TEXT
MRI is a medical imaging device commonly used to examine the soft tissues of the human body.
Let’s meet the machine. The key components are: The magnet, radio waves, the gradient, and a computer.
Our bodies are made up of 60% water, and water is magnetic. Each of the billions of water molecules inside us consists of an oxygen atom bonded to two hydrogen atoms. We know it as H2O.
Small parts of the hydrogen atoms act as tiny magnets and are very sensitive to magnetic fields.
MRI stands for Magnetic Resonance Imaging, and a MRI scanner is one of the main diagnostic tools that doctors use do to examine inside our bodies.
The first step in taking an MRI scan is to use a big magnet to produce an unified magnetic field around the patient.
The gradient adjusts the magnetic field into smaller sections at different magnetic strengths, to isolate specific body parts, for example the brain.
Normally the water molecules inside us are arranged randomly, but when we lie inside a magnetic field, most of our water molecules move at the same rhythm or frequency as the magnetic field. The ones that don’t move along the magnetic field are called low energy water molecules.
To create an image of a body part, for example the brain, the machine focuses on the low energy water molecules.
Radio waves move at the same rhythm or frequency as the magnetic fields in an MRI machine. By sending radio waves that match or resonate with the magnetic field, the water molecules absorb the energy they need to move alongside the magnetic field .
When the machine stops emitting radio waves, the water molecules that had just moved along the magnetic field release the energy they had absorbed and go back to their position; this movement is detected by the MRI machine and a signal is sent to a powerful computer which uses imaging software to translate the information into an image of the body.
By taking image of the body in each section of the magnetic field the machine produces a final 3- dimensional image of the organ which doctors can analyze to make a diagnosis.
QUESTIONS
- What is a MRI machine used for?
- Name the components of an MRI machine.
- Which components in the molecules in our body are sensitive to magnetic fields?
- What is the function of the Gradient?
- The MRI machine focuses on which water molecules to create an image of our body?
- What happens to some water molecules in our body when the MRI stops emitting radio waves?