3D Monitoring of the Intraoperative Brainshift by Means of Photogrammetry

This paper presents the preliminary results of applying multi image photogrammetric techniques for the three-dimensional monitoring of the intraoperative brainshift. The brainshift is the motion of cerebral structures occurring in neurosurgery after the craniotomy (opening of the skull in order to access the brain for surgical repair). The causes of this effect are mainly the changes of pressure and loss of cerebrospinal liquid. The phenomenon of brainshift can influence negatively the planning and execution of neurosurgical intervention. A research project at the Clinic of Neuroradiology and Neurosurgery of the Medical University of Innsbruck (Austria) aims at the quantification of the intraoperative brainshift by means of photogrammetry. The goals of the project are: (i) the development of a multi-image photogrammetric system for the quantitative monitoring of intraoperative brainshift by means of 3D measurements performed on the surface of the brain during neurosurgery after craniotomy, (ii) transformation of the pre-operative performed MR and CT datasets in function of the quantified intra-operative brainshift. This paper presents the proposed multi-image photogrammetric system, as well as, the first results achieved. in collaboration with Hometrica Consulting, for the automatic 3D measurement and tracking of selected points on the surface of the brain.