Harmonic Analysis for the Separation of Perfusion and Respiration in Electrical Impedance Tomography

Electrical Impedance Tomography (EIT) is mainly used to display information about the respiration of a patient. However, also cardiac-related signals are present, and, although they have small amplitude, they can be distinguished by their frequencies. In this contribution, we report a method based on harmonic analysis to separate respiration and perfusion. These are described by a summation of amplitude-modulated signals at different frequencies. We report the mathematical background of the method and its application on the global impedance and, finally, show how it is possible to create frequency-related images highlighting either the respiration or the perfusion inside an EIT video.