Introduction

Abstract

The universe is full of spinning objects – galaxies, suns, planets, weather patterns, pink ballerinas, footballs, atoms, and subatomic particles to name a few. It is remarkable not that humans invented the wheel, but that they took so long. Bacteria did it millions of years earlier. However, humans are remarkable for their powers of observation, virtual memory (recording), and analysis. The wheel of the mind, a much more remarkable invention than the wheel of the donkey cart or the Ferrari, is mathematics. Just as recording extends human memory beyond its physical limitations, mathematics extends human analysis into regions inconceivable to the mind – complex numbers being a particularly apposite example. If you use mathematics to describe the appearance of a spinning object the answer is a sinusoid. If you use mathematics to describe the behavior of the energy used for medical imaging the answer is a sinusoid. In MRI the spinning object and the energy used for imaging are inseparable. Joseph Fourier showed we can go even further than this – every measurable thing, including medical images, can be described with sinusoids. This simple concept, once apprehended, can be seen to bind the multiplicity of medical imaging methods into one whole.