Quantum-Mechanical Generalization of the Extended Phase Graph Method (QuaM-EPG) for the Simulation of Coupled Spin Systems Under SSFP Excitation

Zenon Starcuk jr. ¹, Jana Starcukova¹, Oliver Strbak¹, Danielle Graveron-Demilly²

A method suitable for the computer simulation of coupled spin systems under steady-state free precession (SSFP) excitation for fast MR spectroscopic imaging is described and demonstrated. The new method applies the principles of Hennig's Extended Phase Graph method to standard quantum mechanics employing the density matrix formalism, with relaxation described by the Redfield matrix. Thanks to the enhancement, balanced or nonbalanced (S+, S-) SSFP signals can be calculated. The calculation is basically a superstructure above the standard density-matrix simulation, no analytical preparation or complex programming are required. This approach can be useful also for analyzing SSFP with selective excitation.