dcmri.signal_spgr#

dcmri.signal_spgr(S0, R1, T, TR, FA, TP=0.0, v=1, Fw=0, j=None, n0=0, R10=None) → ndarray[source]#

Signal of an SPGR sequence.

Parameters:

  • S0 (float) – Signal scaling factor (arbitrary units).

  • R1 (array-like) – Longitudinal relaxation rate in 1/sec.

  • T (float) – time since the first readout rf-pulse.

  • TR (float) – Repetition time, or time between successive selective excitations, in sec.

  • FA (array-like) – Flip angle in degrees.

  • TP (float, optional) – Time (sec) between the preparation pre-pulse and the first readout pulse. Defaults to 0.

  • v (array-like, optional) – volume fractions of the compartments. For a one-compartment tissue this is a scalar - otherwise it is an array with one value for each compartment. Defaults to 1.

  • Fw (array-like, optional) – Water flow between the compartments and to the environment, in units of mL/sec/cm3. Generally Fw must be a nxn array, where n is the number of compartments, and the off-diagonal elements Fw[j,i] are the permeability for water moving from compartment i into j. The diagonal elements Fw[i,i] quantify the flow of water from compartment i to outside. For a closed system with equal permeabilities between all compartments, a scalar value for Fw can be provided. Defaults to 0.

  • j (array-like, optional) – normalized tissue magnetization flux. j has to have the same shape as R1. Defaults to None.

  • n0 (array-like, optional) – initial relative magnetization at T=0. If this is a scalar, all compartments are assumed to have the same initial magnetization. Defaults to 0.

  • R10 (float, optional) – R1-value where S0 is defined. If not provided, S0 is the scaling factor corresponding to infinite R10. Defaults to None.

Raises:

ValueError – If TP is larger than TC.

Returns:

Signal in arbitrary units, of the same length as R1.

Return type:

np.ndarray