What Is an MRI and How Does It Diagnose Diseases?
October 01, 2020
MRI which stands for magnetic resonance imaging is a piece of medical equipment used to take images of bodily structures for a medical diagnosis. MRI machines can be used to take images of the brain, heart, liver, musculoskeletal system, and much more.
MRI machines are non-invasive and radiation-free; they don’t depend on x-rays for medical imaging. MRI machines use a strong magnetic field, radio waves, and a computer to develop images instead.
MRI machines can take image slices from different angles known as planes. The planes used in MRI scans include:
- Axial – separate the top from the bottom.
- Sagittal – separates the left and right side.
- Coronal – separates the front from the back.
Then the specialized computer can stitch the image slices together to create the 2D and 3D images. Paul C. Lauterbur invented MRI technology in the early 1970s. Peter Mansfield later became involved with the project and helped to further advance MRI technology. The initial MRI machines were established in hospitals by the 1980s. In 2003, the pair were honored with a Nobel Prize in Medicine for their outstanding invention which later changed the world.
In the 1980s, there were only 12 MRI machines available around the world. As the years passed, there was a huge surge in the number of MRI machines. Nowadays there are more than 11,900 MRI machines in the US alone.
How does the procedure go?
Patients will need to remove all metal from their bodies for the MRI scan; this means that those with metal implants or pacemakers can’t have an MRI scan because the metal from these devices can interfere with the MRI’s magnetic field.
The patient may require contrast materials for their MRI scan. Contrast materials are quite safe; they can be ingested, injected intravenously, or administered by enema. Contrast materials make it easier to distinguish between different body structures and to determine the presence of abnormalities because it makes the image brighter.
The patient will be asked to lie on the MRI table, and then at some point, the table will be prompted to move into the donut-shaped MRI machine where the MRI scan will happen.
The patient will use a radio frequency coil designed for the specific type of MRI scan they are doing. For example, a brain scan will require a coil for the head; a chest scan will require a coil for the chest, and so on.
The images can’t be made without using the specific coil. Let me explain why! When radio waves are released by the patient’s body; this information is picked up by the specialized coil and sent to the computer to create the MRI images. So it’s a really important part of the process.
Patients must lie still in order to produce the best images possible. Children might be sedated or given anesthesia before the MRI scan for that exact reason. If the child isn’t sedated/ under general anesthesia, the MRI technician can put a movie on to divert the child’s attention and help them to relax.
How long does an MRI take? The MRI machine will take anywhere between 15 minutes and 1 and a ¹/₂ hours. However, this will vary depending on the size of the area and how many images the MRI technician takes.
What are the possible side effects?
The patient may experience side effects after the MRI scan. This may happen because the patient has reacted to the contrast material (if any was used for the MRI scan).
Signs you might be reacting to the contrast material:
- Itchy skin and redness
- Nausea
- Vomiting
- Fatigue
- Hypotension
- Acute bronchospasm
Interestingly, a reaction to the contrast material can happen more than 30 minutes after the MRI scan, so it’s important to remain aware even after the scan. Some patients are more likely to suffer from a reaction than others; these are people with pre-existing health conditions.
Reactions to contrast materials can be recognized, prevented, and even treated. So, the patient should inform their doctor if they notice any side effects after the MRI scan. American Family Physician has explained in more detail how a reaction to contrast materials can be treated and prevented in their research article.
Does an MRI actually work?
Several studies have backed the use of MRI scans to help diagnose diseases affecting various body systems. MRI machines have been tried and tested and are now a part of the healthcare system, you’ll find an MRI machine in each and every hospital you visit because they are extremely useful.
Brain scans allow doctors to observe for visible brain damage like lesions, structural abnormalities, and changes in the quantity of white and grey matter. So, brain scans are very useful and can help to diagnose brain-related diseases including multiple sclerosis, strokes, Alzheimer’s, tumors, etc.
Blood vessels can be imaged with magnetic resonance angiography. This technique can help to determine the state of the blood vessels. Doctors will look out for narrow blood vessels, aneurysms, blockages of the blood vessels, and any other irregularities. These irregularities can be indicative of health conditions like atherosclerosis, aneurysm, and other cardiovascular conditions.
Also, an MRI could be done to observe the patient’s musculoskeletal system for any damage. Again, the MRI scan will be able to show any abnormalities in the bone or muscles like broken bones or fractures, tumors, inflammation, and joint problems associated with arthritis can also be monitored.
MRI advancements
MRI technology has reached new heights since being first developed back in the 1970s. There have been advancements such as open MRI machines, stand-up MRIs, portable MRIs, and even MRI machines paired with AI. Many more MRI advancements are currently in the pipeline, it will be interesting to see what researchers do next.
To read more about MRI scans using AI, click here.
Old MRI?
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Cover Image by Michal Jarmoluk from Pixabay