Tuberculum sellae - occipital protuberance line

Dr Francis Fortin and Andrew Murphy et al.

The tuberculum sellae-occipital protuberance line (TS-OP line), is an imaging reference line that runs almost parallel to the anterior commissure-posterior commissure line (AC-PC line) 1.
It is a practical reference line for reformatting or tilting of the gantry during CT acquisition of the head to better align with axial MRI reformats of the brain. 

CT reformats of the brain have traditionally been conducted in reference to the orbitomeatal line (OML). However, there are inconsistencies between the OML and the AC-PC line 2. The AC-PC line is widely accepted by the neuroimaging community as the standard reference plane for axial imaging 3, yet it is not always possible to visualise the anterior and posterior commissures on a CT acquisition. 

Using midsagittal images (or the scout), draw a line from the tuberculum sellae to the internal occipital protuberance or the external occipital protuberance. Using this reference line will result in axial reformats that run almost parallel to the AC-PC line 1. Utilising the TS-OP line allows for a greater comparability between examinations and assists the radiologist when comparing to MRI examinations.

CT examinations
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Article information

rID: 63430
Synonyms or Alternate Spellings:
  • TS-OP line

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Cases and figures

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    Figure 1: TS-OP line (diagram)
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