Use of a volumetric target for image-guided surgery.

A VIRTUAL REALITY system has been devised to superimpose a computer-generated rendering of a volumetric target to be surgically approached or resected on a real-time video image of the surgical field. A stereotactic frame is used to register the image from the video camera with the image of the target volume for accurate localization. The volumetric target is obtained from preoperative imaging studies and can be modified to adjust the intended line of resection or to avoid eloquent vascular or neural tissue. The computer-generated image is updated throughout surgery to visualize only that part of the tumor under resection so the surgeon may guide the resection along the border of the mass or intended preplanned line of resection. To date, 74 intracranial tumor resections have been performed under video virtual reality guidance. Postoperative scanning corresponds in every case with preoperative planning. This system is also designed to be adapted to frameless guidance, which can be further enhanced by the incorporation of an audible tone to signal the relationship of the tip of the resection instrument to the line of resection.