title: Correction of eddy-current distortions in diffusion tensor images using the known directions and strengths of diffusion gradients.
abstract: OBJECTIVE
  To correct eddy-current artifacts in diffusion tensor (DT) images without the need to obtain auxiliary scans for the sole purpose of correction.
  
  
  METHODS
  DT images are susceptible to distortions caused by eddy currents induced by large diffusion gradients. We propose a new postacquisition correction algorithm that does not require any auxiliary reference scans. It also avoids the problematic procedure of cross-correlating images with significantly different contrasts. A linear model is used to describe the dependence of distortion parameters (translation, scaling, and shear) on the diffusion gradients. The model is solved numerically to provide an individual correction for every diffusion-weighted (DW) image.
  
  
  RESULTS
  The assumptions of the linear model were successfully verified in a series of experiments on a silicon oil phantom. The correction obtained for this phantom was compared with correction obtained by a previously published method. The algorithm was then shown to markedly reduce eddy-current distortions in DT images from human subjects.
  
  
  CONCLUSIONS
  The proposed algorithm can accurately correct eddy-current artifacts in DT images. Its principal advantages are that only images with comparable signals and contrasts are cross-correlated, and no additional scans are required.
authors.affiliation: Magnetic Resonance Imaging Unit, Department of Psychiatry, Columbia College of Physicians and Surgeons, New York, New York, USA. jc.zhuang@gmail.com
authors.forename: Jiancheng
authors.initials: J
authors.lastname: Zhuang
authors.forename: Jan
authors.initials: J
authors.lastname: Hrabe
authors.forename: Alayar
authors.initials: A
authors.lastname: Kangarlu
authors.forename: Dongrong
authors.initials: D
authors.lastname: Xu
authors.forename: Ravi
authors.initials: R
authors.lastname: Bansal
authors.forename: Craig A
authors.initials: CA
authors.lastname: Branch
authors.forename: Bradley S
authors.initials: BS
authors.lastname: Peterson
mesh_terms: D000465:Algorithms; D001921:Brain / Q000033:anatomy & histology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D017352:Echo-Planar Imaging / Q000295:instrumentation / Q000379:methods*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity