JOURNAL OF MAGNETIC RESONANCE IMAGING 41:858–860 (2015)
Case Report
Acupressure Magnets: A Possible MRI Hazard Jeffrey P. Otjen, MD,1* Kara Mallon, RT, R (MR),2 and Julie C. Brown, MDCM, MPH3 The use of magnets as a component of complementary and alternative medicine is increasingly common. Magnet therapy is used to treat a variety of conditions and often involves tiny magnets adhered to the skin. In auriculotherapy, magnets are placed in specific locations of the ear pinnae which represent particular parts of the body. While generally considered safe, these magnets have the potential to cause imaging problems and serious injury during MRI. We report a case of auriculotherapy magnets which escaped detection despite the use of screening forms and a walk-through metal detector. The magnets caused image artifact but no other patient harm. We recommend updating patient screening practices and educating providers placing therapeutic magnets and performing MRIs of this new potential MRI hazard. Key Words: magnet; magnet therapy; alternative medicine; auriculotherapy; acupressure; safety J. Magn. Reson. Imaging 2015;41:858–860. C 2014 Wiley Periodicals, Inc. V
METALLIC AND MAGNETIC items are known to interact with magnetic resonance imaging (MRI) scans, resulting in problems ranging from image degradation to burns, blindness, injuries or even death (1–4). Patients undergoing MRI are screened by history and/or metal detectors for internal or external metallic items. We report a case of a boy who had auricular acupressure magnets on both ears, which escaped identification despite use of a standard MRI screening questionnaire and a full body metal detector. CASE A 9-year-old boy with a history of juvenile inflammatory arthritis and jaw pain presented to the radiology department at our urban, tertiary children’s hospital
1 Seattle Children’s Hospital, Department of Radiology, University of Washington, Department of Radiology, Seattle, Washington, USA. 2 Seattle Children’s Hospital, Department of Radiology, Seattle, Washington, USA. 3 Seattle Children’s Hospital, University of Washington, Department of Pediatrics, Division of Emergency Medicine, Seattle, Washington, USA. *Address reprint requests to: J.P.O., 4800 Sand Point Way NE, Seattle, WA 98105. E-mail: [email protected] Received November 4, 2013; Accepted January 29, 2014. DOI 10.1002/jmri.24600 View this article online at wileyonlinelibrary.com. C 2014 Wiley Periodicals, Inc. V
for a routine outpatient MRI to evaluate his temporomandibular joints. Prior MRIs had been uneventful. His MRI screening form was filled out and reviewed by the technologist. His mother answered “no” to all relevant questions, including “magnetically activated implant or device”; “medication patch”; “shrapnel, bullet, BB”; and “any other foreign objects in your body.” The patient R Guardian (Metraalso stepped through a FerroguardV sens Ltd., IL) freestanding ferromagnetic detection system, a full-body metal detector, which gave no indication of metal present. The MRI scan was initiated on a 1.5 Tesla (T) Siemens Avanto MR, and during image acquisition the technologist noted artifact in the region of both ears, which was most pronounced on the fat-saturated T1 sequence (Fig. 1A). The scan was then halted. On questioning, the patient did not report any symptoms on or near his ears. Neither he nor his mother could think of anything that might have caused the artifact. The patient was then examined by the technologist, who found small disc-shaped magnets taped to each ear pinna and tragus, using skin-colored bandages. The patient’s mother subsequently recalled that these had been placed by an acupuncturist several days before the scan, as a treatment for his jaw pain. Once discovered, they were removed and the scan was repeated with no further incident. On further testing, the metal detector repeatedly failed to elicit a warning when these small magnets were passed through it, while successfully detecting other small metallic objects and otherwise functioning properly. This lack of detection may be related to the composition of the material or very small size of the objects. DISCUSSION Small, powerful magnets are increasingly available in a wide range of products, including toys, novelty items, jewelry, and tools (5–7). They are also increasingly used as part of acupressure and other complementary and alternative medicine therapies (8,9). Auriculotherapy, acupressure involving the ear pinnae, is used to treat a wide range of illnesses, painful conditions and other complaints (Fig. 1B). Its uses include gastrointestinal, respiratory, urinary and cardiovascular disease, acne vulgaris, arthritis, fibromyalgia, depression, weight loss and smoking cessation (10,11). Magnet therapy can also be used on many other body sites. A variety of magnets for
858
Acupressure Magnets, an MRI Hazard
859
Figure 1. A: Coronal T1 fat saturated images showing significant artifact in the region of the temporomandibular joints bilaterally (left image) which resolved after auriculotherapy magnets were removed (right image). Note the improved visualization of the right temporomandibular joint synovial enhancement without artifact (right image). B: Auriculotherapy magnets: the type of magnets worn by the patient, in similar positions (left); smaller spherical magnets, in positions typically used for weight loss (right). C: Auriculotherapy and other small acupressure magnets.
magnet therapy, acupressure and auriculotherapy are commercially available, in a range of shapes, sizes and strengths (Fig. 1C). They are often very small and difficult to visualize due to their use with small, skincolored bandages.
Patients may not be aware that these therapeutic objects are metallic or magnetic, and may not be warned of the potential for interaction with MRI. They may also fail to recall these objects at the time of MRI, if not specifically prompted to consider them.
860
Screening questionnaires for MRI imaging typically include many questions aimed at identifying possible metallic and magnetic foreign bodies. However, our screening questionnaire and others we reviewed in the literature (12,13) and online did not include questions specifically aimed at identifying magnets used for magnet therapy. Despite the screening form and metal detector, and even with specific prompting for objects near the ears, neither the patient nor his mother recalled these magnets were present. In this case, the only adverse event was the poor initial image quality and extended scan time. However, given the position of the magnets and propensity for metallic and magnetic items to move or heat during the scan, there was the potential for significant injury, particularly to the ears. For instance, dislodgement of a magnet into the external canal could lead to damage to the tympanic membrane or ossicles. There is no way to predict what type of forces or heat might be generated within the magnetic fields created during MRI, due to multiple different types available (see Fig. 1C), and lack of available information about their magnet strength, composition, or uniformity. Paper clips and hairpins near a 1.5T magnet can reach speeds of 40 mph, and metallic tattoos or permanent eye liner containing iron oxide can heat sufficiently to cause burns (14). In addition, image artifacts from metal can easily mask or mimic disease. These tiny magnets also risk being ingested, particularly if used in younger patients. An unidentified intestinal magnet would be an even greater MRI hazard. It is important to consider the risk of ingestion, particularly in patients less than 6-years of age (3). Patients who report using magnet therapy should be asked if they have ever swallowed a magnet. If a magnet is missing and/or may have been ingested, a screening radiograph may be warranted. Because of this case, we have changed practice at our institution to prevent a similar event in the future. When placing these objects, our Anesthesia / Pain Management providers now routinely advise patients receiving acupressure with metal or magnets to remove these objects before MRI (although in this case they were placed by an outside practitioner). We have also added the specific question “acupressure magnet therapy” to our MRI screening questionnaire.
Otjen et al.
In conclusion, magnetic and metallic objects can cause problems with MR scans ranging from negligible to life threatening. The increasing use of magnets in acupressure and as magnet therapy may result in an increase in adverse events. These risks can be minimized by improved patient education, specific screening questions before MRI, and increased awareness of the risk by technologists, radiologists, and providers using these treatment modalities. REFERENCES 1. Chaljub G, Kramer LA, Johnson RF III, Johnson RF Jr, Singh H, Crow WN. Projectile cylinder accidents resulting from the presence of ferromagnetic nitrous oxide or oxygen tanks in the MR suite. AJR Am J Roentgenol 2001;177:27–30. 2. Chen D.Boy, 6, dies of skull injury during MRI. New York Times. July 31, 2001:B1, B5. 3. Klucznik RP, Carrier DA, Pyka R, Haid RW. Placement of a ferromagnetic intracerebral aneurysm clip in a magnetic field with a fatal outcome. Radiology 1993;187:855–856. 4. Kelly WM, Paglen PG, Pearson JA, San Diego AG, Soloman MA. Ferromagnetism of intraocular foreign body causes unilateral blindness after MR study. AJNR Am J Neuroradiol 1986;7:243–245. 5. Consumer Product Safety Commission (16 CFR Park 1240);Safety Standard for Magnet Sets, Volume 77, Number 171, 53781 (September 4, 2012). 6. Hussain SZ, Bousvaros A, Gilger M, et al. Management of ingested magnets in children. J Pediatr Gastroenterol Nutr 2012; 55:239–242. 7. Silverman JA, Brown JC, Willis MM, Ebel BE. Increase in pediatric magnet-related foreign bodies requiring emergency care. Ann Emerg Med 2013;62:604–608. 8. Health Library.Magnet therapy. Health Library [Internet]. 2012:9/ 4/13. Available at: http://healthlibrary.epnet.com/print.aspx?to ken¼de6453e6-8aa2-4e28-b56c-5e30699d7b3c&ChunkIID¼33778. Accessed October 10, 2013. 9. NYU Langone Medical Center.Magnet therapy [Internet]. Available at: http://www.med.nyu.edu/content?ChunkIID¼33778. Accessed September 4, 2013. 10. Back and Neck Pain Center [Internet]. Available at: http://www. backneckpaincenter.com/auriculotherapy. Accessed September 4, 2013. 11. Paradigm Publications_ModChiEarAcu [Internet]. Available at: http://www.paradigm-pubs.com. Accessed September 4, 2013. 12. Elster AD, Link KM, Carr JJ. Patient screening prior to MR imaging: A practical approach synthesized from protocols at 15 U. S. medical centers. AJR Am J Roentgenol 1994;162:195–199. 13. Shellock FG, Crues JV. MR procedures: Biologic effects, safety, and patient care. Radiology 2004;232:635–652. 14. VA National Center for Patient Safety.Preventing accidents and injuries in the MRI suite, February 14, 2008 [Internet]. Available at: http://www.patientsafety.va.gov/SafetyTopics/ mrihazardsummary.html. Accessed September 4, 2013.
Case Report
Acupressure Magnets: A Possible MRI Hazard Jeffrey P. Otjen, MD,1* Kara Mallon, RT, R (MR),2 and Julie C. Brown, MDCM, MPH3 The use of magnets as a component of complementary and alternative medicine is increasingly common. Magnet therapy is used to treat a variety of conditions and often involves tiny magnets adhered to the skin. In auriculotherapy, magnets are placed in specific locations of the ear pinnae which represent particular parts of the body. While generally considered safe, these magnets have the potential to cause imaging problems and serious injury during MRI. We report a case of auriculotherapy magnets which escaped detection despite the use of screening forms and a walk-through metal detector. The magnets caused image artifact but no other patient harm. We recommend updating patient screening practices and educating providers placing therapeutic magnets and performing MRIs of this new potential MRI hazard. Key Words: magnet; magnet therapy; alternative medicine; auriculotherapy; acupressure; safety J. Magn. Reson. Imaging 2015;41:858–860. C 2014 Wiley Periodicals, Inc. V
METALLIC AND MAGNETIC items are known to interact with magnetic resonance imaging (MRI) scans, resulting in problems ranging from image degradation to burns, blindness, injuries or even death (1–4). Patients undergoing MRI are screened by history and/or metal detectors for internal or external metallic items. We report a case of a boy who had auricular acupressure magnets on both ears, which escaped identification despite use of a standard MRI screening questionnaire and a full body metal detector. CASE A 9-year-old boy with a history of juvenile inflammatory arthritis and jaw pain presented to the radiology department at our urban, tertiary children’s hospital
1 Seattle Children’s Hospital, Department of Radiology, University of Washington, Department of Radiology, Seattle, Washington, USA. 2 Seattle Children’s Hospital, Department of Radiology, Seattle, Washington, USA. 3 Seattle Children’s Hospital, University of Washington, Department of Pediatrics, Division of Emergency Medicine, Seattle, Washington, USA. *Address reprint requests to: J.P.O., 4800 Sand Point Way NE, Seattle, WA 98105. E-mail: [email protected] Received November 4, 2013; Accepted January 29, 2014. DOI 10.1002/jmri.24600 View this article online at wileyonlinelibrary.com. C 2014 Wiley Periodicals, Inc. V
for a routine outpatient MRI to evaluate his temporomandibular joints. Prior MRIs had been uneventful. His MRI screening form was filled out and reviewed by the technologist. His mother answered “no” to all relevant questions, including “magnetically activated implant or device”; “medication patch”; “shrapnel, bullet, BB”; and “any other foreign objects in your body.” The patient R Guardian (Metraalso stepped through a FerroguardV sens Ltd., IL) freestanding ferromagnetic detection system, a full-body metal detector, which gave no indication of metal present. The MRI scan was initiated on a 1.5 Tesla (T) Siemens Avanto MR, and during image acquisition the technologist noted artifact in the region of both ears, which was most pronounced on the fat-saturated T1 sequence (Fig. 1A). The scan was then halted. On questioning, the patient did not report any symptoms on or near his ears. Neither he nor his mother could think of anything that might have caused the artifact. The patient was then examined by the technologist, who found small disc-shaped magnets taped to each ear pinna and tragus, using skin-colored bandages. The patient’s mother subsequently recalled that these had been placed by an acupuncturist several days before the scan, as a treatment for his jaw pain. Once discovered, they were removed and the scan was repeated with no further incident. On further testing, the metal detector repeatedly failed to elicit a warning when these small magnets were passed through it, while successfully detecting other small metallic objects and otherwise functioning properly. This lack of detection may be related to the composition of the material or very small size of the objects. DISCUSSION Small, powerful magnets are increasingly available in a wide range of products, including toys, novelty items, jewelry, and tools (5–7). They are also increasingly used as part of acupressure and other complementary and alternative medicine therapies (8,9). Auriculotherapy, acupressure involving the ear pinnae, is used to treat a wide range of illnesses, painful conditions and other complaints (Fig. 1B). Its uses include gastrointestinal, respiratory, urinary and cardiovascular disease, acne vulgaris, arthritis, fibromyalgia, depression, weight loss and smoking cessation (10,11). Magnet therapy can also be used on many other body sites. A variety of magnets for
858
Acupressure Magnets, an MRI Hazard
859
Figure 1. A: Coronal T1 fat saturated images showing significant artifact in the region of the temporomandibular joints bilaterally (left image) which resolved after auriculotherapy magnets were removed (right image). Note the improved visualization of the right temporomandibular joint synovial enhancement without artifact (right image). B: Auriculotherapy magnets: the type of magnets worn by the patient, in similar positions (left); smaller spherical magnets, in positions typically used for weight loss (right). C: Auriculotherapy and other small acupressure magnets.
magnet therapy, acupressure and auriculotherapy are commercially available, in a range of shapes, sizes and strengths (Fig. 1C). They are often very small and difficult to visualize due to their use with small, skincolored bandages.
Patients may not be aware that these therapeutic objects are metallic or magnetic, and may not be warned of the potential for interaction with MRI. They may also fail to recall these objects at the time of MRI, if not specifically prompted to consider them.
860
Screening questionnaires for MRI imaging typically include many questions aimed at identifying possible metallic and magnetic foreign bodies. However, our screening questionnaire and others we reviewed in the literature (12,13) and online did not include questions specifically aimed at identifying magnets used for magnet therapy. Despite the screening form and metal detector, and even with specific prompting for objects near the ears, neither the patient nor his mother recalled these magnets were present. In this case, the only adverse event was the poor initial image quality and extended scan time. However, given the position of the magnets and propensity for metallic and magnetic items to move or heat during the scan, there was the potential for significant injury, particularly to the ears. For instance, dislodgement of a magnet into the external canal could lead to damage to the tympanic membrane or ossicles. There is no way to predict what type of forces or heat might be generated within the magnetic fields created during MRI, due to multiple different types available (see Fig. 1C), and lack of available information about their magnet strength, composition, or uniformity. Paper clips and hairpins near a 1.5T magnet can reach speeds of 40 mph, and metallic tattoos or permanent eye liner containing iron oxide can heat sufficiently to cause burns (14). In addition, image artifacts from metal can easily mask or mimic disease. These tiny magnets also risk being ingested, particularly if used in younger patients. An unidentified intestinal magnet would be an even greater MRI hazard. It is important to consider the risk of ingestion, particularly in patients less than 6-years of age (3). Patients who report using magnet therapy should be asked if they have ever swallowed a magnet. If a magnet is missing and/or may have been ingested, a screening radiograph may be warranted. Because of this case, we have changed practice at our institution to prevent a similar event in the future. When placing these objects, our Anesthesia / Pain Management providers now routinely advise patients receiving acupressure with metal or magnets to remove these objects before MRI (although in this case they were placed by an outside practitioner). We have also added the specific question “acupressure magnet therapy” to our MRI screening questionnaire.
Otjen et al.
In conclusion, magnetic and metallic objects can cause problems with MR scans ranging from negligible to life threatening. The increasing use of magnets in acupressure and as magnet therapy may result in an increase in adverse events. These risks can be minimized by improved patient education, specific screening questions before MRI, and increased awareness of the risk by technologists, radiologists, and providers using these treatment modalities. REFERENCES 1. Chaljub G, Kramer LA, Johnson RF III, Johnson RF Jr, Singh H, Crow WN. Projectile cylinder accidents resulting from the presence of ferromagnetic nitrous oxide or oxygen tanks in the MR suite. AJR Am J Roentgenol 2001;177:27–30. 2. Chen D.Boy, 6, dies of skull injury during MRI. New York Times. July 31, 2001:B1, B5. 3. Klucznik RP, Carrier DA, Pyka R, Haid RW. Placement of a ferromagnetic intracerebral aneurysm clip in a magnetic field with a fatal outcome. Radiology 1993;187:855–856. 4. Kelly WM, Paglen PG, Pearson JA, San Diego AG, Soloman MA. Ferromagnetism of intraocular foreign body causes unilateral blindness after MR study. AJNR Am J Neuroradiol 1986;7:243–245. 5. Consumer Product Safety Commission (16 CFR Park 1240);Safety Standard for Magnet Sets, Volume 77, Number 171, 53781 (September 4, 2012). 6. Hussain SZ, Bousvaros A, Gilger M, et al. Management of ingested magnets in children. J Pediatr Gastroenterol Nutr 2012; 55:239–242. 7. Silverman JA, Brown JC, Willis MM, Ebel BE. Increase in pediatric magnet-related foreign bodies requiring emergency care. Ann Emerg Med 2013;62:604–608. 8. Health Library.Magnet therapy. Health Library [Internet]. 2012:9/ 4/13. Available at: http://healthlibrary.epnet.com/print.aspx?to ken¼de6453e6-8aa2-4e28-b56c-5e30699d7b3c&ChunkIID¼33778. Accessed October 10, 2013. 9. NYU Langone Medical Center.Magnet therapy [Internet]. Available at: http://www.med.nyu.edu/content?ChunkIID¼33778. Accessed September 4, 2013. 10. Back and Neck Pain Center [Internet]. Available at: http://www. backneckpaincenter.com/auriculotherapy. Accessed September 4, 2013. 11. Paradigm Publications_ModChiEarAcu [Internet]. Available at: http://www.paradigm-pubs.com. Accessed September 4, 2013. 12. Elster AD, Link KM, Carr JJ. Patient screening prior to MR imaging: A practical approach synthesized from protocols at 15 U. S. medical centers. AJR Am J Roentgenol 1994;162:195–199. 13. Shellock FG, Crues JV. MR procedures: Biologic effects, safety, and patient care. Radiology 2004;232:635–652. 14. VA National Center for Patient Safety.Preventing accidents and injuries in the MRI suite, February 14, 2008 [Internet]. Available at: http://www.patientsafety.va.gov/SafetyTopics/ mrihazardsummary.html. Accessed September 4, 2013.
