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Proceedings Paper

Macroscopic static field inhomogeneity in the human brain during MRI examination
Author(s): Haiying Liu; Edward Michel; Sean O. Casey; Walter A. Hall; Charles L. Truwit
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Paper Abstract

The macroscopic static field inhomogeneity is not only the source of MR signal loss in gradient echo based imaging techniques, but also the source of geometrical image distortion as well as a limitation of spectral resolution. This piece of information is useful for both active shimming coil design and clinical imaging application. In order to further understand the spatial variation of the macroscopic background static field in human brain during MRI examination, this static field inhomogeneity was measured from the adult human volunteers with a volumetric imaging scheme, which was based on a 3D gradient echo technique with two consecutive gradient echoes. All the human volunteers were scanned in supine position using a birdcage headcoil on a 1.5 T clinical whole body scanner. We have constructed a high resolution 3D static field map over the brain volume. All experimental results have shown consistently that there are mainly two spots in the brain tissue volume exhibiting relatively severe static magnetic field inhomogeneity . They are normally located in the brain areas in the inferior frontal lobe immediately anterior to the nasal cavity and in the inferior temporal lobe above the ear canals, where air spaces exist in the vicinity. At those locations, the observed offset frequency in the proton resonance reached about 50 Hz over 5 mm distance along the z direction at 1.5 Tesla, corresponding to 1.5 ppm/cm locally.

Paper Details

Date Published: 3 May 2002
PDF: 4 pages
Proc. SPIE 4682, Medical Imaging 2002: Physics of Medical Imaging, (3 May 2002); doi: 10.1117/12.465582
Show Author Affiliations
Haiying Liu, Univ. of Minnesota (United States)
Edward Michel, Univ. of Minnesota (United States)
Sean O. Casey, Univ. of Minnesota (United States)
Walter A. Hall, Univ. of Minnesota (United States)
Charles L. Truwit, Univ. of Minnesota (United States)


Published in SPIE Proceedings Vol. 4682:
Medical Imaging 2002: Physics of Medical Imaging
Larry E. Antonuk; Martin Joel Yaffe, Editor(s)

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