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T 2 * Measurement bias due to concomitant gradient fields
Author(s) -
Hofstetter Lorne W.,
Morrell Glen,
Kaggie Joshua,
Kim Daniel,
Carlston Kristi,
Lee Vivian S.
Publication year - 2017
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.26240
Subject(s) - imaging phantom , dephasing , concomitant , relaxometry , magnetic resonance imaging , amplitude , nuclear magnetic resonance , physics , computer science , biomedical engineering , medicine , mathematics , radiology , optics , spin echo , statistics , condensed matter physics
Purpose To demonstrate that concomitant magnetic fields can cause significant spatially dependent biases inT 2 *relaxometry measurements with implications for clinical applications such as BOLD and dynamic susceptibility contrast‐enhanced MRI. Theory and Methods After developing a theoretical framework for intravoxel dephasing and signal loss from concomitant magnetic fields, this framework and the effect of concomitant fields onT 2 *are validated with phantom experiments and numerical simulation. In lower leg and renalT 2 *mapping, we quantify measurement bias for imaging protocols with high gradient amplitude multiecho readouts, comparable to those used in clinical applications. Results Concordance between phantom experiment and numerical simulation validate the theoretical framework. Changes inT 2 *measured in the lower leg and kidney varied by up to 15% and 35%, respectively, as a result of concomitant gradient effects when compared with the control measurements. Conclusion Concomitant magnetic fields produced by imaging gradient coils can cause clinically significantT 2 *mapping errors when high amplitude, long duration gradient waveforms are used. While we have shown that measurement biases can be quite large, modification of imaging parameters can potentially reduce concomitant field‐induced measurement errors to acceptable levels. Magn Reson Med 77:1562–1572, 2017. © 2016 International Society for Magnetic Resonance in Medicine