dcmri.signal_ss#
- dcmri.signal_ss(S0, R1, TR, FA, v=1, Fw=0, j=None, R10=None, noise_sdev=0)[source]#
Signal of a spoiled gradient echo sequence applied in steady state.
- Parameters:
S0 (float) – Signal scaling factor (arbitrary units).
R1 (array-like) – Longitudinal relaxation rates in 1/sec. For a tissue with n compartments, the first dimension of R1 must be n. For a tissue with a single compartment, R1 can have any shape. If R1 is a scalar, the result for a well-mixed tissue is returned.
TR (float) – Repetition time, or time between successive selective excitations, in sec.
FA (float) – Flip angle in degrees.
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.
R10 (float, optional) – R1-value where S0 is defined. If not provided, S0 is the scaling factor corresponding to infinite R10. Defaults to None.
noise_sdev (float, optional) – standard deviation of the signal noise. If this is non-zero, the signal is computed from the mean of the Rician distributions. A noise_sdev=0 has no effect.
- Returns:
Signal in the same units as S0
- Return type:
np.ndarray