Do you know how an MRI works?

By Kim Smiley

About 30 million magnetic resonance imaging (MRI) scans are performed in the United States each year. They are most frequently used to create images of the brain and spinal cord, but can also help diagnose aneurysms, eye and inner ear disorders, strokes, tumors and other medical issues. MRIs are painless and do not expose a patient to potentially harmful radiation, making them one of the safest medical procedures available.

MRIs are fairly common and most people have heard of them, but do you have any idea how they work?  A Process Map is used to document how a work process is performed, which can be useful when explaining how a process works to somebody who is unfamiliar with it.  To view a high level Process Map of how an MRI is used to create an image, click on “Download PDF”.

The high level Process Map is very basic and would not be useful to somebody trying to learn how to perform an MRI, but it might be helpful in explaining to a patient what to expect during the procedure and how an MRI image is produced.  A more detailed Process Map that included information on each step that needs to be done to perform an MRI could be built for use as a training aid or as a way to document best work practices, but sometimes a basic high level Process Map can also be helpful.

So how does an MRI create detailed images of the inside of a human body? An MRI uses a strong magnet to create a large, steady magnetic field around the patient’s body.  Many atoms, such as hydrogen atoms, have strong magnetic moments that cause them to align in the same direction when exposed to a magnetic field.  Once atoms in the patient’s body are aligned along the field lines of the large magnet, the MRI machine produces a pulse of radio frequency current.  During the pulse of energy (which is extremely brief), atoms in the patient’s body absorb this energy and rotate to align with the radio frequency current.  Once the pulse is over, the atoms will rotate back to their original position, emitting energy.  Atoms in different types of body tissue return to their original positions at different rates and release different energy signals. The body is pulsed many times by different frequencies at different locations to target the specific type of issue being looked at by the MRI. All of the energy emitted by the atoms during these pulses is collected by antennas and a computer uses a mathematical formula to convert the data into images.

Obviously this is a very high level explanation that leaves out a lot of detail, but the basic idea is that an MRI uses changing magnetic fields and the body’s natural magnetic properties to produce detailed images of the human body.  The patient’s role during an MRI is simple (if maybe a little claustrophobic), but the process by which the MRI image is produced is fairly complicated to understand.  Having a simple, visible explanation of what is going on may help make a patient feel more comfortable with their experience.

Can you think of a time when it would be useful to explain the big picture of a work process to somebody, whether a manager or a customer? Creating a simple high Level Process Map to help explain a process to people that aren’t directly involved in the work is something that can be useful across many industries.