title: Multivendor implementation and comparison of volumetric whole-brain echo-planar MR spectroscopic imaging.
abstract: OBJECTIVE
  To assess volumetric proton MR spectroscopic imaging (MRSI) of the human brain on multivendor MRI instruments.
  
  
  METHODS
  Echo-planar spectroscopic imaging was developed on instruments from three manufacturers, with matched specifications and acquisition protocols that accounted for differences in sampling performance, radiofrequency (RF) power, and data formats. Intersite reproducibility was evaluated for signal-normalized maps of N-acetylaspartate (NAA), creatine (Cre), and choline using phantom and human subject measurements. Comparative analyses included metrics for spectral quality, spatial coverage, and mean values in atlas-registered brain regions.
  
  
  RESULTS
  Intersite differences for phantom measurements were less than 1.7% for individual metabolites and less than 0.2% for ratio measurements. Spatial uniformity ranged from 79% to 91%. The human studies found differences of mean values in the temporal lobe, but good agreement in other white matter regions, with maximum differences relative to their mean of under 3.2%. For NAA/Cre, the maximum difference was 1.8%. In gray matter, a significant difference was observed for frontal lobe NAA. Primary causes of intersite differences were attributed to shim quality, B0 drift, and accuracy of RF excitation. Correlation coefficients for measurements at each site were over 0.60, indicating good reliability.
  
  
  CONCLUSIONS
  A volumetric intensity-normalized MRSI acquisition can be implemented in a comparable manner across multivendor MR instruments.
authors.affiliation: Department of Radiology, University of Miami, Miami, Florida, USA.|Department of Radiology, University of Calgary, Calgary, Canada.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Sabati
authors.affiliation: Department of Radiology, University of Miami, Miami, Florida, USA.
authors.forename: Sulaiman
authors.initials: S
authors.lastname: Sheriff
authors.affiliation: Department of Radiology, Stanford University, Stanford, California, USA.
authors.forename: Meng
authors.initials: M
authors.lastname: Gu
authors.affiliation: The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, and the F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA.
authors.forename: Juan
authors.initials: J
authors.lastname: Wei
authors.affiliation: The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, and the F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA.
authors.forename: Henry
authors.initials: H
authors.lastname: Zhu
authors.affiliation: The Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, and the F.M. Kirby Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, Maryland, USA.
authors.forename: Peter B
authors.initials: PB
authors.lastname: Barker
authors.affiliation: Department of Radiology, Stanford University, Stanford, California, USA.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Spielman
authors.affiliation: Neurology and Radiological Sciences, University of California, Los Angeles, California, USA.
authors.forename: Jeffry R
authors.initials: JR
authors.lastname: Alger
authors.affiliation: Department of Radiology, University of Miami, Miami, Florida, USA.
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Maudsley
mesh_terms: D000328:Adult; D001921:Brain / Q000033:anatomy & histology* / Q000502:physiology*; D001923:Brain Chemistry / Q000502:physiology; D001931:Brain Mapping / Q000379:methods*; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D019047:Phantoms, Imaging; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult
keywords: MR spectroscopic imaging; MR standardization; clinical equivalency; multicenter studies; quantitative mapping