title: Passive catheter visualization in magnetic resonance-guided endovascular therapy using multicycle projection dephasers.
abstract: OBJECTIVE
  To improve upon the conventional projection dephaser (PD) method of background suppression and evaluate the use of multicycle projection dephasers to improve catheter conspicuity in background-suppressed MR images.
  
  
  METHODS
  Passive visualization of endovascular catheters in MR images is compared using two background suppression techniques: 1) the conventional PD method and 2) the multicycle PD method. Contrast-filled 4-French (1.3 mm) catheters were imaged in homogeneous and heterogeneous phantoms, and in the common carotid artery of a canine using a modified spoiled gradient echo imaging sequence. We used catheter-to-background contrast (ranging from -100% to 100%) as the metric to compare background suppression techniques.
  
  
  RESULTS
  In the homogeneous and heterogeneous phantoms, the contrast was -6.9% (catheter darker than background) and 15.0%, respectively, using the conventional PD method, and 50.6% and 44.0%, respectively, using the multicycle PD method. In the canine carotid artery, the contrast was -3.1% using the conventional PD method and 53.0% using the multicycle PD method.
  
  
  CONCLUSIONS
  This work shows that multicycle projection dephasers improve catheter conspicuity over the conventional PD method. The multicycle PD method has potential for use in guiding endovascular procedures.
authors.affiliation: Department of Electrical and Computer Engineering, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Jonathan N
authors.initials: JN
authors.lastname: Draper
authors.forename: M Louis
authors.initials: ML
authors.lastname: Lauzon
authors.forename: Richard
authors.initials: R
authors.lastname: Frayne
mesh_terms: D000818:Animals; D001808:Blood Vessels / Q000473:pathology; D002404:Catheterization; D003198:Computer Simulation; D003287:Contrast Media / Q000494:pharmacology; D004285:Dogs; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging
chemical_list: D003287:Contrast Media