title: In vivo proton T1 relaxation times of mouse myocardial metabolites at 9.4 T.
abstract: OBJECTIVE
  Proton magnetic resonance spectroscopy ((1) H-MRS) for quantitative in vivo assessment of mouse myocardial metabolism requires accurate acquisition timing to minimize motion artifacts and corrections for T1 -dependent partial saturation effects. In this study, mouse myocardial water and metabolite T1 relaxation time constants were quantified.
  
  
  METHODS
  Cardiac-triggered and respiratory-gated PRESS-localized (1) H-MRS was employed at 9.4 T to acquire signal from a 4-µL voxel in the septum of healthy mice (n = 10) while maintaining a steady state of magnetization using dummy scans during respiratory gates. Signal stability was assessed via standard deviations (SD) of zero-order phases and amplitudes of water spectra. Saturation-recovery experiments were performed to determine T1 values.
  
  
  RESULTS
  Phase SD did not vary for different repetition times (TR), and was 13.1° ± 4.5°. Maximal amplitude SD was 14.2% ± 5.1% at TR = 500 ms. Myocardial T1 values (mean ± SD) were quantified for water (1.71 ± 0.25 s), taurine (2.18 ± 0.62 s), trimethylamine from choline-containing compounds and carnitine (1.67 ± 0.25 s), creatine-methyl (1.34 ± 0.19 s), triglyceride-methylene (0.60 ± 0.15 s), and triglyceride-methyl (0.90 ± 0.17 s) protons.
  
  
  CONCLUSIONS
  This work provides in vivo quantifications of proton T1 values for mouse myocardial water and metabolites at 9.4 T.
authors: Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
authors: Adrianus J
authors: AJ
authors: Bakermans
authors: Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
authors: Desiree
authors: D
authors: Abdurrachim
authors: Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
authors: Tom R
authors: TR
authors: Geraedts
authors: Laboratory Genetic Metabolic Diseases, Department of Clinical Chemistry, and Department of Pediatrics, Emma Children's Hospital, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors: Sander M
authors: SM
authors: Houten
authors: Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
authors: Klaas
authors: K
authors: Nicolay
authors: Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.
authors: Jeanine J
authors: JJ
authors: Prompers
mesh_terms: D000818:Animals; D055424:Cardiac-Gated Imaging Techniques; D004562:Electrocardiography; D051379:Mice; D008810:Mice, Inbred C57BL; D009206:Myocardium / Q000378:metabolism*; D066244:Proton Magnetic Resonance Spectroscopy / Q000379:methods*; D055425:Respiratory-Gated Imaging Techniques
keywords: 1H-MRS; PRESS; metabolite T1 relaxation; mouse heart; myocardial metabolism; saturation-recovery