Multimodal Data Fusion and Registration for Needle Guidance in Percutaneous Procedures

Minimally invasive procedures, such as the percutaneous procedures, present more difficulties than the open approaches due to the limited access to the patient, the limited field of view and the difficult manipulation of the instruments. Navigation systems could help overcome these difficulties by providing additional information to the surgeon or the interventional radiologists during the procedure. In particular they can provide the exact localization of the instruments inside the patients body in relation to the tumor margins and risk structures. This work presents a method to track, register and integrate pre-operative images, with multimodal data acquired during the actual intervention, in a navigation system for percutaneous procedures. The goal of the navigation system is the virtual reconstruction of the operative scenario by the fusion of different images in the same reference system and the exact localization and tracking of the instruments used during the intervention, such as the ultrasound (US) probe and the needle. The proposed method focuses on the assistance of percutaneous cryoablation of renal tumors because this procedure requires the surgeon to translate the mental plan developed on the computer tomography (CT) images, acquired before the intervention, into the reality without any hint about internal structures position or only with the assistance of a 2D US image [1]. The success of a percutaneous intervention is bound to the precision of the needle insertion along the planned trajectory. Together with the registration and fusion of different image datasets, the needle used to accomplish the procedure is calibrated in the same reference system and is represented in the virtual environment. The use of virtual reconstruction increases the awareness of the on going procedure, by providing a rendering of the different tools and structures involved in the intervention and improves the positioning of the needle to be inserted