3D stack-of-blades gradient echo#

Family:: Gradient echo
Dimensionality:: 3D, slab-selective
Sampling:: PROPELLER in-plane, Cartesian partitions
Readout:: One blade line at one partition per repetition, RF-spoiled

RF-spoiled 3D stack of blades: PROPELLER blades in-plane, Cartesian partitions along z.

Prescription#

pypulseqpp.sequences.gre_stack_of_blades3D_sequence()#

RF-spoiled 3D stack of blades: PROPELLER blades in-plane, Cartesian partitions along z.

A blade is blade_width Cartesian lines centred on k = 0, turned about z by a rotation extension; its partition is an amplitude on the encode pair. The Nyquist set is ceil(pi * n / (2 * blade_width)) blades spread evenly over half a turn; every ry-th of them is played, in order, each line of a blade at every acquired partition before the next line. Acquisitions carry the line as LIN, the blade as SEG and the partition as PAR.

Under partition undersampling the central n_acs_z partitions are acquired in full at every tilt, ahead of the rest, and marked IMA.

Parameters:

plot (bool, default=False) – Draw the finished sequence in SeqEyes.
test_report (bool, default=False) – Print a report on the finished sequence.
write_seq (bool, default=False) – Write the sequence to a .seq file.
seq_filename (str, default=None) – Where to write it; <NAME>.seq when omitted.
system (pypulseqpp.Opts, default=None) – System limits, held under the application’s MAX_GRAD and MAX_SLEW.
fov (float, default=0.22) – Isotropic in-plane field of view (m).
n (int, default=128) – In-plane matrix size.
fov_z (float, default=0.128) – Field of view along the partitions (m). The slab excited is fov_z thick.
n_z (int, default=64) – Number of partitions.
flip_angle_deg (float, default=12.0) – Excitation flip angle (degrees).
te (float | None, default=None) – Echo time (s). None is as short as the readout admits.
tr (float | None, default=None) – Repetition time (s), one per excitation. None is as short as possible.
readout_bandwidth_hz (float, default=250000.0) – Requested receiver bandwidth (Hz).
ry (int, default=1) – Angular undersampling: one blade in every ry of the Nyquist set is played.
rz (int, default=1) – Partition undersampling: one partition in every rz is acquired, the centre one among them.
partial_fourier_z (float, default=1.0) – Fraction of the partition extent acquired, in [0.75, 1].
n_dummy (int, default=32) – Non-acquiring repetitions, at the first blade’s centre line and the centre partition, before the scan.
excitation ({'slab', 'nonselective', 'spsp'}, default='slab') – A slab-selective SLR pulse, a hard pulse, or a slab- and water-selective spectral-spatial pulse.
partition_angle_shift ({'none', 'golden', 'tiny_golden'}, default='none') – How far each partition turns the blades past the previous one, as PARTITION_SHIFTS names the fractions of a half turn.
n_acs_z (int, default=16) – Fully sampled calibration partitions at the centre, acquired at every tilt ahead of the rest when rz > 1.
blade_width (int, default=16) – Phase-encode lines per blade, at most n.

Returns:

The designed sequence.

Return type:

pypulseqpp.Sequence

Raises:

ValueError – If excitation or partition_angle_shift is unknown, an undersampling factor is below one, blade_width is outside [1, n], partial_fourier_z is outside [0.75, 1], or the TE or TR is shorter than the readout takes.

Examples

>>> from pypulseqpp import sequences
>>> seq = sequences.gre_stack_of_blades3D_sequence(n=32, n_z=4, blade_width=8)
>>> seq.check_timing()[0]
True

Designed and drawn#

3D stack-of-blades gradient echo

3D stack-of-blades gradient echo

Contents

3D stack-of-blades gradient echo#

Prescription#

Designed and drawn#

See also#