title: Efficacy of distortion correction on diffusion imaging: comparison of FSL eddy and eddy_correct using 30 and 60 directions diffusion encoding.
abstract: Diffusion imaging is a unique noninvasive tool to detect brain white matter trajectory and integrity in vivo. However, this technique suffers from spatial distortion and signal pileup or dropout originating from local susceptibility gradients and eddy currents. Although there are several methods to mitigate these problems, most techniques can be applicable either to susceptibility or eddy-current induced distortion alone with a few exceptions. The present study compared the correction efficiency of FSL tools, "eddy_correct" and the combination of "eddy" and "topup" in terms of diffusion-derived fractional anisotropy (FA). The brain diffusion images were acquired from 10 healthy subjects using 30 and 60 directions encoding schemes based on the electrostatic repulsive forces. For the 30 directions encoding, 2 sets of diffusion images were acquired with the same parameters, except for the phase-encode blips which had opposing polarities along the anteroposterior direction. For the 60 directions encoding, non-diffusion-weighted and diffusion-weighted images were obtained with forward phase-encoding blips and non-diffusion-weighted images with the same parameter, except for the phase-encode blips, which had opposing polarities. FA images without and with distortion correction were compared in a voxel-wise manner with tract-based spatial statistics. We showed that images corrected with eddy and topup possessed higher FA values than images uncorrected and corrected with eddy_correct with trilinear (FSL default setting) or spline interpolation in most white matter skeletons, using both encoding schemes. Furthermore, the 60 directions encoding scheme was superior as measured by increased FA values to the 30 directions encoding scheme, despite comparable acquisition time. This study supports the combination of eddy and topup as a superior correction tool in diffusion imaging rather than the eddy_correct tool, especially with trilinear interpolation, using 60 directions encoding scheme.
authors.affiliation: Department of Radiology, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Haruyasu
authors.initials: H
authors.lastname: Yamada
authors.affiliation: Department of Radiology, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Abe
authors.affiliation: Department of Radiology, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Shizukuishi
authors.affiliation: Department of Radiology, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Junko
authors.initials: J
authors.lastname: Kikuta
authors.affiliation: Department of Oral Diagnostic Sciences, Nihon University School of Dentistry, Tokyo, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Shinozaki
authors.affiliation: Department of Oral Diagnostic Sciences, Nihon University School of Dentistry, Tokyo, Japan.
authors.forename: Ko
authors.initials: K
authors.lastname: Dezawa
authors.affiliation: Department of Radiological Technology, Nihon University Itabashi Hospital, Tokyo, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Nagano
authors.affiliation: Department of Radiological Technology, Nihon University Itabashi Hospital, Tokyo, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Matsuda
authors.affiliation: Department of Radiology, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Haradome
authors.affiliation: Department of Oral Diagnostic Sciences, Nihon University School of Dentistry, Tokyo, Japan.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Imamura
mesh_terms: D000328:Adult; D000465:Algorithms; D001921:Brain / Q000502:physiology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods* / Q000592:standards; D008297:Male