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Characterization and optimization of the visualization performance of continuous flow overhauser DNP hyperpolarized water MRI: Inversion recovery approach
Author(s) -
Terekhov Maxim,
Krummenacker Jan,
Denysenkov Vasyl,
Gerz Kathrin,
Prisner Thomas,
Schreiber Laura Maria
Publication year - 2016
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.25574
Subject(s) - hyperpolarization (physics) , nuclear magnetic resonance , magnetization , relaxation (psychology) , pulse sequence , chemistry , materials science , magnetic field , physics , nuclear magnetic resonance spectroscopy , psychology , social psychology , quantum mechanics
Purpose Overhauser dynamic nuclear polarization (DNP) allows the production of liquid hyperpolarized substrate inside the MRI magnet bore as well as its administration in continuous flow mode to acquire MR images with enhanced signal‐to‐noise ratio. We implemented inversion recovery preparation in order to improve contrast‐to‐noise ratio and to quantify the overall imaging performance of Overhauser DNP‐enhanced MRI. Method The negative enhancement created by DNP in combination with inversion recovery (IR) preparation allows canceling selectively the signal originated from Boltzmann magnetization and visualizing only hyperpolarized fluid. The theoretical model describing gain of MR image intensity produced by steady‐state continuous flow DNP hyperpolarized magnetization was established and proved experimentally. Results A precise quantification of signal originated purely from DNP hyperpolarization was achieved. A temperature effect on longitudinal relaxation had to be taken into account to fit experimental results with numerical prediction. Conclusion Using properly adjusted IR preparation, the complete zeroing of thermal background magnetization was achieved, providing an essential increase of contrast‐to‐noise ratio of DNP‐hyperpolarized water images. To quantify and optimize the steady‐state conditions for MRI with continuous flow DNP, an approach similar to that incorporating transient‐state thermal magnetization equilibrium in spoiled fast field echo imaging sequences can be used. Magn Reson Med 75:985–996, 2016. © 2015 Wiley Periodicals, Inc.