3D simulation of EIT for monitoring impedance variations within the human head

• Published in: Physiological measurement Vol. 21; no. 1; p. 119
• Main Authors: Towers, C M, McCann, H, Wang, M, Beatty, P C, Pomfrett, C J, Beck, M S
• Format: Journal Article
• Language: English
• Published: England 01-02-2000
• Subjects: Acoustic Stimulation; Carotid Arteries - physiology; Cerebrovascular Circulation; Computer Simulation; Electric Impedance; Head; Humans; Models, Anatomic; Models, Biological; Sensitivity and Specificity; Tomography - methods; Tomography - statistics & numerical data
• ISSN: 0967-3334
• DOI: 10.1088/0967-3334/21/1/315

A preliminary analysis is presented concerning the use of EIT for detecting impedance inhomogeneities within the human brain. The work to date is centred around the monitoring of two distinct impedance variations: those associated with the application of a carotid clamp during surgery and changes caused by the redistribution of blood flow during auditory stimuli. Using the commercially available Ansoft Maxwell package, a 3D finite element model of the human head has been developed to solve the forward problem. The model is hemispherical in shape and comprises regions of brain, cerebrospinal fluid, skull and skin and includes 16 scalp electrodes each of area 1 cm2. Results from simulations using the model suggest that an EIT system, incorporating diametric current excitation, would require a voltage measurement sensitivity of 100-120 dB in order to detect the impedance variations in the above cases.