Ultrasound-guided radiofrequency ablation results in significant volume reduction for benign thyroid nodules

Cristian Giuseppe Monaco

Two studies presented at the European Congress of Radiology (2–6 March, Vienna, Austria) have found that radiofrequency ablation could have a role in the treatment of thyroid nodules.

The six-month results from the first study presented in the “Ablation outside the Liver” session found that ultrasound-guided radiofrequency ablation of benign thyroid nodules results in 74% volume reduction.

Cristian Giuseppe Monaco and colleagues from Milan, Italy, set out to estimate the effectiveness of ultrasound-guided radiofrequency ablation to treat benign thyroid nodules. They treated nearly 30 patients (six males; with a median age of 60 years) with a biopsy-proven benign thyroid nodule causing compression and/or aesthetic dissatisfaction.

Results from the study showed that the treatment is feasible, safe and effective, and the investigators noted that contrast-enhanced ultrasound is useful to check the effectiveness of the procedure, both immediately and during the follow-up period. Giuseppe Monaco and colleagues carried out ultrasound-guided radiofrequency ablation using a 0.7 or 1cm exposed tip electrode. Contrast-enhanced ultrasound was performed to determine the avascular portion of the tumour and the need for immediate re-intervention. Follow-up included ultrasound and contrast-enhanced ultrasound after one and six months. They also measured volume and calculated percent variations and compared them to pre-treatment values using the Wilcoxon test. Data were given as median and interquartile range.

The investigators found that median pre-treatment volume was 20ml with the avascular portion being 13ml. At one-month follow-up, the median nodule volume reduced to 9ml (p<0.001), corresponding to a reduction of 60% with the the avascular part being reduced to a median of 5ml, corresponding to a reduction of 59%. At six-months, the nodule volume reduced to 4ml (p<0.001), corresponding to a reduction of 74% and the avascular part reduced to 2ml, corresponding to a reduction of 84%.

After the procedure, 5/28 patients reported moderate pain whilst 2/28 patients developed a haematoma that was spontaneously reabsorbed. All patients reported relief of initial symptoms at one and six months.

Another study presented at the same session was a single-centre experience from Pisa, Italy. The investigators used radiofrequency ablation as an alternative local treatment for hyperfunctional solid thyroid nodules.

Rosa Cervelli and colleagues set out to validate the efficacy and safety of radiofrequency ablation for treating autonomously functioning thyroid nodules.

Based on the results of the study, the authors concluded that the efficacy and safety of radiofrequency ablation in treating autonomously functioning thyroid nodules. “Radiofrequency ablation can be considered a suitable treatment instead of conventional therapy (surgery or radio iodine therapy), especially for patients with pre-toxic benign nodules. In fact, this technique only affects pathological areas and preserves all the remaining thyroid gland,” they wrote.

They treated 15 nodules in 13 patients (11 females; 59±11 years) with toxic and pre-toxic autonomously functioning thyroid nodules, who refused or were not suitable for surgery or radioiodine therapy in a single session of radiofrequency ablation.

“The ablation was performed in real-time with ultrasound guidance and local pericapsular anaesthesia, using an 18-gauge, internally cooled electrode. Nodule volume, thyroid function, ultrasound, contrast enhancement US (CEUS) and scintigraphic evaluations, before therapy and during six months of follow-up, were performed. Physical parameters (basal impedance, power, application time) of the machine were recorded,” Cervelli said.

Cervelli and colleagues found that radiofrequency power ranged between 35 and 45W. The mean application time was 9.34±5.09 minutes, depending on nodule size. The mean of pre-treatment nodule volume was 13.5±13.3mL. The nodule size decreased in all cases (3.9±3.1 mL at six-month follow-up) with a mean volume reduction rate of 74.2%, six months after treatment (p=0.0005). “Significant improvement of thyroid function was observed at last follow-up. As to scintigraphy, all hot nodules became cold or normal when scanned. No major complications were detected,” Cervelli said.