title: Quality of 186 child brain spectra using motion and B0 shim navigated single voxel spectroscopy.
abstract: OBJECTIVE
  To evaluate B0 shim and motion navigated single voxel spectroscopy in children. Assess the repeatability of metabolite concentrations in three regions: medial frontal grey matter, peritrigonal white matter, and basal ganglia. Determine the extent of intra- and interacquisition movement in this population.
  
  
  METHODS
  Linewidth and signal to noise ratio were calculated to assess spectral quality of 186 spectra at 3 Tesla. Repeatability was assessed on 31 repeat scans. Navigator images were used to assess localization errors, while navigator motion and shim logs were used to demonstrate the efficacy of correction needed during the scans.
  
  
  RESULTS
  Average linewidths ± standard deviations of N-acetyl aspartate are 3.8 ± 0.6 Hz, 4.4 ± 0.5 Hz, and 4.7 ± 0.8 Hz in each region, respectively. Scan-to-scan measurement variance in metabolite concentrations closely resembled the expected variance. A total of 73% and 32% of children moved before and during the acquisition, causing a voxel shift of more than 10% of the voxel volume, 1.5 mm. The predominant movement directions were sliding out of the coil and nodding (up-down rotation). First-order B0 corrections were significant (>10 μT/m) in 18 % of acquisitions.
  
  
  CONCLUSIONS
  Prospective motion and B0 correction provides high quality repeatable spectra. The study found that most children moved between acquisitions and a substantial number moved during acquisitions.
authors.affiliation: Oxford Centre for Clinical Magnetic Resonance Research (OCMR), Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom.
authors.forename: Aaron T
authors.initials: AT
authors.lastname: Hess
authors.forename: André J W
authors.initials: AJ
authors.lastname: van der Kouwe
authors.forename: Kenneth K
authors.initials: KK
authors.lastname: Mbugua
authors.forename: Barbara
authors.initials: B
authors.lastname: Laughton
authors.forename: Ernesta M
authors.initials: EM
authors.lastname: Meintjes
mesh_terms: D000465:Algorithms; D016477:Artifacts; D001921:Brain / Q000378:metabolism*; D002675:Child, Preschool; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D009068:Movement; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: B0 correction; motion correction; navigator; single voxel spectroscopy