Indirect measurement of lung density and air volume from Electrical Impedance Tomography (EIT) data

  • B H Brown
  • P Milnes
  • G H Mills
Conference paper
Part of the IFMBE Proceedings book series (IFMBE, volume 14)

Abstract

This paper describes new methods for determining lung density and air volume from an indirect measurement of the electrical resistivity of the lungs. Resistivity, in Ωm, was found by fitting measured Electrical Impedance Tomography (EIT) data to a Finite Difference model of the thorax. This part of the technique has already been described in the literature for neonatal lungs. Using the method now described lung density can also be determined by comparison of the resistivity of the lungs, measured at a relatively high frequency, with values predicted from a published model of lung structure. Lung air volume can also be calculated from a knowledge of total lung weight and density. The new method was implemented on EIT data collected from eleven normal adult subjects, using eight electrodes placed in a single plane around the thorax. A mean lung density of 292 kg m−3 (SD 36 kg m−3) was obtained. Sources of error are discussed. It is concluded that absolute differences in lung water of more than 25% and changes over time of 10% or more should be detected using the current technology.

Keywords

Impedance Tomography Spectroscopy Lung Density 
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References

  1. 1.
    Barber D C, Brown B H and Freeston I L (1983), ‘Imaging Spatial distributions of resistivity using Applied Potential Tomography’ Electronics Letters, 19, 93–95.CrossRefGoogle Scholar
  2. 2.
    Brown B H and Barber D C (1982), ‘Applied Potential Tomography’-a new in-vivo medical imaging technique. Proc. of the HPA Annual Conference, Sep. 1982, Sheffield.Google Scholar
  3. 3.
    Holder D S (edit) 2005 Electrical Impedance Tomography — Methods, History and Applications, IoP Publishing, Bristol ISBN 0 7503 0952 0.Google Scholar
  4. 4.
    B H Brown, Tidy J, Boston K, Blackett A D, Smallwood R H and Sharp F, (2000), The relationship between tissue structure and imposed electrical current flow in cervical neoplasia, The Lancet, 355: 892–95.CrossRefGoogle Scholar
  5. 5.
    Gheorghiu M, Gersing E and Gheorgiu E, 1999, Quantitative analysis of impedance spectra of organs during ischemia, Ann. N Y Acad. Sc. 20,873, 65–71.CrossRefGoogle Scholar
  6. 6.
    Noble T J, Harris N D, Morice A H, Milnes P and Brown B H, 2000, Diuretic induced changes in lung water assessed by electrical impedance tomography, Physiol. Meas. 21, 155–163.CrossRefGoogle Scholar
  7. 7.
    Frerichs I, Hahn G, Schroder T and Hellige G, 1998, Electrical. Impedance Tomography in Monitoring Lung Injury, Intensive Care Medicine, 24(8) 829–36.CrossRefGoogle Scholar
  8. 8.
    Brown B H, Primhak R A, Smallwood R H, Milnes P, Narracott A J and Jackson M J, (2002), Neonatal lungs — can absolute lung resistivity be determined non-invasively?, Med. Biol. Eng. 40, 388–394.CrossRefGoogle Scholar
  9. 9.
    Brown B H, Primhak R A, Smallwood R H, Milnes P, Narracott A J and Jackson M J, (2002), Neonatal lungs — maturational changes in lung resistivity spectra, Med. Biol. Eng. 40,5, 506–511.CrossRefGoogle Scholar
  10. 10.
    Barber DC, Seagar AD, (1987), Fast reconstruction of resistance. images. Clinical Physics & Physiol. Measurement., 8(A) 47–54CrossRefGoogle Scholar
  11. 11.
    Kiber A, 1991 Determination of object boundary shape for Electrical Impedance Tomography, PhD Thesis, Univ. of Sheffield.Google Scholar
  12. 12.
    Nopp P, Harris N D, Zhao T-x and Brown B H, (1997) Model for the dielectric properties of human lung tissue against frequency and air content. Med, & Biol. Eng, & Comp. 35, 695–702.CrossRefGoogle Scholar
  13. 13.
    Boyd E (1962), in Altman and Dittmer (Eds), Growth, Including Reproduction and Morphological Development, Biological Handbooks, Federation of American Society for Experimental Biology, Washington 346–348.Google Scholar
  14. 14.
    ICRP (1975) ‘Report of the task group on reference man’. International Commission on Radiological Protection Publication 23, pp 159–173 and pp 343–347.Google Scholar
  15. 15.
    Nebuya s, Noshiro M, Yonemoto A, Tateno S, Brown B H, Smallwood R H and Milnes P, 2006, Study of the optimum level of electrode placement for the evaluation of absolute lung resistivity with the Mk3 EIT system, Physiol. Meas. 27,5, S129–137.CrossRefGoogle Scholar
  16. 16.
    Zubal G 2005 Model data kindly provided by Dr George Zubal, Web reference-http://noodle.med.yale.edu/zubal/.Google Scholar
  17. 17.
    Sartene R, Martinot-LaGarde P, Mathieu M, Vincent A, Goldman M and Durand G, (1990), Respiratory cross-sectional area-flux measurements of the human chest wall, J. Appl. Physiol. 68(4): 1605–1614.Google Scholar

Copyright information

© International Federation for Medical and Biological Engineering 2007

Authors and Affiliations

  • B H Brown
    • 1
  • P Milnes
    • 1
  • G H Mills
    • 2
  1. 1.Medical PhysicsSheffield UniversityUK
  2. 2.Intensive Care MedicineSheffield Teaching HospitalsSheffieldUK

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