Automatic patient registration for port placement in minimally invasive endoscopic surgery

An effective visualization technique for depth perception in augmented reality-based surgical navigation

BACKGROUND

Depth perception is a major issue in augmented reality (AR)-based surgical navigation. We propose an AR and virtual reality (VR) switchable visualization system with distance information, and evaluate its performance in a surgical navigation set-up.

METHODS

To improve depth perception, seamless switching from AR to VR was implemented. In addition, the minimum distance between the tip of the surgical tool and the nearest organ was provided in real time. To evaluate the proposed techniques, five physicians and 20 non-medical volunteers participated in experiments.

RESULTS

Targeting error, time taken, and numbers of collisions were measured in simulation experiments. There was a statistically significant difference between a simple AR technique and the proposed technique.

CONCLUSIONS

We confirmed that depth perception in AR could be improved by the proposed seamless switching between AR and VR, and providing an indication of the minimum distance also facilitated the surgical tasks.

Markerless Endoscopic Registration and Referencing

Accurate patient registration and referencing is a key element in navigated surgery. Unfortunately all existing methods are either invasive or very time consuming. We propose a fully non-invasive optical approach using a tracked monocular endoscope to reconstruct the surgical scene in 3D using photogrammetric methods. The 3D reconstruction can then be used for matching the pre-operative data to the intra-operative scene. In order to cope with the near real-time requirements for referencing, we use a novel, efficient 3D point management method during 3D model reconstruction. The presented prototype system provides a reconstruction accuracy of 0.1 mm and a tracking accuracy of 0.5 mm on phantom data. The ability to cope with real data is demonstrated by cadaver experiments.