Nuclear magnetic resonance imaging (MRI).

This article discusses the basic concepts of Magnetic Resonance Imaging (MRI) with the intention to introduce the subject to uninitiated. The MRI technique is a powerful noninvasive probe of the body's internal anatomy. In MRI, the images are produced not by X-rays, but through the use of non-ionizing radiowaves that stimulate transitions between spin states of nuclei in a magnetic field when passed through the body. The time required for the nucleus to return to equilibrium gives information about the environment of that nucleus. In this way tissue abnormalities can be determined in vivo. This article covers the basis of MRI phenomena, the concept of magnetic moment of the sample, NMR exalation and emission and the equipment necessary to observe these NMR properties. The primary agents used to increase tissue contrast in MRI are also mentioned. Finally the importance and prospects of this technique in Pakistan have been discussed.