Influence factors and nomogram for volume reduction rate in benign thyroid nodule after thermal ablation

Figures & data

Figure 1. Flow chart of patients’ inclusion and exclusion criteria.

Table 1. The variables included in logistic regression model and definition.

Variables	Definition
Gender	Female/male
Age	Age (years)
Volume	Volume (cm^3) = abc × π/6
Boundary	Clear/unclear
Morphology	Regular shaped/irregular shaped
Echogenicity	Hypoechoic: the solid component of nodules has lower echogenicity compared with the surrounding thyroid gland. Isoechoic: the solid component of nodules has similar echogenicity compared with surrounding thyroid gland. Hyperechoic: the solid component of nodules has higher echogenicity compared with surrounding thyroid gland.
Component of nodules	Solid nodules: the nodule is entirely composed of solid tissue. Solid dominant nodules: the solid component account for more than 80% of nodules. Cystic-solid nodules: the solid component account for more than 20% but less than 80% of nodules. Cystic dominant nodules: the nodules have solid component but the solid component account for less than 20% of nodules.
Calcification	Yes: the nodules with any kind of calcification. No
Enhancement degree	Hyper-enhancement: the peak enhancement degree of nodules is higher than surrounding thyroid gland. Nohyper-enhancement: the peak enhancement degree of nodules is lower than or similar to surrounding thyroid gland.
Enhancement uniformity	Homogeneous/heterogeneous
Enhancement mode	Overall: the contrast agent fills the nodules as a whole. Centripetal: the contrast agent fills the nodules from periphery to central area. Eccentric: the contrast agent fill the nodules from periphery to central area.
Enhancement defect	Yes: there is some area without contrast agent perfusion in the solid thyroid nodules in contrast-enhanced ultrasound. No
Ring enhancement	Yes: there is a circular enhancement area surrounding the nodules. No
Equipment of ablation	Microwave/radiofrequency
Energy of ablation	Energy of ablation (J/mm^3) = Watt (W) × duration of ablation(s)/1000 × volume of nodules (cm^3)

Table 2. Demographic and clinical information of patients.

Variables	Total (238)	VRR ≥75.0% (145)	VRR <75.0% (93)	p
Gender (n)
Female	189	119	70	.206
Male	49	26	23
Age (years)	48.5 ± 13.5	49.5 ± 13.4	47.1 ± 13.6	.295
Volume (cm^3)	12.6 ± 12.7	12.2 ± 12.4	13.3 ± 13.3	.666
Boundary (n)
Clear	198	128	70	.014*
Unclear	40	17	23
Morphology (n)
Regular shaped	209	132	77	.058
Irregular shaped	29	13	16
Echogenicity (n)
Hypoechoic	65	51	14	<.001*
Isoechoic	97	84	13
Hyperechoic	76	10	66
Component (n)
Solid	88	51	37	.002*
Solid dominant	71	37	34
Cystic-solid	32	17	15
Cystic dominant	47	40	7
Calcification (n)
Yes	24	7	17	<.001*
No	214	138	76
Enhancement degree (n)
Hyper-enhancement	163	110	53	.002*
No hyper-enhancement	75	35	40
Enhancement uniformity (n)
Homogeneous	157	110	47	<.001*
Heterogeneous	81	35	46
Enhancement mode (n)
Overall	187	117	70	.590
Centripetal	32	18	14
Eccentric	19	10	9
Enhancement defect (n)
Yes	44	18	26	.003*
No	194	127	67
Ring enhancement (n)
Yes	111	94	17	<.001*
No	127	51	76
Technique of ablation (n)
Microwave	114	79	35	.011*
Radiofrequency	124	66	58
Energy of ablation (J/mm^3)	1.7 ± 0.9	1.5 ± 0.9	2.0 ± 0.9	<.001*

VRR: volume reduction rate.

*Statistically significant difference (p < .05).

Figure 2. Forest plot of multivariate logistic regression for volume reduction rate ≥75.0% in benign thyroid nodules after thermal ablation.

Figure 3. A nomogram to predict the probability of volume reduction rate ≥75.0% in benign thyroid nodules after thermal ablation at 12-month follow-up.

Figure 4. (a) The receiver-operating characteristics curve of the nomogram, the AUC was 0.926. (b) The calibration curve of the nomogram. (c) The decision curve analysis (DCA) of the nomogram.

Data availability statement

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