Electromagnetic navigation system for endovascular surgery & new strategies for innovative medical devices testing

This thesis deals with two different but closely related issues: the study and development of an image guidance system for endovascular surgery and the definition of new strategies for innovative medical devices testing. More particularly, this work describes how to develop an electromagnetic navigator to aid the execution of endovascular procedures and to overcome drawbacks related to the fluoroscopic guidance modality, such as: loss of depth perception and spatial orientation (traditional C-Arms in fact provide bidimensional images); radiation exposure to staff and patient; adverse effects of contrast medium (administered for vessels visualization). Moreover an innovative methodology for the fabrication of realistic simulation environments is presented. The navigator assessment has in fact required the development of a testing environment compatible with fluoroscopy and CT imaging and able to realistically reproduce the morphology of the human vascular system. Currently available solutions on the market are in fact limited to the simulation of simplified standard models within a restricted database and thus are inadequate to reproduce technical difficulties of real endovascular procedures. For this purpose, a fabrication strategy to build an endovascular patient-specific simulator starting from the segmentation of real CT images has been developed. This procedure has been later extended to the development of silicone replicas of other anatomical structures and has been enriched with the possibility to add virtual simulation elements. This work presents the most important outcomes obtained in each of the above mentioned research areas. A detailed description of the medical and technical background is reported; then, a strategy to develop a navigator allowing the real-time visualization of endovascular tools within the 3D model of the patient anatomy with no need for live fluoroscopy and contrast medium is proposed. Five DOFs electromagnetic sensors are calibrated and used for real-time tracking of position and orientation of endovascular catheters and guidewires, while Intraoperative 3D Rotational Angiography is used to acquire the 3D model of patient anatomy. A preliminary navigator prototype was developed to prove the feasibility of the system and to evaluate its accuracy and usefulness using an ad-hoc fabricated patient-specific simulator. A detailed description of the fabrication strategy to build such kind of anthropomorphic simulator is reported. The proposed approach allows the fabrication of a single organ, district or apparatus, according to the need. It is not limited to the abdominal region, in fact the procedure can be extended to almost any other region of the body; moreover synthetic organs can be paired with sensors and enriched with a consistent virtual scenario. The target of this kind of surgical simulators is to offer the possibility to conduct systematic pre-clinical medical assessment of innovative devices and to obtain explicit guidelines that can improve the design process. Furthermore they can be used for surgical training purpose: they can offer resident surgeons the chance to learn how to perform a surgical task or an entire procedure, and in this way gain an improved awareness of surgical methods.