title: Evaluation of coronary stents in vitro with CT angiography: effect of stent diameter, convolution kernel, and vessel orientation to the z-axis.
abstract: BACKGROUND
  The aims of the present study were to assess the effect of the stent diameter, convolution kernel, and vessel orientation to the z-axis on the evaluation of coronary stents, in vitro with computed tomography (CT) angiography.
  
  
  RESULTS
  Seven vascular models (2 models without stenosis, 2 with obstruction, and 3 with stenosis) with an approximate inner diameter of 3 or 4 mm, filled with contrast material (79 or 330 HU) were scanned with a 16-detector CT. The diameter measurement of the stent lumen and stenosis evaluation were both done in an orientation parallel to the z-axis of the scanner using 4 convolution kernels. The measured diameters of the stented lumen were 47-57% and 36-45% smaller than the actual inner diameter of the 3- and 4-mm diameter models, respectively. The diameter measurement of the stent lumen and visualization of the in-stent stenosis were improved by using convolution kernels with higher spatial resolution. The in-stent artifacts were evaluated in 4 orientations (0 degrees , 30 degrees , 60 degrees , 90 degrees ) to the z-axis. The artifact was the minimum in 0 degrees to the z-axis, and the maximum in 90 degrees .
  
  
  CONCLUSIONS
  Visualization of the lumen of a stent by CT is affected by its diameter, convolution kernel, and vessel orientation to the z-axis, and these factors should be taken into consideration in the stent evaluation.
authors.affiliation: Department of Radiology, Teikyo University School of Medicine, Tokyo, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Suzuki
authors.forename: Shigeru
authors.initials: S
authors.lastname: Furui
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Kaminaga
authors.forename: Teiyu
authors.initials: T
authors.lastname: Yamauchi
authors.forename: Sadatoshi
authors.initials: S
authors.lastname: Kuwahara
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Yokoyama
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Suzuki
authors.forename: Takaaki
authors.initials: T
authors.lastname: Isshiki
mesh_terms: D000792:Angiography; D005069:Evaluation Studies as Topic; D006083:Graft Occlusion, Vascular / Q000000981:diagnostic imaging*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008955:Models, Cardiovascular; D012107:Research Design; D015607:Stents; D036542:Tomography, Spiral Computed / Q000379:methods