Skip to main content
SpringerLink
Log in

Numerical and experimental evaluation of RF shimming in the human brain at 9.4 T using a dual-row transmit array

  • Research Article
  • Published:
Magnetic Resonance Materials in Physics, Biology and Medicine Aims and scope Submit manuscript

Abstract

Objective

To provide a numerical and experimental investigation of the static RF shimming capabilities in the human brain at 9.4 T using a dual-row transmit array.

Materials and methods

A detailed numerical model of an existing 16-channel, inductively decoupled dual-row array was constructed using time-domain software together with circuit co-simulation. Experiments were conducted on a 9.4 T scanner. Investigation of RF shimming focused on B1 + homogeneity, efficiency and local specific absorption rate (SAR) when applied to large brain volumes and on a slice-by-slice basis.

Results

Numerical results were consistent with experiments regarding component values, S-parameters and B1 + pattern, though the B1 + field was about 25 % weaker in measurements than simulations. Global shim settings were able to prevent B1 + field voids across the entire brain but the capability to simultaneously reduce inhomogeneities was limited. On a slice-by-slice basis, B1 + standard deviations of below 10 % without field dropouts could be achieved in axial, sagittal and coronal orientations across the brain, even with phase-only shimming, but decreased B1 + efficiency and SAR limitations must be considered.

Conclusion

Dual-row transmit arrays facilitate flexible 3D RF management across the entire brain at 9.4 T in order to trade off B1 + homogeneity against power-efficiency and local SAR.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8

Similar content being viewed by others

References

  1. Van de Moortele PF, Akgun C, Adriany G, Moeller S, Ritter J, Collins CM, Smith MB, Vaughan JT, Ugurbil K (2005) B(1) destructive interferences and spatial phase patterns at 7 T with a head transceiver array coil. Magn Reson Med 54(6):1503–1518

    Article  PubMed  Google Scholar 

  2. Yang QX, Wang J, Zhang X, Collins CM, Smith MB, Liu H, Zhu XH, Vaughan JT, Ugurbil K, Chen W (2002) Analysis of wave behavior in lossy dielectric samples at high field. Magn Reson Med 47(5):982–989

    Article  PubMed  Google Scholar 

  3. Vaughan JT, Garwood M, Collins CM, Liu W, DelaBarre L, Adriany G, Andersen P, Merkle H, Goebel R, Smith MB, Ugurbil K (2001) 7T vs. 4T: RF power, homogeneity, and signal-to-noise comparison in head images. Magn Reson Med 46(1):24–30

    Article  PubMed  CAS  Google Scholar 

  4. Robitaille PM, Berliner LJ (2006) Ultra high field magnetic resonance imaging, vol 26. Biological Magnetic Resonance, Springer, New York

    Google Scholar 

  5. Vaughan T, DelaBarre L, Snyder C, Tian J, Akgun C, Shrivastava D, Liu W, Olson C, Adriany G, Strupp J, Andersen P, Gopinath A, van de Moortele PF, Garwood M, Ugurbil K (2006) 9.4T human MRI: preliminary results. Magn Reson Med 56(6):1274–1282

    Article  PubMed  Google Scholar 

  6. 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(5):1494–1500

    Article  PubMed  Google Scholar 

  7. Shajan G, Hoffmann J, Budde J, Adriany G, Ugurbil K, Pohmann R (2011) Design and evaluation of an RF front-end for 9.4 T human MRI. Magn Reson Med 66(2):596–604

    Article  PubMed  CAS  Google Scholar 

  8. Avdievich NI (2011) Transceiver-phased arrays for human brain studies at 7 T. Appl Magn Reson 41(2–4):483–506

    Article  PubMed  PubMed Central  Google Scholar 

  9. Ibrahim TS (2006) Ultrahigh-field MRI whole-slice and localized RF field excitations using the same RF transmit array. IEEE Trans Med Imaging 25(10):1341–1347

    Article  PubMed  Google Scholar 

  10. Mao W, Smith MB, Collins CM (2006) Exploring the limits of RF shimming for high-field MRI of the human head. Magn Reson Med 56(4):918–922

    Article  PubMed  PubMed Central  Google Scholar 

  11. Katscher U, Bornert P, Leussler C, van den Brink JS (2003) Transmit SENSE. Magn Reson Med 49(1):144–150

    Article  PubMed  Google Scholar 

  12. Setsompop K, Alagappan V, Gagoski B, Witzel T, Polimeni J, Potthast A, Hebrank F, Fontius U, Schmitt F, Wald LL, Adalsteinsson E (2008) Slice-selective RF pulses for in vivo B1+ inhomogeneity mitigation at 7 T using parallel RF excitation with a 16-element coil. Magn Reson Med 60(6):1422–1432

    Article  PubMed  PubMed Central  Google Scholar 

  13. van den Bergen B, van den Berg CA, Klomp DW, Lagendijk JJ (2009) SAR and power implications of different RF shimming strategies in the pelvis for 7T MRI. J Magn Reson Imaging 30(1):194–202

    Article  PubMed  Google Scholar 

  14. Homann H, Graesslin I, Eggers H, Nehrke K, Vernickel P, Katscher U, Dossel O, Bornert P (2012) Local SAR management by RF shimming: a simulation study with multiple human body models. Magn Reson Mater Phy 25(3):193–204

    Article  Google Scholar 

  15. de Greef M, Ipek O, Raaijmakers AJ, Crezee J, van den Berg CA (2013) Specific absorption rate intersubject variability in 7T parallel transmit MRI of the head. Magn Reson Med 69(5):1476–1485

    Article  PubMed  Google Scholar 

  16. Metzger GJ, Auerbach EJ, Akgun C, Simonson J, Bi X, Ugurbil K, van de Moortele PF (2013) Dynamically applied B1+ shimming solutions for non-contrast enhanced renal angiography at 7.0 T. Magn Reson Med 69(1):114–126

    Article  PubMed  PubMed Central  Google Scholar 

  17. Adriany G, Gozubuyuk A, Auerbach EJ, van de Moortele PF, Andersen P, Vaughan JT, Ugurbil K (2007) A 32 channel Transmit/Receive transmission line head array for 3D RF Shimming. In: proceedings of the 15th scientific meeting, International Society for Magnetic Resonance in Medicine, Berlin, p 166

  18. Gilbert KM, Curtis AT, Gati JS, Klassen LM, Menon RS (2011) A radiofrequency coil to facilitate B1 shimming and parallel imaging acceleration in three dimensions at 7 T. NMR Biomed 24(7):815–823

    Article  PubMed  Google Scholar 

  19. Shajan G, Kozlov M, Hoffmann J, Turner R, Scheffler K, Pohmann R (2013) A 16-channel dual-row transmit array in combination with a 31-element receive array for human brain imaging at 9.4 T. Magn Reson Med. doi:10.1002/mrm.24726

    Google Scholar 

  20. Felder J, Hong SM, Celik A, Park J, Geschewski F, Jeong HB, Besançon E, Woo MK, Brenner D, Cho ZH, Shah NJ (2012) RF Coil array for accelerated excitation in three dimensions. In: Proceedings of the 20th scientific meeting, International Society for Magnetic Resonance in Medicine, Melbourne, p 2609

  21. Kozlov M, Turner R (2009) Fast MRI coil analysis based on 3-D electromagnetic and RF circuit co-simulation. J Magn Reson 200(1):147–152

    Article  PubMed  CAS  Google Scholar 

  22. Bitz AK, Kraff O, Orzada S, Maderwald S, Brote I, Johst S, Ladd ME (2011) Assessment of RF Safety of transmit coils at 7 T by experimental and numerical procedures. In: Proceedings of the 19th scientific meeting, International Society for Magnetic Resonance in Medicine, Montreal, p 490

  23. Gabriel C (1996) Compilation of the dielectric properties of body tissues at RF and microwave frequencies. Brooks air force technical report AL/OE-TR-1996-0037

  24. Christ A, Kainz W, Hahn EG, Honegger K, Zefferer M, Neufeld E, Rascher W, Janka R, Bautz W, Chen J, Kiefer B, Schmitt P, Hollenbach HP, Shen J, Oberle M, Szczerba D, Kam A, Guag JW, Kuster N (2010) The virtual family–development of surface-based anatomical models of two adults and two children for dosimetric simulations. Phys Med Biol 55(2):N23–N38

    Article  PubMed  Google Scholar 

  25. Beck BL, Jenkins KA, Rocca JR, Fitzsimmons JR (2004) Tissue-equivalent phantoms for high frequencies. Concept Magn Reson B 20B(1):30–33

    Article  Google Scholar 

  26. Chishti MH, Wang Z, Yeo DTB (2013) Local SAR prediction errors with variation of electrical properties in the head at 7T. In: Proceedings of the 21th scientific meeting, International Society for Magnetic Resonance in Medicine, Salt Lake City, p 2835

  27. Kozlov M, Shajan G, Turner R (2013) Effects of tuning condition, head size and position on the SAR of a 9.4T dual row array. In: Proceedings of the 21th scientific meeting, International Society for Magnetic Resonance in Medicine, Salt Lake City, p 2830

  28. Chung S, Kim D, Breton E, Axel L (2010) Rapid B1+ mapping using a preconditioning RF pulse with TurboFLASH readout. Magn Reson Med 64(2):439–446

    PubMed  PubMed Central  Google Scholar 

  29. Van de Moortele PF, Ugurbil K (2009) Very fast multi channel B1 calibration at high field in the small flip angle regime. In: Proceedings of the 17th scientific meeting, International Society for Magnetic Resonance in Medicine, Honolulu, p 367

  30. Metzger GJ, Snyder C, Akgun C, Vaughan T, Ugurbil K, Van de Moortele PF (2008) Local B1+ shimming for prostate imaging with transceiver arrays at 7T based on subject-dependent transmit phase measurements. Magn Reson Med 59(2):396–409

    Article  PubMed  Google Scholar 

  31. Yarnykh VL (2007) Actual flip-angle imaging in the pulsed steady state: a method for rapid three-dimensional mapping of the transmitted radiofrequency field. Magn Reson Med 57(1):192–200

    Article  PubMed  Google Scholar 

  32. Kirkpatrick S, Gelatt CD Jr, Vecchi MP (1983) Optimization by simulated annealing. Science 220(4598):671–680

    Article  PubMed  CAS  Google Scholar 

  33. Kozlov M, Turner R (2011) Analysis of RF transmit performance for a multi-row multi-channel MRI loop array at 300 and 400 MHz. In: Proceedings of the Asia-Pacific Microwave Conference, p 1193

  34. Curtis AT, Gilbert KM, Klassen LM, Gati JS, Menon RS (2012) Slice-by-slice B1+ shimming at 7 T. Magn Reson Med 68(4):1109–1116

    Article  PubMed  Google Scholar 

  35. Marques JP, Kober T, Krueger G, van der Zwaag W, Van de Moortele PF, Gruetter R (2010) MP2RAGE, a self bias-field corrected sequence for improved segmentation and T1-mapping at high field. Neuroimage 49(2):1271–1281

    Article  PubMed  Google Scholar 

  36. Hoffmann J, Budde J, Shajan G, Pohmann R (2010) Slice-selective B1 phase shimming at 9.4 T. In: Proceedings of the 18th scientific meeting, International Society for Magnetic Resonance in Medicine, Stockholm, p 1470

  37. Hurley AC, Al-Radaideh A, Bai L, Aickelin U, Coxon R, Glover P, Gowland PA (2010) Tailored RF pulse for magnetization inversion at ultrahigh field. Magn Reson Med 63(1):51–58

    PubMed  Google Scholar 

  38. Cloos MA, Boulant N, Luong M, Ferrand G, Giacomini E, Le Bihan D, Amadon A (2012) kT-points: short three-dimensional tailored RF pulses for flip-angle homogenization over an extended volume. Magn Reson Med 67(1):72–80

    Article  PubMed  CAS  Google Scholar 

  39. Eichfelder G, Gebhardt M (2011) Local specific absorption rate control for parallel transmission by virtual observation points. Magn Reson Med 66(5):1468–1476

    Article  PubMed  Google Scholar 

Download references

Author information

Authors and Affiliations

  1. High-Field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Spemannstr. 41, 72076, Tübingen, Germany

    Jens Hoffmann, Gunamony Shajan, Klaus Scheffler & Rolf Pohmann

  2. Graduate School of Neural and Behavioural Sciences, 72074, Tübingen, Germany

    Jens Hoffmann

  3. Department for Biomedical Magnetic Resonance, University of Tübingen, Hoppe-Seyler-Str. 3, 72076, Tübingen, Germany

    Klaus Scheffler

Authors
  1. Jens Hoffmann
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Gunamony Shajan
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Klaus Scheffler
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Rolf Pohmann
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Jens Hoffmann.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Hoffmann, J., Shajan, G., Scheffler, K. et al. 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 27, 373–386 (2014). https://doi.org/10.1007/s10334-013-0419-y

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s10334-013-0419-y

Keywords

Search

Navigation