title: Influence of macromolecule baseline on1H MR spectroscopic imaging reproducibility.
abstract: Poorly characterized macromolecular (MM) and baseline artefacts are known to reduce metabolite quantitation accuracy in1H MR spectroscopic imaging (MRSI). Increasing echo time (TE) and improvements in MM analysis schemes have both been proposed as strategies to improve metabolite measurement reliability. In this study, the influence of TE and two MM analysis schemes on MRSI reproducibility are investigated.
  
  
  
  An experimentally acquired baseline was collected using an inversion recovery sequence (TI = 750 ms) and incorporated into the analysis method. Intrasubject reproducibility of MRSI scans, acquired at 3 Tesla, was assessed using metabolite coefficients of variance (COVs) for both experimentally acquired and simulated MM analysis schemes. In addition, the reproducibility of TE = 35 ms, 80 ms, and 144 ms was evaluated.
  
  
  
  TE = 80 ms was the most reproducible for singlet metabolites with COVs < 6% for total N-acetyl-aspartate, total creatine, and total choline; however, moderate multiplet dephasing was observed. Analysis incorporating the experimental baseline achieved higher Glu and Glx reproducibility at TE = 35 ms, and showed improvements over the simulated baseline, with higher efficacy for poorer data.
  
  
  
  Overall, TE = 80 ms yielded the most reproducible singlet metabolite estimates. However, combined use of a short TE sequence and the experimental baseline may be preferred as a compromise between accuracy, multiplet dephasing, and T2 bias on metabolite estimates. Magn Reson Med 77:34-43, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.
authors.affiliation: PSIBS Doctoral Training Centre, University of Birmingham, United Kingdom.|Birmingham University Imaging Centre (BUIC), School of Psychology, University of Birmingham, United Kingdom.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Birch
authors.affiliation: Department of Oncology, Birmingham Children's Hospital NHS Foundation Trust, Birmingham, United Kingdom.|School of Cancer Sciences, University of Birmingham, United Kingdom.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Peet
authors.affiliation: School of Computer Science, University of Birmingham, Kingdom.
authors.forename: Hamid
authors.initials: H
authors.lastname: Dehghani
authors.affiliation: Birmingham University Imaging Centre (BUIC), School of Psychology, University of Birmingham, United Kingdom.
authors.forename: Martin
authors.initials: M
authors.lastname: Wilson
mesh_terms: D000328:Adult; D000465:Algorithms; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism; D003337:Corpus Callosum / Q000000981:diagnostic imaging / Q000378:metabolism; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D046911:Macromolecular Substances / Q000737:chemistry / Q000378:metabolism*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015203:Reproducibility of Results; D055815:Young Adult
chemical_list: D046911:Macromolecular Substances
keywords: MRSI; TE; baseline; macromolecule; reproducibility