makeGaussPulse¶

Generates a Gaussian RF pulse, optionally with slice-selective gradients. The function creates a Gaussian RF pulse with specified flip angle and duration. It allows for adjustments in frequency and phase offsets (in Hz and radians, or as a percentage of the Larmor frequency in ppm), and includes options for apodization and precise control over bandwidth and time-bandwidth product. Additionally, it can generate slice-selective gradients (gz) and corresponding refocusing gradients (gzr), given slice thickness and gradient limits (maxGrad, maxSlew).

Syntax¶

function [rf, gz, gzr, delay] = makeGaussPulse(flip,varargin)

Calling Pattern¶

mr.makeGaussPulse(...)
mr.makeGaussPulse('ParameterName', value, ...)

Parameters¶

This function accepts both positional parameters and name-value pairs.

Required Parameters¶

Parameter Name	Value Type	Description	Example	Units
`flip`	double	Desired flip angle of the RF pulse.	`pi/2`	radians

Name-Value Pair Arguments¶

Parameter Name (string)	Value Type	Default	Description	Example
`system`	struct	`[]`	Pulseq system structure containing hardware parameters (e.g., from mr.opts()). If empty, uses default system parameters.	`mr.opts()`
`duration`	double	`0`	Duration of the RF pulse. (Units: seconds)	`0.004`
`freqOffset`	double	`0`	Frequency offset of the RF pulse in Hz. (Units: Hz)	`100`
`phaseOffset`	double	`0`	Phase offset of the RF pulse in radians. (Units: radians)	`pi/4`
`freqPPM`	double	`0`	Frequency offset specified in parts per million (ppm) relative to the Larmor frequency. Useful for fat saturation. (Units: ppm)	`-3.3`
`phasePPM`	double	`0`	Phase offset specified in parts per million (ppm) relative to the Larmor frequency. (Units: ppm)	`0`
`timeBwProduct`	double	`3`	Time-bandwidth product of the Gaussian pulse.	`4`
`bandwidth`	double	`0`	Bandwidth of the RF pulse in Hz (overrides timeBwProduct if specified). (Units: Hz)	`1000`
`apodization`	double	`0`	Apodization parameter (0 for no apodization, 1 for full Hamming window).	`0.5`
`centerpos`	double	`0.5`	Position of the pulse center (0 to 1, where 0 is the beginning and 1 is the end).	`0.7`
`maxGrad`	double	`0`	Maximum gradient amplitude for slice selection. (Units: Hz/m)	`300`
`maxSlew`	double	`0`	Maximum gradient slew rate for slice selection. (Units: Hz/m/s)	`100000`
`sliceThickness`	double	`0`	Thickness of the slice for slice selection. (Units: meters)	`0.005`
`delay`	double	`0`	Delay before the pulse. (Units: seconds)	`0.001`
`dwell`	double	`0`	RF pulse dwell time. If 0, it uses the system's default rfRasterTime. (Units: seconds)	`0.000002`
`use`	char	`'u'`	Specifies the intended use of the RF pulse, for k-space calculation. Valid values: mr.getSupportedRfUse()	`'excitation'`

Returns¶

Output	Value Type	Description
`rf`	struct	Pulseq RF pulse definition.
`gz`	struct	Pulseq slice selection gradient definition.
`gzr`	struct	Pulseq slice refocusing gradient definition.
`delay`	double	calculated delay

Examples¶

% Create excitation pulse for ZTE/UTE sequences
rf = mr.makeGaussPulse(alpha*pi/180, 'Duration', rf_duration, 'timeBwProduct', 3, 'system', sys, 'use', 'excitation');

% Create fat saturation pulse with frequency offset
rf_fs = mr.makeGaussPulse(110*pi/180, 'system', lims, 'Duration', 8e-3, ...
    'bandwidth', abs(sat_freq), 'freqPPM', sat_ppm, 'use', 'saturation');

% Create water suppression pulses with different flip angles
for i=1:3
    rf_ws(i) = mr.makeGaussPulse(ws_fa(i) * pi / 180, 'system', system, ...
        'duration', ws_rf_dur, 'bandwidth', ws_rf_bw, 'use', 'saturation');
end