title: Contrast-to-noise-ratio measurements in three-dimensional magnetic resonance angiography.
abstract: OBJECTIVE
  The authors report on the development and preliminary validation of a technique for measuring contrast-to-noise ratio (CNR) at all points along selected vessel segments in the original three-dimensional magnetic resonance angiography (MRA) dataset.
  
  
  METHODS
  Contrast-to-noise ratio dependencies on flow rate, field of view, and flip angle were measured on images from a conventional time-of-flight MRA pulse sequence using constant flow in a branching vascular phantom. An estimate of the inherent variability of the technique was obtained from multiple scans of a flow phantom and a human volunteer.
  
  
  RESULTS
  The overall standard deviation (SD) of the CNR was found to be approximately 6.1% of the average CNR value for the flow phantom study and 7.3% for the human study. Vessel CNR was found to increase with field of view and was found to become nonuniform for low flow rate and/or high flip angles.
  
  
  CONCLUSIONS
  In general, such CNR measurements allow the investigation of the mechanism of signal loss and general technique optimization in MRA.
authors.affiliation: Department of Physics, University of Utah, Salt Lake City.
authors.forename: Y
authors.initials: Y
authors.lastname: Du
authors.forename: D L
authors.initials: DL
authors.lastname: Parker
authors.forename: W L
authors.initials: WL
authors.lastname: Davis
authors.forename: D D
authors.initials: DD
authors.lastname: Blatter
mesh_terms: D001808:Blood Vessels / Q000033:anatomy & histology*; D002339:Carotid Arteries / Q000033:anatomy & histology; D002536:Cerebral Arteries / Q000033:anatomy & histology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008961:Models, Structural; D015203:Reproducibility of Results