Signal Sources in Bold Contrast FMRI

  • Robert Turner
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 413)


When a non-diffusible paramagnetic contrast agent is present in the blood, the mechanism of MRI signal loss is as follows. The contrast agent has a magnetic susceptibility higher than that of blood or brain tissue, and thus creates magnetic field inhomogeneities within and surrounding the vessels in which it passes. Gradient-echo imaging is highly sensitive to such quasi-random non-uniformities of the magnetic field, by allowing the dephasing effect of the magnetic field inhomogeneity to accumulate over a period of 40–80 ms before data acquisition. Within a voxel containing blood vessels the nuclear spins experience spatially varying magnetic fields, and consequently precess at different rates depending on position. The result is a loss of phase coherence within the voxel, and thus a decrease in signal relative to when the contrast agent is absent.


Magnetic Field Inhomogeneity Oxygenation Change Human Visual Cortex Cranial Window Ocular Dominance Column 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Stehling M.K., Turner R., Mansfield P., 1991, Echo-planar imaging: magnetic resonance imaging in a fraction of a second. Science 254:43–50.ADSCrossRefGoogle Scholar
  2. 2.
    Pauling, L. and Coryell, CD., 1936, The magnetic properties and structure of hemoglobin, oxyhemoglobin and carbonmonoxyhemoglobin. Proc Natl Acad Sci USA 22:210–216.Google Scholar
  3. 3.
    Brindle, K.M., Brown, F.F., Campbell, I.D., Grathwohl, C, Kuchel, P.W., 1979, Application of spin-echo nuclear magnetic resonance to whole-cell systems. Biochem J, 180:37–44.Google Scholar
  4. 4.
    Thulborn, K.R., Waterton, J.C., Matthews, P.M., Radda, G.K., 1982, Oxygenation dependence of the transverse relaxation time of water protons in whole blood at high field. Biochim. Biophys. Acta. 714:265–270.CrossRefGoogle Scholar
  5. 5.
    Brooks, R.A., Di Chiro, G., 1987, Magnetic resonance imaging of stationary blood: a review. Med. Phys. 14:903–913.CrossRefGoogle Scholar
  6. 6.
    Ogawa, S., Lee, T-M., Nayak, A.S., Glynn, P., 1990, Oxygenation-sensitive contrast in magnetic resonance image of rodent brain at high magnetic fields. Magn. Reson. Med. 14:68–78.CrossRefGoogle Scholar
  7. 7.
    Turner, R., LeBihan, D., Moonen, C.T.W., DesPres, D. and Frank, J., 1991, Echo-planar time course MRI of cat brain oxygenation changes, Magn. Reson. Med., 22:159–166.Google Scholar
  8. 8.
    Turner, R., Le Bihan, D., Maier, J., Vavrek, R., Hedges, L.K., Pekar, J., 1990, Echo-planar imaging of intravoxel incoherent motion. Radiology 177:407–414.Google Scholar
  9. 9.
    Doyle, M., Turner, R., Cawley, M., Glover, P., Morris, G.K., Chapman, B., Ordidge, R.J., Coxon, R., Coupland, R.E., Worthington, B.S., Mansfield, P., 1986, Real-time cardiac imaging of adults at video frame rates by magnetic resonance imaging. Lancet ii:682.CrossRefGoogle Scholar
  10. 10.
    Jezzard, P., Heineman, F., Taylor, J., Despres, D., Wen, H., Balaban, R.S. and Turner, R., 1994, Comparison of EPI gradient-echo contrast changes in cat brain caused by respiratory challenges with direct simultaneous spectrophotometric evaluation of cerebral oxygenation via a cranial window, NMR in Biomedicine, 7:35–44.CrossRefGoogle Scholar
  11. 11.
    Ogawa, S, Tank, D.W., Menon, R., Ellerman, J.M., Kim, S-G., Merkle, H. and Ugurbil, K., 1992, Intrinsic signal changes accompanying sensory stimulation: functional brain mapping with magnetic resonance imaging, Proc. Natl. Acad. Sci. USA, 89:5951–5955.ADSCrossRefGoogle Scholar
  12. 12.
    Kwong, K.K., Belliveau, J.W., Chesler, D.A., Goldberg, I.E., Weisskoff, R.M., Poncelet, B.P., Kennedy, D.N., Hoppel, B.E., Cohen, M.S., Turner, R., Cheng, H-M., Brady, T.J., Rosen, B.R., 1992, Dynamic magnetic resonance imaging of human brain activity during primary sensory stimulation. Proc Natl Acad Sci USA 89:5675–5679.ADSCrossRefGoogle Scholar
  13. 13.
    Fox, P.T. and Raichle, M.E., 1986, Focal physiological uncoupling of cerebral blood flow and oxidative metabolism during somatosensory stimulation in human subjects. Proc. Natl. Acad. Sci. USA 83:1140–4.ADSCrossRefGoogle Scholar
  14. 14.
    Penfield, W., 1933, The evidence for a cerebral vascular mechanism in epilepsy. Ann Intern Med 7:303–310.CrossRefGoogle Scholar
  15. 15.
    Turner, R., Jezzard, P., Wen, H., Kwong, K.K., Le Bihan, D., Zeffiro, T., Balaban, R.S., 1993, Functional mapping of the human visual cortex at 4 tesla and 1.5 tesla using deoxygenation contrast EPI. Magn. Reson. Med. 29:277–281.CrossRefGoogle Scholar
  16. 16.
    Fisel, C.R., Ackerman, J.L., Buxton, R.B., Garrido, L., Belliveau, J.W., Rosen, B.R., Brady, T.J., 1991, MR contrast due to microscopically heterogenous magnetic susceptibility: numerical simulations and applications to cerebral physiology. Magn. Reson. Med. 17:336–347.CrossRefGoogle Scholar
  17. 17.
    Ogawa, S., Menon, R.S., Tank, D.W., Kim, S-G., Merkle, H., Ellerman, J.M. and Ugurbil, K., 1993, Functional brain mapping by blood oxygenation level-dependent contrast magnetic resonance imaging. Biophys. J. 64:803–812.CrossRefGoogle Scholar
  18. 18.
    Weisskoff, R.M., Zuo, C.S., Boxerman, J.L. and Rosen, B.R., 1994, Microscopic susceptibility variation and transverse relaxation: theory and experiment. Magn. Reson. Med., 31:601–610.CrossRefGoogle Scholar
  19. 19.
    Kennan, R.P., Zhong, J. and Gore, J.C., 1994, Intravascular susceptibility contrast mechanisms in tissues. Magn. Reson. Med., 31:9–21.CrossRefGoogle Scholar
  20. 20.
    Boxerman, J.L., Weisskoff, R.M., Kwong, K.K., Davis, T.L., Rosen, B.R., 1994, The intravascular contribution to fMRI signal change: modelling and diffusion-weighted in vivo studies. Proc. Soc. Magn. Reson. (1994)2:619.Google Scholar
  21. 21.
    Menon, R.S., Hu, X., Adriany, G., Andersen, P., Ogawa, S. and Ugurbil, K., 1994, Comparison of spinecho EPI, asymmetric spin-echo EPI and conventional EPI applied to functional neuroimaging: the effect of flow crushing gradients on the BOLD signal. Proc. Soc. Magn. Reson. (1994) 2:622.Google Scholar
  22. 22.
    Hossmann, K-A., Ueki, M., Kocher, M. and Linn, F., 1991, Multiparametric imaging of coupling between functional activity, blood flow and metabolism uder physiological and pathophysiologic conditions, in Brain Work and Mental Activation, Alfred Benzon Symposium 31, (Lassen NA, Ingvar DH, Raichle ME and Friberg L, eds) pp 158–173. Copenhagen: Munksgaard.Google Scholar
  23. 23.
    Duling, B., Matsuki, T., Segal, S., Conduction in the resistance-vessel wall: contributions to vasomotor tone and vascular communication. In: Bevan, J.A. ed. The Resistance Vasculature. Totowa, NJ: Humana Press, 1991:193-215.Google Scholar
  24. 24.
    Frostig, R.D., Lieke, E.E., Ts’o, D.Y., Grinvald, A., 1990, Cortical functional architecture and local coupling between neuronal activity and the microcirculation revealed by in-vivo high-resolution optical imaging of intrinsic signals. Proc Natl Acad. Sci USA 87:6082–6086.ADSCrossRefGoogle Scholar
  25. 25.
    Turner, R. and Grinvald, A., 1994, Direct visualization of patterns of deoxygenation and reoxygenation in monkey cortical vasculature during functional brain activation. Proc. Soc. Magn. Reson. (1994) 1:430.Google Scholar
  26. 26.
    Lai, S., Hopkins, A.L., Haacke, E.M., Li, D., Wasserman, B.A., Buckley, P., Friedman, L., Meltzer, H., Hedera, P., Friedland, R., 1993, Identification of vascular structures as a major source of signal contrast in high resolution 2D and 3D functional activation imaging of the motor cortex at 1.5 T: preliminary results. Magn. Reson. Med. 30:387–392.CrossRefGoogle Scholar
  27. 27.
    Segebarth, C, Belle, V., Delon, C, Massarelli, R., Decety, J., Le Bas, J.F., Decorps, M., Benabid, A.L., 1994, Functional MRI of the human brain. Predominance of signals from extracerebral veins. NeuroReport 5, 813–816.CrossRefGoogle Scholar
  28. 28.
    Henkelman, R.M., Neil, J.J., Xiang, Q-S., 1994, A quantitative interpretation of IVIM measurements of vascular perfusion in the rat brain. Magn. Reson. Med. 32:464–469.CrossRefGoogle Scholar
  29. 29.
    Wiederman, M.P., 1963, Dimensions of blood vessels from distributing artery to collecting vein. Circ. Res. 12:375.CrossRefGoogle Scholar
  30. 30.
    Frahm, J., Merboldt, K-D., Hänicke, W., Kleinschmidt, A., Boecker, H., 1994, Brain or vein-oxygenation or flow? On signal physiology in functional MRI of human brain activation. NMR in Biomedicine 7:45–53.CrossRefGoogle Scholar
  31. 31.
    Baker, J.R., Hoppel, B.E., Stern, C.E., Kwong, K.K., Weisskoff, R.M., Rosen, B.R., 1993, Dynamic functional imaging of the complete human cortex using gradient echo and asymmetric spin-echo echo-planar magnetic resonance imaging. Proc. Soc. Magn. Reson. Med. (1993) 3:1400.Google Scholar

Copyright information

© Springer Science+Business Media New York 1997

Authors and Affiliations

  • Robert Turner
    • 1
  1. 1.Wellcome Department of Cognitive NeurologyInstitute of NeurologyLondonUK

Personalised recommendations