In vivo macromolecule signals in rat brain 1H-MR spectra at 9.4T: Parametrization, spline baseline estimation, and T2 relaxation times

Dunja Simicic, Veronika Rackayova, Lijing Xin, Ivan Tkáč, Tamas Borbath, Zenon Starcuk, Jana Starcukova, Bernard Lanz, Cristina Cudalbu

Research output: Contribution to journalArticlepeer-review

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Abstract

Purpose: Reliable detection and fitting of macromolecules (MM) are crucial for accurate quantification of brain short-echo time (TE) 1H-MR spectra. An experimentally acquired single MM spectrum is commonly used. Higher spectral resolution at ultra-high field (UHF) led to increased interest in using a parametrized MM spectrum together with flexible spline baselines to address unpredicted spectroscopic components. Herein, we aimed to: (1) implement an advanced methodological approach for post-processing, fitting, and parametrization of 9.4T rat brain MM spectra; (2) assess the concomitant impact of the LCModel baseline and MM model (ie, single vs parametrized); and (3) estimate the apparent T2 relaxation times for seven MM components. Methods: A single inversion recovery sequence combined with advanced AMARES prior knowledge was used to eliminate the metabolite residuals, fit, and parametrize 10 MM components directly from 9.4T rat brain in vivo 1H-MR spectra at different TEs. Monte Carlo simulations were also used to assess the concomitant influence of parametrized MM and DKNTMN parameter in LCModel. Results: A very stiff baseline (DKNTMN ≥ 1 ppm) in combination with a single MM spectrum led to deviations in metabolite concentrations. For some metabolites the parametrized MM showed deviations from the ground truth for all DKNTMN values. Adding prior knowledge on parametrized MM improved MM and metabolite quantification. The apparent T2 ranged between 12 and 24 ms for seven MM peaks. Conclusion: Moderate flexibility in the spline baseline was required for reliable quantification of real/experimental spectra based on in vivo and Monte Carlo data. Prior knowledge on parametrized MM improved MM and metabolite quantification.

Original languageEnglish (US)
Pages (from-to)2384-2401
Number of pages18
JournalMagnetic resonance in medicine
Volume86
Issue number5
Early online dateJul 15 2021
DOIs
StatePublished - Nov 2021

Bibliographical note

Funding Information:
Financial support was provided by the Swiss National Science Foundation (project no 310030_173222; DS, VR, CC), National Institutes of Health grants (P41 EB027061 and P30 NS076408; IT), Horizon 2020/ CDS-QUAMRI Grant number: 634541 (TB), the European Regional Development Fund (MEYS CZ.02.1.01/0.0/0.0/16_013/0001775; ZS, JS). The authors acknowledge access to the facilities and expertise of the CIBM Center for Biomedical Imaging, a Swiss research center of excellence founded and supported by Lausanne University Hospital (CHUV), University of Lausanne (UNIL), Ecole Polytechnique F?d?rale de Lausanne (EPFL), University of Geneva (UNIGE), and Geneva University Hospitals (HUG). The authors would like to thank Professors S. R. Williams and Anke Henning for constructive discussions.

Funding Information:
Financial support was provided by the Swiss National Science Foundation (project no 310030_173222; DS, VR, CC), National Institutes of Health grants (P41 EB027061 and P30 NS076408; IT), Horizon 2020/ CDS‐QUAMRI Grant number: 634541 (TB), the European Regional Development Fund (MEYS CZ.02.1.01/0.0/0.0/16_013/0001775; ZS, JS). The authors acknowledge access to the facilities and expertise of the CIBM Center for Biomedical Imaging, a Swiss research center of excellence founded and supported by Lausanne University Hospital (CHUV), University of Lausanne (UNIL), Ecole Polytechnique Fédérale de Lausanne (EPFL), University of Geneva (UNIGE), and Geneva University Hospitals (HUG). The authors would like to thank Professors S. R. Williams and Anke Henning for constructive discussions.

Publisher Copyright:
© 2021 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals LLC on behalf of International Society for Magnetic Resonance in Medicine

Keywords

  • H-MRS
  • UHF
  • baseline
  • fitting
  • macromolecules
  • parametrization
  • rat brain
  • relaxation times

PubMed: MeSH publication types

  • Journal Article
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

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