Author
   Adler A. Guardo R. Berthiaume Y.
Institution
   Inst. de Genie Biomed., Ecole Polytech. de Montreal, Que., Canada.
Title
   Impedance imaging of lung ventilation: do we need to account for chest
   expansion?
Source
   Proceedings of the 16th Annual International Conference of the IEEE
   Engineering in Medicine and Biology Society. Engineering Advances: New
   Opportunities for Biomedical Engineers (Cat. No.94CH3474-4). IEEE. Part
   vol.1, 1994, pp.534-5 vol.1. New York, NY, USA.
   Conference Information
   Proceedings of 16th Annual International Conference of the IEEE
   Engineering in Medicine and Biology Society. Baltimore, MD, USA. 3-6 Nov.
   1994.
Abstract
   Electrical impedance tomography uses surface electrical measurements to
   image changes in the conductivity distribution within a medium. When used
   to measure lung ventilation, however, measurements depend both on
   conductivity changes in the thorax and on rib cage movement. Given that
   current reconstruction techniques assume that only conductivity changes
   are present, certain errors are introduced. We use a finite element model
   to calculate the effect of chest expansion on the reconstructed
   conductivity images. Results indicate that thorax expansion accounts for
   approximately 20 percent of the reconstructed image amplitude, and its
   contribution is relatively independent of inspiration depth. We propose
   that chest expansion can contribute significantly to the conductivity
   images of lung ventilation, and should be taken into account in
   interpreting these images.