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... with subject motion. We account for subject motion by registering each fMRI time point volume to the first time point using a rigid body transformation computed using a normalized correlation metric =-=[7]-=-. We then use these transformations to remap the estimated deformation field to the space of each time point and apply the distortion correction in the native space of each image. We then apply the in...

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... in the phase-encode direction than in the frequency-encode direction). Therefore the first step of the algorithm is to use the multi-resolution, mutual information method described in Thevenaz et al =-=[8]-=- to compute a rigid transformation that maps the T1 image data to the space of the first time point volume in the fMRI time series. We then use this transform to resample the T1 image to the fMRI spac...

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...ain magnetic field can cause large geometric distortions along the phase-encode direction of echo planar images (EPI) [1]. In fMRI, these distortions in the EPI data can lead to local shifts of 6-9mm =-=[5]-=- in inferior slices and signal pile-up [6]. Approaches to correcting distortions caused by field inhomogeneities include field mapping [5, 3] and non-linear registration with an undistorted reference ...

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...ic distortions along the phase-encode direction of echo planar images (EPI) [1]. In fMRI, these distortions in the EPI data can lead to local shifts of 6-9mm [5] in inferior slices and signal pile-up =-=[6]-=-. Approaches to correcting distortions caused by field inhomogeneities include field mapping [5, 3] and non-linear registration with an undistorted reference image (usually a T1- or T2- weighted) [4, ...

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... [6]. Approaches to correcting distortions caused by field inhomogeneities include field mapping [5, 3] and non-linear registration with an undistorted reference image (usually a T1- or T2- weighted) =-=[4, 1]-=-. We previously developed a method for correcting distortion in the EPI images used in diffusion weighted imaging (DWI) [1]. In that work, we estimated a correction field by non-rigidly registering th...

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...distortions in the EPI data can lead to local shifts of 6-9mm [5] in inferior slices and signal pile-up [6]. Approaches to correcting distortions caused by field inhomogeneities include field mapping =-=[5, 3]-=- and non-linear registration with an undistorted reference image (usually a T1- or T2- weighted) [4, 1]. We previously developed a method for correcting distortion in the EPI images used in diffusion ...

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...les, United States Introduction: It is well known that spatial variations of the main magnetic field can cause large geometric distortions along the phase-encode direction of echo planar images (EPI) =-=[1]-=-. In fMRI, these distortions in the EPI data can lead to local shifts of 6-9mm [5] in inferior slices and signal pile-up [6]. Approaches to correcting distortions caused by field inhomogeneities inclu...