abstract: Calculation of static magnetic field (B0 ) inhomogeneity maps of high-resolution susceptibility models by means of convolution with dipole kernels often encounters limitations in computer memory (RAM) for large input data matrices. In many applications, only a small portion of the full volume of the computer model is a volume of interest (VOI) or a susceptibility perturbation source. This work presents a VOI-based method to significantly reduce the computer memory usage for such applications.
  
  
  
  The VOI-based method is presented and compared with the conventional method for calculation of the B0 field in the brain and heart of a human body model in terms of calculation speed, memory requirement, and calculation error relative to the full model results.
  
  
  
  Use of the VOI-based method significantly reduced memory usage in the human body model calculations over the conventional method without loss of accuracy and with comparable calculation speed.
  
  
  
  The proposed method can be valuable for rapid calculation of B0 distributions on standard computer hardware for applications such as subject-specific B0 field calculations derived from anatomic scans. Magn Reson Med 75:2473-2480, 2016. © 2015 Wiley Periodicals, Inc.
authors.affiliation: Center for NMR Research, Department of Radiology, College of Medicine, The Pennsylvania State University, Hershey, Pennsylvania, USA.
authors.forename: Rahul P
authors.initials: RP
authors.lastname: Dewal
authors.affiliation: Center for NMR Research, Department of Radiology, College of Medicine, The Pennsylvania State University, Hershey, Pennsylvania, USA.
authors.forename: Qing X
authors.initials: QX
authors.lastname: Yang
mesh_terms: D000465:Algorithms; D001921:Brain / Q000000981:diagnostic imaging; D005583:Fourier Analysis; D006321:Heart / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008954:Models, Biological; D019047:Phantoms, Imaging
keywords: B0 field maps; magnetic susceptibility; numerical calculations; passive shimming