New frontiers in research of real-time imaging during endovascular minimally invasive surgery are focusing attention on studies for direct vision of the inner vessel wall, helping catheter tracking and guidance. This master thesis belongs to a European research project, called SCATh (Smart Catheterization), whose primary objective is the creation of an innovative ICT platform for training, pre-operative planning and computer-aided surgical interventions, that closes the existing gap between the reality of the catheter inside the cardiovascular system and the manner in which this reality is presented and made accessible to the interventionalist. The goal of this master thesis is to design and develop a catheter-based optical imaging system that enables intracardiac and intravascular visualization in real time through blood.
There are lots of methodologies of cardiovascular imaging which are used to capture detailed real-time information during catheter-based diagnosis and interventions. Advanced techniques in angiography based on X-rays -fluoroscopy- and computed tomography and devices based on ultrasound are typical examples of imaging system for the visualization of blood vessel obtaining also high resolution images.
New strategies to have a direct vision through blood would be a disruptive innovation. In fact this catheter-based vision system has the advantage of non ionizing radiation utilization, non total occlusion of vessel and non temporary remotion of blood (opaque in the visible light) from the vision system eld of view. Thus far there are no commercial devices for a direct vision and only two patents deal in vision system with indium gallium arsenide technology and light with wavelengths longer than 1500nm. A drawback to these radiations is the local temperature increase, which provokes hemolysis. We built a prototype of an infrared angioscope for local environment scanning on the catheter tip and for direct vision of inner vessel surface, working with wavelengths where the blood attenuation is minimum and the hemolysis is reduced.
In Chapter 1, after a description of the state of art of cardiovascular imaging system technologies, the optical blood properties are analyzed because they affect the image quality. Interaction between blood and electromagnetic spectrum highlights the increasing interest in near infrared angioscopy methodology. In fact
moving from the visible region to the infrared one, blood is more transparent and a direct vision through blood is feasible. State of the NIR angioscopes is reported.
Chapter 2 presents the design of the infrared vision system, which is made of three main parts: illumination, camera and optics. The lighting source is a custom system which uses LED devices in the 800-1000nm range. Because of the wavelenghts range, a CMOS sensor is suitable for the application and the commercial camera Medigus Introspicio 120 is used. The optical surfaces are
developed with the collaboration of the Centro Ricerca Plast-Optica and supported with optical simulations (ASAP optical software). The final system has two visual view fields, allowing the left and right sight of the blood vessel. Each sector has eld of view of 130° horizontal 70° vertical.
In Chapter 3 the mechanical design for the integration of all components is developed, obtaining the final structure, which has a cylinder-shape of 8.4mm diameter and 30.0mm height. The system is placed on tip of catheter, which has been developed for insertion inside the vascular system.
Chapter 4 reports tests conducted to assess vision system functioning. The first test assesses the penetration distance in air. Subsequently the performances of the system are evaluated when it is dipped into an absorbing medium. Tests have been done in tomato juice and in blood.
In Chapter 5 the final conclusions of the development of a near infrared angioscope prototype for endovasculat application are treate
