 Thyroid nodules are very common worldwide. In an iodine-replete population like Hong Kong, the estimated prevalence of a clinically palpable thyroid nodule, is close to 5 while the prevalence of ultrasonically detectable nodules could be up to 67. With the frequent use of computed tomography, carotid ultrasound studies and positron emission scans nowadays, many small, non-palpable thyroid nodules are incidentally detected. The use of high intensity focused ultrasound MRI guided or ultrasound guided have been used to treat different types of soft tissue cancer like prostate cancer, liver cancer and breast cancer. This device has been tried in a clinical study where patients with thyroid nodules, who were already scheduled for thyroidectomy, were treated using HIFU in order to evaluate the safety and feasibility of the device and to better determine the treatment parameters and effect. 