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Physics and Safety

Part of the Contemporary Cardiology book series (CONCARD)
  1. 1.
    The magnetic field strength (1.5 T) routinely used for cardiovascular magnetic resonance imaging (CMR) is:
    1. A.

      Roughly equal to the earth's magnetic field

       
    2. B.

      One hundred times stronger than the earth's magnetic field

       
    3. C.

      One thousand times stronger than the earth's magnetic field

       
    4. D.

      Thirty thousand times stronger than the earth's magnetic field

       
    5. E.

      One hundred and twenty thousand times stronger than the earth's magnetic field

       

    Correct answer is D.

    The strength of a magnetic field may be measured in tesla (T) or gauss. One tesla is equal to 10,000 gauss. The earth's magnetic field at the earth's surface varies between 0.3 and 0.6 gauss. Most clinical CMR scanners use a magnetic field of 1.5 T, or 15,000 gauss, i.e., approximately 30,000 times stronger than the earth's magnetic field. [1, 2]

     
  2. 2.
    For magnetic resonance imaging (MRI), the signal that is used to create the image is emitted from:
    1. A.

      The carbon-12 nuclei (C12)

       
    2. B.

      The oxygen-16 nuclei (O16)

       
    3. C.

      The nitrogen-14...

Keywords

Cardiovascular Magnetic Resonance Correct Answer Magnetic Field Strength Implantable Cardiac Defibrillator Inversion Recovery Sequence 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

References

  1. 1.
    National Geophysical Data Center (NGDC). Earth's magnetic field calculators. http://www.ngdc.noaa.gov/seg/geomag/magfield.shtml.
  2. 2.
    2. van Geuns RJ, Wielopolski PA, de Bruin HG, et al. Basic principles of magnetic resonance imaging. Prog Cardiovasc Dis, 1999;42(2):149–156.CrossRefPubMedGoogle Scholar
  3. 3.
    National Inqtitute of Standards and Technolegy (NIST) NIfSaT. http://physics.nist.gmv/.
  4. 4.
    4. Edelman RR and Warach S. Magnetic resonance imaging (1). N Engl J Med, 1993;328(10):708–716.CrossRefPubMedGoogle Scholar
  5. 5.
    5. Longmore DB. The principles of magnetic resonance. Br Med Bull, 1989;45(4):848–880.PubMedGoogle Scholar
  6. 6.
    6. Schenck JF. Physical interactions of static magnetic fields with living tissues. Prog Biophys Mol Biol, 2005;87(2-3):185–204.CrossRefPubMedGoogle Scholar
  7. 7.
    7. Bottomley PA, Foster TH, Argersinger RE, and Pfeifer LM. A review of normal tissue hydrogen NMR relaxation times and relaxation mechanisms from 1–100 MHz: dependence on tissue type, NMR frequency, temperature, species, excision, and age. Med Phys, 1984;11(4):425–448.CrossRefPubMedGoogle Scholar
  8. 8.
    8. Gold GE, Han E, Stainsby J, Wright G, Brittain J, and Beaulieu C. Musculoskeletal MRI at 3.0 T: relaxation times and image contrast. AJR Am J Roentgenol, 2004;183(2):343–351.PubMedGoogle Scholar
  9. 9.
    9. Roussakis A, Baras P, Seimenis I, Andreou J, and Danias PG. Relationship of number of phases per cardiac cycle and accuracy of measurement of left ventricular volumes, ejection fraction, and mass. J Cardiovasc Magn Reson, 2004;6(4):837–844.CrossRefPubMedGoogle Scholar
  10. 10.
    10. Fischer SE, Wickline SA, and Lorenz CH. Novel real-time R-wave detection algorithm based on the vectorcardiogram for accurate gated magnetic resonance acquisitions. Magn Reson Med, 1999;42(2):361–370.CrossRefPubMedGoogle Scholar
  11. 11.
    11. Haacke EM, Li D, and Kaushikkar S. Cardiac MR imaging: principles and techniques. Top Magn Reson Imaging, 1995;7(4):200–217.CrossRefPubMedGoogle Scholar
  12. 12.
    U.S. Department Of Health and Human Services FDA, Center for Devices and Radiological Health (CDRH). Guidance for the submission of premarket notifications for magnetic resonance diagnostic devices. http://www.fda.gov/cdrh/ode/mri340.pdf. 1998.
  13. 13.
    C95.1 ANSI/IEEE. IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz,” ANSI/IEEE C95.1-1992 (Revision of ANSI C95.1-1982), Institute of Electrical and Electronics Engineers, Inc., Piscataway, NJ. 1992.Google Scholar
  14. 14.
    14. Schaefer DJ, Bourland JD, and Nyenhuis JA. Review of patient safety in time-varying gradient fields. J Magn Reson Imaging, 2000;12(1):20–29.CrossRefPubMedGoogle Scholar
  15. 15.
    U.S. Department Of Health and Human Services FDA, Center for Devices and Radiological Health (CDRH). Guidance for industry and FDA staff. Criteria for significant risk investigations of magnetic resonance diagnostic devices. http://www.fda.gov/cdrh/ode/guidance/793.pdf. 2003.
  16. 16.
    16. Schenck JF. Safety of strong, static magnetic fields. J Magn Reson Imaging, 2000;12(1): 2–19.CrossRefPubMedGoogle Scholar
  17. 17.
    17. Barnhart JL and Berk RN. Influence of paramagnetic ions and pH on proton NMR relaxation of biologic fluids. Invest Radiol, 1986;21(2):132–136.CrossRefPubMedGoogle Scholar
  18. 18.
    18. Strich G, Hagan PL, Gerber KH, and Slutsky RA. Tissue distribution and magnetic resonance spin lattice relaxation effects of gadolinium-DTPA. Radiology, 1985;154(3):723–726.PubMedGoogle Scholar
  19. 19.
    19. Strijkers GJ, Mulder WJ, van Tilborg GA, and Nicolay K. MRI contrast agents: current status and future perspectives. Anticancer Agents Med Chem, 2007;7(3):291–305.CrossRefPubMedGoogle Scholar
  20. 20.
    20. Kirchin MA and Runge VM. Contrast agents for magnetic resonance imaging: safety update. Top Magn Reson Imaging, 2003;14(5):426–435.CrossRefPubMedGoogle Scholar
  21. 21.
    21. Li A, Wong CS, Wong MK, Lee CM, and Au Yeung MC. Acute adverse reactions to magnetic resonance contrast media—gadolinium chelates. Br J Radiol, 2006;79(941):368–371.CrossRefPubMedGoogle Scholar
  22. 22.
    22. Caro JJ, Trindade E, and McGregor M. The risks of death and of severe nonfatal reactions with high- vs low-osmolality contrast media: a meta-analysis. AJR Am J Roentgenol, 1991;156(4):825–832.PubMedGoogle Scholar
  23. 23.
    23. Grobner T and Prischl FC. Gadolinium and nephrogenic systemic fibrosis. Kidney Int, 2007;72(3):260–264.CrossRefPubMedGoogle Scholar
  24. 24.
    24. Broome DR, Girguis MS, Baron PW, Cottrell AC, Kjellin I, and Kirk GA. Gadodiamide-associated nephrogenic systemic fibrosis: why radiologists should be concerned. AJR Am J Roentgenol, 2007;188(2):586–592.CrossRefPubMedGoogle Scholar
  25. 25.
    25. Karlik SJ. Gadodiamide-associated nephrogenic systemic fibrosis. AJR Am J Roentgenol, 2007;188(6):W584; author reply W585.CrossRefPubMedGoogle Scholar
  26. 26.
    26. Sadowski EA, Bennett LK, Chan MR, et al. Nephrogenic systemic fibrosis: risk factors and incidence estimation. Radiology, 2007;243(1):148–157.CrossRefPubMedGoogle Scholar
  27. 27.
    27. Roguin A, Zviman MM, Meininger GR, et al. Modern pacemaker and implantable cardioverter/defibrillator systems can be magnetic resonance imaging safe: in vitro and in vivo assessment of safety and function at 1.5 T. Circulation, 2004;110(5):475–482.CrossRefPubMedGoogle Scholar
  28. 28.
    28. Shellock FG, Fischer L, and Fieno DS. Cardiac pacemakers and implantable cardioverter defibrillators: in vitro magnetic resonance imaging evaluation at 1.5-tesla. J Cardiovasc Magn Reson, 2007;9(1):21–31.CrossRefPubMedGoogle Scholar
  29. 29.
    29. Martin ET, Coman JA, Shellock FG, Pulling CC, Fair R, and Jenkins K. Magnetic resonance imaging and cardiac pacemaker safety at 1.5-Tesla. J Am Coll Cardiol, 2004;43(7): 1315–1324.CrossRefPubMedGoogle Scholar
  30. 30.
    30. Shellock FG, Tkach JA, Ruggieri PM, Masaryk TJ, and Rasmussen PA. Aneurysm clips: evaluation of magnetic field interactions and translational attraction by use of “long-bore” and “short-bore” 3.0-T MR imaging systems. AJNR Am J Neuroradiol, 2003;24(3):463–471.PubMedGoogle Scholar
  31. 31.
    31. Shellock FG. Magnetic resonance safety update 2002: implants and devices. J Magn Reson Imaging, 2002;16(5):485–496.CrossRefPubMedGoogle Scholar
  32. 32.
    32. Edwards MB, Ordidge RJ, Hand JW, Taylor KM, and Young IR. Assessment of magnetic field (4.7 T) induced forces on prosthetic heart valves and annuloplasty rings. J Magn Reson Imaging, 2005;22(2):311–317.CrossRefPubMedGoogle Scholar
  33. 33.
    33. Shinbane JS, Colletti PM, and Shellock FG. MR in patients with pacemakers and ICDs: Defining the issues. J Cardiovasc Magn Reson, 2007;9(1):5–13.CrossRefPubMedGoogle Scholar
  34. 34.
    34. Boutin RD, Briggs JE, and Williamson MR. Injuries associated with MR imaging: survey of safety records and methods used to screen patients for metallic foreign bodies before imaging. AJR Am J Roentgenol, 1994;162(1):189–194.PubMedGoogle Scholar

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© Humana Press, a part of Springer Science + Business Media, LLC 2008

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