title: Accelerated 4D quantitative single point EPR imaging using model-based reconstruction.
abstract: OBJECTIVE
  Electron paramagnetic resonance imaging has surfaced as a promising noninvasive imaging modality that is capable of imaging tissue oxygenation. Due to extremely short spin-spin relaxation times, electron paramagnetic resonance imaging benefits from single-point imaging and inherently suffers from limited spatial and temporal resolution, preventing localization of small hypoxic tissues and differentiation of hypoxia dynamics, making accelerated imaging a crucial issue.
  
  
  METHODS
  In this study, methods for accelerated single-point imaging were developed by combining a bilateral k-space extrapolation technique with model-based reconstruction that benefits from dense sampling in the parameter domain (measurement of the T2 (*) decay of a free induction delay). In bilateral kspace extrapolation, more k-space samples are obtained in a sparsely sampled region by bilaterally extrapolating data from temporally neighboring k-spaces. To improve the accuracy of T2 (*) estimation, a principal component analysis-based method was implemented.
  
  
  RESULTS
  In a computer simulation and a phantom experiment, the proposed methods showed its capability for reliable T2 (*) estimation with high acceleration (8-fold, 15-fold, and 30-fold accelerations for 61×61×61, 95×95×95, and 127×127×127 matrix, respectively).
  
  
  CONCLUSIONS
  By applying bilateral k-space extrapolation and model-based reconstruction, improved scan times with higher spatial resolution can be achieved in the current single-point electron paramagnetic resonance imaging modality.
authors.affiliation: Department of Radiology, Wisconsin Institute for Medical Research, University of Wisconsin, Madison, Wisconsin, USA.
authors.forename: Hyungseok
authors.initials: H
authors.lastname: Jang
authors.forename: Shingo
authors.initials: S
authors.lastname: Matsumoto
authors.forename: Nallathamby
authors.initials: N
authors.lastname: Devasahayam
authors.forename: Sankaran
authors.initials: S
authors.lastname: Subramanian
authors.forename: Jiachen
authors.initials: J
authors.lastname: Zhuo
authors.forename: Murali C
authors.initials: MC
authors.lastname: Krishna
authors.forename: Alan B
authors.initials: AB
authors.lastname: McMillan
mesh_terms: D000465:Algorithms; D003198:Computer Simulation; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008954:Models, Biological; D057054:Molecular Imaging / Q000379:methods*; D010092:Oximetry / Q000379:methods*; D010100:Oxygen / Q000032:analysis*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D010100:Oxygen
keywords: Electron paramagnetic resonance imaging; k-space extrapolation; model-based reconstruction; quantitative imaging; single-point imaging