A Prospective Evaluation of High Intensity Focused Ultrasound (HIFU) in the Treatment of Relapsed Graves' Disease

Grave's disease is the most common cause of hyperthyroidism and affects approximately 2% of women and 0.2% of men in the population. The use of antithyroid drugs (ATD) has been the first-line of treatment for Graves' disease in many centers for decades, and its use has been increasing worldwide. One reason for this is that it may induce remission, whereas radioiodine (RAI) and surgery often lead to hypothyroidism and other complications in addition to hospitalization and radiation exposure. However, ATD use is also associated with increasing risk of some adverse minor effects such as skin rash, gastric intolerance, and arthralgia in 5% of patients. Furthermore, major adverse events, such as agranulocytosis and hepatotoxicity may be life-threatening but are rare (<0.5% of cases). These usually occur during the first three to six months of treatment, and tend to be associated with high ATD doses. Therefore, the recommended duration of ATD treatment is generally not longer than 12-24 months. However, despite adequate medical treatment, up to 50-70% of patients with Graves' disease would relapse or recur and therefore, a more definitive approach using RAI treatment or thyroid surgery is eventually needed for the resolution of hyperthyroidism. Although RAI is considered safe and easy to manage, particularly in patients without Grave's ophthalmopathy (GO), subclinical and overt hypothyroidism may occur months or even years after the administration of RAI. Hence, long-term follow-up of thyroid function and GO as well as management of thyroxine replacement is necessary. Similarly, although surgery is the main therapeutic strategy, it carries a 2%-10% risk of complications such as hypocalcemia, transient or permanent recurrent laryngeal nerve palsy, bleeding, or postoperative infection. In view of these, various nonsurgical, minimally invasive treatment alternatives have been developed at specialized treatment centers.

High-intensity focused ultrasound (HIFU) is a noninvasive procedure that involves application of a focused high-energy ultrasound beam for thermal tissue ablation inside the targeted zone, with minimal effect on the surrounding tissue. This method has been applied for treatment of a variety of medical conditions such as uterine fibroids and prostate, breast, pancreatic, and liver tumors. A favorable outcome also has been observed in patients with primary or secondary hyperparathyroidism. HIFU has also been proposed for thyroid nodule ablation . In a human feasibility study, 25 patients were treated 2 weeks before a scheduled thyroidectomy. Pathologic analysis demonstrated targeted tissue destruction of 2%-80% without any damage to neighboring structures. To the investigators knowledge, studies of follow-up after HIFU ablation of Graves' disease have not been published, except for one report where two patients received a combination of microwave ablation and RAI. Thus, the purpose of this prospective study is to assess the short-term efficacy and safety of US-guided HIFU ablation for the treatment of relapsed Graves' disease.