Optimization of Keyhole Imaging Parameters for Glutamate Chemical Exchange Saturation Transfer MRI at 7.0 T

  • 70 Accesses



To evaluate the effects of a reference image and keyhole factor (Kf) selections for high-frequency substitution on keyhole imaging technique for applications in glutamate chemical exchange saturation transfer (GluCEST) imaging.


The CEST data were obtained using a 7.0 T MRI scanner. We used varied Kf ranges that constituted from 16.67 to 75 % of the full k-space. The reference image was respectively selected for − 3 and + 3 ppm images that associated with the GluCEST calculation and the unsaturated image. The zero-padding algorithm was applied for the missing k-space lines in the low-frequency data collected to compare the results obtained from using the keyhole imaging technique. All the techniques were evaluated using a healthy rat group and extended to the status epilepticus rat group to explore their applicability and usability.


The calculated GluCEST signals and visually inspected results from the reconstructed GluCEST maps indicated that the combination of unsaturated image as a reference image, and over 50 % of Kf showed consistent signals and image quality compared with the fully sampled CEST data.


Combining the keyhole imaging technique with GluCEST imaging enables stable image reconstruction and quantitative evaluation, and this approach is potentially applicable in various CEST imaging applications.

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

Access options

Buy single article

Instant unlimited access to the full article PDF.

US$ 39.95

Price includes VAT for USA

Subscribe to journal

Immediate online access to all issues from 2019. Subscription will auto renew annually.

US$ 99

This is the net price. Taxes to be calculated in checkout.

Fig. 1.
Fig. 2.
Fig. 3.
Fig. 4.
Fig. 5.


  1. 1.

    Dula AN, Smith SA, Gore JC (2013) Application of chemical exchange saturation transfer (CEST) MRI for endogenous contrast at 7 tesla. J Neuroimaging 23:526–532

  2. 2.

    Jones KM, Pollard AC, Pagel MD (2018) Clinical applications of chemical exchange saturation transfer (CEST) MRI. J Magn Reson Imaging 47:11–27

  3. 3.

    van Zijl PCM, Yadav NN (2011) Chemical exchange saturation transfer (CEST): what is in a name and what isn’t? Magn Reson Med 65:927–948

  4. 4.

    Zhou J, Blakeley JO, Hua J et al (2008) Practical data acquisition method for human brain tumor amide proton transfer (APT) imaging. Magn Reson Med 60:842–849

  5. 5.

    Lustig M, Donoho D, Pauly JM (2007) Sparse MRI: the application of compressed sensing for rapid MR imaging. Magn Reson Med 58:1182–1195

  6. 6.

    Hu X (1994) On the “keyhole” technique. J Magn Reson Imaging 4:231

  7. 7.

    Hu X, Parrish T (1994) Reduction of field of view for dynamic imaging. Magn Reson Med 31:691–694

  8. 8.

    She H, Greer JS, Zhang S et al (2019) Accelerating chemical exchange saturation transfer MRI with parallel blind compressed sensing. Magn Reson Med 81:504–513

  9. 9.

    Jaspan ON, Fleysher R, Lipton ML (2015) Compressed sensing MRI: a review of the clinical literature. Br J Radiol 88:20150487

  10. 10.

    Heo HY, Zhang Y, Lee DH, Jiang S, Zhao X, Zhou J (2017) Accelerating chemical exchange saturation transfer (CEST) MRI by combining compressed sensing and sensitivity encoding techniques. Magn Reson Med 77:779–786

  11. 11.

    Varma G, Lenkinski RE, Vinogradov E (2012) Keyhole chemical exchange saturation transfer. Magn Reson Med 68:1228–1233

  12. 12.

    Cai KJ, Haris M, Singh A et al (2012) Magnetic resonance imaging of glutamate. Nat Med 18:302–306

  13. 13.

    Singh A, Cai KJ, Haris M, Hariharan H, Reddy R (2013) On B1 inhomogeneity correction of in vivo human brain glutamate chemical exchange saturation transfer contrast at 7T. Magn Reson Med 69:818–824

  14. 14.

    Du YP, Parker DL, Davis WL, Cao G (1994) Reduction of partial-volume artifacts with zero-filled interpolation in three-dimensional MR angiography. J Magn Reson Imaging 4:733–741

  15. 15.

    Lee DH, Lee DW, Kwon JI et al (2019) In vivo mapping and quantification of creatine using chemical exchange saturation transfer imaging in rat models of epileptic seizure. Mol Imaging Biol 21:232–239

  16. 16.

    Sperk G (1994) Kainic acid seizures in the rat. Prog Neurobiol 42:1–32

  17. 17.

    Park J, Zhang Q, Jellus V, Simonetti O, Li D (2005) Artifact and noise suppression in GRAPPA imaging using improved k-space coil calibration and variable density sampling. Magn Reson Med 53:186–193

  18. 18.

    Xiao Z, Hoge WS, Mulkern RV, Zhao L, Hu G, Kyriakos WE (2008) Comparison of parallel MRI reconstruction methods for accelerated 3D fast spin-echo imaging. Magn Reson Med 60:650–660

  19. 19.

    Mogatadakala KV, Bankson JA, Narayana PA (2008) Three-element phased-array coil for imaging of rat spinal cord at 7T. Magn Reson Med 60:1498–1505

  20. 20.

    Herrmann KH, Schmidt S, Kretz A et al (2012) Possibilities and limitations for high resolution small animal MRI on a clinical whole-body 3T scanner. Magn Reson Mater Phy 25:233–244

  21. 21.

    Lee DH, Lee DW, Kwon JI et al (2019) Retrospective brain motion correction in glutamate chemical exchange saturation transfer (GluCEST) MRI. Mol Imaging Biol 21:1064–1070

  22. 22.

    Davis KA, Nanga RPR, Das S et al (2015) Glutamate imaging (GluCEST) lateralizes epileptic foci in nonlesional temporal lobe epilepsy. Sci Transl Med 7(309):309ra161.

  23. 23.

    Jones CK, Polders D, Hua J et al (2012) In vivo three-dimensional whole-brain pulsed steady-state chemical exchange saturation transfer at 7 T. Magn Reson Med 67:1579–1589

  24. 24.

    Zaiss M, Xu JZ, Goerke S et al (2014) Inverse Z-spectrum analysis for spillover-, MT-, and T-1-corrected steady-state pulsed CEST-MRI - application to pHweighted MRI of acute stroke. NMR Biomed 27:240–252

Download references

Author information

Correspondence to Dong-Hoon Lee or Dong-Cheol Woo.

Ethics declarations

Conflict of Interest

The authors of this manuscript declare that they have no conflicts of interest.

Additional information

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Lee, D., Lee, D., Woo, C. et al. Optimization of Keyhole Imaging Parameters for Glutamate Chemical Exchange Saturation Transfer MRI at 7.0 T. Mol Imaging Biol (2019).

Download citation

Key Words

  • Keyhole imaging
  • Keyhole parameter
  • Glutamate
  • Chemical exchange saturation transfer