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Images from Radioactivity: Radionuclide Scans, SPECT, and PET
Published in Suzanne Amador Kane, Boris A. Gelman, Introduction to Physics in Modern Medicine, 2020
Suzanne Amador Kane, Boris A. Gelman
PET also has a significant advantage in the types of positron-emitting radiolabels available. The radionuclides used include oxygen-15, carbon-11, nitrogen-13, fluorine-18, gallium-68, and rubidium-82 (Table 6.4). This list includes elements – carbon, oxygen, and nitrogen – that are major constituents of the body's organic compounds. Thus, it is possible to synthesize radiolabeled versions of naturally occurring body chemicals, drugs, or other molecules with their biochemical properties intact. Fluorine can be readily incorporated into many drugs and naturally occurring molecules as a substitute for hydrogen. For example, the fluorine-18-labeled sugar fluorodeoxyglucose (FDG) is metabolized by brain cells in place of the naturally occurring sugar glucose, so PET can detect the distribution of the radioactive sugar in the brain to show which regions are most metabolically active, and hence using the greatest amount of energy. Similarly, blood flow to the brain can be visualized either by using carbon dioxide labeled with oxygen-15 or carbon-11, or water labeled with oxygen-15 incorporated into the bloodstream. The brain's use of oxygen also can be monitored using oxygen-15. Since changes in the blood supply locally within the brain are assumed to reflect variations in its activity, these measurements give clues to which regions are most active at any moment. While they are not native to the body, the more exotic elements on the list are used as chemical labels for interesting molecules. For example, rubidium-82 is used in cardiac imaging to map the health of heart muscle, while gallium-68 is a useful label for drugs.
Non-invasive imaging techniques to assess myocardial perfusion
Published in Expert Review of Medical Devices, 2020
Olivier Villemain, Jérôme Baranger, Zakaria Jalal, Christopher Lam, Jérémie Calais, Mathieu Pernot, Barbara Cifra, Mark K. Friedberg, Luc Mertens
Different SPECT and PET radiotracers can be used for NMPI each with its advantages and disadvantages [20]. NMPI radiotracers show a linear relationship between peak stress MBF and myocardial tracer concentration uptake. The commonly used MPI SPECT tracers are Thallium-201 (201Tl), Technetium-99 m Sestamibi (99 mTc-MIBI) and Technetium-99 m-Tetrofosmin. The main MPI PET tracers are 13 N-ammonia (13 N-NH3), Oxygen-15-water (15O-H2O), rubidium-82 (82Rb) and Fluorine-18 (18 F)-flurpiridaz (Figure 4).