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.
Why Are MRIs So Loud Or Noisy?
MRIs (Magnetic Resonance Imaging) can be pretty noisy during scanning. There are a few reasons why MRIs produce loud or noisy sounds:
Magnet vibrations: MRI machines use powerful magnets to create detailed images of the body’s internal structures. These magnets generate intense magnetic fields, which can cause the metal components within the machine to vibrate. These vibrations can produce loud banging or knocking sounds.
Gradient coils: MRI machines also use gradient coils, which are smaller magnets that help create detailed images by manipulating the magnetic field. These gradient coils can rapidly switch on and off, causing rapid changes in the magnetic field, which results in repetitive tapping or buzzing noises.
Radiofrequency coils: Radiofrequency coils transmit and receive radio waves during the MRI scan. These coils emit signals to stimulate the body’s tissues and receive signals to create images. Radiofrequency pulses can produce clicking or buzzing sounds.
Resonance effects: Some noises produced during an MRI scan are due to resonance effects. The rapid switching of magnetic fields and gradients can cause the metal components of the machine to vibrate at their natural resonant frequencies, resulting in louder noises.
The loudness of MRI noises can vary depending on the type of scan and the specific MRI machine. Technological advancements have been made to reduce the noise level, such as using quieter gradient coils and implementing sound insulation measures. Some MRI facilities also provide earplugs or headphones to help patients tolerate the noise better during the scan.
In an interview, Clare Mackay said, An MRI scan is a way of using a giant 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 photos 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 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 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 feel nervous about your MRI, try listening to the noise before your appointment.