Fusion of Multiple-angles Intraoperative US Images and Pretreatment MR Images for USgHIFU Treatment of Uterine Fibroid: Retrospective Evaluation Based on Clinical Dataset.

High-intensity focused ultrasound (HIFU) has been widely used for treatment of uterine fibroids. However, due to the limited resolution of ultrasound image in deep organs, the guidance of ultrasound-guided HIFU (USgHIFU) treatment greatly depends on clinicians' experience in US image. To address this issue, fusion of intraoperative US images and pretreatment MR images has been proposed. Contour segmentation and multiple-angles 2D US images combination are performed to obtain 3D points along the contour of uterus. Iterative closest point (ICP) algorithm based on prior knowledge is used to register these point sets. MR and US images of six treated patients are used for evaluation. The mean distance error (MDE) of our algorithm is 1.71±0.59 mm, and the average running time is 0.18 s. The results have verified the feasibility of fusion of MR images and US images for USgHIFU guidance. In addition, this method may be also potential for post-ablation evaluation with follow-up MR images.