Will an MRI be loud?

Yes, and louder than most people expect. The National Institute of Biomedical Imaging and Bioengineering puts the sound intensity as high as 120 decibels in certain scanners. That is why ear protection is part of the procedure rather than an optional comfort.

The National Cancer Institute describes what you will hear: loud thumping noises and rhythmic beats. Others describe clicking and beeping. None of it means anything is wrong with you or with the machine.

Where the noise comes from

An MRI uses a powerful magnet and radio waves, not radiation, to take pictures of your body in slices. Those slices are combined into detailed images that can show where tumors may be.

To build each slice, the scanner switches magnetic fields on and off very rapidly. The FDA describes it directly: magnetic fields that change with time create loud knocking noises. The coils that produce those fields flex and snap against their mountings thousands of times a minute, and that is the banging you hear. Faster imaging sequences make different rhythms, which is why the noise pattern changes partway through the scan.

Protecting your hearing is not optional

The FDA warns that these noises may harm hearing if adequate ear protection is not used. Hearing loss and tinnitus, meaning ringing in the ears, are among the adverse events reported to the agency for MRI.

So take the earplugs or headphones you are offered, and make sure they fit before the table moves. If you are not offered anything, ask. Some centers can play music through MRI-safe headphones, which both protects and distracts.

Speak up during the scan if the noise becomes painful, if you feel a twitching sensation in a muscle, or if any part of your body feels hot. There is an intercom in the room and you can talk to the operator at any time. Rapidly changing magnetic fields can stimulate nerves or muscle, which feels like twitching, and heating and burns are the most commonly reported problem with MRI. None of that should be endured quietly.

How long you will be in there

A scan usually runs about 30 to 60 minutes, and sometimes longer. The operator watches you from another room the whole time.

You need to stay very still, because movement blurs the images and can force a repeat. The table may feel hard or cold, and you can ask for a blanket or a pillow.

If enclosed spaces are the real problem

For many people the noise is bearable and the tube is not. Say so before the appointment rather than on the table.

There are several answers. Medicine can be given to make you sleepy and less anxious. Some centers offer an open MRI, which is open at the sides instead of being a closed tube; it was designed for people who cannot tolerate the tunnel and for people whose size makes a standard scanner impractical. Newer open scanners give good images for many, though not all, types of exam. Other options are a panic button to hold, a television or video to watch, music through headphones, or simply keeping your eyes closed or covered.

One safety point unrelated to noise: tell the staff about any implant, pacemaker, or metal in your body, and about past work with sheet metal, since fragments in the eye may need to be checked for first. The magnet is strong enough to move metal objects, and it extends beyond the machine itself.

Sources

https://www.cancer.gov/about-cancer/diagnosis-staging/diagnosis

https://www.nibib.nih.gov/science-education/science-topics/magnetic-resonance-imaging-mri

https://www.fda.gov/radiation-emitting-products/mri-magnetic-resonance-imaging/benefits-and-risks

https://medlineplus.gov/ency/article/003335.htm