Percutaneous Ethanol Injection of Complex Cystic Thyroid Nodules: Nodule Selection and Techniques

Ultrasound-guided percutaneous ethanol injection (PEI) is an effective method to shrink symptomatic simple thyroid cysts and benign complex cystic nodules. The cystic content is drained using an appropriate gauge needle and 95% ethyl alcohol is injected into the cyst cavity. The ensuing inflammation and desiccation of the tissue lining the cyst walls lead to adhesion and sclerosis resulting in obliteration of the cyst cavity. The effectiveness of this procedure depends upon the complete emptying of the cyst contents and avoidance of intracavitary bleeding during the aspiration and injection process. The use of Z-track or transisthmic insertion of the needle reduces alcohol leakage, particularly when large bore needles are required for the aspiration of viscid fluid. Thin-walled unilocular simple cysts with floppy walls are particularly responsive to PEI. Complex cystic nodules or cystic nodules with septations respond variably. The proportion of the cystic versus solid nature determines the choice of initial treatment, aspiration, and PEI is favored for nodules that are >50% cystic. Radio frequency ablation (RFA) is generally conducted for solid nodules or predominantly solid nodules. If the cystic component is <30%, the cyst fluid may be absorbed spontaneously after RFA. The solid mural component may be located as a discrete eccentric lesion or as a concentric mural mass with uniformly thick vascularized walls. The latter is hard to treat with either PEI or RFA. This is because of arterialized vasculature that results in nodule regrowth. These cysts also give the impression of “formation of a solid nodule,” as fluid portion is being aspirated. In this section, examples of complex cystic nodules and injection of cystic nodules are reviewed. Techniques to avoid alcohol extravasation, risk reduction, and safety policies are also briefly discussed. No competing financial interests exist. Patient consent for image gathering and the potential use for teaching/publication was obtained along with routine patient care at the University of Utah and the Huntsman Cancer Center. Runtime of video: 9 mins 43 secs