A patient in the U.K. who recently posted a video on TikTok recounting her unpleasant experience with hair extensions during an MRI scan has highlighted an issue that is becoming increasingly common.
Savannah McAllister said in her video that she was not asked before the MRI exam if she had extensions. She said that it was only when she told the technician that she felt her hair pulling that she was asked if she had extensions. She said that the technician then advised her to "put her hair up to minimize the pulling," and the MRI continued without incident.
In the nearly 6,000 comments under McAllister’s video, the reaction was mixed, with some people saying that the presence of metal in extensions was common knowledge, and others saying that they did not know of this either. Among those weighing in were those saying they were in the radiology field or were stylists, offering varying opinions or judgment on McAllister’s story.
A search on TikTok unearths an extensive selection of videos of people relating experiences in undergoing MRI scans while having hair extensions that attach with metal beads or clips, or having metal components.
“If scanning body parts away from the head or neck, it’s unlikely that the clips for hair extensions will cause image quality problems,” MRI safety expert Tobias Gilk told AuntMinnieEurope.com in an email. “But if the clips are ferromagnetic the patient may feel uncomfortable ‘pulling’ no matter which body part is being scanned.”
Gilk said that he was not aware of any cases involving patient harm due to hair extensions or their clips, and any danger they might present would be minimal.
Love Engstrom Nordin, PhD, an MR physicist at Karolinska University Hospital in Stockholm, and Titti Owman, a medical research assistant in diagnostic radiology at Lund Medical University Hospital in Sweden, think asking about hair extensions in the mandatory patient questionnaire for MRI exams is not a good idea because such a questionnaire "should only include questions that can cause negative health effects or potentially pose a risk to patients and/or staff."
According to Nordin and Owman, "To try to prevent and avoid this type of MR-incidents in the future, one could include this information in the patient information that is attached to the MRI appointment letter, by phrasing it something like: Before the MRI exam, you should avoid makeup, hairspray, and dry shampoo. Patients should also contact the MRI facility if they have hair extensions."
In addition to the fact that these hair extensions can detach, they can also cause artifacts during brain scans, they continued. "If the extension comes loose, it (or small parts of it) could even be drawn into the magnet itself, causing significant problems there. Metal shavings or metal powder in the magnet can damage the magnetic field itself."
Other hair issues/products that can also cause problematic imaging artifacts during head exams are certain hairsprays with color, and even dry shampoo can create artifacts on MR images, they added.
Hospital protocols
Many MRI facilities include hair extensions on their lists of items to screen for, but not all clinics do, and they may not communicate the potential effects or risks -- however minor -- to patients, according to an article posted on 10 March by the Daily Mail, a U.K. national newspaper.
Some hair stylists offer guidance on MRI compatibility, as only some types of extensions are at issue (clip-in or micro-link extensions, for example, which have metal components as attachments.) Even so, stylists may not know the composition of all components in the extensions used.
Moreover, the process of getting the extensions, which are intended to be in the hair for weeks or months, is expensive and time-consuming; their removal is also not a quick or simple process and is generally done by the stylist. If necessary, they may be removed by the individual, but this too may be a tedious process: Several MRI-related TikTok videos show people employing needle-nosed pliers to unfasten their extensions before a procedure.
A U.K. National Health Service (NHS) risk assessment guide from 2017 states that “to-date, no adverse incident has been published of a case where any patient with hair extensions with metallic attachments has come to harm as a result of entering or being scanned in the MRI environment,” and concludes that “there is no evidence to suggest scanning a patient with hair extensions with metallic attachments presents a significant risk of injury to the patient,” although it cautions that the metal, whether ferrous or not, entails some risk of burns. But that risk is considered minor, Gilk noted.
“The risk of significant heating/burning is likely vanishingly small," he said. "The U.S. FDA came out with a report several years ago in which they state that dangerous RF heating of implanted electrically conductive items that were 2 cm or smaller in electrically conductive length was a functional impossibility at field strengths of 3 tesla or less.
“The FDA document does include some caveats (small objects not in close proximity to another electrically conductive object), but it is also written for objects within the patient’s body. Metal clips for hair extensions may very well be near other metal clips, but they’re in air, not in human tissue, making the wavelengths of the RF considerably longer (increasing the mismatch between the size of the conductor and the RF wavelength), making resonant circuit heating of these tiny clips even less likely.”
However, MRIs may also need to be performed in cases in which the patient may be under sedation or anesthetized; in such instances, the patient may be incapable of registering or reporting any pain or burning.
In an article published in Radiology Case Reports in 2022, Dr. Ravish Kapoor and colleagues from the University of Texas MD Anderson Cancer Center in Houston described a case in which a woman scheduled for MRI of the cervical spine under anesthesia presented with extensions attached with metallic microbeads. The microbeads were deemed under x-ray to pose a significant enough safety risk due to their quantity and configuration, the location of imaging, and the use of anesthesia, to necessitate rescheduling the MRI until after the extensions were removed. Considering the risks presented in this particular case, the authors recommend including extensions in the screening process.
Although the risks of hair extensions with metal components are minor, extensions themselves have become increasingly common, and thus more patients undergoing MRI will have them. Screening for them and informing patients of their possible effects during imaging -- e.g., hair-pulling, as McAllister experienced -- may ensure better outcomes.
