Chapter 2 Ultrasound-Based Guidance and Therapy

Minimally invasive and non-invasive image guided therapy can reduce surgical traumas and improve outcome for patients suffering from a wide variety of diseases. It may also reduce hospital stays and costs. Ultrasound is an important intraoperative imaging modality for guidance and monitoring of these therapeutic methods. Ultrasound has emerged as one of the main modalities for medical imaging in healthcare, the main reason being its ability to image soft tissue, blood flow, organ function and physiology with considerably improved image quality. Furthermore, ultrasound has the unique advantages of real time imaging, equipment portability, safety, and low costs. Ultrasound is now facing a paradigm shift in technology and clinical usability over the coming 10 years. The future potential will be released through exploration in knowledge and innovation deliveries in transducer arrays, ultrasound elec‐ tronics, software beam forming, parallel imaging and compressed sensing, minimum diffrac‐ tive wave imaging, model powered acquisition and new technology for a wide range of methods related to physiology, tissue properties and organ function in real time and on site. High-frequency ultrasound imaging makes it possible to obtain significantly improved spatial resolution, however, with limitations related to how deep into the tissue the imaging can be performed. In many image-guided surgery and therapy applications, ultrasound is performed with probes placed directly on the tissue and organ of interest (e.g. intravascular ultrasound, open chest cardiac surgery, esophagus probes for cardiac imaging, probes dedicated to surgery of pituitary gland). These applications limit the size of the ultrasound probe head and thus also the quality of the images. However, with miniaturization based on nanomaterials and