Robust visual tracking of multiple surgical instruments for laparoscopic surgery

Abstract

In order to use pre-operative images during an intervention for navigation, they must be registered to the patient's co-ordinate system in the operating theatre or to an intra-operative image. For the registration to be valid in the case of patient movements, the registration must be updated or the patient movement must be tracked. One problem in this area is the registration of intra-operatively acquired X-ray fluoroscopies with 3D CT images obtained before the intervention as well as motion tracking for this setup. The result can be used to support the placement of pedicle screws in spine surgery or aortic endoprostheses in transfemoral endovascular aneurysm management (TEAM). The different approaches to 2D/3D registration are discussed and a novel voxel-based method is presented: using a small part of the CT image covering only the vertebra of interest, pseudo-projections are computed and the resulting vertebra template is compared to the X-ray projection using a new similarity measure which is called pattern intensity. Application, performance and registration accuracy are discussed and demonstrated by application to images of a TEAM procedure and of a spine phantom.