simRf

Simulates the effect of an RF pulse on nuclear magnetization using a quaternion-based rotation formalism. It takes a Pulseq RF pulse definition as input and returns the resulting magnetization components, frequency axis, and refocusing efficiency.

Syntax

function [Mz_z,Mz_xy,F,ref_eff,Mx_xy,My_xy]=simRf(rf,rephase_factor,prephase_factor)

Calling Pattern

mr.simRf(...)

Parameters

Required Parameters

Name	Type	Description	Example	Units
rf	struct	A Pulseq RF pulse structure. This structure contains all the parameters defining the RF pulse, such as amplitude, duration, shape, frequency, phase, etc.	Pulseq RF pulse structure (created using Pulseq functions)

Optional Parameters

Name	Type	Default	Description	Example
rephase_factor	double	0	A factor used to correct the phase of the magnetization, particularly important for slice-selective excitation pulses. It accounts for the timing difference between the pulse's center and its duration. Valid values: Any real number	0.004
prephase_factor	double	0	An experimental parameter used for simulating refocusing pulses or spoiling. It allows for additional phase adjustments beyond the rephase factor. Valid values: Any real number	0

Returns

Output	Type	Description
Mz_z	double	The z-component of the magnetization after the RF pulse, assuming initial magnetization along the z-axis.
Mz_xy	double	The xy-component of the magnetization after the RF pulse, assuming initial magnetization along the z-axis.
F	double	The frequency axis in Hz.
ref_eff	double	The refocusing efficiency of the pulse as a complex number. The magnitude reflects the refocusing and the phase is related to the effective phase of the RF pulse.
Mx_xy	double	The xy-component of the magnetization after the RF pulse, assuming initial magnetization along the x-axis.
My_xy	double	The xy-component of the magnetization after the RF pulse, assuming initial magnetization along the y-axis.

Examples

% RF profile validation for excitation pulse
[M_z90, M_xy90, F2_90] = mr.simRf(rf_ex);
sl_th_90 = mr.aux.findFlank(F2_90(end:-1:1)/gz.amplitude, abs(M_xy90(end:-1:1)), 0.5) - mr.aux.findFlank(F2_90/gz.amplitude, abs(M_xy90), 0.5);

% RF profile validation for refocusing pulse
[M_z180, M_xy180, F2_180, ref_eff] = mr.simRf(rf_ref);
sl_th_180 = mr.aux.findFlank(F2_180(end:-1:1)/g_ref.amplitude, abs(ref_eff(end:-1:1)), 0.5) - mr.aux.findFlank(F2_180/g_ref.amplitude, abs(ref_eff), 0.5);

% Basic RF simulation
[Mz_z, Mz_xy, F, ref_eff, Mx_xy, My_xy] = mr.simRf(rf_pulse_struct);

See Also

mr.calcRfBandwidth