title: Accelerating EPI distortion correction by utilizing a modern GPU-based parallel computation.
abstract: OBJECTIVE
  The combination of phase demodulation and field mapping is a practical method to correct echo planar imaging (EPI) geometric distortion. However, since phase dispersion accumulates in each phase-encoding step, the calculation complexity of phase modulation is Ny-fold higher than conventional image reconstructions. Thus, correcting EPI images via phase demodulation is generally a time-consuming task.
  
  
  METHODS
  Parallel computing by employing general-purpose calculations on graphics processing units (GPU) can accelerate scientific computing if the algorithm is parallelized. This study proposes a method that incorporates the GPU-based technique into phase demodulation calculations to reduce computation time. The proposed parallel algorithm was applied to a PROPELLER-EPI diffusion tensor data set.
  
  
  RESULTS
  The GPU-based phase demodulation method reduced the EPI distortion correctly, and accelerated the computation. The total reconstruction time of the 16-slice PROPELLER-EPI diffusion tensor images with matrix size of 128 × 128 was reduced from 1,754 seconds to 101 seconds by utilizing the parallelized 4-GPU program.
  
  
  CONCLUSIONS
  GPU computing is a promising method to accelerate EPI geometric correction. The resulting reduction in computation time of phase demodulation should accelerate postprocessing for studies performed with EPI, and should effectuate the PROPELLER-EPI technique for clinical practice.
authors.affiliation: Department of Electrical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan, ROC.
authors.forename: Yao-Hao
authors.initials: YH
authors.lastname: Yang
authors.forename: Teng-Yi
authors.initials: TY
authors.lastname: Huang
authors.forename: Fu-Nien
authors.initials: FN
authors.lastname: Wang
authors.forename: Tzu-Chao
authors.initials: TC
authors.lastname: Chuang
authors.forename: Nan-Kuei
authors.initials: NK
authors.lastname: Chen
mesh_terms: D000465:Algorithms; D016477:Artifacts; D001921:Brain / Q000033:anatomy & histology*; D003196:Computer Graphics / Q000295:instrumentation*; D017352:Echo-Planar Imaging / Q000295:instrumentation* / Q000379:methods*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation* / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity