The “Spin-3/2 Bloch Equation”: System matrix formalism of excitation, relaxation, and off-resonance effects in biological tissue

Abstract

Purpose: This work proposes “Spin-3/2 Bloch Equation” (SBE), a consolidated formalism for spin-3/2 dynamics in biological environments. The formalism encapsulates excitation, relaxation, and off-resonance with accessible matrix representation for a straightforward implementation with high computational efficiency. Theory: The SBE is derived using spherical tensor operators to encapsulate the spin-3/2 dynamics in biological systems in a single system matrix, a formalism akin to the well-known Bloch Equations (BE). Methods: Using the proposed SBE, simulations of three classical 23Na pulse sequences were performed to demonstrate the versatility and applicability of the model, returning the evol..