Cystic versus predominantly cystic thyroid nodules: efficacy of ethanol ablation and analysis of related factors

Abstract

Objectives: To compare the efficacy of ethanol ablation (EA) of cystic and predominantly cystic thyroid nodules, and to evaluate factors affecting efficacy.

Methods: From October 2008 to December 2010, a total of 217 thyroid nodules were treated with EA. Nodule volumes, symptoms and cosmetic scores were evaluated before and after EA. EA efficacy in treating cystic and predominantly cystic nodules was compared; and factors related to EA efficacy in each type, including initial volume, solid component, vascularity, fluid nature, ethanol retention time and number of EA sessions, were evaluated.

Results: Mean nodule volume decreased from 15.7 ± 18.1 ml to 3.0 ± 7.9 ml (mean volume reduction, 85.2 ± 16.1%) and the therapeutic success rate was 90.3% at last follow-up. EA was significantly more effective in cystic than predominantly cystic nodules. Independent predictors of EA efficacy for all nodules included initial volume, solid component and vascularity. Initial volume and vascularity were independent predictors of EA efficacy in predominantly cystic nodules, but no factor was independently related to efficacy in cystic nodules.

Conclusions: EA is effective in both cystic and predominantly cystic nodules, especially the former. EA is less effective in large or vascular predominantly cystic nodules, but is effective in cystic nodules regardless of related factors.

Key points: • Ethanol ablation under ultrasound guidance is increasingly used for cystic thyroid nodules. • EA seems effective for cystic and predominantly cystic nodules, especially cystic nodules. • The effectiveness of EA was reduced in large or vascular predominantly cystic nodules.