Burn Caused By Metal Fiber Clothes Entering Into NMR

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An 11 year old girl underwent MRI examination due to scoliosis. There are no buttons, zippers or embroidery on the clothes. No metal can be seen by the naked eye.

Before entering the nuclear magnetic resonance room, we passed the handheld metal detector for screening.

During the process, the little girl complained that her right abdomen was burning. Later, a physical examination was carried out on the little girl, and it was found that her right abdomen and the wrist on the same side contacting her underwear had linear erythematous herpes. The diagnosis of dermatology consultation was second degree burn.

Further investigation found that the underwear worn by the little girl contained silver microfiber (SMF). The test found that the eddy current generated by this material in the MRI environment generated local heating, which led to burns.

Digital radiography shows the metal fiber content of Boston silver T-shirt.

Why do some clothes have silver fiber?

Silver micro fiber is widely used in clothing and other textiles because of its unique antibacterial properties. Silver has been known for its antibacterial properties since ancient times, which can inhibit the growth of bacteria, fungi and other microorganisms. These characteristics make silver microfiber an attractive

Many scientific studies have confirmed the antibacterial properties of silver particles and silver nanomaterials.

A study shows that silver nanoparticles can effectively resist antibiotic resistant bacteria, and inhibit bacterial growth by destroying bacterial cell membranes and interfering with their metabolic processes. Another study explored the different mechanisms of silver ions and silver nanomaterials on bacteria in detail, 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. These clothes can not only absorb moisture and sweat, but also reduce the growth of microorganisms through the antibacterial effect of silver, so as to keep the clothes fresh and hygienic 。

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

Textile process: In the textile process, silver particles are embedded into the fiber, 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 the coating process.

Blending process: the silver micro fiber is mixed with other fibers for weaving, so that the fabric has the antibacterial properties of silver and the functions of other fibers at the same time.

Norwex is one of the first brands to introduce silver microfiber into cleaning cloth and other textiles. Their products use the antibacterial properties of silver to improve the sanitary level of cleaning cloth and reduce the frequency of frequent cleaning. Norwex's antibacterial cleaning cloth can not only clean the surface efficiently, but also automatically inhibit the propagation of bacteria after use to keep the cloth clean.

Why might silver fiber clothing generate heat during MRI?

When the silver fiber is exposed to the high-frequency electromagnetic field of MRI, eddy currents will be induced in the metal fiber. These eddies are generated by electromagnetic induction. They circulate inside the metal, causing the current to concentrate in some areas, especially the fiber seams or the parts where the metal components are concentrated.

Silver is a highly conductive metal, so even small eddy currents can produce significant heat. In addition, the distribution of silver fiber in clothing is easy to form a closed loop, which will make the vortex effect more significant. When these heat cannot be dissipated quickly, it will accumulate at the place contacting the skin, leading to local temperature rise, thus causing burns.

In addition, the radio frequency pulse of MRI is used to excite hydrogen atoms in the human body to generate images. These RF pulses will also be absorbed by the metal fibers and converted into heat. This energy absorption and conversion process intensifies the heating effect of the metal fiber, which further increases the temperature.

In order to prevent similar events from happening again, it is recommended that all patients undergoing MRI should change into metal free safety clothing provided by the hospital. After all, who knows if there are invisible metal fibers in the clothes?