radioactive tracers bound to carrier molecules. IV injection, inhalation, swallow, or IM injection.

SPECT imagers detect gamma ray emissions from radiotracers.

Usages: Many things. Some egs: heart disease(myocardial perfusion scan), bone disorders (bone scan), kidneys (renal DMSA/MAG-3 scan), Thyroid scintigraphy, V/Q scans, Hepatobiliary scans (HIDA/DIDA), Neuroimaging (Brain perfusion)

PET scans measure photons produced during the decay of radiotracers. Mainly used to detect/monitor cancer.

Pros: functional, can do selective imaging, can be used for treatment

Cons: access, radiation, expensive, IV access