Correlação entre 99mTc-TRODAT-1 SPECT e 18F-FDOPA PET em pacientes com doença de Parkinson: Um estudo piloto

Objective: To determine whether technetium-99m-labeled tropane derivative single-photon emission computed tomography (99mTc-TRODAT-1 SPECT) provides results comparable to those of the less widely available, less accessible tool fluorine-18-labeled fluorodopa positron-emission tomography (18F-FDOPA PET) in the setting of a movement disorders clinic. Materials and Methods: In this prospective pilot study, eight subjects with a clinical diagnosis of Parkinson’s disease were randomly selected from among patients under treatment at a movement disorders clinic and submitted to99mTc-TRODAT-1 SPECT and18F-FDOPA PET. The results were read by two experienced observers, and a semiquantitative analysis was performed. Results: The visual and semiquantitative analyses were concordant for all studies, showing that radiotracer uptake in the contralateral striatum on the most affected side was lower when99mTc-TRODAT-1 SPECT was employed. The semiquantitative analysis demonstrated a significant correlation between18F-FDOPA PET and99mTc-TRODAT-1 SPECT (r = 0.73; p < 0.01). Conclusion: It appears that99mTc-TRODAT-1 SPECT is a valid option for the study of dopaminergic function in a clinical setting.Objetivo: Determinar se a 99mTc-TRODAT-1 SPECT fornece resultados comparáveis aos da 18F-FDOPA PET, ferramenta menos acessível e menos amplamente disponível, no contexto de uma clínica de distúrbios do movimento. Materiais e Métodos: Neste estudo prospectivo, oito indivíduos com diagnóstico clínico de doença de Parkinson foram selecionados aleatoriamente entre pacientes em tratamento em uma clínica de distúrbios do movimento e submetidos a 99mTc-TRODAT-1 SPECT e 18F-FDOPA PET. Os resultados foram lidos por dois observadores experientes e uma análise semiquantitativa foi realizada. Resultados: As análises visual e semiquantitativa foram concordantes para todos os estudos, mostrando que a captação do radiotraçador no estriado contralateral do lado mais afetado foi menor quando a 99mTc-TRODAT-1 SPECT foi empregada. A análise semiquantitativa demonstrou uma correlação significativa entre 18F-FDOPA PET e 99mTc-TRODAT-1 SPECT (r = 0,73; p < 0,01). Conclusão: A 99mTc-TRODAT-1 SPECT parece ser uma opção válida para o estudo da função dopaminérgica em um ambiente clínico.Fil: Arena, Julieta E.. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; ArgentinaFil: Urrutia, Leandro. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; ArgentinaFil: Falasco, Germán Alfredo. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; ArgentinaFil: Ponce de Leon, Magdalena. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; ArgentinaFil: Vazquez, Silvia. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; ArgentinaFil: Rossi, Malco Damian. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Merello, Marcelo Jorge. Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia. Instituto de Neurociencias - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Neurociencias; Argentina. Pontificia Universidad Católica Argentina "Santa María de los Buenos Aires"; Argentin

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements