The Physics Behind MRI: Understanding Magnetic Fields and Radio Waves

Some people will go through their entire lives without needing to subject themselves to an MRI. Others will have many of them. MRIs can be utilized for many things, and their value has long been understood by the medical community.

You can get an MRI, St. George residents, if you have sustained an injury or you have various medical conditions that make imaging necessary. Before you do, though, you might want to learn a little more about MRIs, how they work, and what exactly they are capable of. Let’s talk about them in greater detail right now.

What is the Purpose of an MRI?

Before we delve into the science behind MRI machines that are used in hospitals and other medical facilities, let’s make sure you know what happens when you use one of them. MRI is shorthand for magnetic resonance imaging. If you need an MRI, you are placed on a moving table that slides into a long tube.

You might be required to be slid all the way into the tube if a part of your body like your head or shoulder is being examined. However, if the medical professionals operating the MRI want to look at something lower down on your body, like a knee or ankle, for instance, they will only require that you be slid partway into the tube.

This is definitely better for individuals who are claustrophobic. While being slid all the way into the tube is not an issue for some people, others find it terrifying. They are told to hold still, or the images being taken will not be usable, and some find this to be exceedingly difficult.

Those who have a hard time with it are often told to practice deep breathing. Others employ meditation techniques, while some ingest calming drugs before they must go through the MRI process. It usually takes anywhere from 30-45 minutes.

Now, let’s get into the technology that goes into this useful piece of diagnostic equipment.

The Basics

We’ll start with a general overview of the science involved. An MRI uses strong magnetic fields, as well as radio waves. The intention of utilizing them in this way is to get a highly detailed series of images of the human body’s interior that would not otherwise be possible to create.

The body is full of hydrogen atoms, and, as you lie in the tube, these are aligned with the magnetic field that is being created. Radio waves are then used for the purpose of disrupting this alignment.

This concept sounds a bit intimidating, but it’s quite harmless. The atoms return quickly to their original state. When they do, they emit signals that can be detected. It is these signals that are used to create the images of the body’s interior that the medical professionals running the MRI machine can then study and analyze.

Further Detail on the MRI Process

Those are the basics, but let’s go a little deeper. The powerful, constant magnetic field that is created by the MRI aligns with the body’s hydrogen atoms, which are also known as protons. You may have learned about them in your high school science classes.

The protons are located in the body’s water molecules. They behave like tiny magnets. They align with the magnetic field in the way we described a moment ago.

Radio waves that are at a very precise frequency then pummel the body, though you won’t ever feel them. It is these RF pulses that go to work disrupting the alignment of the person’s protons who is being subjected to the MRI.

What Happens Next?

The signal emission is the next step. The RF pulses are turned off by whoever is controlling the MRI. They will have received special training in this. The protons return to their original alignment almost instantly. They release energy that takes the form of radio waves.

The MRI machine next detects the radio waves that are being emitted. A powerful computer is then used to create images from the radio waves.

If you were to look at some of these images, they probably would not make a lot of sense to you if you didn’t have medical training. If your doctor goes over the imaging with you afterwards, though, they should be able to explain what it is you’re looking at.

The emitted signals interact with the body of the individual undertaking the MRI at differing strengths. This is also somewhat dependent on the tissue type that is being analyzed.

These signals will create cross-sectional images of body parts. Some of these are more useful when trying to see particular injury types, and others less so.

MRIs Have a Valuable Place Among Modern Medical Tools

It’s hard to overemphasize how important it can be for someone to get an MRI. The technology may be a little mystifying to the average person who lies on a table and is fed slowly into the tube. However, if they have damage to a body part like the brain, shoulder, knee, ankle, etc., this is a fantastic way to get highly detailed images of it that can be used to determine exactly what is wrong.

If you see a football player take a nasty hit on the field and stumble when getting up, indicating a possible concussion, it is more than likely that they’ll have a date with an MRI in their immediate future. While the science is not going to matter overly much to such an individual, were it not in place, the doctors could not get the pictures of their body’s interior that clearly show what damage, if any, just occured.

MRIs might seem a little scary to you if you don’t like the idea of being fed into a narrow tube, but know that the medical technicians who operate these machines are often very kind and can help to talk you through it. You will emerge unscathed, and now you know about the fascinating technology that is being used on you.