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.

Health-related quality of life of thyroid cancer patients undergoing radioiodine therapy: a cohort real-world study in a reference public cancer hospital in Brazil.

PURPOSE: The purpose of this study was to access changes in health-related quality of life (HRQoL) caused by radioiodine therapy (RAI) in thyroid cancer patients. METHODS: Prospective cohort study at Brazilian National Cancer Institute with patients enrolled between March 2015 and June 2017. RAI was performed by administration of 1.11 to 9.25 GBq of Na131I. EORTC QLQ-C30 v3 and EORTC QLQ-H&N35 questionnaires were applied to determine HRQoL at baseline, 1 week and 3 months after RAI. HRQoL during follow-up was evaluated by calculation of score absolute changes in each domain. Descriptive analysis was performed by measures of central tendency and dispersion. Changes in HRQoL were evaluated by paired t-test. The association between social demographic and clinical data and HRQoL was assessed by univariate linear regression for significantly changed domains, and p < 0.05 was considered significant. RESULTS: An improvement on global HRQoL and social Function post-therapy (p = 0.002 and p < 0.001) and on role (p = 0.038), emotional (p < 0.001), and cognitive function (p = 0.016) during RAI were observed. Nausea and vomiting (p < 0,001), pain (p < 0.001), sensitivity problems (p < 0.001), problems with social contact (p < 0.001), dry mouth (p = 0.007), and sticky saliva (p = 0.001) increased during RAI. Females were more sensible to changes in nausea and vomiting, and patients < 55 years experienced higher changes in sense during RAI. CONCLUSIONS: Although RAI might affect HRQoL negatively, patients experienced an improvement on global HRQoL and symptoms reduction post-therapy.

Drug interaction with radiopharmaceuticals: effect on the labeling of red blood cells with technetium-99m and on the bioavailability of radiopharmaceuticals

The evidence that natural and synthetic drugs can affect radiolabeling or bioavailability of radiopharmaceuticals in setting of nuclear medicine clinic is already known. However, this drug interaction with radiopharmaceuticals (DIR) is not completely understood. Several authors have described the effect of drugs on the labeling of blood elements with technetium-99m (99mTc) and on the biodistribution of radiopharmaceuticals. When the DIR is known, if desirable or undesirable, the natural consequence is a correct diagnosis. However, when it is unknown, it is undesirable and the consequences are the possibility of misdiagnosis and/or the repetition of the examination with an increase of radiation dose to the patient. The possible explanation to the appearance of DIR are (a) radiopharmaceutical modification, (b) alteration of the labeling efficiency of the radiopharmaceutical, (c) modification of the target, (d) modification of no target and/or the (e) alteration of the binding of the radiopharmaceutical on the blood proteins. The effect of drugs on the labeling of blood elements with 99mTc might be explained by (i) a direct inhibition (chelating action) of the stannous and pertechnetate ions, (ii) damage induced in the plasma membrane, (iii) competition of the cited ions for the same binding sites, (iv) possible generation of reactive oxygen species that could oxidize the stannous ion and/or (v) direct oxidation of the stannous ion. In conclusion, the development of biological models to study the DIR is highly relevant

Effect of mitomycin-C on the bioavailability of the radiopharmaceutical (99m)technetium-phytic acid in mice: a model to evaluate the toxicological effect of a chemical drug.

The many desirable characteristics of technetium-99m ((99m)Tc) have stimulated the development of labelling techniques for different molecular and cellular structures. It is generally accepted that a variety of factors can alter the biodistribution of radiopharmaceuticals and one such factor is drug therapy. Because patients on chemotherapeutic treatment receive a radiopharmaceutical in a nuclear medicine procedure, we have studied in Balb/c mice the effect of mitomycin-C on the biodistribution of the radiopharmaceutical (99m)Tc-phytic acid ((99m)Tc-PHY) used in hepatic scintigraphy. Mitomycin-C is an antineoplastic agent obtained from Streptomyces caesptosus and is used on the treatment of disseminated adenocarcinoma of the stomach or pancreas. Three doses of mitomycin-C were administered via the ocular plexus into Balb/c mice. One hour after the last dose, (99m)Tc-PHY was administered and the animals were sacrificed. The organs were isolated, the radioactivity was determined in a well counter and the percentages of radioactivity in the organs were calculated. The results have shown that the percentage radioactivity has been increased in stomach, spleen, lung, thyroid and bone, decreased in pancreas and thymus and not altered in ovary, uterus, kidney, heart, liver and brain. The changes in the distribution of (99m)Tc-PHY may be the result of metabolic processes and/or therapeutic actions produced by the administration of mitomycin-C.

The effect of murine B16F10 melanoma on the biodistribution of 99mTc-MDP in male C57BL/6J mice.

The biodistribution of radiopharmaceuticals used in diagnostic imaging can be altered by a wide variety of factors. We studied the effect of murine B16F10 melanoma on the biodistribution in mice of 99mTechnetium-methylenediphosphonic acid (99mTc-MDP). Viable B16-F10 cell lines (1 x 10(5)) were inoculated subcutaneously in the dorsal region of 8-12 week-old male isogenic C57BV/6j mice. 14-16 days after inoculation, 99mTc-MDP was injected in the ocular plexus and after 0.5 hr the animals were rapidly sacrificed. The organs and tumor were isolated, the mass determined and the percentage per gram of injected activity (%ATI/g) calculated. The results shown that the %ATI/g:i/ has not been altered in inguinal lymph nodes, prostate, pancreas, testis, seminal vesicle, bladder, kidney, stomach, small intestine, spleen, thymus, heart, lung, brain and muscle; but ii/ significantly decreased in thyroid, bone, blood and liver. In conclusion, the B16F10 melanoma can alter the 99mTc-MDP uptakes in some organs.

Evaluation of the effect of mitomycin-C on the bioavailability of technetium-99m-labelled sodium pyrophosphate in mice.

We have reported that drugs alter the biodistribution of radiopharmaceuticals used in diagnostic imaging in nuclear medicine. Knowledge of such altered biodistribution is important in making diagnostic from scintigraphy. Mitomycin-C is used as component of many chemotherapeutic regimens to treat different tumors. The biological activities of mitomycin-C can be explained by its ability to inhibit deoxyribonucleic acid synthesis. Since patients on chemotherapeutic treatment can be submitted to nuclear medicine procedures, we studied the mitomycin-C effect on the bioavailability of the technetium-99m-labelled sodium pyrophosphate (9mTc-PYP) using an animal model. Mitomycin (0.45 mg) was administered by ocular plexus way Balb/c mice. One hour after the last dose, 99mTc-PYP (7.4 MBq) was administered and after 0.5 hr the animals (n = 15) were rapidly sacrificed. The organs were isolated, the radioactivity counted in a well counter and the percentage of radioactivity (%ATI) calculated. The results have shown that in the treated animals the %ATI has been decreased in spleen, thymus, heart and brain and increased in lung, liver and bone. The effect of this chemotherapeutic drug on the 99mTc-PYP biodistribution was statistically significant (Wilcoxon test, p < 0.05) and it could be explained by the metabolization or therapeutic action of mitomycin-C.

Criterios para el diagnostico de aspergilosis y candidosis sistemica / Criteria for the diagnosis of aspergillosis and systemic candidosis

Con objeto de ayudar al diagnóstico de aspergilosis y candidosis sistemíca, se estudiaron 253 casos de pacientes con afecciones respiratorias por medio de pruebas inmunológicas. Basados en los resultados, se sugiere el siguiente criterio para su diagnóstico: características clínicas del paciente, cultivos seriados positivos de muestras biológicas, histopatología sugestiva (presencia del hongo en tejido), pruebas inmunológicas seriadas con títulos elevados y resultados similares en precipitinas, aglutininas y reacción de fijación de complemento