HIFU (high intensity focused ultrasound) (sometimes FUS or HIFUS) is a highly precise medical procedure using high-intensity focused ultrasound to heat and destroy pathogenic tissue rapidly. It is one modality of therapeutic ultrasound, and although it induces hyperthermia it should not be confused with this technique which heats much less rapidly and to much lower therapeutic temperatures (generally < 45°C).
Therapeutic ultrasound is a minimally invasive or non-invasive method to deposit acoustic energy into tissue. Applications include tissue ablation (HIFU) (for tumor treatments, for example). Hyperthermia treatments (low-level heating combined with radiation or chemotherapy), or the activation or enhanced delivery of drugs are unrelated to HIFU.