Real-Time 3-D Shape Instantiation From Single Fluoroscopy Projection for Fenestrated Stent Graft Deployment

Abstract

Robot-assisted deployment of fenestrated stent grafts in fenestrated endovascular aortic repair (FEVAR) requires accurate geometrical alignment. Currently, this process is guided by two-dimensional (2-D) fluoroscopy, which is insufficiently informative and error prone. In this letter, a real-time framework is proposed to instantiate the 3-D shape of a fenestrated stent graft by utilizing only a single low-dose 2-D fluoroscopic image. First, markers were placed on the fenestrated stent graft. Second, the 3-D pose of each stent segment was instantiated by the robust perspective-n-point method. Third, the 3-D shape of the whole stent graft was instantiated via graft gap interpolation. Focal UNet was proposed to segment the markers from 2-D fluoroscopic images to achieve semiautomatic marker detection. The proposed framework was validated on five patient-specific 3-D printed aortic aneurysm phantoms and three stent grafts with new marker placements, showing an average distance error of 1-3 mm and an average angular error of 4°. Shape instantiation codes are available online.