REST‐PEEP: reduced scan time phase‐encoded echo planar imaging

Guilfoyle, David N.; Hrabě, Jan

doi:10.1002/nbm.827

Cited by 4 publications

(2 citation statements)

References 20 publications

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“…During the past decade a number of studies have explored diffusion MRI’s capability of assaying fiber connectivity in post-mortem, fixed brains. Studies of various species, including the mouse (Mori et al, 2001; Guilfoyle et al, 2003; Sun et al, 2003; Zhang et al, 2003, 2005; D’Arceuil and de Crespigny, 2007), cat (Takahashi et al, 2010, 2011), pig (Dyrby et al, 2007, 2011), rabbit (D’Arceuil et al, 2008), baboon (Kroenke et al, 2005), macaque (D’Arceuil et al, 2007), and human (Roebroeck et al, 2008; Miller et al, 2011; Takahashi et al, 2012), have supported this approach as an effective method of identifying and observing development of fiber bundles. It has also been shown that the anisotropy of fixed tissue does not differ significantly compared to fresh tissue (Sun et al, 2003; D’Arceuil et al, 2007), and that fixed brain tissue retains its original diffusion property for at least 3 years (Dyrby et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

The Claustrum and Insula in Microcebus murinus: A High Resolution Diffusion Imaging Study

Park¹,

Tyszka²,

Allman³

2012

Front. Neuroanat.

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The claustrum and the insula are closely juxtaposed in the brain of the prosimian primate, the gray mouse lemur (Microcebus murinus). Whether the claustrum has closer affinities with the cortex or the striatum has been debated for many decades. Our observation of histological sections from primate brains and genomic data in the mouse suggest former. Given this, the present study compares the connections of the two structures in Microcebus using high angular resolution diffusion imaging (HARDI, with 72 directions), with a very small voxel size (90 micra), and probabilistic fiber tractography. High angular and spatial resolution diffusion imaging is non-destructive, requires no surgical interventions, and the connection of each and every voxel can be mapped, whereas in conventional tract tracer studies only a few specific injection sites can be assayed. Our data indicate that despite the high genetic and spatial affinities between the two structures, their connectivity patterns are very different. The claustrum connects with many cortical areas and the olfactory bulb; its strongest probabilistic connections are with the entorhinal cortex, suggesting that the claustrum may have a role in spatial memory and navigation. By contrast, the insula connects with many subcortical areas, including the brainstem and thalamic structures involved in taste and visceral feelings. Overall, the connections of the Microcebus claustrum and insula are similar to those of the rodents, cat, macaque, and human, validating our results. The insula in the Microcebus connects with the dorsolateral frontal cortex in contrast to the mouse insula, which has stronger connections with the ventromedial frontal lobe, yet this is consistent with the dorsolateral expansion of the frontal cortex in primates. In addition to revealing the connectivity patterns of the Microcebus brain, our study demonstrates that HARDI, at high resolutions, can be a valuable tool for mapping fiber pathways for multiple sites in fixed brains in rare and difficult-to-obtain species.

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Section: Introductionmentioning

confidence: 99%

The Claustrum and Insula in Microcebus murinus: A High Resolution Diffusion Imaging Study

Park¹,

Tyszka²,

Allman³

2012

Front. Neuroanat.

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“…Interleaved imaging approaches employing segmented k ‐space acquisitions (10) can be advantageously combined with EVI. When spatial resolution and matrix size are kept constant, interleaving allows T EC to be significantly reduced and the voxel bandwidth to be correspondingly increased, although temporal resolution is compromised.…”

Section: Theorymentioning

confidence: 99%

Improved echo volumar imaging (EVI) for functional MRI

Zwaag

Francis

Bowtell

2006

Magnetic Resonance in Med

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Echo volumar imaging (EVI) is a 3D modification of echo-planar imaging (EPI) that allows data from an entire volume to be acquired following a single RF excitation. EVI provides a high rate of volumar data acquisition, which is advantageous for functional MRI (fMRI). However, few studies to date have applied EVI to fMRI, since because of gradient hardware limitations EVI generally has to be used with long sampling times, resulting in high sensitivity to susceptibility-induced distortions. In this study we modified the EVI sequence to improve its suitability for fMRI. The sampling time is reduced by the use of a high gradient-switching frequency, a small number of echoes, and outer volume suppression (OVS); rewind gradients ameliorate Nyquist ghosting; and phase correction via a calibration scan reduces ghosting and distortion. It is shown that the modified EVI sequence allows fMRI data to be acquired with a temporal resolution of 167 ms. Magn Reson Med 56: 1320 -1327, 2006.

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REST‐PEEP: reduced scan time phase‐encoded echo planar imaging

Guilfoyle

Hrabě

2003

NMR in Biomedicine

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Echo planar methodology can be used for rapid acquisition in three dimensions of k-space. There are two groups of sequences which have thus far been implemented. The first group is characterized by three-dimensional acquisition from a single RF excitation. Echo planar shift mapping and echo volume imaging are single-shot chemical shift imaging and three-dimensional spatial imaging techniques, respectively. Even though these methods are extremely fast, their spatial and spectral resolutions are poor. In the second group of sequences, echo planar imaging acquisition is repeated for every phase-encode gradient step to improve upon the spatial resolution and signal-to-noise ratio at the expense of acquisition time. Here we report a novel combination of these two groups of sequences aimed at providing additional flexibility in trade-offs between the spectral bandwidth, signal-to-noise ratio, spatial resolution and imaging time. Preliminary results for both chemical shift imaging and three-dimensional spatial imaging are presented. The chemical shift imaging was optimized for excitation of the N-acetyl aspartate (NAA). An interesting consequence of our approach is that the Nyquist ghost is transferred from the spectrum to the metabolite image.

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REST‐PEEP: reduced scan time phase‐encoded echo planar imaging

Cited by 4 publications

References 20 publications

The Claustrum and Insula in Microcebus murinus: A High Resolution Diffusion Imaging Study

The Claustrum and Insula in Microcebus murinus: A High Resolution Diffusion Imaging Study

Improved echo volumar imaging (EVI) for functional MRI

REST‐PEEP: reduced scan time phase‐encoded echo planar imaging

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