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Spatial dependence of the phase in localized bioelectrical impedance analysis
C A Shiffman1, R Aaron, A Altman
1Department of Physics, Northeastern University, Boston, MA 02115, USA.
Physics in Medicine and Biology
|April 28, 2001
Summary
A new model explains thigh bioelectrical impedance analysis phase functions using realistic shapes and conductivity tensors. This finding relates phase changes to conductivity components in healthy and ill subjects.
Area of Science:
- Biophysics
- Medical Imaging
Background:
- Localized bioelectrical impedance analysis (BIA) reveals varied phase functions on thighs.
- These variations occur in both healthy and seriously ill individuals.
Purpose of the Study:
- To model the observed phase functions in thigh BIA.
- To relate phase function variations to underlying conductivity properties.
Main Methods:
- Developed a model combining realistic thigh geometry with homogeneous, axially symmetric conductivity tensors.
- Analyzed the relationship between the phase function theta(z) and conductivity components phi(r) and phi(z).
Main Results:
- The model successfully represents observed phase functions.
- A general relationship was found: d theta/d(z) < 0 when phi(r) > phi(z), and vice versa.
- Quantitative results are sensitive to current injection methods.
Conclusions:
- Thigh BIA phase variations can be explained by a model incorporating realistic anatomy and anisotropic conductivity.
- The relationship between phase changes and conductivity components provides insights into tissue electrical properties.