Magnetic resonance imaging (MRI) utilizes a strong magnetic field to create images of your body so that your physician can get an idea of what a region of interest (ROI) looks like. These images can show your doctor what is going on in the desired region of the body. As you prepare to enter an MRI scan, there are a few things that will help increase the safety of your scan that you should keep in mind.
Protecting your hearing
Even though technology improvements have helped with reducing noise levels of MRIs, many MRI scanners can be loud. The magnet creates the magnetic field, which agitates the coils inside the machine. These coils receive the signals that your body creates in response to the pulse sequences that are used during an MRI scan. Pulse sequences manipulate the gradient coil inside of the scanner and alter the magnetic field, resulting in the ability to create the necessary images.1 As the coils are agitated by this magnetic field, they begin to vibrate, causing the signature loud banging. The average sound generated during an MRI scan is roughly 110 decibels of noise, which is the same level as that produced by a rock concert.2
Many MRI scanner manufacturers are investigating and producing quieter scanners.2 This is done by altering how the image is acquired. This technology reduces the noise to that of regular background noise. However, this technology may not be widespread.
If the MRI location does not have the ability to take a quieter scan, it is important that you wear ear plugs or specially designed headphones which contain no metal.3 The technologist should give you ear plugs or MRI headphones as part of their routine. However, if they forget, ask for them yourself. This will help to protect your hearing, as the noise of the scan may affect your hearing for a few days.3
Protecting yourself and your devices
Many people know that jewelry or clothing containing metal can cause issues during an MRI. Items containing metal run the risk of being pulled into the magnet, heating up during the scan or interfering with a device’s function. Jewelry, clothing, tattoos, implants, pacemakers and electronic devices are risk factors in the MRI suite.
Metals containing iron, also known as ferrous magnets, may be an increased risk for being pulled into the magnet. There is a small chance that metal jewelry and clothing containing metal could be pulled toward the magnet. Foreign objects could damage both the scanner itself and you. Implants and pacemakers facing the magnetic pull of the scanner may end up being moved.
Jewelry and other conductive materials, including those inside of pacemakers and implants. could heat up during the scanner and should be left outside of the MR suite. Clothing that contains metal can do the same thing, irritating your skin where the clothing rests. Hospitals often provide scrubs to wear during the scan. If your facility does not, follow the clothing guidelines provided prior to your appointment.
You should also tell your technologist if there is any metal, such as implants or in your body, which could raise the risk of the scan. The magnetic field could alter the function of such devices. Because of this, there are a number of precautions that the technologist can take for patients with MRI conditional devices. Some older pacemakers and implants may not be safe in an MRI scan. Be sure to tell your technologist the model of your device. Many people may not realize that other metal objects, such as smart phones or watches, can have similar issues.
Cell phones typically contain metal, which could be moved by the super-conducting magnet within the scanner.4 If a device containing metal is in the room when a person is being scanned, it could lead to injury. Your technologist will usually provide you with a locker or bag to put your belongings in during the scan, make sure you store all electronic devices to protect both yourself and the staff.
Certain smartphones and smart watches can be affected by the helium used in an MRI scanner. A liquid helium leak caused devices to malfunction during an MRI installation.5 The most interesting thing is that it was only devices made by one manufacturer. The manufacturer later added that helium could alter the function of their devices.5
Protecting your cards
Another precaution to take during an MRI scan relates to your credit, debit or gift cards. The magnetic field in an MRI scanner can damage or de-magnetize the magnetic strip on the back of a card.6 The magnetic strip on the back of a card is created in such a way that it can be read by a scanner at a store or bank. The MRI scanner could alter this magnet, causing further problems using the card. With the advent of cards with chips, the cards also contain metal and could be drawn to the magnet. Along with all your personal belongings, these cards, and your wallet, should be placed in the bag or locker provided by the facility to avoid potential harm.
MRI is an important imaging test, which can provide valuable information that your physician needs to adequately treat any condition that you may have. If your doctor recommends an MRI, there is typically a very good reason they want it done. When you go to have an MRI, it is important to remember to take the precautions that your doctor or the imaging facility staff advises. Ensure you talk to the staff about ear plugs or MRI approved headphones as well as keeping all personal belongings outside of the MRI scanning room to protect yourself and the staff.
1. C. Claiborne Ray. "The Sound and the Fury." NYTimes.com. 16 April 2012. Web. 25 February 2019. <https://www.nytimes.com/2012/04/17/science/why-mri-machines-make-that-loud-noise.html>.
2. Shaunacy Ferro. "GE's Silent MRI Scanner Has Hit The Market." PopSci.com. 12 September 2013. Web. 25 February 2019. <https://www.popsci.com/technology/article/2013-09/silent-mri>.
3. Dave Pearson. “Researchers recommend better hearing protection for MRI patients.” HealthImaging.com. 17 August 2017. Web. 25 February 2019. <https://www.healthimaging.com/topics/diagnostic-imaging/researchers-recommend-better-hearing-protection-mri-patients>.
4. “Don’t get hurt by an MRI.” CNN.com. 26 October 2011. Web. 25 February 2019. <http://thechart.blogs.cnn.com/2011/10/26/dont-get-hurt-by-an-mri/comment-page-1/>.
5. “Keep your iPhone & Apple Watch away from MRI machines; they can start malfunctioning.” EconomicTimes.indianatimes.com. 1 November 2018. Web. 25 February 2019. <https://economictimes.indiatimes.com/magazines/panache/keep-your-iphone-apple-watch-away-from-mri-machines-they-can-start-malfunctioning/articleshow/66461757.cms>.
6. American Heart Association. “Magnetic Resonance Imaging (MRI).” Heart.org. 19 September 2016. Web. 25 February 2019. <http://www.heart.org/HEARTORG/Conditions/HeartAttack/SymptomsDiagnosisofHeartAttack/Magnetic-Resonance-Imaging-MRI_UCM_441632_Article.jsp#.XHQt8OhKi70>.