A woman got blisters on her skin during an MRI exam, just because she was wearing a pair of nice yoga pants?

Wearing yoga pants can help you burn fat as long as you work out hard, but you may not know that they can also burn your skin.

A warning sign is posted on the wall of a medical institution in Pennsylvania, advising people coming in for MRI examinations not to wear a certain brand of yoga pants.

Image source: marketwatch

It seems incomprehensible, but there is a reason for all this...

In 2019, 40-year-old Lisa (not her real name) went to the hospital for an MRI to evaluate a thigh muscle that she had recently been experiencing discomfort in.

She wore a white T-shirt and black sweatpants. Before entering the examination room, Lisa passed through the metal detector screening, and nothing was found. After the examination began, Lisa lay in the MRI machine, and the machine made a buzzing sound and began to scan.

Fifteen minutes later, the examination was over. However, when Lisa stood up, she felt a burning sensation in her legs. The radiologist found red and swollen lines on the outside of her legs. At first, they thought it was just a normal skin reaction. However, over time, these red and swollen lines developed into blisters.

Source: Literature

In 2014, a Canadian woman named Jenn Marr went to the hospital for an MRI and was wearing a pair of yoga pants.

During the procedure, she felt an intense burning sensation. She was not sedated and alerted the radiologist 15 minutes later. The machine was turned off and Marr was not seriously injured. "The burning was so intense that I had to push the emergency button for them to stop the machine and pull me out," she told the Canadian news site.

This is not the first time that someone has been burned by MRI. As early as 2012, a similar incident occurred and was published in the American Journal of Neuroradiology.

An 11-year-old girl undergoing an MRI for scoliosis. There are no buttons, no zippers, no embroidery, and no metal visible to the naked eye.

The patient was screened by a handheld metal detector before entering the MRI room. Intravenous propofol sedation was administered during the examination. To avoid contact between the arm and the side wall of the magnet, the patient's arms were secured to the sides of the body using nylon-Velcro straps.

Here's an explanation: In some developed countries, MRI scans sometimes require sedation. In order to get a clear image, the patient must remain completely still during the scan. Sedation can help patients who can't stay still naturally, especially children.

During the process, the little girl complained of a burning sensation on the right side of her abdomen. A physical examination was performed on the little girl, and it was found that she had a linear erythematous vesicular rash on the right side of her abdomen and the wrist on the same side that was in contact with her underwear. The dermatology consultation diagnosed her with second-degree burns.

The patient developed a linear erythematous vesicular rash on the right abdomen within a few minutes after the MRI examination. Source: Literature

Further investigation revealed that the bra the little girl was wearing contained silver microfibers (SMF). Testing found that the eddy currents generated by this material in the MRI environment produced localized heating, which in turn caused the burns.

Digital radiographs showing the metallic fiber content of a Boston Silver T-shirt, compared to radiographs of a normal cotton underwear. Source: Literature

Why some clothes?

Will there be silver fibers?

Silver microfibers are widely used in clothing and other textiles due to their unique antimicrobial properties. Silver has been known since ancient times for its antimicrobial properties, inhibiting the growth of bacteria, fungi and other microorganisms. These properties make silver microfibers an attractive material, especially in products that need to stay clean and reduce odors.

Several scientific studies have confirmed the antibacterial properties of silver particles and silver nanomaterials. One study showed that silver nanoparticles can effectively fight antibiotic-resistant bacteria, inhibiting bacterial growth by destroying bacterial cell membranes and interfering with their metabolic processes. Another study explored in detail the different mechanisms of action of silver ions and silver nanomaterials on bacteria and found that silver nanomaterials can destroy bacterial cells by generating reactive oxygen species (ROS).

There are many kinds of clothing containing silver microfibers, including sportswear, yoga pants, socks, underwear and medical textiles, etc. These clothes not only have the function of wicking moisture, but also reduce the growth of microorganisms through the antibacterial effect of silver, thus keeping the clothes fresh and hygienic.

Silver microfibers are usually added to clothing in the following ways:

Weaving process: Silver particles are embedded into the fibers during the weaving process so that they are evenly distributed throughout the fabric.

Coating technology: Silver particles are coated on the fiber surface and fixed on the fabric through a coating process.

Blended spinning process: Silver microfibers are mixed with other fibers to make the fabric have both the antibacterial properties of silver and the functions of other fibers.

Why Silver Fiber Clothing May

Does heat get generated during an MRI procedure?

MRI uses powerful magnetic fields and radio frequency pulses to create images of the inside of the human body. When silver fibers are exposed to the high-frequency electromagnetic field of MRI, eddy currents are induced within the metal fibers. These eddy currents are generated by electromagnetic induction and circulate within the metal, causing the currents to concentrate in certain areas, especially at fiber seams or where there is a high concentration of metal content.

Silver is a highly conductive metal, so even tiny eddy currents can generate significant heat. In addition, the distribution of silver fibers in clothing tends to form closed loops, which makes the eddy current effect more significant. When this heat cannot be dispersed quickly, it will accumulate where it touches the skin, causing local temperature rise and thus causing burns.

In addition, the radio frequency pulses used by MRI are used to excite hydrogen atoms in the human body to generate images. These radio frequency pulses are also absorbed by the metal fibers and converted into heat. This energy absorption and conversion process intensifies the heating effect of the metal fibers, causing the temperature to rise further.

To prevent similar incidents from happening again, scientists in the paper recommend that all patients undergoing MRI examinations should change into metal-free safety clothing provided by the hospital. After all, who knows if there are invisible metal fibers in the clothes? Otherwise, what is burned at that time is not calories...

References

[1]Hiroyuki Tokue et al. 'Unexpected magnetic resonance imaging burn injuries from jogging pants.' Radiology Case Reports, 2019.

[2]Edwards-Jones V. 'The benefits of silver in hygiene, personal care and healthcare.' Lett Appl Microbiol 49:147–152, 2009.

AJNR Am J Neuroradiol. 'Invisible Metallic Microfiber in Clothing Presents Unrecognized MRI Risk for Cutaneous Burn.'

Planning and production

Source: Bringing Science Home (id: steamforkids)

Author: Su Chengyu

Editor: Zhong Yanping

Proofread by Xu Lailinlin