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The complete expansion of the stent during a percutaneous transluminal coronary angioplasty (PTCA) procedure is essential for treatment of a stenotic segment of a coronary artery. Inadequate expansion of the stent is a major predisposing factor to in-stent restenosis and acute thrombosis. Stents are positioned and deployed by fluoroscopic guidance. Although the current generation of stents are made of materials with some degree of radio-opacity to detect their location after deployment, proper stent expansion is hard to asses. In this work, we introduce a new method for the three-dimensional (3D) reconstruction of the coronary stents in-vivo utilizing two-dimensional projection images acquired during rotational angiography (RA). The acquisition protocol consist of a propeller rotation of the X-ray C-arm system of 180°, which ensures sufficient angular coverage for volume reconstruction. The angiographic projections were acquired at 30 frames per second resulting in 180 projections during a 7 second rotational run. The motion of the stent is estimated from the automatically tracked 2D coordinates of the markers on the balloon catheter. This information is used within a motion-compensated reconstruction algorithm. Therefore, projections from different cardiac phases and motion states can be used, resulting in improved signal-to-noise ratio of the stent. Results of 3D reconstructed coronary stents in vivo, with high spatial resolution are presented. The proposed method allows for a comprehensive and unique quantitative 3D assessment of stent expansion that rivals current X-ray and intravascular ultrasound techniques.

Implantable cardiac devices, such as stents and septal defect closure devices are sometimes difficult to see on angiographic X-ray projection images. We present a method to enhance the visibility of these devices in rotational X-ray angiography acquisitions using automated marker detection and motion compensation. Automatic marker detection allows registration of the devices in the images of the rotational run. Motion compensation is done by warping the images to a specific reference position. Averaging multiple of those motion compensated images together with the reference frame results in an enhanced image with improved visibility due to an increase in contrast of the device with the background structure. This allows the clinician to look at the device from multiple angles with an improved visibility of the device to better appreciate the 3D geometry of the device. In particular, enhancement of rotational acquisitions compared to standard enhanced fixed-angle acquisitions allows the clinician to better perceive any asymmetry in the deployed device.