Significance of hyperechoic marks observed during high-intensity focused ultrasound (HIFU) ablation of benign thyroid nodules

Efficacy of HIFU for the treatment of benign thyroid nodules: a systematic review and meta-analysis

OBJECTIVE

Thyroid nodules are common and sometimes associated with cosmetic issues. Surgical treatment has several disadvantages, including visible scarring. High-intensity focused ultrasound (HIFU) is a recent noninvasive treatment for thyroid nodules. The present study aims to evaluate the effectiveness and safety of HIFU for the treatment of benign thyroid nodules.

METHODS

We searched PubMed, Embase, and Cochrane Library for studies evaluating the outcomes of HIFU for patients with benign thyroid nodules. We conducted a meta-analysis by using a random effects model and evaluated the volume reduction ratio, treatment success rate, and incidence of treatment-related complications.

RESULTS

Thirty-two studies were included in the systematic review. Only 14 studies were used in the meta-analysis because the other 18 involved data collected during overlapping periods. The average volume reduction ratios at 3, 6, and 12 months after treatment were 39.02% (95% CI: 27.57 to 50.47%, I2: 97.9%), 48.55% (95% CI: 35.53 to 61.57%, I2: 98.2%), and 55.02% (95% CI: 41.55 to 68.48%, I2: 99%), respectively. Regarding complications, the incidences of vocal cord paresis and Horner's syndrome after HIFU were 2.1% (95% CI: 0.2 to 4.1%, I2: 14.6%) and 0.7% (95% CI: 0 to 1.9%, I2: 0%), respectively.

CONCLUSIONS

HIFU is an effective and safe treatment option for patients with benign thyroid nodules. However, the effects of HIFU on nodules of large sizes and with different properties require further investigation. Additional studies, particularly randomized controlled trials involving long-term follow-up, are warranted.

CLINICAL RELEVANCE STATEMENT

Surgical treatment for thyroid nodules often results in permanent visible scars and is associated with a risk of bleeding, nerve injury, and hypothyroidism. High-intensity focused ultrasound may be an alternative for patients with benign thyroid nodules.

KEY POINTS

• The success rate of HIFU treatment for thyroid nodules is 75.8% at 6 months. Average volume reduction ratios are 48.55% and 55.02% at 6 and 12 months. • The incidence of complications such as vocal fold paresis, Horner's syndrome, recurrent laryngeal nerve palsy, hypothyroidism, and skin redness is low. • HIFU is both effective and safe as a treatment for benign thyroid nodules.

Single-session high-intensity focused ultrasound (HIFU) ablation for benign thyroid nodules: a systematic review

BACKGROUND

Thyroid nodules are common; the majority of them are benign and asymptomatic. Thyroidectomy might be an option; however, the frequency of post-operative complications mandates the development of alternative approaches, such as high-intensity focused ultrasound ablation (HIFU). HIFU induces thermal destruction without penetrating the skin. The present systematic review aims to synthesize all available data, evaluating studies with single-session HIFU therapy and investigating its efficacy.

MATERIALS AND METHODS

This systematic review was conducted in accordance with the PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and MetaAnalyses). Eligible articles were identified by a search of Medline bibliographic database (PubMed) and Cochrane Library. Out of 39 results, 11 articles were considered to meet the inclusion criteria.

RESULTS

All eligible studies included patients with solid or predominantly solid benign thyroid nodules. All patients were treated with the same HIFU device. The success rate of the method was defined in the majority, with the volume reduction rate (VRR) over 50% from baseline. The mean or median VRR ranged from 48.7 to 70.41%, depending on the last follow-up date. No major complications were observed.

CONCLUSION

Single-session HIFU is safe and effective for the treatment of benign thyroid nodules.

Identifying predictive factors for efficacy in high intensity focused ultrasound (HIFU) ablation of benign thyroid nodules - a retrospective analysis

Objective: Since it is unclear whether clinical parameters can independently predict the subsequent treatment response following high intensity focused ultrasound (HIFU) ablation of benign thyroid nodules, we aimed to examine clinical factors that may independently predict 12-month efficacy after HIFU treatment.Methods: One hundred and forty patients who had single ablation were categorized into two groups, those with 12-month nodule shrinkage above the median (Group I, n = 70) and with shrinkage below or equal to the median (Group II, n = 70). Baseline characteristics, treatment parameters, percentage change in serum TSH, Free thyroxine (FT4) and thyroglobulin (Tg) from baseline to Day 4 and appearance of microbubbles (hyperechoic marks (HEMs)) during treatment were compared between groups. To determine independent factors, a multivariate analysis was done by logistic regression analysis.Results: Baseline characteristics and treatment parameters were comparable between groups. However, on Day-4, group I had significantly lower serum TSH (0.49mIU/L vs. 0.84mIU/L, p = 0.011) and higher FT4 (22.11 pmol/L vs. 18.47 pmol/L, p = 0.008) than group II. The percentage change in TSH, FT4 and Tg were significantly greater in group I (p = 0.002, p = 0.009 and p = 0.001 respectively). The proportion of HEMs observed during treatment was also significantly higher in group I (42.69% vs. 31.72%, p = 0.030). Among the significant factors, the percentage change in FT4 was the only independent factor for 12-month shrinkage (OR = 1.018, 95%CI =1.003-1.032, p = 0.017).Conclusions: Percentage change in serum FT4 on post-treatment Day-4 was an independent blood parameter for the subsequent nodule shrinkage at 12 months. This finding could potentially facilitate the decision for earlier retreatment of treated nodules.

The current state and future perspectives of high intensity focused ultrasound (HIFU) ablation for benign thyroid nodules

High intensity focused ultrasound (HIFU) is a new thermoablation technique used to treat benign thyroid nodules. In this method, the ultrasound beam passes through the patient's skin and focuses very precisely on the target lesion at a distance far from the source of ultrasound generation, making HIFU the only truly non-invasive method of thermoablation developed to date. HIFU is therefore an attractive alternative to surgery and other thermoablative techniques. This review describes the principles of HIFU treatment, the selection of patients suitable for HIFU, the course and effects of treatment, and future perspectives.

The Efficacy and Safety of High-Intensity Focused Ultrasound (HIFU) Therapy for Benign Thyroid Nodules-A Single Center Experience from Singapore

BACKGROUND

High-intensity focused ultrasound (HIFU) is a recent noninvasive technique of treating thyroid nodules. Our study aims to investigate the efficacy and safety of HIFU in treating benign thyroid nodules.

METHODS

This is a retrospective analysis of consecutive patients who underwent HIFU of benign thyroid nodules at our institution from July 2017-2018. All procedures were performed by a single surgeon. Patients were evaluated immediately post-procedure, and at subsequent intervals of 1 week, 1 month, 3 months, and 6 months. The primary endpoint was thyroid nodule volume reduction at 6 months posttreatment. Secondary endpoints were post-procedure local complications.

RESULTS

Ten patients with 13 thyroid nodules were included. The median follow-up period was 426 days (range 238-573). Mean maximum diameter reduced from 2.6 cm (±0.8) pretreatment to 1.4 cm (±0.7, P < 0.05) 6 months posttreatment. Mean nodule volume reduced from 5.2 cm³ (±4.2) pretreatment to 1.5 cm³ (±1.3, P = 0.01) 6 months posttreatment. Mean volume reduction ratio (VRR) at 6 months posttreatment was 63.2% (±22.5, P < 0.05), with volume reduction of ≥50% in 10 of 13 (76.9%) nodules. Two nodules (15.4%) showed size increases from 4 months posttreatment. No patients experienced local skin burns or hematomas. Mean pain scores were 1.5 (±1.2) immediate post-procedure, 0.8 (±1.5) at 1 week, and 0.6 (±1.2) at 1 month post-procedure, respectively, with no reports of pain beyond 1 month. Only two (20.0%) patients had early, temporary posttreatment voice hoarseness.

CONCLUSION

Our study shows HIFU ablation to be efficacious and safe-with significant thyroid nodule volume reductions, and no significant or prolonged local complications.

Two-year outcomes of single-session high-intensity focused ultrasound (HIFU) treatment in persistent or relapsed Graves' disease

OBJECTIVE

To evaluate the longer-term disease relapse of ultrasound (US)-guided high-intensity focused ultrasound (HIFU) ablation as a treatment for persistent/relapsed Graves' disease (GD).

METHODS

After ethics approval, consecutive patients with persistent or relapsed GD who underwent bilateral US-guided HIFU ablation from 2016 to 2017 were retrospectively analyzed. Altogether, 75 patients received HIFU ablation of the central portion of the right and left thyroid lobes with areas near the trachea-esophageal groove and common carotid artery un-ablated. They were followed for 24 months or longer. Baseline thyrotropin (TSH), free T4, anti-thyroid autoantibodies, and TSH receptor (TSHR) antibody were checked. Primary outcome was the 24-month relapse rate. Relapse referred to hyperthyroidism (free T4 (FT4) > 23 pmol/L) afterwards. Variables associated with relapse were analyzed by binary logistic regression.

RESULTS

The cohort comprised mostly females (84.0%) with a mean age of 42.05 ± 10.74 years. The 24-month relapse rate was 41.3% with 31 patients suffering a relapse. No patient suffered from hypothyroidism. Three patients (4.0%) suffered from temporary vocal cord palsy but these injuries recovered spontaneously after 2 months. In univariate analysis, higher daily dose of carbimazole (OR = 1.125, 95% CI = 1.023-1.237, p = 0.015) and higher baseline TSHR level (OR = 1.085, 95% CI = 1.022-1.152, p = 0.007) were significant factors for disease relapse. In the multivariate analysis, higher baseline TSHR level was a significant independent factor for disease relapse within 24 months (OR = 1.079, 95% CI = 1.014-1.148, p = 0.016).

CONCLUSIONS

US-guided HIFU of the thyroid gland was a safe and relatively efficacious treatment in the longer term for patients with persistent or relapsed GD.

KEY POINTS

• US-guided HIFU ablation is relatively efficacious in the longer term. • US-guided HIFU ablation of the thyroid is safe. • Higher TSHR level may lead to higher disease relapse after treatment.

A propensity-matched analysis of clinical outcomes between open thyroid lobectomy and high-intensity focused ultrasound (HIFU) ablation of benign thyroid nodules

BACKGROUND

High-intensity focused ultrasound is a promising, nonoperative treatment for benign thyroid nodules. Our study aimed to compare treatment outcomes of single-session high-intensity focused ultrasound ablation with open lobectomy after propensity score matching.

METHODS

After propensity matching, we compared treatment-related morbidity, treatment time, duration of hospitalization, improvement in symptom score, cost, and acoustic parameters of consecutive patients who underwent high-intensity focused ultrasound ablation or lobectomy. All eligible patients completed the computerized, multidimensional voice program and Voice Handicap Index questionnaire before, and 3 and 6 months after treatment.

RESULTS

The matched cohort comprised 154 patients (77 in each group). Although treatment-related morbidity was comparable between the two groups (P = .368), treatment time (P <.001), duration of hospitalization (P <.001), and medical cost (P <.001) were less in the high-intensity focused ultrasound group. After high-intensity focused ultrasound ablation, the 6-month nodule shrinkage (mean ± SD) was 64% ± 26% and the 6-month symptom improvement score was comparable with lobectomy (P = .283). At 6 months, none of the acoustic parameters were changed from the baseline in both groups (P >.05), and the Voice Handicap Index questionnaire did not differ between the two groups (P >.05).

CONCLUSION

Despite having similar treatment-related morbidity and voice outcomes, there were possibly some advantages with high-intensity focused ultrasound during open lobectomy, including the avoidance of a neck scar, shorter treatment time and duration of hospitalization, and lower medical cost.

Role of second high-intensity focused ultrasound (HIFU) treatment for unsatisfactory benign thyroid nodules after first treatment

BACKGROUND

We aimed to assess the efficacy and safety of second high-intensity focused ultrasound (HIFU) ablation treatment in benign thyroid nodules that had failed to shrink by > 50% 6 months after the first treatment.

METHODS

Twenty-eight patients who did not achieve 50% volume reduction at 6 months after the first HIFU treatment underwent a second HIFU treatment. Nodule volume was measured on ultrasound at baseline, 3 months and 6 months. Extent of nodule shrinkage (by volume reduction ratio) (VRR) = [Baseline volume - volume at 6 months]/[Baseline volume] * 100. Treatment success was defined as VRR > 50%. Obstructive symptom score (by 0-10 visual analogue scale, VAS) was evaluated for 6 months after treatment.

RESULTS

No complications occurred after the second treatment. The mean 6-month VRR was 21.78 ± 16.87% with a median (range) of 16.16 (1.63-54.07)%. At 6 months, only two (7.1%) patients achieved treatment success, while nine (32.1%) patients had VRR < 10%. However, relative to baseline (3.96 ± 1.04), the mean VAS significantly improved at 3 and 6 months (2.96 ± 1.43, p<0.001 and 2.58 ± 1.39, p<0.001, respectively). There was a significant correlation between VRR and improvement in VAS score at 6 months (ρ=0.438, p=0.025). Greater nodule volume before the second treatment (OR=1.169, 95% CI=1.004-1.361, p=0.045) was a significant factor for greater VRR after the second treatment.

CONCLUSIONS

Although subjective obstructive symptoms continued to improve after the second treatment, the actual extent of nodule shrinkage was small. Larger-volume nodules tended to shrink more significantly than smaller-volume nodules in the second treatment.

KEY POINTS

• Second treatment resulted in small shrinkage in unsatisfactory nodules after first treatment. • Obstructive symptoms tended to continue to improve after second treatment. • Larger-size nodules tended to respond better in the second treatment.