Carbon-11 choline is the basis of

medical imaging Medical imaging is the technique and process of imaging the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues (physiology). Medical imaging seeks to revea ...

technologies. Because of its involvement in biologic processes,

choline Choline is a cation with the chemical formula . Choline forms various Salt (chemistry), salts, such as choline chloride and choline bitartrate. An essential nutrient for animals, it is a structural component of phospholipids and cell membrane ...

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 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, re ...

. 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. Choline occurs in the head groups of phosphatidylcholine and sphingomyelin, which are abundant in cell membranes">sphingomyelin.html" ;"title="phosphatidylcholine and sphingomyelin">phosphatidylcholine and sphingomyelin, which are abundant in cell membranes. It is the precursor for the neurotransmitter acetylcholine.

Specific applications

One of the first uses of carbon-11 choline in PET imaging examined Alzheimer's disease patients. Choline is the precursor to neurotransmitter acetylcholine whose cholinergic activity is impaired in many neurodegenerative diseases including Alzheimer’s. While there was uptake of the tracer in the brain, no pharmacokinetic pattern was found. Carbon-11 choline has found more success in cancer systems imaging. Choline is a precursor for the synthesis of

phospholipids Phospholipids are a class of lipids whose molecule has a hydrophilic "head" containing a phosphate group and two hydrophobic "tails" derived from fatty acids, joined by an alcohol residue (usually a glycerol molecule). Marine phospholipids typi ...

. When a cell is about to divide, it synthesizes these phospholipids to generate enough material to build the

cell membranes The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extra ...

of the two daughter cells. Thus it was hypothesized that highly proliferative tumors would uptake more choline than the surrounding healthy tissue. This was first tested in brain tumors after successful demonstration of choline uptake in the brain. It was found that these brain tumors had over 10x the uptake of carbon-11 choline than the surrounding brain tissue. Furthermore, because of the low choline uptake in healthy brain tissue, carbon-11 choline was found to be a superior PET tracer than fluorine-18

Fludeoxyglucose []Fluorodeoxyglucose (International Nonproprietary Name, INN), or fluorodeoxyglucose F 18 (United States Adopted Name, USAN and United States Pharmacopeia, USP), also commonly called fluorodeoxyglucose and abbreviated []FDG, 2-[]FDG o ...

(FDG) when delineating brain tumors. Carbon-11 choline has also been used to detect tumors in the colon and esophagus and lung metastases. Prostate cancer is another disease where carbon-11 choline PET imaging has found success. As with the brain, there is too much signal from the surrounding tissue, especially the bladder, to accurately measure tumor uptake with fluorine-18 FDG. While it was shown carbon-11 choline could be used to detect the initiation of prostate cancer, its value was found in detecting prostate cancer recurrence when it is the most deadly. In 2012, the U.S. Food and Drug Administration approved carbon-11 choline as an imaging agent to be used during a PET scan to detect recurrent prostate cancer.{{cite web, url=https://www.drugs.com/pro/choline-c-11.html, title=Choline C-11, publisher=Drugs.com, date=3 November 2016, accessdate=9 January 2017

References

Quaternary ammonium compounds 3D nuclear medical imaging Medical physics