Neuronavigation

A 3D model of the patient's head is rendered from MRI images of his skull. This model is then co-registered to the head of the patient in the operating theater. During surgery a registered probe (like a pen) can be used to virtually show a point in the patient's brain on a screen next to the operating table. This is only a virtual estimation of the true surgical situation, and subject to two important errors: Firstly the co-registration of the patients head to the MRI image is associated with a certain degree of uncertainty (up to 5mm over the course of surgery). Secondly the geometry of the brain changes as soon as the skull is opened and parts of the tumor have been resected. Mostly the brain is sinking a few millimeters into the skull and surrounding brain regions, that have been compressed by the tumor, extend after parts of the tumor have been removed. Thus the tumor and the localization of important brain areas doesn’t resemble the preoperative images any more, leading to an increasing inaccuracy as the operation goes on.