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Background: The aim of this brief communication is to highlight the potential bacteriological risk linked to the processes control of radiopharmaceutical preparations made in a radiopharmacy laboratory. Survival rate of Pseudomonas aeruginosa (ATCC: 27853) or Staphylococcus aureus (ATCC: 25923) or Staphylococcus epidermidis (ATCC: 1228) in multidose technetium-99 m solution was studied. Results: Depending on the nature and level of contamination by pathogenic bacteria, the lethal effect of radioactivity is not systematically observed. We found that P. aeruginosa was indeed affected by radioactivity. However, this was not the case for S. epidermidis, as the quantity of bacteria found in both solutions (radioactive and non-radioactive) was rapidly reduced, probably due to a lack of nutrients. Finally, the example of S. aureus is an intermediate case where we observed that high radioactivity affected the bacteria, as did the absence of nutrients in the reaction medium. The results were discussed in the light of current practices on the sterility test method, which recommends waiting for radioactivity to decay before carrying out the sterility test. Conclusion: In terms of patient safety, the results run counter to current practice and the latest EANM recommendation of 2021 that radiopharmaceutical preparations should be decayed before sterility testing. [ABSTRACT FROM AUTHOR]

Background: Despite the development of positron emission tomography (PET), single photon emission computed tomography (SPECT) still accounts for around 80% of all examinations performed in nuclear medicine departments. The search for new radiotracers or chelating agents for Technetium-99m is therefore still ongoing. O-TRENSOX and O-TRENOX two synthetic siderophores would be good candidates for this purpose as they are hexadentate ligands based on the very versatile and efficient 8-hydroxyquinoline chelating subunit. First, the radiolabeling of O-TRENOX and O-TRENSOX with 99mTc was investigated. Different parameters such as the quantity of chelating agent, type of reducing agent, pH and temperature of the reaction mixture were adjusted in order to find the best radiolabeling conditions. Then an assessment of the partition coefficient by measuring the distribution of each radiosynthesized complex between octanol and phosphate-buffered saline was realized. The complex's charge was evaluated on three different celluloses (neutral, negatively charged P81 and positively charged DE81), and finally in vivo studies with biodistribution and SPECT imaging of [99mTc]Tc-O-TRENOX and [99mTc]Tc-O-TRENSOX were performed. Results: The radiolabeling studies showed a rapid and efficient complexation of 99mTc with both chelating agents. Using tin pyrophosphate as the reducing agent and a minimum of 100 nmol of ligand, we obtained the [99mTc]Tc-O-TRENOX complex with a radiochemical purity of more than 98% and the [99mTc]Tc-O-TRENSOX complex with one above 97% at room temperature within 5 min. [99mTc]Tc-O-TRENOX complex was lipophilic and neutral, leading to a hepatobiliary elimination in mice. On the contrary, the [99mTc]Tc-O-TRENSOX complex was found to be hydrophilic and negatively charged. This was confirmed by a predominantly renal elimination in mice. Conclusions: These encouraging results allow us to consider the O-TRENOX/99mTc and O-TRENSOX/99mTc complexes as serious candidates for SPECT imaging chelators. This study should be continued by conjugating these tris-oxine ligands to peptides or antibodies and comparing them with the other bifunctional agents used with Tc. [ABSTRACT FROM AUTHOR]

Background: To assess whether whole-body (WB) bone SPECT/CT provides additional diagnostic information over [18F]-FCH PET/CT for the detection of bone metastases in the setting of prostate cancer biochemical recurrence (PC-BR)., Methods: Patients referred for a PC-BR and whom benefited from a WB bone SPECT/CT and FCH PET/CT were retrospectively included. Tests were classified as positive, equivocal, or negative for bone metastases. A best valuable comparator (BVC) strategy including imaging and follow-up data was used to determine the metastatic status in the absence of systematic histological evaluation., Results: Between January 2011 and November 2017, 115 consecutive patients with a PC-BR were evaluated. According to the BVC, 30 patients had bone metastases and 85 patients did not present with bone lesions. The sensitivity, specificity, positive and negative predictive values were respectively 86.7% [69.3-96.2], 98.8% [93.6-100.0], 96.3% [78.7-99.5], and 95.5% [89.4-98.1] for WB bone SPECT/CT and 93.3% [77.9-99.2], 100.0% [95.8-100.0], 100.0 and 97.7% [91.8-99.4] for FCH PET/CT. There was no significant difference in diagnostic accuracy of bone metastases between WB Bone SPECT/CT (AUC 0.824 [0.74-0.90]) and FCH PET/CT (AUC 0.829 [0.75-0.90], p = 0.41)., Conclusion: Despite good performances for the diagnosis of bone metastases in PC-BR, WB bone SPECT/CT does not provide additive diagnostic information over concomitant FCH PET/CT.