title: Motion-sensitized driven equilibrium for blood-suppressed T2* mapping.
abstract: OBJECTIVE
  To combine a motion-sensitized driven equilibrium (MSDE) preparation with a multi-echo spoiled gradient-echo sequence (SPGR) to suppress the blood signal intensity in T2* mapping of carotid plaques and liver.
  
  
  METHODS
  The analytical solution of the Bloch equations for the multi-echo SPGR sequence, with and without the MSDE preparation, was calculated to optimize sequence parameters. The sequence was implemented at 3 Tesla and T2* maps of carotid plaques and liver were first optimized for blood suppression, and then acquired from five healthy livers and six subjects with ultrasound-identified carotid plaques.
  
  
  RESULTS
  Simulations and experimental data showed that the flip angle that gives maximal signal (Ernst angle) in the MSDE-SPGR was greatly increased from that of pure SPGR. Robust blood suppression was obtained in the T2* maps of carotid plaques and liver, requiring suppression at a field of speed (FOS) of 30 cm/s in both the carotids and liver.
  
  
  CONCLUSIONS
  MSDE provides a means to suppress the blood signal intensity in SPGR sequences. Tissue T2* maps can be obtained without the confounding effects originating from blood vessels.
authors.affiliation: GSK Clinical Imaging Centre, Hammersmith Hospital, London, United Kingdom. rexford.newbould@gmail.com
authors.forename: Rexford D
authors.initials: RD
authors.lastname: Newbould
authors.forename: David R J
authors.initials: DR
authors.lastname: Owen
authors.forename: Joseph
authors.initials: J
authors.lastname: Shalhoub
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Brown
authors.forename: Giulio
authors.initials: G
authors.lastname: Gambarota
mesh_terms: D000465:Algorithms; D016477:Artifacts; D016893:Carotid Stenosis / Q000097:blood* / Q000473:pathology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008099:Liver / Q000033:anatomy & histology / Q000098:blood supply*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009038:Motion; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013382:Subtraction Technique