Image Formation by Induced Local Interactions: Examples Employing Nuclear Magnetic Resonance

An image of an object may be defined as a graphical representation of the spatial distribution of one or more of its properties as a result of interaction with a matter or radiation field characterized by a wavelength comparable to or smaller than the smallest features to be distinguished.

Abstract

AN image of an object may be defined as a graphical representation of the spatial distribution of one or more of its properties. Image formation usually requires that the object interact with a matter or radiation field characterized by a wavelength comparable to or smaller than the smallest features to be distinguished, so that the region of interaction may be restricted and a resolved image generated. In 1973, Paul Lauterbur described an imaging technique that removed the usual resolution limits due to the wavelength of the imaging field. He used two fields: one interacting with the object under investigation, the other restricting this interaction to a small region. Rotation of the fields relative to the object produces a series of one-dimensional projections of the interacting regions, from which two- or three-dimensional images of their spatial distribution can be reconstructed. Application of this technique as magnetic resonance imaging is now widespread.