title: MRI may be sufficient for noninvasive assessment of great vessel stents: an in vitro comparison of MRI, CT, and conventional angiography.
abstract: OBJECTIVE
  The purpose of this study was to compare the diagnostic performance of MRI and CT assessment of great vessel stents in an in vitro model.
  
  
  METHODS
  Three contemporary great vessel stent materials (nitinol, platinum-iridium, and stainless steel) were assessed with three luminal conditions: no stenosis, internal stenosis, and external stenosis. Stents of the same material were implanted into an aorta model that was attached to an animal bypass pump with pulsatile flow. Each stent was imaged with conventional angiography as reference standard, 10 different MRI sequences, and CT. The sensitivity and specificity for the identification of stent stenosis was determined and stent lumen measurements compared.
  
  
  RESULTS
  Of the investigated MRI sequences, three had the highest overall sensitivity and specificity for the identification of stent stenosis in all studied materials: through-plane gradientrecalled echo (GRE) with 75° flip angle (100% and 95%, respectively), in- and through-plane steady-state free precession (SSFP) (99% and 90%) and MR angiography (MRA) with 75° flip angle (93% and 85%). Comparable sensitivity and specificity were achieved with CT (98% and 93%). GRE, SSFP, and MRA sequences tended to underestimate stent lumen diameter in externally nonstenosed stents and overestimate diameter in internally stenosed stents (p < 0.05). CT slightly underestimated external stenoses in all stent types (p < 0.05).
  
  
  CONCLUSIONS
  Defined MRI sequences are feasible to assess nitinol, platinum-iridium, and stainless steel great vessel stents with diagnostic performance comparable with CT.
authors.affiliation: Cardiorespiratory Unit, Great Ormond Street Hospital for Children, NHS Trust, London WC1N 3JH, United Kingdom.
authors.forename: Johannes
authors.initials: J
authors.lastname: Nordmeyer
authors.forename: Régis
authors.initials: R
authors.lastname: Gaudin
authors.forename: Oliver R
authors.initials: OR
authors.lastname: Tann
authors.forename: Phillip C
authors.initials: PC
authors.lastname: Lurz
authors.forename: Phillip
authors.initials: P
authors.lastname: Bonhoeffer
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Taylor
authors.forename: Vivek
authors.initials: V
authors.lastname: Muthurangu
mesh_terms: D000792:Angiography / Q000379:methods*; D000818:Animals; D001011:Aorta; D066298:In Vitro Techniques; D008279:Magnetic Resonance Imaging; D012680:Sensitivity and Specificity; D015607:Stents; D013552:Swine; D014057:Tomography, X-Ray Computed