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18F-FDG is a most popular radiopharmaceutical for tumor diagnosis in the world. In addition, 11C-methionine, 18F-FLT and 11C-choline have been used to compensate for drawbacks of 18F-FDG. Now, novel radiopharmaceuticals are required to estimate or predict therapeutic efficacy because we have many strategies to treat tumors. Radiotherapy which damage DNA by producing free radicals is commonly used to treat various types of tumors. Hypoxia is closely associated with resistance to chemo- and/or radiotherapy and is a common feature of solid tumors. Recently, understanding of tumor hypoxia in oncology has led to development of radiopharmaceuticals for hypoxia imaging. This review provides an overview of PET radiopharmaceuticals for hypoxia imaging and 18F-FBPA which is used for boron neutron capture therapy.

The structure of tumor vasculature is crucial for the nanocarrier-mediated chemotherapy. Recently, transforming growth factor-β (TGF-β) inhibitor was reported to increase the tumor accumulation of nanocarriers by changing the structure of tumor vasculature. To identify the parameters of tumor vasculature function following TGF-β inhibitor (A-83-01) treatment, dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) was performed using Gd-DTPA and its liposomal formulation (Gd-L) as contrast agents. Observation of tumor MR image before, during, and after injection of contrast agent could calculate the parameters of vascular function, such as volume transfer constant between blood plasma and extracellular space (K(trans)) and fractional plasma volume (v(p)). A-83-01 treatment significantly increased these parameters within 24 h that was positively related to pericyte coverage and tumor cell proliferation. Furthermore, apparent diffusion coefficient (ADC) determined by diffusion-weighed imaging was decreased by A-83-01 treatment, suggesting the decrease of tumor interstitial fluid pressure. Vascular function of the tumor improved by A-83-01 treatment well assessed on post-Gd-L-enhanced MR images, which predicted delivery of liposomal drug to the tumor. These findings suggest that DCE-MRI and, in particular, K(trans) and v(p) quantitation, provide important additional information about tumor vasculature by A-83-01 treatment.

Recent plausibility of generator produced 62Cu, a positron emitter is attracting the interest of those working in the development of bifunctional radiopharmaceuticals (BR). In our development of bifunctional radiopharmaceuticals containing a neutral dithiosemicarbazone (DTS) metal chelate, tertiary (p-DPA-DTS) and quaternary (p-TPA-DTS) amino DTS derivatives were synthesized. As for the basic understanding of their divalent metal (Cu2+, Ni2+, Zn2+) complex formation and stability, spectrophotometrical studies were carried out, comparatively with KTS. Upon assessment of preferential behavior of Cu chelate, the radiolabeled 64Cu-DTS derivative chelates were tested in mice, and potential use with 62Cu in positron nuclear medicine is discussed.