How an MRI Scan is Used to Learn More About the Brain

MRI brain

Have you ever figured in an accident where you thumped your head hard on the floor, or on any hard surface? I hope you haven’t yet, because I’m sure you’re aware of the severity of head injuries. But, if ever you figured in an accident, do you remember getting an MRI scan? To study the brain scientists and doctors use a machine that’s called an MRI, or Magnetic Resonance Imaging, scanner. The scanner takes pictures of the brain in a safe way, and allows doctors and scientists to learn about the brain’s structure and functions. Read on to learn more about MRI brain scans.

An MRI Uses a Strong Magnet to Take Pictures of the Brain

An MRI brain scanner uses a strong magnet to take pictures of the brain and then measure its activity in a safe, harmless and reliable manner. The picture allows for easy and targeted identification of the mouth, tongue and nose too.

The imaging also allows scientists and doctors to identify the different parts of the brain like the brain stem, cerebral cortex, cerebellum and a lot more. Since the brain is three-dimensional, a single photo would not be sufficient to capture all of its sides or parts. Instead, the MRI brain scan utilizes a strong magnet to take a series of pictures which virtually cut through the brain in multiple slices, which can then be combined into a 3D image.

How Much Detail Can MRI Data Have

So, how much data or information can an MRI brain scan gather or generate? Well, think about a picture taken by a conventional camera. If you closer at the photo, you will see small squares that are called pixels.

A picture with more pixels looks clearer and crisper, and provides more details to the one looking at the photo. However, an MRI scanner cannot use 2D pixels to create a picture of the 3D brain. Instead, it uses a 3D version of a pixel called a “voxel”. A voxel is just like a tiny, minute cube with edges of 1 to 3 mm. The MRI brain scanner takes images of each brain slice with many voxels per image, which makes for a final, high-resolution 3D image of the brain.

Keep in mind that the clarity or sharpness of an image may depend on whether you’re taking a photo of something that’s moving or something that’s still. For instance, if you’re taking a photo of a running cat or dog, it will definitely be blurry no matter how many pixels the photo has.

But, if the cat or dog stays still and you take a photo with enough pixels, then you can get a clearer of the animal. Although the MRI brain scan can take high-quality photos, it’s important for the participant or patient to stay as still as possible while the MRI creates images of the brain.

Through the MRI brain scan scientists and doctors can learn a great deal about the size and shape of the different parts of the brain from the high-resolution images generated. They can also study how the shapes and sizes of the different brain parts change as an individual gets older. Physicians can also use MRI scanners in hospitals and clinics to get clear and more accurate images of a patient’s brain, or some other body part.

What Happens When a Part of the Brain Becomes Active?

According to scientists and doctors, different parts of the human brain become more active when the individual does different things.  For instance, the area in the back of the brain becomes more active when the person sees things that are very important or meaningful to them.

The scientists found this out by using an MRI brain scanner to compare brain activity, through showing to a volunteer picture of his friend versus a blank screen. The areas in the occipital lobe showed greater activity when the volunteer saw a picture of a friend, obviously because the photo is more meaningful than a blank screen.

When parts of the human brain become active, nerve cells called neurons communicate with each other. Neurons in active parts of the brain require more oxygen to communicate. But, how do the active parts of the brain get their fresh supply of oxygen?  Well, the blood carries oxygen through the blood vessels, and into the brain.

As blood contains a protein called hemoglobin, when hemoglobin holds onto oxygen it is called oxygenated hemoglobin, and when hemoglobin is not holding oxygen it is called deoxygenated hemoglobin. And, when an area of the brain becomes active the oxygenated hemoglobin begins to dislodge or displace the deoxygenated hemoglobin.

And, when a part of the brain becomes active, there is a “hemodynamic response”, wherein the expansion of blood vessels allows more oxygen to flow into the more active areas of the brain.

A hemodynamic response happens when the blood vessels in the brain’s active areas become wider. This widening allows for entry of more oxygenated hemoglobin into the active parts of the brain to supply it with precious oxygen.

The MRI brain scan also uses the strong magnet to measure a signal called BOLD, or Blood Oxygenation Level Dependent signal. The BOLD signal is recorded by the MRI scanner. And, the more active the region of the bran, the greater the oxygen level as well as the BOLD signal.

The Benefits, and Potential Risks, or MRI Scans

So, what are the benefits, and potential risks, of an MRI brain scan to patients and doctors? Well, for starters an MRI scan provides better soft tissue contract than CT scans, and it can also differentiate much better between fat, water, muscle and soft tissue than CT scans. The high-resolution images provide information to physicians, which can be very useful in diagnosing a wide array of diseases and conditions.

Now, for the potential risks of MRI brain scans. While MRI images are made without using any ionizing radiation, which means that patients are not exposed to harmful radiation, the MRI environment involves a strong static, magnetic field which also carries certain safety concerns.

The strong and static magnetic field will attract magnetic objects like small keys, forks and spoons, and even mobile phones or even oxygen tanks and floor buffers, and these may cause damage to the scanner, or cause an injury to the patient or medical professional if the objects become projectiles.

The radiofrequency energy that’s also used during the MRI brain scan could also lead to heating of the body. The use of GBCA’s, or gadolinium-based contract agents, also carries some risks for allergic reactions to the patient undergoing the scan.

But then again, the benefits certainly outweigh the risks. Overall, an MRI brain scan offers more advantages to patients, doctors and researchers especially in terms of understanding the brain and other body parts, as well as in diagnosing various diseases and medical conditions.