Microwave ablation for papillary thyroid cancer located in the thyroid isthmus: a preliminary study

Figures & data

Figure 1. Flow chart of patient selection.

Figure 2. A 31-year-old woman with papillary thyroid cancer in the isthmus of the thyroid was treated with microwave ablation (MWA). (A) Before MWA, ultrasonography (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 (arrowheads) was used to protect the trachea surrounding the tumor (arrows); (D) US showed a hyperechoic pattern in the tumor (arrows) during ablation; (E), after MWA, CEUS showed no enhancement (arrows) in the tumor area; and (F) on day 1 after MWA, US showed a hypoechoic ablation zone (arrows).

Table 1. Demographic characteristics of the isthmic PTC patients included in this study (n = 34).

Variables	Total
Age (years)*	43 ± 11 (27–74)
Female	26 (76.5)
Male	8 (23.5)
Follow-up (months)*	17 ± 9 (8–50)
Ablation time (s)*	110 ± 45 (32–180)
Volume for hydrodissection (ml)	51 ± 10 (35–67)
BRAF V600E mutation
Positive	28 (82.4)
Negative	6 (17.6)
Hashimoto’s thyroiditis
Yes	5 (85.3)
No	29 (14.7)
Pre-MWA CEUS
Hyper	9 (26.5)
Iso	4 (11.8)
Hypo	21 (61.7)

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

Table 2. Indicators of thyroid function before MWA and at each follow-up time-point after MWA.

Follow-up time	T3 (ng/ml)	p Value	fT4 (ng/dl)	p Value	TSH (uIU/ml)	p Value
Before MWA (n = 34)	1.11 ± 0.18	NA	1.28 ± 0.15	NA	1.79 ± 1.29	NA
After MWA
1-month (n = 34)	1.11 ± 0.20	0.89	1.28 ± 0.17	0.93	1.62 ± 1.35	0.25
3-month (n = 34)	1.14 ± 0.22	0.24	1.32 ± 0.18	0.09	1.61 ± 1.32	0.06
6-month (n = 34)	1.12 ± 0.19	0.68	1.29 ± 0.19	0.69	1.69 ± 1.30	0.18

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 3. Indicators of parathyroid function before MWA and at each follow-up time-point after MWA.

Follow-up time	Calcium (mmol/L)	p Value	iPTH(pg/ml)	p Value
Before MWA (n = 34)	2.23 ± 0.16	NA	45 ± 18	NA
After MWA
1-month (n = 34)	2.26 ± 0.21	0.46	49 ± 17	0.48
3-month (n = 34)	2.30 ± 0.19	0.08	47 ± 16	0.69
6-month (n = 34)	2.24 ± 0.17	0.68	54 ± 17	0.09

p Value: after MWA (1, 3, or 6 months) vs. before MWA. iPTH: intact parathyroid hormone. NA, not applicable.

Table 4. Tumor size (maximum diameter and volume) before MWA and at each follow-up time-point after MWA.

Follow-up time	Maximum diameter (mm)	p Value	Volume (mm^3)	p Value
Before MWA (n = 34)	6.0 ± 1.9	NA	87.4 ± 74.9	NA
After MWA
1-month (n = 34)	9.9 ± 1.9	<0.001*	269.6 ± 103.1	<0.001*
3-month (n = 34)	7.4 ± 1.3	<0.001*	147.5 ± 64.2	<0.001*
6-month (n = 34)	5.4 ± 2.0	0.04	69.7 ± 46.8	<0.001
9-month (n = 31)	3.7 ± 3.1	<0.001	47.9 ± 47.7	<0.001
12-month (n = 22)	1.3 ± 2.5	<0.001	16.9 ± 33.3	<0.001
18-month (n = 13)	0.4 ± 1.4	0.001	2.4 ± 8.6	0.001

p Value: after MWA (1, 3, 6, 9, 12, or 18 months) vs. before MWA. *After MWA value is greater than before MWA value. NA, not applicable.