RF pulse design

RF events, from the basic factories to designed pulses, and their analysis. Flip angles are in rad, RF amplitudes and frequency offsets in Hz, phase offsets in rad and durations in s. With return_gz, a slice-selective design also returns its slice-selection and rephasing gradients; Events and blocks describes the RF event.

Pulse factories

Object	Input	Returns	Purpose
make_adiabatic_pulse	Sweep type, adiabaticity, bandwidth, duration	RF event; optional slice-select and rephasing gradients	Adiabatic (B1-insensitive) frequency sweep.
make_arbitrary_rf	Complex waveform, flip angle	RF event; optional slice-select gradient	RF event from a given waveform.
make_block_pulse	Flip angle, duration or bandwidth	RF event	Hard (rectangular) pulse.
make_gauss_pulse	Flip angle, duration, time-bandwidth product	RF event; optional slice-select and rephasing gradients	Gaussian pulse.
make_half_passages	Duration, adiabaticity, sweep type	Two RF events, down and up	Adiabatic half-passage pair.
make_sinc_pulse	Flip angle, duration, time-bandwidth product	RF event; optional slice-select and rephasing gradients	Sinc pulse.

SLR and multidimensional design

Object	Input	Returns	Purpose
make_slr_pulse	Flip angle, duration, time-bandwidth product, pulse and filter type	RF event; optional slice-select and rephasing gradients	Shinnar-Le Roux design.
make_recursive_slr_pulses	Number of segments, time-bandwidth product, T1, segment TR	One RF event per segment; optional refocusing pulse	Equal transverse magnetisation per segment.
make_sms_pulse	RF event, number of bands, band spacing (Hz)	Modulated RF event; band offsets (Hz); complex weights	Simultaneous multi-slice modulation.
make_spsp_pulse	Flip angle, slice thickness, spectral bandwidth	RF event; alternating gradient; optional rephaser	Spectral-spatial pulse.
make_2d_selective_pulse	Flip angle, FOV, matrix, target or size	RF event; per-axis gradients; rephasers	Small-tip 2D-selective pulse on a spiral.

Slice encoding

Object	Input	Returns	Purpose
make_gslider_pulse	Flip angle, sub-slice count, sub-slice index, phase (rad)	RF event; optional slice-select and rephasing gradients	gSlider slab encoding.
make_hadamard_pulse	Flip angle, Hadamard order, row	RF event; optional slice-select and rephasing gradients	Hadamard slab encoding.
make_pins_pulse	Flip angle, slice thickness, slice separation (m)	RF event; blip gradient; rephaser	PINS multiband excitation.

B1 selection

B1 amplitudes of these designs are inputs in T; the returned RF events are in Hz.

Object	Input	Returns	Purpose
make_b1_selective_pulse	Flip angle, amplitude (T), relative B1 passband	RF event	B1-selective excitation.
make_b1_gslider_pulse	Flip angle, amplitude (T), sub-band count and index	RF event	B1-selective gSlider encoding.
make_b1_hadamard_pulse	Flip angle, amplitude (T), Hadamard order, row	RF event	B1-selective Hadamard encoding.
make_bloch_siegert_pulse	Amplitude (T), duration, sweep shape, side of resonance	RF event	Adiabatic Bloch-Siegert B1 encoding.

Parallel transmit

A dynamic pTx pulse is one RF event holding each transmit channel’s waveform in turn over a shared time base.

Object	Input	Returns	Purpose
make_ptx_pulse	Complex waveforms (channels, samples) (Hz)	pTx RF event	Dynamic pTx pulse.
split_ptx_pulse	pTx RF event	Complex waveforms (channels, samples) (Hz)	Per-channel waveforms of a pTx pulse.
calc_rf_shim	Complex B1+ maps per channel, mask, target	Complex weights (channels,)	Magnitude least-squares RF shim.
make_spokes_pulse	Flip angle, B1+ maps, FOV, slice thickness	pTx RF event; gradients; rephasers	Spokes pTx excitation.

Analysis and simulation

Object	Input	Returns	Purpose
calc_rf_bandwidth	RF event, cutoff	Bandwidth (Hz); optional spectrum and frequency axis	Bandwidth from the envelope spectrum.
calc_rf_center	RF event	Centre time (s); sample index	RF pulse centre.
calc_rf_power	RF event, time step	Energy (Hz² s), peak power (Hz²), RMS amplitude (Hz)	RF power, as MATLAB Pulseq calcRfPower.
sim_bloch	Complex B1 (Hz), Bz (Hz), time step	Final magnetisation (P, 3)	Hard-pulse Bloch simulation, no relaxation.
sim_rf	RF event, rephase factor	Mz and Mxy profiles, frequency axis (Hz), refocusing efficiency	Off-resonance profile, no relaxation.