Editing Positron emission tomography (section)

=== Oncology ===
[[File:PET-MIPS-anim.gif|thumb|upright|Whole-body PET scan using {{chem|18|F}}-FDG ([[fluorodeoxyglucose]]). The normal brain and kidneys are labeled, and radioactive urine from breakdown of the FDG is seen in the bladder. In addition, a large metastatic tumor mass from colon cancer is seen in the liver.]]
PET scanning with the radiotracer [[Fluorodeoxyglucose (18F)|[<sup>18</sup>F]fluorodeoxyglucose]] (FDG) is widely used in clinical oncology. FDG is a [[glucose]] [[analog (chemistry)|analog]] that is taken up by glucose-using cells and phosphorylated by [[hexokinase]] (whose [[mitochondrial]] form is significantly elevated in rapidly growing [[malignant]] tumors).<ref>{{cite journal |vauthors=Bustamante E, Pedersen P |title=High aerobic glycolysis of rat hepatoma cells in culture: role of mitochondrial hexokinase |journal=Proc Natl Acad Sci USA |volume=74 |issue=9 |pages=3735–9 |year=1977 |pmid=198801 |doi=10.1073/pnas.74.9.3735 |pmc=431708 |bibcode=1977PNAS...74.3735B|doi-access=free }}</ref> [[Metabolic trapping]] of the radioactive glucose molecule allows the PET scan to be utilized. The concentrations of imaged FDG tracer indicate tissue metabolic activity as it corresponds to the regional glucose uptake. FDG is used to explore the possibility of cancer spreading to other body sites ([[cancer]] [[metastasis]]). These FDG PET scans for detecting cancer metastasis are the most common in standard medical care (representing 90% of current scans). The same tracer may also be used for the diagnosis of types of [[dementia]]. Less often, other [[radioactive tracers]], usually but not always labelled with [[fluorine-18]] (<sup>18</sup>F), are used to image the tissue concentration of different kinds of molecules of interest inside the body.{{citation needed|date=November 2023}}

A typical dose of FDG used in an oncological scan has an effective radiation dose of 7.6&nbsp;[[millisievert|mSv]].<ref name="Exposure">ARSAC – Notes for Guidance on the Clinical Administration of Radiopharmaceuticals and use of Sealed Sources (March 2018 p.35)</ref> Because the hydroxy group that is replaced by fluorine-18 to generate FDG is required for the next step in [[Glycolysis#Sequence of reactions|glucose metabolism]] in all cells, no further reactions occur in FDG. Furthermore, most tissues (with the notable exception of liver and kidneys) cannot remove the [[phosphate]] added by hexokinase. This means that FDG is trapped in any cell that takes it up until it decays, since [[phosphorylation|phosphorylated]] sugars, due to their ionic charge, cannot exit from the cell. This results in intense radiolabeling of tissues with high glucose uptake, such as the normal brain, liver, kidneys, and most cancers, which have a higher glucose uptake than most normal tissue due to the [[Warburg effect (oncology)|Warburg effect]]. As a result, FDG-PET can be used for diagnosis, staging, and monitoring treatment of cancers, particularly in [[Hodgkin lymphoma]],<ref>{{cite journal | vauthors = Zaucha JM, Chauvie S, Zaucha R, Biggii A, Gallamini A | title = The role of PET/CT in the modern treatment of Hodgkin lymphoma | journal = Cancer Treatment Reviews | volume = 77 | pages = 44–56 | date = July 2019 | pmid = 31260900 | doi = 10.1016/j.ctrv.2019.06.002 | s2cid = 195772317 }}</ref> [[non-Hodgkin lymphoma]],<ref>{{cite journal | vauthors = McCarten KM, Nadel HR, Shulkin BL, Cho SY | title = Imaging for diagnosis, staging and response assessment of Hodgkin lymphoma and non-Hodgkin lymphoma | journal = Pediatric Radiology | volume = 49 | issue = 11 | pages = 1545–1564 | date = October 2019 | pmid = 31620854 | doi = 10.1007/s00247-019-04529-8 | s2cid = 204707264 }}</ref> and [[lung cancer]].<ref>{{Cite journal| vauthors = Pauls S, Buck AK, Hohl K, Halter G, Hetzel M, Blumstein NM, Glatting G, Krüger S, Sunder-Plassmann L, Möller P, Hombach V | display-authors = 6 |date=2007|title=Improved non-invasive T-Staging in non-small cell lung cancer by integrated <sup>18</sup>F-FDG PET/CT |journal=Nuklearmedizin|volume=46|issue=1|pages=09–14|doi=10.1055/s-0037-1616618| s2cid = 21791308 |issn=0029-5566}}</ref><ref>{{cite book | vauthors = Steinert HC | chapter = PET and PET–CT of Lung Cancer | title = Positron Emission Tomography | volume = 727 | pages = 33–51 | date = 2011 | pmid = 21331927 | doi = 10.1007/978-1-61779-062-1_3 | publisher = Humana Press | isbn = 978-1-61779-061-4 | series = Methods in Molecular Biology }}</ref><ref>{{cite journal | vauthors = Chao F, Zhang H | title = PET/CT in the staging of the non-small-cell lung cancer | journal = Journal of Biomedicine & Biotechnology | volume = 2012 | pages = 783739 | date = 2012 | pmid = 22577296 | pmc = 3346692 | doi = 10.1155/2012/783739 | doi-access = free }}</ref>

A 2020 review of research on the use of PET for Hodgkin lymphoma found evidence that negative findings in interim PET scans are linked to higher [[overall survival]] and [[progression-free survival]]; however, the certainty of the available evidence was moderate for survival, and very low for progression-free survival.<ref>{{cite journal | vauthors = Aldin A, Umlauff L, Estcourt LJ, Collins G, Moons KG, Engert A, Kobe C, von Tresckow B, Haque M, Foroutan F, Kreuzberger N, Trivella M, Skoetz N | display-authors = 6 | title = Interim PET–results for prognosis in adults with Hodgkin lymphoma: a systematic review and meta-analysis of prognostic factor studies | journal = The Cochrane Database of Systematic Reviews | volume = 1 | issue = 1 | pages = CD012643 | date = January 2020 | pmid = 31930780 | pmc = 6984446 | doi = 10.1002/14651858.CD012643.pub3 | doi-access = free | collaboration = Cochrane Haematology Group }}</ref>

A few other isotopes and radiotracers are slowly being introduced into oncology for specific purposes. For example, {{anchor|Metomidate}}[[Carbon-11|<sup>11</sup>C]]-labelled [[metomidate]] (11C-metomidate) has been used to detect tumors of [[adrenocortical]] origin.<ref>{{cite journal | vauthors = Khan TS, Sundin A, Juhlin C, Långström B, Bergström M, Eriksson B | title = 11C-metomidate PET imaging of adrenocortical cancer | journal = European Journal of Nuclear Medicine and Molecular Imaging | volume = 30 | issue = 3 | pages = 403–10 | date = March 2003 | pmid = 12634969 | doi = 10.1007/s00259-002-1025-9 | s2cid = 23744095 }}</ref><ref>{{cite journal | vauthors = Minn H, Salonen A, Friberg J, Roivainen A, Viljanen T, Långsjö J, Salmi J, Välimäki M, Någren K, Nuutila P | display-authors = 6 | title = Imaging of adrenal incidentalomas with PET using (11)C-metomidate and (18)F-FDG | journal = Journal of Nuclear Medicine | volume = 45 | issue = 6 | pages = 972–9 | date = June 2004 | pmid = 15181132 | url = http://jnm.snmjournals.org/cgi/content/full/45/6/972 }}</ref> Also, [[fluorodopa]] (FDOPA) PET/CT (also called F-18-DOPA PET/CT) has proven to be a more sensitive alternative to finding and also localizing [[pheochromocytoma]] than the [[iobenguane]] (MIBG) [[MIBG scan|scan]].<ref>{{cite journal | vauthors = Pacak K, Eisenhofer G, Carrasquillo JA, Chen CC, Li ST, Goldstein DS | title = 6-[<sup>18</sup>F]fluorodopamine positron emission tomographic (PET) scanning for diagnostic localization of pheochromocytoma | journal = Hypertension | volume = 38 | issue = 1 | pages = 6–8 | date = July 2001 | pmid = 11463751 | doi = 10.1161/01.HYP.38.1.6 | doi-access = free }}</ref><ref>{{cite journal|url=https://emedicine.medscape.com/article/379861-overview|title=Pheochromocytoma Imaging: Overview, Radiography, Computed Tomography|date=10 August 2017|via=eMedicine}}</ref><ref name="pmid19862519">{{cite journal | vauthors = Luster M, Karges W, Zeich K, Pauls S, Verburg FA, Dralle H, Glatting G, Buck AK, Solbach C, Neumaier B, Reske SN, Mottaghy FM | display-authors = 6 | title = Clinical value of <sup>18</sup>F-fluorodihydroxyphenylalanine positron emission tomography/computed tomography (<sup>18</sup>F-DOPA PET/CT) for detecting pheochromocytoma | journal = European Journal of Nuclear Medicine and Molecular Imaging | volume = 37 | issue = 3 | pages = 484–93 | date = March 2010 | pmid = 19862519 | doi = 10.1007/s00259-009-1294-7 | s2cid = 10147392 }}</ref>