Distortion and signal loss in medial temporal lobe.

<h4>Background</h4>The medial temporal lobe (MTL) contains subregions that are subject to severe distortion and signal loss in functional MRI. Air/tissue and bone/tissue interfaces in the vicinity of the MTL distort the local magnetic field due to differences in magnetic susceptibility....

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Autores principales:	Cheryl A Olman, Lila Davachi, Souheil Inati
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2009
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/5105dd0600804f9288e4ca078767afb4
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spelling	oai:doaj.org-article:5105dd0600804f9288e4ca078767afb42021-11-25T06:27:37ZDistortion and signal loss in medial temporal lobe.1932-620310.1371/journal.pone.0008160https://doaj.org/article/5105dd0600804f9288e4ca078767afb42009-12-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/19997633/pdf/?tool=EBIhttps://doaj.org/toc/1932-6203<h4>Background</h4>The medial temporal lobe (MTL) contains subregions that are subject to severe distortion and signal loss in functional MRI. Air/tissue and bone/tissue interfaces in the vicinity of the MTL distort the local magnetic field due to differences in magnetic susceptibility. Fast image acquisition and thin slices can reduce the amount of distortion and signal loss, but at the cost of image signal-to-noise ratio (SNR).<h4>Methodology/principal findings</h4>In this paper, we quantify the severity of distortion and signal loss in MTL subregions for three different echo planar imaging (EPI) acquisitions at 3 Tesla: a conventional moderate-resolution EPI (3x3x3 mm), a conventional high-resolution EPI (1.5x1.5x2 mm), and a zoomed high-resolution EPI. We also demonstrate the advantage of reversing the phase encode direction to control the direction of distortion and to maximize efficacy of distortion compensation during data post-processing. With the high-resolution zoomed acquisition, distortion is not significant and signal loss is present only in the most anterior regions of the parahippocampal gyrus. Furthermore, we find that the severity of signal loss is variable across subjects, with some subjects showing negligible loss and others showing more dramatic loss.<h4>Conclusions/significance</h4>Although both distortion and signal loss are minimized in a zoomed field of view acquisition with thin slices, this improvement in accuracy comes at the cost of reduced SNR. We quantify this trade-off between distortion and SNR in order to provide a decision tree for design of high-resolution experiments investigating the function of subregions in MTL.Cheryl A OlmanLila DavachiSouheil InatiPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 4, Iss 12, p e8160 (2009)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Cheryl A Olman Lila Davachi Souheil Inati Distortion and signal loss in medial temporal lobe.
description	<h4>Background</h4>The medial temporal lobe (MTL) contains subregions that are subject to severe distortion and signal loss in functional MRI. Air/tissue and bone/tissue interfaces in the vicinity of the MTL distort the local magnetic field due to differences in magnetic susceptibility. Fast image acquisition and thin slices can reduce the amount of distortion and signal loss, but at the cost of image signal-to-noise ratio (SNR).<h4>Methodology/principal findings</h4>In this paper, we quantify the severity of distortion and signal loss in MTL subregions for three different echo planar imaging (EPI) acquisitions at 3 Tesla: a conventional moderate-resolution EPI (3x3x3 mm), a conventional high-resolution EPI (1.5x1.5x2 mm), and a zoomed high-resolution EPI. We also demonstrate the advantage of reversing the phase encode direction to control the direction of distortion and to maximize efficacy of distortion compensation during data post-processing. With the high-resolution zoomed acquisition, distortion is not significant and signal loss is present only in the most anterior regions of the parahippocampal gyrus. Furthermore, we find that the severity of signal loss is variable across subjects, with some subjects showing negligible loss and others showing more dramatic loss.<h4>Conclusions/significance</h4>Although both distortion and signal loss are minimized in a zoomed field of view acquisition with thin slices, this improvement in accuracy comes at the cost of reduced SNR. We quantify this trade-off between distortion and SNR in order to provide a decision tree for design of high-resolution experiments investigating the function of subregions in MTL.
format	article
author	Cheryl A Olman Lila Davachi Souheil Inati
author_facet	Cheryl A Olman Lila Davachi Souheil Inati
author_sort	Cheryl A Olman
title	Distortion and signal loss in medial temporal lobe.
title_short	Distortion and signal loss in medial temporal lobe.
title_full	Distortion and signal loss in medial temporal lobe.
title_fullStr	Distortion and signal loss in medial temporal lobe.
title_full_unstemmed	Distortion and signal loss in medial temporal lobe.
title_sort	distortion and signal loss in medial temporal lobe.
publisher	Public Library of Science (PLoS)
publishDate	2009
url	https://doaj.org/article/5105dd0600804f9288e4ca078767afb4
work_keys_str_mv	AT cherylaolman distortionandsignallossinmedialtemporallobe AT liladavachi distortionandsignallossinmedialtemporallobe AT souheilinati distortionandsignallossinmedialtemporallobe
_version_	1718413680070098944

Distortion and signal loss in medial temporal lobe.

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