TY - JOUR
T1 - Magnetic field strength dependent SNR gain at the center of a spherical phantom and up to 11.7T
AU - Le Ster, Caroline
AU - Grant, Andrea
AU - Van de Moortele, Pierre-François
AU - Monreal-Madrigal, Alejandro
AU - Adriany, Gregor
AU - Vignaud, Alexandre
AU - Mauconduit, Franck
AU - Rabrait-Lerman, Cécile
AU - Poser, Benedikt A.
AU - Uğurbil, Kâmil
AU - Boulant, Nicolas
N1 - © 2022 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine.
PY - 2022/11
Y1 - 2022/11
N2 - PURPOSE: The SNR at the center of a spherical phantom of known electrical properties was measured in quasi-identical experimental conditions as a function of magnetic field strength between 3 T and 11.7 T.METHODS: The SNR was measured at the center of a spherical water saline phantom with a gradient recalled echo sequence. Measurements were performed at NeuroSpin at 3, 7, and 11.7 T. The phantom was then shipped to Maastricht University and then to the University of Minnesota for additional data points at 7, 9.4, and 10.5 T. Experiments were carried out with the exact same type of birdcage volume coil (except at 3 T, where a similar coil was used) to attempt at isolating the evolution of SNR with field strength alone. Phantom electrical properties were characterized over the corresponding frequency range.RESULTS: Electrical properties were found to barely vary over the frequency range. Removing the influence of the flip-angle excitation inhomogeneity was crucial, as expected. After such correction, measurements revealed a gain of SNR growing as B0 1.94 ± 0.16 compared with B0 2.13 according to ultimate intrinsic SNR theory.CONCLUSIONS: By using quasi-identical experimental setups (RF volume coil, phantom, electrical properties, and protocol), this work reports experimental data between 3 T and 11.7 T, enabling the comparison with SNR theories in which conductivity and permittivity can be assumed to be constant with respect to field strength. According to ultimate SNR theory, these results can be reasonably extrapolated to the performance of receive arrays with greater than about 32 elements for central SNR in the same spherical phantom.
AB - PURPOSE: The SNR at the center of a spherical phantom of known electrical properties was measured in quasi-identical experimental conditions as a function of magnetic field strength between 3 T and 11.7 T.METHODS: The SNR was measured at the center of a spherical water saline phantom with a gradient recalled echo sequence. Measurements were performed at NeuroSpin at 3, 7, and 11.7 T. The phantom was then shipped to Maastricht University and then to the University of Minnesota for additional data points at 7, 9.4, and 10.5 T. Experiments were carried out with the exact same type of birdcage volume coil (except at 3 T, where a similar coil was used) to attempt at isolating the evolution of SNR with field strength alone. Phantom electrical properties were characterized over the corresponding frequency range.RESULTS: Electrical properties were found to barely vary over the frequency range. Removing the influence of the flip-angle excitation inhomogeneity was crucial, as expected. After such correction, measurements revealed a gain of SNR growing as B0 1.94 ± 0.16 compared with B0 2.13 according to ultimate intrinsic SNR theory.CONCLUSIONS: By using quasi-identical experimental setups (RF volume coil, phantom, electrical properties, and protocol), this work reports experimental data between 3 T and 11.7 T, enabling the comparison with SNR theories in which conductivity and permittivity can be assumed to be constant with respect to field strength. According to ultimate SNR theory, these results can be reasonably extrapolated to the performance of receive arrays with greater than about 32 elements for central SNR in the same spherical phantom.
KW - ARRAY
KW - MRI
KW - PATTERNS
KW - POWER
KW - SENSITIVITY
KW - TO-NOISE-RATIO
KW - field strength
KW - signal-to-noise ratio
KW - volume coil
U2 - 10.1002/mrm.29391
DO - 10.1002/mrm.29391
M3 - Article
C2 - 35849739
SN - 0740-3194
VL - 88
SP - 2131
EP - 2138
JO - Magnetic Resonance in Medicine
JF - Magnetic Resonance in Medicine
IS - 5
ER -