Simulators

The sequences that ship with TorchSim. A constructor takes the keywords simulate() takes and fixes them, so a sequence and the tissue it is being asked about are written down together and what is left to give at the call is whatever is actually varying.

Closed form

Signals that have an analytic expression, evaluated in one pass.

torchsim.simulators.bSSFPSimulator	The balanced SSFP steady state, read at the echo time.
torchsim.simulators.SPGRSimulator	The spoiled gradient-echo steady state, read at the echo time.
torchsim.simulators.MP2RAGESimulator	Two gradient-echo blocks read at two inversion times, in closed form.
torchsim.simulators.InversionRecoverySimulator	Longitudinal recovery from an inversion, read at a series of delays.
torchsim.simulators.MultiEchoSimulator	Transverse decay, read at a series of echo times.
torchsim.simulators.DoubleAngleSimulator	Excitation at a series of flip angles, scaled by the transmit field.
torchsim.simulators.SpinEchoSimulator	A spin echo repeated every TR, optionally behind an inversion.
torchsim.simulators.LookLockerSimulator	Recovery from an inversion under a spoiled train of small flip angles.
torchsim.simulators.MOLLISimulator	Look-Locker readout blocks separated by free recovery, after one inversion.
torchsim.simulators.IRbSSFPSimulator	Recovery from an inversion under a balanced SSFP train.
torchsim.simulators.HSFPSimulator	A balanced train whose flip angle varies slowly, in the hybrid state.
torchsim.simulators.MultiGradientEchoSimulator	Water and fat, dephasing and decaying across a gradient-echo train.
torchsim.simulators.IRMultiGradientEchoSimulator	A multi-gradient-echo train read at a series of inversion times.
torchsim.simulators.DiffusionSimulator	Attenuation by Gaussian diffusion, at a series of b-values.
torchsim.simulators.LorentzianSimulator	A Z-spectrum as equilibrium minus one Lorentzian line per pool.
torchsim.simulators.ASLSimulator	The label-control difference of arterial spin labelling, over time.

State machine

Trains that have to be played out, run on the extended phase graph engine.

torchsim.simulators.FSESimulator	A refocused echo train, sampled at every echo.
torchsim.simulators.HyperechoSimulator	A refocused train mirrored about a central refocusing pulse.
torchsim.simulators.StimulatedEchoSimulator	Three pulses, sampled at the spin echo of the first two and at the stimulated echo.
torchsim.simulators.MPRAGESimulator	An inversion followed by a spoiled train, sampled at the k-space centre.
torchsim.simulators.MPnRAGESimulator	An inversion followed by a spoiled gradient-echo train, every shot read.
torchsim.simulators.MRFSimulator	An inversion, then a variable flip-angle train whose readouts wind on.
torchsim.simulators.FLASHSimulator	A spoiled gradient-echo train from equilibrium, optionally inverted first.
torchsim.simulators.TrueFISPSimulator	A balanced SSFP train from equilibrium, optionally inverted first.
torchsim.simulators.fmSSFPSimulator	A balanced SSFP train whose RF frequency is swept through one passband per sweep.
torchsim.simulators.CESTSimulator	A Z-spectrum simulated through a train of saturation pulses, pool by pool.

Functional wrappers

The *_sim functions are convenience calls for a subset of the shipped simulators: protocol and tissue go into one function call, with an optional Jacobian. They are not a second extension API. New sequence families are implemented as Simulator subclasses, so they can use both an offline layout() and the same handlers when a Pulseq/MRD description arrives from a scanner.

Prefer the simulator classes whenever the same sequence is reused, bound to a protocol, passed to an estimator/reconstruction/design object, or constructed from a description. The wrappers remain useful for compact one-off calls.

Analytical

torchsim.bssfp_sim	Balanced steady-state free-precession simulator wrapper.
torchsim.spgr_sim	SPoiled Gradient Recalled echo simulator wrapper.

Iterative

torchsim.fse_sim	Fast Spin Echo simulator wrapper.
torchsim.mprage_sim	MPRAGE simulator wrapper.
torchsim.mp2rage_sim	MP2RAGE simulator wrapper.
torchsim.mpnrage_sim	MPnRAGE simulator wrapper.
torchsim.mrf_sim	SSFP MR Fingerprinting simulator wrapper.