title: Automatic voxel positioning for MRS at 7 T.
abstract: OBJECTIVE
  The purpose of this study was to test, for the first time, whether spectroscopy voxels could be positioned automatically with high accuracy and reproducibility in ultrahigh-field longitudinal magnetic resonance spectroscopy (MRS) studies.
  
  
  METHODS
  MRS voxels were automatically positioned in two cingulate subregions of 12 healthy subjects using a vendor-provided automatic voxel positioning (AutoAlign) technique, and were manually placed in the same regions of 10 healthy subjects by an experienced technician in three 7 T MRS scan sessions. Different coils were used for manual (24-channel coil) and automatic (32-channel coil) voxel placement, and the effects of signal-to-noise-ratio differences on the spectra were considered.
  
  
  RESULTS
  Over three scan sessions and two regions scanned for each subject, a mean voxel geometric overlap ratio of 0.91 for automatic positioning reflected accurate voxel alignment, while the geometric overlap ratio was only 0.70 for voxels placed manually. Comparable voxel positions among the three scan sessions (p > 0.05) indicated high reproducibility of automatic voxel alignment. In comparison, significant voxel displacement among scan sessions (p < 0.05) was found using manual voxel positioning.
  
  
  CONCLUSIONS
  In view of the highly accurate and reproducible voxel alignment with automatic voxel positioning, we propose the application of automatic rather than manual voxel positioning in future ultrahigh-field longitudinal MRS studies.
authors.affiliation: Faculty for Natural Sciences, Biomedical Magnetic Resonance, Otto-von-Guericke University, ZENIT Building, Leipziger Str. 44, 39120, Magdeburg, Germany.
authors.forename: Weiqiang
authors.initials: W
authors.lastname: Dou
authors.forename: Oliver
authors.initials: O
authors.lastname: Speck
authors.forename: Thomas
authors.initials: T
authors.lastname: Benner
authors.forename: Jörn
authors.initials: J
authors.lastname: Kaufmann
authors.forename: Meng
authors.initials: M
authors.lastname: Li
authors.forename: Kai
authors.initials: K
authors.lastname: Zhong
authors.forename: Martin
authors.initials: M
authors.lastname: Walter
mesh_terms: D000328:Adult; D005260:Female; D006179:Gyrus Cinguli / Q000033:anatomy & histology* / Q000737:chemistry*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D057054:Molecular Imaging / Q000379:methods; D010363:Pattern Recognition, Automated / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique