What is a key difference between SPECT and PET imaging?

The key distinction between SPECT and PET imaging lies in their fundamental detection mechanisms. SPECT, or Single Photon Emission Computed Tomography, operates on the principle of detecting individual gamma photons emitted from radiopharmaceuticals that decay within the body. Each radioactive decay generates a single gamma photon that is detected, allowing for the imaging of function and perfusion in various organs.

In contrast, PET, or Positron Emission Tomography, involves a different process where a positron emitted from a radiotracer interacts with an electron, resulting in annihilation and the production of two gamma photons that travel in opposite directions. PET detects these pairs of photons to generate high-resolution images that reflect metabolic activity.

Understanding this fundamental difference emphasizes the distinct nature of how each modality captures and interprets biological processes. This capability of PET to detect pairs of photons contributes to its high sensitivity and resolution in imaging metabolic processes compared to SPECT.