makeExtendedTrapezoidArea¶

Generates the shortest possible extended trapezoid gradient waveform with a specified area, starting and ending with optionally non-zero gradient values. The function uses optimization techniques (fminsearch) to find the optimal gradient amplitude and plateau duration to achieve the desired area while respecting system limits (maximum gradient amplitude and slew rate).

Syntax¶

function [grad, times, amplitudes] = makeExtendedTrapezoidArea(channel, Gs, Ge, A, sys)

Calling Pattern¶

mr.makeExtendedTrapezoidArea(...)

Parameters¶

Required Parameters¶

Name	Type	Description	Example	Units
`channel`	char	The gradient channel ('x', 'y', or 'z') for which to create the waveform.	`'x'`
`Gs`	double	The starting gradient amplitude.	`100`	Hz/m
`Ge`	double	The ending gradient amplitude.	`100`	Hz/m
`A`	double	The desired area of the extended trapezoid.	`0.1`	1/m
`sys`	struct	A structure containing system parameters. Must include fields like 'maxSlew' (maximum slew rate in Hz/m/s), 'gradRasterTime' (gradient raster time in seconds), and 'maxGrad' (maximum gradient amplitude in Hz/m).	`mr.opts()`

Returns¶

Output	Type	Description
`grad`	struct	A Pulseq gradient waveform structure containing the generated extended trapezoid.
`times`	double	A vector of time points (in seconds) defining the waveform.
`amplitudes`	double	A vector of gradient amplitudes (in Hz/m) corresponding to the time points.

Examples¶

% Create refocusing gradient with spoiler areas
g_ref_pre = mr.makeExtendedTrapezoidArea(g_ref.channel, 0, g_ref.amplitude, spAz+gzr.area, system);
g_ref_post = mr.makeExtendedTrapezoidArea(g_ref.channel, g_ref.amplitude, 0, spAz, system);

% Slice spoiling gradient starting from zero
gzSpoil = mr.makeExtendedTrapezoidArea('z', 0, gz.amplitude, sp_area_needed, sys);

% Readout spoiling gradient with amplitude transition
groSp = mr.makeExtendedTrapezoidArea(gro.channel, gro.amplitude, 0, deltak(ax.n1)/2*N(ax.n1)*ro_spoil, sys);