C-11 radiochemistry in cancer imaging applications.
Carbon-11 (C-11) radiotracers are widely used for the early diagnosis of cancer, monitoring therapeutic response to cancer treatment, and pharmacokinetic investigations of anticancer drugs. PET imaging permits non-invasive monitoring of metabolic processes and molecular targets, while carbon-11 radiotracers allow a "hot-for cold" substitution of biologically active molecules. Advances in organic synthetic chemistry and radiochemistry as well as improved automated techniques for radiosynthesis have encouraged investigators in developing carbon-11 tracers for use in oncology imaging studies. The short half-life of carbon-11 (20.38 minutes) creates special challenges for the synthesis of C-11 labeled tracers; these include the challenges of synthesizing C-11 target compounds with high radiochemical yield, high radiochemical purity and high specific activity in a short time and on a very small scale. The optimization of conditions for making a carbon-11 tracer include the late introduction of the C-11 isotope, the rapid formation and purification of the target compound, and the use of automated systems to afford a high yield of the target compound in a short time. In this review paper, we first briefly introduce some basic principles of PET imaging of cancer; we then discuss principles of carbon-11 radiochemistry, focus on specific advances in radiochemistry, and describe the synthesis of C-11 radiopharmaceuticals developed for cancer imaging. The carbon-11 radiochemistry approaches described include the N,O, and S-alkylations of [(11)C]methyl iodide/[(11)C]methyl triflate and analogues of [(11)C]methyl iodide and their applications for making carbon-11 tracers; we then address recent advances in exploring a transmetallic complex mediated [(11)C]carbonyl reaction for oncologic targets.
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Division of Radiological Sciences, Washington University School of Medicine, Campus Box 8225, 510 S. Kingshighway Blvd., St. Louis, MO 63110, USA. uz@mir.wustl.edu
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D002250:Carbon Radioisotopes; D006801:Humans; D015336:Molecular Probe Techniques; D009369:Neoplasms / Q000175:diagnosis*; D049268:Positron-Emission Tomography; D011854:Radiochemistry; D019275:Radiopharmaceuticals
D002250:Carbon Radioisotopes; D019275:Radiopharmaceuticals