A comparative study on the quality of in vivo labeled red blood cell radionuclide ventriculography images employing different freeze-dried reagents.

Radionuclide ventriculography or Multi Gated Acquisition (MUGA) employing [ 99m Tc]Technetium red blood cell (RBC) labeling is considered the gold standard for cardiotoxicity assessments in cancer patients undergoing chemotherapy. This in-vivo RBC labeling technique involves the reduction of [ 99m Tc]Technetium by the stannous chloride present in freeze-dried reagent kits, with the pyrophosphate kit (PYP) being the most employed for this purpose. The literature, however, describes diethylenetriaminepentaacetic acid (DTPA) as an alternative to PYP, although a lack of comparative data from MUGA images between both reagents is noted. A retrospective cross-sectional observational study was conducted at the Brazilian National Cancer Institute Nuclear Medicine Service concerning 80 randomized MUGA images, 20 obtained employing DTPA between 2020 and 2023 and 60 obtained employing PYP between 2017 and 2020, applying the mean count per pixel (ct/pixel) and heart background (C/F) ratios as quality image indicators. Although the heart ct/pixel ratio was statistically lower in the DTPA images compared with PYP ( P  = 0.02), the C/F ratio was statistically similar when comparing both radiopharmaceuticals ( P  = 0.697). A semi-quantitative analysis of MUGA images obtained with DTPA and PYP indicates similar image quality, supporting the use of DTPA as an alternative to PYP without compromising diagnostic interpretations.

Radioiodine therapy during the COVID-19 pandemic in a public reference hospital in Brazil: an experience report.

COVID-2019 has resulted in an emerging respiratory infection that has spread as a pandemic since January 2020. Nuclear Medicine Services and its workers experienced a dramatic change in their clinical routine. They were required to adjust protocols for this new health condition. Regarding radioiodine therapy (RIT), initial orientations were to postpone treatments. In Brazil, National Nuclear Energy Commission prepared guidelines. It authorized RIT to employ activities over 1850 MBq in an outpatient setting on an exceptional basis. This study reports the RIT experience of a Brazilian hospital during the COVID-19 pandemic, intending to evaluate the applicability of outpatient treatment employing over 1850 MBq of I-131 on a large scale. During referred period, 106 patients at our service had an indication for RIT, of which 58 agreed to participate in the research and provided informed consent. Majority of patients did not meet the minimum requirements for outpatient treatment using doses > 1850 MBq.

Development and biological studies of ¹77Lu-DOTA-rituximab for the treatment of Non-Hodgkin's lymphoma.

The optimization of DOTA-NHS-ester conjugation to Rituximab using different Ab:DOTA molar ratios (1:10, 1:20, 1:50 and 1:100) was studied. High radiochemical yield, in vitro stability and immunoreactive fraction were obtained for the Rituximab conjugated at 1:50 molar ratio, resulting in the incorporation of an average number of 4.9 ± 1.1 DOTA per Rituximab molecule. Labeling with 177Lu was performed in high specific activity with great in vitro stability. Biodistribution in healthy and xenographed mice showed tumor uptake and high in vivo stability as evidenced by low uptake in bone. The properties of 177Lu-DOTA-Rituximab prepared from DOTA-NHS-ester suggest the potential for the application of the 177Lu-labeled antibody in preliminary clinical studies.

Evaluation and comparison of a new DOTA and DTPA-bombesin agonist in vitro and in vivo in low and high GRPR expressing prostate and breast tumor models.

We evaluated and compared a new bombesin analog [Tyr-Gly5, Nle(14)]-BBN(6-14) conjugated to DOTA or DTPA and radiolabeled with In-111 in low and high GRPR expressing tumor models. Both peptides were radiolabeled with high radiochemical purity and specific activity. In vitro assays on T-47D, LNCaP and PC-3 cells showed that the affinity of peptides is similar and a higher binding and internalization of DOTA-peptide to PC-3 cells was observed. Both peptides could target PC-3 and LNCaP tumors in vivo and both tumor types could be visualized by microSPECT/CT.