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

Objective: To investigate the factors which may cause thermal injury of abdominal wall structures in ultrasound-guided high-intensity focussed ultrasound (USgHIFU) ablation of uterine fibroids.

Method: A total of 892 patients with uterine fibroids diagnosed on contrast-enhanced magnetic resonance imaging (MRI) scans received HIFU ablation and follow-up MRI scanning. After therapy, thermal injury to the skin was assessed via measurement of skin redness, blisters, subcutaneous nodules and to the abdominal wall structures via measurement of signal intensity on T2-weighted MRI images. A total of 151 patients were assigned to the injury group, 741 patients were assigned to the non-injury group. The relationship between patient and treatment parameters and injury were analysed using univariate and multiple logistic regression analyses.

Results: Univariate logistic regression revealed that sonication time, sonication time per hour, total energy deposited, distance from uterine fibroid ventral side to skin, volume of uterine fibroids, abdominal wall scar, abdominal wall thickness and body mass index (BMI) all affected whether thermal injury occurred (p < 0.05). Subsequently, multiple logistic regression analysis revealed that total energy (p = 0.000, OR = 2.228, 95% CI 1.831-2.712), abdominal wall scar (p = 0.019, OR = 1.639, 95% CI 1.085-2.477) and abdominal wall thickness (p = 0.000, OR = 1.562, 95% CI 1.313-1.857) were significantly correlated with thermal injury.

Conclusion: Multiple logistic regression analysis revealed that abdominal wall thickness, total energy and abdominal wall scar were the most significant influencing factors that influenced minimal thermal injury of abdominal wall structures in USgHIFU ablation of uterine fibroids.