Design and Modeling of a Radiofrequency Coil Derived from a Helmholtz Structure
This paper focuses on radiofrequency (RF) coils that can produce a high electromagnetic field homogeneity to be used for magnetic resonance imaging (MRI) applications. The proposed structure is composed of four wire loops symmetrically located on an ellipsoidal surface. The main objective of this work is to improve field homogeneity compared to a standard Helmholtz coil. Numerical simulation was carried out to assess the RF electromagnetic field behavior of the proposed coil. Different electrical modeling and simulations were investigated, particularly the study of the whole modeling of the proposed structure taking into account all the couplings between the loops. The proposed coil was evaluated and compared with the standard Helmholtz coil. Simulation and experimental results confirmed the good performance of the developed coil in terms of electromagnetic field homogeneity, efficiency, sensitivity, and quality factor.
Keywords:radiofrequency coils, modeling, simulation, design, electromagnetic field homogeneity, impedance measurements, MRI
F. Remeo, D. I. Hoult, “Magnet field profiling: Analysis and correcting coil design”, Magnetic Resonance in Medicine, Vol. 1, No. 1, pp. 44- 65, 1984 DOI: https://doi.org/10.1002/mrm.1910010107
C. E. Hayes, W. A. Edelstein, J. F. Schenck, O. M. Mueller, M. Eash, “An efficient, highly homogeneous radiofrequency coil for whole-body NMR imaging at 1.5 T”, Journal of Magnetic Resonance, Vol. 63, No. 3, pp. 622-628, 1985 DOI: https://doi.org/10.1016/0022-2364(85)90257-4
J. T. Vaughan, H. P. Hetherington, J. O. Out, J. W. Pan, G. M. Pohost, “High frequency volume coils for clinical NMR imaging and spectroscopy”, Magnetic Resonance in Medicine, Vol. 32, No. 2, pp. 206-218, 1994 DOI: https://doi.org/10.1002/mrm.1910320209
K. Asher, N. K. Bangerter, R. D. Watkins, G. E. Gold, “Radiofrequency Coils for Musculoskeletal MRI”, Topics in Magnetic Resonance Imaging, Vol. 21, No. 5, pp. 315-323, 2010 DOI: https://doi.org/10.1097/RMR.0b013e31823cd184
Q. X. Yang, S. Li, M. B. Smith, “A Method for Evaluating the Magnetic Field Homogeneity of a Radiofrequency Coil by Its Field Histogram”, Journal of Magnetic Resonance, Series A, Vol. 108, No. 1, pp. 1-8, 1994 DOI: https://doi.org/10.1006/jmra.1994.1081
S. Li, Q. X. Yang, M. B. Smith, “RF coil optimization: Evaluation of B1 field homogeneity using field histograms and finite element calculations”, Magnetic Resonance Imaging, Vol. 12, No. 7, pp. 1079-1087, 1994 DOI: https://doi.org/10.1016/0730-725X(94)91240-W
B. Gruber, M. Froeling, T. Leiner, D. W. J. Klomp, “RF coils: A practical guide for nonphysicists”, Journal of Magnetic Resonance Imaging, Vol. 48, No. 3, pp. 590-604, 2018 DOI: https://doi.org/10.1002/jmri.26187
J. Mispelter, M. Lupu, A. N. M. R. Briguet, NMR Probeheads for Biophysical and Biomedical Experiments: Theoretical Principles & Practical Guidelines, Imperial College Press, 2006 DOI: https://doi.org/10.1142/p438
B. J. Dardzin, S. S. Li, C. M. Collins, G. D.Williams, M. B. Smith, “A Birdcage Coil Tuned by RF Shielding for Application at 9.4 T”, Journal of Magnetic Resonance, Vol. 131, No. 1, pp. 32-38, 1998 DOI: https://doi.org/10.1006/jmre.1997.1334
S. M. A. Ghaly, S. S. Al-Sowayan, “A high B1 field homogeneity generation using free element elliptical four-coil system”, American Journal of Applied Sciences, Vol. 11, No. 4, pp. 534-540, 2014 DOI: https://doi.org/10.3844/ajassp.2014.534.540
S. M. A. Ghaly, K. A. Al-Snaie, S. S. Al-Sowayan, “Design and Testing of Radiofrequency Spherical Four Coils”, Modern Applied Science, Vol. 10, No. 5, pp. 186-193, 2016 DOI: https://doi.org/10.5539/mas.v10n5p186
S. M. A. Ghaly, K. A. Al-Snaie, O. K. Mohammad, “Spherical and Improved Helmholtz Coil with High B1 Homogeneity for Magnetic Resonance Imaging”, American Journal of Applied Sciences, Vol. 13, No. 12, pp. 1413-1418, 2016 DOI: https://doi.org/10.3844/ajassp.2016.1413.1418
J. Wang, S. She, S. Zhang, “An improved Helmholtz coil and analysis of its magnetic field homogeneity”, Review of Scientific Instruments, Vol. 73, No. 5, pp. 2175-2179, 2002 DOI: https://doi.org/10.1063/1.1471352
M. Decorps, P. Blondet, H. Reutenauer, J. P. Albrand, C. Remy, “An inductively coupled, series tuned NMR probe”, Journal of Magnetic Resonance, Vol. 65, No. 1, pp. 100-109, 1995 DOI: https://doi.org/10.1016/0022-2364(85)90378-6
J. Murphy-Boesch, A. P. Koretsky, “An in vivo NMR probe circuit for improved sensitivity”, Journal of Magnetic Resonance, Vol. 54, No. 3, pp. 526-532, 2003 DOI: https://doi.org/10.1016/0022-2364(83)90333-5
R. F. Lee, R. O. Giaquinto, C. J. Hardy, “Coupling and Decoupling Theory and Its Application to the MRI Phased Array”, Magnetic Resonance in Medicine, Vol. 48, pp. 203-213, 2002 DOI: https://doi.org/10.1002/mrm.10186
C. M. Collins, Z. Wang, “Calculation of Radiofrequency Electromagnetic Fields and Their Effects in MRI of Human Subjects”, Magnetic Resonance in Medicine, Vol. 65, No. 5, pp. 1470-1482, 2011 DOI: https://doi.org/10.1002/mrm.22845
Y. E. Esin, F. N. Alpaslan, “MRI image enhancement using Biot–Savart law at 3 tesla”, Turkish Journal of Electrical Engineering & Computer Sciences, Vol. 25, pp. 3381-3396, 2017 DOI: https://doi.org/10.3906/elk-1604-348
D. M. Ginsberg, M. J. Melchner, “Optimum Geometry of saddle shaped coils for generating a uniform magnetic field”, Review of Scientific Instruments, Vol. 41, No. 1, pp. 122-123, 2010 DOI: https://doi.org/10.1063/1.1684235
H. Fujita, T. Zheng, X. Yang, M. J. Finnerty, S. Handa, “RF Surface Receive Array Coils: The Art of an LC Circuit”, Journal of Magnetic Resonance Imaging, Vol. 38, No. 1, pp. 12-25, 2013 DOI: https://doi.org/10.1002/jmri.24159
How to Cite
MetricsAbstract Views: 424
PDF Downloads: 201
Authors who publish with this journal agree to the following terms:
- Authors retain the copyright and grant the journal the right of first publication with the work simultaneously licensed under a Creative Commons Attribution License that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
- Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
- Authors are permitted and encouraged to post their work online (e.g., in institutional repositories or on their website) after its publication in ETASR with an acknowledgement of its initial publication in this journal.