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Abstract #2399

B1+-Selective RF Pulses and Their Design Using a Rotated Shinnar-Le Roux Algorithm

William A. Grissom1, Mark D. Does1

1Biomedical Engineering, Vanderbilt University, Nashville, TN, United States

A new class of B1+-selective RF pulses is presented that produce excitation only over a prescribed |B1+|, and are designed using the Shinnar-Le Roux algorithm. The pulses' amplitude waveforms resemble refocused gradient trapezoids, while their frequency waveforms resemble sine-modulated slice-selective pulses. Simulated and experimental validation results are presented, including a simulated comparison to an adiabatic (BIR-4) pulse. The pulses could be used for reduced-FOV imaging based on B1+, or in place of non-selective adiabatic pulses, where they would have the advantage of providing a uniform excitation over only a prescribed B1+ range, with a minimum pulse duration.

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Keywords

adapted adiabatic alternative alto amplifier amplitude anywhere application approaches assumed audience axes axial axis balanced band bandwidth biomedical birdcage bottom bright central class close coil compelling components constant coordinate corners describe design designed designing desired deviation droop dual duration engineering engineers equivalent excitation excitations excite excited excites experimental field fields flat frequency function generate gradient highest implemented independent like likely lowest magnetization mark measured modulated modulation nominal normalized note outside pass peak phantom plots powers predicted prescribed produce profile profiles pulse pulses purely real reduced resembles ripples rotated rotating rotations scientists selective selectively simulated simulation simulations sine slice solution specify spectrometer spin system target terms theory transition transverse trapezoid uniform unmoved useful vial waveform waveforms width zero