Phase relaxed method for CPMG excitation pulses. The method was presented at the ISMRM conference in 2014 (abstract here) and as a full paper in 2016. This repo contains Matlab code for implementing 2D or 3D pulse designs.
Shaihan Malik, July 2015
Code is available as a release including binary files (Matlab .mat files) containing B1 and B0 field maps. Please see the releases page for more.
A persistent citeable version of release 1.0 is available:
example1_spiral2D.m and example2_shells3d.m are Matlab scripts that run through 2D spiral and 3D 'shells' k-space trajectory versions of the pulse design. They rely on B1 and B0 maps available on the releases page.
The code is dependent on the reverse-GIRF project and on mcgls.m. See next section.
This code is provided freely under the terms of the MIT license. Please cite appropriately.
The pulse design method uses the time-optimal gradient design method (Lustig et al, 2008) and VERSE based pulse design method (Lee et al, 2009). An implementation of the Lustig 2008 method (minTimeGradient) is available here.
We have extended Lustig's code to implement (Lee et al, 2009) and also a gradient impulse response function (GIRF) based correction for non-ideal gradient systems. The reverse-GIRF project contains all necessary code including Lustig's original source (with permission). Please take note of the citations suggested in the readme.
Least squares minimizations are solved using the multi-shift approach from van den Eshof et al, 2003. We used mcgls.m that can be downloaded from here.
If this is unavailable, any other method for least squares solutions of non-square matrices can be used. We have found LSQR (matlab implementation) to work well in the past.