Positron emission tomography (PET) uses radioisotope-labeled tracers that are injected into or ingested by the subject. The radiation is measured and can be imaged in 3-D.
microPET is a specialized version of PET that creates the high-resolution images necessary to image small animals. This imaging technique is similar to SPECT in that it monitors the distribution of treatments and probes as they circulate through a living body. Treatments can be labeled with radioactive particles, which broadcast their location to the PET machine while inside the body. This capability allows experiments to be designed so the same animals can be used throughout the experiment, which reduces the burden on the animals and decreases uncertainty in the results.
The differences between PET and SPECT lie in the properties of the radioactive particles, which produce the radiation that creates the image. SPECT uses radiotracers that undergo gamma decay and give off photons that are measured by a gamma camera. PET uses radiotracers that undergo a special form of beta decay called positron emission. These positrons travel a short distance through the subject until they encounter an electron, which causes mutual annihilation. This annihilation reaction produces a pair of photons that travel in opposite directions and can be measured with a gamma camera.
Specific applications include:
Sofie GENISYS 4
Resolution: ~1 mm