SPECT (single-photon emission computed tomography) is a nuclear medicine scan that builds 3D images of how an organ is working, by having the gamma camera rotate around you rather than taking flat pictures. It's often combined with a CT in the same machine — 'SPECT-CT' — which adds detailed anatomy, so doctors can pinpoint exactly where a functional finding is. It uses the same small tracers as other nuclear medicine and is painless.
Key takeaways
- SPECT creates 3D images of how an organ is functioning.
- The gamma camera rotates around you to capture the 3D information.
- SPECT-CT combines this with a CT for precise anatomy.
- It uses the same small tracers as other nuclear medicine; it's painless.
SPECT stands for single-photon emission computed tomography. It’s a form of nuclear medicine that, instead of flat pictures, builds 3D images of how an organ or area is working.[1]
How it’s different
A standard nuclear medicine scan often produces flat (2D) images from a gamma camera. In SPECT, the gamma camera heads rotate around your body, capturing the tracer’s signal from many angles, which a computer reconstructs into a 3D picture.[1] This can localise a finding far more precisely than a flat image.
SPECT-CT: function plus anatomy
SPECT is increasingly combined with a CT scan in the same machine, called SPECT-CT.[1] The SPECT shows the function (where the tracer collects) and the CT adds detailed anatomy — so doctors can pinpoint exactly where a functional finding is, such as the precise bone or structure involved. Combining the two (“image fusion”) leads to more precise information and a more confident diagnosis.[1]
What to expect
A SPECT scan uses the same small radioactive tracers as other nuclear medicine, given by injection.[1] During imaging, the camera rotates slowly around you while you lie still — it’s painless, though staying still for a while can be the main challenge. Where a CT is added, it contributes a small extra radiation dose, balanced against the more precise information it provides.[2]
Frequently asked questions
What’s the difference between SPECT and a standard nuclear medicine scan?
A standard scan often gives flat 2D pictures; SPECT builds 3D images by rotating the camera around you, which localises findings more precisely — especially when combined with CT as SPECT-CT.[1]
Why add a CT to a SPECT scan?
The CT provides detailed anatomy, so the functional SPECT finding can be matched to an exact location in the body — improving accuracy.[1]
Is SPECT safe?
Yes — it uses the same small tracer dose as other nuclear medicine, with the same excellent safety record. Any added CT contributes a small extra dose, weighed against the benefit.[2]
Sources
- RadiologyInfo.org (RSNA & ACR) — General Nuclear Medicine — www.radiologyinfo.org/en/info/gennuclear
- RANZCR / InsideRadiology — Nuclear medicine (Cain) — www.insideradiology.com.au/nuclear-medicine/
