Microwave ablation for thyroid nodules: a new string to the bow for percutaneous treatments?

Abstract

Background: Thyroid nodules are a fairly common finding in general population and, even if most of them are benign, a treatment can be however necessary. In the last years, non surgical minimally invasive techniques have been developed to treat this pathology, starting from percutaneous ethanol injection (PEI), to laser ablation (LA), radiofrequency ablation (RFA) and, most recently, microwave ablation (MWA).

Methods: We reviewed all medical literature searching in pubmed.gov the terms "microwave" & "thyroid". We found three original studies concerning MWA treatment, for a total of 263 patients (mean age 51.0 years; range, 15-80 years; male to female ratio 2.55) and 522 nodules.

Results: A total of 522 nodules (338 solid, 22 cystic, 162 mixed) in 263 patients were treated. Studies have shown a mean reduction in volume of thyroid nodules ranging from 45.9% to 65%. No study reported a significant and definitive change in laboratory parameters, except for one case (Heck et al.). No studies have reported major complications after procedure.

Conclusions: MWA is a new, promising technique among the minimally invasive treatments of thyroid nodules. Actually, the larger diameter of MW antenna seems to be the major limiting factor in the use of this technique. More studies are necessary to evaluate feasibility, safety and efficacy of the procedure.

Keywords: Ablation techniques; microwaves; thyroid nodule.

Figure 1

US view of the MW antenna in a thyroid nodule. US, ultrasound; MW, microwave.

Figure 2

MW ablation of the nodule under US-guidance; note the hyperechoic area created by ablation. MW, microwave; US, ultrasound.

Figure 3

Pre-ablation measurement of a mostly cystic thyroid nodule (volume: 9.8 cc).

Figure 4

US control at 1 year after MW ablation of the thyroid nodule, showing reduction of 71.4% of the volume. US, ultrasound; MW, microwave.