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MRI-Based Quantification of Magnetic Susceptibility in Gel Phantoms : Assessment of Measurement and Calculation Accuracy

Olsson, Emma LU ; Wirestam, Ronnie LU and Lind, Emelie LU (2018) In Radiology research and practice 2018.
Abstract

The local magnetic field inside and around an object in a magnetic resonance imaging unit depends on the magnetic susceptibility of the object being magnetized, in combination with its geometry/orientation. Magnetic susceptibility can thus be exploited as a source of tissue contrast, and susceptibility imaging may also become a useful tool in contrast agent quantification and for assessment of venous oxygen saturation levels. In this study, the accuracy of an established procedure for quantitative susceptibility mapping (QSM) was investigated. Three gel phantoms were constructed with cylinders of varying susceptibility and geometry. Experimental results were compared with simulated and analytically calculated data. An expected linear... (More)

The local magnetic field inside and around an object in a magnetic resonance imaging unit depends on the magnetic susceptibility of the object being magnetized, in combination with its geometry/orientation. Magnetic susceptibility can thus be exploited as a source of tissue contrast, and susceptibility imaging may also become a useful tool in contrast agent quantification and for assessment of venous oxygen saturation levels. In this study, the accuracy of an established procedure for quantitative susceptibility mapping (QSM) was investigated. Three gel phantoms were constructed with cylinders of varying susceptibility and geometry. Experimental results were compared with simulated and analytically calculated data. An expected linear relationship between estimated susceptibility and concentration of contrast agent was observed. Less accurate QSM-based susceptibility values were observed for cylindrical objects at angles, relative to the main magnetic field, that were close to or larger than the magic angle. Results generally improved for large objects/high spatial resolution and large volume coverage. For simulated phase maps, accurate susceptibility quantification by QSM was achieved also for more challenging geometries. The investigated QSM algorithm was generally robust to changes in measurement and calculation parameters, but experimental phase data of sufficient quality may be difficult to obtain in certain geometries.

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type
Contribution to journal
publication status
published
subject
in
Radiology research and practice
volume
2018
article number
6709525
publisher
Hindawi Limited
external identifiers
  • pmid:30155300
ISSN
2090-1941
DOI
10.1155/2018/6709525
language
English
LU publication?
yes
id
079d3df0-93f2-4b8d-b72b-c8ac8306b391
date added to LUP
2019-05-22 13:03:20
date last changed
2019-12-18 02:40:26
@article{079d3df0-93f2-4b8d-b72b-c8ac8306b391,
  abstract     = {<p>The local magnetic field inside and around an object in a magnetic resonance imaging unit depends on the magnetic susceptibility of the object being magnetized, in combination with its geometry/orientation. Magnetic susceptibility can thus be exploited as a source of tissue contrast, and susceptibility imaging may also become a useful tool in contrast agent quantification and for assessment of venous oxygen saturation levels. In this study, the accuracy of an established procedure for quantitative susceptibility mapping (QSM) was investigated. Three gel phantoms were constructed with cylinders of varying susceptibility and geometry. Experimental results were compared with simulated and analytically calculated data. An expected linear relationship between estimated susceptibility and concentration of contrast agent was observed. Less accurate QSM-based susceptibility values were observed for cylindrical objects at angles, relative to the main magnetic field, that were close to or larger than the magic angle. Results generally improved for large objects/high spatial resolution and large volume coverage. For simulated phase maps, accurate susceptibility quantification by QSM was achieved also for more challenging geometries. The investigated QSM algorithm was generally robust to changes in measurement and calculation parameters, but experimental phase data of sufficient quality may be difficult to obtain in certain geometries.</p>},
  author       = {Olsson, Emma and Wirestam, Ronnie and Lind, Emelie},
  issn         = {2090-1941},
  language     = {eng},
  publisher    = {Hindawi Limited},
  series       = {Radiology research and practice},
  title        = {MRI-Based Quantification of Magnetic Susceptibility in Gel Phantoms : Assessment of Measurement and Calculation Accuracy},
  url          = {http://dx.doi.org/10.1155/2018/6709525},
  doi          = {10.1155/2018/6709525},
  volume       = {2018},
  year         = {2018},
}