Microwave ablation versus radiofrequency ablation for primary hyperparathyroidism: a multicenter retrospective study

Figures & data

Figure 1. Images show ablation of pHPT nodule in a 47-year old female. (a) A hypoechoic pHPT nodule with sharp boundary (arrows) was behind superior right lobe of thyroid on US. (b) Uniform hyperenhancement of pHPT nodule (arrows) in arterial phase on CEUS. (c) Establishment of hydrodissection (blue arrow) around pHPT nodule (arrows). (d) Ablation procedure of pHPT nodule (arrows): hyperechoic area emerging inside nodule. (e) After ablation, non-enhancement area covered pHPT nodule (arrows) on CEUS. CEUS: contrast-enhanced US; pHPT: primary hyperparathyroidism; US: ultrasound.

Figure 2. Patient flowchart. MWA: microwave ablation; RFA: radiofrequency ablation; pHPT: primary hyperparathyroidism; PTX: parathyroidectomy.

Table 1. Baseline characteristics of patients underwent MWA and RFA.

Variables	MWA (77)	RFA (27)	p
Female (n)	52	18	.809
Age (years)	55.5 ± 16.4	58.9 ± 15.6	.351
Symptomatic (n)	45	15	.824
Bone pain (n)	19	5	.018
Renal stones (n)	22	6	1.000
Fatigue (n)	17	3	.267
Neurocognitive impairment (n)	2	2	.276
Hypercalcemic crisis (n)	2	2	.276
iPTH (pg/mL)	136.3 (91.9–401.8)	157.2 (91.1–671.1)	.034
Serum calcium (mmol/L)	2.71 ± 0.23	2.76 ± 0.28	.353
Serum phosphorus (mmol/L)	0.86 ± 0.18	0.87 ± 0.15	.746
Serum creatinine (umol/L)	60.1 (43.1–102.6)	66.2 (49.8–110.3)	.012
Urinary calcium (mmol/24 h)	7.04 ± 2.58	7.38 ± 4.67	.775
Total protein (g/L)	67.9 ± 6.4	67.6 ± 6.4	.845
Hemoglobin (g/L)	130.8 ± 17.0	132.2 ± 18.7	.733
Volume (mL)	0.327 (0.045–2.643)	0.528 (0.111–26.671)	.066
Maximum diameter (cm)	1.3 (0.6–3.0)	1.6 (0.8–5.0)	.238
Number (n)
1	69	26	.151
2	7	1	.677
3	1	0	1.000
Nodule location (superior)	30	4	.056
Nodule side (left)	50	12	.192

MWA: microwave ablation; RFA: radiofrequency ablation; iPTH: intact parathyroid hormone; ALP: alkaline phosphatase.

Table 2. Comparison of treatment parameter and clinical efficacy between MWA and RFA group.

Variables	MWA (77)	RFA (27)	p
Ablation time (s)	144 (67–312)	69 (33–297)	<.001
Energy (kJ)	4.83 ± 2.26	3.45 ± 2.63	.020
Active tip length (mm)	3	7	–
Applicator diameter (mm)	17 G	18 G	–
Isolation water (mL)	38 ± 15	41 ± 15	.370
Ablation cure rate	68/77	24/27	1.000
Recurrence pHPT	4/77	1/27	.448
Persistent pHPT	9/77	3/27	1.000
Complication	7	1	.677
Voice change	5	1	–
Hematoma	2	0	–
Side effects	17	8	.442
Headache	2	1	–
Fever	0	1	–
Numbness	15	6	–
Hypocalcemia	2	2	.276
Transient hypoparathyroidism	29	18	.013
Follow-up time (months)	18.7 (9.6–42.3)	12 (6.1–34.1)	.017

MWA: microwave ablation; RFA: radiofrequency ablation; pHPT: primary hyperparathyroidism.

Figure 3. Clinical cure rate curves. MWA: microwave ablation; RFA: radiofrequency ablation; M: month.

Table 3. The rates of achieving the normal level for iPTH, serum calcium and phosphorus in MWA group and RFA group after treatment.

	iPTH (pg/mL)			Calcium (mmol/L)			Phosphorus (mmol/L)
Follow-up time	MWA	RFA	p	MWA	RFA	p	MWA	RFA	p
Post-MWA (2H)	69/77 (89.6%)	25/27 (92.6%)	1.000	55/77 (71.4%)	17/27 (63%)	.470	44/77 (57.1%)	14/27 (51.9%)	.659
Post-MWA (1D)	70/76 (92.1%)	25/27 (92.6%)	1.000	65/76 (85.5%)	22/27 (81.5%)	.758	56/76 (73.7%)	17/27 (63.0%)	.329
Post-MWA (7D)	57/67 (85.1%)	21/24 (87.5%)	1.000	62/67 (92.5%)	22/24 (91.7%)	1.000	63/67 (94%)	22/24 (91.7%)	.652
Post-MWA (1M)	63/73 (86.3%)	23/27 (85.2%)	1.000	70/73 (95.8%)	26/27 (96.3%)	1.000	71/73 (97.3%)	26/27 (96.3%)	1.000
Post-MWA (3M)	59/65 (90.8%)	23/25 (92.0%)	1.000	60/65 (92.3%)	23/25 (92.0%)	1.000	63/65 (96.9%)	25/25 (100%)	1.000
Post-MWA (6M)	70/77 (90.9%)	24/27 (88.9%)	.717	68/77 (88.3%)	25/27 (92.6%)	.417	74/77 (96.1%)	26/27 (96.3%)	1.000

MWA: microwave ablation; RFA: radiofrequency ablation; iPTH: intact parathyroid hormone; H: hour; D: day; M: month.

Figure 4. The comparison of the serum iPTH, calcium, phosphorus, VRR between the RFA and MWA groups at each follow-up period. iPTH: intact parathyroid hormone; MWA: microwave ablation; RFA: radiofrequency ablation; H: hour; D: day; M: month; BA: before ablation; Ca: calcium; P: phosphorus; VRR: volume reduction rate. *p<.001 vs. before ablation.

Table 4. Analyses of prognostic factors for patients who did not received ablation cure.

Parameters	Odd ratio	p Value
Sex (male vs. female)	3.37 (0.98–11.56)	.053
Age (years)	0.98 (0.95–1.02)	.254
Ablation energy (kJ)	0.97 (0.75–1.25)	.809
Preoperative iPTH (pg/mL)	1.00 (1.00–1.01)	.612
Preoperative serum calcium (mmol/L)	0.38 (0.03–5.00)	.459
Maximum diameter (cm)	0.10 (0.02–0.54)	.007
Volume (mL)	0.34 (0.08–1.50)	.154
Nodule side (left vs. right)	1.61 (0.45–5.72)	.463
Nodule location (inferior vs. superior)	2.14 (0.62–7.41)	.229
Complication (yes vs. no)	0.41 (0.08–2.26)	.307
Treatment modality (MWA vs. RFA)	1.06 (0.27–4.24)	.936

MWA: microwave ablation; RFA: radiofrequency ablation; iPTH: intact parathyroid hormone.

Data in parentheses are 95% confidence intervals. The logistic regression model was used for the univariable analysis.