7T Rf coils: cross site comparison of sTx and pTx

Should I do 7T fMRI with the pTx or sTx coil? Consider the difference in geometry Renzo Huber1, A. Tyler Morgan1, Alessandra Pizzuti2, Benedikt Poser2, Barbara Dymerska3, Dario Bosch4, Yuhui Chai5, Natalia Gudino1, Joelle Sarlls1, Sebastian Dresbach2,6, Joseph (An Thanh) Vu7, Jen Evans1, Salvatore Torrisi7, Rüdiger Stirnberg8, Monique Tourell9, Saskia Bollmann9, Luca Vizioli10, Essa Yacoub10, Nikos Priovoulos11, Emma Brouwer11, Wietske van der Zwaag11, Hendrik Mattern12, Daniel Gomez13, Anna Blazejewska13, Jonathan R. Polimeni13, Peter Bandettini1 1.NIH, Bethesda, USA, 2.Maastricht University, Netherlands, 3.UCL, London, UK, 4.MPI for Biol. Cybernetics, Tübingen, Germany, 5.University of Illinois Urbana-Champaign, USA, 6.MPI Leipzig, Germany, 7.UCSF, VA, USA, 8.DZNE Bonn, Germany, 9.University of Queensland, Australia, 10.CMRR, Minneapolis, USA, 11.Spinoza Centre for Neuroimaging, Amsterdam, Netherlands, 12.BMMR OVGU Magdeburg, Germany, 13.Martinos Center, MGB, USA Abstract Motivation: Parallel transmit (pTx) coils at 7T are clinically approved, but their advantage for fMRI remains unclear. Goal: We aimed to determine whether widely-used sTx or pTx coils provide better 7T fMRI data. Approach: We investigated 30 coils across 15 7T sites (SIEMENS and Philips), estimating noise correlation across receivers and mapped transmit field size/location using MR-visible beeswax and CT scans. Results: pTx coil placement benefits lower brain areas but increases noise coupling. Nova sTx and pTx coils differ in geometry. Impact: Geometrical design choices play a surprisingly large role for 7T fMRI when choosing the optimal coil.