Laser Ablation of Benign Thyroid Nodules: A Prospective Pilot Study With a Preliminary Analysis of the Employed Energy

Abstract

Background and Objectives To assess the effectiveness of ultrasound (US)‐guided laser ablation of benign thyroid nodules (TNs) under different amounts of applied energy. Study Design/Materials and Methods Thirty‐four euthyroid patients with 5–18 ml TNs were enrolled: 21 (laser ablation) and 13 (clinical follow up) patients with a mean age of 56.2 ± 12.0 and 54.7 ± 14.7 years, respectively. The laser ablation protocol used a 1.064 mm wavelength diode laser source; 3.5 W output power; 1,100–1,500 J and 5–8 min/illumination; and one or two fibers/session. Clinical, laboratory, and US data were obtained immediately before treatment and at 6 and 12 months follow‐up and were analyzed by Student's t test and Fisher's exact test. Low‐ and high‐energy subgroups were subsequently defined, and the receiver operating characteristic (ROC) curves were calculated. Results Laser ablation follow‐up showed an overall nodule volume reduction of more than 50%; improvement of symptoms and cosmetic complaints (P = 0.001); and stable laboratory data compared with the baseline and control groups. Minor complications were 9.5% ( n = 2). One or two fibers/session resulted in a similar nodule volume reduction among 10–18 ml nodules. Analysis of the applied energy suggested a 398.8 J/ml inferior cutoff (ROC curve: 0.889 sensitivity; 0.545 specificity) for the high‐energy subgroup ( n = 14, mean 599.9 ± 136.5 J/ml) to reduce the nodule volume over time (−55.1% vs. −58.4%, P = 0.55). The low‐energy subgroup ( n = 7, mean 240.2 ± 74.6 J/ml) did not show a persistent volume reduction ( P < 0.05) from the 6‐ to 12‐month follow‐ups (−56.6% vs. −53.7%). Conclusions Laser ablation of benign TNs achieved technique efficacy at 12 months posttreatment, with clinical improvement and few minor side effects. A single fiber in a single session with a high deployed energy (>398.8 J/ml) may be associated with improved results, a finding to be confirmed with a larger series. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

Twelve-Month Volume Reduction Ratio Predicts Regrowth and Time to Regrowth in Thyroid Nodules Submitted to Laser Ablation: A 5-Year Follow-Up Retrospective Study

“…A recent study showed that when using laser ablation, higher energy deployment may be associated with improved results; between two groups of nodules undergoing different energy treatments, the one treated with a mean of 599.9 ± 136.5 J/ mL obtained a VRR greater than the one treated with a mean of 240.2 ± 74.6 J/mL. The authors calculated that > 398.8 J/ mL should be used to obtain better results (26). Though one might hypothesize that the regrowth rate we observed was influenced by the relatively low amount of energy supplied, the results undoubtedly showed that similar amounts of energy exerted different results in terms of VRR.…”

Single‐Fiber Laser Ablation in Treating Selected Metastatic Lymph Nodes of Papillary Thyroid Carcinoma and Benign Cold Thyroid Nodules—Preliminary Results

“…For benign cold thyroid nodules, clinical follow‐up and several ablative methods, including LA, RFA, MWA, and HIFU, have been applied to these nodules and these ablative methods have demonstrated good results, and LA appears to be superior to the other methods, due to its advantages. A prospective pilot study demonstrated that LA group achieved technique efficacy and clinical improvement in contrast to clinical follow‐up group . A 3‐year, multicenter, prospective randomized trial demonstrated that LA obtained long‐term efficacy, with an absence of thyroid function changes .…”

“…As different tissues have different characteristics, such as the amount of colloid, both fibrosis and vascularity may possibly account for the different optical properties of the nodule, thereby resulting in differences in responsiveness and a demand for the amount of deposited energy . In this study, a 5‐ml‐volume upper limit existed for the benign cold thyroid nodules, which is only a preliminary inclusion that was dependent on our experiences and previous studies . However, the feasibility and effectiveness of ultrasound‐guided single‐fiber LA were evaluated, and the appropriate ablation modes for these selected nodules were performed.…”

“…Fiber movements were followed certain orders: ablating the deep part of the nodule and then the superficial to reduce the interference caused by the hyperechoic areas generated by the ablation; ablating the nourish blood vessels of the nodule and then the body to reduce less affected by the heat‐sink effect . According to our clinical practice and research reports, LA was performed with an output power of 3 W or 3.5 W in the metastatic lymph nodes of PTC and with an output power of 4 W in the benign cold thyroid nodules . The ablation time and energy was dependent on the individual nodules and was achieved by using an adequate exposure time and deposited energy to produce a complete ablation.…”

“…The concept of laser ablation (LA) was first proposed by British scholar Bown , and it refers to the conversion of laser light energy into heat energy, which causes localized biological tissue to coagulate, as well as to undergo necrosis, carbonization, gasification, and even evaporation . LA is utilized in many surgical fields, such as surgeries for the liver, thyroid, metastatic lymph nodes, parathyroid glands, breast, kidney, prostate, and other body organs . Other competitive procedures include percutaneous ethanol injection (PEI), radiofrequency ablation (RFA), microwave ablation (MWA), and high‐intensity focused ultrasound (HIFU) .…”