Non-contrast Enhanced MRI For Assessment Of Uterine Fibroids' Early Response To Ultrasound-guided High-intensity Focused Ultrasound Thermal Ablation

Purpose: To examine non-contrast enhanced MRI value to evaluate necrotic area and ablation rate of uterine fibroids after high-intensity focused ultrasound(HIFU)thermal ablation.Method: In total,508 patients with 598 ?broids who underwent HIFU treatment were enrolled.Contrast-enhanced MRI(CE-MRI)with diffusion-weighted imaging(DWI)were performed before treatment and within two days post-treatment.DWI signal performance of post-operative fibroids was observed;apparent diffusion coefficient(ADC)and DWI signal values pre-and post-operation were measured.The volume of post-operative DWI signal change area and post-contrast enhanced fibroid necrosis area were compared.Results: Average ADC and DWI signal values before HIFU treatment were higher than those post-operation;the difference was statistically significant before and after ablation(P < 0.05).After HIFU,78.09%(467 /598)of DWI showed complete regular or irregular high-signal rings and21.91%(131 / 598)showed incomplete high-signal rings.No significant difference was noted between the complete high-signal ring volume on DWI and the non-enhanced volume(P > 0.05);however,this difference was statistically significant compared with the incomplete high-signal ring volume on DWI(P < 0.05).Two doctors had good agreements on evaluating the morphology of high-signal rings(? > 0.75,P < 0.05).Conclusions: Combined with pre-operative T2 WI and post-operative DWI,non-contrast enhanced MRI can effectively evaluate ablation rate for most patients with uterine fibroids.