X-ray micro-tomography of a coronary stent deployed in a model artery

Coronary stents are small scaffolds routinely implanted during angioplasty procedures to re-open coronary arteries which have become narrowed by an atherosclerotic plaque. Despite the advent of drug-eluting stents to reduce restenosis (re-narrowing) after the procedure, complications still arise and mechanical factors may be partly the cause. Stents are being used in increasingly complex cases, so new forms of pre-clinical testing may be helpful in evaluating stent designs and deployment techniques. With this in mind, an in vitro experiment was conducted to evaluate the use of X-ray micro-tomography to image stents at various stages of deployment. A stent was deployed in an artificial artery while using a synchrotron X-ray source to obtain the tomography scans. A volume element (voxel) size of 5.3 microm was achieved, with a vertical field of view of 4.5mm. The imaging of the stent and artificial artery materials was better than expected, despite some attenuation artifacts and the high monochromatic beam energy used (25 keV). Experimental problems are discussed, together with recommendations for improving the technique. It is intended that this technique will be of interest to engineers and clinicians as a pre-clinical test.