3D ultrasound assisted laparoscopic liver surgery by visualization of blood vessels

Laparoscopic surgery remains a challenging procedure because visualization of the internal target organ cannot be achieved from the laparoscopic image. We have proposed a laparoscopic surgery support method relying on three-dimensional (3D) images reconstructed using a stereo laparoscope and a 3D ultrasound system. The aim of this study is to develop a visualization system providing depth information about blood vessels within the liver. The shape and depth information of blood vessels are then correctly superimposed on a 2D laparoscopic image on the basis following careful registration. The coordinates of the laparoscope and the ultrasound are registered by aligning the two 3D liver surface shapes obtained by a stereo laparoscope and an ultrasonic diagnostic equipment with a mechanically moved convex probe using multiple image processing techniques. Then, the shape and depth information within the liver are calculated, and color-coded blood vessel depth information is superimposed on the original 2D laparoscopic image. In a phantom experiment, the registered 3D images were the mean squared error (MSE) of 5.89 ± 3.11 mm. The 2D laparoscopic image was superimposed the color-coded depth of the blood vessels segmented from the 3D ultrasonic data. The calculation of depth information had the MSE of 1.88 ± 1.40 mm.