In vitro evaluation of second-generation drug-eluting coronary stents with 256-slice computed tomography

Background: Multi-slice computed tomography (MSCT) with improved resolution has been used for detecting coronary artery disease as an alternative to invasive coronary angiography. Since MSCT has the advantage of low cost and its non-invasiveness, assessment of coronary in-stent restenosis (ISR) with MSCT is clinically useful. Purpose: We evaluated the difference of stent lumen visibility and lumen attenuation in various stents using coronary phantoms on MSCT. Methods: Six different types of drug-eluting stent with a diameter 3.0mm (Xience V/Promus and Xience Prime [cobalt-chromium], Endeavor and Resolute Integrity [cobalt-nickel], Promus Element [platinum-chromium], Nobori [stainless steel]) were examined. The stents were placed on a diluted iodine-filled (370HU) plastic tube. Those phantoms in water-filled tank were scanned on 256-MSCT (Phillips Corporation). Multi-planar reformation (MPR) images of each stent were reconstructed and profile curves were obtained by MPR images. As an index of stent lumen, the full width at half maximum (FWHM) was calculated using profile curve. We assessed the stent lumen visually by the normalized-rank approach and physically using profile curves. Results: The least degree of visualization was found in the Promus Element stent (p<0.05). Profile curves showed both peak CT value (stent strut) and valley CT value (stent lumen) were highest in the Promus Element stent (2,327HU and 713HU, respectively) (Figure 1). In the FWHM, the Promus Element stent was 0.96 mm at the minimum and the Xience V/Promus stent was 1.40 mm at the maximum. Figure 1 Conclusions: Stent lumen visibility largely varies depending on the stent type of the material and design. These data suggest that the platinum alloy stent is unsuitable in the examination of coronary stents for ISR using MSCT.