Ultrasonography-guided ethanol ablation of predominantly solid thyroid nodules: a preliminary study for factors that predict the outcome

Abstract

Objectives: The aim of this study was to evaluate the success rate in ultrasonography-guided ethanol ablation (EA) of benign, predominantly solid thyroid nodules and to assess the value of colour Doppler ultrasonography in prediction of its success.

Methods: From January 2008 to June 2009, 30 predominantly solid thyroid nodules in 27 patients were enrolled. Differences in the success rate of EA were assessed according to nodule vascularity, nodule size, ratio of cystic component, amount of injected ethanol, degree of intranodular echo-staining just after ethanol injection and the number of EA sessions.

Results: On follow-up ultrasonography after EA for treatment of thyroid nodules, 16 nodules showed an excellent response (90% or greater decrease in volume) and 2 nodules showed a good response (50-90% decrease in volume) on follow-up ultrasonography. However, 5 nodules showed an incomplete response (10-50% decrease in volume) and 7 nodules showed a poor response (10% or less decrease in volume). Statistical analysis revealed a significant association of nodule vascularity (p=0.002) and degree of intranodular echo-staining just after ethanol injection (p=0.003) with a successful outcome; however, no such association was observed with regard to nodule size, ratio of cystic component, amount of infused ethanol and the number of EA sessions. No serious complications were observed during or after EA.

Conclusion: The success rate of EA was 60%, and nodule vascularity and intranodular echo-staining on colour Doppler ultrasonography were useful in predicting the success rate of EA for benign, predominantly solid thyroid nodules.

Figure 1

Four classifications of intranodular echo-staining in greyscale ultrasonography. According to the degree of intranodular echo-staining (arrows) during and just after ethanol injection, a thyroid nodule was classified as (a) no staining, (b) poor staining, (c) mild staining and (d) moderate staining.

Figure 2

A case of successful ultrasonography-guided percutaneous ethanol ablation (EA). Longitudinal (a) greyscale and (b) colour Doppler ultrasonography images of a thyroid nodule in the right lobe in a 32-year-old female showing low vascularity (about 1.3×1.8×2.5 cm). Follow-up ultrasonography images at (c) 5 and (d) 18 months after the second session of EA show moderate shrinkage (about 0.8×0.9×1.3 cm; about 84% decrease in volume) and marked shrinkage (about 0.5×0.5×0.6 cm; about 97.4% decrease in volume), respectively.