Factors influencing thermal injury to skin and abdominal wall structures in HIFU ablation of uterine fibroids

Figures & data

Figure 1. Pre-operative and post-operative MRI. T2-weighted images of a 51-year-old woman with uterine fibroids but no abdominal wall scar. (A) Axial view before HIFU treatment, indicating no abnormal signals in the abdominal wall; (B) Hyperintense signals on the axial view after HIFU treatment (indicated by the arrowhead); T2-weighted images and contrast-enhanced MRI images of a 41-year-old case with uterine fibroids and an abdominal wall scar. (C) Sagittal view before HIFU treatment, indicating no abnormal signals in the abdominal wall; (D) Hyperintense signals in the sagittal view after HIFU treatment (indicated by the arrowhead); (E) Sagittal contrast-enhanced image before HIFU treatment; (F) Sagittal contrast-enhanced image after HIFU treatment, uterine fibroids located in the anterior wall and posterior wall of the uterus were almost completely ablated with non-perfusion area in the fibroids (indicated by the arrowhead).

Table 1. Patient baseline characteristics.

Variable	The damaged group	The non-damaged group
No. of patients	151	741
Age (years)	40.3 ± 7.0	39.0 ± 6.4
Thickness of abdominal wall (mm)	32.4 ± 8.5	28.4 ± 7.5
BMI	23.7 ± 3.0	22.2 ± 2.6
Volume of fibroids (cm^3)	128.0 ± 121.0	108.8 ± 105.0
Fibroid ventral side to skin (mm)	42.5 ± 16.2	41.0 ± 19.0
Abdominal scars (with scar or not) yes/no	48/103	167/574

BMI: body mass index.

Table 2. Treatment results of HIFU for patients.

Variable	The damaged group	The non-damaged group
Sonication time/hour (s/h)	778.3 ± 205.1	691.9 ± 209.3
Sonication time (s)	1673.8 ± 761.4	1102.1 ± 710.7
Total energy (KJ)	686.7 ± 413.9	442.7 ± 421.2
NPV ratio (%)	76.8 ± 20.5	80.2 ± 17.1

NPV: non-perfused volume.

Table 3. Univariable logistic regression analysis of variables associated with thermal damage of the abdominal wall structures.

Variable	p	OR	95%CI
Thickness of abdominal wall (mm)	0.000	1.570	1.329–1.854
BMI	0.000	2.097	1.575–2.745
Abdominal scar	0.016	1.602	1.092–2.350
Volume of fibroids (cm^3)	0.011	1.229	1.048–1.441
Fibroid ventral side to skin (mm)	0.046	1.175	1.003–1.377
Sonication time/hour (s/h)	0.000	1.523	1.287–1.801
Sonication time (s)	0.000	2.123	1.764–2.556
Total energy (KJ)	0.000	2.180	1.807–2.630

OR: odd ratio; CI: confidence index; BMI: body mass index.

Table 4. Multiple logistic regression analysis of variables associated with thermal damage of the abdominal wall structures.

Variable	p	OR	95%CI
Total energy (KJ)	0.000	2.228	1.831–2.712
Thickness of abdominal wall (mm)	0.000	1.562	1.313–1.857
Abdominal scar	0.019	1.639	1.085–2.477

OR: odd ratio; CI: confidence index.

Table 5. Post-operative adverse reactions of patients [n (%)].

	The damaged group (n = 151)		The non-damaged group (n = 741)
Items	SIR class A	SIR class B	SIR class A	SIR class B	p
Lower abdominal pain^a	72 (47.7)	0	272 (36.7)	0	0.012
Sciatic/buttock pain	23 (15.2)	0	152 (20.5)	3 (0.4)	0.111
Vaginal bleeding and discharge	21 (13.9)	2 (1.32)	120 (16.20)	7 (0.9)	0.568
Lower limb paresthaesia	7 (4.6)	3 (2.0)	21 (2.8)	12 (1.6)	0.257
Urinary retention	0	1 (0.7)	0	2 (0.3)	0.427
Fever	1 (0.7)	0	5 (0.7)	0	1.000
Haematuria	2 (1.3)	0	1 (0.1)	2 (0.3)	0.201

^a Significant difference was observed between the two groups, p < 0.05.