Position estimation of moving liver lesion based on registration between 2D ultrasound and 4D MR images

Abstract

The interest for the registration between 2D ultrasound (US) and preoperative CT or MR images has been growing for US-guided diagnosis, intervention, and surgery. In our previous study, we proposed a real-time and automatic registration system between two images of the liver without any help of positioning sensors. We have confirmed that the system can provide an accurate and reliable registration performance, if sufficient features are included in a current US image. In this paper, we propose a robust position estimation system of a moving liver lesion based on the previously proposed registration system. The system indirectly but reliably estimates the lesion position by registering a US image including sufficient features to 4D MR images, even if the US image does not include the target lesion. The proposed system is evaluated on three clinical datasets, through both qualitative and quantitative evaluations. Experimental results show that the registration error for target lesions is less than 5 mm on average, which is considered acceptable for many clinical applications.

Position tracking of moving liver lesion based on real‐time registration between 2D ultrasound and 3D preoperative images

“…(19), we convert the coordinates of the prestored positions of target lesion in all 3D preoperative images of different respiratory phases to the US image coordinates so that they can be used for real-time positioning. 14…”

“…However, if none of the real-time 2D US image planes which include a lesion have features that can be used for registering to preoperative images, we then have to choose a 2D US image plane which does not include a lesion, but which does have better features for registration. The position of the target lesion can then be determined using the registered preoperative image and its displacement from the lesion, 14 which has been predetermined in the intraoperative preparatory stage described in Sec. 2.B.2.…”

“…12,13 In this paper, we propose a purely image-based registration system for the US-guided intervention of the liver, based on our previous works. [13][14][15] The proposed system provides real-time registration between intraoperative 2D US and successive multiple 3D preoperative MR/CT images without using an external tracking device. In the system, we first generate a sequence of 3D preoperative images along the respiratory phase (that is, a 4D preoperative image), based on the nonrigid registration of several 3D preoperative images.…”