Default.asp?SafetyInformationOrder=Sorter_Subject&SafetyInformationDir=ASC&SafetyInfoID=290
 mri_brain_scan
 Default.asp
 GenPg.asp?pgname=Disclaimer
 TheList_search.asp
 SafetyInfog.asp
 GenPg.asp?pgname=ScreeningForm
 GenPg.asp?pgname=ProductTesting
 GenPg.asp?pgname=OrderingBooks
 GenPg.asp?pgname=Lectures
 GenPg.asp?pgname=AboutDrShellock
 PriorityEmail.asp
 
 mri_brain_scan
 

                                            Safety Information Article
                      Information on this page is limited by the terms of our Disclaimer.  Please Read!

       Bioeffects of Static Magnetic Fields 

The introduction of magnetic resonance (MR) technology as a clinical imaging modality in the early 1980s is responsible for a substantial increase in human exposure to strong static magnetic fields. Most clinical MR systems in use today operate at fields ranging from 0.2- to 3-Tesla. According to the guidelines from the U.S. Food and Drug Administration, clinical MR systems using static magnetic fields up to 8.0-Tesla are considered a “non-significant risk” for adult patients. The exposure of research subjects to fields above this level requires approval of the research protocol by an Institutional Review Board and the informed consent of the subjects.

Currently, the most powerful MR system used for human subjects operates at 9.4-Tesla, but there are plans to develop even higher field strength scanners (e.g., greater than 11-Tesla). Several investigations now describe physiologic findings obtained in human subjects, including volunteers, patients, and workers relative to exposures to the 9.4-Tesla MR system. For the short-term exposures experienced by volunteers and patients, no readily demonstrated health risks were identified. However, a study conducted to evaluate sensory symptoms and vestibular function in workers exposed to the 9.4-Tesla MR system revealed that all participants noted sensory symptoms related to the exposure. The investigators concluded that, while the workers experienced sensory symptoms, it is unclear whether long-term vestibular damage or other changes occurred. The higher rates of vestibular changes may argue for improved worker surveillance and exposure control.

With respect to short-term exposures, the available information that pertains to the effects of static magnetic fields on biological tissues is extensive. Investigations include studies on alterations in cell growth and morphology, cell reproduction and teratogenicity, DNA structure and gene expression, pre- and post-natal reproduction and development, blood brain barrier permeability, nerve activity, cognitive function and behavior, cardiovascular dynamics, hematological indices, temperature regulation, circadian rhythms, immune responsiveness, neurological processing of visual and auditory information, and other biological processes. The majority of these studies concluded that exposures to static magnetic fields produce no substantial or harmful bioeffects. Although there have been reports of potentially injurious effects of static magnetic fields on isolated cells or organisms, no effect has been verified or firmly established as a scientific fact. The documented serious injuries and few fatalities that have occurred with MR system magnets were in association with the inadvertent introduction or presence of ferromagnetic objects (e.g., oxygen tanks, wheelchairs, aneurysm clips, etc.) into the MR environment.

Regarding the effects of long-term exposures to static magnetic fields, there are several physical mechanisms of interaction between tissues and static magnetic fields that could theoretically lead to pathological changes in human subjects. However, quantitative analysis of these mechanisms indicates that they are below the threshold of significance with respect to long-term, adverse bioeffects.

Presently, the peer-reviewed literature does not contain carefully controlled studies that support the absolute safety of chronic exposure to powerful magnetic fields. With the increased clinical use of interventional MR procedures, there is a critical need for such investigations. Thus, several groups are now directing attention to performing these important studies and preliminary results have appeared in the literature.

In addition, although there is no evidence for a cumulative effect of magnetic field exposure on health, further studies of the exposed populations (MR healthcare professionals, patients that undergo repeat studies, interventional MR users, etc.) will help establish guidelines for occupational and patient exposures to powerful static magnetic fields. Recently, the results of several investigations have been published that have addressed occupational exposures to MR systems including those operating at 1.5-, 3-, and 7-Tesla.

REFERENCES

Acri G, et al. Evaluation of occupational exposure in magnetic resonance sites. Radiol Med 2014;119:208-13.

Atkinson IC, et al. Safety of human MRI at static fields above the FDA 8 T guideline: Sodium imaging at 9.4 T does not affect vital signs or cognitive ability. J Magn Reson Imag 2007;26:1222-7.

Atkinson IC, et al. Vital signs and cognitive function are not affected by 23-sodium and 17-oxygen magnetic resonance imaging of the human brain at 9.4 T. J Magn Reson Imag 2010;32:82-7.

Besson J, et al. Cognitive evaluation following NMR imaging of the brain. Journal of Neurology, Neurosurgery, and Psychiatry 1984;47:314-316.

Bongers S, et al. Retrospective assessment of exposure to static magnetic fields during production and development of magnetic resonance imaging systems. Ann Occup Hyg 2014;58:85-102.

Bongers S, et al. Exposure to static magnetic fields and risk of accidents among a cohort of workers from a medical imaging device manufacturing facility. Magn Reson Med 2015 [Epub ahead of print].

Brockway J, Bream P. Does memory loss occur after MR imaging? J Magn Reson Imag 1992;2:721-728.

Brody A, et al. Induced alignment of flowing sickle erythrocytes in a magnetic field: A preliminary report. Investigative Radiology 1985;20:560-566.

Brody A, et al. Preservation of sickle cell blood flow pattern(s) during MR imaging: An in vivo study. Am J Roentgenol 1988;151:139-141.

Budinger TF. Nuclear magnetic resonance (NMR) in vitro studies: Known thresholds for health effects. J Comput Assisted Tomog 1981;5:800-811.

Cavin ID, et al. Thresholds for perceiving metallic taste at high magnetic field. J Magn Reson Imag 2007;26:1357-61.

Chakeres DW, de Vocht F. Static magnetic field effects on human subjects related to magnetic resonance imaging. Prog Biophys Mol Biol 2005;87:255-265.

de Vocht F, et al. Acute neurobehavior effects of exposure, health complaints and cognitive performance among employees of an MRI scanners manufacturing department. J Magn Reson Imag 2006;23:197-204.

de Vocht F, et al. Acute neurobehavior effects of exposure to static magnetic fields: Analysis of exposure-response relations. J Magn Reson Imag 2006;23:291-297.

de Vocht F, et al. Cognitive effects of head-movements in stray fields generated by a 7 Tesla whole-body MRI magnet. Bioelectromagnetics 2007;28:247-55.

Feychting M. Health effects of static magnetic fields: A review of the epidemiological evidence. Prog Biophys Mol Biol 2005;87:241-6.

Franco G, et al. Focusing ethical dilemmas of evidence-based practice in SMF-exposed MRI-workers: A qualitative analysis. Int Arch Occup Environ Health 2010;83:417-21.

Fuentes MA, et al. Analysis and measurements of magnetic field exposures for healthcare workers in selected MR environments. IEEE Trans Biomed Eng 2008;55:1355-64.

Ghodbane S, et al. Bioeffects of static magnetic fields: Oxidative stress, genotoxic effects, and cancer studies. Biomed Res Int 2013;2013:602987.

Glover PM, et al. Magnetic-field-induced vertigo: A theoretical and experimental investigation. Bioelectromagnetics 2007;28:349-61.

Gungor HR, et al. Are there any adverse effects of static magnetic field from magnetic resonance imaging devices on bone health of workers? Eklem Hastalik Cerrahisi 2014;25:36-41.

Hansson Mild K, et al. Exposure classification of MRI workers in epidemiological studies. Bioelectromagnetics 2013;24:81-4.

Hartwig V, et al. Biological effects and safety in magnetic resonance imaging: A review. Int J Environ Res Public Health 2009;6:1778-98.

Heinrich A, et al. Women are more strongly affected by dizziness in static magnetic fields of magnetic resonance imaging scanners. Neuroreport 2014;25:1081-4.

Heinrich A, et al. Effects of static magnetic fields on cognition, vital signs, and sensory perception: A meta-analysis. J Magn Reson Imag 2011;34:758–763.

Heinrich A, et al. Cognition and sensation in very high static magnetic fields: A randomized case-crossover study with different field strengths. Radiology 2013;266:236-45.

Heinrich A, et al. Women are more strongly affected by dizziness in static magnetic fields of magnetic resonance imaging scanners. Neuroreport 2014;25:1081-4.

Hong CZ, Shellock FG. Short-term exposure to a 1.5 Tesla static magnetic field does not effect somato-sensory evoked potentials in man. Magnetic Resonance Imaging 1989;8:65-69.

Hsieh CH, et al. Deleterious effects of MRI on chondrocytes. Osteoarthritis Cartilage. 2008;16:343-51.

Innis NK, et al. Behavioral effects of exposure to nuclear magnetic resonance imaging: II. Spatial memory tests. Magnetic Resonance Imaging 1986;4:281-284.

International Electrotechnical Commission (IEC), Medical Electrical Equipment, Particular requirements for the safety of magnetic resonance equipment for medical diagnosis, International Standard IEC 60601-2-33, 2002.

International Commission on Non-Ionizing Radiation Protection (ICNIRP) statement, medical magnetic resonance procedures: Protection of patients. Health Physics 2004;87:197-216.

Kangarlu A, et al. Cognitive, cardiac, and physiological safety studies in ultra high field magnetic resonance imaging. Magnetic Resonance Imaging 1999;17:1407-1416.

Kannala S, et al. Occupational exposure measurements of static and pulsed gradient magnetic fields in the vicinity of MRI scanners. Phys Med Biol 2009;54:2243-57.

Karpowicz J, et al. Exposure to static magnetic field and health hazards during the operation of magnetic resonance scanners. Med Pr. 2011;62:309-21.

Karpowicz J, et al. Measures of occupational exposure to time-varying low frequency magnetic fields of non-uniform spatial distribution in the light of international guidelines and electrodynamic exposure effects in the human body. Med Pr. 2012;63:317-28.

Karpowicz J, Gryz K. Health risk assessment of occupational exposure to a magnetic field from magnetic resonance imaging devices. Int J Occup Saf Ergon 2006;12:155-67.

Kay H, Herfkens R, Kay B. Effect on magnetic resonance imaging on Xenopus Laevis embryogenesis. Magnetic Resonance Imaging 1988;6:501-506.

Laszlo J, Gyires K. 3 T homogeneous static magnetic field of a clinical MR significantly inhibits pain in mice. Life Sci 2009;84:12-7.

McRobbie DW. Occupational exposure in MRI. Br J Radiol 2012;85:293-312.

Muller S, Hotz M. Human brainstem auditory evoked potentials (BAEP) before and after MR examinations. Magnetic Resonance in Medicine 1990;16:476-480.

Nojima I, et al. Static magnetic field can transiently alter the human intracortical inhibitory system. Clin Neurophysiol 2015 [Epub ahead of print].

Ossenkopp KP, et al. Behavioral effects of exposure to nuclear magnetic resonance imaging: I. Open-field avoidance behavior an passive avoidance learning in rats. Magnetic Resonance Imaging 1986;4:275-280.

Patel M, et al. Pilot study investigating the effect of the static magnetic field from a 9.4-T MRI on the vestibular system. J Occup Environ Med 2008;50:576-83.

Prasad N, Wright D, Ford J, Thornby J. Safety of 4-T MR imaging: Study of effects on developing frog embryos. Radiology 1990;174:251-253.

Rauschenberg J, et al. Multicenter study of subjective acceptance during magnetic resonance imaging at 7 and 9.4 T. Invest Radiol 2014;49:249-59.

Sakurai T, Terashima S, Miyakoshi J. Effects of strong static magnetic fields used in magnetic resonance imaging on insulin-secreting cells. Bioelectromagnetics. Bioelectromagnetics 2009;30:1-8.

Schaap K, et al. Inventory of MRI applications and workers exposed to MRI-related electromagnetic fields in the Netherlands. Eur J Radiol 2013;82:2279-85.

Schaap K, et al. Exposure to static and time-varying magnetic fields from working in the static magnetic stray fields of MRI scanners: A comprehensive survey in the Netherlands. Ann Occup Hyg 2014;58:1094-1110.

Schaap K, et al. Occupational exposure of healthcare and research staff to static magnetic stray fields from 1.5-7 Tesla MRI scanners is associated with reporting of transient symptoms. Occup Environ Med 2014;71:423-9.

Schaap K, et al. Work-related factors associated with occupational exposure to static magnetic stray fields from MRI scanners. Magn Reson Med 2015 [Epub ahead of print].

Schenck JF. Health effects and safety of static magnetic fields. In: Shellock FG, Editor. Magnetic Resonance Procedures: Health Effects and Safety. Boca Raton, FL: CRC Press, 2001; pp. 1-30.

Schenck JF. Safety of strong, static magnetic fields. J Magn Reson Imag 2000;12;2-19.

Schenck JF, et al. Human exposure to 4.0-Tesla magnetic fields in a whole-body scanner. Medical Physics 1992;19:1089-1098.

Schlamann M, et al. Exposure to high-field MRI does not affect cognitive function. J Magn Reson Imag 2010;31:1061-6.

Schlamann M, et al. Short term effects of magnetic resonance imaging on excitability of the motor cortex at 1.5T and 7T. Acad Radiol 2010;17:277-81.

Schwartz J, Crooks L. NMR imaging produces no observable mutations or cytotoxicity in mammalian cells. Am J Roentgenol 1982;139:583-585.

Schwenzer NF, et al. Do static or time-varying magnetic fields in magnetic resonance imaging (3.0 T) alter protein-gene expression?-A study on human embryonic lung fibroblasts. J Magn Reson Imag 2007;26:1210-5.

Schwenzer NF, et al. In vitro evaluation of magnetic resonance imaging at 3.0 Tesla on clonogenic ability, proliferation, and cell cycle in human embryonic lung fibroblasts. Invest Radiol 2007;42:212-217.

Shellock FG, Crues JV. MR procedures: Biologic effects, safety, and patient care. Radiology 2004;232:635-652.

Shellock FG, Schaefer DJ, Crues JV. Exposure to a 1.5 Tesla static magnetic field does not alter body and skin temperatures in man. Magnetic Resonance in Medicine 1989;1:371-375.

Shellock FG, Schaefer DJ, Gordon CJ. Effect of a 1.5 Tesla static magnetic field on body temperature of man. Magnetic Resonance in Medicine 1986;3:644-647.

Short W, et al. Alteration of human tumor cell adhesion by high-strength static magnetic fields. Investigative Radiology 1991;27:836-840.

Silva AK, Silva EL, Egito ES, Carrico AS. Safety concerns related to magnetic field exposure. Radiat Environ Biophys 2006;45:245-52.

Simmons A, Hakansson K. Magnetic resonance safety. Methods Mol Biol 2011;711:17-28.

Theysohn JM, et al. Vestibular effects of a 7 Tesla MRI examination compared to 1.5 T and 0 T in healthy volunteers. PLoS One 2014;9:e92104.

Tomasi DG, Wang R. Induced magnetic field gradients and forces in the human head in MRI. J Magn Reson Imag 2007;26:1340-5.

Toyomaki A, Yamamoto T. Observation of changes in neural activity due to the static magnetic field of an MRI scanner. J Magn Reson Imag 2007;26:1216-21.

U.S. Department of Health and Human Services, Food and Drug Administration, Center for Devices and Radiological Health, Criteria for Significant Risk Investigations of Magnetic Resonance Diagnostic Devices, Guidance for Industry and Food and Drug Administration Staff. June 20, 2014.

Valiron O, et al. Cellular disorders induced by high magnetic fields. J Magn Reson Imag 2005;22:334-340.

van Nierop LE, et al. Effects of magnetic stray fields from a 7 Tesla MRI scanner on neurocognition: A double-blind randomised crossover study. Occup Environ Med 2012;69:759-66.

van Nierop L, et al. Acute cognitive effects of MRI related magnetic fields: The role of vestibular sensitivity. Occup Environ Med 2014;71 Suppl 1:A16.

van Nierop LE, et al. Simultaneous exposure to MRI-related static and low-frequency movement-induced time-varying magnetic fields affects neurocognitive performance: A double-blind randomized crossover study.  Magn Reson Med 2015;74:840-9.  

Vaughan T, et al. 9.4-T human MRI: Preliminary results. Magn Reson Med 2006;56:1274-1282.

Vecchia P, Hietanen M, et al. Guidelines on limits of exposure to static magnetic fields. International Commission on Non-Ionizing Radiation Protection. Health Physics 2009;96:504-14.

Versluis MJ, et al. Subject tolerance of 7 T MRI examinations. J Magn Reson Imaging 2013;38:722-5.

Vijayalaxmi, et al. Magnetic resonance imaging (MRI): A review of genetic damage investigations. Mutat Res Rev Mutat Res 2015;764:51-63.

Vogl T, et al. Influence of magnetic resonance imaging on evoked potentials and nerve conduction velocities in humans. Invest Radiol 1991;26:432-437.

Von Klitzing L. Do static magnetic fields of NMR influence biological signals? Clin Phys Physiol Meas 1986;7:157-160.

Ward BK, et al. Vestibular stimulation by magnetic fields. Ann N Y Acad Sci 2015;1343:69-79.

Weintraub MI, et al. Biologic effects of 3 Tesla (T) MR imaging comparing traditional 1.5-T and 0.6-T in 1,023 consecutive outpatients. J Neuroimaging 2007;17:241-5.

Weiss M, et al. Bioeffects of high magnetic fields: A study using a simple animal model. Magnetic Resonance Imaging 1992;10:689-694.

Yamaguchi-Sekino S, et al. Biological effects of electromagnetic fields and recently updated safety guidelines for strong static magnetic fields. Magn Reson Med Sci 2011;10:1-10.

Yamaguchi-Sekino S, et al. Occupational exposure levels of static magnetic field during routine MRI examination in 3 T MR system. Bioelectromagnetics 2014;35:70-5.  

Yuh WTC, Ehrhardt JC, Fisher DJ, Shields RK, Shellock FG. Phantom limb pain induced in amputee by strong magnetic fields. J Magn Reson Imag 1992;2:221-223.

Zahedi Y, et al. Impact of repetitive exposure to strong static magnetic fields on pregnancy and embryonic development of mice. J Magn Reson Imaging 2014;39:691-9.

Zaremba LA. FDA guidance for magnetic resonance system safety and patient exposures: Current status and future considerations. In: Shellock FG, Editor. Magnetic Resonance Procedures: Health Effects and Safety. Boca Raton, FL: CRC Press, 2001; pp. 183-196.

Zaun G, et al. Repetitive exposure of mice to strong static magnetic fields in utero does not impair fertility in adulthood but may affect placental weight of offspring. J Magn Reson Imaging 2014;39:683-90.



_____________________________________________________________________________________
  (c) 2017 by Shellock R & D Services, Inc. and Frank G. Shellock, Ph.D. All Rights Reserved. All copyrights and pertinent trademarks are owned by Shellock R & D Services, Inc. and Frank G. Shellock, Ph.D. No part of the MRISAFETY.COM web site may be reproduced, stored in any retrieval system, or transmitted in any form or by any means, physical, electronic or otherwise, without the prior written permission of Shellock R & D Services, Inc. or Frank G. Shellock, Ph. D. Request for permission to reproduce any information contained on the MRISAFETY.COM web site should be addressed to: frank.shellock@gte.net
Be sure to read our Disclaimer.