Abstract
KEY POINTS
Thyroid artery embolization (TAE) produced clinically significant and durable volume reduction in patients with large multinodular goiter, with mean reductions of 60% in total thyroid volume and 68% in dominant nodule volume at 24 months.
Only 7.5% of patients required retreatment despite initial mean thyroid volume exceeding 100 mL; there was no difference in outcomes in cases of substernal extension.
A major complication rate of 5% was reported, which included a cerebellar stroke with eventual recovery and a hematoma requiring drainage. Transient thyrotoxicosis occurred in 22% of patients.
TAE may represent a useful alternative for selected patients with very large multinodular goiters who cannot or will not undergo surgery and would otherwise require multiple percutaneous thermal ablation sessions.
SUMMARY
Background
Surgery remains the standard treatment for symptomatic multinodular goiter, especially in cases of large nodules and/or substernal extension; however, some patients are not surgical candidates or will refuse surgery. 1 Percutaneous thyroid ablation techniques such as radiofrequency ablation (RFA) and microwave ablation (MWA) have emerged as alternatives but are generally more effective in patients with single, smaller thyroid nodules.2,3
Thyroid artery embolization (TAE) is an endovascular technique that induces ischemic involution of thyroid tissue through selective embolization of the thyroid arterial supply. Prior studies have demonstrated promising results, but data remain limited regarding long-term outcomes and safety in patients with benign symptomatic multinodular euthyroid goiters.4,5 The objective of this study was to evaluate the efficacy of TAE with follow-up extending to 24 months. 6
Methods
This retrospective single-center study included consecutive patients with symptomatic benign multinodular euthyroid goiters treated with TAE between December 2021 and June 2024. All patients had been offered surgery but either declined or were considered poor surgical candidates. Treatment decisions (surgery vs. percutaneous ablation vs. TAE) were made via multidisciplinary discussion and were based on the clinical picture and patient preference. TAE was preferred for patients with large multinodular glands, multiple nodules, or substernal extension. Nodules were confirmed to be benign on biopsy, and thyroid function tests were normal. Patients with suspected malignancy, contraindications to angiography, uncontrolled coagulopathy, pregnancy, or incomplete follow-up were excluded.
Baseline assessment included thyroid function testing, ultrasound, and CT imaging. Total thyroid volume and dominant nodule volume were measured before treatment and at 12- and 24-month follow-up. TAE was performed by a single experienced interventional radiologist via transfemoral catheterization using selective embolization of thyroid arteries with 500- to 700-μm microspheres with a target angiographic endpoint of near stasis.
Primary end points included changes in total thyroid volume and dominant nodule volume. Secondary end points included symptom resolution, cosmetic improvement, recurrence, reintervention, and complications. Adverse events were classified using Society of Interventional Radiology criteria.
Results
Forty (24 male, 16 female) of 46 patients were included after attempted TAE. One patient was excluded because of technical failure, and 5 were lost to follow-up. Mean (±SD) total thyroid volume decreased from 118.45 ± 36.60 mL (range, 55–212 mL) at baseline to 54.78 mL at 12 months (53% reduction) and 46.73 mL at 24 months (60% reduction). The mean dominant nodule volume decreased from 31.60 mL to 14.59 mL at 12 months (53% reduction) and 10.08 mL at 24 months (68% reduction).
Symptom resolution was achieved in 95% of patients at 12 months and 97.5% at 24 months. Cosmetic scores improved significantly by 12 months, with no statistically significant additional improvement between 12 and 24 months. Recurrence occurred in one patient (2.5%), attributable to collateral revascularization, and that patient underwent repeat TAE. Two additional patients (5%) required MWA for newly symptomatic nodules outside the previously embolized territory; these were classified as new disease rather than true recurrence. The overall reintervention rate was 7.5%. Patients with substernal extension (40%) had similar outcomes to those with cervical goiters.
Transient biochemical hyperthyroidism occurred in 9 patients (22.5%) and generally resolved within 2 months. No cases of hypothyroidism or hypoparathyroidism were reported. Major complications included one cerebellar infarction (patient also had factor V Leiden mutation) noted immediately and one perithyroidal hematoma noted 1 month after the procedure, requiring drainage (5%). Both patients recovered without permanent sequelae.
Conclusions
TAE resulted in substantial and sustained thyroid volume reduction with high rates of symptom improvement and low recurrence during 24 months of follow-up. TAE represents a viable alternative to surgery in selected patients with benign symptomatic multinodular euthyroid goiters, although the risk of stroke is not insignificant.
COMMENTARY
TAE is limited to a few centers with the requisite expertise, and consequently, there is a paucity of data describing outcomes.4,5,7 This study adds meaningful longer-term data and highlights one of the main reasons why TAE is performed only at specialized centers—the nonnegligible risk of stroke due to nontarget embolization or catheter-related thromboembolism, which can potentially be devastating.
The complication rate deserves discussion, as it is reported at 35%, which appears unacceptable; however, it is mostly represented by patients experiencing postprocedure thyrotoxicosis (22%). This is presumably because of self-limiting thyroiditis, although it would have been interesting to see I-123 uptake and scans, since the study mentions that some patients required thionamides. An argument might be made to consider this a side effect rather than a complication—one that requires careful monitoring, especially in older patients or those with cardiovascular disease.
A major complication rate of 5% is not insignificant, but it is also not substantially different from reported complication rates for thyroidectomies (5.7%), 8 though it is higher than major complication rates for percutaneous thyroid ablation (1.9%). 9 The authors note that the patient who developed a cerebellar infarction was subsequently found to have a factor V Leiden mutation. Whether this caused a predisposition to the event is unclear; however, careful assessment of personal and family thrombotic history before embolization appears prudent.
It is worth noting that significant morbidity and mortality have been reported after TAE in the literature, largely related to nontarget embolization, including cerebrovascular events, visual loss, and laryngeal injury with subsequent aspiration pneumonia; deaths due to stroke and thyroid storm have also been reported. 10
The major limitation of this study is the absence of a comparison group, though inferences can be made from reported literature. The volume reduction is comparable to percutaneous thermal ablation, 2 though it is worth noting that even after treatment the goiter and nodule size is quite large. The favorable symptom reduction results are likely a consequence of the large absolute volume reduction (as opposed to percentage) and a selection bias, as patients who specifically chose the procedure are more likely to report that it went well.
Only three patients required retreatment during the follow-up period, which speaks to the efficacy and durability of the procedure. Given these results, TAE would be especially useful to consider in patients who will not or cannot get surgery for goiters that are substernal or over 100 mL in volume and thus may respond inadequately to percutaneous thyroid ablation.2,3 It is no surprise that cervical and substernal goiters respond similarly to TAE, since the treatment treats the thyroid globally through devascularization of the arterial supply.
In my practice, I routinely discuss all viable surgical and nonsurgical options with patients with symptomatic, benign multinodular goiters. Many patients who do not want surgery are candidates for RFA or MWA; however, there is a subset of patients with very large multinodular goiters, multiple dominant nodules, or substernal extension for whom I will suggest that they consider TAE at a specialized, high-volume center. I will also counsel these patients regarding potential stroke risk, and this often ends up being a deciding factor in the patients’ decision-making process. Sometimes we will also consider a combination of approaches, including both embolization and thermal ablation for extensive multinodular disease.