Phase-Modulated binomial RF pulses for fast spectrally-selective musculoskeletal imaging
✍ Scribed by David Thomasson; David Purdy; J. Paul Finn
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 667 KB
- Volume
- 35
- Category
- Article
- ISSN
- 0740-3194
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✦ Synopsis
Abstract
Two fat‐suppressed three‐dimensional gradient echo pulse sequences, FLASH and DESS (__D__ouble __E__cho in Steady‐State), that have significantly reduced scan time compared with conventional chemical shift fat‐suppression sequences are presented. This fat‐suppression technique is based on selectively exciting water spins using a time‐optimized binomial RF pulse pair at the water resonance frequency with a null in the excitation profile at the fat frequency. To minimize the total pulse length, the delay between the binomial components of the RF pulse is decreased from a standard jump‐return implementation. To maintain the proper null frequency, the phase of the second RF pulse is shifted such that it returns the fat resonance back to its initial z position while further tipping the water spins. Nonselective phase‐modulated RF pulse pairs can be implemented in 1.20 ms at 1.0 T, significantly reducing the minimum TR.