Black boundary artifact

Black boundary artifact (also known as India ink artifact, chemical shift artifact of the 2nd kind (or type 2), phase cancellation artifact, or black line artifact) is an artificially-created black line located at fat-water interfaces such as those between muscle and fat. This results in a sharp delineation of the muscle-fat boundary lending the image an appearance as if someone has outlined these interfaces with ink that is sometimes visually appealing but not an anatomical structure.  

This artifact occurs in gradient echo sequences as a result of selecting an echo time (TE) in which the fat and water spins (located in the same pixel at an interface) are out of phase, cancelling each other. At 1.5 T, the 3.5 ppm difference in frequency between water and saturated fat results in cancellation of spins at 4.5 ms multiples, starting at about 2.3 ms; for example at 6.8 ms, 11.3 ms, and 15.9 ms. This artifact does not occur with spin echo sequences as the spins are rephased by the 180o refocusing gradient.

Case 1 is a coronal image through the upper body with an echo time of 7 ms. A black line is seen surrounding the muscles of the shoulder girdle as well as around the liver.


To avoid this artifact:

  • choose TEs close to 4.5 ms, 9 ms, 13.6 ms
  • fat suppression can be used
  • a SE sequence instead of GE will also eliminate the artifact
Physics and Imaging Technology: MRI
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Article information

rID: 21766
Section: Physics
Synonyms or Alternate Spellings:
  • Type two chemical shift artefact
  • Type two chemical shift artifact
  • Type 2 chemical shift artefact
  • Type 2 chemical shift artifact
  • India ink artifact
  • India ink artefact
  • Phase cancellation artefact
  • Black line artefact
  • Chemical shift artefact of the 2nd kind
  • Chemical shift artifact of the 2nd kind
  • Chemical shift artefact of the second kind
  • Chemical shift artifact of the second kind
  • Black line artifact
  • Phase cancellation artifact
  • Black boundary artefact
  • Boundary effect

Cases and figures

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    Figure 1: India ink cartoon of Winston Churchill
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    Case 1: black boundary artifact
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    AML : T1 out of p...
    Case 2: T1 out of phase for India ink artifact
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