Realization of Real-Time MR Image Guided Surgery Combined with High-Resolution 3D Image Navigation

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Real-time MR images, which are acquired every 2-3 seconds, are quite useful for image-guided surgery, but their image resolution and contrast are not always satisfactory because of the limited acquisition time. We planed to combine high resolution preoperative 3D image data with real-time MR images for surgical navigation. First, we prepared a program on the MR system to send acquired real time images and the information, of the hand-piece position for image plane control continuously. Navigation software, 3D Slicer, was obtained from Harvard, was installed in an independent computer and was customized for our purpose, We could successfully reconstruct reformatted images in the same and perpendicular planes as the real-time MR images from preoperative 3D image data and send these images to the surgeons inside immediately. Although the needle position had to be recognized in the real-time images, the reformatted images showed the target more clearly than the real-time. This system has already been used in 50 cases of microwave ablation for liver tumors and 10 neurosurgical cases. The reformatted images could also show the surrounding structures of the target, such as large vessels, and made the procedure safer. For the real-time MR images, Tl-weighted images are usually used, but any images with different contrasts, such as T2-weighte images or Gd-enhanced images could be combined as the preoperative 3D volume data. In the microwave thermocoagulation therapy of liver tumors, punctures and ablations are repeated many times. We added "FootPrinting" function in this software in order to record the individual football-shaped coagulation areas in the 3D space. This function made the procedure more accurate and easy. This system is now used in all the procedures.