Investigation of the B1 field distribution and RF power deposition in a birdcage coil as functions of the number of coil legs at 4.7 T, 7.0 T, and 11.7 T

Seo, Jeung-Hoon; Han, Sang-Doc; Kim, Kyoung Nam

doi:10.3938/jkps.66.1822

Cited by 7 publications

(8 citation statements)

References 24 publications

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“…However, at higher field intensity (>= 7T), the BC coil has some limitations with field distribution uniformity, since the wavelength inside the human body is short (23). Seo et al (73) analyzed the |B 1 |-field distribution uniformity with regard to the number of legs of the BC coil for 4.7T, 7.0T, and 11.7T. The BC coils had 8, 16, 32, 64, and 128 legs.…”

Section: π Wmentioning

confidence: 99%

A Review on the RF Coil Designs and Trends for Ultra High Field Magnetic Resonance Imaging

Hernández

Kim

2020

Investig Magn Reson Imaging

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Radiofrequency (RF) coils are a vital part of magnetic resonance imaging (MRI). It is through RF coils that a magnetic flux (|B 1 |)-field is transmitted to the imaging object to excite protons, which, in turn, emit RF signals, which are then captured by the RF coils (1). The main function of the RF coils is to transmit (Tx) and receive (Rx) signals. When the imaging object is exposed to a strong magnetic (|B 0 |)-field of the MRI scanner, its spins are magnetized, aligning them with the |B 0 |-field. Consequently, a perpendicular magnetic field is excited using an RF Tx coil, and the RF magnetic pulse deviates the spins vector from the aligned direction of |B 0 |-field. The stronger the RF

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Section: π Wmentioning

confidence: 99%

A Review on the RF Coil Designs and Trends for Ultra High Field Magnetic Resonance Imaging

Hernández

Kim

2020

Investig Magn Reson Imaging

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“…A BC coil with N legs has different resonant modes [8,9]. In those modes, operating frequency can be predicted among other modes, such as ring modes [10], and is known to have more uniform |B + 1 | field distribution when the number of legs increases [11]. However, the BC coil underperforms when used in higher frequencies, because the magnetic field interacts with brain tissues that have different electromagnetic properties (conductivity and permittivity) [12].…”

Section: Introductionmentioning

confidence: 99%

Simulation Design of Incremental Leg Tapered Birdcage Coil for Head Imaging at 4.7T MRI

2021

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This study analyzed asymmetrical designs of birdcage (BC) coils, for which the conventional shape of the BC is modified in order to improve field intensity and uniformity in the brain region for magnetic resonance imaging (MRI) at 4.7T. Typically the BC coil has insufficient field uniformity when operating at higher frequencies such as 200 MHz, corresponding to the Larmor frequency at 4.7T, due to the interaction between the electrical properties of body tissue and the propagated magnetic field wavelength. We propose a new design of BC coil, which consists of different ring diameters and leg width. The performance of proposed designs was compared to that of a body-size BC coil. Using finite-difference time-domain simulations to obtain the |B1+| fields for a human model, we demonstrate that the proposed designs can achieve better field intensity and uniformity compared with other BC coil designs.

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“…and uniformly receives a freeinduction decay signal from the subject. 14 The BC coil also contains capacitors and inductors to form a resonator and is classified as a high-pass filter (HPF), low-pass filter (LPF), or band-pass filter depending on the positioning of the capacitors. 12 Geometrically, the BC coil can be optimized by controlling the number of rungs between the end rings.…”

Section: Introductionmentioning

confidence: 99%

“…12 Geometrically, the BC coil can be optimized by controlling the number of rungs between the end rings. The magnetic flux density of the jB 1 j field of a BC coil increases with the number of rungs, which is usually in the range of [8][9][10][11][12][13][14][15][16]. 13 Increasing the number of rungs can improve the jB 1 j-field sensitivity, but self-inductance coupling can result in jB 1 j-field interaction.…”

Section: Introductionmentioning

confidence: 99%

“…13 Increasing the number of rungs can improve the jB 1 j-field sensitivity, but self-inductance coupling can result in jB 1 j-field interaction. 14 The BC coil also contains capacitors and inductors to form a resonator and is classified as a high-pass filter (HPF), low-pass filter (LPF), or band-pass filter depending on the positioning of the capacitors. 15 In general, the diameter of a BC coil for an animal is much smaller than that for a human; therefore, the capacitor value is larger.…”

Section: Introductionmentioning

confidence: 99%

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A study on multiple array method of birdcage coils to improve the signal intensity and homogeneity in small‐animal whole‐body magnetic resonance imaging at 7 T

Heo

Kim

Han

et al. 2019

Int J Imaging Syst Tech

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Investigation of the B1 field distribution and RF power deposition in a birdcage coil as functions of the number of coil legs at 4.7 T, 7.0 T, and 11.7 T

Cited by 7 publications

References 24 publications

A Review on the RF Coil Designs and Trends for Ultra High Field Magnetic Resonance Imaging

A Review on the RF Coil Designs and Trends for Ultra High Field Magnetic Resonance Imaging

Simulation Design of Incremental Leg Tapered Birdcage Coil for Head Imaging at 4.7T MRI

A study on multiple array method of birdcage coils to improve the signal intensity and homogeneity in small‐animal whole‐body magnetic resonance imaging at 7 T

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