Electromagnetics for Quantitative Magnetic Resonance Imaging
Stephen E. Russek, Karl F. Stupic, Joshua R. Biller, Kathryn E. Keenan, Elizabeth Mirowski
Magnetic Resonance Imaging (MRI) is based on radio frequency (RF) interrogation of the human body at frequencies between 40 MHz to 300 MHz. An RF transmitter excites proton spin precession and then, in a manner analogous to an RF ID tag, the protons precessional ring down reports back local information about its environment. Understanding the propagation of RF into the human body and how to manipulate and detect the nuclear spin probes provides a method to obtain quantitative measurements of tissue properties and disease states. Here, we present Bloch simulations describing nuclear spin dynamics and show how quantitative information can be obtained from MRI. We show how standard phantoms (imaging calibration structures), can be used to assess accuracy and variability of MRI-based measurements. We review MRI RF transmit and receive systems, the effect of complex electromagnetic material properties on images, and MRI- based measurement of electromagnetic properties of complex materials (e.g. living humans).
Electrostatic and Magnetic Phenomena: Particles, Macromolecules, Nanomagnetics