Mechanism
As the Radiology Info website explains, the MRI machine is essentially a gigantic magnet. The molecules and atoms within your body have subatomic particles called protons, which spin around on a subatomic level. These protons are most relevant for water because water contains two hydrogen ions, which are essentially protons. When a strong magnetic field is applied to the body, the protons in the water emit their own miniature magnetic fields. These minor signals can be detected by instruments within the MRI machine and sent to a computer, which can interpret the signals to form an image of the tissues inside the body.
Procedure
For an MRI, the patient needs to change into a hospital gown and remove any metallic objects. This is because they can be attracted to the magnetic field that the MRI machine produces. As the Mayo Clinic explains, the patient then lies down on a movable table, which slides the patient into a big tunnel that is open at both ends. This is the actual MRI machine. The patient will lie down in the machine for approximately an hour while the machine takes measurements from different parts of the body and at different angles. It is important to lie still to avoid blurring the images.
Results and Interpretation
MRI machines generate thin cross sections of the appearance of the inside of the body, often based on water content. In general, a radiologist will then look at several cross sections that have been taken very near each other to look for dead tissue, unusual bulges or spaces in the tissue, as well as for any obvious tissue damage. Sometimes, a computer can assimilate the cross sections yielded by the MRI machine into a full 3-D model of the inside of the patient, though this technology can be expensive and is not always used.
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