title: Perceptibility and quantification of in-stent stenosis with six peripheral arterial stent types in vitro: comparison of 16-MDCT angiography, 64-MDCT angiography, and MR angiography.
abstract: OBJECTIVE
  The purpose of this study was to evaluate and compare the perceptibility of 75% and 95% in-stent stenoses with CT angiography and MR angiography using six stent types in a phantom model.
  
  
  METHODS
  Six different stent types were placed into tubes filled with contrast agent (ioversol or gadoteric acid), and nylon cylinders (8 mm diameter) bored in the central axis (2 and 4 mm) to mimic 75% and 95% stenoses were inserted into the stents inside the tubes. CT angiography (16- and 64-MDCT scanners using three different kernels at 120 and 140 kV) and MR angiography (1.5 T) were performed. On 2-mm coronal sections, signal intensities in the stenosed stents were compared with unstenosed segments. In addition, perceptibility of the residual lumen was assessed using a subjective score. Image analysis was performed by two experienced and blinded radiologists.
  
  
  RESULTS
  Sixteen-slice CT angiography showed relative in-stent signal intensities of 72-87%, whereas 64-MDCT angiography showed relative in-stent signal intensities of 63-99%. Sixty-four-slice CT angiography showed nearly no difference between 75% and 95% stenoses in the subjective scores. The high-contrast kernel was superior to intermediate- and low-contrast kernels. MR angiography showed relative in-stent signal intensities of 57-98%. The presence of localized artifacts and resulting inhomogeneous luminal signal caused lower subjective perceptibility ratings than the objective score would suggest.
  
  
  CONCLUSIONS
  CT angiography was superior in the differentiation between 95% stenoses and occlusions. 64-MDCT angiography was superior to 16-MDCT (mean +/- SD, 83.0 +/- 2.9 vs 78.3 +/- 3.3; p = 0.006), especially with high-contrast kernels (89.7 +/- 2.1 vs 78.3 +/- 3.3; p = 0.001). For detection of 75% stenoses, MR angiography seems to be suitable subjectively, even though no statistical significance was found.
authors.affiliation: Department of Cardiovascular and Interventional Radiology, Medical University Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria. Melanie.schernthaner@meduniwien.ac.at
authors.forename: Melanie B
authors.initials: MB
authors.lastname: Schernthaner
authors.forename: Gundula
authors.initials: G
authors.lastname: Edelhauser
authors.forename: Dominik
authors.initials: D
authors.lastname: Berzaczy
authors.forename: Ruediger
authors.initials: R
authors.lastname: Schernthaner
authors.forename: Florian
authors.initials: F
authors.lastname: Wolf
authors.forename: Johannes
authors.initials: J
authors.lastname: Lammer
authors.forename: Martin A
authors.initials: MA
authors.lastname: Funovics
mesh_terms: D001807:Blood Vessel Prosthesis / Q000009:adverse effects*; D019544:Equipment Failure Analysis; D006083:Graft Occlusion, Vascular / Q000000981:diagnostic imaging*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D019047:Phantoms, Imaging; D011474:Prosthesis Design; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015607:Stents / Q000009:adverse effects*; D014057:Tomography, X-Ray Computed / Q000379:methods*