Symmetry difference electrical impedance tomography-a novel modality for anomaly detection

Area of Science:

• Medical Imaging
• Electrical Impedance Tomography
• Biomedical Engineering

Background:

• Traditional electrical impedance tomography (EIT) is effective for dynamic changes but less suited for static conditions.
• Many biological systems, like the human head, exhibit inherent symmetry.
• Detecting subtle, static abnormalities in symmetrical regions poses a challenge for existing imaging modalities.

Purpose of the Study:

• To introduce and validate a novel EIT technique, termed symmetry difference EIT, for imaging symmetrical regions.
• To demonstrate the theoretical basis and experimental feasibility of symmetry difference EIT.
• To assess the utility of symmetry difference EIT in detecting unilateral lesions in a symmetrical anatomical context.

Main Methods:

• Developed the theoretical framework for symmetry difference EIT, leveraging inherent symmetry in the region of interest.
• Employed computer simulations using hemispherical and anatomically accurate finite element models (FEMs) of the human head.
• Validated the technique through tank experiments with phantom lesions to assess real-world applicability.

Main Results:

• Symmetry difference EIT successfully detects deviations from normal symmetry caused by lesions.
• Detection efficacy correlates with lesion size and distance from the plane of symmetry.
• Quantitative metrics and imaging provide robust identification of abnormalities, distinguishing between hemorrhagic and ischemic lesions.

Conclusions:

• Symmetry difference EIT is a valuable imaging modality for symmetrical regions, particularly in static or quasi-static scenarios.
• This technique offers an alternative to time-difference EIT when changes over time are not the primary focus.
• The method's ability to detect abnormalities without requiring a baseline 'normal' scan enhances its applicability.