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Radiopharmaceuticals for Diagnostics
Published in Michael Ljungberg, Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
The preparation of RPs can be subdivided into 3 steps: Radiochemistry: During the radiolabelling with PET-radionuclides, a reaction/complexation between a precursor molecule and the radiolabelled chemical entity occurs preferably at the latest stage possible. Radiolabelling can occur directly with the radionuclide obtained from the cyclotron or generator, or a small PET-labelled synthon is prepared first, followed by a second reaction step.Purification: After the radiolabelling steps, which are considered to be the radiochemistry part, the radiolabelled product needs to be isolated from (radio)chemical impurities. This is mostly achieved by High Performance Liquid Chromatography (HPLC) or by using Solid Phase Extraction (SPE) cartridges.Reformulation: Finally, a reformulation step is carried out to make sure that the RP is injected in a proper and safe form, and thereafter the solution is sterilized by passing through a 0.22 um sterile filter.
Applications for Drug Development
Published in George C. Kagadis, Nancy L. Ford, Dimitrios N. Karnabatidis, George K. Loudos, Handbook of Small Animal Imaging, 2018
Jessica Kalra, Donald T. Yapp, Murray Webb, Marcel B. Bally
Radiolabeled drugs can be used to determine whether drugs appropriately target, bind to, or are taken up through receptor interactions with the targeted cells. As an example, it is known that some breast cancer patients who have Her2/neu-positive cancers are intrinsically insensitive to trastuzumab, the therapeutic monoclonal antibody used in combination with other broad-spectrum anticancer drugs to treat patients with Her2/neu-positive cancers (Figueroa-Magalhaes et al. 2014). To query the mechanism of this resistance, researchers asked whether these patients may be insensitive to the drug because it fails to bind to Her2/neu-positive cells in situ. To answer this question, Ferreira et al. developed a 64Cu radiolabeled trastuzumab that can be used with PET imaging to evaluate biodistribution of trastuzumab in vivo (Ferreira et al. 2010). This technology also has the potential to be rapidly translated into clinical applications.
Environmental Fate Models, with Emphasis on Those Applicable to Air
Published in James N. Seiber, Thomas M. Cahill, Pesticides, Organic Contaminants, and Pathogens in Air, 2022
James N. Seiber, Thomas M. Cahill
Chamber models, such as those discussed above, are typically used in a lab/greenhouse/field plot setting. They allow control of some variables and, in some cases, can incorporate radiolabeled compounds. They are good for ranking chemicals in terms of such parameters as biodegradability and ecological magnification. They are also good for understanding how structures and key physicochemical properties influence behavior and fate. The data set accumulated over the years from using these model systems has been converted into computer code for relatively rapid estimation of chemical environmental fate using numeric models. Although they are time-consuming and labor-intensive, chamber models are still used as needed (e.g., to validate a computer model).
Nuclear Medicine in Oncology
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2018
Carla Oliveira, Rui Parafita, Ana Canudo, Joana Correia Castanheira, Durval C. Costa
In summary, the major oncologic diagnostic and therapeutic applications of Nuclear Medicine discussed in this review are:lymphoscintigraphy with sentinel lymph node mapping aids surgery, which aims at avoiding unnecessary lymph node group removal, and is recommended in tumours with no demonstration of lymph node metastasis;equilibrium radionuclide angiography is a procedure that is reproducible and independent from the operator and enables monitoring of the left ventricular function, critical in patients undergoing cardiotoxic therapy;renal scintigraphy with 99mTc-DTPA and in vivo and in vitro calculation of the glomerular filtration rate with this radiopharmaceutical enable the early detection of slight reductions in the glomerular function, which must be monitored in patients undergoing nephrotoxic treatment;bone scintigraphy is a highly sensitive exam in mapping bone metastases with mainly osteoblastic features;whole body scintigraphy with 123I-MIBG enables staging, restaging and assessing the response to therapy in tumours of the sympathetic-adrenal axis;positron emission tomography allows for, among other recommendations, staging, restaging and assessing the response to treatment, as well as planning radiotherapy in certain tumours, and the type of tumour at stake is decisive for deciding which radiopharmaceutical to use;in the field of treatment, 131I is necessary for the ablation of residual thyroid tissue after surgery (except in low risk patients) and constitutes a first order option for metastases or suspicion of relapse of differentiated thyroid carcinoma;131I-MIBG and radiolabelled conjugated peptides are therapeutic options in plurimetastasised tumours that present avidity towards these radiopharmaceuticals, particularly tumours of the sympathetic-adrenal axis and neuroendocrine tumours of the digestive system, respectively;153Sm-EDTM, 89Sr and 223Ra-Cl2 are therapeutic options in palliative care for bone pain due to osteoblastic metastasis with no response to conventional treatment; the latter has the advantages of a high level of tolerability (in terms of side effects) and a three-month increase in the average life expectancy of patients.