Stacked magnetic resonators for MRI RF coils decoupling

International audienceParallel transmission is a very promising method to tackle B 1 + field inhomogeneities at ultrahigh field in magnetic resonant imaging (MRI). This technique is however limited by the mutual coupling between the radiating elements. Here we propose to solve this problem by designing a passive magneto-electric resonator that we here refer to as stacked magnetic resonator (SMR). By combining numerical and experimental methodologies, we prove that this passive solution allows an efficient decoupling of active elements of a phased-array coil. We demonstrate the ability of this technique to significantly reduce by more than 10 dB the coupling preserving the quality of images compared to ideally isolated linear resonators on a spherical salty agar gel phantom in a 7 T MRI scanner

Z-segmentation of a transmit array head coil improves RF ramp pulse design at 7T

International audienceIn Time-Of-Flight sequences, ramp pulses such as TONE's are frequently used to compensate for thru-slab blood flow saturation in cerebral MRA. At Ultra High Field, fast-kz spokes in parallel transmission allow to mitigate B1 + heterogeneities in the slab selection process. Here we extend their use for TONE pulses and show improvement of the flip angle ramp fidelity with a homemade z-segmented head array in comparison to a purely azimuthally-distributed commercial coil

Simultaneous multi-parametric mapping of total sodium concentration, T1, T2 and ADC at 7 T using a multi-contrast unbalanced SSFP

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Simultaneous multi-parametric and quantitative estimation of 23Na physical properties at 7 Tesla using QuICS

International audienceQuantifying physical properties of sodium could be of benefit to assess more specifically changes in cellular homeostasis accompanying neuroinflammatory or neurodegenerative diseases. This work aimed at adapting for ^\textrm23Na MRI at 7 Tesla the Quantitative Imaging using Configuration States (QuICS) method, primarily developped for ^\textrm1H MRI. We demonstrate the possibility to not only estimate accurately the T_\textrm1, T_\textrm2, FA, M_\textrm0 and ADC simultaneously for ^\textrm23Na at physiological concentration at UHF, but to acquire 3D maps for all of them