mprage_sim

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mprage_sim#

torchsim.mprage_sim(TI, flip, TRspgr, nshots, T1, diff=None, inv_efficiency=1.0, M0=1.0, chunk_size=None, device=None)[source]#

MPRAGE simulator wrapper.

Parameters:

  • TI (float | npt.ArrayLike, optional) – Inversion time (s) in milliseconds.

  • flip (float | npt.ArrayLike) – Flip angle train in degrees of shape (2,). If scalar, assume same angle for both blocks.

  • TRspgr (float) – Repetition time in milliseconds for each SPGR readout.

  • nshots (int | npt.ArrayLike) – Number of SPGR readout within the inversion block of shape (npre, npost) If scalar, assume npre == npost == 0.5 * nshots. Usually, this is the number of slice encoding lines (nshots = nz / Rz), i.e., the number of slices divided by the total acceleration factor along z.

  • T1 (float | npt.ArrayLike) – Longitudinal relaxation time in milliseconds.

  • diff (str | tuple[str], optional) – Arguments to get the signal derivative with respect to. The default is None (no differentation).

  • inv_efficiency (float | npt.ArrayLike, optional) – Inversion efficiency map, default is 1.0.

  • M0 (float or array-like, optional) – Proton density scaling factor, default is 1.0.

  • TI – Inversion time in milliseconds. The default is 0.0.

  • chunk_size (int, optional) – Number of atoms to be simulated in parallel. The default is None.

  • device (str | torch.device, optional) – Computational device for simulation. The default is None (infer from input).

Returns:

  • sig (npt.ArrayLike) – Signal evolution of shape (...,).

  • jac (npt.ArrayLike) – Derivatives of signal wrt diff parameters, of shape (..., len(diff)). Not returned if diff is None.

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