AUTHOR=Roat Sigrun , Vít Martin , Wampl Stefan , Schmid Albrecht Ingo , Laistler Elmar 

TITLE=A Flexible Array for Cardiac 31P MR Spectroscopy at 7 T

JOURNAL=Frontiers in Physics

VOLUME=8

YEAR=2020

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2020.00092

DOI=10.3389/fphy.2020.00092

ISSN=2296-424X

ABSTRACT=<p><bold>Purpose:</bold> The simulation optimization and implementation of a flexible <sup>31</sup>P transmit/receive coil array, under the geometrical constraint of fitting into the housing of an already existing 12-channel proton array, to enable localized cardiac <sup>31</sup>P MRS at 7 T is presented.</p><p><bold>Methods:</bold> The performance in terms of homogeneity, power and SAR efficiency, and receive benchmark of 32 potential array designs was compared by full wave 3D electromagnetic simulation considering the respective optimal static <inline-formula><mml:math id="M1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mrow><mml:mtext>B</mml:mtext></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo></mml:mrow></mml:msubsup></mml:math></inline-formula> shims. The design with the best performance was built and compared to a commercially available single loop in simulation and measurement.</p><p><bold>Results:</bold> Simulation revealed an optimal array design comprising three overlapping elements, each sized 94 × 141 mm<sup>2</sup>. Simulation comparison with a single loop coil predicted a performance increase due to increased power efficiency and lower SAR values. This was verified by phantom measurements, where an SNR increase of 46% could be observed for localized <sup>31</sup>P spectroscopy in a voxel positioned comparable to an <italic>in vivo</italic> cardiac measurement scenario.</p><p><bold>Conclusion:</bold> A flexible <sup>31</sup>P/<sup>1</sup>H RF coil array with improved SNR is presented, enabling localized <italic>in vivo</italic> cardiac <sup>31</sup>P spectroscopy at 7 T.</p>