Applications
One very useful and common application of NMR is the Magnetic Resonance Imaging (MRI).
This section will cover the following:
- What is MRI?
- How does MRI work?
- What are some benefits of using MRI?
- What are some limitations of MRI?
1. What is Magnetic Resonance Imaging (MRI)?
MRI is an application of NMR. It is an a non-invasive and non-destructive diagnostic tool for imaging soft tissues. Soft tissues include the brain, heart, muscles and many other organs. As such, MRI is commonly used to make many medical diagnosis such as the discovery of tumours, bleeding or checking for bone and joint problems.
2. How does MRI work?
Picture of someone who is going to undergo an MRI scan. (Source: howstuffworks.com)
MRI makes use of proton NMR. In clinical MRI, the frequency of the radio waves used is typically between 15 and 80 MHz. The area of the body being studied is placed inside a machine and NMR is carried out. As the body is largely made out of water which contain hydrogen atoms which give off signals in a proton NMR, the concentration of protons can be imaged. Different types of tissue will contain different concentrations of protons. As such, by imaging the concentration of protons, there will be significant contrast to achieve the image of the organs and other tissues.
Picture of an MRI scan of the brain (Source: bannerhealth.com)
An MRI test usually takes 30 to 60 minutes but can take as long as 2 hours.
3. What are the benefits of using MRI?
MRI is non-invasive and non-destructive. There is also no need to be exposed to x-rays which means people who may be very adversely affected by radiation, such as pregnant women and babies can undergo MRI scans.
There are currently no known adverse effects of the MRI.
4. What are some limitations of MRI?
As the MRI makes use of magnets, people with certain types of implants will not be able to use it. Such examples are pacemakers or metal plates, wires, screws or rods which were implanted during surgery after a bone fracture, as well as dental fillings.