title: Assessment of coronary stent in vitro on multislice computed tomography angiography: improved in-stent visibility by the use of 140-kV tube voltage.
abstract: OBJECTIVE
  To assess the effect of tube voltage on the in-stent visibility of coronary stents in vitro on computed tomography (CT) angiography.
  
  
  METHODS
  A total of 6 vascular models (3 models without stenosis and 3 with stenosis) using 3 kinds of stent (Bx Velocity, Express2, and Driver) with an inner diameter of approximately 3.5 mm and filled with contrast material (CT attenuation, 450 Hounsfield units) were scanned by means of a 16-detector row CT. We assessed the visual stenosis evaluation and inhomogeneity of stent lumen in 4 orientations (0-, 30-, 60-, and 90-degree angles) relative to the z-axis of the scanner using 3 imaging techniques (120-kV tube voltage using a medium convolution kernel, 120-kV tube voltage using a convolution kernel for bone, and 140-kV tube voltage using a convolution kernel for bone). Statistical analysis involved F test with a statistical significance of P < 0.05.
  
  
  RESULTS
  The convolution kernel for bone made it easier to evaluate the stenosis inside the stents, although it increased the luminal inhomogeneity significantly (Bx Velocity and Express2, P < 0.005; Driver, P < 0.05). The luminal inhomogeneity tended to increase as the strut diameter and the weight per unit length increased. Using 120-kV tube voltage, the luminal inhomogeneity inside the stents was at the minimum in the angle of 0 degree relative to the z-axis, and at the maximum in the angle of 90 degrees, except for Driver. The 140-kV tube voltage was effective for the improvement of luminal inhomogeneity and visibility of in-stent stenosis compared with the 120-kV tube voltage.
  
  
  CONCLUSIONS
  The in-stent visibility of coronary stents on CT angiography can be improved by the use of 140-kV tube voltage with the convolution kernel for bone.
authors.affiliation: Department of Radiology, Teikyo University School of Medicine, Itabashi-ku, Tokyo, Japan. s-suzuki@med.teikyo-u.ac.jp
authors.forename: Shigeru
authors.initials: S
authors.lastname: Suzuki
authors.forename: Shigeru
authors.initials: S
authors.lastname: Furui
authors.forename: Sadatoshi
authors.initials: S
authors.lastname: Kuwahara
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Kaminaga
authors.forename: Teiyu
authors.initials: T
authors.lastname: Yamauchi
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Kawasaki
authors.forename: Kumiko
authors.initials: K
authors.lastname: Konno
authors.forename: Ken
authors.initials: K
authors.lastname: Kozuma
authors.forename: Takaaki
authors.initials: T
authors.lastname: Isshiki
mesh_terms: D016477:Artifacts; D003287:Contrast Media; D017023:Coronary Angiography / Q000295:instrumentation*; D023921:Coronary Stenosis / Q000000981:diagnostic imaging* / Q000628:therapy*; D004867:Equipment Design; D006801:Humans; D008955:Models, Cardiovascular; D019047:Phantoms, Imaging; D011857:Radiographic Image Interpretation, Computer-Assisted; D015607:Stents; D015898:Tomography Scanners, X-Ray Computed
chemical_list: D003287:Contrast Media