Non-contrast enhanced MRI for assessment of uterine fibroids’ early response to ultrasound-guided high-intensity focused ultrasound thermal ablation

•DWI doesn’t require a contrast agent and can be completed within minutes.•A complete high-signal ring was observed in most patients using DWI.•The complete high-signal ring area was consistent with the non-perfused area.•DWI can effectively evaluate ablation rate for most patients with uterine fibroids. 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. In total, 508 patients with 598 fibroids 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. 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); however, this difference was statistically significant compared with the incomplete high-signal ring volume on DWI (P 0.75, P