Predictor Analysis in Radiofrequency Ablation of Benign Thyroid Nodules: A Single Center Experience

Abstract

PurposeTo confirm the efficacy of ultrasound (US) guided radiofrequency ablation (RFA) in the treatment of benign thyroid nodules, we evaluated as primary outcome the technical efficacy and clinical success in a single center dataset. The secondary outcome was to find a correlation between nodules’ pre-treatment features and volume reduction rate (VRR) ≥75% at 12 months after RFA and during follow-up period.MethodsThis retrospective study included 119 consecutive patients (99 females, 20 males, 51.5 ± 14.4 years) with benign thyroid nodules treated in our hospital between October 2014 and December 2018 with a mean follow-up of 26.8 months (range 3–48). Clinical and US features before and after RFA were evaluated by a US examination at 1, 3, 6, 12 months and annually thereafter up to 48 months.ResultsThe median pre-treatment volume was 22.4 ml; after RFA we observed a statistically significant volume reduction from the first month (11.7 ml) to the last follow-up (p < 0.001 for all follow-up times). The median VRR was 47.1, 55.3, 61.2, 67.6, 72.8, 71.3, and 62.9% at 1, 3, 6, 12, 24, 36, and 48 months of follow-up respectively, showing a progressive significant improvement up to 24 months (VRRs 1 vs 3 months, 3 vs 6 months and 6 vs 12 months p < 0.001, 12 vs 24 months p = 0.05) while no differences at 24 vs 36 and 36 vs 48 months were observed. Symptoms improved significantly (complete resolution 64.35%, partial resolution 35.65%), and neck circumference was reduced as compared to pre-treatment (p < 0.001). Lower pre-treatment neck circumference (37.5 vs 36.0 cm, p = 0.01) was a positive predictor of VRR ≥75% at 12 months. Macrocystic echostructure (HR 2.48, p 0.046) and pre-treatment volume >22.4 ml (HR 0.54, p 0.036) were found to be independent positive and negative predictors of VRR ≥75% respectively. One-month post RFA VRR ≥50% represented the best positive predictor of technical success.ConclusionsThis study confirmed the efficacy of RFA in the treatment of benign thyroid nodules. In particular we show that by selecting macrocystic nodules smaller than 22.4 ml better long-term response can be achieved, which is predicted by an early shrinkage of the nodule.

Clinical and functional results of radiofrequency ablation and microwave ablation in patients with benign thyroid nodules

“…Alternative and minimally invasive methods include RFA, MWA, EA, and PLA. 14 - 20 Ethanol ablation is frequently used in the minimally invasive treatment of cystic thyroid nodules as an alternative to surgery. 16 , 17 , 26 Radiofrequency ablation has also been shown to be a successful alternative to surgical therapy as it provides local ablation of BTN via thermal energy.…”

“…1- no palpable nodule, 2- a palpable nodule with no cosmetic problem, 3- the presence of nodules visible by swallowing, and 4- the presence of prominent nodules, according to this scoring system ( Figure 1 ). 20 , 26 …”

“… 13 , 19 In one of the recent studies, a decrease in volume of 30-60% at one month follow-up, and 50-85% at 6 months was detected in benign cold thyroid nodules treated with RFA, as well as a decrease in cosmetic complaints and compression symptoms. 20 After the radiofrequency treatment was applied for autonomic thyroid nodules, it was determined that the high thyroid hormone levels before treatment returned to normal, and also there was a reduction in the size of the nodules. 19 , 20 Although complications of RFA application such as pain, voice change, hematoma, skin burn, thyrotoxicosis, hypothyroidism, fever can occur, the majority of patients recovered over time without a permanent sequela.…”

“… 20 After the radiofrequency treatment was applied for autonomic thyroid nodules, it was determined that the high thyroid hormone levels before treatment returned to normal, and also there was a reduction in the size of the nodules. 19 , 20 Although complications of RFA application such as pain, voice change, hematoma, skin burn, thyrotoxicosis, hypothyroidism, fever can occur, the majority of patients recovered over time without a permanent sequela. 21 , 22 …”

Ultrasound grayscale ratio: a reliable parameter for differentiating between papillary thyroid microcarcinoma and micronodular goiter

“…Thyroid lesions are divided into five categories based on the comparison of echogenicity between the cervical strap muscle and thyroid: anechoic, markedly hypoechoic (echogenicity lower than that of the cervical strap muscle), hypoechoic (echogenicity between that of the cervical strap muscle and thyroid parenchyma), isoechoic (with the same echogenicity as the thyroid parenchyma), and hyperechoic (more echoic than the thyroid parenchyma) [ 1 – 3 ]. The diagnostic values of the hypoechoic and markedly hypoechoic categories have been widely accepted for thyroid malignant nodules [ 1 , 4 – 7 ]. However, distinguishing between hypoechoic and markedly hypoechoic categories is a subjective process that is influenced by the observer’s judgment.…”