Basic Principles of Magnetic Resonance Imaging

Abstract

DOI: http://dx.doi.org/10.5915/17-1-12451

The basic concepts which are necessary to understand the physical principles of Nuclear Magnetic Resonance (NMR) imaging are presented. It is intended as a primer for the physicians or scientists who are addressing the topic of NMR for the first time. The basis of the NMR phenomena is described with introduction of the concepts of magnetic moment, magnetic resonance, net magnetic moment of an object, NMR excitation and NMR emission. The equipment necessary to observe these NMR properties is summarized as well as the procedures for basic NMR experiments. The major scanning methods are reviewed, and the principles of technique are discussed. With major emphasis on repeated free induction decay (RFTD) which yields proton image density, inversion-recovery (IRJ) which yields images weighted by tissue T-values, spin-echo (SE) which yields images weighted by tissue T{ values. Clinical applications of NMR imaging will be presented. Absence of known biological hazard, lack of moving parts, absence of ionizing radiation, and ability to measure multiple tissue parameters makes NMR the study of choice in many clinical situations particularly in early cancer diagnosis and in pathologic changes in the broad spectrum of disease within the brain. NMR's ability to create detailed tomographic images in any plane, with both anatomic detail and tissue specificity is revolutionizing diagnostic imaging. It has additional advantage of measuring metabolic processes in vivo which has great impact in understanding health and disease.