Abstract:
PURPOSE:To illustrate the potential bias caused by imaging gradients in correlation MRI sequences using longitudinal magnetization storage (LS) and examine the case of filter exchange imaging (FEXI) yielding maps of the apparent exchange rate (AXR). METHODS:The effects of imaging gradients in FEXI were observed on yeast cells. To analyze the AXR bias, signal evolution was calculated by applying matrix exponential operators. RESULTS:A sharp threshold for the slice thickness was identified, below which the AXR is increasingly underestimated. The bias can be understood in terms of an extended low-pass diffusion filtering during the LS interval, which is more pronounced at lower exchange rates. For a total exchange rate constant larger than 1 s-1 , the AXR bias is expected to be negligible when slices thicker than 2.5 mm are used. CONCLUSION:In correlation experiments like FEXI, relying on LS with variable duration, imaging gradients may cause disrupting effects that cannot be easily mitigated and should be carefully considered for unbiased results. In typical clinical applications of FEXI, the imaging gradients are expected to cause a negligible AXR bias. However, the AXR bias may be significant in preclinical settings or whenever thin imaging slices are used. Magn Reson Med 79:2228-2235, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Lasič S,Lundell H,Topgaard D,Dyrby TBdoi
10.1002/mrm.26856subject
Has Abstractpub_date
2018-04-01 00:00:00pages
2228-2235issue
4eissn
0740-3194issn
1522-2594journal_volume
79pub_type
杂志文章abstract::Parallel transmission has emerged as an efficient means for implementing multidimensional spatially selective radiofrequency excitation pulses. To date, most theoretical and experimental work on parallel transmission radiofrequency (RF) pulse design is based on the small-tip-angle approximation to the Bloch equation. ...
journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.22827
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abstract:PURPOSE:To achieve rapid, high resolution whole-brain gray matter (GM) imaging by developing a novel, single-slab three-dimensional dual-echo fast-spin-echo pulse sequence and GM-selective reconstruction. METHODS:Unlike conventional GM imaging that uses time-consuming double-inversion-recovery preparation, the propose...
journal_title:Magnetic resonance in medicine
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journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.1910340111
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journal_title:Magnetic resonance in medicine
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journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.25465
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journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
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journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.1910350217
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journal_title:Magnetic resonance in medicine
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journal_title:Magnetic resonance in medicine
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journal_title:Magnetic resonance in medicine
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journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.22697
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journal_title:Magnetic resonance in medicine
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journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.24873
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journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/(sici)1522-2594(199905)41:5<1058::aid-mrm2
更新日期:1999-05-01 00:00:00
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doi:10.1002/mrm.21822
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journal_title:Magnetic resonance in medicine
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更新日期:2012-06-01 00:00:00
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journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910290320
更新日期:1993-03-01 00:00:00
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journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910350207
更新日期:1996-02-01 00:00:00
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journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.23276
更新日期:2012-09-01 00:00:00
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journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910370219
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journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
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journal_title:Magnetic resonance in medicine
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journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.1910250109
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pub_type: 杂志文章
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更新日期:2014-07-01 00:00:00
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journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
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journal_title:Magnetic resonance in medicine
pub_type: 杂志文章
doi:10.1002/mrm.1910290105
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journal_title:Magnetic resonance in medicine
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doi:10.1002/mrm.22011
更新日期:2009-08-01 00:00:00
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journal_title:Magnetic resonance in medicine
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journal_title:Magnetic resonance in medicine
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journal_title:Magnetic resonance in medicine
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