ABSTRACT
Positron emission tomography (PET) and single photon emission computed tomography (SPECT) play important roles in the diagnosis and staging of cancer, as well as in the monitoring of tumor response to therapy. Positron and single photon-emitting radiotracers are also important tools in research including molecular imaging and gene therapy of cancer. This chapter describes the fundamental chemistry used in the preparation of small molecule SPECT radiopharmaceuticals. For radiolabeling, 99mTc is eluted from a commercial 99Mo/99mTc generator in saline as sodium pertechnetate (Na99mTcO4). In this form technetium is in the +7 oxidation state. Technetium-99m radiopharmaceuticals can be divided into two classes of compounds, “technetium essential” and “technetium tagged”. The structure of the desired radiohalogenated compound guides the method of radioiodination/radiobromination. Radioiodine or radiobromine is usually incorporated into the molecule at or near the end of the synthesis.
