• SPECT - tomographic imaging technique using gamma rays
•SPECT imaging is performed by using a gamma camera to acquire multiple 2-D images (also called projections), from multiple angles
•To acquire SPECT images, the gamma camera is rotated around the patient
•Common gamma-emitting tracer used in functional brain imaging is
99mTc-HMPAO (hexamethylpropylene amine oxime) (HMPAO). 99mTc is a metastable nuclear isomer which emits gamma rays which can be detected by a gamma camera.
•SPECT imaging is performed by using a gamma camera to acquire multiple 2-D images (also called projections), from multiple angles
•To acquire SPECT images, the gamma camera is rotated around the patient
•Common gamma-emitting tracer used in functional brain imaging is
99mTc-HMPAO (hexamethylpropylene amine oxime) (HMPAO). 99mTc is a metastable nuclear isomer which emits gamma rays which can be detected by a gamma camera.
•The radioisotopes typically used in SPECT to label tracers:
•iodine-123
•technetium-99m
•xenon-133
•thallium-201
•fluorine-18
These radioactive forms of natural elements will pass safely through the body and be detected by the scanner. Various drugs and other chemicals can be labeled with these isotopes without changing their properties.
gamma ray - Electromagnetic radiation emitted by radioactive decay and having energies in a range from ten thousand (104) to ten million (107) electron volts
The crystal scintillates in response to incident gamma radiation: when a gamma photon knocks an electron loose from an iodine atom in the crystal, a faint flash of light is produced when the electron again again finds a minimal energy state. After the flash of light is produced, it must be detected (see figure above)
SPECT - imaging of the human visual cortex
SPECT - imaging of the human visual cortex
NeuroSPECT HMPAO cortical function during Auditory Hallucinations (left) and control (right).