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With regard to high reactivity and chemoselectivity of HYNIC towards carbonyl of acyclic form of 18 FDG and its stable complexes with 99m Tc, in this study, LIKKPF as the model peptide was conjugated with HYNIC and labelled with 99m Tc (RCP [90 %) and 18 FDG for the first time. The RCP of [70 % was achieved for labelling with 18 FDG, in the presence of glucose (50-250 lg/mL). Our results showed the high potential of HYNIC conjugated peptides for labelling with 99m Tc and 18 FDG as 18 Ffluorinated prosthetic group, to be clinically accepted for the radiolabelling of peptides.Keywords HYNIC Á Hydrazone bond Á 18 FDG Á 18 Ffluorinated prosthetic group Á 99m TcPositron emission tomography SPECT Single photon emission computed tomography HPLC High performance liquid chromatography TLC

Optimal performance of diagnostic tests and correct interpretation depend on multiple factors, one of which is proper radiopharmaceutical preparation. Unwanted impurities result in altered distribution of radiopharmaceuticals and then poor-quality or uninterpretable studies. Therefore, following the reconstitution steps according to standard and validated protocols by the technologist is mandatory. Here, we present 2 cases with unexpected and less recognized distribution of Tc-methylene diphosphonate on bone scintigraphy.

Background: Early detection of apoptosis is very important for therapy and follow-up treatment in various pathologic conditions. Annexin V interacts strongly and specifically with phosphatidylserine, specific biomarkers of apoptosis with some limitations. Small peptides are suitable alternatives to annexin V. A reliable and noninvasive in vivo technique for the detection of apoptosis is in great demand. Based on our previous studies, three new peptide analogs of LIKKPF (Leu-Ile-Lys-Lys-Pro-Phe) as apoptosis imaging agents were developed. Materials and Methods: Aoa-LIKKP-Cl-F, Aoe-LIKKP-Pyr-F, and Aoe-LIKKP-Nap-F were synthesized, functionalized with aminooxy, and radiolabeled with 18 F-FDG. Their biologic properties were evaluated in vitro using apoptotic Jurkat cells. 18 F-FDG-Aoe-LIKKP-Pyr-F peptide was injected into normal and apoptotic mice models for biodistribution and in vivo positron emission tomography/computed tomography imaging studies. Results: 18 F-FDG-Aoe-LIKKP-Pyr-F peptide showed higher affinity for apoptotic cells. The localization of peptide in apoptotic liver mice was confirmed in biodistribution and imaging studies. Conclusion: The results showed that Aoe-LIKKP-Pyr-F peptide is an auspicious agent for molecular imaging of apoptosis.