dcmri.signal_free#

dcmri.signal_free(S0, R1, T, FA, v=1, Fw=0, j=None, n0=0, R10=None)[source]#

Signal with readout after a free recovery.

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.

  • T (float) – time to center of k-space

  • FA (float) – flip angle

  • 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.

Returns:

Signal in the same units as S0 and with the same dimensions as R1.

Return type:

np.ndarray