Electrical Impedance Tomography

This short chapter describes the physics of an imaging method known as electrical impedance tomography (EIT), which involves reconstructing an image where contrast is due to variations in the ability of the tissue to allow the passage of (usually alternating) electrical current. The physiological origins of such variations are reviewed, and it is discussed how these might reveal information of diagnostic value. The underlying mathematics of EIT image reconstruction is presented, including an indication of how assumptions inherent in various practical approaches can limit their performance in practice. Alternative EIT data acquisition protocols are briefly examined, and the instrumentation developed for medical applications of EIT is described. The chapter concludes with a brief summary of current and likely future diagnostic applications.