Contact

Sung-Tak Hong

Address: Spemannstr. 41
72076 Tübingen
Room number: 3.B.03
Fax: +49 7071 601 702

 

Picture of Hong, Sung-Tak

Sung-Tak Hong

Position: PhD Student  Unit: Alumni Scheffler

In vivo Proton Spectroscopy in the Rat Brain at 16.4 T


At ultra-high field, spectroscopy benefits not only from the increased SNR, but also from the increased spectral dispersion which reduces overlapping between different spectral lines and makes quantification easier and more accurate. At 16.4 T, MR-spectroscopy in the rat brain was implemented and optimized.

Goals
A technique for acquisition and analysis of in vivo proton spectroscopy in the rat brain is developed and optimized. In extensive studies, the accuracy, precision and practicability of this method is assessed.

Methods
Using an optimized STEAM sequence with ultra-short echo time and improved water suppression, in vivo spectra from voxels in the rat brain are acquired. Quantification is performed using an improved technique for taking macromolecular signals into account. To assess the quality of the information gained, additional studies investigated the inter- and intra-animal variability, the dependence of quantification precision on the number of averages and differences between different rat strains and brain regions.

Results
The developed technique made it possible to accurately quantify up to 20 metabolites in the rat brain, including acetate and glycine. Comparisons to published data from different field strengths showed a considerably improved accuracy and precision, even at relatively small numbers of averages. High-quality spectra could be obtained from all positions in the rat brain, including difficult regions like the cerebellum and the medulla oblongata, and differences between these structures were detected with high accuracy. Only small metabolic differences were found between rats of different strains.

 

In vivo proton spectra from different brain regions (hippocampus, thalamus, cerebellum and medulla oblongata). The concentration of up to 20 metabolites was possible in all compartments.

 

Conclusion
Spectroscopy benefits greatly from the increased SNR and spectral dispersion at ultra-high field. Quantifying up to 20 metabolites with a variability of less than 10%, this technique is capable of measuring a detailed metabolic profile within relatively short times and to detect even small variations in metabolite concentrations, making it a valuable method in preclinical and neuroscientific research, making it possible to detect changes caused by disease or by brain activation with high accuracy.




References
1.     S.-T. Hong, D. Balla, G. Shajan, C. Choi, K. Uğurbil, R. Pohmann (2011): Enhanced Neurochemical Profile of the Rat Brain using in vivo 1H NMR Spectroscopy at 16.4 T. Magn Reson Med 65, 28-34.
2.     S.-T. Hong, D. Balla, R. Pohmann (2011): Determination of regional variations and reproducibility in in vivo 1H NMR spectroscopy of the rat brain. Magn Reson Med 66, 11-17.
3.     S.-T. Hong, D. Balla, C. Choi, R. Pohmann (2011): Rat-strain dependent variations in brain metabolites detected by in vivo 1H NMR spectroscopy at 16.4 T. NMR Biomed 24, 1401-1407 (2011).

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Articles (5):

Hong S-T and Pohmann R (January-2013) Quantification issues of in vivo 1H NMR spectroscopy of the rat brain investigated at 16.4 T NMR in Biomedicine 26(1) 74–82.
Hong ST, Balla DZ, Choi C and Pohmann R (December-2011) Rat strain-dependent variations in brain metabolites detected by in vivo (1) H NMR spectroscopy at 16.4T NMR in Biomedicine 24(10) 1401-1407.
Hong S-T, Balla D and Pohmann R (July-2011) Determination of regional variations and reproducibility in in vivo (1) H NMR spectroscopy of the rat brain at 16.4 T Magnetic Resonance in Medicine 66(1) 11-17.
Hong S-T, Balla DZ, Shajan G, Choi C, Ugurbil K and Pohmann R (January-2011) Enhanced neurochemical profile of the rat brain using in vivo 1H NMR spectroscopy at 16.4 T Magnetic Resonance in Medicine 65(1) 28-34.
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Hong S-T, Choi C-B, Park C, Park C, Moon H-Y, Hong KS, Cheong C, Chae J-H and Choe B-Y (July-2009) Specific hippocampal choline decrease in an animal model of depression British Journal of Radiology 82(979) 549-533.

Conference papers (1):

Kim S-Y, Choi C-B, Lee S-H, Woo D-C, Lee H-S, Hong S-T, Kim H-Y and Choe B-Y (September-2009) 1H-MRS study of a depressive animal model for assessment of antidepressant effects, World Congress on Medical Physics and Biomedical Engineering 2009: Neuroengineering, Neural Systems, Rehabilitation and Prosthetics, Springer, Berlin, Germany, 275-278, Series: IFMBE Proceedings ; 25/9.

Posters (8):

Hong S-T, Balla DZ, Shajan G, Choi C, Ugurbil K and Pohmann R (May-5-2010): Localized in Vivo 1H NMR Spectroscopy of the Rat Brain at 16.4T, ISMRM-ESMRMB Joint Annual Meeting 2010, Stockholm, Sweden.
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Hoi C-B, Hong S-T, Kim S-Y, Woo D-C, Choe B-Y, Ryu K-N, Kang EH, Yim S-V, Lee D-W and Pohmann R (May-4-2010): Differential neurochemical responses in the rat striatum with isoflurane or ketamine/xylazine anesthesia: In vivo proton MRS study at 16.4 T, ISMRM-ESMRMB Joint Annual Meeting 2010, Stockholm, Sweden.
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Hong S-T, Choi C-B and Pohmann R (May-4-2010): Measurement of the Effects of Different Anesthetics in the Rat Thalamus by in Vivo 1H NMR Spectroscopy at 16.4T, ISMRM-ESMRMB Joint Annual Meeting 2010, Stockholm, Sweden.
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Hong S-T, Balla DZ, Shajan G, Choi C and Pohmann R (May-4-2010): Regional Variations of Metabolite Concentrations in the Rat Brain Assessed with in vivo 1H MR Spectroscopy at 16.4T, ISMRM-ESMRMB Joint Annual Meeting 2010, Stockholm, Sweden.
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Hong S-T, Balla DZ, Choi C and Pohmann R (May-3-2010): Evaluation of Minimum Scan Time for High Quality Quantitative in vivo 1H MR Spectroscopy at 16.4T, ISMRM-ESMRMB Joint Annual Meeting 2010, Stockholm, Sweden.
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Hong S-T, Balla DZ, Shajan G, Ugurbil K and Pohmann R (April-22-2009): Highly Accurate Quantification of Proton MR Spectroscopy in Rat Brain in Vivo at 16.4 T, 17th Annual Meeting of the International Society for Magnetic Resonance in Medicine (ISMRM 2009), Honolulu, HI, USA.
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Hong S-T, Choi C-B, Choe B-Y, Park C, Hong G and Chae J-H (May-6-2008): 1H MR Spectroscopic Measurement of Neurochemical Alterations in the Hippocampus of a Rat Model of Depression, 16th Scientific Meeting and Exhibition of the International Society of Magnetic Resonance in Medicine (ISMRM 2008), Toronto, Canada.
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Balla DZ, Hong S-T, Shajan G, Pohmann R and Ugurbil K (May-6-2008): Single Voxel MR Spectroscopy with Echo Times Below 2 ms at 16.4 T in the Rat Brain: First in vivo Results, 16th Scientific Meeting and Exhibition of the International Society of Magnetic Resonance in Medicine (ISMRM 2008), Toronto, Canada.
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Talks (1):

Hong S-T (May-4-2010) Invited Lecture: Regional Variations of Metabolite Concentrations in the Rat Brain by 1H NMR at 16.4 T, ISMRM-ESMRMB Joint Annual Meeting 2010, Stockholm, Sweden.

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Last updated: Tuesday, 18.11.2014