✦ LIBER ✦

Magnetic resonance imaging of blood vessels at high fields: In vivo and in vitro measurements and image simulation

✍ Scribed by Seiji Ogawa; Tso-Ming Lee

Publisher: John Wiley and Sons
Year: 1990
Tongue: English
Weight: 600 KB
Volume: 16
Category: Article
ISSN: 0740-3194
DOI: 10.1002/mrm.1910160103

No coin nor oath required. For personal study only.

✦ Synopsis

Abstract

Unusually high image contrast in vivo magnetic resonance imaging of the brain becomes observable at high magnetic fields when the blood oxygenation level is lowered. The cause of the contrast has been attributed to a magnetic susceptibility effect induced by paramagnetic deoxyhemoglobin in red cells. When the cylinder axis of a blood vessel is not parallel to the main magnetic field, the susceptibility difference produces varying local fields around the blood vessel. In gradient‐echo images, not in spin‐echo images, these local fields cause intravoxel dephasing of the water signal of the surrounding tissue. This description of the contrast enhancement has been confirmed by a series of in vitro blood sample experiments and image simulations. A predicted contrast change has been demonstrated in brain images of a mouse placed at two different orientations in the magnet. From the simulated images, the dependence of the contrast on the field strength has been estimated. © 1990 Academic Press, Inc.

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