Dataset Information

Integrated parallel reception, excitation, and shimming (iPRES) with multiple shim loops per radio-frequency coil element for improved B0 shimming.

ABSTRACT: Integrated parallel reception, excitation, and shimming (iPRES) coil arrays allow radio-frequency currents and direct currents to flow in the same coils, which enables excitation/reception and localized B0 shimming with a single coil array. The purpose of this work was to improve their shimming performance by adding the capability to shim higher-order local B0 inhomogeneities that are smaller than the radio-frequency coil elements.A novel design was proposed in which each radio-frequency/shim coil element is divided into multiple direct current loops, each using an independent direct current current, to increase the number of magnetic fields available for shimming while maintaining the signal-to-noise ratio of the coil. This new design is termed iPRES(N), where N represents the number of direct current loops per radio-frequency coil element. Proof-of-concept phantom and human experiments were performed with an 8-channel body coil array to demonstrate its advantages over the original iPRES(1) design.The average B0 homogeneity in various organs before shimming and after shimming with the iPRES(1) or iPRES(3) coil arrays was 0.24, 0.11, and 0.05 ppm, respectively. iPRES(3) thus reduced the B0 inhomogeneity by 53% and further reduced distortions in echo-planar images of the abdomen when compared with iPRES(1).iPRES(N) can correct for localized B0 inhomogeneities more effectively than iPRES(1) with no signal-to-noise ratio loss, resulting in a significant improvement in image quality. Magn Reson Med 77:2077-2086, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

SUBMITTER: Darnell D

PROVIDER: S-EPMC5107366 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Integrated parallel reception, excitation, and shimming (iPRES) with multiple shim loops per radio-frequency coil element for improved B<sub>0</sub> shimming.

Darnell Dean D Truong Trong-Kha TK Song Allen W AW

Magnetic resonance in medicine 20160513 5

<h4>Purpose</h4>Integrated parallel reception, excitation, and shimming (iPRES) coil arrays allow radio-frequency currents and direct currents to flow in the same coils, which enables excitation/reception and localized B<sub>0</sub> shimming with a single coil array. The purpose of this work was to improve their shimming performance by adding the capability to shim higher-order local B<sub>0</sub> inhomogeneities that are smaller than the radio-frequency coil elements.<h4>Methods</h4>A novel des ...[more]

PMID: 27174387

Similar Datasets

Project description:The in vivo rat model is a workhorse in neuroscience research, preclinical studies and drug development. A repertoire of MR tools has been developed for its investigation; however, high levels of B0 magnetic field homogeneity are required for meaningful results. The homogenization of magnetic fields in the rat brain, i.e. shimming, is a difficult task because of a multitude of complex, susceptibility-induced field distortions. Conventional shimming with spherical harmonic (SH) functions is capable of compensating for shallow field distortions in limited areas, e.g. in the cortex, but performs poorly in difficult-to-shim subcortical structures or for the entire brain. Based on the recently introduced multi-coil approach for magnetic field modeling, the DYNAmic Multi-coIl TEchnique (DYNAMITE) is introduced for magnetic field shimming of the in vivo rat brain and its benefits for gradient-echo echo-planar imaging (EPI) are demonstrated. An integrated multi-coil/radiofrequency (MC/RF) system comprising 48 individual localized DC coils for B0 shimming and a surface transceive RF coil has been developed that allows MR investigations of the anesthetized rat brain in vivo. DYNAMITE shimming with this MC/RF set-up is shown to reduce the B0 standard deviation to a third of that achieved with current shim technology employing static first- through third-order SH shapes. The EPI signal over the rat brain increased by 31%, and a 24% gain in usable EPI voxels could be realized. DYNAMITE shimming is expected to critically benefit a wide range of preclinical and neuroscientific MR research. Improved magnetic field homogeneity, together with the achievable large brain coverage of this method, will be crucial when signal pathways, cortical circuitry or the brain's default network are studied. Together with the efficiency gains of MC-based shimming compared with SH approaches demonstrated recently, DYNAMITE shimming has the potential to replace conventional SH shim systems in small-bore animal scanners.

Dataset Information

Integrated parallel reception, excitation, and shimming (iPRES) with multiple shim loops per radio-frequency coil element for improved B0 shimming.

Publications

Integrated parallel reception, excitation, and shimming (iPRES) with multiple shim loops per radio-frequency coil element for improved B<sub>0</sub> shimming.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure