Positron-emitting tracers

Hydroponic culture containing a positron-emitting tracer,... 

Figure 35 Schematic of positron-emitting tracer imaging system (PETIS) and an example of experimental setup.

Hara T, Yuasa M (1999). Automated synthesis of [nC] Choline, a positron-emitting tracer for tumor imaging. Appl Radiat Isot 50 531 Huisman MC, Higuchi T, Reder S et al (2008). Initial characterization of an 18F-labled myocardial perfusion tracer. J Nucl Med 49 630 Kabalka GW, Lambrecht RM, Fowler JS et al (1985). Synthesis of 150-labelled butanol via organoborane chemistry. Appl Radiat Isot 36 853 Kamarainen EL, Kyllonen T, Nihtila O et al (2004). Preparation of fluorine-18 labeled fluoromisonidazole using two different synthesis methods. J Labeled Comp Radiopharm 47 37... 

Fig. 12.1 Dual detector system for measuring positron-emitting tracers In the brain.

One can use a low spatial resolution detector system, because the naltrexone blocks all p opiate receptors in the brain regardless of their location, and they are widespread throughout the brain. Probe devices for use with positron-emitting tracers have been used frequently to study mice, rats, dogs, baboons, and humans. In living mice, it was possible to obtain a dose-response curve for haloperidol on the binding of [ C]M-methyl spiperone. Similar dose/response curves were obtained in humans, and the results correlated well with PET imaging studies of the same persons. 

Monoamine oxidase inhibitors, such as SSRIs, have been shown to be effective in the treatment of depression, and they have become among the most widely used prescription drugs in the United States. Prozac is used not only to treat major depressive disorders but also bulimia nervosa, obsessive-compulsive disorder, panic disorder, and premenstrual dysphoric disorder. Multiple serotonin receptor subtypes are involved. Specific serotonin receptor subtype agonists and antagonists have been radiolabeled with positron-emitting tracers to assess the state of the serotonergic system. 

Kara T, Yuasa M. Automated synthesis of [1 ICjcholine, a positron-emitting tracer for tumor imaging. Appl Radiat Isot 1999 50 531-533. 

The acronym PET can be used to stand for both positron-emitting tracers and positron emission tomography it is a representation of the radioactive isotopes used and the methods by which their distri-hution is visualized (tomography derives from the Greek tomos or cut - i.e. an imaged slice through... 

Carbon-11 has a very short half-life (just 20.4min) but the chance to substitute a carbon atom in any biological molecule by a positron-emitting nC is a very interesting possibility. This has led to a substantial development of nC-labeled tracers. The short half-life conditions everything and only PET centers equipped with a cyclotron can have a chnical program with nC tracers. The production of the radiopharmaceutical must in these cases be performed just before the imaging study and is usually not started until the patient is already on the PET scanner. 

Touring the past decade a number of research laboratories have devel-oped procedures for the rapid synthesis of amino acids labeled with short-lived, positron-emitting radionuclides. These tracers make possible the study of regional amino-acid metabolism in the living organism by external detection of the y photons produced by positron annihilation. This decay mode also permits the determination of label distribution in transverse sections through the body by means of positron emission... 

PET can be used to measure quantitatively the chemical composition of tissues of the body by using appropriately selected compounds labeled with positron-emitting radioisotopes that rapidly distribute between the blood and the tissue of interest. The measurement is based on the determination of the tissue-to-blood partition coeflBcient of the tracer at equilibrium. Knowledge of the tissue-to-blood partition coeflBcient plus the concentration of the compoimd of interest in the vascular compartment permits the calculation of the actual tissue concentration. This concept has been tested by measuring brain carbon dioxide content using C-labeled carbon dioxide as a tracer (31). These measurements were... 

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