OffResonanceSaturation

class pypulseqpp.sequences.OffResonanceSaturation

Bases: RfModule

Repeat one off-resonance pulse, followed by an optional three-axis spoiler.

Parameters:

• system (Opts) – System limits.

• rf_prep (RfEvent) – The pulse to play.

• n_pulses (int, default=1) – Pulses in the train.

• spoiling_cycles (float, default=4.0) – Dephasing of the final spoiler, in cycles across voxel_size_m. Zero omits the spoiler, as required for a pulse used for its phase effect rather than for saturation.

• voxel_size_m (float, default=0.001) – Length the dephasing is counted over (m).

• labels (Sequence[str], default=None) – Counters emitted on the first pulse’s block.

Attributes:

• rf_prep (RfEvent) – The pulse, published once however many times it is played.

• gx_spoil, gy_spoil, gz_spoil (GradEvent) – The closing spoiler, when there is one.

• prep_labels (LabelEvent | list[LabelEvent]) – One per name in labels.

Raises:

ValueError – If n_pulses is below one, or a spoiling argument is out of range.

Examples

>>> import numpy as np
>>> import pypulseqpp.sequences as design
>>> import pypulseqpp as pp
>>> system = pp.Opts()
>>> pulse = pp.make_gauss_pulse(
...     flip_angle=np.deg2rad(500), duration=8e-3, freq_offset=-1500.0,
...     use="saturation", system=system,
... )
>>> prep = design.OffResonanceSaturation(system, pulse, n_pulses=3)
>>> len(prep.blocks)
4

>>> prep.blocks[0] == prep.blocks[1] == prep.blocks[2]
True

Three pulses back to back, and the longitudinal magnetization they leave across the spectrum:

(svg)

(svg)

Methods

init_module	Build the module's block layout; implemented by the subclass.
publish	Publish events from the caller's locals and register keyword aliases.
register	Publish named events without requiring prior block registration.
sim_rf	Simulate this module's pulse across off-resonance.

Attributes

blocks	Return block tuples in play order, retaining the original event objects.
duration	Duration of the module in seconds.
seq	Sequence holding the module's construction-time block layout.