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Augmented Reality for Reducing Intraoperative Radiation Exposure to Patients and Clinicians during X-Ray Guided Procedures
Published in Terry M. Peters, Cristian A. Linte, Ziv Yaniv, Jacqueline Williams, Mixed and Augmented Reality in Medicine, 2018
Nicolas Loy Rodas, Nicolas Padoy
Several minimally invasive procedures rely on percutaneous access to inner organs or other tissue, which is generally performed using ultrasound or x-ray imaging for accurately guiding a needle to a target. In the latter case, patient and staff are exposed to a certain amount of radiation depending on the time it takes to reach the target. Such an exposure is higher when fluoroscopy (continuous x-ray imaging) is used to acquire real-time feedback of the needle’s trajectory, and, especially in complex procedures, can lead to radiation-induced skin injuries to the patient (Kirkwood et al. 2014). As an alternative, several works have proposed using AR to provide an enhanced visualization of a patient’s inner anatomical structures. For instance, Müller et al. (2013) and Seitel et al. (2016) propose to use AR to facilitate the navigation during percutaneous needle insertion and therefore reduce the amount of performed x-ray acquisitions. These approaches rely on the registration of a preoperative patient’s model (CT) to the user’s viewpoint, which is achieved either by means of fiducial markers (Müller et al. 2013) or by using the depth data from an Red, Green, Blue-Depth (RGB-D) camera and surface matching algorithms (Seitel et al. 2016). Information such as the insertion trajectory or the target’s position can be overlaid onto a video stream serving as guidance visualization during the needle insertion. Similarly, x-ray guidance is crucial during orthopedic and trauma surgery to guide joint replacements, or for the treatment of fractures. To facilitate guidance during such procedures, Navab et al. (2010) propose augmenting a mobile angiographic C-arm with a video camera and mirror construction, as this enables a direct overlay of the x-ray images over the video stream. After a calibration procedure, such a design enables both the camera and the x-ray source centers to be virtually aligned, and therefore to provide an AR visualization of the x-ray images over the video stream. Studies have reported that such an intuitive intraoperative overlay allows surgeons to reduce the number of x-ray acquisitions performed and thereby radiation exposure for several clinical tasks, such as skin incision, entry point localization, and x-ray positioning (Chen et al. 2013).
Catheter-based closure of aortic and mitral paravalvular leaks: existing techniques and new frontiers
Published in Expert Review of Medical Devices, 2018
Timothy A. Joseph, Colleen E. Lane, Erin A. Fender, Chad J. Zack, Charanjit S. Rihal
Significant PVL complicates between 1% and 5% of valve replacements and the incidence is highest among patients with mechanical mitral valve replacement. Symptoms include congestive heart failure and hemolysis. Multimodality imaging including both transesophageal echocardiography and cardiac CT are critical in establishing the diagnosis and defining the size, location, and mechanism of PVL. Surgery is appropriate for patients with PVL due to endocarditis or valve dehiscence. Increasingly, percutaneous treatment is the first-line treatment for many cases of PVL. Percutaneous interventions are associated with less morbidity and mortality when compared to reoperation. However, persistent leak, hemolysis, device embolization, and disc impingement continue to present significant challenges, in large part because currently used devices are not designed for PVL closure. The creation of dedicated devices for leak closure is needed to improve procedural success rates.