MRI compatible manipulator with MRI-guided needle insertion support system

We developed a MRI compatible manipulator system operated under the use of preoperative / intraoperative MR images to realize RFA needle navigation for minimally invasive liver surgery inside an Open MRI gantry. This system has a capability to position a needle to a target inside the MRI gantry by integrating the real space, preoperative/intraoperative MR images and the manipulator coordinate systems with the optical three-dimensional tracking system. Positioning of puncture needle to target is shown in the followings. Puncture needle is positioned with the manipulator for target using preoperative MRI images. Intraoperative MR images including puncture needle and target are acquired by using MR fluoroscopy. Then surgeon inserts the puncture needle to the target. Needle follows the moving target using intraoperative MR images when object/organ is distorted by puncture. We also quantified the MRI compatibility of the manipulator based on MR images. The results showed that MR images have no distortion, and the SNR decreased by 1.2%. Thus the manipulator has high MRI compatibility and is drivable while acquiring MR images. The phantom experiments are conducted to evaluate the needle insertion accuracy, the system positioning and needle insertion accuracy was 0.8 mm±0.29 mm, when the phantom is distorted and the target was moved by puncture. As conclusion, our system is sufficiently accurate and therefore feasible for performing the device guidance inside MRI environment.