High-intensity focused ablation (HIFU) of single benign thyroid nodule rarely alters underlying thyroid function

Figures & data

Table 1. Baseline patient characteristics.

	N = 72
Age at treatment (years)	49.34 ± 11.60
Sex (male/female)	0/72
TSH (mIU/L)	1.37 ± 1.05
Free T4 (pmol/L)	16.2 ± 2.5
WHO grade at presentation
Grade 1b (palpable and visible when neck extended)	19 (26.4)
Grade 2 (visible when neck is in the normal position)	39 (54.2)
Grade 3 (visible from distance)	14 (19.4)
Side of nodule (right/left/Isthmus)	33/37/2
Location within lobe (upper third/middle third/lower third)	9/20/43
Nodule size by USG
Width (cm)	2.6 ± 1.2
Length (cm)	3.5 ± 1.6
Thickness (cm)	2.1 ± 1.0
Volume (mL)^#	18.1 ± 13.3
Proportion of solidity (%) by USG
70–85	21 (29.2)
>85	51 (70.8)
Distance from skin to centre of the nodule (mm)	18.2 ± 7.3

Data expressed either as number (%) or mean ± SD.

USG: ultrasonography; WHO: World Health Organisation; TSH:  thyroid stimulating hormone.

# Volume = (width × length × thickness) × (π/6) where π was taken as 3.1416.

Table 2. Treatment parameters and efficacy over 6 months.

	N = 72
Treatment parameters (range)
Total energy delivered (KJ)	14.30 ± 7.39
Total duration of treatment (min)	67.27 ± 27.48
Size/volume of index nodule (mL)
Baseline	18.10 ± 13.32
3 months	5.27 ± 6.58
6 months	2.78 ± 2.66
Volume reduction from baseline
3 months (%)	49.23 ± 24.03
6 months (%)	63.09 ± 18.89
WHO nodule grade at 6 months
Grade 1a (palpable but not visible when neck is extended)	25 (34.7)
Grade 1b (palpable and visible when neck extended)	23 (31.9)
Grade 2 (visible when neck is in the normal position)	18 (25.0)
Grade 3 (visible from distance)	6 (8.3)
Symptom improvement score at 6 months
0 (no improvement)	5 (6.9)
1 (slight improvement)	14 (19.4)
2 (moderate improvement)	30 (41.7)
3 (significant improvement)	23 (31.9)

Data expressed either as number (%) or mean ± SD.

WHO:  World Health Organisation.

Table 3. Patients who had one lobe surgically removed before high intensity focused ultrasound (HIFU) ablation.

Patient no.	Ablated nodule volume	Total thyroid volume	Ablation volume ratio (%)*	Serum TSH (mIU/L)				Serum FT4 (pmol/L)
				Base	1 week	3 months	6 months	Base	1 week	3 months	6 months
1	12.83	20.05	64.00	4.62	2.70	5.97	6.70	15.0	17.0	11.0	11.0
2	21.31	81.52	26.14	0.51	0.08	0.55	1.10	16.0	16.0	15.5	14.0
3	9.77	16.69	58.54	0.72	0.09	0.87	1.10	16.0	18.0	17.5	18.0
4	12.00	25.25	48.00	1.41	0.35	1.90	1.38	13.0	15.0	15.0	17.0
5	11.90	20.90	56.93	1.39	1.90	2.14	1.93	14.0	19.0	18.0	18.0
6	19.92	79.17	24.00	0.49	0.74	0.89	0.98	18.0	17.0	19.0	16.0
7	17.60	110.00	16.00	1.31	0.32	1.19	2.24	17.0	18.0	16.0	17.0
8	8.12	19.01	42.72	0.80	0.31	1.94	1.31	16.0	19.0	18.0	19.0
9	5.82	12.09	48.12	3.38	2.70	3.41	3.19	14.0	17.5	16.0	15.0
10	12.62	38.85	32.41	2.10	0.08	1.12	1.24	14.0	16.0	17.0	17.0
11	8.38	24.55	34.12	1.12	0.09	1.29	1.63	16.0	18.5	17.0	18.0
12	7.75	12.66	61.25	1.83	0.18	1.19	1.21	13.0	19.5	15.0	16.0
13	11.20	19.85	56.43	0.85	0.91	1.27	2.35	17.0	20.0	16.0	14.0
14	1.68	3.90	43.19	2.89	0.77	2.19	4.10	14.0	21.0	18.0	12.0
15	16.76	32.70	51.24	3.12	2.13	3.56	3.24	15.0	16.0	15.0	14.0
16	14.68	34.84	42.15	1.31	1.28	1.36	1.38	17.0	19.0	17.0	19.0
17	8.47	15.04	56.31	0.90	1.52	0.38	1.83	18.0	23.0	19.0	17.0

Bold font signifies outside the normal biochemical reference range.

M: male; F: female; TSH: thyroid stimulating hormone (normal: 0.35–4.78 mIU/L); FT4: free thyroxine (normal: 12–21 pmol/L).

* Ablation volume ratio (%) = [(Ablated nodule volume/total thyroid volume)/(total thyroid volume)] × 100.

Table 4. First 6 months changes in thyroid function following one-sided HIFU ablation between patients with ablated nodule volume <30% of total glandular volume and with ablated nodule volume ≥30% of total glandular volume.

Ablation volume ratio*	Baseline		1 week		3 months		6 months
	TSH (mIU/L)	FT4 (pmol/L)	TSH (mIU/L)	FT4 (pmol/L)	TSH (mIU/L)	FT4 (pmol/L)	TSH (mIU/L)	FT4 (pmol/L)
<30% (n = 39)	0.89 (0.43–3.70)	16.0 (12.0–23.0)	0.50 (0.05–2.70)	17.0 (12.0–21.0)	1.19 (0.32–3.40)	17.0 (13.0–23.0)	1.10 (0.67–3.40)	17.0 (12.0–23.0)
≥30% (n = 33)	1.39 (0.61–4.62)	16.0 (13.0–22.0)	1.28 (0.05–2.70)^#	18.5 (13.0–23.0)^#	1.40 (0.32–5.97)	17.0 (11.0–21.0)	1.40 (0.32–6.70)	17.0 (11.0–23.0)

TSH: thyroid stimulating hormone (normal: 0.35–4.78 mIU/L); FT4: free thyroxine (normal: 12–21 pmol/L).

* Ablation volume ratio (%) = [(Ablated nodule volume/total thyroid volume)/(total thyroid volume)] × 100.

Wilcoxon signed-rank test was used to compare different time points.

# p < 0.05 relative to baseline.

Figure 1. Boxplots of the serum TSH (mIU/L) between with an intact whole thyroid gland (no history of lobectomy) (group I, n = 55) and those with a history of lobectomy (group II, n = 17). Comparison by the Wilcoxon signed-rank test.

Figure 2. Boxplots of serum free T4 (pmol/L) between with an intact whole thyroid gland (no history of lobectomy) (group I, n = 55) and those with a history of lobectomy (group II, n = 17). Comparison by the Wilcoxon signed-rank test.