ALEXANDRE TELES GARCEZ
Projetos de Pesquisa
Unidades Organizacionais
Instituto do Câncer do Estado de São Paulo, Hospital das Clínicas, Faculdade de Medicina
LIM/43 - Laboratório de Medicina Nuclear, Hospital das Clínicas, Faculdade de Medicina
LIM/43 - Laboratório de Medicina Nuclear, Hospital das Clínicas, Faculdade de Medicina
6 resultados
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- Brain PET amyloid and neurodegeneration biomarkers in the context of the 2018 NIA-AA research framework: an individual approach exploring clinical-biomarker mismatches and sociodemographic parameters (vol 45, pg 616, 2020)(2020) COUTINHO, Artur Martins; BUSATTO, Geraldo F.; PORTO, Fabio Henrique de Gobbi; FARIA, Daniele de Paula; ONO, Carla Rachel; GARCEZ, Alexandre Teles; SQUARZONI, Paula; DURAN, Fabio Luiz de Souza; OLIVEIRA, Maira Okada de; TRES, Eduardo Sturzeneker; BRUCKI, Sonia Maria Dozzi; FORLENZA, Orestes Vicente; NITRINI, Ricardo; BUCHPIGUEL, Carlos Alberto
- Evaluation of GX1 and RGD-GX1 peptides as new radiotracers for angiogenesis evaluation in experimental glioma models(2016) OLIVEIRA, Erica Aparecida de; FAINTUCH, Bluma Linkowski; TARGINO, Roselaine Campos; MORO, Ana Maria; MARTINEZ, Raquel Chacon Ruiz; PAGANO, Rosana Lima; FONOFF, Erich Talamoni; CARNEIRO, Camila de Godoi; GARCEZ, Alexandre Teles; FARIA, Daniele de Paula; BUCHPIGUEL, Carlos AlbertoGliomas are the most common type among all central nervous system tumors. The aggressiveness of gliomas is correlated with the level of angiogenesis and is often associated with prognosis. The aim of this study is to evaluate the novel GX1 peptide and the heterodimer RGD-GX1 radiolabeled with technetium-99m, for angiogenesis detection in glioma models. Radiolabeling and radiochemical controls were assessed for both radioconjugates. In vitro binding studies in glioma tumor cells were performed, as well as biodistribution in SCID mice bearing tumor cells, in order to evaluate the biological behavior and tumor uptake of the radiocomplexes. Blocking and imaging studies were also conducted. MicroSPECT/CT images were acquired in animals with experimentally implanted intracranial tumor. Open field activity was performed to evaluate behavior, as well as perfusion and histology analysis. The radiochemical purity of both radiotracers was greater than 96 %. In vitro binding studies revealed rather similar binding profi le for each molecule. The highest binding was for RGD-GX1 peptide at 120 min in U87MG cells (1.14 +/- A 0.35 %). Tumor uptake was also favorable for RGD-GX1 peptide in U87MG cells, reaching 2.96 +/- A 0.70 % at 1 h p.i. with 47 % of blocking. Imaging studies also indicated better visualization for RGD-GX1 peptide in U87MG cells. Behavior evaluation pointed brain damage and histology studies confirmed actual tumor in the uptake site. The results with the angiogenesis seeking molecule Tc-99m-HYNIC-E-[c(RGDfk)-c(GX1)] were successful, and better than with Tc-99m-HYNIC-PEG(4)-c(GX1). Future studies targeting angiogenesis in other glioma and nonglioma tumor models are recommended.
- SUV Normalized by Skeletal Volume on F-18-Fluoride PET/CT Studies(2016) CARVALHO, Giovanna; MARIN, Jose Flavio Gomes; GARCEZ, Alexandre Teles; DUARTE, Paulo Schiavom; SAPIENZA, Marcelo Tatit; BUCHPIGUEL, Carlos AlbertoObjective: To propose a technique for SUV normalization on F-18-fluoride PET/CT (F-18-NaF) studies based on skeletal volume and to compare the SUVs normalized by this technique with the ones normalized by body weight. Methods: SUVs were obtained in volumes of interest (VOIs) in proximal diaphyseal regions of the right humerus (HD) and right femur (FD) in 12 selected F-18-NaF studies. The 12 studies presented both regions considered normal by visual examination on PET and CT and were performed in patients presenting body weight below 50 kg (B50) or above 90 kg (A90) (6 patients in each group). The maximum SUVs were calculated in these 2 bone regions in both groups of patients using body weight (SUV BW) and skeletal volume (SUV SV) methodologies. The total skeletal volume for each patient was estimated based on whole skeletal VOIs automatically defined on the CT component of the PET/CT study. The maximum SUVs calculated using the 2 methodologies were compared. Results: The maximum SUVs BW were statistically higher in the group A90 in both regions, with a P < 0.001 and P < 0.008 for FD and HD, respectively. The maximum SUVs SV in the 2 regions were not statistically different between the groups B50 and A90, P values of 0.27 and 0.87 for FD and HD, respectively. Conclusions: The SUVs normalized by skeletal volume present similar results in groups of patients with extremes of body weight. Therefore, this methodology could be more adequate than the one normalized by body weight to semiquantitatively analyze F-18-NaF studies.
- In vivo imaging evidence of poor cognitive resilience to Alzheimer's disease pathology in subjects with very low cognitive reserve from a low-middle income environment(2020) BUSATTO, Geraldo F.; PORTO, Fabio Henrique de Gobbi; FARIA, Daniele de Paula; SQUARZONI, Paula; COUTINHO, Artur Martins; GARCEZ, Alexandre Teles; ROSA, Pedro Gomes Penteado; COSTA, Naomi Antunes da; CARVALHO, Cleudiana Lima; TORRALBO, Leticia; HERNANDES, Jullie Rosana de Almeida; ONO, Carla Rachel; BRUCKI, Sonia Maria Dozzi; NITRINI, Ricardo; BUCHPIGUEL, Carlos Alberto; DURAN, Fabio Luis Souza; FORLENZA, Orestes VicenteINTRODUCTION: Reduced cognitive reserve (CR) due to very low educational (VLE) levels may influence high dementia rates in low-middle income environments, leading to decreased cognitive resilience (RES) to Alzheimers disease (AD) pathology. However, in vivo findings in VLE groups confirming this prediction are lacking. METHODS: Cognitively impaired patients (with clinically defined AD dementia or amnestic mild cognitive impairment) and cognitively unimpaired older adults (n = 126) were recruited for a positron emission tomography (PET) and magnetic resonance imaging (MRI) investigation in Brazil, including 37 VLE individuals (<= 5 years of education). A CR score was generated combining educational attainment and vocabulary knowledge. RES indices to AD pathology were calculated using standardized residuals from linear regression models relating current cognitive performance (episodic memory or overall cognition) to amyloid beta (A beta) burden Pittsburgh compound-B ([11C]PiB-PET). RESULTS: A beta burden was lower in VLE relative to highly-educated subjects (controlling for age, sex, and Mini-Mental Status Exam [MMSE] scores) in the overall cognitively impaired sample, and in dementia subjects when the three clinically defined groups were evaluated separately. In bivariate regression analyses for the overall sample, the RES index based on a composite cognitive score was predicted by CR, socioeconomic status, and hippocampal volume (but not white matter hyperintensities or intracranial volume [ICV]); in the multivariate model, only CR retained significance (and similar results were obtained in the A beta-positive subsample). In the multivariate model for the overall sample using the RES index based on memory performance, CR, hippocampal volume, and ICV were significant predictors, whereas only CR retained significance in A beta-positive subjects. DISCUSSION: Lower CR consistently predicted less resilience to AD pathology in older adults from a low-middle income environment.
- Brain PET amyloid and neurodegeneration biomarkers in the context of the 2018 NIA-AA research framework: an individual approach exploring clinical-biomarker mismatches and sociodemographic parameters(2020) COUTINHO, Artur Martins; BUSATTO, Geraldo F.; PORTO, Fabio Henrique de Gobbi; FARIA, Daniele de Paula; ONO, Carla Rachel; GARCEZ, Alexandre Teles; SQUARZONI, Paula; DURAN, Fabio Luiz de Souza; OLIVEIRA, Maira Okada de; TRES, Eduardo Sturzeneker; BRUCKI, Sonia Maria Dozzi; FORLENZA, Orestes Vicente; NITRINI, Ricardo; BUCHPIGUEL, Carlos AlbertoPurpose [F-18]FDG-PET and [C-11]PIB-PET are validated as neurodegeneration and amyloid biomarkers of Alzheimer's disease (AD). We used a PET staging system based on the 2018 NIA-AA research framework to compare the proportion of amyloid positivity (A+) and hypometabolism ((N)+) in cases of mild probable AD, amnestic mild cognitive impairment (aMCI), and healthy controls, incorporating an additional classification of abnormal [F-18]FDG-PET patterns and investigating the co-occurrence of such with A+, exploring [F-18]FDG-PET to generate hypotheses in cases presenting with clinical-biomarker ""mismatches."" Methods Elderly individuals (N = 108) clinically classified as controls (N = 27), aMCI (N = 43) or mild probable AD (N = 38) were included. Authors assessed their A(N) profiles and classified [F-18]FDG-PET neurodegenerative patterns as typical or non-typical of AD, performing re-assessments of images whenever clinical classification was in disagreement with the PET staging (clinical-biomarker ""mismatches""). We also investigated associations between ""mismatches"" and sociodemographic and educational characteristics. Results AD presented with higher rates of A+ and (N)+. There was also a higher proportion of A+ and (N)+ individuals in the aMCI group in comparison to controls, however without statistical significance regarding the A staging. There was a significant association between amyloid positivity and AD (N)+ hypometabolic patterns typical of AD. Non-AD (N)+ hypometabolism was seen in all A- (N)+ cases in the mild probable AD and control groups and [F-18]FDG-PET patterns classified such individuals as ""SNAP"" and one as probable frontotemporal lobar degeneration. All A- (N)- cases in the probable AD group had less than 4 years of formal education and lower socioeconomic status (SES). Conclusion The PET-based staging system unveiled significant A(N) differences between AD and the other groups, whereas aMCI and controls had different (N) staging, explaining the cognitive impairment in aMCI. [F-18]FDG-PET could be used beyond simple (N) staging, since it provided alternative hypotheses to cases with clinical-biomarker ""mismatches."" An AD hypometabolic pattern correlated with amyloid positivity. Low education and SES were related to dementia in the absence of biomarker changes.
- Dose calibrator linearity test: 99mTc versus 18F radioisotopes(2015) WILLEGAIGNON, José; SAPIENZA, Marcelo Tatit; COURA-FILHO, George Barberio; GARCEZ, Alexandre Teles; ALVES, Carlos Eduardo Gonzalez Ribeiro; CARDONA, Marissa Anabel Rivera; GUTTERRES, Ricardo Fraga; BUCHPIGUEL, Carlos AlbertoObjective: The present study was aimed at evaluating the viability of replacing 18F with 99mTc in dose calibrator linearity testing. Materials and Methods: The test was performed with sources of 99mTc (62 GBq) and 18F (12 GBq) whose activities were measured up to values lower than 1 MBq. Ratios and deviations between experimental and theoretical 99mTc and 18F sources activities were calculated and subsequently compared. Results: Mean deviations between experimental and theoretical 99mTc and 18F sources activities were 0.56 (± 1.79)% and 0.92 (± 1.19)%, respectively. The mean ratio between activities indicated by the device for the 99mTc source as measured with the equipment pre-calibrated to measure 99mTc and 18F was 3.42 (± 0.06), and for the 18F source this ratio was 3.39 (± 0.05), values considered constant over the measurement time. Conclusion: The results of the linearity test using 99mTc were compatible with those obtained with the 18F source, indicating the viability of utilizing both radioisotopes in dose calibrator linearity testing. Such information in association with the high potential of radiation exposure and costs involved in 18F acquisition suggest 99mTc as the element of choice to perform dose calibrator linearity tests in centers that use 18F, without any detriment to the procedure as well as to the quality of the nuclear medicine service.