High intensity focused ultrasound (HIFU) or focused ultrasound surgery (FUS) is a completely noninvasive treatment modality. It has long been known to oer “trackless lesioning,” and it has been identied as an “ideal surgical tool” for several decades. However, only aer it was integrated with modern imaging methods has HIFU become a clinical reality. A high quality imaging technique was needed to provide visualization and localization of target tissue, monitoring of tissue changes during treatment, and outcome assessment aer treatment.