177 Lu-DOTATATE peptide receptor radionuclide therapy (PRRT) alone has lesser potential in the clinical setting of neuroendocrine tumor (NET) with large bulky disease and nonhomogeneous somatostatin receptors (SSTR) distribution, owing to lower energy (Eβmax 0.497 MeV) and a shorter particle penetration range (maximum 2–4 mm) of 177 Lu. In large bulky NETs, 90 Yttrium ( 90 Y) has the theoretical advantages because of a longer beta particle penetration range (a maximum soft tissue penetration of 11 mm). Therefore, a combination of 177 Lu and 90 Y is a theoretically sound concept that can result in better response in metastatic NET with large-bulky lesion and non-homogeneous SSTR distribution. The aim of the study was to determine the feasibility of combining 90 Y-DOTATATE with 177 Lu-DOTATATE PRRT as sequential duo-PRRT in metastatic NET with (≥5 cm) including the post 90 Y-DOTATATE-PRRT imaging and also to determine early toxicity of the duo-PRRT approach. A total of 9 patients received combination of 177 Lu-DOTATATE with 90 Y-DOTATATE (indigenously prepared and approved) through sequential duo-PRRT approach. These 9 NET patients were included and analyzed in this study. All 9 patients had undergone post-PRRT 90 Y-DOTATATE imaging, including a whole-body planar bremsstrahlung imaging followed by regional single-photon emission computed tomography (SPECT)-computed tomography (CT) imaging and also a regional positron emission tomography–computed tomography imaging. Grading of 90 Y-DOTATATE and 177 Lu-DOTATATE uptake was done on post-PRRT imaging by both modalities. The size of the lesions ranged from 5.5 cm to 16 cm with average size of 10 cm before sequential duo-PRRT was decided. Sequential duo-PRRT was administered because of stable, unresponsive disease following 177 Lu-DOTATATE in 5 patients (55.6%), progressive disease after 177 Lu-DOTATATE in 2 patients (22.2%), and with neoadjuvant intent in 2 patients (22.2%). The total cumulative dose of 177 Lu-DOTATATE before duo-pRRT ranged from 11.84 GBq to 37 GBq per patient and average administered dose of 27.21 GBq per patient in this study. Out of 9 patients, 8 patients received single cycle of 90 Y-DOTATATE (ranging from 2.66 GBq to 3.4 GBq per patient with average administered dose of 3.12 GBq per patient). One patient received two cycles of 90 Y-DOTATATE (total dose of 6.2 GBq). Out of 9 patients, 8 patients showed excellent tracer concentration in lesions on post-PRRT 90 Y-DOTATATE imaging and the remaining 1 patient showed fairly adequate 90 Y-DOTATATE tracer uptake in lesion on visual anal...

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Pharmaceutical grade 3 0 -deoxy-3 0 -[ 18 F]fluorothymidine [ 18 F]FLT was synthesized using 3-N-Boc-5 0 -O-dimethoxytrityl-3 0 -O-nosyl-thymidine (BOC-Nosyl) precursor, in the general purpose TRACERlab FX modules. Purification of [ 18 F]FLT, via solid phase extraction (SPE) after radiosynthesis, using a combination of different SPE cartridges, yielded satisfactory results, with radiochemical and chemical purity >99%. While the non-decay corrected radiochemical yield (RCY) with 20 mg (24 μmole) of BOC-Nosyl precursor was found to be 6.80 ± 0.16%, the decay corrected radiochemical yield (RCY) was 9.95 ± 0.24%. Residual acetone, acetonitrile, and ethanol levels were found to be 22.97

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The efficacy of 177Lu-DOTATATE in large neuroendocrine tumors (NETs) is reduced because of the lower energy (Eβmax 0.497 MeV) and shorter range of 177Lu. The pure β-emitter 90Y with its longer β range is more effective in larger tumors. This should be balanced with the greater risk of 90Y-DOTATATE–related nephrotoxicity. Sequential duo–peptide receptor radionuclide therapy may result in a better response with minimal adverse effects in large-volume heterogeneous NETs. A 56-year-old man with large rectal NET liver metastases, treated with 90Y-DOTATATE and 177Lu-DOTATATE and sequential duo–peptide receptor radionuclide therapy, presented with post-90Y-DOTATATE bremsstrahlung and PET/CT in comparison with 68Ga-DOTATATE PET/CT and 177Lu-DOTATATE scans.

A bacterial endotoxin test (BET) is required to detect or quantify bacterial endotoxin that may be present in radiopharmaceutical preparations. The test uses Limulus amebocyte lysate, which, in the presence of bacterial endotoxin and divalent calcium ions, causes the formation of a coagulin gel. 99m Tc-labeled radiopharmaceuticals have chelating ligands such as diethylene triamine pentaacetic acid (DTPA), ethylene dicysteine (EC), L,L-ethyl cysteinate dimer (ECD), N- [2,4,6-trimethyl-3 bromoacetanilid] iminodiacetic acid (mebrofenin), dimercapto succinic acid-III (DMSA-III), dimercapto succinic acid-V (DMSA-V), and several others, which form a coordination complex with Na-99m Tc-O 4 in the presence of reducing agents. During BET by the gel-clot method, the free sulfhydryl (-SH) and carboxyl (-COOH) in some of the chelating agents in the final 99m Tclabeled radiopharmaceuticals decrease the free divalent calcium ion concentration, which in turn inhibits coagulin gel formation. This study was designed using the premise that addition of calcium chloride solution to the reaction mixture would nullify this effect. Methods: We present here the data obtained from BET assay analysis of 99m Tc-labeled radiopharmaceuticals and the cold kits from which they are made (EC, ECD, methoxyisobutylisonitrile, DTPA, mebrofenin, methylene diphosphonic acid [MDP], DMSA-III, and DMSA-V) using 2 different dilutions, maximum valid dilution (MVD) and half maximum valid dilution (MVD/2), with and without the addition of calcium chloride at a final concentration of 300 μM. Results: It was observed that at MVD and MVD/2 all of the 99m Tc-labeled kits exhibited interference in coagulin gel formation with the exception of 99m Tcmethoxyisobutylisonitrile, 99m Tc-MDP, 99m Tc-mebrofenin, and 99m Tc-ECD. However, only the cold kits of methoxyisobutylisonitrile and MDP did not show inhibition. An addition of calcium chloride solution nullified this interference at both MVD and MVD/2 in all of the 99m Tclabeled radiopharmaceuticals in which interference was observed. Conclusion: In practice, Limulus amoebocyte lysate testing is not a method of choice for 99m Tc-labeled radiopharmaceuticals because these radiopharmaceuticals exhibit interference. However, our study proves the hypothesis that the addition of calcium chloride can circumvent this problem. The addition of calcium chloride provides an enhanced biologic quality control testing option for the final formulation of 99m Tc-labeled radiopharmaceuticals at the hospital radiopharmacy end. In the centralized radiopharmacy laboratories of hospitals, different generator-based radiopharmaceuticals such as 99m 68 Ga-, and 90 Y-labeled molecules are being used for various diagnostic and therapeutic purposes. 99m Tclabeled radiopharmaceuticals have wider applications in SPECT and planar imaging with g cameras because of their short half-life (6.03 h) and pure g emission (140 keV). It is mandatory for hospital radiopharmacies to monitor the bacterial endotoxin levels of a 99m Tc-labeled radiopharmac...