MRI scan : Definition, Working & Uses

What is an MRI scan?

An MRI scan takes a picture of the inside of the body and helps doctors to understand what is going on with the patient. It also helps them to see any blood that may be present. Doctors sometimes use MRI scans to diagnose cancers which they cannot see by any other means.

What kind of images will I see during an MRI?

During an MRI scan the patient lies on a bed and is given a general anesthetic. The scan shows a number of colors, one of these is red. If you watch a red square, then you will see several colored lines, one of these is called a ‘gradient’ because each line is different in color. On the MRI scan you will also see a bright light which the MRI scanner makes come down on the patient.

The MRI scan is usually carried out on the side of the patient. MRI scans help to see parts of the brain and also the bones in the spine.

Why is the doctor making me lie on my side?

Doctors usually lie the patient on their side during an MRI scan. The reason for this is that most parts of the body are round, so the images on the scans will show the body in the round rather than just the face and head.

The MRI scan will show if a person has any deformities which they may not be able to see by looking at them from the side. It will also help to spot if a bone is blocking the blood flow to a part of the body. It also shows whether any disease can be seen on the inside of the body, because the only way to see the inside of the body is by putting someone inside an MRI scanner.

If the results are good then you can then be referred on to a specialist who can decide whether to operate or not.

After MRI scan

After the MRI scan the scan is usually carried out again. The MRI scanner has to be emptied of the magnet and the liquid which they use to make the scans turn pink.

The magnet that is used for the MRI scanner is stronger than the magnets used in hospitals. It is therefore not advised for people to put magnets near them when they are doing these MRI scans. MRI scanners have been known to damage other objects when they are struck by the strong magnet and the liquid inside the MRI scanner.

The MRI scan will take no longer than 15 minutes.

Uses of MRI scan technology

Uses of MRI scan technology continue to evolve as technology improves and techniques expand.

Data can be produced with increasingly higher spatial and temporal resolutions and in particular with the resolution of small groups of tissues or functional units.

MRI vs X-ray

Although X-rays produce only fine-scale and noisy pictures, they have several advantages over MRI.

X-rays provide higher contrast to show anatomy, and are less invasive, so they can be used on non-psychiatric patients.

X-rays can be directed at just one anatomical site without inducing changes in tissue properties, whereas MRI must image the entire body for every functional unit.

When z-scanned with MRI, in the “basic” scanner a thin magnetically transparent strip is laid flat on the surface of a slice of tissue with the transducer beam only extending to the edge of the strip.

This approach has the advantage of allowing the patient to lie on the scanner table or stand while the scanner scan is performed.

Since almost every point along the scanned object will generate some signals, many thin sections can be taken per scan to increase the depth of resolution.

The uses of MRI scans are as follows:

MRI scans are widely used in medicine and are required for most medical diagnosis, including trauma, and for diagnosing medical conditions in many other fields, such as radiology.

Techniques vary widely

Diagnostic MRI machines have a fully enclosed disk containing one or more magnets, which is suspended in a fixed frame with the coil between them.

The MRI machine produces an image in the “bore” of the coil through the use of magnets placed on the frame in a pattern around the coil (i.e.

magnetic field is oriented perpendicular to the axis of the linear frame) or across the body in a magnetic field whose direction changes as the magnetic field passes through an organ.

Generally, the MRI machine scans in two different ways:

In a conventional MRI scanner, the patient (patient being the term given to the object under study) or an object under study (such as an organ) is moved through a magnetic field to produce an image of the object.

In contrast, in a magnetization-prepared fluid imaging scanner, the scanning frame is fixed to a frame, and the patient or object is immersed in an oil-in-water solution called magnetization-prepared fluid (MPF).

The MRI fluid is a solution of ferromagnetic substances, such as magnesium dichromate (a magnetic monopole) and sodium bisulfate, which are immersed in a nonmagnetic, anionic solution of metal salts (sodium chloride and potassium chloride).

The magnetization of the MPF is then increased by means of electrical currents and the subject is moved through the magnetization-prepared fluid to generate images of the MPF in cross-sectional geometry (typically z-direction) of 3-dimensional volume.

The MRI fluid is superposed on a normal water stream

When the patient or object moves through the magnetic field, the magnetization of the MPF is continuously changed by means of electrical currents (generally sinusoidal).

Because MPF’s magnetic field is varying over time, the MRI scanner generates two images of the magnetization change of the MPF.

The two images are typically gathered at the same time to produce a single image called an image progression.

An MRI cross-sectional image is obtained when two compartments of the MPF are viewed.

Depending on the rotation of the MPF, the cross-sectional image of the MPF will form different patterns.

The patterns are dependent on the relative phase of the direction of the magnetic field.

Therefore, these patterns provide us information about the mechanism that the magnetization changes (an MPF’s magnetic field can be divided into x and y components: the angular positions of the direction and the magnitude of the field).

Thus, MR images can be classified as:

  1.  A static cross sectional image
  2. A dynamic cross sectional image
A static cross sectional image

The static images are obtained when the MRI scanner is moving at a constant speed, such as a “normal” level rotation.

In this case, the images show the MEPFs of the same state, hence they may be seen as a rectangular object.

A dynamic cross sectional image

The dynamic images are obtained when the MRI scanner is moving at a random speed, such as a “hyper” level rotation.

In this case, the images show the MEPFs of different states of magnetization, since the MR images show the MPFs of the same states.

Therefore, a dynamic image will show a cross section of the magnetization as well as the MEPFs.


  • A static image is obtained when the MRI scanner is moving at a constant speed, whereas a dynamic image is obtained when the MRI scanner is moving at a random speed.
  • A static image is obtained when the MRI scanner is moving at a constant speed, whereas a dynamic image is obtained when the MRI scanner is moving at a random speed.
  • A static image is obtained when the MRI scanner is moving at a constant speed, whereas a dynamic image is obtained when the MRI scanner is moving at a random speed.

What to do before going for MRI scan

Before undertaking MRI scan, you must first make an appointment with your doctor. However, if your doctor is unable to make the necessary appointment for you, you should get yourself seen in the hospital before the procedure. You can use radiotherapy line or any of the NHS online portals to book your appointment at the radiology department or in a center.

Are there any side effects after MRI scan?

It depends on the type of scan. Most common side effects include headache and nausea, but some people have more severe reactions. If you are claustrophobic or prone to panic attacks, you may want to avoid this type of scan.

On the other hand, if you’re a child who has severe head trauma, get to the hospital immediately. You may have internal bleeding, concussion, or head injury that can cause damage to your brain and nervous system. Sometimes the injury can lead to brain death, severe disability, or even death.

Is it Safe for a Person who is Above 75 Years?

The best answer to this question is yes. You need to know this is because the machine is designed to run for 2 hours non-stop. If a person is above 75 years of age then you will need to get him/her moved to the second or third round of the scan.

If you ask any person in their 60s to do the same, then you will surely know what kind of discomfort and problems they will be facing during the scan. The whole process of getting your MRI scan done will be a very long process and will make you feel pain.

Preparing Your Child for an MRI Scan

A normal MRI scan is a very simple procedure. It takes about 10 minutes and just involves lying in a tube for about 45 minutes. You’ll probably get some headphones and be able to watch a movie or maybe read. You’ll probably also get a chance to sleep, but you won’t need to get under any medication for that.

Keep Your Child Awake

There will be no choice about whether your child is awake or asleep during an MRI. When you go to the doctor to discuss an MRI scan, you will be given a sheet that lists the different tests that your child will have to undergo. There is nothing you can do to make sure that your child is awake during the scan, so be prepared for it.

Make Sure That Your Child Gets Proper Sleep

The last thing you want is for your child to be wide awake for 45 minutes. Because of that, it’s very important that your child is allowed enough sleep in the hours leading up to the MRI scan.

Make Sure That Your Child Wears Heels

Because an MRI machine works in an underground tunnel, your child will have to go down to the entrance in high heels. The only solution is to make sure that the child goes down in flats. Your child should wear pumps or ballet flats or even flip-flops, since that’s what they wear to school anyway.

Put An Acupressure Necklace On

An acupressure necklace is especially helpful if your child is having claustrophobia. The necklace will help to calm and relax the child by vibrating against the back of their neck. This is a great solution if your child wants to leave the room during the test, but it’s important to make sure that this doesn’t get too annoying and make the child too stressed out. If you do decide to wear an acupressure necklace, you can use it the night before your child has the scan.

Turn On Your Phone’s Bluetooth

Have your phone on and set to the Bluetooth setting for your child to wear during the MRI scan. This is a great way to keep your child busy. It also allows them to play music through the headphones.

Buy a Talking-To Toy

The child will be told not to talk or to yell through the test, but they might not listen. Buy a talking toy that makes noise to keep them occupied.

Get A Radio

Some MRI machines can have a radio in them to listen to the traffic on the way to the hospital. This will be a distraction to the child who is in the MRI machine.

Have Sensitivity Cards

Gently go through the MRI procedure with the child to show them what to expect. You can show them the MRI machines and ask if they know what an MRI is.

Get a CD or Tape of Child Music

Be sure that you bring a CD or tape of music that is child-appropriate. This can be something the child can listen to and try and enjoy, and hopefully remain happy.


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