Head modeling for realistic electrical brain activity mapping identification of a multimodal neuroimaging protocol.

Realistic electrical brain activity mapping implies reconstructing and visualizing sources of electrical brain activity within the specific patient's head. This requires the assumption of a precise and realistic volume conductor model of the specific subject's head, i.e., a 3-D representation of the head's electrical properties in terms of shape and electrical conductivities. Source reconstruction accuracy is influenced by errors committed in head modeling. Clinical images, MRI and CT, are used to identify the head structures to be included in the volume conductor head model. Modeling accuracy mainly relies on the correct image-based identification of head structures, characterized by different electrical conductivities, to be included as separate compartments in the model. This paper analyzes the imaging protocols used in clinical practice to define the most suitable procedures for identification of the various head structures necessary to build an accurate head model also in the presence of morphologic brain pathologies. Furthermore, tissues anisotropy is discussed and identified as well. With this work we have identified a protocol for the acquisition of multimodal patient's imaging data for realistic electrical brain activity mapping purposes, able to account for pathological conditions and for head tissues anisotropy.