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.
The vesicular monoamine transporter (VMAT) is a transport protein integrated into the membranes of synaptic vesicles of presynaptic neurons. It transports monoamine neurotransmitters – such as dopamine, serotonin, norepinephrine, epinephrine, and histamine – into the vesicles, which release the neurotransmitters into synapses as chemical messages to postsynaptic neurons. VMATs utilize a proton gradient generated by V-ATPases in vesicle membranes to power monoamine import.
The norepinephrine transporter (NET), also known as noradrenaline transporter (NAT), is a protein that in humans is encoded by the solute carrier family 6 member 2 (SLC6A2) gene.
A bone scan or bone scintigraphy is a nuclear medicine imaging technique of the bone. It can help diagnose a number of bone conditions, including cancer of the bone or metastasis, location of bone inflammation and fractures, and bone infection (osteomyelitis).
The solute carrier family 18 member 2 (SLC18A2) also known as vesicular monoamine transporter 2 (VMAT2) is a protein that in humans is encoded by the SLC18A2 gene. SLC18A2 is an integral membrane protein that transports monoamines—particularly neurotransmitters such as dopamine, norepinephrine, serotonin, and histamine—from cellular cytosol into synaptic vesicles. In nigrostriatal pathway and mesolimbic pathway dopamine-releasing neurons, SLC18A2 function is also necessary for the vesicular release of the neurotransmitter GABA.
Synaptosomal-Associated Protein, 25kDa (SNAP-25) is a Target Soluble NSF (N-ethylmaleimide-sensitive factor) Attachment Protein Receptor (t-SNARE) protein encoded by the SNAP25 gene found on chromosome 20p12.2 in humans. SNAP-25 is a component of the trans-SNARE complex, which accounts for membrane fusion specificity and directly executes fusion by forming a tight complex that brings the synaptic vesicle and plasma membranes together.
The Vesicular acetylcholine transporter (VAChT) is a neurotransmitter transporter which is responsible for loading acetylcholine (ACh) into secretory organelles in neurons making acetylcholine available for secretion. It is encoded by Solute carrier family 18, member 3 (SLC18A3) gene, located within the first intron of the choline acetyltransferase gene. VAChT is able to transport ACh into vesicles by relying on an exchange between protons (H+) that were previously pumped into the vesicle diffusing out, thus acting as an antiporter. ACh molecules are then carried into the vesicle by the action of exiting protons. Acetylcholine transport utilizes a proton gradient established by a vacuolar ATPase.
Kalirin, also known as Huntingtin-associated protein-interacting protein (HAPIP), protein duo (DUO), or serine/threonine-protein kinase with Dbl- and pleckstrin homology domain, is a protein that in humans is encoded by the KALRN gene. Kalirin was first identified in 1997 as a protein interacting with huntingtin-associated protein 1. Is also known to play an important role in nerve growth and axonal development.
The free fraction is a parameter in pharmacokinetics and receptor-ligand kinetics. One speaks of two different free fractions:
Positron emission tomography–magnetic resonance imaging (PET–MRI) is a hybrid imaging technology that incorporates magnetic resonance imaging (MRI) soft tissue morphological imaging and positron emission tomography (PET) functional imaging.
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.
DPA-713 or N,N-diethyl-2-(4-methoxyphenyl)-5,7-dimethylpyrazolo[1,5-a]pyrimidine-3-acetamide is a selective ligand for the translocator protein (TSPO).
Florbetaben, a fluorine-18 (18F)-labeled stilbene derivative, trade name NeuraCeq, is a diagnostic radiotracer developed for routine clinical application to visualize β-amyloid plaques in the brain. It is indicated for Positron Emission Tomography (PET) imaging of β-amyloid neuritic plaque density in the brains of adult patients with cognitive impairment who are being evaluated for Alzheimer's disease (AD) and other causes of cognitive impairment. β-amyloid is a key neuropathological hallmark of AD, so markers of β-amyloid plaque accumulation in the brain are useful in distinguishing AD from other causes of dementia. The tracer successfully completed a global multicenter phase 0–III development program and obtained approval in Europe, US and South Korea in 2014.
LY-2459989 is a silent antagonist of the κ-opioid receptor (KOR) that has been developed by Eli Lilly as a radiotracer of the aforementioned receptor, labeled either with carbon-11 or fluorine-18. It possesses high affinity for the KOR and is highly selective for it over the μ-opioid receptor and the δ-opioid receptor. LY-2459989 is a fluorine-containing analogue and follow-up compound of LY-2795050, the first KOR-selective antagonist radiotracer. Relative to LY-2795050, LY-2459989 displays 4-fold higher affinity for the KOR and similar selectivity and also possesses greatly improved central nervous system permeation. The drug appears to possess a short duration of action, with only 25% remaining in serum at 30 minutes post-injection in rhesus monkeys, making it an ideal agent for application in biomedical imaging, for instance in positron emission tomography (PET).
Fluciclovine (18F), also known as anti-1-amino-3-18F-fluorocyclobutane-1-carboxylic acid, or as Axumin, is a diagnostic agent indicated for positron emission tomography (PET) imaging in men with suspected prostate cancer recurrence based on elevated prostate specific antigen (PSA) levels.
Carbon-11 choline is the basis of medical imaging technologies. Because of its involvement in biologic processes, choline is related to diseases, leading to the development of medical imaging techniques to monitor its concentration. When radiolabeled with 11CH3, choline is a useful a tracer in PET imaging. Carbon-11 is radioactive with a half-life of 20.38 minutes. By monitoring the gamma radiation resulting from the decay of carbon-11, the uptake, distribution, and retention of carbon-11 choline can be monitored.
Christopher H. van Dyck, is the Founder and Director of the Alzheimer’s Disease Research Unit (ADRU) at Yale University School of Medicine, where he is Professor of Psychiatry, Neurology and Neuroscience. His research uses brain imaging to learn about the progression of pathology in Alzheimer's disease, and to test potential new treatments for this disease.
Neil Vasdev is a Canadian and American radiochemist and expert in nuclear medicine and molecular imaging, particularly in the application of PET. Radiotracers developed by the Vasdev Lab are in preclinical use worldwide, and many have been translated for first-in-human neuroimaging studies. He is the director and chief radiochemist of the Brain Health Imaging Centre and director of the Azrieli Centre for Neuro-Radiochemistry at the Centre for Addiction and Mental Health (CAMH). He is the Tier 1 Canada Research Chair in Radiochemistry and Nuclear Medicine, the endowed Azrieli Chair in Brain and Behaviour and Professor of Psychiatry at the University of Toronto. Vasdev has been featured on Global News, CTV, CNN, New York Times, Toronto Star and the Globe and Mail for his innovative research program.
Saak Victor Ovsepian is an Armenian-Irish neuroscientist best known for his research in neurobiology, neurotherapeutics and translational biosciences. He is a professor in biosciences at the University of Greenwich.
