MRI in One Dimension and with No Relaxation: A Gentle Introduction to a Challenging Subject

Introduction to Magnetic Resonance Imaging. MRI is surely the most celebrated of the newer imaging modalities. It can display high-quality slice and 3D images of both the anatomy and the physiology of tissues, organs, and vessels with contrast among radiologically similar soft tissues that is positively brilliant. Spatial resolution, moreover, is in the sub-millimeter range. And like US, it does all of this with no exposure of patient or staff to ionizing radiation. The chapter introduces the process of nuclear magnetic resonance (NMR) of the nuclei of the hydrogen atoms (i.e., isolated protons) of the water, lipid, and other molecules in tissues, which forms the biophysical basis for MRI. It then demonstrates a real example of spin-echo proton-density (PD) MRI for a particularly simple case, that of a one-dimensional ‘patient’ comprised of slices containing different amounts of water, in the absence of so-called relaxations effects. The chapter concludes with a description of MRI equipment, QA, and safety issues.