Relative influence of model assumptions and measurement procedures in the analysis of the MEG

  • J. W. H. Meijs
  • M. J. Peters
  • H. B. K. Boom
  • F. H. Lopes da Silva
Physiological Measurement


The relative influences of several model parameters and measurement setups on the MEG are studied quantitatively. The influences of the number of grid points of the flux transformer and the accuracy of the measurements are analysed using as criterion a relative difference measure (RDM). In a similar way, using the RDM, the influence of various models is evaluated. The volume conductor, i.e. the head, is described by three different compartment models: the first model consists of concentric spheres, the second of eccentric spheres optimally fitting the individual compartments of the head, and the third consists of realistically shaped compartments. The evaluation of the influence of the model of the source on the MEG is studied by taking either one single current dipole or a set of two current dipoles. The RDM described in the paper is shown to be a valuable measure in the quantitative analysis of MEGs.


Experimental accuracy Grid point density Magnetoencephalogram Source model Volume conductor model 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Abramowitz, M. andStegun, I. A. (1972)Handbook of mathematical functions. Dover Publ. Inc.Google Scholar
  2. Akima, H. (1978) A method of bivariate interpolation and smooth surface fitting for irregular distributed data points.ACM Trans. on Math. Software,4, 148–159.zbMATHCrossRefGoogle Scholar
  3. Cohen, D. andCuffin, B. N. (1983) Demonstration of useful differences between magnetoencephalogram and electroencephalogram.Electroenceph. Clin. Neurophysiol.,56, 38–51.CrossRefGoogle Scholar
  4. Cuffin, B. N. (1985) A comparison of moving dipole inverse solutions using EEG's and MEG's.IEEE Trans.,BME-32, 905–910.Google Scholar
  5. Grynszpan, F. andGeselowitz, D. B. (1973) Model studies of the magnetocardiogram.Biophys. J.,13, 911–925.CrossRefGoogle Scholar
  6. Lehmann, H. P. (1983) Signal processing. InBiomagnetism: an interdisciplinary approach.Williamson, S. J., Romani, G. L., Kaufman, L. andModena, I. (Eds.), Plenum Press, New York, London, 591–624.Google Scholar
  7. Lynn, M. S. andTimlake, W. P. (1968) The use of multiple deflations in the numerical solution of singular systems of equations with applications to potential theory.Siam. J. Numer. Anal.,5, 303–322.zbMATHMathSciNetCrossRefGoogle Scholar
  8. MacAulay, C. E., Stroink, G. andHoracek, B. M. (1985) Analyses of MCG spatial maps during the PR-interval.Med. & Biol. Eng. & Comput.,23, Suppl., Part 2, 1479–1480.Google Scholar
  9. Meijs, J. W. H., Peters, M. J. andvan Oosterom, A. (1985) Computation of MEGs and EEGs using a realistically shaped multi-compartment model of the head.,23, Suppl., Part 1, 36–37.Google Scholar
  10. Meijs, J. W. H., Bosch, F. G. C., Peters, M. J. andLopes da Silva, F. H. (1987a) On the magnetic field distribution generated by a dipolar current source situated in a realistically shaped compartment model of the head.Electroenceph. Clin. Neurophysiol.,66, 286–298.CrossRefGoogle Scholar
  11. Meijs, J. W. H., Boom, H. B. K., Peters, M. J. andvan Oosterom, A. (1987b) Application of the Richardson extrapolation in simulation studies of EEGs.Med. & Biol. Eng. & Comput.,25, 222–226.Google Scholar
  12. Meijs, J. W. H. andPeters, M. J. (1987) The EEG and MEG, using a model of eccentric spheres to describe the head.IEEE Trans.,BME- 34, (12).Google Scholar
  13. Romani, G. L. andLeoni, R. (1984) Localization of cerebral sources by neuromagnetic measurements. InBiomagnetism: applications and theory.Weinberg, H., Stroink, G. andKatila, T. (Eds.), Pergamon Press, Vancouver, 205–220.Google Scholar
  14. Stok, C. J. (1987) EEG/MEG single dipole source estimation.IEEE Trans.,BME-34, 289–296.Google Scholar
  15. Weinberg, H., Brickett, P., Coolsma, F. andBaff, M. (1985) Magnetic localisation of intracranial dipoles: simulations with a physical model.Electroenceph. Clin. Neurophysiol.,64, 159–170.CrossRefGoogle Scholar
  16. Williamson, S. J. andKaufman, L. (1980) Magnetic fields of the cerebral cortex. InBiomagnetism.Erne, S. N., Hahlbohm, H. D. andLuebbig, H. (Eds.), De Gruyter, Berlin, 353–402.Google Scholar

Copyright information

© IFMBE 1988

Authors and Affiliations

  • J. W. H. Meijs
    • 1
  • M. J. Peters
    • 1
  • H. B. K. Boom
    • 1
  • F. H. Lopes da Silva
    • 2
  1. 1.Department of Electrical EngineeringTwente UniversityEnschedeThe Netherlands
  2. 2.Biological CentreUniversity of AmsterdamAmsterdamThe Netherlands

Personalised recommendations