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Asked by anon-292077 to Rosie on 15 Apr 2021.
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Rosie Goodburn answered on 15 Apr 2021: last edited 15 Apr 2021 10:33 am
Hi Jamie! Thanks for your question 🙂
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MRI scanners have a powerful magnet that creates a strong magnetic field.
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MRI works by detecting how hydrogen atoms in the patient’s body respond to this electromagnetic energy. Once the patient is in the scanner, the hydrogen atoms line up with the scanner’s magnetic field, like how a magnet can pull the needle of a compass.
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Pulses of radio waves are then applied, which disrupt this alignment. As each pulse ends, the hydrogen atoms return to their previous states emitting a tiny radio signal as they go.
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Would you like me to tell you about how we know where each hydrogen atom signal comes from? Like how we can tell if a signal is from the head or the feet?
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Comments
Ross commented on :
Hi Jamie, I had no idea how MRI’s work so I had a look, but I can’t explain better than Rosie already has!
I did find a good website with some short videos if you’d like to know more: https://www.nibib.nih.gov/science-education/science-topics/magnetic-resonance-imaging-mri#:~:text=How%20does%20MRI%20work%3F,-MRI%20of%20a&text=MRIs%20employ%20powerful%20magnets%20which,pull%20of%20the%20magnetic%20field
Ed commented on :
Hi, I’ve been studying MRI Scanners for 9-years. They are effectively really, really expensive cameras (like millions of pounds). They use the fact that water, or more specifically hydrogen in water has a fantastic quantum mechanical property called spin that it can be ‘up’ or ‘down.’ Using magnets and radio-wave we can see there quantum spins and get lovely pictures of the water inside the body. The maths for how they work is very complicated, so I won’t post it here, but trust me its AWSOME.