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Combined acquisition technique (CAT) for high-field neuroimaging with reduced RF power

  • Morwan Choli
  • Martin Blaimer
  • Felix A. Breuer
  • Philipp Ehses
  • Oliver Speck
  • Andreas J. Bartsch
  • Peter M. Jakob
Research Article

Abstract

Object

Clinical 3 T MRI systems are rapidly increasing and MRI systems with a static field of 7 T or even more have been installed. The RF power deposition is proportional to the square of the static magnetic field strength and is characterized by the specific absorption rate (SAR). Therefore, there exist defined safety limits to avoid heating of the patient. Here, we describe a hybrid method to significantly reduce the SAR compared to a turbo-spin-echo (TSE) sequence.

Materials and methods

We investigate the potential benefits of a combined acquisition technique (CAT) for high-field neuroimaging at 3 and 7 T. The TSE/EPI CAT experiments were performed on volunteers and patients and compared with standard TSE and GRASE protocols. Problems and solutions regarding T2 weighted CAT imaging are discussed.

Results

We present in vivo images with T2 and proton density contrast obtained on 3 and 7 T with significant SAR reduction (up to 60 %) compared with standard TSE. Image quality is comparable to TSE but CAT shows fewer artifacts than a GRASE sequence.

Conclusion

CAT is a promising candidate for neuroimaging at high fields up to 7 T. The SAR reduction allows one to shorten the waiting time between two excitations or to image more slices thereby reducing the overall measurement time.

Keywords

Hybrid imaging CAT SAR Dual bandwidth 

Notes

Acknowledgments

The authors thank Melisa Okanovic for providing the GRASE sequence. This work was funded by the German Research Association (DFG JA 827/9-1). Technical support was supplied by Siemens Medical, Erlangen, Germany. We thank the Leibniz Institute for Neurobiology in Magdeburg for access to the 7 T.

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Copyright information

© ESMRMB 2013

Authors and Affiliations

  • Morwan Choli
    • 1
  • Martin Blaimer
    • 1
  • Felix A. Breuer
    • 1
  • Philipp Ehses
    • 2
    • 3
  • Oliver Speck
    • 4
  • Andreas J. Bartsch
    • 5
    • 6
  • Peter M. Jakob
    • 1
    • 7
  1. 1.Research Center for Magnetic-Resonance-Bavaria (MRB)WürzburgGermany
  2. 2.Department of NeuroimagingUniversity Hospital TübingenTübingenGermany
  3. 3.Max Planck Institute for Biological CyberneticsTübingenGermany
  4. 4.Department of Experimental Physics (IEP)University of MagdeburgMagdeburgGermany
  5. 5.Department of NeuroradiologyUniversitätsklinikum HeidelbergHeidelbergGermany
  6. 6.FMRIB CentreUniversity of OxfordOxfordUK
  7. 7.Department of Experimental Physics 5University of WürzburgWürzburgGermany

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