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Phase‐Modulated binomial RF pulses for fast spectrally‐selective musculoskeletal imaging
Author(s) -
Thomasson David,
Purdy David,
Finn J. Paul
Publication year - 1996
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.1910350416
Subject(s) - pulse (music) , spins , radio frequency , phase (matter)
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.