Imaging Techniques
Manoj Ramachandran, Tom Nunn in Basic Orthopaedic Sciences, 2018
Its basic components are: Cyclotron – machine that produces positron emitting isotopes e.g. nitrogen-13, oxygen-15, carbon-11, fluorine-18. The isotope is then tagged to a naturally occurring chemical such as glucose, water or ammonia depending on the indication for the scan. This radiotracer is then injected into the patient. For example, fluorodeoxyglucose (FDG) is a radiotracer used to analyse glucose utilization.Camera – as the radiotracer undergoes positron emission decay, positrons travel in tissues to interact with electrons within the tissues (positron annihilation event). This produces a back-to-back emission of two gamma rays that travel in opposite directions (180°) on the same axis. The gamma detectors used are sensitive only to such gamma rays.Computer – the data collected is then reconstructed to form an image.
Fate of Radiometabolites
Lelio G. Colombetti in Principles of Radiopharmacology, 1979
Radioactive gases are eliminated by the lungs with a rate following the breathing. Radiometabolites are scarcely eliminated with the expired air, unless they are formed of CO2. It has been shown, in animals, that 14CO2 and 14CH4 have been detected after injection of a molecule containing an amino (carbon 14) methyl group: −NH14CH3. The elimination of 11CO2 is observed in certain circumstances when patients are given carbon 11 radiotracers with such radicals. The use of nitrogen 13 amino acids may lead to the expiration of ammoniac gas 13NH3.
Small Animal Imaging and Therapy
George C. Kagadis, Nancy L. Ford, Dimitrios N. Karnabatidis, George K. Loudos in Handbook of Small Animal Imaging, 2018
The major strength of PET imaging is that radionuclides such as carbon-11, nitrogen-13, or oxygen-15 can be incorporated in the molecule with minimal interference to the function of pharmaceuticals. This allows for developing radiolabeled probes, which are chemically almost identical to the parent compounds. This strategy has been successfully employed to develop PET tracers, which can pass the blood–brain barrier and can be used for imaging brain function (Judenhofer et al. 2008; Mariani et al. 2010).
Marie and Irène Curie, two brilliant women who pioneered the development of nuclear chemistry, radiotherapy, and radiobiology
Published in International Journal of Radiation Biology, 2022
Marek K. Janiak, Carmel Mothersill
Likewise, the Nobel Prize-winning accomplishment of Irène and Frédéric Joliot-Curie stemmed from the earlier work of and guidance by Marie and Pierre Curie. Ironically, as put by one of her Polish biographers, ‘Marie Curie’s life expired at the moment when the world was fired with the discovery of her daughter.’ (Pospieszny 2017). The creation in 1934 of ‘artifical’1 (i.e. non-existing in nature) radioactive istopes of phosphorous (30P), nitrogen (13N), and silicon (27Si) significantly stimulated the development of radiation chemistry and radiochemistry. Soon, Enrico Fermi and others followed suit and produced other ‘man-made’ radioisotopes which today can be counted in hundreds (Pawłowski 1956). Many of these are used for diagnosis and treatment of diseases (most importantly cancer) and some of them also turned out as useful tools for studying biomedical effects of ionizing radiation. Albert Einstein in his eulogy to Marie Curie (who died in November of the following year after the Joliot-Curie’s discovery) said, ‘Madam Curie was very happy seeing that the work of her life has been undertaken by her dauhter Irène Curie who equales her mother in scientific talent and achievements.’ (Hurwic 1954).
Advantages and limitations of amino acid PET for tracking therapy response in glioma patients
Published in Expert Review of Neurotherapeutics, 2020
Karl-Josef Langen, Alexander Heinzel, Philipp Lohmann, Felix M. Mottaghy, Norbert Galldiks
Therefore, a number of diagnostic approaches with a focus on metabolic and functional imaging methods are under investigation [3]. Positron emission tomography (PET) is a well-established method in nuclear medicine that is able to detect the distribution of radiolabelled molecules in the human body with high sensitivity and a spatial resolution of 3–5 mm. Since numerous metabolic substrates, receptor ligands or pharmaceuticals can be labeled with positron-emitting isotopes such as carbon-11, nitrogen-13 or fluorine-18, PET offers great potential for the assessment of metabolic and physiological processes. However, radiolabelling of the molecules with short-lived positron emitters is a rather sophisticated procedure. In addition, the tracers must meet a number of conditions such as high in vivo stability, high specificity and a sufficient residence time in the target tissue in order to be clinically useful.
COVID-19 presenting with myocardial infarction with nonobstructive coronary arteries
Published in Baylor University Medical Center Proceedings, 2022
Mahmoud Ismayl, Dua Noor Butt, Akshay Machanahalli Balakrishna, Omar Kousa, Amjad Kabach
Electrocardiography revealed normal sinus rhythm without ST-segment changes (Figure 1a). The high-sensitivity cardiac troponin was 10.9 ng/L but subsequently rose to 41,331 ng/L. Total cholesterol was 176 mg/dL; low-density lipoprotein, 86 mg/dL; high-density lipoprotein, 70 mg/dL; triglycerides, 101 mg/dL; and hemoglobin A1C, 5.4%. A basic metabolic panel showed a sodium of 136 mmol/L; potassium, 3.2 mmol/L; chloride, 105 mmol/L; creatinine, 0.86 mg/dL; blood urea nitrogen, 13 mg/dL; and glucose, 99 mg/dL. A complete blood count showed a white blood cell count of 8.7 k/μL; hemoglobin, 14.2 g/dL; and platelets, 260 k/μL. Echocardiography revealed a left ventricular ejection fraction of 55% to 60% with multiple segmental wall motion abnormalities. The patient was treated for non–ST elevation MI with aspirin, ticagrelor, high-intensity statin, heparin, and metoprolol succinate and was given nitroglycerin for pain relief. A coronary angiogram revealed normal coronary arteries and an incidental anomalous left circumflex coronary artery originating from the ostial right coronary artery with a retroaortic course to the left atrioventricular sulcus (Figure 1b).
Related Knowledge Centers
- Ammonia
- Cyclotron
- Nuclear Reaction
- Positron Emission Tomography
- Radionuclide
- Nitrogen
- Half-Life
- Myocardial Perfusion Imaging
- Cno Cycle