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

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.Livraghi et al [1] used ultrasonography-guided ethanol ablation (EA) for the treatment of hyperfunctioning thyroid nodules; EA has since been established as the first-line treatment for benign cystic thyroid nodules, and may be considered an appropriate alternative to clinical follow-up, radioiodine therapy or thyroid surgery for treatment of autonomous functioning thyroid nodules (AFTNs) or toxic nodules. Advantages of EA include low risk, low cost, practicability in the outpatient clinic and ease of performance [2-14]. However, radioiodine therapy and surgery remain the treatments of choice for large toxic thyroid nodules [5,8,9,15].Following the initial use of EA in the treatment of benign cystic thyroid nodules [16], many published studies have reported appreciable efficacy of EA in the treatment of benign cystic thyroid nodules and recurrent cystic nodules [17-26]. However, published data regarding the EA of solid thyroid nodules have shown varying results, depending on nodule size, the volume of ethanol instilled and the presence of nodule toxicity (2-14]. Thus, the use of EA in the treatment of solid thyroid nodules has been limited owning to controversy over its efficacy and clinical indications. Several studies have attempted to determine factors that might be predictive of the effectiveness of EA in AFTNs or toxic nodules. These studies found that an initial nodule volume [5,8-10] and the presence of a cystic component making up more than 30% of the total volume are important factors in predicting a positive response to EA [14]. Despite these results, EA is rarely selected for the treatment of a solid thyroid nodule compared with the options of clinical follow-up, radioiodine therapy or surgery. Identification of factors that might aid in the accurate prediction of the success of EA in the treatment of solid thyroid nodules could result in more frequent clinical use of EA. To the best of our knowledge, no study of the feasibility of colour Doppler ultrasonography for predicting the success in EA of predominantly solid thyroid nodules has been conducted to date.

Table 1

The published data of ethanol ablation for solid thyroid nodules

Reference number in present study	First author	Year	Type of nodules	Number of patients	Number of sessions	Success rate (%)	Major complication
2	Martino	1992	AFTN	37	1–3	100a	No
3	Mazzeo	1993	AFTN	32	3–10	100a	No
4	Papini	1993	Toxic	20	3–8	100a	No
5	Livraghi	1994	AFTN	101	4–8	58.4b	No
6	Goletti	1994	Cold	20	1–3	100a	No
7	Bennedbak	1995	Cold	13	1	43a	No
8	Di Lelio	1995	AFTN	31	3–7	77b	No
9	Lippi	1996	AFTN	429	2–12	74.6a	No
10	Monzani	1997	Toxic	117	5–10	77.9b	No
11	Zingrillo	1998	Cold	41	2–8	92.7a	No
12	Tarantino	2000	AFTN	12	4–11	100a	No
13	Kim	2003	Solid	22	1–3	35a	No
14	Guglielmi	2004	AFTN	112	2–7	64.2a	No

Open in a separate windowAFTN, autonomous functioning thyroid nodule.^aA success means 50% or more volume reduction rate.^bComplete cure of toxic nodule means that both free thyroid hormone and thyrotropin serum levels returned within the normal range.The aim of this study was to perform an evaluation of the success rate in EA of benign, predominantly solid thyroid nodules and to assess the value of colour Doppler ultrasonography in predicting its success.