An Augmented Reality Approach for Initializing 2D/3D Registration

Abstract

We describe a technique for intraoperative initialization of 2D/3D registration. The technique uses a tracked tool that is already available in the operating room, as part of an image-guided navigation system, to establish the transformation between the preoperative volume and the intraoperative patient. Initialization is performed in two phases: volume-tool pose planning in the virtual world, and patient-tool pose mimicking in the physical world. Depending on the requirements for accuracy and interaction time, the second phase can be done using either instant, coarse, initialization or Augmented Reality (AR) based interactive initialization. The former method is fast and requires no intraoperative modalities, while the latter uses intraoperative x-rays as a guide to continuously refine the initialization. The proposed technique is appropriate for intraoperative 2D/3D initialization as it is contactless, fast, and uses devices already available as part of the navigation system. Evaluation was done using three publicly available reference data sets. The instant, coarse, initialization was able to provide a mean Target Registration Error (mTRE) of 28-40mm, with the majority of the error associated with errors in translation. The AR-based initialization was able to achieve a mTRE on the order of 5-10mm with an average interaction time of 40-60sec.