RICERCA ITALIANA     

TEBAM: study, development and physiological-clinical validation of a multi-modal methodology for the 3D "True Electrical Brain Activity Mapping" in normal and pathological subjects

Università degli Studi di Trieste

Abstract

The aim of this Research Project is to study and develop an advanced tool, TEBAM (True Electrical Brain Activity Mapping), based on the multimodal integration of Magnetic Resonance (MR) neuroimaging methods with neurophysiological data, in particular with electroencephalographic data, to allow true 3D electrical brain activity mapping in a very refined spatio-temporal scale. This tool will be able to be used be used either in normal conditions (on healthy subjects) or in critical conditions as in the presence of morphologic brain pathologies (expansive morphological lesions altering functionally and anatomically the encephalon).
This research will be carried out by three Research Units, characterized by complementary scientific backgrounds in bioengineering and radiological fields, the fusion of which is essential for the achievement of the research objectives. The three research units will collaborate for the adjustment of three-dimensional anatomo-functional models based on new RM multimodal methods, in particular DT-MRI and RM methods alternative to those currently in use for Functional Imaging, to be integrated with neurophysiological three-dimensional data to obtain the above cited tool. These models will be able to include the individual tissue conductivity characteristics with their electric anisotropy and with the unpredictable additional variations caused by the presence of a morphologic brain pathology. This project has in fact among its objectives the >>>

Principal Investigator

Paolo INCHINGOLO Università degli Studi di TRIESTE

Research Objectives

The objective of this Research Project is to develop an advanced tool, TEBAM (True Electrical Brain Activity Mapping), for an investigation approach with multimodal non invasive techniques, integrating different kinds of neurophysiological and neuroimaging data, allowing true 3D electrical brain activity mapping in a refined temporal scale.
This tool will be able to be used be used either in normal conditions (on healthy subjects) or in critical conditions as in the presence of morphologic brain pathologies (expansive morphological lesions altering functionally and anatomically the encephalon). This tool will be based on a three-dimensional anatomo-functional model of the head based on the multimodal integration of Magnetic Resonance methods. Such model will be able to include the individual tissue conductivity characteristics with their electric anisotropy and with the unpredictable additional variations caused by the presence of a morphologic brain pathology. This requirement is based on the fact that the knowledge of the electrical conductivity properties of the tissues is a key point to find the relationship between electromagnetic fields generated by a tissue, e.g., the measure of electroencephalographic potentials, and the neural sources the activation of which generates the measured electroencephalographic signals, as source mapping accuracy heavily depends on the accuracy of the conductivity values assigned to the tissues in the volume conductor head model >>>

First Results

On the basis of the results obtained during the first phase of the Project by the U-RADIOL-PI Unit about the new experimental solutions for the technologies of diffusion tensor imaging, the U-RADIO-FISIO-TS Unit will develop in collaboration with the U-BIOING-TS Unit an original method which will make it possible to obtain individual tissue conductivity data starting from DT-MRI imaging measurements. This innovative technique will allow the quantitative deduction of tissues' electrical conductivity tensor starting from water self-diffusion tensor, obtained from DT Magnetic Resonance Imaging measurements. The U-BIOING-TS Unit, after having defined by means of a simulation analysis the necessary characteristics ad the possible validity limits, will build basing on this result a numerical 3D phantom of the head (named "volume conductor head model") mimicking the real shape of the head and of its structures with the actual conductivity values of its tissues and eventually their anisotropy, even in the presence of morphologic pathologies in the brain. The fusion of the results achieved by the three Research Units during the first phase of this Project will allow to obtain an extremely precise and refined volume conductor head model for the 3D mapping of the sources of electrical brain activity performed starting from electroencephalographic measurements.At the end of the second phase of the Project, the realization of an advanced tool for true 3D electrical brain activity mapping >>>

Timescale

24 months

National and international background

Over the last decade tremendous progress has been made in the development of techniques and methods for producing macroscopic images of human brain activity. Optimal technology for the study of cerebral functionality in humans should be characterized by a very good spatial and temporal resolution, to be able to detect and localize even quick variations in cerebral activity (1). Nevertheless the State of the Art of technology imposes the following limits: a) high temporal resolution is a property typical only of some functional exams, like electroencephalography (EEG) and magnetoencephalography (MEG); b) high spatial resolution on the other side is a property of structural exams: it is very good for typical neuroimaging techniques like Computed Tomography (CT) and Magnetic Resonance Imaging (MRI); c) functional neuroimaging techniques exploring haematic perfusion and cerebral metabolism, like Positron Emission Tomography (PET), Single Photon Emission Computed Tomography (SPECT) and functional Magnetic Resonance (fMRI) only guarantee a low spatial resolution and a limited temporal resolution (1). Only by combining different structural (anatomical) and functional methods for brain exploration it is possible to obtain at the same time a high spatial and temporal resolution.
It must be also noted that functional neuroimaging techniques allow indirect visualization of the activity of groups of neurons through the correlated variations in haematic flux, metabolism and >>>