Magnetic resonance imaging (MRI) scanner uses a magnetic field and pulses of radio wave energy to make pictures of organs and structures that are inside the body. MRI scanners use strong magnetic fields, electric field gradients, and radio waves to generate images of the organs in the body. MRI is widely used in hospitals and clinics for medical diagnosis, staging of disease and follow-up without exposing the body to ionizing radiation. To perform a study, the person is positioned within an MRI scanner that forms a strong magnetic field around the area to be imaged. In most medical applications, protons (hydrogen atoms) in tissues containing water molecules create a signal that is processed to form an image of the body. The major components of an MRI scanner are: the main magnet, which polarizes the sample, the shim coils for correcting inhomogeneities in the main magnetic field, the gradient system which is used to localize the MR signal and the RF system, which excites the sample and detects the resulting NMR signal. The whole system is controlled by one or more computers.