Radiofrequency ablation (thyroid)

Radiofrequency ablation is an effective and minimally invasive method to treat symptomatic benign thyroid nodules.

To achieve therapeutic goals we should

  1. reduce the volume enough
  2. avoid complications
  3. 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.

Suggested Readings

  1. Radiofrequency ablation of benign thyroid nodules and recurrent thyroid cancers: consensus statement and recommendations. Na DG1, Lee JH, Jung SL, Kim JH, Sung JY, Shin JH, Kim EK, Lee JH, Kim DW, Park JS, Kim KS, Baek SM, Lee Y, Chong S, Sim JS, Huh JY, Bae JI, Kim KT, Han SY, Bae MY, Kim YS, Baek JH; Korean Society of Thyroid Radiology (KSThR); Korean Society of Radiology. Korean J Radiol. 2012 Mar-Apr;13(2):117-25. doi: 10.3348/kjr.2012.13.2.117. Epub 2012 Mar 7.
  2. Radiofrequency ablation of thyroid nodules: basic principles and clinical application. Shin JH1, Baek JH, Ha EJ, Lee JH. Int J Endocrinol. 2012;2012:919650. doi: 10.1155/2012/919650. Epub 2012 Oct 22.
  3. Radiofrequency ablation of benign non-functioning thyroid nodules: 4-year follow-up results for 111 patients. Lim HK1, Lee JH, Ha EJ, Sung JY, Kim JK, Baek JH. Eur Radiol. 2013 Apr;23(4):1044-9. doi: 10.1007/s00330-012-2671-3. Epub 2012 Oct 25.
  4. Radiofrequency ablation compared to surgery for the treatment of benign thyroid nodules. Bernardi S1, Dobrinja C2, Fabris B1, Bazzocchi G3, Sabato N1, Ulcigrai V4, Giacca M2, Barro E1, De Manzini N2, Stacul F3. Int J Endocrinol. 2014;2014:934595. doi: 10.1155/2014/934595. Epub 2014 Jun 22.
  5. Advances in nonsurgical treatment of benign thyroid nodules. Ha EJ1, Baek JH. Future Oncol. 2014 Jun;10(8):1399-405. doi: 10.2217/fon.14.59.
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