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Calibration of RF transmitter voltages for hyperpolarized gas MRI
Author(s) -
Bashir Adil,
Conradi Mark S.,
Woods Jason C.,
Quirk James D.,
Yablonskiy Ddmitriy A.
Publication year - 2009
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.21821
Subject(s) - calibration , flip angle , nuclear magnetic resonance , magnetic resonance imaging , radio frequency , signal (programming language) , radiofrequency coil , materials science , chemistry , physics , computer science , medicine , radiology , telecommunications , quantum mechanics , programming language
MRI with hyperpolarized gases, 3 He, 129 Xe, 13 C, and others, has the potential to become an important diagnostic technique for clinical imaging. Due to the nonreversible loss of magnetization in hyperpolarized gas imaging, the choice of the flip angle is a major factor that influences the signal intensity, and hence, the signal‐to‐noise ratio. Conventional automated radiofrequency (RF) calibration procedures for 1 H imaging are not suitable for hyperpolarized gas imaging. Herein, we have demonstrated a simple procedure for RF calibration for magnetic resonance imaging (MRI) with hyperpolarized gases that is easily adaptable to clinical settings. We have demonstrated that there exists a linear relationship between the RF transmitter voltages required to obtain the same nutation angle for protons ( V 1H ) and hyperpolarized gas nuclei ( V 3He ). For our 1 H and 3 He coils we found that V 3He = 1.937 · V 1 H with correlation coefficient r 2 = 0.97. This calibration can be done as a one‐time procedure during the routine quality assurance (QA) protocol. The proposed procedure was found to be extremely robust in routine scanning and provided an efficient method to achieve a desired flip angle, thus allowing optimum image quality. Magn Reson Med 61:239–243, 2009. © 2008 Wiley‐Liss, Inc.