Registration of 4D ultrasound images and its applications

The image registration of a set of images obtained at different stages of diagnosis, treatment, and evaluation is important for assessment of the therapeutic effect and changes in lesions over time in order to determine an effective treatment policy. Image-registration studies have been conducted in the fields of CT, MR, and positron emission tomography (PET). However, few studies have been reported on the registration of ultrasound images, although it is the most widely used diagnostic imaging devices for circulatory system and abdomen. In recent years, 4D ultrasound imaging systems have been developed that observe and record 3D volume data by scanning 2D ultrasound images electrically or mechanically. 4D systems are strongly expected to facilitate the registration of ultrasound images obtained at the various stages of the diagnostic processes. In this paper, we introduce registration of pre-operative, intra-operative, and post-operative images with the help of an improved registration method, surgical assistance by sequential registration of 4D volume data during surgery, and the development of 3D panoramic volume by the automatic registration of successive 3D volume data. (author)