MRI is noisy or loud because its magnetic field is created by running an electrical current through a coiled wire, an electromagnet. When the current is switched on, there’s an outward force along the coil. As the magnet field is so strong, the force on the coil is huge and goes from zero to huge in milliseconds, which causes the coil to expand slightly, which results in that loud click.
As for capturing your image on the MRI, the current is switching on and off rapidly, which creates rapid-fire clicking noises. So that is the noise that you’re hearing. But remember, you’re always free to wear earplugs or ask for noise-canceling headphones.
In an interview, Clare Mackay said, An MRI scan is a way of using a big magnet and some radio waves to obtain beautiful pictures of the inside of the brain. It’s essential for dementia research because it gives us pictures of the brain. That shows whether any cells have been lost and where those cells might have been lost in the brain. Clare Mackay is a professor of imaging neuroscience, leading the magnetic resonance imaging part of the Deep and Frequent Phenotyping study.
So when you go into an MRI scanner and the tube, you’ll have something put over your face that might look a little frightening at first, but there are plenty of gaps in it so you can see outside. This thing is called a head coil, and that’s necessary because that’s the piece of apparatus that picks up the signals that we want to measure that make up a brain scan.
The decibel levels with MRI vary for the specific sequences. The main magnetic field is always on. Three smaller magnets are turning on and off rapidly. That’s how it produces images and powers the magnets on and off. That’s creating the loud banging.
With new technology, specialists offer music that helps tremendously with claustrophobic patients. Other people find it very relaxing and rhythmic. They fall asleep there. The noise is banging, but it’s not terrible. If you’re feeling nervous about your MRI, try listening to the noise before your appointment.