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Lipophilic cations such as phosphonium salts can accumulate in mitochondria of heart in response to the negative inner-transmembrane potentials. Two phosphonium salts [(18)F]FMBTP and [(18)F]mFMBTP were prepared and evaluated as potential myocardial perfusion imaging (MPI) agents in this study. The cations were radiolabeled via a simplified one-pot method starting from [(18)F]fluoride and followed by physicochemical property tests, in vitro cellular uptake assay, ex vivo mouse biodistribution, and in vivo rat microPET imaging. The total radiosynthesis time was less than 60 min including HPLC purification. The [(18)F] labeled compounds were obtained in high radiolabeling yield (∼50%) and good radiochemical purity (>99%). Both compounds were electropositive, and their log P values at pH 7.4 were 1.16 ± 0.003 (n = 3) and 1.05 ± 0.01 (n = 3), respectively. Both [(18)F]FMBTP and [(18)F]mFMBTP had high heart uptake (25.24 ± 2.97% ID/g and 31.02 ± 0.33% ID/g at 5 min postinjection (p.i.)) in mice with good retention (28.99 ± 3.54% ID/g and 26.82 ± 3.46% ID/g at 120 min p.i.). From the PET images in rats, the cations exhibited high myocardium uptake and fast clearance from liver and small intestine to give high-contrast images across all time points. These phosphonium cations were radiosynthesized via a highly efficient one-pot procedure for potential MPI offering high heart accumulation and rapid nontarget clearance.

Poly(vinylbenzyl-O-b-D-galactopyranosyl-D-gluconamide) (PVLA) can be specifically internalized by hepatocytes via the asialoglycoprotein receptor. In this study, we synthesized and characterized galactose-carrying copolymers with hydrazinonicotinamide chains as bifunctional groups to radiolabel PVLA with 99m Tc for SPECT targeting specific hepatocytes. Methods:The copolymer was labeled with 99m Tc using tricine as a coligand. Then 99m Tc[P(VLA-co-VNI)](tricine) 2 was evaluated by in vivo metabolic stability and biodistribution in normal mice. SPECT was performed in normal New Zealand White rabbits and rabbits with liver cancer. Results: 99m Tc[P(VLA-co-VNI)](tricine) 2 was prepared in high labeling yield (.95%) and radiochemical purity (.99%), with good stability. The results of biodistribution in mice demonstrated that the liver uptake was 125.33 6 10.99 percentage injected dose per gram at 10 min after injection and could be blocked significantly by preinjecting free neogalactosylalbumin or P(VLA-co-VNI). SPECT images with high quality were obtained at 15, 30, 60, and 120 min after injection of the radiotracer. Significant radioactivity defect was observed in the liver cancer model. Conclusion: The bifunctional coupling agent hydrazinonicotinamide was introduced to PVLA via copolymerization and labeled with 99m Tc. The promising biologic properties of 99m Tc[P(VLA-co-VNI)](tricine) 2 afford potential applications for the assessment of hepatocyte function in the future.