PET Positron Emission Tomography

The radionuclide most frequently used in SPET is either for static inves- 

Less frequently used radionuclides are (e.g. static investigation of thyroid function, dynamic investigation of renal function), Xe (dynamic investigation of pulmonary emphysema) and 20171 (e.g. static investigation of cardiac infarction and ischaemia). 

In positron emission tomography (PET) the two SllkeV y-ray photons emitted simultaneously in opposite directions are registered by y-ray detectors, indicating that the positron decay must have occurred somewhere along the line between these two detectors. The same holds for other events of positron decay, and the radionuclide can be localized at the intersection of these lines. 

The patients are positioned inside a ring of about 50 to 100 scintillation detectors, and the ring is rotated and moved in a programmed maimer. As in SPET, the results are evaluated by computer software to give a three-dimensional picture of the distribution of the radionuclide in the organ of interest. The resolution is also of the order of 1 mm. 

Positron emitters most frequently used for positron emission tomography (PET) are listed in Table 19.2. As already mentioned in section 19.5, production of these positron emitters requires the availability of a suitable cyclotron, fast chemical separation techniques and fast syntheses. 

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Applications in agrochemicals [42, 43], pharmaceuticals [44,45], and positron emission tomography (PET) [46, 47, 48 49] have resulted in the resuscitation of the Wallach reaction The Wallach technique provides high-specific-activity F-radiolabeled aromatic fluoride for PET studies, in contrast to the low-specific-ac-tivity product by the Balz-Schiemann route... 

Positron emission tomography (PET), 516 Post-transition metal Lower members of periodic groups 13,14, and 15, such as PbandBi, 31,38-39... 

An additional benefit of COMT inhibitors can be found in positron emission tomography (PET) studies. In PET, using 6-[18F]-fluoro-L-dopa (6-FD) to visualize the brain dopamine metabolism, the peripheral formation of 3-0-methyl-6-[18F]-fluoro-L-dopa (3-OMFD) by COMT is harmful. 3-OMFD contaminates the brain radioactivity analysed since it is easily transported like 3-OMD to the... 

Brain imaging technique that allows visualization of the brain, in order to understand which brain regions are involved in specific functions. Its functioning is based on the measurement of the regional cerebral blood flow which increases when a specific brain region is activated. Its use is similar to that of positron emission tomography (PET). 

Positron emission tomography (PET) is an imaging technique that relies on the emission of positrons from radionucleotides tagged to an injectable compound of interest. Each positron emitted by the radioisotope collides with an electron to emit two photons at 180° from each other. The photons are detected and the data processed so that the source of the photons can be identified and an image generated showing the anatomical localization of the compound of interest. 

Positron emission tomography (PET) makes use of a short-lived positron emitter such as fluorine-18 to image human tissue with a degree of detail not possible with x-rays. It has been used extensively to study brain function (see illustration) and in medical diagnosis. For example, when the hormone estrogen is labelled with fluorine-18 and injected into a cancer patient, the fluorine-bearing compound is preferentially absorbed by the tumor. The positrons given off by the fluorine atoms are quickly annihilated when they meet... 

In their search for new hgands with a very high binding affinity for the nicotinic acetylchohne receptor (nAChR), potentially useful in positron emission tomography (PET) when radiolabeled with [ F], Horti et al. described the synthesis of BOC-protected 5-(azetidin-2-ylmethoxy)-2-chloro-6 -fluoro-3,3 -bipyridine via a sequential classical heating and microwave irradiation of (2-fluoro-5-pyridinyl)(trimethyl)stannane with f-butyl 2- [(6-chloro-5-... 

One of the great challenges facing medical science is how to diagnose and treat afflictions of the brain such as Alzheimer s disease, hi part this is because we cannot see directly inside an active human brain. Recently, however, medical researchers have developed a powerful diagnostic tool called positron emission tomography (PET). 

Mysteries such as this attract young people to science. Nuclear physics, however, tends to turn people off Nuclear power plant malfunctions and atomic bombs are frightening. Nevertheless, humankind has greatly benefited from scientific investigations of the nucleus. Science s hard-won knowledge of the atomic nucleus is used extensively in medicine, from imaging procedures such as positron emission tomography (PET) to radiation therapy, which has saved the lives of many cancer patients. 

Positron emission tomography (PET) A medical imaging technique that helps physicians locate tumors and other growths in the body. A radioactive tracer isotope which emits a positron is incorporated into a metaholically active molecule. A scanner locates the tissues where the radioactive substance winds up. 

Radiologic scans x-rays, computed tomographic (CT) scans, magnetic resonance imaging (MRI), positron-emission tomography (PET)... 

Positron emission tomography (PET) scan A scan that produces images of the body after the injection of a radioactive form of... 

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