Ethan Joseph Halpern MD, Presenter: Grant, Bristol-Myers Squibb Company Equipment support, Toshiba Corporation

David J. Halpern, Abstract Co-Author: Nothing to Disclose

Jeffrey Harold Yanof PhD, Abstract Co-Author: Employee, Koninklijke Philips Electronics NV

Sigal Amin-Spector, Abstract Co-Author: Employee, Koninklijke Philips Electronics NV

David Fischman, Abstract Co-Author: Nothing to Disclose

Jacob Sosna MD, Abstract Co-Author: Research grant, Koninklijke Philips Electronics NV Consultant, Carestream Health, Inc Consultant, ActiViews Ltd

CT evaluation of coronary stent restenosis is limited by blooming artifacts from high x-ray attenuating materials such as metal struts and mural calcium. The purpose of this study was to reduce blooming artifacts during in vitro evaluation of contrast-enhanced stent lumens with dual energy CT (DECT).

Three stainless steel stents - the multi-link Zeta (Guidant), the Zipper MX (Medtronic), and the Cypher (sirolimus eluting - Cordis) - and one cobalt chromium stent - the Vision (Guidant) - were scanned with a multidetector DECT (Philips Medical Systems). Stent sizes of 2.5, 3.5, and 4.0 mm diameter were deployed within appropriately sized plastic tubing filled with iodinated contrast at a density of approximately 300 HU. Stents were submerged in a water bath and scanned at 0º, 90º, and oblique to the z-axis of the scanner. The prototype DECT has a single x-ray source (set to 140 kVp); low and high energy scans were simultaneously obtained with a double-layered, 32-row detector panel. Images were reconstructed with both standard and high resolution filters. A dual-energy histogram and full width half maximum edge detection were used within a novel multi-spectral viewer (Philips Medical Systems) to access stent lumen diameter and strut thickness.

The spectral viewer was used to classify stent voxels (from adjacent contrast enhanced lumen voxels) and to highlight the stent voxels on low and high energy images of the enhanced lumen. High energy images demonstrated decreased strut thickness (20% lower, p<0.01) and larger lumen diameters (20% greater, p<0.01) as compared to low energy images. Use of a high resolution reconstruction filter resulted in a further decrease in measured strut thickness (2%) and increase in measured stent lumen (5%).

Selective classification of coronary stents and the contrast-enhanced lumen inside a stent is possible with dual energy tissue separation. Stent blooming is decreased in images obtained from the high energy components of the x-ray spectrum. A high resolution filter can further minimize blooming.

Analysis of different energy components in the CT spectrum may improve the accuracy of assessment of the coronary stent lumen.

Halpern, E, Halpern, D, Yanof, J, Amin-Spector, S, Fischman, D, Sosna, J, In Vitro Assessment of Coronary Stents Using Dual Energy CT (DECT) with a Novel Multienergy Spectral Viewer.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6005462.html