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Oxygen‐sensitive contrast in blood for steady‐state free precession imaging
Author(s) -
Dharmakumar Rohan,
Hong Juimiin,
Brittain Jean H.,
Plewes Donald B.,
Wright Graham A.
Publication year - 2005
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.20393
Subject(s) - steady state free precession imaging , contrast (vision) , oxygen , nuclear magnetic resonance , blood oxygen level dependent , precession , steady state (chemistry) , chemistry , magnetic resonance imaging , physics , optics , medicine , radiology , astronomy , organic chemistry
Steady‐state free precession (SSFP) methods have gained widespread recognition for their ability to provide fast scans at high signal‐to‐noise ratio. This paper demonstrates that such methods are also capable of reflecting functional information, particularly blood oxygenation state. It is well known that SSFP signals show substantial sensitivity to small off‐resonance frequency variations. However, that mechanism cannot explain the oxygen‐sensitive contrast in blood that was observed with steady‐state methods using phase‐cycled radiofrequency pulses. From theoretical and experimental models it is demonstrated that the mechanism responsible for such contrast originates from the motion of spins through local field inhomogeneities in and around deoxygenated red blood cells. In addition, this work shows that it is critical to choose the scan parameters carefully for robust oxygen‐sensitive contrast. Finally, it is demonstrated that it is possible to build a quantitative model that incorporates the Luz–Meiboom model, which had been used in the past to estimate quantitative measures of vascular blood oxygen levels. It is envisioned that this method could be instrumental in real‐time imaging focused on detecting diseases where the oxygen state of blood is impaired. Magn Reson Med 53:574–583, 2005. © 2005 Wiley‐Liss, Inc.