title: Direct in vitro comparison of six three-dimensional positive contrast methods for susceptibility marker imaging.
abstract: OBJECTIVE
  To compare different techniques for positive contrast imaging of susceptibility markers with MRI for three-dimensional visualization. As several different techniques have been reported, the choice of the suitable method depends on its properties with regard to the amount of positive contrast and the desired background suppression, as well as other imaging constraints needed for a specific application.
  
  
  METHODS
  Six different positive contrast techniques are investigated for their ability to image at 3 Tesla a single susceptibility marker in vitro. The white marker method (WM), susceptibility gradient mapping (SGM), inversion recovery with on-resonant water suppression (IRON), frequency selective excitation (FSX), fast low flip-angle positive contrast SSFP (FLAPS), and iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) were implemented and investigated.
  
  
  RESULTS
  The different methods were compared with respect to the volume of positive contrast, the product of volume and signal intensity, imaging time, and the level of background suppression. Quantitative results are provided, and strengths and weaknesses of the different approaches are discussed.
  
  
  CONCLUSIONS
  The appropriate choice of positive contrast imaging technique depends on the desired level of background suppression, acquisition speed, and robustness against artifacts, for which in vitro comparative data are now available.
authors.affiliation: Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA. evertjan–isi.uu.nl
authors.forename: Evert-jan P A
authors.initials: EJ
authors.lastname: Vonken
authors.forename: Michael
authors.initials: M
authors.lastname: Schär
authors.forename: Jing
authors.initials: J
authors.lastname: Yu
authors.forename: Chris J G
authors.initials: CJ
authors.lastname: Bakker
authors.forename: Matthias
authors.initials: M
authors.lastname: Stuber
mesh_terms: D000465:Algorithms; D001921:Brain / Q000033:anatomy & histology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: off resonance; positive contrast; susceptibility imaging