Reduction of metal artifacts in X-ray computed tomography. Application to vascular imaging in the presence of stents

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Blood vessel occlusion - due to atherosclerosis or other causes - is an important health problem for which stent placement is a widespread treatment procedure. Follow-up of the patients is required in order to evaluate and detect in-stent restenosis caused by thrombus formation or neointimal hyperplasia. Therefore, there is a strong need for precise and nearly noninvasive techniques for assessing the lumen cross-section inside the stent. Unfortunately, most commonly available imaging modalities, including X-ray computed tomography (CT) and magnetic resonance imaging, yield poor  and unreliable results due to the strong metal artifacts induced by the stent. The goal of the project is to develop and validate X-ray CT image reconstruction techniques that present significant reduction of metal artifacts, with applications to vascular imaging and restenosis assessment after stent placement. The project will be carried out in four stages: - Enhancement of realistic vascular phantoms, so as to offer the possibility of inserting various types of stents and of modeling various degrees of restenosis. - Development and validation of an initial 2D X-ray CT, that will be based on an accurate model of the phenomena causing X-ray artifacts, and that will be able to reconstruct images of realistic size (512x512 pixels) reasonably fast. - 3D extension and validation of the method by developing efficient numerical techniques and by taking advantage of the special structure of the reconstruction problem. - Clinical feasibility study, that will constitute the initial stage of the dissemination and translation of the methods developed in-the course of the project.