title: Two-dimensional parallel acquisition technique in 3D MR colonography.
abstract: OBJECTIVE
  In-vitro and in-vivo examinations to investigate the influence of one (1D)- and two-dimensional (2D) parallel acquisition techniques (PAT) on contrast-to-noise ratio (CNR) and image quality for bright-lumen 3D MR colonography.
  
  
  METHODS
  In-vitro measurements were performed on a 1.5 T whole-body MR scanner (MAGNETOM AVANTO(R), Siemens AG, Erlangen) with a standard spoiled 3D gradient-echo (3D GRE) sequence and a volume interpolated 3D GRE (VIBE) sequence using a home-built colon phantom. The relative CNR was determined and image quality evaluated for different acceleration factors (PAT factors). A bright-lumen 3D MR colonography with PAT factors 2, 3, 4 and 6 was performed on a 39-year-old volunteer. The 3D data sets were compared with regard to image quality.
  
  
  RESULTS
  The mean relative CNR values for the in-vitro measurements were 1, 0.81, 0.73, 0.52 and 0.4 (3D GRE) and 1, 0.8, 0.65, 0.45 and 0.3 (VIBE) for the PAT factors 1, 2, 3, 4 and 6, respectively. Residual aliasing artifacts not affecting image quality in a distinct manner were visible for 2D PAT, especially for the VIBE sequence. Increasing the PAT factor up to 6 and decreasing the acquisition time down to 10 seconds for the bright-lumen 3D MR colonography could achieve adequate image quality with significantly reduced image artifacts caused by peristalsis and pulsations.
  
  
  CONCLUSIONS
  Even for high PAT factors up to 6, 2D PAT only leads to a moderate CNR loss. For a 3D MR colonography, distinct shorter acquisition times can be achieved with identical resolution.
authors.affiliation: Sektion für Experimentelle Radiologie, Eberhard-Karls-Universität Tübingen. guenter.steidle@med.uni-tuebingen.de
authors.forename: G
authors.initials: G
authors.lastname: Steidle
authors.forename: J
authors.initials: J
authors.lastname: Schäfer
authors.forename: H P
authors.initials: HP
authors.lastname: Schlemmer
authors.forename: C D
authors.initials: CD
authors.lastname: Claussen
authors.forename: F
authors.initials: F
authors.lastname: Schick
mesh_terms: D003106:Colon / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D023881:Colonography, Computed Tomographic / Q000295:instrumentation / Q000379:methods*; D004867:Equipment Design; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D015203:Reproducibility of Results