Tobias Gassenmaier MD, Presenter: Nothing to Disclose

Nils Petri, Abstract Co-Author: Nothing to Disclose

Thomas Allmendinger, Abstract Co-Author: Employee, Siemens AG

Thomas G. Flohr PhD, Abstract Co-Author: Employee, Siemens AG

David Christian Maintz MD, Abstract Co-Author: Nothing to Disclose

Wolfram Voelker MD, Abstract Co-Author: Nothing to Disclose

Thorsten Alexander Bley MD, Abstract Co-Author: Nothing to Disclose

To evaluate in-stent lumen visibility of 27 modern and commonly used coronary stents (16 individual stent types, two stents at six different sizes each) utilizing a third-generation dual-source CT scanner.

All stents were implanted in a plastic tube filled with contrast medium diluted to a density of 350 HU. The tube was placed in a plastic box filled with an emulsion of sunflower oil and contrast adjusted to a density of -70 HU to simulate the attenuation of epicardial fat. Scans were performed in an orientation parallel to the scanner’s z-axis for all stents (i.e. 0°) and additionally in an orientation of 90° for stents expanded to a diameter of 3.0 mm. Two stents were evaluated in all available diameters (2.25 mm to 4.0 mm) to determine the influence of stent diameter on stent lumen visibility. Scans were acquired in a retrospectively ECG-gated cardiac spiral dual-source mode with a collimation of 96x0.6 mm, tube voltage of 120 kVp with 340 mAs tube current. Evaluation was performed using a medium-soft (Bv40), a medium-sharp (Bv49) and a sharp (Bv59) convolution kernel optimized for vascular imaging. Axial reformations of all stents were used for evaluation using a window width of 1500 HU and a center of 300 HU.

Mean visible stent lumen of stents with 3.0 mm diameter ranged from 53.3% (IQR 48.9 - 56.7%) to 73.9% (66.7 - 76.7%) depending on the kernel applied at 0°, and was highest at an orientation of 90° with 80.0% (75.6 - 82.8%) using the Bv59 kernel, strength 4. Differences between all kernels were significant with p ≤ 0.002. Orientation of the stent towards the gantry had a significant effect regarding both visible stent lumen diameter and in-stent attenuation (p ≤ 0.004). Visible stent lumen declined with decreasing stent size (p < 0.001), ranging from 50% / 53% to 76% / 76% in the two stents evaluated in sizes from 2.25 mm to 4.0 mm, using the Bv59 kernel, strength 4.

Use of third generation dual-source CT scanners enables stent lumen visibility of up to 80% in metal stents and 100% in bioresorbable stents in this in vitro setting. It may therefore be a valid method for detecting in-stent restenosis.

Improved in-vitro stent lumen visibility of third generation dual-source CT scanners may allow a sufficient non-invasive method to detect or exclude in-stent restenosis in vivo.

Gassenmaier, T, Petri, N, Allmendinger, T, Flohr, T, Maintz, D, Voelker, W, Bley, T, Next Generation Coronary CT Angiography: In vitro Evaluation of 27 Coronary Stents.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14006792.html