Shading artifact

Last revised by Frank Gaillard on 28 May 2023

Shading artifact is an MRI artifacts and refers to loss of signal intensity in one part of the image, leading to dark shading in this portion of the image.

Causes
  • uneven excitation of nuclei within the field; due to RF pulses applied at flip angles other than 90 and 180 degrees

  • abnormal loading of coil or coupling of the coil at a point (as with a large patient who touches one side of the coil)

  • inhomogeneity in the magnetic field

  • overflow of analog to digital converter

Axis
  • frequency encoding

  • phase encoding

Remedy

  • load the coil correctly

  • use the proper size coil for patient size and the examined part

  • prevent the patient from touching the coil (you can use foam pads between the patient and the coil)

  • shimming to reduce the inhomogeneity of the magnetic field

  • use the proper scanning parameters to set proper amplitude of applied RF pulses (less amplification to avoid analog to digital converter over flow)

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