Abstract 20211: Contrast Improvement of Biodegradable Stents for X-ray Computed Tomography Visualization

Abstract

Introduction: Biodegradable stents present challenges during percutaneous coronary intervention (PCI) because they are typically radiolucent. For the same reason they cannot be visualized in vivo with clinical CT. By impregnating a contrast agent in the stents’ polymer coating, the stents can be seen during PCI and their degradation can be tracked in vivo using serial CT imaging. We evaluated the degradation of a polymer coated magnesium (Mg) stent in a bioreactor using dual energy microCT. Methods: Bare Mg stents with 125 μm strut thickness were coated with either a mixture of poly(lactic-co-glycolic acid) (PLGA) and triiodobenzoic acid (TIBA) or PLGA and iodinated dendrimer (ID), deployed in latex tubing, and imaged using high resolution microCT (eXplore CT120, GE) at both 80kVp and 120kVp. Stents were exposed to physiological flow in a bioreactor for 5 days, removed and dual energy microCT was repeated using same protocol. Dual energy images were processed using a custom Matlab algorithm, and the iodinated polymer was digitally segmented from the Mg struts. Results: Images of stents at baseline coated with both PLGA-ID and PLGA-TIBA showed a marked increase in CT attenuation. Images of degraded stents coated with PLGA-TIBA showed a loss of attenuation in the polymer coating but little degradation, which suggests the small TIBA molecules was not retained in the polymer. Using dual energy CT enabled segmentation of the struts and polymers. Conclusions: We have demonstrated that the radio-opacity of polymer-coated biodegradable stents can be improved with the addition of an X-ray contrast agent during the process of polymer coating with microCT. The results suggest that the degradation of biodegradable stents could be tracked in vivo. This approach could help with stent deployment and determine when the standard dual anti-platelet therapy can be stopped based on degradation as assessed with dual energy CT.