2D PROPELLER gradient echo

2D PROPELLER gradient echo#

Family:

Gradient echo

Dimensionality:

2D, multi-slice

Sampling:

PROPELLER blades

Readout:

One line of one blade per repetition, RF-spoiled

RF-spoiled, multi-slice 2D PROPELLER gradient echo: one blade line per repetition.

Prescription#

pypulseqpp.sequences.gre_propeller2D_sequence()#

RF-spoiled, multi-slice 2D PROPELLER gradient echo: one blade line per repetition.

A blade is blade_width Cartesian lines centred on k = 0, and every blade is the same lines turned by a rotation extension. 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 by line. Slices are dealt into packets, and ordered within one, as gre2D_sequence deals them. Every acquisition carries its line as LIN, its blade as SEG and its slice as SLC.

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.

  • n_slices (int, default=1) – Number of slices.

  • slice_thickness (float, default=0.005) – Slice thickness (m).

  • slice_spacing (float, default=0.0) – Gap between adjacent slices (m); zero is contiguous.

  • flip_angle_deg (float, default=12.0) – Excitation flip angle (degrees).

  • te (float | None, default=0.008) – Echo time (s). None is as short as the readout admits.

  • tr (float | None, default=0.25) – Repetition time between successive excitations of one slice (s). None is as short as possible, and puts every slice in one packet.

  • 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.

  • n_dummy (int, default=16) – Non-acquiring repetitions, at the first blade’s angle, before each packet.

  • blade_width (int, default=16) – Phase-encode lines per blade, at most n.

Returns:

The designed sequence.

Return type:

pypulseqpp.Sequence

Raises:

ValueError – If ry is below one, blade_width is outside [1, n], or the TR cannot hold one slice.

Examples

>>> from pypulseqpp import sequences
>>> seq = sequences.gre_propeller2D_sequence(n=32, blade_width=8, tr=None)
>>> seq.check_timing()[0]
True

Designed and drawn#

2D PROPELLER gradient echo

2D PROPELLER gradient echo

See also#

Other gradient echo sequences: gre2D_sequence, gre3D_sequence, gre_multiecho2D_sequence, gre_multiecho3D_sequence, gre_radial2D_sequence, gre_stack_of_stars3D_sequence, gre_spiral2D_sequence, gre_stack_of_spirals3D_sequence, gre_stack_of_blades3D_sequence.

The same sampling in another family: se_propeller2D_sequence.

Every shipped sequence is listed in the catalogue.