Sequence.calculate_kspace

Sequence.calculate_kspace()

Integrate the gradients with excitation resets and refocusing.

Each block’s rotation is applied. K-space coordinates are in 1/m.

Parameters:

• trajectory_delay (float | ArrayLike, default=0.0) – Per-axis timing correction (s); positive values advance the gradient.

• gradient_offset (float | ArrayLike, default=0.0) – A background gradient per axis, in Hz/m.

• block_range (Sequence[int], default=None) – Two 1-based block indices; only those blocks are followed.

Returns:

• k_traj_adc (NDArray[np.float64]) – (3, n): the k-space location of each ADC sample, in 1/m.

• k_traj (NDArray[np.float64]) – Full trajectory in 1/m, sampled through ramps and at event times.

• t_excitation (NDArray[np.float64]) – Centre of each excitation pulse, in seconds from the start of the selected range.

• t_refocusing (NDArray[np.float64]) – Centre of each refocusing pulse, in seconds from the same origin.

• t_adc (NDArray[np.float64]) – Time of each ADC sample, in seconds from the same origin.

Examples

>>> import numpy as np
>>> import pypulseqpp as pp
>>> seq = pp.Sequence(pp.Opts())
>>> seq.add_block(pp.make_block_pulse(np.pi / 2, duration=1e-3))
1
>>> seq.add_block(pp.make_adc(num_samples=64, duration=3.2e-3))
2
>>> k_traj_adc, k_traj, t_excitation, t_refocusing, t_adc = seq.calculate_kspace()
>>> k_traj_adc.shape, t_excitation
((3, 64), array([0.0005]))