LookLockerSimulator

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

Bases: Simulator

Recovery from an inversion under a spoiled train of small flip angles.

Each pulse tips a little of the longitudinal magnetization away, so the recovery runs towards a steady state below equilibrium at the apparent rate R1* = R1 - ln(cos a) / TR [1], and each readout records the longitudinal magnetization just ahead of its pulse, times sin a. Reading the recovery at a set of times after the inversion gives T1, the flip angle’s efficiency B1 and the proton density together.

References

[1]

Look, D. C., Locker, D. R., “Time saving in measurement of NMR and EPR relaxation times”, Review of Scientific Instruments 41.2 (1970), pp. 250-251. https://doi.org/10.1063/1.1684482

Examples

import torch
from torchsim.simulators import LookLockerSimulator

sequence = LookLockerSimulator(flip=6.0, TR=4.0, TI=4.0 * torch.arange(500))
signal = sequence.simulate(T1=(800.0, 1400.0))
print(signal.shape)

torch.Size([2, 500])

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.