Déjà vue in the operating room-three-dimensional volumetric imaging

The objectives for microsurgical image-guidance in intracranial procedures are different from the entry-trajectory-target paradigm for stereotactic purposes. From a neurosurgical series of 125 patients with various intracranial pathologies having received surgery that was aided by image guidance, we have derived three basic principles for the successful application of neuronavigation in daily routine: (1) Less is more. Redundant anatomical information-basically all information that is unrelated to surgical landmarks in a particular case-should be omitted from the guiding images. (2) The approach and the surgical target should be visible in a single 3D guiding image. To this end, gradual tuning of the opacity of outer tissue layers in images is the method of choice to outline the in relation to the anatomy that needs to be dissected by the surgeon in order to arrive at the target. (3) All available information on functional tissue properties should be added to the guiding image. Preservation of function has become the single most important demand for neurosurgical procedures. Results of fMRI, DTI and other validated functional studies can readily be added to the structural image. Adhering to these principles may truly enhance the capacities of the surgeon who not only experiences a déjà vue of the individual surgical anatomy when looking through the operating microscope but can also base his intra-operative decisions on invisible functional landmarks.