MRI Artifacts

  1. Gibbs truncation
    bright or dark lines parallel and adjacent to borders of distinct intensity change

    seen when a small matrix is used
  2. Correcting Gibbs truncation artifact
    • Increase number of phase encodings 
    • Reduce FOV
  3. Partial Volume averaging artifact
    occur when multiple tissue types are contained within a single voxel

    occur in slice select direction
  4. Correcting partial voluming artifact
    select thinner slice thickness
  5. Cross talk artifact
    occurs when slices overlap or are too close together

    band of signal loss usually posteriorly and working its way anterior towards the spine in axial acquisitions
  6. Correct Cross talk artifact
    Increase gaps between the slices
  7. Cross excitation artifacts
    signal loss due to partial saturation in adjacent slices

    occurs primarily in STIR imaging
  8. Correcting excitation artifacts
    selecting an interleaved method of slice acquisition to reduce the saturation of adjacent slices
  9. Metal Artifact Reduction
    • Use FSE
    • DO NOT USE Parallel imaging techniques
    • Use Long ETL 
    • Use wide receiver bandwidth 
    • Use Thin Slices
    • Use STIR sequences
    • Increasing NEX
    • Small pixels/large matrix
  10. Moire Fringe artifact
    caused by interference of aliased signals at different phases 

    Zebra artifact

    seen in 3D gradient echo images at higher field strength, when larger FOV is utilized
  11. FID artifacts
    fine line artifacts similar to Gibbs

    originate from an incompletely crushed FID signal from an RF refocusing pulse

    common in FSE sequences
  12. Correcting FID artifacts
    Increasing NEX and/or enabling of Flow Compensation
  13. Magic angle artifact
    occurs when a tendon or ligament is positioned 55* to the direction of the main magnetic field and short TE is used
  14. Annefact Artifact
    • cusp artifact 
    • stems from active RF coil channels or elements outside the scanning FOV
    • typically in spine imaging
  15. Correcting annefact artifact
    De-selecting the elements outside the scanning range
Card Set
MRI Artifacts
MRI artifacts and their corrections