Magnetic resonance safety assessment of a new trend: magnetic eyelashes

Received: 21 May 2020 | Revised: 21 May 2020 | Accepted: 25 May 2020 DOI: 10.1002/acm2.12952 LETTER TO THE EDITOR Magnetic resonance safety assessment of a new trend: magnetic eyelashes 1 | INTRODUCTION the field strength is within 20 percent of its maximum value along z, as described in Ref. [2]. Although the document provided by the One type of cosmetic that has gained recent popularity is the mag- manufacturer of the scanner did not have isogradient lines in this netic false eyelash. Some of these magnetic eyelashes are placed region, the spatial gradient forms a plateau centered at about (x, y, onto magnetic eyeliner applied to eye lids, while others come in z) = (0, 0, 830) mm with values ranging from 3 to 5 T/m. However, pairs and clamp around the natural eyelashes. This presents potential when a magnetic eyelash was brought close to this point, it was safety hazards in the magnetic resonance imaging (MRI) environ- pulled toward the wall of the bore (i.e. away from the bore axis), ment. This is because patients may not deem it necessary to disclose leading to a deflection angle that was more than 90 degrees. There- this type of cosmetic, the standard MR screening forms often fail to fore, the measurement location was chosen as (x, y, z) = (0, 0, 1078) capture these accessories, and the eyelashes may not be readily mm, where the value of the isogradient line was available and noticed by the technologists. reported as 3 T/m. The magnetic field strength at this location was MRI artifacts caused by magnetic eyelashes were reported <1 T. Given that common commercial permanent magnets like neo- previously.1 However, in this study, we used industry standard dymium magnets do not become saturated at such low magnetic testing methods specifically to examine the projectile risk. We field strengths,4 it is reasonable to assume that the deflection force quantified the deflection force experienced by magnetic eye- was proportional to the product of the field strength and the spatial lashes from various manufacturers. All tested products produced field gradient. large deflections, indicative of significant magnetic forces. The In accordance with the ASTM standard,2 each piece of magnetic translational forces were so strong that other effects (such as eyelash was deflection‐tested three times. The weights of the strings rotational forces, heating, and artifacts) could only be tested in a were also recorded. The magnetically induced deflection force was manner that is inconsistent with how a patient would present in calculated using the mean deflection angle. a usual clinical setting. The eyelashes of some brands — Lash’d Up™ (large piece), Pinpoxe®, Ardell®, and Lamiya (both pieces) — showed bending, related to the magnet base consisting of multiple small magnets 2 | MATERIALS AND METHODS rather than a single continuous piece. Furthermore, the string length required to knot the string both at the protractor and the magnetic All deflection tests were performed on a 3‐Tesla MR scanner (MR eyelash showed some variation. Consequently, for each eyelash, the component, Biograph mMR, Siemens Healthcare, Erlangen, Germany) location of the protractor was adjusted until the eyelash reached the following the guidelines listed in ASTM F2052‐15.2 Because it was location of measurement cited above, making the lengths of the presumed that the magnetic eyelashes would not remain in place as strings irrelevant. Due to the tilting of some magnetic eyelashes and the subject moved into the isocenter of the bore, no heating or tor- in order to prevent the lash‐component of the eyelash from touching que testing was performed. the ruler (which was fixed at z = 1078 mm), the eyelashes were kept Eyelashes from six brands were tested: Arishine®, Lash’d Up™, within a few millimeters of the target location (x, y, z) = (0, 0, Pinpoxe®, Lamix, Ardell®, and Lamiya [cf. Fig. 1(a)]. Arishine® and 1078) mm. It is worth noting that the spatial gradient values change Lamix came with an eyeliner applicator. The material composition of on a more macro scale (fractions of meters), so a margin of a few the magnetic eyelashes was not publically available. However, they millimeters exerts only a negligible effect. were all made of permanent magnets, which were most probably neodymium magnets.3 Figure 1(b) exhibits the magnetically induced deflection force 3 | RESULTS measurement configuration, while Figure 1(c) depicts the physical coordinate system of the scanner. Initially, we intended to do the Figure 1(d) lists the measurement results. The measured deflection test at the location within the scanner where the spatial gradient of angles were similar across different brands. ---------------------------------------------------------------------------------------------------------------------------------------------------------------------This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2020 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine. J Appl Clin Med Phys 2020; 21:8:323–325 wileyonlinelibrary.com/journal/jacmp | 323 324 | LETTER TO THE EDITOR F I G . 1 . (a) Magnetic eyelash brands that were tested. The Lash'd Up™ and Lamiya sets contain two different sizes of eyelashes for clasping; therefore, both sizes were tested. (b) The setup for magnetically induced deflection force measurement. The foam padding (orange) provides support for the protractor (yellow) to keep it straight. The dashed blue line indicates the z‐axis of the scanner. The string (red) is tied to the protractor and can rotate freely while holding the eyelash (black). The angle between the vertical green dash‐dot line and the string yields the deflection angle. (c) Diagram showing scanner coordinates. (d) Magnetically induced deflection force measurements for each make of magnetic eyelash. α1 , α2 , and α3 are the deflection angles obtained by repeating the measurement three times. α is the average of these angles and was used for the calculation of the deflection force Fm . LETTER TO THE | EDITOR 4 | DISCUSSION With the deflection angles being much larger than 45°, the results confirm that ferromagnetic eyelashes are MR unsafe and should 325 ACKNOWLEDGMENTS The authors thank Gwyneth A. McDonald for her advice in the selection of magnetic eyelash brands. be removed before entering Zone III, the space before entering the MRI scanner room.5 Furthermore, with the deflection angles being similar across different brands, the heavier magnetic eyelashes are expected to experience a larger projectile effect. Finally, CONFLICT OF INTEREST The authors have no conflict of interest to disclose. given the effect of the spatial gradient field component of the Cihat Eldeniz1 attraction force, the projectile effect can be significant, even at Trevor Andrews1 1.5 T. Uday Krishnamurthy2 It is worth noting that the weights of the strings were more than Lamyaa Aljaafari3 1% of those of the eyelashes, which were extremely light‐weight by Glenn Foster1 design. This exceeds the limit recommended by the ASTM standard Tammie L. S. Benzinger1 and thus requires an explanation.2 The excess weight would be a Hongyu An1 concern if the deflection angles were small since the string weight would be suspected to shadow the true deflection forces. However, in our study, it strengthens the case against magnetic eyelashes Pamela K. Woodard1 1 Mallinckrodt Institute of Radiology,Washington University School of Medicine, St. Louis, MO, USA because the deflection angles were close to 90° despite this additional load. If it were feasible to use extremely light strings, the deflection angles would be larger. 2 Siemens Healthineers, St. Louis, MO, USA 3 Department of Medical Imaging and Radiation Therapeutics, Saint Louis University, St. Louis, MO, USA Failing the deflection test does not make a piece of equipment MR unsafe in and of itself; nevertheless, near the MRI scanner, the Author to whom correspondence should be addressed. Cihat Eldeniz eyelashes can rapidly become a moving projectile as close as mil- E‐mail: cihat.eldeniz@wustl.edu; Telephone: 314‐747‐9603. limeters from the orbit of the eye and hence become a safety concern. In addition, even if they do not become a direct hazard to the patient, small ferromagnetic objects that get pulled into the MR system can remain there, or lodge within a receiving coil or accessory, potentially resulting in artifacts that may masquerade as pathology. Moreover, they could be relocated to hard‐to‐check areas, and troubleshooting could involve substantial scanner downtime. The magnetic eyeliner associated with some of these eyelashes are allowed to contain synthetic iron oxide under the current regulations of the FDA, 21 CFR §73.2250. It has been reported that, even with tattooed eyeliners that typically contain iron oxide, adverse events are unlikely, transient, and mild.6 However, like the false eyelashes themselves, magnetic eyeliners should be removed prior to the scan in order to ensure safety. REFERENCES 1. Slonimsky E, Mamourian A. Magnetic eyelashes: a new source of MRI artifacts. Am J Roentgenol. 2019;213:983–985. 2. ASTM F2052‐15. Standard Test Method for Measurement of Magnetically Induced Displacement Force on Medical Devices in the Magnetic Resonance Environment (ASTM International, West Conshohocken, PA, 2015, n.d.). 3. Stoka K. Non‐adhesive false eyelash system and method, US20190297979A1; 2019. 4. Constantinides S. The elements of magnetics. MRS Online Proc Libr Arch. 2013;1492:35–46. 5. Kanal E, Bell C, Borgstede JP, et al. ACR guidance document on MR safe practices: 2013. J Magn Reson Imaging. 2013;37:501–530. 6. Tope WD, Shellock FG. 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