What is MRI test?

MRI TechnologyUnpaired nuclei in an atom have a resultant spin. We apply a strong magnetic field, so that they align themselves (in their own ways!). Then we blast them with a radio frequency pulse to make them feel dizzy. However, the nuclei (proton) though perturbed, they revert back to their 'original' configuration; releasing an RF pulse that is detected. This 'pulse' is interpreted and visualized by the radiologists.

The above is an oversimplification, since in addition to this, we need to know how the nuclei 'relax': T1 & T2 relaxation.

You may learn more about this (in layman's as well as professional terms) in my blog article: Understanding the Basic Principles of Nuclear Magnetic Resonance Imaging. Please see the related link.

There's much more to it (e.g. relaxation) which I've also covered.