title: Stent appearance at contrast-enhanced MR angiography: in vitro examination with 14 stents.
abstract: OBJECTIVE
  To evaluate signal intensity changes influencing assessment of stent patency at contrast material-enhanced magnetic resonance (MR) angiography.
  
  
  METHODS
  By using an in vitro model, 14 stents-nine nitinol, one tantalum, two stainless steel, and two cobalt alloy-were investigated regarding their appearance at MR imaging. A vascular phantom consisting of tubes filled with 2.00 mmol/L gadopentetate dimeglumine in saline solution was studied in different orientations within the magnetic field. Imaging was performed with a fast three-dimensional gradient-echo sequence (4. 70/1.89 [repetition time msec/echo time msec]). Relative signal intensity reduction within the stents and the degree of artificial narrowing of the stent lumen were calculated.
  
  
  RESULTS
  The stent lumen was visible within 13 stents. A total signal void inside the stent lumen appeared in only one cobalt alloy stent. Artificial narrowing of the diameter was less than 33% in 10 of 14 stents. The tantalum stent and four nitinol stents seemed best suited for contrast-enhanced MR angiography. A bandlike artifact occurred at the ends of the stents when positioned along the readout direction.
  
  
  CONCLUSIONS
  To differentiate between artifacts and stenoses, knowledge of the degree of signal intensity reduction and artificial lumen narrowing within vascular stents is essential. Stent geometry, relative orientation to the magnetic field, and alloy composition influence signal intensity alteration within the stent lumen.
authors.affiliation: Department of Radiology, University of Regensburg, Klinikum, Franz-Josef-Strauss-Allee 11, D-93 042 Regensburg, Germany. Markus.Lenhart@klinik.uni-regensburg.de
authors.forename: M
authors.initials: M
authors.lastname: Lenhart
authors.forename: M
authors.initials: M
authors.lastname: Völk
authors.forename: C
authors.initials: C
authors.lastname: Manke
authors.forename: W R
authors.initials: WR
authors.lastname: Nitz
authors.forename: M
authors.initials: M
authors.lastname: Strotzer
authors.forename: S
authors.initials: S
authors.lastname: Feuerbach
authors.forename: J
authors.initials: J
authors.lastname: Link
mesh_terms: D003287:Contrast Media; D019786:Gadolinium DTPA; D006801:Humans; D007091:Image Processing, Computer-Assisted; D066298:In Vitro Techniques; D018810:Magnetic Resonance Angiography; D019047:Phantoms, Imaging; D015607:Stents; D014654:Vascular Patency
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA