Sensitivity maps for low-contrast perturbations within conducting background in magnetic induction tomography

Hermann Scharfetter*, Pere Riu, Marcos Populo, Javier Rosell

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Magnetic induction tomography (MIT) is a contactless method for mapping the electrical conductivity of tissue by measuring the perturbation of an alternating magnetic field with appropriate receiver coils. Reconstruction algorithms so far suggested for biomedical applications are based on weighted backprojection, hence requiring tube-shaped zones of sensitivity between excitation coils and receiving coils, the sensitivity being essentially zero outside this 'projection beam'. This condition is met for conducting perturbations in empty space and for some special configurations of insulators in saline. In biological structures, however, perturbations with low conductivity contrast are embedded into a bulk conductor. The respective sensitivity distribution was investigated and quantified theoretically and experimentally by displacing a conducting (agar, 8 S m-1) and an insulating sphere within a saline tank (4 S m-1). In contrast to the case in the empty space the sensitivity is not confined to a tube but even increases outside the 'projection beam'. The difference can be explained by the interaction of bulk currents with the perturbing object. This effect invalidates backprojection and hence the solution of the complete inverse eddy-current problem is suggested.

Original languageEnglish
Pages (from-to)195-202
Number of pages8
JournalPhysiological Measurement
Issue number1
Publication statusPublished - 27 Feb 2002


  • Backprojection
  • Low contrast objects
  • Magnetic induction tomography
  • Sensitivity distribution

ASJC Scopus subject areas

  • Biophysics
  • Physiology
  • Biomedical Engineering
  • Physiology (medical)

Fields of Expertise

  • Human- & Biotechnology

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