Percutaneous focal tumour ablation assisted by mini-stereotactic frame: proof-of-concept

The success of percutaneous focal tumour ablation largely depends on precise needle placement: an abla- tion zone, typically described as an ellipsoid centred on the ablation active needle tip, needs to completely enclose the tumour with a positive margin [1]. To facilitate precise needle placement, many types of needle guidance devices were developed, providing mechanical support and improving the targeting of the lesion [2]. Designs of these guiding apparatuses vary, including those that are rigidly attached to the Ultrasound (US) probe, enforcing the “in-plane” needle insertion. This type of targeting device forcefully maintains the needle within the US plane with the potential to improve the targeting accuracy, but at the same time, limits the entry angles of the needle and US probe placement. Other designs include mechanical and robotic (i.e., with electronic characteristics) guiders, which are large and need to be attached/positioned close to the surgical table, potentially restricting the range of movement of the healthcare providers (i.e., physicians and nurses) [3]. In this paper, we present a proof-of-principle surgi- cal navigation system based on a disposable mini- stereotactic frame, which provides mechanical support for precise needle guidance. The pose of this stereotactic needle guider is magnetically tracked and calibrated, allowing the surgeon to visualize the potential needle trajectory in a 3D Virtual Reality (VR) environment prior to needle insertion.