Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Comparative Study
. 2016 Oct;76(4):1083-91.
doi: 10.1002/mrm.26022. Epub 2015 Oct 26.

Test-retest reproducibility of neurochemical profiles with short-echo, single-voxel MR spectroscopy at 3T and 7T

Melissa Terpstra  1 , Ian Cheong  1 , Tianmeng Lyu  2 , Dinesh K Deelchand  1 , Uzay E Emir  1 , Petr Bednařík  1   3   4 , Lynn E Eberly  2 , Gülin Öz  5
Affiliations
Comparative Study

Test-retest reproducibility of neurochemical profiles with short-echo, single-voxel MR spectroscopy at 3T and 7T

Melissa Terpstra et al. Magn Reson Med. 2016 Oct.

Abstract

Purpose: To determine the test-retest reproducibility of neurochemical concentrations obtained with a highly optimized, short-echo, single-voxel proton MR spectroscopy (MRS) pulse sequence at 3T and 7T using state-of-the-art hardware.

Methods: A semi-LASER sequence (echo time = 26-28 ms) was used to acquire spectra from the posterior cingulate and cerebellum at 3T and 7T from six healthy volunteers who were scanned four times weekly on both scanners. Spectra were quantified with LCModel.

Results: More neurochemicals were quantified with mean Cramér-Rao lower bounds (CRLBs) ≤20% at 7T than at 3T despite comparable frequency-domain signal-to-noise ratio. Whereas CRLBs were lower at 7T (P < 0.05), between-session coefficients of variance (CVs) were comparable at the two fields with 64 transients. Five metabolites were quantified with between-session CVs ≤5% at both fields. Analysis of subspectra showed that a minimum achievable CV was reached with a lower number of transients at 7T for multiple metabolites and that between-session CVs were lower at 7T than at 3T with fewer than 64 transients.

Conclusion: State-of-the-art MRS methodology allows excellent reproducibility for many metabolites with 5-min data averaging on clinical 3T hardware. Sensitivity and resolution advantages at 7T are important for weakly represented metabolites, short acquisitions, and small volumes of interest. Magn Reson Med 76:1083-1091, 2016. © 2015 Wiley Periodicals, Inc.

Keywords: 3 Tesla; 7 Tesla; coefficient of variation; spectroscopy; test-retest reproducibility.

PubMed Disclaimer

Figures

Figure 1
Figure 1. Reproducibility of spectral quality and pattern
All spectra obtained in one subject are shown (semi-LASER, TE = 28ms at 3T and 26ms at 7T, TR = 5s, 64 transients), with the 4 spectra obtained per brain region/field overlaid in each panel. The voxel locations are shown on the T1-weighted images acquired at 3T. Spectra were apodized with linebroadening (1 Hz) and Gaussian multiplication (σ = 0.12 s) for display purposes. PCC: posterior cingulate cortex, CBM: cerebellar vermis.
Figure 2
Figure 2. Mean metabolite concentrations, Cramér-Rao lower bounds (CRLB) and between-session CVs obtained with semi-LASER (TE = 28ms at 3T and 26ms at 7T, TR = 5s, 64 transients) in the two brain regions at both field strengths
Only metabolites with mean CRLB ≤ 20% are shown. Error bars represent inter-subject SD of intra-subject means. Means include all scans of each subject, i.e. up to 5 scans at each field strength. * p < 0.05, 3T vs. 7T.
Figure 3
Figure 3. Mean between-session CVs (SD/mean, top row) and inter-subject means of the intra-subject confidence interval widths for between-session CVs (bottom row) for posterior cingulate neurochemical profiles, obtained with 2, 3 or 4 repeat scans
Similar results were obtained for the CBM (not shown)
Figure 4
Figure 4. Mean between-session CVs obtained by averaging the first 2, 4, 8, 16, 32 and 64 transients (NEX) of spectra from the two brain regions and field strengths
Only metabolites that passed the CRLB reliability criteria are shown, e.g. weakly represented metabolites such as Asp, Gln, Tau and GSH are not reliably quantified in spectra with 2 transients.
See this image and copyright information in PMC

References

    1. Öz G, Alger JR, Barker PB, Bartha R, Bizzi A, Boesch C, Bolan PJ, Brindle KM, Cudalbu C, Dinçer A, Dydak U, Emir UE, Frahm J, González RG, Gruber S, Gruetter R, Gupta RK, Heerschap A, Henning A, Hetherington HP, Howe FA, Hüppi PS, Hurd RE, Kantarci K, Klomp DW, Kreis R, Kruiskamp MJ, Leach MO, Lin AP, Luijten PR, Marjańska M, Maudsley AA, Meyerhoff DJ, Mountford CE, Nelson SJ, Pamir MN, Pan JW, Peet AC, Poptani H, Posse S, Pouwels PJ, Ratai EM, Ross BD, Scheenen TW, Schuster C, Smith IC, Soher BJ, Tkáč I, Vigneron DB, Kauppinen RA Group TMC. Clinical proton MR spectroscopy in central nervous system disorders. Radiology. 2014;270(3):658–679. - PMC - PubMed
    1. Tkáč I, Öz G, Adriany G, Ugurbil K, Gruetter R. In vivo 1H NMR spectroscopy of the human brain at high magnetic fields: Metabolite quantification at 4T vs. 7T. Magn Reson Med. 2009;62(4):868–879. - PMC - PubMed
    1. Mekle R, Mlynárik V, Gambarota G, Hergt M, Krueger G, Gruetter R. MR spectroscopy of the human brain with enhanced signal intensity at ultrashort echo times on a clinical platform at 3T and 7T. Magn Reson Med. 2009;61(6):1279–1285. - PubMed
    1. Deelchand DK, Iltis I, Henry PG. Improved quantification precision of human brain short echo-time 1H magnetic resonance spectroscopy at high magnetic field: A simulation study. Magn Reson Med. 2014;72(1):20–25. - PMC - PubMed
    1. Brooks WM, Friedman SD, Stidley CA. Reproducibility of 1H-MRS in vivo. Magn Reson Med. 1999;41(1):193–197. - PubMed

MeSH terms