Radiofrequency ablation (thyroid)

To achieve therapeutic goals we should

reduce the volume enough
avoid complications
minimize recurrence.

Ablation vs. conventional surgery

For treatment, thyroidectomy, which resects the nodule with a half of the thyroid, has traditionally been used. However, as it is a benign nodule, the possibility of a non-operative minimally invasive treatment method has long been studied and used, in consideration of the functional aspect. Thyroid radiofrequency ablation is one of the minimally invasive treatment methods that selectively treats thyroid nodules. It is a same technique used in liver and kidney tumors.

This procedure retains the thyroid parenchyma. So we can preserve the thyroid function. It is also useful because it does not require a neck incision. Its excellent efficacy has been proven though lots of recent studies.

Key Technique for Thyroid Ablation : Moving-shot technique

To maximize ablation effect, every corners of the tumor has to be covered, even if the tumor is shaped irregularly. To do this, multiple small ablation is advantageous to the single large ablation.

The basic idea of moving-shot technique is this, making multiple small ablation zone while moving electrode from one end to the other. To avoid complication, no energy have to be delivered beyond the tumor border. The state of the art technique of this method is making thinnest remnant viable tumors at the periphery while not leaking heat beyond the tumor. To achieve these contradictory goals, rapid strong ablation is favored, which can make smaller ablation zones.

Procedure

Similar with performing a thyroid ultrasonography or biopsy, treatment is done with the patients lying down with their neck fully extended. To minimize damage on the surrounding tissue, the transisthmic approach and moving-shot technique is used. To check the voice of the patients, as well as for complications, the treatment is performed under local anesthesia having conversation with the patients. Although it may vary in accordance with the status and size of the nodule, the treatment is generally completed in about 30 minutes.

Equipment

The tips for thyroid radiofrequency ablation are shorter than tips for other organs. They are designed that way to ensure the manipulation would be easy. There are various electorodes so that the treatment range can vary in accordance with the size of the nodules. The mechanism of irreversible cell damage without carbonization of tissue, is very important in this procedure. As such, the frequently used electrodes has internal cooling system of circulation of water insides of the electrode. On the contrary, for the treatment of small nodules, the electrodes have no internal cooling system. This type of electrodes can control the temperature of the tip with some kind of temperature sensor.

Complication

Several complications associated with radiofrequency ablation have been reported, including hematoma, skin burn, pain, alteration of thyroid function, edema, fever, voice change. Almost all of the complications are transient, but severe complications, such as esophageal perforation, permanent voice change could occur.

Clinical result

According to the many well designed studies, volume of the ablated nodules increased transiently just after the procedure, and reduced to 50 ~ 70% from the original volume at one month and 20 ~ 50% at 6 to 12 months.