[Clinical application of three-dimensional ultrasound imaging as intraoperative navigation for liver surgery]

Intraoperative hepatic ultrasonography provides a great deal of information about tumor location and vascular anatomy in the liver, and is an indispensable procedure for hepatic resection. However, an accurate three-dimensional understanding of ultrasound (US) images depends on the operator's skill and experience, as the original display is two dimensional. We developed a new three-dimensional US (3D-US) image processing method by application of the intensity projection method to US. The minimum and maximum intensity projection can display the arrangement of blood vessels (hepatic veins and portal veins) and hyperechoic regions, respectively. The intensity projection from several points of view can reconstruct 3D imaging by cine-display. Moving a probe manually, images are taken and processed on a real-time basis (in about 10 seconds). 3D-US was used in 24 patients undergoing hepatic resection, and allowed easy visualization of the tumors and vascular anatomy. It is considered to be an efficient and safe navigation system in liver surgery.