Multi‐channel helical‐antenna inner‐volume <scp>RF</scp> coils for ultra‐high field <scp>MR</scp> scanners

Athalye, Pranav S.; Ilić, Milan M.; Moortele, Pierre-François Van de; Kiruluta, Andrew J.M.; Notaroš, Branislav M.

doi:10.1002/cmr.b.21405

Cited by 7 publications

(1 citation statement)

References 47 publications

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“…The basic idea of the novel method for RF excitation at high and ultrahigh fields by means of quadrifilar helical antennas as RF body coils and initial results at both 3 T and 7 T are preliminary presented in a summary form in Refs . A subject‐loaded monofilar axial‐mode helical antenna as an RF exciter for 7‐T MRI systems is preliminary presented in a summary form in Ref.…”

Section: Introductionmentioning

confidence: 99%

Subject‐loaded quadrifilar helical‐antenna RF coil with high B₁⁺ field uniformity and large FOV for 3‐T MRI

Athalye

Sekeljic

Ilić

et al. 2016

Concepts Magn Reson

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A novel method for excitation of RF B1 field in high‐field (3‐T) magnetic resonance imaging (MRI) systems using a subject‐loaded quadrifilar helical antenna as an RF coil is proposed, evaluated, and demonstrated. Design, analysis, characterization, and evaluation of the novel coil when situated in a 3‐T MRI bore and loaded with different phantoms are performed and cross‐validated by extensive numerical simulations using multiple computational electromagnetics techniques. The results for the quadrifilar helical‐antenna RF body coil show (a) strong field penetration in the entire phantoms; (b) excellent right‐hand circular polarization (RCP); (c) high spatial uniformity of RCP RF magnetic field, B1+, throughout the phantoms; (d) large field of view (FOV); (e) good transmit efficiency; and (f) low local specific absorption rate (SAR). The examples show that the new RF coil provides substantially better B1+‐field uniformity and much larger FOV than any of the previously reported numerical and experimental results for the existing RF coil designs at 3 T in literature that enable comparison. In addition, helical RF body coils of different lengths can, for instance, easily provide an excellent RCP and highly uniform B1+‐field within the MRI maximum FOV length of 50 cm, and even 100 cm. The proposed MRI RF coil yields a remarkable improvement in the field uniformity in the longitudinal direction, for various phantoms, with comparable efficiency and SAR levels.

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Section: Introductionmentioning

confidence: 99%

Subject‐loaded quadrifilar helical‐antenna RF coil with high B₁⁺ field uniformity and large FOV for 3‐T MRI

Athalye

Sekeljic

Ilić

et al. 2016

Concepts Magn Reson

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Metamaterial Liner for MRI Excitation—Part 2: Design and Performance at 4.7T

2022

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The theoretical foundations of a metamaterial (MM) liner for the MRI bore that facilitates the propagation of reduced-cutoff cylindrical waveguide modes are presented in the Part 1 companion paper to this work. Here, in Part 2, the practical design and modelling of the novel MM liner is applied to a body MRI radio-frequency (RF) transmitter for 4.7T. An equivalent network mesh model is developed to reduce the distributed structure of the MM to one that uses lumped discrete tuning elements. The close match between full-wave simulation and the network model is demonstrated by comparison of the longitudinal propagation dispersion curves and input impedance. The application of the methods developed for analysis of the MM liner behavior are demonstrated in the design of a practical MM liner as an effective MRI RF transmitter. The liner's simulated performance was evaluated using three key metrics of MR radio-frequency (RF) coil performance: transmit efficiency, the variation of the transmit field (a measure of homogeneity), and the 10g averaged local specific absorption rate (SAR). These metrics are compared to those of the commonly used birdcage (BC) coil. The main advantage of the MM liner is the 29.6% reduction in maximum SAR normalized to transmit field relative to the BC coil, with comparable transmit efficiency and homogeneity. Thus, the liner can potentially replace the BC coil as an RF transmitter and provide an enhanced safety margin, or allow the use of faster, more SAR-aggressive imaging sequences.

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Design of Rotated Surface Coil Array for Multiple-Subject Imaging at 400 MHz

et al. 2022

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Multi‐channel helical‐antenna inner‐volume RF coils for ultra‐high field MR scanners

Cited by 7 publications

References 47 publications

Subject‐loaded quadrifilar helical‐antenna RF coil with high B₁⁺ field uniformity and large FOV for 3‐T MRI

Subject‐loaded quadrifilar helical‐antenna RF coil with high B₁⁺ field uniformity and large FOV for 3‐T MRI

Metamaterial Liner for MRI Excitation—Part 2: Design and Performance at 4.7T

Design of Rotated Surface Coil Array for Multiple-Subject Imaging at 400 MHz

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Multi‐channel helical‐antenna inner‐volume RF coils for ultra‐high field MR scanners

Cited by 7 publications

References 47 publications

Subject‐loaded quadrifilar helical‐antenna RF coil with high B1+ field uniformity and large FOV for 3‐T MRI

Subject‐loaded quadrifilar helical‐antenna RF coil with high B1+ field uniformity and large FOV for 3‐T MRI

Metamaterial Liner for MRI Excitation—Part 2: Design and Performance at 4.7T

Design of Rotated Surface Coil Array for Multiple-Subject Imaging at 400 MHz

Contact Info

Product

Resources

About

Subject‐loaded quadrifilar helical‐antenna RF coil with high B₁⁺ field uniformity and large FOV for 3‐T MRI

Subject‐loaded quadrifilar helical‐antenna RF coil with high B₁⁺ field uniformity and large FOV for 3‐T MRI