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EPG-isochromat

EPG vs isochromat-summation simulations

This repository contains Matlab code for implementing EPG and isochromat-summation simulations of FSE and SPGR pulse sequences. The methods are compared and shown to be equivalent under certain conditions. The EPG and isochromat-summation code can be used for any purpose.

This project was first presented as an ISMRM abstract at the 2016 conference and has since been written up as a full paper. For details of the ISMRM abstract version, please see this page

The following document describes the full version of the code, which has been written up and submitted for peer reviewed publication.

Author: Shaihan Malik (twitter: @shaihanmalik), June 2016

Code Description

The results in the paper are divided into 3 experiments, which are generated from three different scripts:

  • Experiment 1 concerns transient SPGR simulations with differing numbers of isochromats and is run by SPGR_runme_1.m
  • Experiment 2 concerns FSE simulations with different numbers of isochromats, and is run by FSE_runme.m
  • Experiment 3 concerns steady-state SPGR simulations with and without considering diffusion effects, and is run by SPGR_runme_2.m

The core functions to simulate SPGR and FSE sequences respectively are SPGR_isochromat_sim.m and FSE_isochromat_sim.m for isochromat summation and SPGR_EPG_sim.m and FSE_EPG_sim.m for Extended Phase Graphs. These have the same underlying syntax, and angles are always in radians, times in ms.

Detailed description of implementations

A detailed supporting methods document has been written as part of this work. You can download it here. Please get in touch with any comments or suggestions