Abstract
Object
We have developed a single-channel, box-shaped, monopole-type antenna which, if used in two different configurations, excites complementary B1+ field distributions in the traveling-wave setup.
Materials and methods
A new monopole-type, single-channel antenna for RF excitation in 9.4 T magnetic resonance imaging is proposed. The antenna is entirely made of copper without lumped elements. Two complementary B1+ field distributions of two different antenna configurations were measured and combined as a root sum of squares. B1+ field inhomogeneity of the combined maps was calculated and compared with published results.
Results
By combining B1+ field distributions generated by two antenna configurations, a “no voids” pattern was achieved for the entire upper brain. B1+ inhomogeneity of approximately 20 % was achieved for sagittal and transverse slices; it was <24 % for coronal slices. The results were comparable with those from CP, with “no voids” in slice B1+ inhomogeneity of multichannel loop arrays. The efficiency of the proposed antenna was lower than that of a multichannel array but comparable with that of a patch antenna.
Conclusion
The proposed single-channel antenna is a promising candidate for traveling-wave brain imaging. It can be combined with the time-interleaved acquisition of modes (TIAMO) concept if reconfigurability is obtained with a single-antenna element.
Similar content being viewed by others
References
Brunner DO, De Zanche N, Frohlich J, Paska J, Pruessmann KP (2009) Travelling wave nuclear magnetic resonance. Nature 475:994–998
Andreychenko AE (2013) Radio frequency solutions in clinical high field magnetic resonance. PhD thesis, Utrecht University, The Netherlands, ISBN: 978-94-6108-486-6
Brunner DO, De Zanche N, Froehlich J, Paska J, Pruessmann KP (2009) Travelling-wave MRI: initial results of in vivo head imaging at 7T. In: Proceedings of the 17th annual meeting, international society for magnetic resonance in medicine, Honolulu, Hawaii, p 500
Hoffmann J, Shajan G, Budde J, Scheffler K, Pohmann R (2013) Human brain imaging at 9.4 T using a tunable patch antenna for transmission. Magn Reson Med 69:1494–1500
Webb AG, Collins CM, Versluis MJ, Kan HE, Smith NB (2010) MRI and localized proton spectroscopy in human leg muscle at 7 tesla using longitudinal traveling waves. Magn Reson Med 63:297–302
Geschewski FH, Brenner D, Felder J, Shah NJ (2013) Optimum coupling and multimode excitation of traveling-waves in a whole body 9.4 T scanner. Magn Reson Med 69:1805–1812
Brunner DO, Paska J, Froechlich J, Pruessmann K (2011) Traveling-wave RF shimming and parallel MRI. Magn Reson Med 66:290–300
Van der Berg CA, Kroeze H, van de Bank BL, van den Bergen B, Luijten PR, Lagendijk JJ, Klomp DW (2009) Optimizing traveling wave RF excitation for in vivo use. In: Proceedings of the 17th annual meeting, international society for magnetic resonance in medicine, Honolulu, Hawaii, p 2994
Andreychenko A, Kroeze H, Klomp DW, Lagendijk JJ, Luijten P, van den Berg CA (2010) A novel matching strategy to increase power efficiency of the traveling wave MRI imaging. In: Proceedings of the 18th annual meeting, international society for magnetic resonance in medicine, Stockholm, Sweden, p 3790
Zivkovic I, Scheffler K (2013) A new antenna concept for RF excitation at 9.4 T. In: Proceedings of 30th annual scientific meeting, European society for magnetic resonance in medicine and biology, Toulouse, France, Magn Reson Mater Phy 26:189–190
Orzada S, Maderwald S, Poser BA, Bitz AK, Quick HH, Ladd M (2010) RF excitation using time interleaved acquisition of modes (TIAMO) to address B1 inhomogeneity in high-field MRI. Magn Reson Med 64:327–333
Orzada S, Mardewald S, Poser BA, Johst S, Kannengiesser, Ladd ME, Bitz BA (2012) Time-interleaved acquision of modes: an analysis of SAR and image contrast implications. Magn Reson Med 67:1033–1041
Zivkovic I, Scheffler K (2013) A new innovative antenna concept for both narrow band and UWB applications. PIER 139:121–131
Gonzalez JM, Romeu J (2002) Measurement of radiation efficiency and quality factor of fractal antennas: the wheeler cap method. IST FRACTALCOMS, UPC, D11 T4.3 final task report
Niamien C, Collardey S, Sharaiha A, Mahdjoubi K (2011) Compact expressions for the efficiency and bandwidth of patch antennas over lossy magneto-dielectric materials. IEEE Antennas Wirel Propag Lett 10:63–66
Hoffmann J, Shajan G, Scheffler K, Pohmann R (2013) Combination of multimode traveling-wave excitation and TIAMO for human brain imaging at 9.4 T. In: Proceedings of 30th annual scientific meeting, European society for magnetic resonance in medicine and biology, Toulouse, France, Magn Reson Mater Phy 26:192
Zhang B, Sodickson DK, Lattanzi R, Duan Q, Stoeckel B, Wiggins GC (2012) Whole body traveling wave magnetic resonance imaging at high field strength: homogeneity, efficiency, and energy deposition as compared with traditional excitation mechanisms. Magn Reson Med 67:1183–1193
Hoffmann J, Shajan G, Scheffler K, Pohmann R (2013) Numerical and experimental evaluation of RF shimming in the human brain at 9.4 T using a dual-row transmit array. Magn Reson Mater Phy. (Epub ahead). doi:10.1007/s10334-013-0419-y
Zivkovic I, Scheffler K (2014) Metamaterial Cell for B1+ Field Manipulation at 9.4 T MRI. In: Proceedings of joint annual meeting, international society for magnetic resonance in medicine and European society for magnetic resonance in medicine and biology, Milano, Italy, p 4834
Conflict of interest
The authors declare that they have no conflict of interest.
Ethical standards
The manuscript does not contain clinical studies or patient data.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Zivkovic, I., Scheffler, K. Single-channel, box-shaped, monopole-type antenna for B1+ field manipulation in conjunction with the traveling-wave concept in 9.4 T MRI. Magn Reson Mater Phy 28, 357–362 (2015). https://doi.org/10.1007/s10334-014-0473-0
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10334-014-0473-0