GREIT: A unified approach to 2D linear EIT reconstruction of lung images

Andy Adler, John H. Arnold, Richard Bayford, Andrea Borsic, Brian Brown, Paul Dixon, Theo J.C. Faes, Inéz Frerichs, Hervé Gagnon, Yvo Gärber, Bartłomiej Grychtol, Günter Hahn, William R.B. Lionheart, Anjum Malik, Robert P. Patterson, Janet Stocks, Andrew Tizzard, Norbert Weiler, Gerhard K. Wolf

Research output: Contribution to journalArticlepeer-review

481 Scopus citations


Electrical impedance tomography (EIT) is an attractive method for clinically monitoring patients during mechanical ventilation, because it can provide a non-invasive continuous image of pulmonary impedance which indicates the distribution of ventilation. However, most clinical and physiological research in lung EIT is done using older and proprietary algorithms; this is an obstacle to interpretation of EIT images because the reconstructed images are not well characterized. To address this issue, we develop a consensus linear reconstruction algorithm for lung EIT, called GREIT (Graz consensus Reconstruction algorithm for EIT). This paper describes the unified approach to linear image reconstruction developed for GREIT. The framework for the linear reconstruction algorithm consists of (1) detailed finite element models of a representative adult and neonatal thorax, (2) consensus on the performance figures of merit for EIT image reconstruction and (3) a systematic approach to optimize a linear reconstruction matrix to desired performance measures. Consensus figures of merit, in order of importance, are (a) uniform amplitude response, (b) small and uniform position error, (c) small ringing artefacts, (d) uniform resolution, (e) limited shape deformation and (f) high resolution. Such figures of merit must be attained while maintaining small noise amplification and small sensitivity to electrode and boundary movement. This approach represents the consensus of a large and representative group of experts in EIT algorithm design and clinical applications for pulmonary monitoring. All software and data to implement and test the algorithm have been made available under an open source license which allows free research and commercial use.

Original languageEnglish (US)
Pages (from-to)S35-S55
JournalPhysiological Measurement
Issue number6
StatePublished - 2009


  • Electrical impedance tomography
  • Image reconstruction
  • Lung physiology


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