Ultrasound-guided ethanol ablation for cystic thyroid nodules: effectiveness of small amounts of ethanol in a single session

Abstract

Purpose: The aim of this study was to evaluate the efficacy of ethanol ablation (EA) in the treatment of cystic thyroid nodules using low-dose ethanol regardless of the initial volume of the nodule or properties of the aspirate.

Methods: Sixty-one nodules in 60 patients were treated with EA from October 2013 to January 2020. In each patient, EA was performed only once, using less than 5 mL of ethanol (99.5%) instilled and removed completely after a few minutes of retention. Nodule volume, the symptom score, the cosmetic score, and complications were evaluated before and after treatment. The therapeutic success rate (TSR) and volume reduction rate (VRR) according to nodule volume and properties of the aspirate were evaluated. Therapeutic success was defined as the absence of any residual fluid or sufficient volume reduction (≥50%) with improvement of nodule-related symptoms.

Results: The 61 nodules comprised 38 pure cysts and 23 predominantly cystic nodules. The initial nodule volume was 21.9±15.2 mL (range, 4.4 to 77.2 mL). The TSR was 88.5% (100% in pure cysts and 69.6% in predominantly cystic nodules, P<0.001). The TSR of pure cysts was 100% regardless of nodule volume and properties of the aspirate. In predominantly cystic nodules, the TSR and VRR gradually decreased as volume increased. One patient experienced arrhythmia during the procedure, but completely recovered without sequelae.

Conclusion: Single-session EA using low-dose ethanol might be effective for the treatment of symptomatic cystic thyroid nodules regardless of the initial cyst volume and properties of the aspirate, especially in pure cysts.

Keywords: Ablation; Ethanol; Sclerotherapy; Thyroid; Thyroid cyst; Thyroid nodule.

Fig. 1.. Flowchart of the patient selection process.

EA, ethanol ablation; FU, follow-up.

Fig. 2.. Ultrasonography during ethanol ablation.

When ethanol is instilled, the inner surface of the cyst (arrow) (A) is changed to a hyperechoic line (arrowhead) (B).

Fig. 3.. Success rates of ethanol ablation by initial nodule volume (overall and subgroups).

Success was defined as the disappearance of the cystic component, or a nodule volume reduction greater than 50% at the end of follow-up with improvement of nodule-related symptoms. Regardless of the target nodule volume, the success rate reached 100% in all pure cysts. In predominantly cystic nodules, the success rate showed a tendency to decrease as the target nodule volume increased. In each volume fraction, a comparison between subgroups showed no statistically significant differences (P-values calculated by the Mann-Whitney U test).