Incorporation of data revealing the 3-D structure of the vasculature of a patient is clinically significant in that, in addition to determining the coordinates of targets of interest, their locations could be the approached safely without puncturing blood vessels. This is critical, for example, during the implantation of depth electrodes for the recording of EEG signals and during the resection of tumours. We routinely employ two modalities, stereoscopic DSA and MRA, that allow 3-D visualization of the vasculature.