Quantitative R<inf>2</inf>* MRI of the liver with rician noise models for evaluation of hepatic iron overload: Simulation, phantom, and early clinical experience

Takeshi Yokoo, Qing Yuan, Julien Sénégas, Andrea J. Wiethoff, Ivan Pedrosa

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Purpose: To compare Rician and non-Rician noise models for quantitative R<inf>2</inf>* magnetic resonance imaging (MRI), in a simulation, phantom, and human study. Materials and Methods: Synthetic 12-echo spoiled GRE (SGRE) datasets were generated with various R<inf>2</inf>* rates (0-2000 sec<sup>-1</sup>) at a signal-to-noise ratio (SNR) of 50, 20, 10, and 5. Phantoms of different MnCl<inf>2</inf> concentrations (0-25 mM) were constructed and imaged using a 12-echo 3D SGRE sequence at 1.5T. Increasing levels of synthetic noise was added to the original data to simulate sequentially lower SNR conditions. Sixteen patients with suspected or known iron overload were imaged using 12-echo 3D SGRE at 1.5T. Various R<inf>2</inf>* quantification methods, based on Rician and non-Rician noise models, were compared in the simulation, phantom, and human datasets. Results: Non-Rician R<inf>2</inf>* estimates were variably inaccurate in the high R<inf>2</inf>* range (>500 sec<sup>-1</sup>), with SNR-dependent linear goodness-of-fit statistic (R<sup>2</sup>) of 0.373-0.999. Rician R<inf>2</inf>* estimates were accurate even in the high R<inf>2</inf>* range, with high R<sup>2</sup> of 0.940-0.999 regardless of SNR. Non-Rician R<inf>2</inf>* estimates were variably nonlinear at high MnCl<inf>2</inf> concentrations, with SNR-dependent R<sup>2</sup> of 0.345-0.994. Rician R<inf>2</inf>* estimates were linear even at high MnCl<inf>2</inf> concentrations, with high R<sup>2</sup> of 0.923-0.994 regardless of SNR. Between-method agreement of the R<inf>2</inf>* estimates was excellent in patients with low ferritin but poor in patients with high ferritin. Rician R<inf>2</inf>* estimates had excellent correlation with ferritin (r = 0.966 P < 0.001). Conclusion: Rician R<inf>2</inf>* estimates were most consistent in the high R<inf>2</inf>* conditions and under varying SNR, and may be more reliable when high iron load is suspected.

Original languageEnglish (US)
JournalJournal of Magnetic Resonance Imaging
DOIs
StateAccepted/In press - 2015

Fingerprint

Iron Overload
Signal-To-Noise Ratio
Noise
Magnetic Resonance Imaging
Liver
Ferritins
Iron
manganese chloride

Keywords

  • mapping
  • Iron overload
  • Liver iron
  • mapping
  • R<inf>2</inf>
  • Rician noise
  • T<inf>2</inf>

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

Cite this

@article{c578cd5655704748920ba9e5584c61f9,
title = "Quantitative R2* MRI of the liver with rician noise models for evaluation of hepatic iron overload: Simulation, phantom, and early clinical experience",
abstract = "Purpose: To compare Rician and non-Rician noise models for quantitative R2* magnetic resonance imaging (MRI), in a simulation, phantom, and human study. Materials and Methods: Synthetic 12-echo spoiled GRE (SGRE) datasets were generated with various R2* rates (0-2000 sec-1) at a signal-to-noise ratio (SNR) of 50, 20, 10, and 5. Phantoms of different MnCl2 concentrations (0-25 mM) were constructed and imaged using a 12-echo 3D SGRE sequence at 1.5T. Increasing levels of synthetic noise was added to the original data to simulate sequentially lower SNR conditions. Sixteen patients with suspected or known iron overload were imaged using 12-echo 3D SGRE at 1.5T. Various R2* quantification methods, based on Rician and non-Rician noise models, were compared in the simulation, phantom, and human datasets. Results: Non-Rician R2* estimates were variably inaccurate in the high R2* range (>500 sec-1), with SNR-dependent linear goodness-of-fit statistic (R2) of 0.373-0.999. Rician R2* estimates were accurate even in the high R2* range, with high R2 of 0.940-0.999 regardless of SNR. Non-Rician R2* estimates were variably nonlinear at high MnCl2 concentrations, with SNR-dependent R2 of 0.345-0.994. Rician R2* estimates were linear even at high MnCl2 concentrations, with high R2 of 0.923-0.994 regardless of SNR. Between-method agreement of the R2* estimates was excellent in patients with low ferritin but poor in patients with high ferritin. Rician R2* estimates had excellent correlation with ferritin (r = 0.966 P < 0.001). Conclusion: Rician R2* estimates were most consistent in the high R2* conditions and under varying SNR, and may be more reliable when high iron load is suspected.",
keywords = "mapping, Iron overload, Liver iron, mapping, R<inf>2</inf>, Rician noise, T<inf>2</inf>",
author = "Takeshi Yokoo and Qing Yuan and Julien S{\'e}n{\'e}gas and Wiethoff, {Andrea J.} and Ivan Pedrosa",
year = "2015",
doi = "10.1002/jmri.24948",
language = "English (US)",
journal = "Journal of Magnetic Resonance Imaging",
issn = "1053-1807",
publisher = "John Wiley and Sons Inc.",

}

TY - JOUR

T1 - Quantitative R2* MRI of the liver with rician noise models for evaluation of hepatic iron overload

T2 - Simulation, phantom, and early clinical experience

AU - Yokoo, Takeshi

AU - Yuan, Qing

AU - Sénégas, Julien

AU - Wiethoff, Andrea J.

AU - Pedrosa, Ivan

PY - 2015

Y1 - 2015

N2 - Purpose: To compare Rician and non-Rician noise models for quantitative R2* magnetic resonance imaging (MRI), in a simulation, phantom, and human study. Materials and Methods: Synthetic 12-echo spoiled GRE (SGRE) datasets were generated with various R2* rates (0-2000 sec-1) at a signal-to-noise ratio (SNR) of 50, 20, 10, and 5. Phantoms of different MnCl2 concentrations (0-25 mM) were constructed and imaged using a 12-echo 3D SGRE sequence at 1.5T. Increasing levels of synthetic noise was added to the original data to simulate sequentially lower SNR conditions. Sixteen patients with suspected or known iron overload were imaged using 12-echo 3D SGRE at 1.5T. Various R2* quantification methods, based on Rician and non-Rician noise models, were compared in the simulation, phantom, and human datasets. Results: Non-Rician R2* estimates were variably inaccurate in the high R2* range (>500 sec-1), with SNR-dependent linear goodness-of-fit statistic (R2) of 0.373-0.999. Rician R2* estimates were accurate even in the high R2* range, with high R2 of 0.940-0.999 regardless of SNR. Non-Rician R2* estimates were variably nonlinear at high MnCl2 concentrations, with SNR-dependent R2 of 0.345-0.994. Rician R2* estimates were linear even at high MnCl2 concentrations, with high R2 of 0.923-0.994 regardless of SNR. Between-method agreement of the R2* estimates was excellent in patients with low ferritin but poor in patients with high ferritin. Rician R2* estimates had excellent correlation with ferritin (r = 0.966 P < 0.001). Conclusion: Rician R2* estimates were most consistent in the high R2* conditions and under varying SNR, and may be more reliable when high iron load is suspected.

AB - Purpose: To compare Rician and non-Rician noise models for quantitative R2* magnetic resonance imaging (MRI), in a simulation, phantom, and human study. Materials and Methods: Synthetic 12-echo spoiled GRE (SGRE) datasets were generated with various R2* rates (0-2000 sec-1) at a signal-to-noise ratio (SNR) of 50, 20, 10, and 5. Phantoms of different MnCl2 concentrations (0-25 mM) were constructed and imaged using a 12-echo 3D SGRE sequence at 1.5T. Increasing levels of synthetic noise was added to the original data to simulate sequentially lower SNR conditions. Sixteen patients with suspected or known iron overload were imaged using 12-echo 3D SGRE at 1.5T. Various R2* quantification methods, based on Rician and non-Rician noise models, were compared in the simulation, phantom, and human datasets. Results: Non-Rician R2* estimates were variably inaccurate in the high R2* range (>500 sec-1), with SNR-dependent linear goodness-of-fit statistic (R2) of 0.373-0.999. Rician R2* estimates were accurate even in the high R2* range, with high R2 of 0.940-0.999 regardless of SNR. Non-Rician R2* estimates were variably nonlinear at high MnCl2 concentrations, with SNR-dependent R2 of 0.345-0.994. Rician R2* estimates were linear even at high MnCl2 concentrations, with high R2 of 0.923-0.994 regardless of SNR. Between-method agreement of the R2* estimates was excellent in patients with low ferritin but poor in patients with high ferritin. Rician R2* estimates had excellent correlation with ferritin (r = 0.966 P < 0.001). Conclusion: Rician R2* estimates were most consistent in the high R2* conditions and under varying SNR, and may be more reliable when high iron load is suspected.

KW - mapping

KW - Iron overload

KW - Liver iron

KW - mapping

KW - R<inf>2</inf>

KW - Rician noise

KW - T<inf>2</inf>

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DO - 10.1002/jmri.24948

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