title: Endovascular stents in pulmonary valve and artery in swine: feasibility study of MR imaging-guided deployment and postinterventional assessment.
abstract: OBJECTIVE
  To assess the feasibility of using magnetic resonance (MR) imaging to guide stent deployment in the pulmonary valve and artery and evaluate, after stent deployment, the position and morphology of and blood flow through the stent.
  
  
  METHODS
  Angiography and 1.5-T MR imaging were performed in a dual-imaging suite. Nitinol stents were placed in the pulmonary valve and main pulmonary artery in five pigs by using MR imaging guidance. For interactive MR imaging monitoring of catheter manipulation and stent delivery, balanced fast field-echo and T1-weighted turbo field-echo sequences were used. Visualization of the delivery system was based on T2* (with air as the contrast material) or T1 (with gadodiamide as the contrast material). After stent deployment, the position and morphology of and flow through the stent were verified with multiphase multisection balanced fast field-echo and velocity-encoded cine MR imaging. Findings at angiography and postmortem examination also helped verify stent placement. The paired Student t test was used for data analysis.
  
  
  RESULTS
  The stent was successfully deployed in all animals. The stent was placed distal to the pulmonary valve in four animals and across the pulmonary valve in one animal. The position and morphology of the stent were clearly depicted on balanced fast field-echo images. In the animal with the stent placed across the pulmonary valve, the pulmonary regurgitant fraction was 37%; this was not seen in the animals with stents placed distal to the pulmonary valve. No complication (eg, stent migration, intramural injury, or vascular perforation) was noted during the intervention. Findings at angiography and postmortem examination confirmed the position of the stents.
  
  
  CONCLUSIONS
  MR imaging has the potential to guide stent placement in the pulmonary valve or artery and to evaluate flow volume within the stent lumen after the intervention.
authors.affiliation: Department of Radiology, University of California San Francisco, 505 Parnassus Ave, L308, San Francisco, CA 94143-0628, USA.
authors.forename: Titus
authors.initials: T
authors.lastname: Kuehne
authors.forename: Maythem
authors.initials: M
authors.lastname: Saeed
authors.forename: Charles B
authors.initials: CB
authors.lastname: Higgins
authors.forename: Kelly
authors.initials: K
authors.lastname: Gleason
authors.forename: Gabriele A
authors.initials: GA
authors.lastname: Krombach
authors.forename: Oliver M
authors.initials: OM
authors.lastname: Weber
authors.forename: Alastair J
authors.initials: AJ
authors.lastname: Martin
authors.forename: Daniel
authors.initials: D
authors.lastname: Turner
authors.forename: David
authors.initials: D
authors.lastname: Teitel
authors.forename: Phillip
authors.initials: P
authors.lastname: Moore
mesh_terms: D000497:Alloys; D000818:Animals; D003287:Contrast Media; D005240:Feasibility Studies; D019786:Gadolinium DTPA; D018810:Magnetic Resonance Angiography; D008279:Magnetic Resonance Imaging; D011651:Pulmonary Artery; D011664:Pulmonary Valve; D015607:Stents; D013552:Swine
chemical_list: D000497:Alloys; D003287:Contrast Media; C013616:nitinol; C064925:gadodiamide; D019786:Gadolinium DTPA