How do MRI Scans Work?

HITACHI, Magnetic Resonance Imaging System, ECHELON OVAL,
HITACHI, Magnetic Resonance Imaging System, ECHELON OVAL, Credit: Wikimedia/Mj-bird

The eyes of doctors cannot penetrate the skin. Although many diseases can be diagnosed by accounting for the symptoms alone, some diseases need more sophisticated observation. This is where MRI scans come in handy. MRI stands for Magnetic Resonance Imaging. The MRI machine contains a large tube-shaped magnet, which produces a magnetic field. A magnetic field is a space around a magnet in which the effects of the magnet can be observed. When a patient is put inside the MRI machine, the magnetic field acts on the water molecules inside the human body.


The magnetic field changes the orientation of these water molecules. Then radio waves are pulsed through the body of the patient. These are the same type of waves that are used in mobile phones for communication. When these waves are passed through, the water molecules or other atoms are shifted out of position. On switching these radio waves off, the molecules quickly come back to their original position. This generates a radio signal that the imaging system uses to develop a 3D image. With the help of MRI scans, tumors in the brain and diseases in bone can be discovered. Liver and kidney diseases are also diagnosed with the help of MRI scans.

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