Browsing by Author "Metello, Luis F."
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- 99mTc-Technetium Shortage: old problems asking for new solutionsPublication . Metello, Luis F.Technetium 99-metastable (99mTc) is the most important radionuclide, responsible for more than 80% of applications in nuclear medicine, with more than 40 million procedures being performed each year, worldwide, in all major clinical fields. It decays with a half-life of 6.01 hours by isomeric tran sition to 99gTc, thereby emitting 140 keV gamma photons. This energy almost ideally meets the maximum sensitivity of single photon emission computed tomography (SPECT) cam era systems. In addition, the rich complex chemistry of Techne tium allows the incorporation of the radioisotope into a wide variety of ligands stabilizing the radionuclide at different oxida tion states. Thus, since the early 60s, hundreds of radiopharma ceuticals labeled with 99mTc have been developed, and some have gained significant market success. However, the main reason for the special role of Technetium in SPECT is probably the cost effectiveness and the on-demand worldwide availability of the isotope through the 99Mo/99mTc generator systems.
- Optimization and validation of [13N]-NH3 production for clinical studies of positron emission tomography in the evaluation of myocardial perfusionPublication . Serra, Cristina; Neves, Angela; Abrunhosa, Antero J.; Metello, Luis F.The present work aims to validate the [ 13 N]-NH 3 production for human studies of myocardial perfusion using a cyclotron from a Portuguese public institution and an automatic synthesis module. According to specifications of European Pharmacopeia (Ph. Eur.) 8.2., 3 consecutives batches were evaluated for this purpose. Results showed a clear and colorless product and pH values between 4,5 e 8,5. The chemical purity was confirmed by the colorimetric test and the samples were identified as [ 13 N]-NH 3 , by ionic chromatography, gamma ray spectroscopy and half-life determination. Radiochemical and radionuclidic purity were confirmed, corresponding a minimum of 99% of total radioactivity to [ 13 N] and a percentage of impurities less than 1%, 2 hours after the end of synthesis. Tests for sterility and for presence of bacterial endotoxins were also performed.
- Optimization of OSEM parameters in myocardial perfusion imaging reconstruction as a function of body mass index: a clinical approachPublication . Barros, Pietro Paolo de; Metello, Luis F.; Camozzato, Tatiane Sabriela Cagol; Vieira, DomingosObjective The present study is aimed at contributing to identify the most appropriate OSEM parameters to generate myocardial perfusion imaging reconstructions with the best diagnostic quality, correlating them with patients’ body mass index. Materials and Methods The present study included 28 adult patients submitted to myocardial perfusion imaging in a public hospital. The OSEM method was utilized in the images reconstruction with six different combinations of iterations and subsets numbers. The images were analyzed by nuclear cardiology specialists taking their diagnostic value into consideration and indicating the most appropriate images in terms of diagnostic quality. Results An overall scoring analysis demonstrated that the combination of four iterations and four subsets has generated the most appropriate images in terms of diagnostic quality for all the classes of body mass index; however, the role played by the combination of six iterations and four subsets is highlighted in relation to the higher body mass index classes. Conclusion The use of optimized parameters seems to play a relevant role in the generation of images with better diagnostic quality, ensuring the diagnosis and consequential appropriate and effective treatment for the patient.