High-intensity focused ultrasound (HIFU) therapy for benign thyroid nodules: a 3-year retrospective multicenter follow-up study

Figures & data

Figure 1. Flowchart of the study.

Table 1. Description of patients’ and nodules’ characteristics.

Procedure	HIFU
Patients’ parameters	N = 65
Units
Center 1	14 (21.5)
Center 2	25 (38.5)
Center 3	16 (24.6)
Center 4	10 (15.4)
Age, years	51.1 ± 14.0
Gender (♀ / ♂)	56 (86.2) / 9 (13.8)
Cervical complaint (pressure symptoms) before procedure	45 (69.2)
Aesthetic complaint before procedure	20 (30.8)
Biological thyroid status
TSH, µIU/mL	1.45 ± 0.75
FT4, ng/dL	2.61 ± 3.58
Anti-TPO Ab (+)	13 (20)
Anti-TG Ab (+)	3 (5)
Nodules’ parameters	N = 65
Nodule volume at baseline, mL	9.8 ± 10.3
Single (one nodule)	42 (64.6)
Multiple (multi-nodular gland)	23 (35.4)
Location
Right lobe	34 (52.3)
Left lobe	28 (43.1)
Isthmic	3 (4.6)
Structure
Solid	40 (62.5)
Spongiform	24 (37.5)
Echogenicity
Isoechoic	64 (98.5)
Mildly hypoechoic	1 (1.5)
Regular margins	65 (100)
Vascularization
Central	40 (61.5)
Peripheral	19 (29.2)
Mixt	6 (9.2)
TIRADS
2	0 (0)
3	64 (98.5)
4A	1 (1.5)
4B	0 (0)
5	0 (0)
Class II of Bethesda (FNAC)	65 (100)
Number of CNB	0 (0)
Number of procedure	65 (100)

Values expressed as number (No. [%]) and mean ± standard deviation (SD). HIFU: High-Intensity Focused Ultrasound. TI-RADS: Thyroid Imaging Reporting and Data System. FNAC: fine needle aspiration cytology. CNB: core needle biopsy. Anti-TPO Ab: thyroperoxydase auto-antibodies. Anti-TG Ab: anti-thyroglobulin antibodies.

Table 2. HIFU ablation parameters.

Procedure	HIFU
Parameters	N = 65
Duration of the procedure, minutes	45.8 ± 20.7
Sedation (Midazolam) (yes)	48 (73.8)
Analgesics per or post-HIFU(yes)	49 (75.4)
Pixel, numbers	25.9 ± 14.2
Planned volume, cm^3	1.9 ± 0.8
Treated pixels, numbers	23.9 ± 13.4
Treated volume, cm^3	1.9 ± 0.8
Planned energy, kJ	8.1 ± 2.7
Delivered energy, kJ	7.1 ± 3.1
Mean energy, J/pixel	290.5 ± 60.9
Output, Watts	38.4 ± 10.5

Values expressed as number (No. [%]) and mean ± standard deviation (SD). HIFU: High-Intensity Focused Ultrasound.

Figure 2. Nodule volume reduction from baseline. In brackets (): number of patients at each time of follow-up.

Table 3. Evaluation of volume reduction at each time of follow-up.

Groups	N	HIFU	Percentage of reduction
Nodule volume
6 weeks, mL	45	8.5 ± 10.4	−16.7% (−30.4 to −4.4)
3 months, mL	38	9.3 ± 10.5	−19.5% (−33.3 to −6.0)
6 months, mL	58	6.6 ± 7.94	−30.3% (−39.9 to −22.3)
12 months, mL	45	5.8 ± 7.98	−31.5% (−38.6 to −23.1)
24 months, mL	29	3.8 ± 1.71	−33.3% (−39.0 to −27.3)
36 months, mL	29	4.1 ± 1.89	−31.9% (−36.4 to −16.1)

Values expressed as number (No. [%]), mean ± standard deviation (SD) and percentage reduction expressed as median (IQR). N: number of nodule at each time. HIFU: High-Intensity Focused Ultrasound.

Table 4. Evaluation of the safety of the HIFU ablation.

Groups	HIFU N = 65
Patients’ parameters
Adverse events	53 (81.5)
Major	1 (1.5)
Horner’s syndrome	1 (1.5)
Transient recurrent laryngeal nerve palsy	0 (0)
Compressive hematoma	0 (0)
Sub-cutaneous abscess	0 (0)
Minor	52 (80)
Per or post procedure pain	49 (75.4)
Subcutaneous edema	3 (4.6)
Nodule rupture with conservative treatment	0 (0)
Benign hematoma	0 (0)
Thyroiditis (US)	0 (0)
Hyperthyroidism	0 (0)
Transient dysphonia	0 (0)
Other procedure during follow-up	26 (40)
Another alternative treatment (laser ablation)	18 (27.7)
Surgery	8 (12.3)

Values are expressed as number (%). HIFU: High-Intensity Focused Ultrasound.

Figure 3. HIFU procedure. (A) Diagram of the active head: focalization of ultrasound on a target zone guided by ultrasound imaging. (B) The treatment head is positioned in contact with the skin in front of the nodule. A laser beam (red circle) detects any movement of the patient and can stop the procedure (repositioning of the system). (C) Planning. The operator draws on the screen, the boundaries of the nodule, the skin the trachea and the carotid artery. The computer-controlled device will treat the target tissue, while preserving the surrounding tissues. (D) Software screen during treatment: on the left: Concentrated Interference Pattern. (E) Hyperechoic marks (whitish spots) correspond to a treated area.