• Motion is the most common  caused by
    • patient,
    • cardiac, or
    • respiratory motion.
  • Attempt at solutions
    • Cardiac motion artifacts
    • Cardiac motion artifacts. (a) Axial CT image shows blurring  and winged appearance of the right coronary artery (arrow).
      Kalisz K et al  Artifacts at Cardiac CT: Physics and Solutions  RadioGraphicsVol. 36, No. 7

      web-CT-011.webp

      Axial CT images obtained at different phases of the cardiac cycle (from 0% to 80% R-R interval) show that the right coronary artery has varying degrees of motion in each of the cardiac phases. In this patient, the motion is least in the 50% and 80% phases of the R-R interval.
      Kalisz K et al  Artifacts at Cardiac CT: Physics and Solutions  RadioGraphicsVol. 36, No. 7

    • can be reduced by
      • decreasing the heart rate and variability and the
      • duration of data acquisition;
      • adjusting the placement of the data window within a cardiac cycle; (diastole
      • performing single-heartbeat scanning; and
      • using multisegment reconstruction,
      • motion-correction algorithms, and
      • electrocardiographic editing.
    • Respiratory motion artifacts can be minimized with
      • proper breath holding and
      • shortened scan duration.
    • Partial volume averaging is
      • caused by the
        • averaging of attenuation values from all tissue contained within a voxel and
      • reduced by
        • improving the spatial resolution,
        • using a higher x-ray energy, or
        • displaying images with a wider window width.
    • Beam-hardening artifacts are
        • caused by the
          • polyenergetic nature of the x-ray beam and can be
        • reduced by using
          • x-ray filtration,
          • applying higher-energy x-rays,
          • altering patient position,
          • modifying contrast material protocols, and
          • applying certain reconstruction algorithms.
      • Metal artifacts are complex and
        • have multiple causes,
          • including x-ray scatter,
          • underpenetration, motion, and
          • attenuation values that exceed the typical dynamic range of Hounsfield units.
      • Quantum mottle or noise is
        • caused by
          • insufficient penetration of tissue and can be
        • improved by
          • increasing the tube current or peak tube potential,
          • reconstructing thicker sections,
          • increasing the rotation time,
          • using appropriate patient positioning, and
          • applying iterative reconstruction algorithms.

 

Links and References

Kalisz K et al  Artifacts at Cardiac CT: Physics and Solutions  RadioGraphicsVol. 36, No. 7