SpatialSelectiveExcitation#

class pypulseqpp.sequences.SpatialSelectiveExcitation[source]#

Bases: RfModule

SLR excitation with a selection gradient and optional rephasing.

A slice publishes separate gz and gz_reph events in two blocks. With is_slab=True, rephasing is merged into gz in one block. Set rephase=False to omit it; a readout may instead include the rephaser’s moment.

Parameters:

system (pypulseqpp.Opts) – System limits.
flip_angle_deg (float) – Nominal flip angle (degrees).
thickness_m (float) – Slice or slab thickness (m).
duration_s (float, default=0.003) – Pulse duration (s).
is_slab (bool, default=False) – Merge the rephaser into the selection gradient, as above.
rephase (bool, default=True) – Include a slice rephaser.
time_bw_product (float, default=4.0) – Time-bandwidth product. Higher is a squarer profile and a longer pulse at the same bandwidth.
axis ({'z', 'x', 'y'}, default='z') – Selection axis.
pulse_type ({'st', 'ex', 'se', 'inv', 'sat'}, default='st') – SLR design family. "ex" for a large-tip excitation, "se" for a refocusing pulse.
use (str, default='excitation') – Pulseq RF-use tag, used by trajectory integration.
passband_ripple (float, default=0.01) – Ripple allowed in each band of the slice profile.
stopband_ripple (float, default=0.01) – Ripple allowed in each band of the slice profile.

Attributes:

rf (RfEvent) – The pulse. Its delay already places it on the gradient’s flat top.
gz (TrapEvent or GradEvent) – The selection gradient; under is_slab the rephaser is part of it.
gz_reph (TrapEvent) – The rephaser. Only when not is_slab and rephase.
selection_amplitude (float) – Plateau amplitude of the selection lobe (Hz/m), which a slice offset is converted against: freq_offset = selection_amplitude * position.

Raises:

ValueError – If thickness_m or duration_s is not positive, or axis is not a gradient channel.

Examples

>>> import pypulseqpp.sequences as design
>>> import pypulseqpp as pp
>>> slice_ = design.SpatialSelectiveExcitation(pp.Opts(), 15.0, 5e-3)
>>> len(slice_.blocks), slice_.gz_reph.channel
(2, 'z')

>>> slab = design.SpatialSelectiveExcitation(pp.Opts(), 8.0, 0.12, is_slab=True)
>>> len(slab.blocks), slab.gz.type
(1, 'grad')

The module diagram and simulated slice profile are generated from the same RF event and selection gradient:

../_images/pypulseqpp-sequences-SpatialSelectiveExcitation-1_00.svg — (`svg`)#

../_images/pypulseqpp-sequences-SpatialSelectiveExcitation-1_01.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.