## Abstract Chemical shift‐based multipoint water‐fat separation methods have been applied in balanced steady‐state free precession (bSSFP) sequences because of the high signal‐to‐noise‐ratio (SNR) attainable. In this approach the echo formation is approximated to occur concurrently for both water
On the origin of apparent low tissue signals in balanced SSFP
✍ Scribed by O. Bieri; K. Scheffler
- Publisher
- John Wiley and Sons
- Year
- 2006
- Tongue
- English
- Weight
- 687 KB
- Volume
- 56
- Category
- Article
- ISSN
- 0740-3194
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✦ Synopsis
Abstract
Balanced steady‐state free precession (bSSFP) has become increasingly important in clinical applications. Its signal properties have been investigated over several years by many groups, and various critical factors for bSSFP signal intensity and stability, such as off‐resonances, flow, and eddy currents, have been identified. It is generally accepted that bSSFP signal intensity is a function of relaxation times, excitation angles, and spin densities only. While this is true for simple phantoms, it appears that signals from tissues are significantly less intense than predicted by theory. This work demonstrates that the molecular origin of this apparent signal reduction is due to on‐resonance magnetization transfer (MT). High flip angles in combination with very short repetition times (TRs), as commonly used for bSSFP, lead to a considerable saturation in the fraction of macromolecular (MM) pool protons. As a result, bSSFP signal is strongly attenuated by up to a factor of 2 in the human brain compared to the signal expected from theory. Magn Reson Med, 2006. © 2006 Wiley‐Liss, Inc.
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