Abstract
Since the demonstration of blood oxygenation level dependent (BOLD) contrast in magnetic resonance (MR) imaging at 7 and 8.4 T by Ogawa et al. in 1990 [1], the concept of functional magnetic resonance imaging (fMRI) has developed rapidly. Techniques of different complexity have been employed, ranging from conventional gradient echo imaging to advanced echo planar imaging, and a variety of applications have been suggested [2–4]. However, an accurate interpretation of observed BOLD effects in MR images is not always trivial, since the contrast mechanism reflects the combination of several parameters, for example, alterations in blood flow, blood volume, blood oxygenation and oxygen consumption. Furthermore, the possibility to correctly localize an activated region is hampered by the fact that larger vessels or draining veins can generate signal at a distance from the site of true tissue activation, and this large vessel signal contribution is not readily distinguishable from the signal arising from the capillary system within the tissue. In gradient echo imaging, the signal from the capillary system of the activated region is dominated by the T2*-sensitivity, while the signal from large vessels is likely to be a combination of susceptibility effects and inflow effects [3]. Theoretical modelling has suggested that the relative signal enhancement during stimulation (ΔS/S0) is the sum of a contribution from small vessels, showing a quadratic dependence on field strength, and a large vessel component with a linear dependence on field strength [5]. Consequently, experiments at different field strengths could provide further information on the origin of the fMRI contrast in gradient echo imaging. The aim of this study was to experimentally demonstrate activation of human visual and motor cortex at 1.0 T as well as at 1.5 T, and to investigate different aspects of the field strength dependence in fMRI using identical pulse sequences and identical volunteers at both field strengths.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
Preview
Unable to display preview. Download preview PDF.
References
Ogawa S, Lee T-M, Nayak AS, Glynn P (1990) Oxygenation-sensitive contrast in magnetic resonance image of rodent brain at high magnetic fields. Magn Reson Med 10. 14: 68
Frahm J, Merboldt K-D, Hänicke W (1993) Functional MRI of human brain activation at high spatial resolution. Magn 11. Reson Med 29: 139
Kwong KK (1995) Functional magnetic resonance imaging with echo planar imaging. Magn Resonance Q 11: 1
Le Bihan D (ed) (1995) Diffusion and perfusion magnetic resonance imaging. Applications to functional MRI. Raven, 12. New York
Ogawa S, Menon RS, Tank DW, Kim S-G, Merkle H, Eller-mann JM, Ugurbil K (1993) Functional brain mapping by blood oxygenation level-dependent contrast magnetic resonance imaging. Biophys J 64: 803
Henriksen O, Larsson HBW, Ring P, Rostrup E, Stensgaard A, Stubgaard M, Stuhlberg F, SOndergaard L, Thomsen C, Toft P (1993) Functional MR imaging at 1.5 T. Initial results using photic and motoric stimulation. Acta Radiol 34: 101
Turner R, Jezzard P, Wen H, Kwong KK, Le Bihan D, Zeffiro T, Balaban RS (1993) Functional mapping of the human visual cortex at 4 and 1.5 tesla using deoxygenation contrast EPI. Magn Reson Med 29: 277
McKenzie CA, Drost DJ, Carr TJ (1994) The effect of magnetic field strength on signal change AS/S in functional MRI with BOLD contrast. Proc II Soc Magn Reson, p. 433
Bandettini PA, Wong EC, Jesmanowicz A, Prost R, Cox RW, Hinks RS, Hyde JS (1994) MRI of human brain activation at 0.5 T, 1.5 T, and 3.0 T: Comparisons of AR2* and functional contrast to noise ratio. Proc II Soc Magn Reson, p. 434
Gati JS, Menon RS, Ugurbil K, Rutt BK (1995) Experimental determination of the BOLD field dependence in tissue and vessels. Proc III Soc Magn Reson, p. 771
Menon RS, Kim S-G, Hu X, Ogawa S, Ugurbil K (1995) Functional MR imaging using the BOLD approach. Field strength and sequence issues. In: Le Bihan D (ed) Diffusion and perfusion magnetic resonance imaging. Applications to functional MRI. Raven, New York, pp 327–334
Umeda M, Tanaka C, Ebisu T, Fukunaga M, Aoki I, Higuchi T, Naruse S (1995) Comparison of supplementary motor area activation between simple and complex motor task. Proc III Soc Magn Reson, p. 1326
Author information
Authors and Affiliations
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 1996 Springer-Verlag Italia, Milano
About this paper
Cite this paper
Wirestam, R. et al. (1996). Functional Magnetic Resonance Imaging Using Photic and Motor Stimulation: Comparison of Results Obtained at 1.0 T and 1.5 T. In: Pavone, P., Rossi, P. (eds) Functional MRI. Syllabus. Springer, Milano. https://doi.org/10.1007/978-88-470-2194-5_10
Download citation
DOI: https://doi.org/10.1007/978-88-470-2194-5_10
Publisher Name: Springer, Milano
Print ISBN: 978-3-540-75025-3
Online ISBN: 978-88-470-2194-5
eBook Packages: Springer Book Archive