Direct estimation of Cole parameters in multifrequency EIT using a regularized Gauss-Newton method

Bernhard Brandstätter, Karl Hollaus, Helmut Hutten, Michael Mayer, Robert Merwa, Hermann Scharfetter

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)


A major drawback of electrical impedance tomography is the poor quality of the conductivity images, i.e., the low spatial resolution as well as large errors in the reconstructed conductivity values. The main reason is the necessity for regularization of the ill-conditioned inverse problem which results in excessive spatial low-pass filtering. A novel regularization method (SMORR (spectral modelling regularized reconstructor)) is proposed, which is based on the inclusion of spectral a priori information in the form of appropriate tissue models (e.g. Cole models). This approach reduces the ill-posedness of the inverse problem, when multifrequency data are available. An additional advantage is the direct reconstruction of the (physiological) tissue parameters of interest instead of the conductivities. SMORR was compared with posterior fitting of a Cole model to the conductivity spectra obtained with a classical iterative reconstruction scheme at various frequencies. SMORR performed significantly better than the reference method concerning robustness against noise in the data.

Original languageEnglish
Pages (from-to)437-448
Number of pages12
JournalPhysiological Measurement
Issue number2
Publication statusPublished - May 2003


  • Gauss-Newton
  • Multifrequency EIT
  • Regularization
  • Artifacts
  • Algorithms
  • Models, Biological
  • Humans
  • Sensitivity and Specificity
  • Electric Impedance
  • Tomography/methods


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