title: Artifact-free in-stent lumen visualization by standard magnetic resonance angiography using a new metallic magnetic resonance imaging stent.
abstract: BACKGROUND
  Metallic stents cause susceptibility and radiofrequency artifacts on MR images, which, up to now, have not allowed for complete visualization of the stent lumen by MR angiography. The aim of this study was to investigate the potential of a new dedicated renal MRI stent for artifact-free in-stent lumen visualization in vitro and in a swine model.
  
  
  RESULTS
  In vitro investigations were performed with prototypes of balloon-expandable Aachen Resonance Renal MRI Stents dilated to diameters of 3 to 6 mm and placed in an aqueous gadolinium solution (1:25). Phase-contrast and contrast-enhanced T1-weighted gradient echo images were acquired. Renal MRI stents (n=12) were deployed in the renal arteries of 6 pigs. Renal arteries were examined with phase-contrast angiography and with flow measurements before and after stent placement in the stented area, respectively. Additionally, a contrast-enhanced, T1-weighted, spoiled-gradient echo sequence after administration of 0.2 mmol gadolinium-DTPA/kg body weight was performed after stent placement. The visibility of artifacts was analyzed on in vitro and in vivo images by two investigators who knew the stent positions. Stent positions were determined visually (in vitro) or by x-ray angiography (animal experiments). No artifacts were detected independent of the applied imaging sequence and the stent orientation to the main magnetic field.
  
  
  CONCLUSIONS
  The examined prototypes of fully MR-compatible MRI stents allow artifact-free visualization of the stent lumen with phase-contrast and contrast-enhanced T1-weighted angiography, as well as phase-contrast flow measurements in the stented area.
authors.affiliation: Clinic of Diagnostic Radiology, University of Technology Aachen, Germany. buecker@rad.rwth-aachen.de
authors.forename: Arno
authors.initials: A
authors.lastname: Buecker
authors.forename: Elmar
authors.initials: E
authors.lastname: Spuentrup
authors.forename: Alexander
authors.initials: A
authors.lastname: Ruebben
authors.forename: Rolf W
authors.initials: RW
authors.lastname: Günther
mesh_terms: D000818:Animals; D016477:Artifacts; D018810:Magnetic Resonance Angiography / Q000295:instrumentation*; D008670:Metals; D011859:Radiography; D012077:Renal Artery / Q000000981:diagnostic imaging; D015607:Stents; D013552:Swine
chemical_list: D008670:Metals