A prospective study on the efficacy of single high intensity focused ultrasound treatment of patients with benign symptomatic thyroid nodule

Abstract

Background: Benign thyroid nodules are prevalent among the general population and some nodules may exhibit growth over time leading to compression symptoms or cosmetic concerns. Although surgery remains the treatment of choice for symptomatic thyroid nodule, it is associated with a 2%–10% risk of complications and requires a general anesthesia. The aims of the present study were to assess the efficacy of a single treatment of high intensity focused ultrasound (HIFU) in reducing benign thyroid nodule volume and to evaluate the changes in health-related quality of life (HRQL) following a single HIFU treatment. Materials and Methods: After obtaining IRB approval, consecutive patients with symptomatic thyroid nodule were assessed for eligibility. Inclusions were nodule(s) (1) without signs of malignancy (i.e. no suspicious clinical and ultrasonic features and benign cytology on fine needle aspiration), (2) measuring ≥10 mm on ultrasound (USG) in three orthogonal dimensions, (3) amenable to HIFU. Exclusions were nodule(s) (1) measuring<40mm (by largest dimension), (2) located <2mm from trachea, esophagus or recurrent laryngeal nerve (where ablation might pose thermal injury). Eligible patients were offered a choice of HIFU treatment, active observation or surgical resection. HIFU treatment was conducted with the USG-guided Echopulse (Theraclion SA, France). Primary outcome was a change in index thyroid nodule volume 6 months after HIFU. To have 80% power and 95% confidence interval (two-sided) to detect minimal important difference of 20%, 20 patients were needed. Assuming a 10% incomplete and withdrawal rate, 22 patients were required. Thyroid volume (mL) was assessed at baseline (i.e. before ablation) (Figure 1), 1-week, 3-month and 6-month (Figure 2) while HRQL was assessed by the Chinese version of the SF-12v2 at baseline and 6-month. The HRQL measured by eight domain scores and two summary scores (physical and mental component summary) was then compared between those who received HIFU and those who chose active observation (controls) at 6-month. Results: Over this period, 22 (52.4%) chose to receive a single course of HIFU (HIFU group) while the other 20 patients chose to have active observation (controls). Among the HIFU group, the majority were females (90.9%) and the majority (77.3%) had their index nodule as the dominant nodule in a multinodular goiter. The mean base index nodule volume was 6.48 ± 4.34mL (range: 0.92 - 16.76mL). At 6-month following HIFU, the treated nodule volume decreased to 1.38 ± 1.31 mL (n=22, p<0.001). The average extent of nodule reduction was 71.58 ± 11.81% (range: 54.45 – 90.09%). However, there was no significant correlation between extent of 6-month volume reduction and basal volume (r=0.096, p=0.806), total treatment time (r=0.503, p=0.168), total energy delivered (r=0.122, p=0755) or mean delivered energy per treated volume tissue (r=0.150, p=0.700). Compared with controls, the HIFU group achieved a significantly greater improvement in four quality-of-life domains (17.57 ± 6.46, p=0.009 for role physical; 18.01 ± 6.78, p=0.011 for bodily pain; 24.77 ± 8.15, p=0.004 for general health; 32.61 ± 8.93 for social functioning), and physical component summary of the SF-12v2 ((7.89 ± 2.83, p=0.001). Conclusions: USG-guided HIFU ablation is not only an effective and safe treatment option for patients with benign symptomatic thyroid nodules but has the potential of improving the HRQL of patients who do not wish to undergo surgical resection.