**5. Navigation**

*Recent Advances in Laparoscopic Surgery*

**4.2 MRI compatible robot**

experiment by live porcine model.

*(Left) Master console (right) patient site of the teleoperation robot.*

signal. So even if the whole system is in a room like da Vinci, they are teleoperation robot in nature. In the case of long distance between operator site and patient site, delay in the signal transmission is not negligible. Therefore, fast transmission lines are chosen and employed. Marescaux et al. demonstrated telesurgery experiment on human patient between US and France [50]. We also have also successfully carried out animal telesurgery experiments several times between Japan and Korea, Japan and Thailand by using our own robot system (**Figure 12**) [51, 52]. In this study, we have employed relatively low cost ISDN line and low latency CODEC technology.

Anatomy identification is sometimes difficult during laparoscopic surgery. If surgeon can see vessel, nerve, and lesion under the organ surface, it will be strong merit for safety and quality of the operation. For this purpose, we used intraoperative open bore type MRI for real-time image acquisition and developed a laparoscopic surgical robot which can be placed inside the MRI gantry (**Figure 13**) [53]. As MRI has strong magnetic field, no magnetic metal such as stainless steel cannot be used. Our robot was made of mainly engineering plastic and titanium alloy. Also, we chose ultrasonic motors instead of magnetic motors. The system consists of two forceps and a camera. Additionally, needle insertion device can be attached. The surgeon console display shows the camera view, pre-operative MR image, and intraoperative real-time MR image. We have successfully demonstrated animal

**102**

**Figure 13.**

**Figure 12.**

*MRI image-guided surgical system, reprinted by permission from Springer Nature: Springer Nature [53].*

Navigation in surgery includes various techniques. In brain and ENT surgery where the organ deformation are relatively small, the navigation system which detects the real-time position of the instrument in the preoperative threedimensional image by using optical position sensors is often used. In laparoscopic surgery, as the organ movement is large, such precise position detection is not required. But sometimes surgeon requires to refer to the segmented preoperative image during the procedure in order to confirm anatomical structure. The problem was that it is very difficult to compare current two-dimensional camera image and preoperative three-dimensional image. In order to solve this problem, we have developed real-time viewer software and sensor system especially for da Vinci partial nephrectomy (**Figure 14**) [54, 55]. This system detects the robot camera angle by position sensor mounted to the da Vinci arm by our own attachment (because da Vinci does not allow to output such data). According to the camera angle, the system computes corresponding view in the three-dimensional preoperative image and displays at the small sub-display under the main display. By this navigation system, the surgeon can see the preoperative image in the same angle of current camera image. We found it very useful, and it is clinically used every time in our hospital.

**Figure 14.** *Navigation system for da Vinci surgery.*
