MRI stands for Magnetic resonance imaging. MRI is a technique that uses a magnetic field as well as radio waves to created detailed images of your tissue and organs inside your body.
Most MRI’s are large donut shaped magnets. There are some variations such as an Closed Bore, Open, Wide-Bore and open upright. When you lie inside an MRI machine, the magnetic field temporarily realigns your hydrogen atoms. Radio waves cause these aligned to produce vary faint signals which are used to create cross-sectional MRI images also called slices. These slices then are combined together.
The same images can also be used to create a 3D image that may be viewed from all different angles.