Magnetic resonance butterfly coils: Design and application for hyperpolarized 13C studies

Giovannetti, Giulio; Frijia, Francesca; Attanasio, Simona; Menichetti, Luca; Hartwig, Valentina; Vanello, Nicola; Ardenkjær‐Larsen, Jan Henrik; Marchi, Daniele De; Positano, Vincenzo; Schulte, Rolf F.; Landini, Luigi; Lombardi, Massimo; Santarelli, Maria Filomena

doi:10.1016/j.measurement.2013.06.031

Cited by 11 publications

(7 citation statements)

References 20 publications

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“…Magnetic field estimation method was experimentally verified by workbench measurement on birdcage coil 20 and by extracting magnetic field profiles in B 1 maps acquired with a solenoid 5 and an elliptical surface coil. 21 T A B L E 4 Estimated magnetic field per unit current (CL, circular loop with b radius; SL, square loop with S side) Analytical calculation employed for inductance estimation was experimentally verified by workbench measurement on birdcage coil 20 and on 13 C butterfly coils, 22 showing resonant frequency deviations lower than 2.2% and 5.2% for, respectively, birdcage and butterfly, compatible with the capacitor tolerances used in the coils construction. Moreover, mutual inductance calculations performed on phased-array of circular and rectangular loops confirmed literature empirical data in terms of mutual interaction patterns.…”

Section: Discussionmentioning

confidence: 82%

“…Analytical calculation employed for inductance estimation was experimentally verified by workbench measurement on birdcage coil and on 13 C butterfly coils, showing resonant frequency deviations lower than 2.2% and 5.2% for, respectively, birdcage and butterfly, compatible with the capacitor tolerances used in the coils construction. Moreover, mutual inductance calculations performed on phased‐array of circular and rectangular loops confirmed literature empirical data in terms of mutual interaction patterns …”

Section: Discussionmentioning

confidence: 89%

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Sensitivity estimation in circular and square loops

Giovannetti

2018

Concepts Magnetic Resonance

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Circular and square loops are the simplest design employed as radiofrequency coils for magnetic resonance applications. Being usually much smaller than the volume coils, these loop coils have higher signal‐to‐noise ratio (SNR) because they receive noises only from nearby regions. However, they have a relatively poor field homogeneity and, thus, are mainly used as receive coils. In this work, author describes a coil sensitivity estimation method based on a simulator which permits the characterization of loop coils performance, in terms of magnetic field patterns and coil losses, where this last term including conductor, sample, capacitor, radiative and soldering losses. The evaluation of coil sensitivity for circular and square loops was performed at different tuning frequencies usually used in clinical scanner (21, 64, and 128 MHz) and at different distances respect to the coil plane. Simulation data were acquired for circular loop radius between 0.5 and 4 cm and for square loop side sizes between 1 and 8 cm, with the scope of evaluating the loop sizes which maximize the sensitivity in dependence of the penetration depth in the sample region and therefore to design optimized coils for maximizing SNR in MR applications.

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Section: Discussionmentioning

confidence: 82%

Section: Discussionmentioning

confidence: 89%

Sensitivity estimation in circular and square loops

Giovannetti

2018

Concepts Magnetic Resonance

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“…The quadrature surface coil, consisting of a combination of the butterfly and the circular coil, was previously designed and tested as TX/RX configuration. The obtained SNR was higher as compared with the SNRs provided by the single coils in a wide range of the penetration depth into the phantom (Figure 10), while the MR acquisition of metabolic maps with hyperpolarized [1-13 C]pyruvate injected in a pig showed that the configuration was able to effectively image the hyperpolarized [1-13 C]pyruvate distribution, Successively, the same quadrature surface coil was used in RX mode in combination with a birdcage coil as a transmitter [66]. For this purpose, a passive decoupling circuit was added to both surface coils, as described in a previous paragraph.…”

Section: Quadrature Surface Coil In Tx/rx and Rx Onlymentioning

confidence: 99%

“…The theoretical SNR trends of dependence on the depth profile along the sample region (from 2 to 12 cm) are shown in Figure 10 for all coil configurations. was able to effectively image the hyperpolarized [1-13 C]pyruvate distribution, Successively, the same quadrature surface coil was used in RX mode in combination with a birdcage coil as a transmitter [66]. For this purpose, a passive decoupling circuit was added to both surface coils, as described in a previous paragraph.…”

Section: Theoretical Comparison Between 13 C Coil Snr Plotsmentioning

confidence: 99%

Radio Frequency Coils for Hyperpolarized 13C Magnetic Resonance Experiments with a 3T MR Clinical Scanner: Experience from a Cardiovascular Lab

et al. 2021

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Hyperpolarized 13C magnetic resonance (MR) is a promising technique for the noninvasive assessment of the regional cardiac metabolism since it permits heart physiology studies in pig and mouse models. The main objective of the present study is to resume the work carried out at our electromagnetic laboratory in the field of radio frequency (RF) coil design, building, and testing. In this paper, first, we review the principles of RF coils, coil performance parameters, and estimation methods by using simulations, workbench, and MR imaging experiments. Then, we describe the simulation, design, and testing of different 13C coil configurations and acquisition settings for hyperpolarized studies on pig and mouse heart with a clinical 3T MRI scanner. The coil simulation is performed by developing a signal-to-noise ratio (SNR) model in terms of coil resistance, sample-induced resistance, and magnetic field pattern. Coil resistance was calculated from Ohm’s law and sample-induced resistances were estimated with a finite-difference time-domain (FDTD) algorithm. In contrast, the magnetic field per unit current was calculated by magnetostatic theory and a FDTD algorithm. The information could be of interest to graduate students and researchers working on the design and development of an MR coil to be used in 13C studies.

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“…A comparison between a commercial 13 C quadrature birdcage coil and a homebuilt 13 C circular coil, both designed for hyperpolarized studies of the porcine heart with a clinical 3T scanner, was introduced in [8], and was carried out in terms of sensitivity regions and SNR. Furthermore two RX butterfly coils were presented with different geometries for 13 C hyperpolarized studies of pigs [9]; experimental SNR profiles acquired in a phantom highlight the advantage of this configuration over a volume birdcage coil in a wide range of coil-to-voxel distances.…”

Section: Introductionmentioning

confidence: 99%

16-Channel Surface Coil for 13C-Hyperpolarized Spectroscopic Imaging of Cardiac Metabolism in Pig Heart

et al. 2016

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Abstract\ud Purpose: Magnetic resonance spectroscopy of hyperpolarized 13C pyruvate and its\ud metabolites in large animal models is a powerful tool for assessing cardiac metabolism in\ud patho-physiological conditions. In 13C studies the Signal-to-Noise Ratio (SNR) could be\ud crucial, to overcome intrinsic data quality limitation due to the low molar concentration of\ud certain metabolites as well as the low flux of conversion. On the other hand, since 13C-MRS\ud is essentially a semi-quantitative technique, the SNR among the spectra acquired in different\ud myocardial segments should be homogeneous. MR coil design plays an important role in\ud achieving both targets.\ud Materials and Methods: In this study, a receive 16-channels surface coil was designed for\ud 13C hyperpolarized studies of pig heart with a clinical 3T scanner. The coil performances\ud were characterized by phantom experiments, and compared with a birdcage coil used in\ud transmit/receive mode. Segmental signal distribution in the left ventricle (LV) was assessed\ud by experiments on six healthy mini pigs.\ud Results: The proposed coil showed a significant increase in SNR in the LV wall close to the\ud coil surface with respect to the birdcage but also a significant segmental inhomogeneity.\ud Conclusion: The use of the 16-channel coil would be recommended in studies of septal\ud and anterior LV walls

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Magnetic resonance butterfly coils: Design and application for hyperpolarized 13C studies

Cited by 11 publications

References 20 publications

Sensitivity estimation in circular and square loops

Sensitivity estimation in circular and square loops

Radio Frequency Coils for Hyperpolarized 13C Magnetic Resonance Experiments with a 3T MR Clinical Scanner: Experience from a Cardiovascular Lab

16-Channel Surface Coil for 13C-Hyperpolarized Spectroscopic Imaging of Cardiac Metabolism in Pig Heart

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