make_spiral_readout

pulserver.blocks.make_spiral_readout(system, fov, npix, narms=1, fs_npix=None, trans_dur=0.5, spiral_type='outward', has_adc=True)

Prepare spiral readout.

Parameters:

• system (pypulseq.Opts) – System limits.

• fov (float) – Field of View in [mm].

• npix (int) – Matrix size.

• narms (int, optional) – Number of interleaves. The default is 1.

• fs_npix (int, optional) – Matrix size for fully-sampled region. The default is None (constant density spiral).

• trans_dur (float, optional) –

  Fractional duration of transition region for dual-density spiral, referred to the duration of fully sampled region, i.e.:

  • npts_transition = trans_dur * npts_fully_sampled

  It must be >= 0.5. The default is 0.5.

• spiral_type (str, optional) –

  Spiral variant. Can be:

  • "outward": center-to-periphery.

  • inward: periphery-to-center.

  • in-out: inward followed by outward spiral.

  The default is outward.

• has_adc (bool, optional) – If True, read_block contains and ADC event. Otherwise, it does not (e.g., dummy shots for steady-state preparation). The default is True.

Returns:

• read_block (dict) – Readout block dictionary with the following keys:

  • gxSimpleNamespace

    X-component of readout gradient event.

  • gySimpleNamespace

    Y-component of readout gradient event.

  • adcSimpleNamespace

    ADC event (only if has_adc is True).

• hdr (SimpleNamespace) – Spiral header containing

  • trajnp.ndarray

    K-space trajectory of shape (2, len(arm)).

  • idxtuple

    Indexes for ADC start (idx[0]) and stop (idx[1]).

Return type:

tuple[dict, SimpleNamespace]