Positron emission tomography (PET) 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. Different tracers are used for various imaging purposes, depending on the target process within the body.
Fluorine-18 (18F) is a fluorine radioisotope which is an important source of positrons. It has a mass of 18.0009380(6) u and its half-life is 109.771(20) minutes. It decays by positron emission 96.7% of the time and electron capture 3.3% of the time. Both modes of decay yield stable oxygen-18.
In pharmacokinetics and receptor-ligand kinetics the binding potential (BP) is a combined measure of the density of "available" neuroreceptors and the affinity of a drug to that neuroreceptor.
Cannabinoid receptor 1 (CB1), is a G protein-coupled cannabinoid receptor that in humans is encoded by the CNR1 gene. The human CB1 receptor is expressed in the peripheral nervous system and central nervous system. It is activated by endogenous cannabinoids called endocannabinoids, a group of retrograde neurotransmitters that include lipids, such as anandamide and 2-arachidonoylglycerol (2-AG); plant phytocannabinoids, such as docosatetraenoylethanolamide found in wild daga, the compound THC which is an active constituent of the psychoactive drug cannabis; and synthetic analogs of THC. CB1 is antagonized by the phytocannabinoid tetrahydrocannabivarin (THCV).
Altanserin is a compound that binds to the 5-HT2A receptor. Labeled with the isotope fluorine-18 it is used as a radioligand in positron emission tomography (PET) studies of the brain, i.e., studies of the 5-HT2A neuroreceptors. Besides human neuroimaging studies altanserin has also been used in the study of rats.
Emission computed tomography (ECT) is a type of tomography involving radioactive or emissions. Types include positron emission tomography (PET) and Single-photon emission computed tomography (SPECT).
AM-1220 is a drug that acts as a potent and moderately selective agonist for the cannabinoid receptor CB1, with around 19 times selectivity for CB1 over the related CB2 receptor. It was originally invented in the early 1990s by a team led by Thomas D'Ambra at Sterling Winthrop, but has subsequently been researched by many others, most notably the team led by Alexandros Makriyannis at the University of Connecticut. The (piperidin-2-yl)methyl side chain of AM-1220 contains a stereocenter, so there are two enantiomers with quite different potency, the (R)-enantiomer having a Ki of 0.27 nM at CB1 while the (S)-enantiomer has a much weaker Ki of 217 nM.
Brain positron emission tomography is a form of positron emission tomography (PET) that is used to measure brain metabolism and the distribution of exogenous radiolabeled chemical agents throughout the brain. PET measures emissions from radioactively labeled metabolically active chemicals that have been injected into the bloodstream. The emission data from brain PET are computer-processed to produce multi-dimensional images of the distribution of the chemicals throughout the brain.
Mefway is a serotonin 5-HT1A receptor antagonist used in medical research, usually in the form of mefway (18F) as a positron emission tomography (PET) radiotracer.
Iomazenil is an antagonist and partial inverse agonist of benzodiazepine and a potential treatment for alcohol use disorder. The compound was introduced in 1989 by pharmaceutical company Hoffmann-La Roche as an Iodine-123-labelled SPECT tracer for imaging benzodiazepine receptors in the brain. Iomazenil is an analogue of flumazenil (Ro15-1788).
PipISB is a drug used in scientific research which acts as a potent and selective inverse agonist of the cannabinoid receptor CB1. It is highly selective for the CB1 receptor over CB2, with a Kd at CB1 of 1.5nM vs over 7000nM at CB2, has good blood–brain barrier penetration, and can be conveniently radiolabelled with either 11C or 18F, making it useful for mapping the distribution of CB1 receptors in the brain.
Radiofluorination is the process by which a radioactive isotope of fluorine is attached to a molecule and is preferably performed by nucleophilic substitution using nitro or halogens as leaving groups. Fluorine-18 is the most common isotope used for this procedure. This is due to its 97% positron emission and relatively long 109.8 min half-life. The half-life allows for a long enough time to be incorporated into the molecule and be used without causing exceedingly harmful effects. This process has many applications especially with the use of positron emission tomography (PET) as the aforementioned low positron energy is able to yield a high resolution in PET imaging.
Fallypride is a high affinity dopamine D2/D3 receptor antagonist used in medical research, usually in the form of fallypride (18F) as a positron emission tomography (PET) radiotracer in human studies.
Desmethoxyfallypride is a moderate affinity dopamine D2 receptor/D3 receptor antagonist used in medical research, usually in the form of the radiopharmaceutical [F-18]-desmethoxyfallypride (DMFP(18F)) which has been used in human studies as a positron emission tomography (PET) radiotracer.
PET radiotracer is a type of radioligand that is used for the diagnostic purposes via positron emission tomography imaging technique.
Fluciclovine (18F), also known as anti-1-amino-3-18F-fluorocyclobutane-1-carboxylic acid, and sold under the brand name Axumin, is a diagnostic agent used for positron emission tomography (PET) imaging in men with suspected prostate cancer recurrence based on elevated prostate specific antigen (PSA) levels.
Arterial input function (AIF), also known as a plasma input function, refers to the concentration of tracer in blood-plasma in an artery measured over time. The oldest record on PubMed shows that AIF was used by Harvey et al. in 1962 to measure the exchange of materials between red blood cells and blood plasma, and by other researchers in 1983 for positron emission tomography (PET) studies. Nowadays, kinetic analysis is performed in various medical imaging techniques, which requires an AIF as one of the inputs to the mathematical model, for example, in dynamic PET imaging, or perfusion CT, or dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).
Positron emission tomography for bone imaging, as an in vivo tracer technique, allows the measurement of the regional concentration of radioactivity proportional to the image pixel values averaged over a region of interest (ROI) in bones. Positron emission tomography is a functional imaging technique that uses [18F]NaF radiotracer to visualise and quantify regional bone metabolism and blood flow. [18F]NaF has been used for imaging bones for the last 60 years. This article focuses on the pharmacokinetics of [18F]NaF in bones, and various semi-quantitative and quantitative methods for quantifying regional bone metabolism using [18F]NaF PET images.
Fluoroestradiol F-18, also known as [18F]16α-fluoroestradiol and sold under the brand name Cerianna, is a radioactive diagnostic agent indicated for use with positron emission tomography (PET) imaging. It is an analog of estrogen and is used to detect estrogen receptor-positive breast cancer lesions.
Julie C. Price is an American medical physicist and professor of radiology at Massachusetts General Hospital (MGH), Harvard Medical School (HMS), as well as the director of PET Pharmacokinetic Modeling at the Athinoula A. Martinos Center at MGH. Price is a leader in the study and application of quantitative positron emission tomography (PET) methods. Prior to this, Price worked with Pittsburgh colleagues to lead the first fully quantitative pharmacokinetic evaluations of 11C-labeled Pittsburgh compound-B (PIB), one of the most widely used PET ligands for imaging amyloid beta plaques. As a principal investigator at MGH, Price continues work to validate novel PET methods for imaging biological markers of health and disease in studies of aging and neurodegeneration, including studies of glucose metabolism, protein expression, neurotransmitter system function, and tau and amyloid beta plaque burden.
