title: High-resolution whole-body magnetic resonance imaging applications at 1.5 and 3 Tesla: a comparative study.
abstract: OBJECTIVE
  To analyze the impact of altered magnetic field properties on image quality and on potential artifacts when an established whole-body magnetic resonance imaging (WB-MRI) protocol at 1.5 Tesla (T) is migrated to 3 T.
  
  
  METHODS
  Fifteen volunteers underwent noncontrast magnetic resonance imaging (MRI) on 32-channel whole body-scanners at 1.5 and 3 T with the use of parallel acquisition techniques (PAT). Coronal T1-weighted TSE- and short tau inversion recovery (STIR)-sequences at 4 body levels including sagittal imaging of the whole spine were performed. Additional axial HASTE-imaging of lung and abdomen, T1-/T2-weighted-TSE- and EPI-sequences of the brain and T2-weighted respiratory-triggered imaging of the liver was acquired. Both data sets were compared by 2 independent readers in respect to artifacts and image quality using a 5-point scale. Regions of pronounced artifacts were defined.
  
  
  RESULTS
  Overall image impression was both qualitatively rated as "good" at 1.5 and 3 T for T1-w-TSE- and STIR-imaging of the whole body and spine. At 1.5 T, significantly better quantitative values for overall image quality were found for WB-STIR, T2-w-TSE imaging of the liver and brain (Wilcoxon Mann-Whitney U Test; P < 0.05), overall rated as good at 3 T. Significantly higher dielectric effects at 3 T were affecting T1-w- and STIR-WB-MRI, and HASTE of the abdomen and better image homogeneity at 1.5 T was observed for T1-weighted-/STIR-WB-MRI and T1-w-TSE-imaging of the spine. Pulsation artifacts were significantly increased at 3 T for T1-w WB-MRI. Significantly higher susceptibility artifacts were found for GRE-sequences of the brain at 3 T. Motion artifacts, Gibbs-Ringing, and image distortion was not significantly different and showed slightly higher quantitative values at 3 T (except for HASTE imaging of the abdomen). Overall scan time was 45 minutes and 44 seconds at 1.5 T and 40 minutes and 28 seconds at 3 T at identical image resolution.
  
  
  CONCLUSIONS
  Three Tesla WB-MRI is feasible with good image quality comparable to 1.5 T. 3.0 T WB-MRI shows significantly more artifacts with a mild to moderate impact on image assessment. Therefore 1.5 T WB-MRI is the preferred image modality. Overall scan time at 3 T is reduced with the use of parallel imaging at a constant image resolution.
authors.affiliation: Institute of Clinical Radiology, University Hospitals Munich-Grosshadern, LMU, Munich, Germany. gerwin.schmidt@med.uni-muenchen.de
authors.forename: Gerwin P
authors.initials: GP
authors.lastname: Schmidt
authors.forename: Bernd
authors.initials: B
authors.lastname: Wintersperger
authors.forename: Anno
authors.initials: A
authors.lastname: Graser
authors.forename: Andrea
authors.initials: A
authors.lastname: Baur-Melnyk
authors.forename: Maximilian F
authors.initials: MF
authors.lastname: Reiser
authors.forename: Stefan O
authors.initials: SO
authors.lastname: Schoenberg
mesh_terms: D000328:Adult; D016477:Artifacts; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D018709:Statistics, Nonparametric; D051598:Whole Body Imaging