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Metal Artifact, Craniovertebral Junction
Lubdha M. Shah, MD
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KEY FACTS

  • Terminology

    • Imaging

      TERMINOLOGY

      • Synonyms

        • CT: Beam-hardening artifact, streak artifact, and blooming artifact
        • MR: Magnetic susceptibility artifact
      • Definitions

        • Image degradation related to metal prostheses/implants
        • Magnetic susceptibility
          • Partial magnetization of material in presence of applied external magnetic field
          • Artifact consists of 2 additive components
            • Geometric distortion + signal loss secondary to dephasing
        • Tissues with greatly different magnetic susceptibilities in uniform magnetic field lead to difference of susceptibilities causing inhomogeneities in local magnetic field → altered phase and frequency of local spins
          • Spins mapped to erroneous location within image
            • → distortion of shape along axes of frequency encoding and section selection
            • → loss of signal within the metallic object with rim of high signal intensity
        • Object placed within homogeneous magnet produces inhomogeneities in local magnetic field that interfere with the imaging gradient field
          • Artifacts in patients with metallic implants produced by differences in magnetic properties of the implanted metals and those of human tissues → local magnetic field inhomogeneities, altered phase and frequency of local spins

      IMAGING

      • General Features

        • Radiographic Findings

          • CT Findings

            • MR Findings

              • Nonvascular Interventions

                • Imaging Recommendations

                  DIFFERENTIAL DIAGNOSIS

                    PATHOLOGY

                    • General Features

                      CLINICAL ISSUES

                      • Presentation

                        • Demographics

                          DIAGNOSTIC CHECKLIST

                          • Consider

                            • Image Interpretation Pearls

                              Selected References

                              1. Bamberg F et al: Metal artifact reduction by dual energy computed tomography using monoenergetic extrapolation. Eur Radiol. 21(7):1424-9, 2011
                              2. Buckwalter KA et al: Managing postoperative artifacts on computed tomography and magnetic resonance imaging. Semin Musculoskelet Radiol. 15(4):309-19, 2011
                              3. Zhou C et al: Monoenergetic imaging of dual-energy CT reduces artifacts from implanted metal orthopedic devices in patients with factures. Acad Radiol. 18(10):1252-7, 2011
                              4. Stradiotti P et al: Metal-related artifacts in instrumented spine. Techniques for reducing artifacts in CT and MRI: state of the art. Eur Spine J. 18 Suppl 1:102-8, 2009
                              5. Lee MJ et al: Overcoming artifacts from metallic orthopedic implants at high-field-strength MR imaging and multi-detector CT. Radiographics. 27(3):791-803, 2007
                              6. Buckwalter KA et al: Multichannel CT imaging of orthopedic hardware and implants. Semin Musculoskelet Radiol. 10(1):86-97, 2006
                              7. Chang SD et al: MRI of spinal hardware: comparison of conventional T1-weighted sequence with a new metal artifact reduction sequence. Skeletal Radiol. 30(4):213-8, 2001
                              8. Viano AM et al: Improved MR imaging for patients with metallic implants. Magn Reson Imaging. 18(3):287-95, 2000
                              9. Henk CB et al: The postoperative spine. Top Magn Reson Imaging. 10(4):247-64, 1999
                              10. Rudisch A et al: Metallic artifacts in magnetic resonance imaging of patients with spinal fusion. A comparison of implant materials and imaging sequences. Spine. 23(6):692-9, 1998
                              11. Suh JS et al: Minimizing artifacts caused by metallic implants at MR imaging: experimental and clinical studies. AJR Am J Roentgenol. 171(5):1207-13, 1998
                              12. Taber KH et al: Pitfalls and artifacts encountered in clinical MR imaging of the spine. Radiographics. 18(6):1499-521, 1998
                              13. Wang JC et al: A comparison of magnetic resonance and computed tomographic image quality after the implantation of tantalum and titanium spinal instrumentation. Spine. 23(15):1684-8, 1998
                              14. Frazzini VI et al: Internally stabilized spine: optimal choice of frequency-encoding gradient direction during MR imaging minimizes susceptibility artifact from titanium vertebral body screws. Radiology. 204(1):268-72, 1997
                              15. Doran SE et al: Internal fixation of the spine using a braided titanium cable: clinical results and postoperative magnetic resonance imaging. Neurosurgery. 38(3):493-6; discussion 496-7, 1996
                              16. Ortiz O et al: Postoperative magnetic resonance imaging with titanium implants of the thoracic and lumbar spine. Neurosurgery. 38(4):741-5, 1996
                              17. Petersilge CA et al: Optimizing imaging parameters for MR evaluation of the spine with titanium pedicle screws. AJR Am J Roentgenol. 166(5):1213-8, 1996
                              18. Shellock FG: MR imaging and cervical fixation devices: evaluation of ferromagnetism, heating, and artifacts at 1.5 Tesla. Magn Reson Imaging. 14(9):1093-8, 1996
                              19. Tominaga T et al: Magnetic resonance imaging of titanium anterior cervical spine plating systems. Neurosurgery. 36(5):951-5, 1995
                              20. Tartaglino LM et al: Metallic artifacts on MR images of the postoperative spine: reduction with fast spin-echo techniques. Radiology. 190(2):565-9, 1994
                              21. Vaccaro AR et al: Metallic spinal artifacts in magnetic resonance imaging. Spine. 19(11):1237-42, 1994
                              Related Anatomy
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                              Related Differential Diagnoses
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                              References
                              Tables

                              Tables

                              KEY FACTS

                              • Terminology

                                • Imaging

                                  TERMINOLOGY

                                  • Synonyms

                                    • CT: Beam-hardening artifact, streak artifact, and blooming artifact
                                    • MR: Magnetic susceptibility artifact
                                  • Definitions

                                    • Image degradation related to metal prostheses/implants
                                    • Magnetic susceptibility
                                      • Partial magnetization of material in presence of applied external magnetic field
                                      • Artifact consists of 2 additive components
                                        • Geometric distortion + signal loss secondary to dephasing
                                    • Tissues with greatly different magnetic susceptibilities in uniform magnetic field lead to difference of susceptibilities causing inhomogeneities in local magnetic field → altered phase and frequency of local spins
                                      • Spins mapped to erroneous location within image
                                        • → distortion of shape along axes of frequency encoding and section selection
                                        • → loss of signal within the metallic object with rim of high signal intensity
                                    • Object placed within homogeneous magnet produces inhomogeneities in local magnetic field that interfere with the imaging gradient field
                                      • Artifacts in patients with metallic implants produced by differences in magnetic properties of the implanted metals and those of human tissues → local magnetic field inhomogeneities, altered phase and frequency of local spins

                                  IMAGING

                                  • General Features

                                    • Radiographic Findings

                                      • CT Findings

                                        • MR Findings

                                          • Nonvascular Interventions

                                            • Imaging Recommendations

                                              DIFFERENTIAL DIAGNOSIS

                                                PATHOLOGY

                                                • General Features

                                                  CLINICAL ISSUES

                                                  • Presentation

                                                    • Demographics

                                                      DIAGNOSTIC CHECKLIST

                                                      • Consider

                                                        • Image Interpretation Pearls

                                                          Selected References

                                                          1. Bamberg F et al: Metal artifact reduction by dual energy computed tomography using monoenergetic extrapolation. Eur Radiol. 21(7):1424-9, 2011
                                                          2. Buckwalter KA et al: Managing postoperative artifacts on computed tomography and magnetic resonance imaging. Semin Musculoskelet Radiol. 15(4):309-19, 2011
                                                          3. Zhou C et al: Monoenergetic imaging of dual-energy CT reduces artifacts from implanted metal orthopedic devices in patients with factures. Acad Radiol. 18(10):1252-7, 2011
                                                          4. Stradiotti P et al: Metal-related artifacts in instrumented spine. Techniques for reducing artifacts in CT and MRI: state of the art. Eur Spine J. 18 Suppl 1:102-8, 2009
                                                          5. Lee MJ et al: Overcoming artifacts from metallic orthopedic implants at high-field-strength MR imaging and multi-detector CT. Radiographics. 27(3):791-803, 2007
                                                          6. Buckwalter KA et al: Multichannel CT imaging of orthopedic hardware and implants. Semin Musculoskelet Radiol. 10(1):86-97, 2006
                                                          7. Chang SD et al: MRI of spinal hardware: comparison of conventional T1-weighted sequence with a new metal artifact reduction sequence. Skeletal Radiol. 30(4):213-8, 2001
                                                          8. Viano AM et al: Improved MR imaging for patients with metallic implants. Magn Reson Imaging. 18(3):287-95, 2000
                                                          9. Henk CB et al: The postoperative spine. Top Magn Reson Imaging. 10(4):247-64, 1999
                                                          10. Rudisch A et al: Metallic artifacts in magnetic resonance imaging of patients with spinal fusion. A comparison of implant materials and imaging sequences. Spine. 23(6):692-9, 1998
                                                          11. Suh JS et al: Minimizing artifacts caused by metallic implants at MR imaging: experimental and clinical studies. AJR Am J Roentgenol. 171(5):1207-13, 1998
                                                          12. Taber KH et al: Pitfalls and artifacts encountered in clinical MR imaging of the spine. Radiographics. 18(6):1499-521, 1998
                                                          13. Wang JC et al: A comparison of magnetic resonance and computed tomographic image quality after the implantation of tantalum and titanium spinal instrumentation. Spine. 23(15):1684-8, 1998
                                                          14. Frazzini VI et al: Internally stabilized spine: optimal choice of frequency-encoding gradient direction during MR imaging minimizes susceptibility artifact from titanium vertebral body screws. Radiology. 204(1):268-72, 1997
                                                          15. Doran SE et al: Internal fixation of the spine using a braided titanium cable: clinical results and postoperative magnetic resonance imaging. Neurosurgery. 38(3):493-6; discussion 496-7, 1996
                                                          16. Ortiz O et al: Postoperative magnetic resonance imaging with titanium implants of the thoracic and lumbar spine. Neurosurgery. 38(4):741-5, 1996
                                                          17. Petersilge CA et al: Optimizing imaging parameters for MR evaluation of the spine with titanium pedicle screws. AJR Am J Roentgenol. 166(5):1213-8, 1996
                                                          18. Shellock FG: MR imaging and cervical fixation devices: evaluation of ferromagnetism, heating, and artifacts at 1.5 Tesla. Magn Reson Imaging. 14(9):1093-8, 1996
                                                          19. Tominaga T et al: Magnetic resonance imaging of titanium anterior cervical spine plating systems. Neurosurgery. 36(5):951-5, 1995
                                                          20. Tartaglino LM et al: Metallic artifacts on MR images of the postoperative spine: reduction with fast spin-echo techniques. Radiology. 190(2):565-9, 1994
                                                          21. Vaccaro AR et al: Metallic spinal artifacts in magnetic resonance imaging. Spine. 19(11):1237-42, 1994