Positron Emission Tomography (PET)

Positron Emission Tomography is a functional imaging technique that uses radioactive substances known as radiotracers to visualize and measure changes in metabolic processes, and in other physiological activities including blood flow, regional chemical composition, and absorption. They use different tracers for different imaging, depending on the target process within the body. We inject a radiopharmaceutical—a radioisotope attached to a drug—into the body as a tracer. Gamma cameras emit and detect Gamma rays to form a three-dimensional image, similar to that of an X-ray image. Positron-emission tomography scanners can incorporate a computerized tomography scanner, and we call them positron-emission tomography-computerized tomography scanners. One disadvantage of a positron-emission tomography scanner is its high initial cost and ongoing operating costs.

Applications

Positron-emission tomography can give information about:

1. Metabolic changes
2. Regional cerebral blood flow
3. Ligand binding

Clinical Uses 

We can use positron-emission tomography in the assessment of several neurological conditions. It is especially helpful for differentiating dementia of Alzheimer's type from frontotemporal dementias. 

1. Cerebrovascular disease
2. Alzheimer’s disease
3. Epilepsy, prior to neurosurgery
4. Head injury

Panic Disorder

Studies have shown decreased activity in the right parahippocampal region.

Obsessive-compulsive Disorder

Hypermetabolism in the orbitofrontal cortex and caudate nucleus; normalizes with treatment

1. Bailey DL, Townsend DW, Valk PE, Maisy MN (2005). Positron Emission Tomography: Basic Sciences. Secaucus, NJ: Springer-Verlag. ISBN 978-1-85233-798-8.
2. Carlson N (January 22, 2012). Physiology of Behavior. Methods and Strategies of Research. 11th edition. Pearson. p. 151. ISBN 978-0205239399."