AC-PC line

The anterior commissure - posterior commissure line (AC-PC line), also referred as the bicommissural line, has been adopted as a convenient standard by the neuroimaging community, and in most instances is the reference plane for axial imaging in everyday scanning. The creation of a standard image plane makes easier the comparison among exams. 

It is prescribed on midline sagittal images and is similar to the orbitomeatal line traditionally used on CT, although the AC-PC line is typically ~9 degrees steeper than the orbitomeatal line 2

It is strictly defined by Talairach as a line passing through the superior edge of the anterior commissure (AC) and the inferior edge of the posterior commissure (PC) 1-2

An alternative and less commonly used description of thine proposed by Schaltenbrand draws the line trough the midpoint of both the anterior and posterior commissure, resulting in a slightly shallower angle 1,3

Use for CT of the brain

Prior to widespread volumetric CT brain acquisition which has allowed axial images to be reformatted along the AC-PC line, a number of techniques were developed to approximate the CT gantry tilt such that axial images generated were similar to the AC-PC line. Such methods include: 

  1. tuberculum sellae and the external occipital protuberance line 4
  2. hard palate line + 12 degrees 5

See also

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Article information

rID: 25333
Synonyms or Alternate Spellings:
  • Anterior commissure (AC) - posterior commissure (PC) line
  • Anterior commissure posterior commissure line
  • Anterior commissure to posterior commissure line
  • Bicommissural line

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