Measuring lung resistivity using electrical impedance tomography

Abstract

We propose the use of electrical impedance tomography (EIT) imaging techniques in the measurement of lung resistivity for detection and monitoring of apnea and edema. In EIT, we inject currents into a subject using multiple electrodes and measure boundary voltages to reconstruct a cross-sectional image of internal resistivity distribution. We found that a simplified, therefore fast, version of the impedance imaging method can be used for detection and monitoring of apnea and edema. We have showed the feasibility of this method through computer simulations and human experiments. We speculate that the EIT imaging technique will be more reliable than the current impedance apnea monitoring method, since we are monitoring the change of internal lung resistivity. However, more study is required to verify that this method performs better in the presence of motion artifact than the conventional two-electrode impedance apnea monitoring method. Future work should include experiments which carefully simulate different kinds of motion artifacts.

Estimation of Respiration Rate from Three-Dimensional Acceleration Data Based on Body Sensor Network

“…As the gold standard, the capnograph device was routinely used in hospital and critical care centers to monitor patients' respiratory status. 4 Other well-accepted respiratory monitoring techniques and devices are respiratory inductive plethysmograph (RIP) 5 , electrical impedance tomography 6 , thermistors for airflow measurements 7 , piezoelectric transducers, and micro-electromechanical systems (MEMS) accelerometers. Empowered by body sensor network (BSN) technology these methods became more easily to deploy while being less obtrusive to patients.…”

Generation of anisotropic-smoothness regularization filters for EIT

“…The matrix ( is the number of observations, and is the number of elements in which the conductivity has been discretized) is decomposed as (5) where and are and orthonormal matrices and with . Given the decomposition, the mapping of a change in the conductivity can be expressed as (6) The ill posedness of the problem is shown by the singular values rapidly decaying to zero: there are certain changes in parallel to the higher singular vectors (SVs) that are strongly attenuated and would become unobservable in the presence of noise.…”

“…The second approach is that of incorporating structural prior information into the reconstruction process to estimate the unknown conductivity more closely [5]- [9]. By this means, it is possible to enhance the sharpness of the images when the prior information is matched by the actual experiment, as shown by Kaipio et al [10].…”

A simplified model of mammography geometry for breast cancer imaging with electrical impedance tomography

“…It was reported in [4]- [6] that the conductivity and the permittivity of the tumors differ significantly from the normal tissues. These studies suggest that EIT is a promising modality to image the breast for malignancies 1 . Electrical impedance imaging has been used clinically to screen for breast cancer using a commercial imaging device called T-SCAN [7].…”

“…Typically, currents are applied through electrodes placed on the body's surface and the resulting voltages are measured. Reconstruction algorithms are used to compute the distribution of the conductivity and permittivity inside the body from the current and voltage data measured at the electrodes [1] - [3].…”