Three-dimensional electrical impedance tomography of human brain activity

Area of Science:

• Neuroimaging
• Biomedical Engineering
• Electrical Engineering

Background:

• Brain activity alters regional cerebral blood flow and volume, changing local tissue impedance.
• Electrical Impedance Tomography (EIT) offers a noninvasive method to image internal impedance variations.
• Existing EIT technology is fast, portable, and inexpensive but has limited spatial resolution.

Purpose of the Study:

• To investigate the feasibility of using EIT with scalp electrodes for neuroimaging human brain function.
• To assess the detectability and reproducibility of impedance changes associated with neural activity.
• To develop and apply a novel 3-D reconstruction algorithm for EIT brain imaging.

Main Methods:

• EIT system optimized for brain function recording used with scalp electrodes.
• 39 adult human subjects underwent visual, somatosensory, or motor stimulation.
• A novel 3-D reconstruction algorithm was employed to generate impedance images.

Main Results:

• Reproducible impedance changes of approximately 0.5% were observed in 51 out of 52 recordings.
• Significant impedance changes localized to the appropriate cortical regions were identified in 19 datasets.
• The study demonstrated the potential for recording impedance changes from the human brain using scalp electrodes.

Conclusions:

• Scalp-recorded impedance changes during brain activity are detectable and reproducible.
• EIT shows potential as a novel, noninvasive neuroimaging technology.
• Further refinement is needed to reduce spatial noise in EIT images for improved resolution.