Magnetic Resonance Imagine is usually referred to as MRI. MRI devices are large machines which look like large tubes; they have a big magnet in the circular area. The patient is laid down on a table, which then moves into the tube.
Extremely powerful radio waves, between 10,000 and 30,000 times stronger than earth’s magnetic field are sent through the body. They force the nuclei of the body’s atoms into a new position. As they move back into their original place they emit radio waves. A scanner gathers these signals, sends them to a computer which turns them into an image on a screen. The images are based on where the incoming signals are coming from and how strong they are.
The human body is made up mostly of water. Water has hydrogen atoms. That is why hydrogen atoms are most commonly used to create an MRI scan. MRI scanners can create pictures of nearly any part of the body. Bones have the least number of hydrogen atoms, so they come out dark in the pictures, while blood or tissue (especially fatty tissue) look much brighter.
The timing of the radiowave pulses may be altered so that more data may be gathered on the different tissues being scanned.
Even parts of the body that are surrounded by bone can be clearly seen with an MRI scan, making it an ideal device for examining the spinal cord and brain.
MRI scans are helpful for finding tumors in the brain, as well as determining whether the cancer has spread beyond its place of origin. Many different studies on the brain can be done with MRI.
The heart and blood vessels show up clearly on MRI scans. Doctors often order these types of scans to determine whether there are any heart defects, as well as helping them work out whether they are new or long-term problems.