Nuclear magnetic resonance simulation with radio frequency pulses

A Beginner's Guide to Bloch Equation Simulations of Magnetic Resonance Imaging Sequences

Nuclear magnetic resonance (nmr) concepts are rooted in quantum mechanics, but mr imaging principles are well described and more easily grasped using classical ideas and formalisms such as larmor precession and the phenomenological bloch equations.Still, carrying out numerical bloch equation simulations of the signal evolution can oftentimes supplement and enrich one s understanding.And though it may appear intimidating at first, performing these simulations is within the realm of every imager.The primary objective herein is to provide novice mr users with the necessary and basic conceptual, algorithmic and computational tools to confidently write their own simulator.Two regimes of bloch equation simulations are presented, the first which has no radiofrequency (rf) pulses, and the second in which radiofrequency pulses are applied.For the first regime, analytical solutions are given, whereas for the second regime, an overview of the computationally efficient, but often overlooked, rodrigues'
rotation formula is given.Various simulation conditions of interest and example code snippets are given and discussed to help demonstrate how straightforward and easy performing mr simulations can be.