In the current clinical workflow of endovascular abdominal aortic repairs (EVAR) a stent graft is inserted into the aneurysmatic aorta under 2D angiographic imaging. Due to the missing depth information in the X-ray visualization, it is highly difficult in particular for junior physicians to place the stent graft in the preoperatively defined position within the aorta. Therefore, advanced 3D visualization of stent grafts is highly required. In this paper, we present a novel algorithm to automatically match a 3D model of the stent graft to an intraoperative 2D image showing the device. By automatic preprocessing and a globalto-local registration approach, we are able to abandon user interaction and still meet the desired robustness. The complexity of our registration scheme is reduced by a semi-simultaneous optimization strategy incorporating constraints that correspond to the geometric model of the stent graft. Via experiments on synthetic, phantom, and real interventional data, we are able to show that the presented method matches the stent graft model to the 2D image data with good accuracy.

Common carotid intimaÀmedia thickness (CIMT) is a commonly used marker for atherosclerosis and is often computed in carotid ultrasound images. An analysis of different computerized techniques for CIMT measurement and their clinical impacts on the same patient data set is lacking. Here we compared and assessed five computerized CIMT algorithms against three expert analysts' manual measurements on a data set of 1088 patients from two centers. Inter-and intra-observer variability was assessed, and the computerized CIMT values were compared with those manually obtained. The CIMT measurements were used to assess the correlation with clinical parameters, cardiovascular event prediction through a generalized linear model and the KaplanÀMeier hazard ratio. CIMT measurements obtained with a skilled analyst's segmentation and the computerized segmentation were comparable in statistical analyses, suggesting they can be used interchangeably for CIMT quantification and clinical outcome investigation. To facilitate future studies, the entire data set used is made publicly

Minimally invasive treatment of vascular disease demands dynamic navigation through complex blood vessel pathways and accurate placement of an interventional device, which has resulted in increased reliance on fluoroscopic guidance and commensurate radiation exposure to the patient and staff. Here we introduce a guidance system inspired by electric fish that incorporates measurements from a newly designed electrogenic sensory catheter with preoperative imaging to provide continuous feedback to guide vascular procedures without additional contrast injection, radiation, image registration, or external tracking. Electrodes near the catheter tip simultaneously create a weak electric field and measure the impedance, which changes with the internal geometry of the vessel as the catheter advances through the vasculature. the impedance time series is then mapped to a preoperative vessel model to determine the relative position of the catheter within the vessel tree. We present navigation in a synthetic vessel tree based on our mapping technique. experiments in a porcine model demonstrated the sensor's ability to detect cross-sectional area variation in vivo. these initial results demonstrate the capability and potential of this novel bioimpedance-based navigation technology as a non-fluoroscopic technique to augment existing imaging methods. clinical Motivation The number of vascular procedures performed under fluoroscopic guidance is increasing as minimally invasive techniques are developed for the diagnosis and treatment of a widening array of vascular diseases 1,2. With the reliance on fluoroscopic imaging for device guidance and navigation comes increased radiation dose to the patient 3 and interventional staff 4-6. Furthermore, these complicated endovascular procedures require dynamic navigation and accurate positioning of interventional devices relative to the vascular tree, which can be extremely challenging with only two-dimensional fluoroscopic images (see Supplementary Material for example case). As a result, multiple contrast agent injections, image acquisitions, and catheter exchanges are often necessary. There are existing techniques to reduce radiation use during endovascular procedures. Systems such as CARTO 3 (Biosense Webster, Diamond Bar, CA) and Rhythmia (Boston Scientific, Marlborough, MA) employ external electromagnetic or external electric sources on the outside of the body to localize catheters in the cardiac chamber. These technologies have revolutionized electroanatomic mapping of the heart and reduced radiation exposure during cardiac electrophysiology procedures 7-10 but are currently unsuitable for catheter navigation through the vessel tree. In fact, the catheters are usually navigated from the femoral artery using fluoroscopic guidance, because the sensing volume created by the external sources is limited. The accuracy of the position estimate is greatly diminished in the presence of patient movement, vessel deformation, and unstable heartbeats 11,12. Additionally, these techniques require s...