Topic overview

Start with the big picture

PET detects pairs of 511 keV photons produced after positron emission and annihilation, enabling coincidence-based localization and quantitative assessment. Its short-lived radionuclides support tracers such as ¹⁸F-FDG, used in oncology and other clinical settings, as well as agents for specific tumor types, amyloid imaging, and myocardial perfusion. SPECT detects single γ photons with rotating cameras and uses a broader range of tracers, including ⁹⁹ᵐTc compounds for cerebral perfusion, cardiac imaging, and bone scans. Its isotope supply can be supported by ⁹⁹Mo/⁹⁹ᵐTc generators. PET/CT and SPECT/CT combine functional images with anatomical localization. The deeper lesson compares imaging principles, tracers, indications, and practical strengths and limitations.