A magnetic resonance imaging (MRI) scan is a common procedure around the world.
MRI uses a strong magnetic field and radio waves to create detailed images of the organs and tissues within the body.
Since its invention, doctors and researchers have continued to refine MRI techniques to assist in medical procedures and research. The development of MRI revolutionized medicine.
This article looks specifically at MRI scans, how they work, and how doctors use them.
Fast facts on MRI scanning:
- MRI scanning is a painless and non-invasive treatment.
- The Indomitable was named after Raymond Damadian, who invented the first MRI full-body scanner.
- A typical MRI scanner might cost anywhere from $150,000 to several million dollars.
- With 48 MRI scanners per 100,000 people, Japan has the most MRI scanners per capita.
What is an MRI scan?
An MRI scan uses a large magnet, radio waves, and a computer to create a detailed, cross-sectional image of internal organs and structures.
The scanner itself typically resembles a large tube with a table in the middle, allowing the patient to slide in.
The development of the MRI scan represents a huge milestone for the medical world.
Doctors, scientists, and researchers are now able to examine the inside of the human body in high detail using a non-invasive tool.
The following are examples in which an MRI scanner would be used:
- anomalies of the brain and spinal cord
- Tumors, cysts, and other anomalies in various parts of the body.
- Breast cancer screening is for women who face a high risk of breast cancer.
- injuries or abnormalities of the joints, such as the back and knee.
- Certain types of heart problems
- diseases of the liver and other abdominal organs.
- The evaluation of pelvic pain in women with causes including fibroids and endometriosis
- Suspected uterine anomalies in women undergoing evaluation for infertility
This list is by no means exhaustive. The use of MRI technology is always expanding in scope and use.
There is very little preparation required before an MRI scan.
Doctors may ask the patient to change into a gown when they arrive at the hospital. Because magnets are employed, no metal objects should be present in the scanner. Any metal jewelry or accessories that could interfere with the machine will be asked to be removed by the doctor.
If a person has any metal inside their body, such as bullets, shrapnel, or other metallic foreign bodies, they will most likely be unable to get an MRI. Medical equipment such as cochlear implants, aneurysm clips, and pacemakers are examples of this.
People who are afraid of being in enclosed spaces should tell their doctor. Prior to the MRI, individuals may be given medication to make the procedure more comfortable.
In order to boost the visibility of a specific tissue that is relevant to the scan, patients may be given an injection of intravenous (IV) contrast liquid.
The radiologist, who is a specialist who specializes in medical pictures, will next walk the patient through the MRI scanning procedure and answer any questions they may have.
When the patient enters the scanning room, the doctor will assist them in lying down on the scanner table. Staff will provide blankets or pillows to make them as comfortable as possible.
Earplugs or headphones will be provided to block out the loud noises of the scanner. The latter is popular with children, as they can listen to music to calm any anxiety during the procedure.
During an MRI scan
Once in the scanner, the MRI technician will communicate with the patient via the intercom to make sure that they are comfortable. They will not start the scan until the patient is ready.
During the scan, it is vital to stay still. Any movement will disrupt the images, much like a camera trying to take a picture of a moving object. Loud clanging noises will come from the scanner. This is perfectly normal. Depending on the images, at times it may be necessary for the person to hold their breath.
If the patient feels uncomfortable during the procedure, they can speak to the MRI technician via the intercom and request that the scan be stopped.
After an MRI scan
After the scan, the radiologist will examine the images to check whether any more are required. If the radiologist is satisfied, the patient can go home.
The radiologist will prepare a report for the requesting doctor. Patients are usually asked to make an appointment with their doctor to discuss the results.
It is extremely rare that a patient will experience side effects from an MRI scan.
However, the contrast dye can cause nausea, headaches, and pain or burn at the point of injection in some people. Allergy to the contrast material is also seldom seen but possible and can cause hives or itchy eyes. Notify the technician if any adverse reactions occur.
People who experience claustrophobia or feel uncomfortable in enclosed spaces sometimes express difficulties with undergoing an MRI scan.
An MRI scanner contains two powerful magnets. These are the most important parts of the equipment.
Water molecules, which are made up of hydrogen and oxygen atoms, make up the majority of the human body. Each atom has a tiny particle called a proton at its center, which acts as a magnet and is sensitive to magnetic fields.
The water molecules in the body are normally randomly oriented, but the first magnet in an MRI scanner induces them to align in one direction, either north or south.
The second magnetic field is then cycled on and off in a series of fast pulses, causing each hydrogen atom to shift alignment when switched on and swiftly return to its relaxed condition when switched off.
The magnetic field is created by passing electricity through gradient coils, which also causes the coils to vibrate, resulting in a knocking sound inside the scanner.
Although the patient is unaware of the changes, the scanner may identify them and provide a thorough cross-sectional image for the radiologist using a computer and a scanner.
Functional magnetic resonance imaging (fMRI)
Functional magnetic resonance imaging, or functional MRI (fMRI), uses MRI technology to measure cognitive activity by monitoring blood flow to certain areas of the brain.
Blood flow increases in areas where neurons are active. This gives an insight into the activity of neurons in the brain. This method has transformed brain mapping by allowing researchers to examine the brain and spinal cord without intrusive surgeries or medication injections.
Researchers can use functional MRI to learn about the function of a healthy, diseased, or wounded brain.
In clinical practice, fMRI is also used. Standard MRI images are useful for detecting tissue structural problems. An fMRI scan, on the other hand, can aid in the detection of activity irregularities.
In other words, fMRI examines how tissues function rather than how they seem.
As a result, surgeons utilize fMRI to estimate the risks of brain surgery by identifying the brain regions involved in important processes, including speech, movement, perception, and planning. Tumors, strokes, and head and neck cancers can all be detected with functional MRI.
How long will an MRI scan take?
MRI scans vary from 20 to 60 minutes, depending on what part of the body is being analyzed and how many images are required.
If, after the first MRI scan, the images are not clear enough for the radiologist, they may ask the patient to undergo a second scan straight away.
I have braces or filings, should I still undergo the scan?
Although braces and fillings are unaffected by the scan, they may distort certain images. The doctor and technician will discuss this beforehand. The MRI scan may take longer if additional images are required.
Can I move while I am in the MRI tunnel?
It is important to stay as still as possible while in the MRI scanner. Any movement will distort the scanner and, therefore, the images produced will be blurry. In particularly long MRI scans, the MRI technician may allow a short break halfway through the procedure.
I am claustrophobic, what can I do?
The doctor and radiologist will be able to talk the patient through the whole procedure and address any anxieties. Open MRI scanners are available in some locations for certain body parts to help patients who have claustrophobia.
A person can take medication prior to the test to ease anxiety.
Do I need an injection of contrast before my MRI scan?
A contrast dye can improve diagnostic accuracy by highlighting certain tissues.
Some patients may need to have a contrast agent injected before the scan.
Can I have an MRI scan if I am pregnant?
Unfortunately, there is no simple answer. Let the doctor know about the pregnancy before the scan. There have been relatively few studies on the effect of MRI scans on pregnancy. However, guidelines published in 2016 have shed more light on the issue.
Typically, doctors do not recommend contrast material for women who are pregnant.
MRI scans should be restricted during the first trimester unless the information is considered essential. MRI scans during the second and third trimesters are safe at 3.0 tesla (T) or less. A tesla is a measurement of magnetic strength.
The guidelines also state that exposure to MRI during the first trimester is not linked to long-term consequences and should not raise clinical concerns.