Data processing techniques for serial EIT spectroscopy images: a review of some preliminary results

Electrical impedance tomography (EIT) in applications related to lung and ventilation: a review of experimental and clinical activities

This review article is a summary of the publications dealing with the pulmonary applications of electrical impedance tomography (EIT). Original papers on EIT lung imaging published over 15 years are analysed and several aspects of the performed EIT measurements summarized. Information on the type of the EIT device and electrodes used, the studied transverse thoracic planes, the data acquisition rate, the number of studied animals, normal subjects or patients, the kind of lung pathology, the performed ventilatory manoeuvres and other interventions, as well as the applied reference techniques, is given. The type of the generated pulmonary EIT images and the quantitative analysis of the EIT data are described. Finally, the major results achieved are presented, followed by an analysis of the perspectives of EIT in clinical applications. A comparative analysis of the EIT hardware and the quality of the evaluation tools was not performed.

A comparison of neonatal and adult lung impedances derived from EIT images

An objective method of extracting respiratory data from lung images is presented, together with a technique for automatically generating regions of interest delineating the anterior and posterior regions of the lungs. The method is used to extract data on the change in lung impedance with frequency, and on calculated Cole parameters, from 19 normal neonates (gestational age 32 to 42 weeks) and 8 normal adults (age 21 to 82 years). A comparison of the impedance properties of neonatal and adult lungs was made. The variation of lung impedance with frequency in neonates, as derived from EIT images, is significantly different from that found for adults. The implications for a model of the electrical impedance of lung tissue are discussed.

Multifrequency and parametric EIT images of neonatal lungs

The aims of the study were to investigate the problems involved in making multifrequency EIT measurements on neonates and to compare the images obtained with the results from a group of normal adults. The Sheffield electrical impedance tomographic spectroscopy (EITS) system acquires multifrequency data using a set of eight drive and eight receive electrodes. EITS measurements were made on an inhomogeneous group of 10 neonates admitted to the special care baby unit for observation and feeding. R/S, characteristic frequency, RC and SC parameters were generated using the Cole equation. Comparisons of the parameters were made with data collected from normal adults in another study. We have shown that it is possible to obtain EITS parametric images of neonatal lungs and that there are some differences in Cole parameters between the adult and neonatal groups.