makeBlockPulse¶

Generates a block RF pulse with optional slice-selective capabilities. The function creates a Pulseq RF pulse object defining the characteristics of the pulse, including amplitude, duration, frequency and phase offsets. It can calculate the duration based on either the provided bandwidth or time-bandwidth product. It also handles optional parameters for slice selection (gradients) and returns both the RF pulse and a delay object to account for ringdown time.

Syntax¶

function [rf, delay] = makeBlockPulse(flip,varargin)

Calling Pattern¶

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

Parameters¶

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

Required Parameters¶

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

Name-Value Pair Arguments¶

Parameter Name (string)	Value Type	Default	Description	Example
`system`	struct	`[]`	System parameters structure (e.g., mr.opts()). Provides parameters like rfRasterTime, rfDeadTime, rfRingdownTime needed for pulse generation. If empty, default system parameters are used.	`mr.opts()`
`duration`	double	`0`	Duration of the RF pulse. If 0, it will be calculated from bandwidth or timeBwProduct. (Units: seconds)	`0.004`
`freqOffset`	double	`0`	Frequency offset of the RF pulse (Hz). (Units: Hz)	`100`
`phaseOffset`	double	`0`	Phase offset of the RF pulse (radians). (Units: radians)	`pi/4`
`freqPPM`	double	`0`	Frequency offset in parts per million (ppm) relative to the Larmor frequency. Can be used in addition to freqOffset. (Units: ppm)	`10`
`phasePPM`	double	`0`	Phase offset in parts per million (ppm) relative to the Larmor frequency. Can be used in addition to phaseOffset. (Units: ppm)	`5`
`timeBwProduct`	double	`0`	Time-bandwidth product of the RF pulse. If greater than zero, duration is calculated as timeBwProduct/bandwidth.	`1`
`bandwidth`	double	`0`	Bandwidth of the RF pulse (Hz). If greater than zero, duration is calculated as 1/(4*bandwidth). (Units: Hz)	`2500`
`maxGrad`	double	`0`	Maximum gradient amplitude for slice selection (Hz/m). (Units: Hz/m)	`50e6`
`maxSlew`	double	`0`	Maximum gradient slew rate for slice selection (Hz/m/s). (Units: Hz/m/s)	`200e6`
`sliceThickness`	double	`0`	Slice thickness for slice selection (meters). (Units: meters)	`0.005`
`delay`	double	`0`	Additional delay after the RF pulse (seconds). (Units: seconds)	`0.001`
`use`	char	`'u'`	Specifies the pulse type; affects k-space trajectory calculation. Must be one of mr.getSupportedRfUse(). Valid values: mr.getSupportedRfUse()	`'excitation'`

Returns¶

Output	Value Type	Description
`rf`	struct	Pulseq RF pulse object containing the generated RF pulse parameters.
`delay`	struct	Pulseq delay object accounting for RF ringdown time.

Examples¶

% Create 90-degree hard pulse for FID sequence
rf = mr.makeBlockPulse(pi/2, 'Duration', 0.3e-3, 'system', system, 'use', 'excitation');

% Create short excitation pulse for 3D GRE
[rf, rfDelay] = mr.makeBlockPulse(8*pi/180, sys, 'Duration', 0.2e-3, 'use', 'excitation');

% Create 180-degree refocusing pulse for spin echo
rf180 = mr.makeBlockPulse(pi, lims, 'Duration', 500e-6, 'use', 'refocusing');