bSSFPModel

bSSFPModel#

class torchsim.models.bSSFPModel(diff=None, chunk_size=None, device=None, *args, **kwargs)[source]#

Bases: AbstractModel

bSSFPModel transverse signal at time TE after excitation.

This class models the transverse magnetization signal generated by the balanced steady state free precession (bSSFP) sequence, calculated at echo time (TE) following RF excitation.

Parameters:

  • diff (str | tuple[str] | None)

  • chunk_size (int | None)

  • device (str | device | None)

set_properties(T1, T2, M0=1.0, B0=0.0, chemshift=0.0):

Set tissue and system-specific properties for the SPGR model.

set_sequence(flip, TR, TE=None, phase_inc=180.0):

Set sequence parameters including flip angle, repetition time (TR), echo time (TE) and RF phase increment.

_engine(T1, T2, TR, TE, flip, M0=1.0, field_map=0.0, delta_cs=0.0):

Compute the bSSFP signal for given tissue, sequence, and field parameters.

Examples

from torchsim.models import bSSFPModel

model = bSSFPModel()
model.set_properties(T1=1000, T2=100)
model.set_sequence(flip=60.0, TR=10.0, TE=5.0)
signal = model()

Methods

__init__

Initialize the model with automatic parameter segregation and engine setup.

forward

Get forward method.

jacobian

Get Jacobian method.

set_properties

Set tissue and system-specific properties for the SPGR model.

set_sequence

Set sequence parameters for the SPGR model.
set_properties(T1, T2, M0=1.0, B0=0.0, chemshift=0.0)[source]#

Set tissue and system-specific properties for the SPGR model.

Parameters:

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

  • T2 (float | npt.ArrayLike) – Transverse relaxation time in milliseconds.

  • M0 (float | npt.ArrayLike, optional) – Proton density scaling factor, default is 1.0.

  • B0 (float | npt.ArrayLike, optional) – Frequency offset map in Hz, default is 0.0.

  • chemshift (float | npt.ArrayLik, optional) – Chemical shift in Hz, default is 0.0.

set_sequence(flip, TR, phase_inc=180.0, TE=None)[source]#

Set sequence parameters for the SPGR model.

Parameters:

  • flip (float | npt.ArrayLike) – Flip angle in degrees.

  • TR (float | npt.ArrayLike) – Repetition time in milliseconds.

  • phase_inc (float, optional) – Linear phase-cycle increment in degrees. The default is 180.0

  • TE (float | npt.ArrayLike, optional) – Echo time in milliseconds. The default is None (i.e., TR/2).

static _engine(T1, T2, TR, TE, flip, M0=1.0, B0=0.0, chemshift=0.0, phase_inc=180.0)[source]#

Core computational function for the model.

Parameters: