title: Prospective and retrospective high order eddy current mitigation for diffusion weighted echo planar imaging.
abstract: OBJECTIVE
  The proposed method is aimed at reducing eddy current (EC) induced distortion in diffusion weighted echo planar imaging, without the need to perform further image coregistration between diffusion weighted and T2 images. These ECs typically have significant high order spatial components that cannot be compensated by preemphasis.
  
  
  METHODS
  High order ECs are first calibrated at the system level in a protocol independent fashion. The resulting amplitudes and time constants of high order ECs can then be used to calculate imaging protocol specific corrections. A combined prospective and retrospective approach is proposed to apply correction during data acquisition and image reconstruction.
  
  
  RESULTS
  Various phantom, brain, body, and whole body diffusion weighted images with and without the proposed method are acquired. Significantly reduced image distortion and misregistration are consistently seen in images with the proposed method compared with images without.
  
  
  CONCLUSIONS
  The proposed method is a powerful (e.g., effective at 48 cm field of view and 30 cm slice coverage) and flexible (e.g., compatible with other image enhancements and arbitrary scan plane) technique to correct high order ECs induced distortion and misregistration for various diffusion weighted echo planar imaging applications, without the need for further image post processing, protocol dependent prescan, or sacrifice in signal-to-noise ratio.
authors: Applied Science Laboratory, General Electric Healthcare, Milwaukee, Wisconsin, USA.
authors: Dan
authors: D
authors: Xu
authors: Joseph K
authors: JK
authors: Maier
authors: Kevin F
authors: KF
authors: King
authors: Bruce D
authors: BD
authors: Collick
authors: Gaohong
authors: G
authors: Wu
authors: Robert D
authors: RD
authors: Peters
authors: R Scott
authors: RS
authors: Hinks
mesh_terms: D000465:Algorithms; D016477:Artifacts; D001921:Brain / Q000033:anatomy & histology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D017352:Echo-Planar Imaging / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D060526:Magnetic Fields; D011446:Prospective Studies; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D051598:Whole Body Imaging / Q000379:methods*
keywords: EPI; artifacts; diffusion MRI; distortion; eddy currents