Fluorodopa F-18 is the amino acid analog fluorodopa (FDOPA) labeled with fluorine F 18, a positron-emitting isotope. It is diagnostic PET agent, which has been used for decades in imaging the loss of dopaminergic neurons in Parkinson's disease, and more recently to detect, stage and restage neuroendocrine tumours and to search for recurrence of viable glioma tissue. Fluorodopa F-18 is able to cross the blood-brain barrier and is taken up by brain tumor cells. As uptake is higher in tumor cells, tumors may then be imaged using positron emission tomography (PET). Assessing tumor uptake of FDOPA may be beneficial for diagnosis, localization and in determining further treatment. The clinical usefulness of Fluorodopa F-18 has been evaluated and recognised in France and subsequently in several EU countries. Fluorodopa F-18 was registered in France in 2006. 6-fluoro-(18F)-L-3,4-dihydroxyphenylalanine (FDOPA) is a large, neutral amino acid that is transported into presynaptic neurons, where it is converted by the enzyme aromatic aminoacid decarboxylase [AAAD]) into fluorodopamine-(18F), which subsequently enters cathecholamine-storage vesicles. 6-fluoro(18F)-L-dopa crosses the blood-brain barrier; therefore, when injected into the blood stream, it reaches the dopaminergic cells in the brain and is used by the brain as a precursor for dopamine. This makes it possible to monitor intracerebral synthesis and uptake of dopamine by means of the positron-emitting 6-fluoro(18F)-L-3,4-dihydroxyphenylalanine (FDOPA), in conjunction with externally-placed devices suited for detection of annihilation photons, which progressively led to the most recent positron emission tomography (PET) units. Iasodopa, the commercial preparation of FDOPA that obtained a marketing authorisation in France in November 2006 (which is currently recognised by several other EU countries), is a solution for injection. The activity available at time of administration ranges from 0.1 GBq to 0.8 GBq per vial. The half-life of the radionuclide is 109.8 min with emission of positron radiation (Emax: 0.633 MeV) followed by photon annihilation radiations of 0.511 MeV.

IOBENGUANE I-123 (AdreView®) is a radiopharmaceutical agent for gamma-scintigraphy. It is similar in structure to the antihypertensive drug guanethidine and to the neurotransmitter norepinephrine (NE). IOBENGUANE is, therefore, largely subject to the same uptake and accumulation pathways as NE. It is taken up by the NE transporter in adrenergic nerve terminals and stored in the presynaptic storage vesicles. IOBENGUANE accumulates in adrenergically innervated tissues such as the adrenal medulla, salivary glands, heart, liver, spleen, and lungs as well as tumors derived from the neural crest. By labeling IOBENGUANE with the isotope iodine 123 (I-123), it is possible to obtain scintigraphic images of the organs and tissues in which the radiopharmaceutical accumulates. IOBENGUANE I-123 (AdreView®) is indicated for use in the detection of primary or metastatic pheochromocytoma or neuroblastoma. It is also used for scintigraphic assessment of sympathetic innervation of the myocardium by measurement of the heart to mediastinum (H/M) ratio of radioactivity uptake in patients with New York Heart Association (NYHA) class II or class III heart failure and left ventricular ejection fraction (LVEF) ≤ 35%. Among these patients, IOBENGUANE I-123 (AdreView®) may be used to help identify patients with lower one and two-year mortality risks, as indicated by an H/M ratio ≥ 1.6.

Fludeoxyglucose F-18 is a positron emitting radiopharmaceutical that is used for diagnostic purposes in conjunction with positron emission tomography (PET) imaging.

Iobenguane I-131 is a radioactive therapeutic agent. The drug contains radioactive isotope I-131, which decays by electron emission with a half-life of about 8 days. By the chemical structure, iobenguane is similar to the neurotransmitter norepinephrine and is subject to the same uptake and regulation pathways. After intravenous administration, iobenguane I-131 accumulates within pheochromocytoma and paraganglioma cells, and radiation from the radioactive decay causes cell death and tumor necrosis. Iobenguane I-131 was approved by the FDA for the treatment of adult and pediatric patients with iobenguane scan positive, unresectable, locally advanced or metastatic pheochromocytoma or paraganglioma who require systemic anticancer therapy. Iobenguane I-131 is investigated in clinical trials as a treatment of neuroblastoma, ganglioneuroblastoma and other tumors of neuroendocrinal origin.

Fluoroethylcholine ion F-18 is ethylcholine labeled with fluorine F 18, a positron-emitting isotope. Fluorine F18 fluoroethylcholine incorporates into tumor cells through an active, carrier-mediated transport mechanism for choline and then is phosphorylated intracellularly by choline kinase, yielding a phosphoryl derivative, and finally is integrated into cellular phospholipids, probably primarily into a phosphatidyl derivative; concentration of this agent in tumor cells as various fluorine F 18 fluoroethylcholine derivatives enables tumor imaging using positron emission tomography (PET). Choline kinase, the enzyme responsible for the phosphorylation of choline, is frequently up-regulated in human tumor cell lines. F18-fluoroethylcholine is used for imaging of prostate cancer and brain tumors, mainly in Europe and Japan.

Fluorocholine-F18 is a tracer for positron emission tomography that can be used in oncology for the evaluation of metastatic prostate cancer, hepatocellular carcinoma, and recurrent brain tumor. After crossing the cell membrane by a carrier-mediated mechanism, Fluorocholine-F18 is converted to cytidinediphosphatecholine and incorporated into phosphatidylcholine which is a component of the cell membrane. This process has been found to be upregulated in malignant cells, providing a mechanism for the enhanced accumulation of radiolabelled choline by neoplasms.

Indium In-111 is used in specialized diagnostic applications, for example, with indium-111 labelled antibodies. It is useful for labelling blood cell components. Other applications include labelling of platelets for thrombus detection, labelled leukocytes for localization of inflammation and abscesses, as well as leukocyte kinetics. Indium forms a saturated (1:3) complex with oxyquinoline. The complex is neutral and lipidsoluble, which enables it to penetrate the cell membrane. Within the cell, indium becomes firmly attached to cytoplasmic components; the liberated oxyquinoline is released by the cell. It is thought likely that the mechanism of labeling cells with indium In 111 oxyquinoline involves an exchange reaction between the oxyquinoline carrier and subcellular components which chelate indium more strongly than oxyquinoline. Indium In-111 oxyquinoline is indicated for radiolabeling autologous leukocytes. Indium In-111 oxyquinoline labeled leukocytes may be used as an adjunct in the detection of inflammatory processes to which leukocytes migrate, such as those associated with abscesses or other infection, following reinjection and detection by appropriate imaging procedures. The degree of accuracy may vary with labeling techniques and with the size, location and nature of the inflammatory process. Sensitivity reactions (urticaria) have been reported. The presence of fever may mask pyrogenic reactions from indium In 111 oxyquinoline labeled leukocytes. Indium In-111 Chloride is a diagnostic radiopharmaceutical intended for radiolabeling OncoScint (satumomab pendetide) or ProstaScint (capromab pendetide) used for in vivo diagnostic imaging procedures and for radiolabeling Zevalin (ibritumomab tiuxetan) in preparations used for radioimmunotherapy procedures.

Molybdenum-99 (99Mo, half-life = 66 h) is a parent radionuclide of a diagnostic nuclear isotope. It decays in technetium-99 m (half-life = 6 h), which is used in over 30 million procedures per year around the world. Between 95 and 98 percent of Mo-99 is currently being produced using highly enriched uranium (HEU) targets. Other medical isotopes such as iodine-131 (I-131) and xenon-133 (Xe-133) are by-products of the Mo-99 production process and will be sufficiently available if Mo-99 is available.

FLUORIDE ION F-18 (as sodium fluoride F-18) is a radioactive diagnostic agent for positron emission tomography (PET) indicated for imaging of bone to define areas of altered osteogenic activity. FLUORIDE ION F-18 normally accumulates in the skeleton in an even fashion, with greater deposition in the axial skeleton (e.g. vertebrae and pelvis) than in the appendicular skeleton and greater deposition in the bones around joints than in the shafts of long bones. Increased FLUORIDE ION F-18 deposition in the bone can occur in areas of increased osteogenic activity during growth, infection, malignancy (primary or metastatic) following trauma, or inflammation of the bone.