Simulate spin dynamics for spin-3/2 nuclei (23Na, 7Li, 39K, etc.) using irreducible spherical tensor operators (ISTOs). This is useful for modelling quadrupolar relaxation and multiple quantum coherences.
The code implements the model described here:
A model for the dynamics of spins 3/2 in biological media: signal loss
during radiofrequency excitation in triple-quantum-filtered sodium MRI
I. Hancua, J. R. C. van der Maarelb and F. E. Boada
JMR 147, 2000, p179-191
http://www.ncbi.nlm.nih.gov/pubmed/11097809
The longitudinal recovery modelled is described here:
Sodium Imaging Optimization Under Specific Absorption Rate Constraint
Robert Stobbe and Christian Beaulieu
Magnetic Resonance in Medicine 59:345–355 (2008)
http://onlinelibrary.wiley.com/doi/10.1002/mrm.21468/abstract
There is a little more detail in Rob's PhD thesis here
Sodium MRI optimization for the human head with application to acute stroke
University of Alberta, 2010
https://www.bac-lac.gc.ca/eng/services/theses/Pages/item.aspx?idNumber=606497388
This paper is also helpful to understand the modelling:
Thermal relaxation and coherence dynamics of spin 3/2
I. Static and fluctuating quadrupolar interactions in the multipole basis
J. R. C. van der Maarel
Concepts Magn Resn A 19A(2), 2003, pp97-116
http://onlinelibrary.wiley.com/doi/10.1002/cmr.a.10087/abstract