How does a MRI machine work ? | The Science behind MRI

                      Hey guys in this article, we'll try understanding how a MRI machine works, how does a MRI machine detects and display images of parts of our body like brain etc., 

 What is a MRI ?

                    MRI stands for Magnetic Resonance Imaging, it is medical imaging technique used in radiology to create detailed images of organs and tissues inside our body.

               MRI machine consists of mainly 3 components - the Magnet, Radiowaves and a Gradient. A computer is needed to display images.

 

               The tunnel that we see in the first image in which the patient is placed, is the magnet, that creates a strong magnetic field around the patient. The gradient (red color in the above fig) adjusts the magnetic field into smaller sections of different strengths to isolate specific body parts.

How does the MRI machine work ?

           Now to understand how MRI machine functions, let's first try to understand human body.

           The human body is full of water in it. Every molecule of water is made of two atoms of hydrogen and one atom of oxygen, which we know it as H₂O. 

           So when a person is placed inside the machine, these hydrogen atoms act as tiny magnets and are very sensitive to magnetic field.

          The water molecules inside us are moving randomly, but when a person is laid inside the machine in the presence of magnetic field, most of the water molecules start to move at same frequency as that of the magnetic field.

          The ones that don't move along the magnetic field are called Low Energy Molecules and these are the molecules on which MRI machine wants to focus on.

          Now, radiowaves are introduced through an antenna present inside the machine at a same frequency as that of a magnetic field, to pass through the person's body.

         These low energy molecules will now absorb energy through these radiations, that makes low energy molecules to start moving at the same frequency as that of the magnetic field.

         After a while, the machine stops sending the radiowaves and the water molecules that had just moved along the magnetic field after absorbing energy through these radiations will now release this energy and the antenna inside the machine will receive the signals sent by these molecules and is then sent to a powerful computer which uses an imaging software to translate the information into an image of an organ.

          By taking images of the body in each section of magnetic field, the computer produces a final 3D image of the organ which doctors can analyze to make further diagnosis. An example of how a MRI scan looks.

Few Facts...

• The first successful MRI scan was performed on a live human patient on July 3rd, 1977.

• Unlike X-ray or CT scan, MRI does not use ionizing radiation. This makes MRI a popular alternative to scans that use ionizing radiations.

• MRI was originally called NMRI (Nuclear MRI), but "nuclear" word was dropped due to negative associations. 

                

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