A stereoscope for image-guided surgery

A method of image guidance for neurosurgery using the surgeon's binocular depth perception is described. Magnetic resonance volume acquisitions and surface rendering software were used to produce stereoscopic pairs of images of the surface of the heads of patients with brain tumours. Stereoscopic pairs of the surface rendering of the tumour were also produced. The two pairs of images were colour-coded and combined into one pair of 35-mm slides. A stereoscopic viewer was constructed to allow simultaneous viewing of the pair of slides and the patient's head. Registration was achieved by moving the stereoscope in space until the virtual images of the rendered surface of the head coincided with the real head. The stereoscope was then locked in position and the virtual image of the tumour was projected 'into' the patient's head to allow the surgeon to locate the tumour. The instrument was used in six cases. A lateral accuracy of 10-15 mm was achieved and a depth accuracy of 5-10 mm.