IRbSSFPSimulator

class torchsim.simulators.IRbSSFPSimulator(*args, **kwargs)

Bases: Simulator

Recovery from an inversion under a balanced SSFP train.

After an alpha/2 preparation the balanced train drives the magnetization along one exponential towards the bSSFP steady state, at a rate that mixes R1 and R2 by the flip angle [1], so the recovery curve yields T1, T2 and the proton density together. The signal is read at a series of times after the inversion; inv_efficiency scales the magnetization the recovery starts from.

References

[1]

Schmitt, P., Griswold, M. A., Jakob, P. M., et al., “Inversion recovery TrueFISP: quantification of T1, T2, and spin density”, Magnetic Resonance in Medicine 51.4 (2004), pp. 661-667. https://doi.org/10.1002/mrm.20058

Examples

import torch
from torchsim.simulators import IRbSSFPSimulator

sequence = IRbSSFPSimulator(flip=45.0, TI=4.5 * torch.arange(1000))
signal = sequence.simulate(T1=1000.0, T2=(50.0, 100.0))
print(signal.shape)

torch.Size([2, 1000])

Methods

bind	This simulator with more fixed on it, values or settings alike.
describe	Return the description this protocol plays.
evaluate	Evaluate the closed form, no state machine and no description.
from_description	Return a simulator over a stream someone else assembled.
from_pulseq	Return a simulator over one repetition of a Pulseq sequence.
jacobian	Return the signal and its derivative with respect to diff.
layout	Return the operators of one repetition, in the order they play.
played	Return the protocol as it will be laid out.
repetition_s	Return how long one repetition lasts, given what the layout played.
simulate	Return the recorded signal.

evaluate(properties, **sequence)

Evaluate the closed form, no state machine and no description.