A feasibility study of microwave ablation for papillary thyroid cancer close to the thyroid capsule

Figures & data

Figure 1. (A) Measurement of distance between PTC tumor to thyroid capsule 348 (double headed arrow); (B) PTC tumor abutted to thyroid capsule without CI.

Table 1. Inclusion and exclusion criteria for study designs.

	Inclusion criteria	Exclusion criteria
Age	From 20 to 80 years old	<20 or >80 years old
Pathological diagnosis	PTC diagnosed by FNA	Benign thyroid nodules or other malignant tumors
Number of PTC lesions	Unifocal PTC	Multifocal PTC
Location	Abutted or adjacent to the thyroid capsule (≤2 mm)	Not close to the thyroid capsule (>2 mm)
Extra-thyroid extension	Without CI on US	Showed CI or mETE on US
LNM	Without	With
Distant metastasis	Without	With
Follow-up time after MWA	>9 months	≤9 months

Figure 2. Flow chart of patient selection.

Table 2. Demographic characteristics of enrolled and excluded cases in this study.

Variables	Enrolled (n = 106)	Excluded (n = 69)	p-Value
Age (years)	44.39 ± 11.13	44.51 ± 11.68	1.00
Sex(M/F)	19/87	10/59	0.68
Tumor stage
T1a/T1b	89/17	60/9	0.67
Nodule diameter (cm)	0.77 ± 0.35	0.85 ± 0.50	0.38
Nodule volume (ml)	0.20 ± 0.30	0.35 ± 0.56	0.15
Ablation time (s)	102.90 ± 63.41	117.94 ± 52.32	0.23

M: male; F: female. Except for sex (M/F), T1a/T1b and p-values, data are reported as mean ± standard deviations.

Table 3. Demographic characteristics of patients with PTC close to capsule included in this study (n = 106).

Variables	Total
Volume for hydrodissection^a	43.21 ± 22.62 ml
Follow-up (months)^a	24.95 ± 10.56
Tumor location
Right lobe	55 (52%)
Left lobe	46 (43%)
Isthmus	5 (5%)
Relationship with thyroid capsule
Abutted	71 (67%)
Adjacent	35 (33%)
BRAF V600E mutation
Positive	88 (83%)
Negative	12 (11%)
Hashimoto’s thyroiditis
Yes	14 (13%)
No	92 (87%)
Pre-MWA CEUS
Hyper	34 (32%)
Iso	14 (13%)
Hypo	58 (55%)

Unless indicated otherwise, data are presented as frequencies (percentage). ^aData presented as mean ± standard deviation (range). CEUS, contrast-enhanced ultrasound.

Figure 3. A 33-year-old woman with papillary thyroid cancer close to the capsule was treated with microwave ablation (MWA). (A) pre-MWA, ultrasound (US) showed a hypoechoic target tumor (arrows); (B) before MWA, contrast-enhanced US (CEUS) showed a hypo-enhancement pattern in the artery phase (arrows); (C) the hydrodissection technique (triangles) was used to protect the trachea surrounding the tumor (arrows); (D) US showed a hyperechoic pattern in the tumor (arrows) during ablation; (E) post-MWA, CEUS showed no enhancement (arrows) in the tumor area; and (F) on 1 month post-MWA, US showed a hypoechoic ablation zone (arrows).

Figure 4. Changes in mean volume at each follow-up time point.

Figure 5. Changes in VRR at each follow-up time point.

Table 4. Indicators of thyroid function before MWA and after MWA.

Follow-up time	T3 (ng/ml)	p-Value	fT4 (ng/dl)	p-Value	TSH (uIU/ml)	p-Value
Before MWA (n = 106)	1.11 ± 0.22	NA	1.27 ± 0.13	NA	1.56 ± 0.65	NA
After MWA
1-month (n = 106)	1.22 ± 0.78	0.25	1.34 ± 0.22	0.07	1.60 ± 1.00	0.53
3-month (n = 106)	1.18 ± 0.32	0.22	1.74 ± 2.54	0.14	1.21 ± 1.07	0.05
6-month (n = 106)	1.12 ± 0.25	0.91	1.31 ± 0.13	0.06	1.30 ± 0.93	0.09

p-Value: after MWA (1, 3 or 6 months) vs. before MWA. T3: serum triiodothyronine; fT4: serum free thyroxine; TSH: serum thyrotropin. NA, not applicable.

Table 5. Tumor size (maximum diameter and volume) before MWA and at each follow-up time-point after MWA.

Follow-up time	Maximum diameter (cm)	p-Value	Volume (ml)	p-Value	Mean volume reduction rate	P versus last follow-up
Before MWA (n = 106)	0.77 ± 0.35	NA	0.20 ± 0.30	NA	NA	NA
After MWA
1-month (n = 106)	1.59 ± 0.47	0.000	1.08 ± 1.07	0.000	−9.85 ± 12.88	NA
3-month (n = 106)	1.27 ± 0.43	0.000	0.56 ± 0.62	0.000	−4.80 ± 8.87	0.000
6-month (n = 106)	0.96 ± 0.46	0.000	0.27 ± 0.33	0.003	−1.94 ± 6.11	0.000
9-month (n = 106)	0.66 ± 0.51	0.021	0.20 ± 0.60	0.011	−0.35 ± 2.78	0.000
12-month (n = 102)	0.40 ± 0.50	0.000	0.15 ± 0.26	0.000	0.22 ± 2.45	0.000
18-month (n = 88)	0.22 ± 0.41	0.000	0.08 ± 0.20	0.000	0.50 ± 2.02	0.000
24-month (n = 58)	0.20 ± 0.41	0.000	0.05 ± 0.15	0.000	0.61 ± 1.38	0.001
30-month (n = 37)	0.16 ± 0.43	0.000	0.04 ± 0.16	0.000	0.65 ± 1.36	0.123
36-month (n = 27)	0.15 ± 0.51	0.000	0.04 ± 0.18	0.001	0.86 ± 0.75	0.345
42-month (n = 14)	0.04 ± 0.13	0.001	0.03 ± 0.14	0.001	1.00 ± 0.02	0.180
48-month (n = 6)	0.00 ± 0.00	0.027	0.00 ± 0.00	0.028	1.00 ± 0.00	0.317

Data availability statement

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.