Volume conductor effects on the spatial resolution of magnetic fields and electric potentials from gastrointestinal electrical activity

  • L. A. Bradshaw
  • W. O. Richards
  • J. P. WikswoJr
Article

Abstract

An analysis of the relative capabilities of methods for magnetic and electric detection of gastrointestinal electrical activity is presented. The model employed is the first volume conductor model for magnetic fields from GEA to appear in the literature. A mathematical model is introduced for the electric potential and magnetic field from intestinal electrical activity in terms of the spatial filters that relate the bioelectric sources with the external magnetic fields and potentials. The forward spatial filters are low-pass functions of spatial frequency, so more superficial external fields and potentials contain less spatial information than fields and potentials near the source. Inverse spatial filters, which are reciprocals of the forward filters, are high-pass functions and must be regularised by windowing. Because of the conductivity discontinuities introduced by low-conductivity fat layers in the abdomen, the electric potentials recorded outside these layers required more regularisation than the magnetic fields, and thus, the spatial resolution of the magnetic fields from intestinal electrical activity is higher than the spatial resolution of the external potentials. In this study, two smooth muscle sources separated by 5 cm were adequately resolved magnetically, but not resolved electrically. Thus, sources are more accurately localized and imaged using magnetic measurements than using measurements of electric potential.

Keywords

Magnetogastrogram Electrogastrogram Smooth muscle electrical activity 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Abell, T. L., Camilleri, M., andMalagelada, J.-R. (1985): ‘High prevalence of gastric electrical dysrhythmias in diabetic gastroparesis’,Gastro,88, pp. 1299Google Scholar
  2. Abell, T. L., andMalagelada, J.-R. (1985): ‘Glucagon-evoked gastric dysrhythmias in humans shown by an improved electrogastrographic technique’,Gastro,88, pp. 1932–1940Google Scholar
  3. Bedi, B. S., Kelly, K. A., andHolley, K. E. (1972): ‘Pathways of propagation of the canine gastric pacesetter potential’,Gastro,63, pp. 288–296Google Scholar
  4. Born, M., andWolf, E. (1975): ‘Principles of optics’, Pergamon Press, New YorkGoogle Scholar
  5. Bradshaw, L. A. (1995): ‘Measurement and Modeling of Gastrointestinal Bioelectric and Biomagnetic Fields’. PhD Dissertation, Vanderbilt UniversityGoogle Scholar
  6. Bradshaw, L. A., Allos, S. H., Wikswo, J. P., Jr., andRichards, W. O. (1997): ‘Correlation and comparison of magnetic and electric detection of small intestinal electrical activity’,Am. J. Physiol.,272, (Gastrointest. Liver Physiol. 35), pp. G1159-G1167Google Scholar
  7. Bradshaw, L. A., Ladipo, J. K., Staton, D. J., Wikswo, J. P., Jr., andRichards, W. O. (1999a): ‘The human vector magnetogastrogram and magnetoenterogram’,IEEE Trans. Biomed. Eng.,46, pp. 959–970CrossRefGoogle Scholar
  8. Bradshaw, L. A., Wijesinghe, R. S., andWikswo, J. P., Jr. (1999b): ‘A spatial filter model for analysis of the forward and inverse problems of electroencephalography and magnetoencephalography’,Ann. Biomed. Eng. (in press)Google Scholar
  9. Chen, J. D. Z., andMcCallum, R. W. (1994): ‘Electrogastrographic parameters and their clinical significance’, inChen, J. D. Z., andMcCallum, R. W. (Eds): ‘Electrogastrography: principles and applications’, (Raven Press, New York), pp. 45–73Google Scholar
  10. Chen, J., andMcCallum, R. W. (1992): ‘Gastric slow wave abnormalities in patients with gastroparesis’,Am. J. Gastro.,87, pp. 477–482Google Scholar
  11. Chen, J. D. Z., Schirmer, B. D., andMcCallum, R. W. (1993a): ‘Measurement of electrical activity of the human small intestine using surface electrodes’,IEEE Trans. Biomed. Eng.,40, pp. 598–602Google Scholar
  12. Chen, J. D. Z., Richards, R., andMcCallum, R. (1993b): ‘Frequency components of the electrogastrogram and their correlations with gastrointestinal motility’,Med. Biol. Eng. Comput.,31, pp. 60–67Google Scholar
  13. Daniel, E. E., Carlow, D. R., Wachter, B. T., Sutherland, W. H., andBogoch, A. (1959): ‘Electrical activity of the small intestine’,Gastro,37, pp. 268–281Google Scholar
  14. Daniel, E. E., andSarna, S. (1978): ‘The generation and conduction of activity in smooth muscle’,Ann. Rev. Pharmacol. Toxicol.,18, pp. 145–166Google Scholar
  15. Debinski, H. S., Ahmed, S., Milla, P. J., andKamm, M. A. (1996): ‘Electrogastrography in chronic intestinal pseudoobstruction’,Dig. Dis. Sci.,41(7), pp. 1292–1297CrossRefGoogle Scholar
  16. Devane, S. P., Ravelli, A. M., Bisset, W. M., Smith, V. V., Lake, B. D., andMilla, P. J. (1992): ‘Gastric antral dysrhythmias in children with chronic idiopathic intestinal pseudoobstruction’,Gut,33, pp. 1477–1481Google Scholar
  17. Diamant, N. E., Rose, P. K., andDavison, E. J. (1970): ‘Computer simulation of intestinal slow-wave frequency gradient’,Am. J. Physiol.,291, pp. 1684–1690Google Scholar
  18. Familoni, B. O., Bowes, K. L., Kingma, Y. J., andCote, K. R. (1991): ‘Can transcutaneous recordings detect gastric electrical abnormalities?’,Gut,32, pp. 141–146Google Scholar
  19. Familoni, B. O., Abell, T. L., andBowes, K. L. (1995): ‘A model of gastric electrical activity in health and disease’,IEEE Trans. Biomed. Eng.,42, pp. 647–657CrossRefGoogle Scholar
  20. Fleckenstein, P. (1978): ‘Migrating electrical spike activity in the fasting human small intestine’,Amer. J. Dig. Dis.,23, pp. 769–775Google Scholar
  21. Hamalainen, M. S., andSarvas, J. (1989): ‘Reallistic conductivity geometry model of the human head for interpretation of neuromagnetic fields’,IEEE Trans. Biomed. Eng.,36, pp. 165–171Google Scholar
  22. Hasler, W. L., Kim, M. S., Chey, W. D., Stevenson, V., Stein, B., andOwyang, C. (1995): ‘Central cholinergic and alpha-adrenergic mediation of gastric slow wave dysrhythmias evoked during motion sickness’,Am. J. Physiol.,268, pp. G539-G547Google Scholar
  23. Hongo, M., andOkuno, Y. (1993): ‘Diabetic gastropathy in patients with autonomic neuropathy’,Diab. Med.,10, (Supp. 2), pp. 79S-81SGoogle Scholar
  24. Koch, K. L., Stern, R. M., Stewart, W. R., Vasey, M. W., andSullivan, M. L. (1989): ‘Gastric emptying and gastric myoelectric activity in patients with symptomatic diabetic gastroparesis: Effects of long-term domperidone treatment’,Am. J. Gastroenterol.,84, pp. 1069–1075Google Scholar
  25. Koch, K. L., Stern, R. M., Vasey, M., Botti, J. J., Creasy, G. W., andDwyer, A. (1990): ‘Gastric dysrhythmias and nausea of pregnancy’,Dig. Dis. Sci.,35, pp. 961–968CrossRefGoogle Scholar
  26. Kothapalli, B. (1993): ‘Electrogastrogram simulation using a three-dimensional model’,Med. Biol. Eng. Comput.,31, pp. 482–486Google Scholar
  27. Mintchev, M. P., andBowes, K. L. (1995): ‘Conoidal dipole model of electrical field produced by the human stomach’,Med. Biol. Eng. Comput.,33, pp. 179–184Google Scholar
  28. Mintchev, M. P., andBowes, K. L. (1997): ‘Do increased electrogastrographic frequencies always correspond to internal tachygastria?’,Annals of Biomed. Eng.,25, pp. 1052–1058Google Scholar
  29. Mintchev, M. P., Kingma, Y. J., andBowes, K. L. (1993): ‘Accuracy of cutaneous recordings of gastric electrical activity’,Gastro,104, pp. 1273–1280Google Scholar
  30. Mintchev, M. P., Stickel, A., Otto, S. L., andBowes, K. L. (1997): ‘Reliability of percent distribution of power of the electrogastrogram in recognizing gastric electrical uncoupling?’,IEEE Trans. Biomed. Eng.,44, pp. 1288–1291CrossRefGoogle Scholar
  31. Mirizzi, N., Stella, R., andScafoglieri, U. (1985): ‘A model of extracellular waveshapes of gastric electrical activity’,Med. Biol. Eng. Comput.,23, pp. 33–37Google Scholar
  32. Mirizzi, N., Stella, R., andScafoglieri, U. (1986): ‘Model to simulate the gastric electrical control and response activity on the abdominal wall and on the abdominal surface’,Med. Biol. Eng. Comput.,24, pp. 157–163Google Scholar
  33. Parker, R. L. (1977): ‘Understanding inverse theory’,Ann. Rev. Earth Planet. Sci.,5, pp. 35–64Google Scholar
  34. Pfister, C. J., Hamilton, J. W., Nagel, N., Bass, P., Webster, J. G., andTompkins, W.J. (1988): ‘Use of spectral analysis in the detection of frequency differences in the electrogastrograms of normal and diabetic subjects’,IEEE Trans. Biomed. Eng.,35, pp. 935–941CrossRefGoogle Scholar
  35. Richards, W. O., Garrard, C. L., Allos, S. H., Bradshaw, L. A., Staton, D. J., andWikswo, J. P., Jr. (1995): ‘Nonnvasive diagnosis of mesenteric ischemia using a SQUID magnetometer’,Ann. Surg.,221, pp. 696–705Google Scholar
  36. Richards, W. O., Bradshaw, L. A., Staton, D. J., Garrard, C. L., Liu, F., Buchanan, S., andWikswo, J. P., Jr. (1996): ‘Magnetoenterography (MENG): Noninvasive measurement of bioelectric activity in human small bowel’,Dig. Dis. Sci.,41, pp. 2293–2301CrossRefGoogle Scholar
  37. Rothstein, R. D., Alavi, A., andReynolds, J. C. (1993): ‘Electrogastrography in patients with gastroparesis and effect of long-term cisapride’,Dig. Dis. Sci.,38, pp. 1518–1524Google Scholar
  38. Smout, A. J. P. M., Van Der Schee, E. J., Akkermans, L. M. A., andGrashuis, J. L. (1984): ‘Recording of gastrointestinal electrical activity from surface electrodes’,Scand. J. Gastroenterol., Suppl.96, pp. 11–18Google Scholar
  39. Telander, R. L., Morgan, K. G., Kreulan, D. L., Schmalz, P. F., Kelly, K. A., andSzurszewski, J. H. (1978): ‘Human gastric atony with tachygastria and gastric retention’,Gastro,75, pp. 497–501Google Scholar
  40. Woosley, J. K., Roth, B. J., andWikswo, J. P., Jr. (1985): ‘The magnetic field of a single axon: A volume conductor model’,Math. Biosci.,76, pp. 1–36CrossRefGoogle Scholar
  41. You, C. H., Lee, K. Y., Chey, W. Y., andMenguy, R. (1980): ‘Electrogastrographic study of patients with unexplained nausea, bloating, and vomiting’,Gastro,79, pp. 311–314Google Scholar

Copyright information

© IFMBE 2001

Authors and Affiliations

  • L. A. Bradshaw
    • 1
    • 2
    • 3
  • W. O. Richards
    • 2
    • 4
  • J. P. WikswoJr
    • 1
  1. 1.Living State Physics Group, Department of Physics & AstronomyVanderbilt UniversityNashvilleTennesseeUSA
  2. 2.Department of SurgeryVanderbilt University Medical CenterNashvilleUSA
  3. 3.Lipscomb UniversityNashvilleUSA
  4. 4.Department of SurgeryVeterans' Affairs Medical CenterNashvilleUSA

Personalised recommendations