> For the complete documentation index, see [llms.txt](https://docs.snomed.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.snomed.org/education/snomed-ct-education-editorial-guide/readme/authoring/domain-specific-modeling/procedure/index-1/index/multi-modality-imaging-pet-ct-and-spect-ct.md).

# Multi-modality Imaging: PET, CT and SPECT, CT

<mark style="color:$danger;">**This Editorial Guide is used for Education Purposes Only. It is used in the Authoring Courses and Certifications. It is based on the January 2026 Editorial Guide.**</mark>

There are very few imaging procedures which are truly *multi-modality* procedures. Two procedures are usually conducted in parallel, rather than as one. Positron emission tomography with computed tomography (PET/CT) and Single photon emission computed tomography with computed tomography (SPECT/CT), however, are produced by one piece of equipment, possibly by a single technician, but with multiple imaging energies.

## Positron emission tomography with computed tomography

* FSN: Positron emission tomography with computed tomography of X (procedure)
* PT: PET CT of X
* SYN: Positron emission tomography with computed tomography of X
  * For example,
    * 16554361000119106 | Positron emission tomography with computed tomography of brain (procedure)|
      * FSN: Positron emission tomography with computed tomography of brain (procedure)
      * PT: PET CT of brain
      * SYN: Positron emission tomography with computed tomography of brain

## Single photon emission computed tomography with computed tomography

* FSN: Single photon emission computed tomography with computed tomography of X (procedure)
* PT: Single photon emission computed tomography with computed tomography of X
* SYN: SPECT CT of X
  * For example,
    * 16534151000119105 | Single photon emission computed tomography with computed tomography of liver (procedure)|
      * FSN: Single photon emission computed tomography with computed tomography of liver (procedure)
      * PT: Single photon emission computed tomography with computed tomography of liver
      * SYN: SPECT CT of liver

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