Which statement is true about PET imaging?

• A. It provides only structural anatomy.
• B. It detects biochemical and metabolic changes using positron decay.
• C. It cannot be used for oncology.
• D. It is inherently a two-dimensional modality.

Answer: (B)

PET imaging focuses on measuring metabolic and biochemical activity in tissues using radiotracers that emit positrons. When these positrons encounter electrons, they annihilate and produce two gamma photons that the detectors capture, allowing a map of tracer uptake to be built. This makes PET a functional imaging modality, revealing metabolic changes that often precede visible structural damage. A common tracer like FDG highlights areas with increased glucose metabolism, which is a hallmark of many cancers, explaining why PET is so useful in oncology for detecting tumors, staging disease, and monitoring treatment response. PET is frequently combined with CT or MRI to add anatomical context, forming PET/CT or PET/MRI studies. It is not confined to two-dimensional views; the data are reconstructed in three dimensions to show the distribution of activity throughout the volume.