Systematic errors in multi-frequency EIT

Systematic errors have been measured with a multi-frequency data-collection system operating between 10.24 and 81.92 kHz. The errors were present even though a conventional background measurement on a uniform saline phantom had already been subtracted. Errors due to changes in transimpedance between...

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Bibliographic Details
Published in:Physiological measurement 2000-02, Vol.21 (1), p.111-118, Article 111
Main Authors: Schlappa, J, Annese, E, Griffiths, H
Format: Article
Language:English
Subjects:
Biometry
Electric Impedance
Evaluation Studies as Topic
Humans
Image Processing, Computer-Assisted
Phantoms, Imaging
Tomography - methods
Tomography - statistics & numerical data
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Summary:Systematic errors have been measured with a multi-frequency data-collection system operating between 10.24 and 81.92 kHz. The errors were present even though a conventional background measurement on a uniform saline phantom had already been subtracted. Errors due to changes in transimpedance between the calibration and the tissue measurements, cable movement and electrode-skin contact impedance were simulated giving a total systematic error estimate equivalent to a 9% change in tissue conductivity. It was shown that more than 89% of the image was above the total error magnitude, indicating that most of the image revealed true changes in tissue conductivity. In three human subjects, the largest conductivity changes were in two regions, located posteriorly on either side of the midline, and were interpreted as due to the erector spinae muscles. These regions showed increases in conductivity of 73-104%. Identification of other anatomical features was difficult because of the poor spatial resolution of the images.
ISSN:0967-3334
1361-6579
DOI:10.1088/0967-3334/21/1/314