2012
DOI: 10.1002/mrm.24285
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Combined prospective and retrospective correction to reduce motion‐induced image misalignment and geometric distortions in EPI

Abstract: Despite rigid-body realignment to compensate for head motion during an echo-planar imaging (EPI) time-series scan, non-rigid image deformations remain due to changes in the effective shim within the brain as the head moves through the B0 field. The current work presents a combined prospective/retrospective solution to reduce both rigid and non-rigid components of this motion-related image misalignment. Prospective rigid-body correction, where the scan-plane orientation is dynamically updated to track with the … Show more

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Cited by 36 publications
(42 citation statements)
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“…Our previous study analyzed PRAMMO not only by a quality metric but also by simulating an fMRI experiment, which showed PRAMMO increased statistical significance in activated regions of interest over retrospective techniques in the “deliberate motion” case [32]. We subsequently confirmed these results in an actual fMRI experiment involving a breath-holding task [33]. One study by Speck et al showed that their optical correction system increases the number of activated voxels while decreasing both false positives and false negatives in an in-vivo visual fMRI paradigm [42].…”
Section: Discussionsupporting
confidence: 54%
See 1 more Smart Citation
“…Our previous study analyzed PRAMMO not only by a quality metric but also by simulating an fMRI experiment, which showed PRAMMO increased statistical significance in activated regions of interest over retrospective techniques in the “deliberate motion” case [32]. We subsequently confirmed these results in an actual fMRI experiment involving a breath-holding task [33]. One study by Speck et al showed that their optical correction system increases the number of activated voxels while decreasing both false positives and false negatives in an in-vivo visual fMRI paradigm [42].…”
Section: Discussionsupporting
confidence: 54%
“…Broadly speaking they can be classified into image-based methods [46] which can only correct for inter-volume movements, navigator-based methods [11], which acquire extra data along various three-dimensional k-space trajectories to estimate the 6-df [35,51,52,48,53], and marker-based methods which follow in real time the position of external markers attached to the head either by optical tracking [54,42,36,14,27] or using MRI [10,55,13,12,25,7,31,32]. Our group has developed prospective active-marker motion correction (PRAMMO) for structural [31] and echo-planar brain scans and demonstrated potential advantages of the approach for functional imaging [32,33]. However, our initial experiments were done assuming substantial and highly controlled motion as well as results reported for individual subjects.…”
Section: Introductionmentioning
confidence: 99%
“…However, in most of the brain these changes are typically smaller than partial volume and spin history motion effects, and for a relatively homogeneous coil both are likely to be smaller than the effect of motion on the phase-encode warping, which SimPACE does produce accurately. Furthermore, these can be accounted for or simulated retrospectively (Hartwig et al, 2011; Ooi et al, 2013; Xu et al, 2007), although this is outside the scope of the present study. Additionally, SimPACE does not produce within-slice acquisition motion or motion between excitation and completion of EPI readout and thus is limited to between-slice motion.…”
Section: Discussionmentioning
confidence: 99%
“…Thus, tissue movements between these short intervals reflect contiguous deformation in the cell sheet. To calculate deformation we apply differential image correlation techniques (36) using custom image processing programs [from the NIH ImageJ plug-in bUnwarpJ (37)]. Because this method uses betasplines the resulting deformations are "smooth."…”
Section: Methodsmentioning
confidence: 99%