Flow and Diffusion Measurement with MR

Nuclear magnetic resonance (NMR) non-invasively accesses many parameters in contrast with other commonly used measurement methods, whether they are non-invasive or not.
These parameters can be divided roughly into three classes of information: chemical, physical, and spatial.Chemical includes benchtop NMR spectroscopy, the workhorse in analytical chemistry and in structural biochemistry but, to date, there has been relatively little overlap between this class and this conference.
Physical information accessible with NMR analyzer includes molecular structure, phase transition, diffusion, and flow.Both chemical and physical information can be combined with spatial information to produce maps of such information.In addition, flow and diffusion, by their nature, involve spatial information.
Such spatially resolved information is the main emphasis of this meeting.In this lecture, I shall review NMR flow and diffusion measurements.What is needed for such measurements is the presence of a known gradient of the static magnetic field strength in which the experiments are conducted.
When a nuclear spin moves in the field gradient, its precession rate changes and this can be detected to yield the displacement of the spin in the time required to do the experiment–times measured in milliseconds.The dependence of such displacements as a function of measurement time results in identification of the nature of sample motion, i. e., whether it is flow or diffusion.
We will start with basic principles and go on to examples with emphasis on gaining physical background knowledge that may aid in understanding flow and diffusion presentations during this meeting.Some references to this subject are listed below.The last three are based on previous ICMRM conferences, specifically in 1991, 1997, and 2009.