Neurosurgical Guidance Using the Stereo Microscope

Many neuro- and ENT surgical procedures are performed using the operating microscope. Conventionally, the surgeon cannot accurately relate information from preoperative radiological images to the appearance of the surgical field. We propose that the best way do this is to superimpose image derived data upon the operative scene. We create a model of relevant structures (e.g. tumor volume, blood vessels and nerves) from multimodality preoperative images. By calibrating microscope optics, registering the patient in-theatre to image coordinates, and tracking the microscope intra-operatively, we can generate stereo projections of the 3D model and project them into the microscope eyepieces, allowing critical structures to be overlayed on the operative scene in the correct position. We have completed initial evaluation with a head phantom, and are about to start clinical evaluation on patients. With the head phantom a theoretical accuracy of 4.6mm was calculated and the observed accuracy ranged from 2mm to 5mm.