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Obtaining blood oxygenation levels from MR signal behavior in the presence of single venous vessels
Author(s) -
Sedlacik Jan,
Rauscher Alexander,
Reichenbach Jürgen R.
Publication year - 2007
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.21283
Subject(s) - imaging phantom , oxygenation , signal (programming language) , blood oxygenation , nuclear magnetic resonance , spin echo , cylinder , dephasing , venous blood , magnetic resonance imaging , blood volume , biomedical engineering , in vivo , physics , materials science , chemistry , mathematics , optics , medicine , radiology , computer science , geometry , functional magnetic resonance imaging , condensed matter physics , microbiology and biotechnology , anesthesia , biology , cardiology , programming language
Abstract The MR signal decay in gradient echo sequences includes signal loss due to spin dephasing caused by static magnetic field inhomogeneities. This decay can be calculated for different geometries of the susceptibility distribution, such as spheres, cylinders, or cylinder networks. In particular, the model of an infinitely long cylinder is a good approximation for single straight blood vessels. Blood oxygenation and blood volume fraction are important parameters, which influence the signal in a characteristic way. In this work the signal decays for a single cylindrical vessel were investigated and evaluated in simulations, phantom measurements as well as in vivo measurements of small single veins in the human brain by using a 3D multiecho gradient echo sequence. Good agreement between simulations and phantom experiments was obtained for different experimental settings. Based on the simulations, physiologically consistent values of venous blood oxygenation level, Y , were extracted from the in vivo measurements of different veins and volunteers ( Y = 0.55 ± 0.02). The methods ability to measure changes in venous blood oxygenation induced by carbogen breathing was demonstrated in one volunteer, where an increase from Y ≈ 0.5 to Y ≈ 0.7 was observed. Magn Reson Med 58:1035–1044, 2007. © 2007 Wiley‐Liss, Inc.