Ablating a Benign Thyroid Nodule with an Ultrasound-Guided High-Intensity Focused Ultrasound Ablation Device

Introduction: Benign thyroid nodules are common. Although most of them do not grow and cause pressure symptoms, some may become symptomatic with time. Thermal ablation is a recognized treatment modality in enlarging or symptomatic single thyroid nodule. High-intensity focused ultrasound (HIFU) is one form of thermal ablation techniques for this situation. The aims of the video were to describe how this technique is done, what the pros and cons are, and what outcomes are expected after treatment. Materials and Methods: The video began with a case scenario of a 63-year-old woman with a left-sided thyroid nodule. The nodule was aspirated twice and the cytology in both occasions turned out to be benign. On ultrasound, it appeared to be a benign nodule in left thyroid lobe and the nodule comprised 50% cystic area. The total nodule volume was 5.1 × 3.2 × 3.7 cm (or estimated volume of 30.19 cc). She was symptomatic with dysphagia and neck pressure. Results: HIFU works by focusing ultrasound waves into the center of the target. However, since it can only heat up one small point of the target nodule at any given time, to be able to completely ablate an entire nodule, the treatment head needs to move from one place to another (or the so-called “moving shot” technique) in a systematic manner. This process is done automatically once the target has been clearly marked on the touchscreen of the device by the operator. The device will then draw egg-shaped circles inside the target nodule. Each circle represents a voxel or subunit. Each subunit will then receive a fixed duration of treatment pulses, which then translate into heat and energy. A fair amount of hyperechoic marks or microbubbles can often be seen inside the target, signifying effective heating of the target. At the completion of the treatment, it is expected that a fair amount of microbubbles could be seen in central region of the target nodule. On average, after one application, the shrinkage is close to 50% to 60% volume reduction relative to that of the baseline. Symptoms are also expected to improve. Second application is sometimes required when symptoms persist or if there is interval enlargement in the follow-up period. Conclusion: HIFU is one form of thermal ablation techniques that has been proven to be effective and safe in patients with a symptomatic or enlarging benign thyroid nodule. Patient consent was received and archived before recording. No competing financial interests exist. Runtime of video: 7 mins 9 secs