title: Delivery and assessment of endovascular stents to repair aortic coarctation using MR and X-ray imaging.
abstract: OBJECTIVE
  To investigate the utility of MR and X-ray imaging for characterizing aortic coarctation and flow, and guiding the endovascular catheter to place a stent to repair the coarctation.
  
  
  METHODS
  The descending aorta in eight dogs was looped with elastic band and tightened distal to the subclavian artery. Balanced fast field echo (bFFE) and velocity-encoded cine (VEC) MRI sequences were used for device tracking and measuring aortic flow. A T1-weighted fast-field echo sequence (T1-FFE) was used to visualize the coarctation and roadmap the aorta. Nitinol stents were guided by a nitinol guidewire and placed under MR guidance.
  
  
  RESULTS
  Aortic coarctation was visible on MR and X-ray imaging. The procedure success rate was 88%. VEC MRI measured the changes in aortic flow (baseline = 1.3 +/- 0.2, coarctation = 0.2 +/- 0.02, and stent placement = 0.8 +/- 0.1 liters/minute). A significant reduction in iliac blood pressure was measured after coarctation, but it was reversed by stent placement. The stent lumen was visible on X-ray fluoroscopy, but not on MRI.
  
  
  CONCLUSIONS
  Stent deployment to repair aortic coarctation is feasible under MR guidance. The combined use of MR and X-ray imaging is effective for anatomic and functional evaluation of aortic coarctation dilation, which may be crucial for optimal therapy.
authors.affiliation: Department of Radiology, University of California-San Francisco, California 94143-0628, USA. maythem.saeed@radiology.ucsf.edu
authors.forename: Maythem
authors.initials: M
authors.lastname: Saeed
authors.forename: Christine B
authors.initials: CB
authors.lastname: Henk
authors.forename: Oliver
authors.initials: O
authors.lastname: Weber
authors.forename: Alastair
authors.initials: A
authors.lastname: Martin
authors.forename: Mark
authors.initials: M
authors.lastname: Wilson
authors.forename: Kendrick
authors.initials: K
authors.lastname: Shunk
authors.forename: David
authors.initials: D
authors.lastname: Saloner
authors.forename: Charles B
authors.initials: CB
authors.lastname: Higgins
mesh_terms: D000497:Alloys; D000704:Analysis of Variance; D000818:Animals; D001017:Aortic Coarctation / Q000000981:diagnostic imaging / Q000628:therapy*; D003287:Contrast Media / Q000008:administration & dosage; D004285:Dogs; D005240:Feasibility Studies; D005471:Fluoroscopy; D019786:Gadolinium DTPA / Q000008:administration & dosage; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015641:Radiography, Interventional; D015607:Stents
chemical_list: D000497:Alloys; D003287:Contrast Media; C013616:nitinol; D019786:Gadolinium DTPA