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A thermally polarized 129 Xe phantom for quality assurance in multi‐center hyperpolarized gas MRI studies
Author(s) -
Bier Elianna A.,
Nouls John C.,
Wang Ziyi,
He Mu,
Schrank Geoff,
MoralesMediomi,
Hashoian Ralph,
Svetlik Harvey,
Mugler John P.,
Driehuys Bastiaan
Publication year - 2019
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.27836
Subject(s) - imaging phantom , xenon , radiofrequency coil , materials science , flip angle , scanner , nuclear magnetic resonance , magnetic resonance imaging , nuclear medicine , electromagnetic coil , biomedical engineering , optics , physics , atomic physics , medicine , quantum mechanics , radiology
Purpose Hyperpolarized 129 Xe MR is increasingly being adopted worldwide, but no standards exist for assessing or comparing performance at different 129 Xe imaging centers. Therefore, we sought to develop a thermally polarized xenon phantom assembly, approximating the size of a human torso, along with an associated imaging protocol to enable rapid quality‐assurance imaging. Methods MR‐compatible pressure vessels, with an internal volume of 5.85 L, were constructed from pressure‐rated, engineering grade PE4710 high‐density polyethylene. They were filled with a mixture of 61% natural xenon and 39% oxygen to approximately 11.6 bar and placed in a loader shell filled with a 0.56% saline solution to mimic the human chest. Imaging employed a 2D spoiled gradient‐echo sequence using non‐slice‐selective excitation (TR/TE = 750/6.13 ms, flip angle = 74°, FOV = 40 × 440 mm, matrix = 64 × 32, bandwidth = 30 Hz/pixel, averages = 4), resulting in a 1.6 min acquisition. System characterization and imaging were performed at 8 different MRI centers. Results At 3 Telsa, 129 Xe in the pressure vessels was characterized by T 1 = 580.5 ± 8.3 ms, linewidth = 0.21 ppm, and chemical shift = +10.2 ppm. The phantom assembly was used to obtain transmit voltage calibrations and 2D and 3D images across multiple coil and scanner configurations at 8 sites. Across the 5 sites that employed a standard flexible chest coil, the SNR was 12.4 ± 1.8. Conclusion The high‐density polyethylene pressure vessels filled with thermally polarized xenon and associated loader shell combine to form a phantom assembly that enables spectroscopic and imaging acquisitions that can be used for testing, quality assurance, and performance tracking—capabilities essential for standardizing hyperpolarized 129 Xe MRI within and across institutions.