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Relaxation effects in MRI-based quantification of fat content and fatty acid composition.

Peterson, Pernilla LU ; Svensson, Jonas LU and Månsson, Sven LU (2014) In Magnetic Resonance in Medicine 72(5). p.1320-1329
Abstract
Purpose: To investigate various sources of bias in MRI-based quantification of fat fraction (FF) and fatty acid composition (FAC) using chemical shift-encoded techniques. Methods: Signals from various FFs and FACs and individual relaxation rates of all signal components were simulated. From these signals, FF and FAC parameters were estimated with and without correction for differences in individual relaxation rates. In addition, phantom experiments were conducted with various flip angles and number of echoes to validate the simulations. Results: As expected, T1 weighting resulted in an overestimation of the FF, but had much smaller impact on the FAC parameters. Differences in T2 values of the signal components resulted in overestimation of... (More)
Purpose: To investigate various sources of bias in MRI-based quantification of fat fraction (FF) and fatty acid composition (FAC) using chemical shift-encoded techniques. Methods: Signals from various FFs and FACs and individual relaxation rates of all signal components were simulated. From these signals, FF and FAC parameters were estimated with and without correction for differences in individual relaxation rates. In addition, phantom experiments were conducted with various flip angles and number of echoes to validate the simulations. Results: As expected, T1 weighting resulted in an overestimation of the FF, but had much smaller impact on the FAC parameters. Differences in T2 values of the signal components resulted in overestimation of the FAC parameters in fat/water mixtures, whereas the estimation in pure oil was largely unaffected. This bias was corrected using a simplified signal model with different T2 values of water and fat, where the accuracy of the modeled T2 of water was critical. The results of the phantom experiment were in agreement with simulations. Conclusion: T1 weighting has only a minor effect on FAC quantification in both fat/water mixtures and pure oils. T2 weighting is mainly a concern in fat/water mixtures but may be corrected using a simplified model. Magn Reson Med, 2013. © 2013 Wiley Periodicals, Inc. (Less)
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organization
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type
Contribution to journal
publication status
published
subject
in
Magnetic Resonance in Medicine
volume
72
issue
5
pages
1320 - 1329
publisher
Wiley Online Library
external identifiers
  • pmid:24327547
  • wos:000343873900014
  • scopus:84907955447
ISSN
1522-2594
DOI
10.1002/mrm.25048
language
English
LU publication?
yes
id
6582f5dc-1a1b-4805-9610-59eafc503ced (old id 4224876)
alternative location
http://www.ncbi.nlm.nih.gov/pubmed/24327547?dopt=Abstract
date added to LUP
2014-01-04 12:17:38
date last changed
2017-04-30 04:04:50
@article{6582f5dc-1a1b-4805-9610-59eafc503ced,
  abstract     = {Purpose: To investigate various sources of bias in MRI-based quantification of fat fraction (FF) and fatty acid composition (FAC) using chemical shift-encoded techniques. Methods: Signals from various FFs and FACs and individual relaxation rates of all signal components were simulated. From these signals, FF and FAC parameters were estimated with and without correction for differences in individual relaxation rates. In addition, phantom experiments were conducted with various flip angles and number of echoes to validate the simulations. Results: As expected, T1 weighting resulted in an overestimation of the FF, but had much smaller impact on the FAC parameters. Differences in T2 values of the signal components resulted in overestimation of the FAC parameters in fat/water mixtures, whereas the estimation in pure oil was largely unaffected. This bias was corrected using a simplified signal model with different T2 values of water and fat, where the accuracy of the modeled T2 of water was critical. The results of the phantom experiment were in agreement with simulations. Conclusion: T1 weighting has only a minor effect on FAC quantification in both fat/water mixtures and pure oils. T2 weighting is mainly a concern in fat/water mixtures but may be corrected using a simplified model. Magn Reson Med, 2013. © 2013 Wiley Periodicals, Inc.},
  author       = {Peterson, Pernilla and Svensson, Jonas and Månsson, Sven},
  issn         = {1522-2594},
  language     = {eng},
  number       = {5},
  pages        = {1320--1329},
  publisher    = {Wiley Online Library},
  series       = {Magnetic Resonance in Medicine},
  title        = {Relaxation effects in MRI-based quantification of fat content and fatty acid composition.},
  url          = {http://dx.doi.org/10.1002/mrm.25048},
  volume       = {72},
  year         = {2014},
}