Augmented Reality as a Tool to Guide Patient-Specific Templates Placement in Pelvic Resections.

Patient-specific templates (PST) have become a useful tool for guiding osteotomy in complex surgical scenarios such as pelvic resections. The design of the surgical template results in sharper, less jagged resection margins than freehand cuts. However, their correct placement can become difficult in some anatomical regions and cannot be verified during surgery. Conventionally, pelvic resections are performed using Computer Assisted Surgery (CAS), and in recent years Augmented Reality (AR) has been proposed in the literature as an additional tool to support PST placement. This work presents an AR task to simplify and improve the accuracy of the positioning of the template by displaying virtual content. The focus of the work is the creation of the virtual guides displayed during the AR task. The system was validated on a patient-specific phantom designed to provide a realistic setup. Encouraging results have been achieved. The use of the AR simplifies the surgical task and optimizes the correct positioning of the cutting template: an average error of 2.19 mm has been obtained, lower than obtained with state-of-the-art solutions. In addition, supporting PST placement through AR guidance is less time-consuming than the standard procedure that solely relies on anatomical landmarks as reference.

Single feature constrained manual registration method for Augmented Reality applications in gynecological laparoscopic interventions.

Augmented Reality (AR) can avoid some of the drawbacks of Minimally Invasive Surgery and may provide opportunities for developing innovative tools to assist surgeons. In laparoscopic surgery, the achievement of easy and sufficiently accurate registration is an open challenge. This is particularly true in procedures, such as laparoscopic abdominal Sacro-Colpopexy, where there is a lack of a sufficient number of visible anatomical landmarks to be used as a reference for registration. In an attempt to address the above limitations, we developed and preliminarily testes a constrained manual procedure based on the identification of a single anatomical landmark in the laparoscopic images, and the intraoperative measurement of the laparoscope orientation. Tests in a rigid in-vitro environment show good accuracy (median error 2.4 mm obtained in about 4 min) and good preliminary feedback from the technical staff who tested the system. Further experimentation in a more realistic environment is needed to validate these positive results. Clinical Relevance - This paper provides a new registration method for the development of AR educational videos and AR-based navigation systems for laparoscopic interventions.

A Rendering Engine for Integral Imaging in Augmented Reality Guided Surgery.

In the field of image-guided surgery, Augmented Reality wearable displays are a widely studied and documented technology for their ability to provide egocentric vision together with the overlap between real and virtual content. In particular, optical see-through (OST) displays have the advantage of maintaining visual perception of the real world. However, OST displays suffer from vergeance-accomodation conflict when virtual content is superimposed on real world. Furthermore, the calibration methods required to achieve geometric consistency between real and virtual are inherently error-prone. One of the solutions, already studied, to these problems is to use of integral imaging displays. In this paper we present an easy and straightforward real-time rendering strategy implemented in modern OpenGL to show the 3D image of a virtual object on a wearable OST display deploying the integral imaging approach. Clinical Relevance- The algorithm proposed open the way towards more effective AR surgical navigation in terms of comfort of the AR experience and accuracy of the AR guidance.

Augmented reality system for freehand guide of magnetic endovascular devices.

Magnetic guide of endovascular devices or magnetized therapeutic microparticles to the specific target in the arterial tree is increasingly studied, since it could improve treatment efficacy and reduce side effects. Most proposed systems use external permanent magnets attached to robotic manipulators or magnetic resonance imaging (MRI) systems to guide internal carriers to the region of treatment. We aim to simplify this type of procedures, avoiding or reducing the need of robotic arms and MRI systems in the surgical scenario. On account of this we investigated the use of a wearable stereoscopic video see-through augmented reality system to show the hidden vessel to the surgeon; in this way, the surgeon is able to freely move the external magnet, following the showed path, to lead the endovascular magnetic device towards the desired position. In this preliminary study, we investigated the feasibility of such an approach trying to guide a magnetic capsule inside a vascular mannequin. The high rate of success and the positive evaluation provided by the operators represent a good starting point for further developments of the system.