a systematic review and meta-analysis

OKThere is significant evidence linking a 'reward deficiency syndrome' (RDS), comprising decreased availability of striatal dopamine D2-like receptors (DD2lR) and addiction-like behaviors underlying substance use disorders and obesity. Regarding obesity, a systematic review of the literature with a meta-analysis of such data is lacking. Following a systematic review of the literature, we performed random-effects meta-analyses to determine group differences in case-control studies comparing DD2lR between individuals with obesity and non-obese controls and prospective studies of pre- to post-bariatric surgery DD2lR changes. Cohen's d was used to measure effect size. Additionally, we explored factors potentially associated with group differences in DD2lR availability, such as obesity severity, using univariate meta-regression. In a meta-analysis including positron emission tomography (PET) and single-photon emission computed tomography (SPECT) studies, striatal DD2lR availability did not significantly differ between obesity and controls. However, in studies comprising patients with class III obesity or higher, group differences were significant, favoring lower DD2lR availability in the obesity group. This effect of obesity severity was corroborated by meta-regressions showing inverse associations between the body mass index (BMI) of the obesity group and DD2lR availability. Post-bariatric changes in DD2lR availability were not found, although a limited number of studies were included in this meta-analysis. These results support lower DD2lR in higher classes of obesity which is a more targeted population to explore unanswered questions regarding the RDS.publishersversionpublishe

Extraction, selection and comparison of features for an effective automated computer-aided diagnosis of Parkinson's disease based on [123I]FP-CIT SPECT images

Purpose This work aimed to assess the potential of a set of features extracted from [I-123] FP-CIT SPECT brain images to be used in the computer-aided "in vivo" confirmation of dopaminergic degeneration and therefore to assist clinical decision to diagnose Parkinson's disease.Methods Seven features were computed from each brain hemisphere: five standard features related to uptake ratios on the striatum and two features related to the estimated volume and length of the striatal region with normal uptake. The features were tested on a dataset of 652 [I-123] FP-CIT SPECT brain images from the Parkinson's Progression Markers Initiative. The discrimination capacities of each feature individually and groups of features were assessed using three different machine learning techniques: support vector machines (SVM), k-nearest neighbors and logistic regression.Results Cross-validation results based on SVM have shown that, individually, the features that generated the highest accuracies were the length of the striatal region (96.5%), the putaminal binding potential (95.4%) and the striatal binding potential (93.9%) with no statistically significant differences among them. The highest classification accuracy was obtained using all features simultaneously (accuracy 97.9%, sensitivity 98% and specificity 97.6%). Generally, slightly better results were obtained using the SVM with no statistically significant difference to the other classifiers for most of the features.Conclusions The length of the striatal region uptake is clinically useful and highly valuable to confirm dopaminergic degeneration "in vivo" as an aid to the diagnosis of Parkinson's disease. It compares fairly well to the standard uptake ratio-based features, reaching, at least, similar accuracies and is easier to obtain automatically. Thus, we propose its day to day clinical use, jointly with the uptake ratio-based features, in the computer-aided diagnosis of dopaminergic degeneration in Parkinson's disease

A robust computational solution for automated quantification of a specific binding ratio based on [123I]FP-CIT SPECT images

Aim The purpose of the current paper is to present a computational solution to accurately quantify a specific to a non-specific uptake ratio in [123I] FP-CIT single photon emission computed tomography (SPECT) images and simultaneously measure the spatial dimensions of the basal ganglia, also known as basal nuclei. A statistical analysis based on a reference dataset selected by the user is also automatically performed.Methods The quantification of the specific to non-specific uptake ratio here is based on regions of interest defined after the registration of the image under study with a template image. The computational solution was tested on a dataset of 38 [123I]FP-CIT SPECT images: 28 images were from patients with Parkinson's disease and the remainder from normal patients, and the results of the automated quantification were compared to the ones obtained by three well-known semi-automated quantification methods.Results The results revealed a high correlation coefficient between the developed automated method and the three semi-automated methods used for comparison (r ≥ 0.975). The solution also showed good robustness against different positions of the patient, as an almost perfect agreement between the specific to non-specific uptake ratio was found (ICC = 1.000). The mean processing time was around 6 seconds per study using a common notebook PC.Conclusions The solution developed can be useful for clinicians to evaluate [123I]FP-CIT SPECT images due to its accuracy, robustness and speed. Also, the comparison between case studies and the follow-up of patients can be done more accurately and proficiently since the intra- and inter-observer variability of the semi-automated calculation does not exist in automated solutions. The dimensions of the basal ganglia and their automatic comparison with the values of the population selected as reference are also important for professionals in this area

CORPORATE GOVERNANCE AND ECONOMIC PERFORMANCE: AN ANALYSIS OF PERFORMANCE INDICATORS AMONG THE THREE LEVELS OF BM&FBOVESPA’S DIFFERENTIATED MARKET

La gobernanza corporativa, surgida con la intención de resolver o disminuir los conflictos deagencia, parece tener el beneficio adicional de incrementar el valor de mercado de las empresas que lapractican en elevados niveles. Estudios empíricos realizados en Brasil, Estados Unidos y Europa han dejadoen evidencia los beneficios de rendimiento económico obtenido por las empresas con buenas prácticas degobernanza en relación a aquellas que no las adoptan. Tomando una línea alternativa – y complementar –de investigación, este estudio analiza la relación entre los diferentes niveles de gobernanza corporativa delas empresas y el aumento de su valor de mercado, o sea, examina si para niveles más elevados degobernanza hay mejor rendimiento económico. Fueron analizadas las 182 empresas del mercadodiferenciado de la BM&FBOVESPA, por ser las que presentan los niveles más elevados de gobernanzacorporativa, agrupadas en los tres diferentes segmentos de la lista – Nuevo Mercado, Nivel 2 y Nivel 1 – yrelacionadas con su valor de mercado. Los datos fueron analizados con base en la estadística descriptiva yanálisis inferencial, testes de media y análisis de variancia. Se han obtenido evidencias de que las empresaslistadas en los niveles más elevados del mercado diferenciado poseen mejor rendimiento económico, medidoen términos de variación media del valor de mercado.Corporate governance, which emerged in order to solve or mitigate the agency conflicts, seems to havethe additional benefit of increasing the market value of the companies that practice it in higher levels.Empirical research developed in Brazil, United States and Europe have shown the benefits in economicperformance achieved by companies with good governance practices in relation to those that do not adoptthem. By taking an alternative and complementary line of inquiry, this study analyzes the relationshipbetween different levels of corporate governance of companies and the increase in their market value, thatis, if the higher corporate governance level means the higher increase in economic development. Wereanalyzed all the 182 companies present in BM&FBOVESPA’s differentiated market, for they present thehigher levels of corporate governance, distributed in three levels – “New Market”, “Level 2”, and “Level 1”– relating them to their market value. Data were analyzed using descriptive statistics and inferentialanalysis, applying average testes and variance analysis. We found evidences that companies listed in thehigher level of differentiated market present a better economic performance, measured in terms of marketvalue’s average variation.A governança corporativa, surgida com o intuito de resolver ou diminuir os conflitosde agência, pareceter o benefício adicional de incrementar o valor de mercado das empresas que a praticam em níveis elevados.Estudos empíricos realizados no Brasil, Estados Unidos e Europa têm evidenciado os benefícios dodesempenho econômico obtidos pelas empresas com boas práticas de governança em relação àquelas que nãoas adotam. Tomando uma linha alternativa – e complementar – de investigação, este estudo analisa arelaçãoentre os diferentes níveis de governança corporativa das empresas e o aumento do seu valor de mercado, ouseja, examina se para níveis mais elevados de governança há melhor desempenho econômico. Foramanalisadastodas as 182 empresas do mercado diferenciado da BM&FBOVESPA, por serem as queapresentam os níveis mais elevados de governança corporativa, agrupadas nos três diferentes segmentos delistagem – Novo Mercado, Nível 2 e Nível 1 – e relacionadas com seu valor de mercado. Os dados foramanalisados com base na estatística descritiva e em análises inferenciais, testes de média e análise devariância. Foram obtidas evidências de que as empresas listadas nos níveis mais elevados do mercado diferenciado possuem melhor desempenho econômico, medido em termos de variação média do valor de mercado

Evaluation of the attenuation correction on myocardial perfusion imaging: a phantom study

Myocardial perfusion imaging (MPI) with single-photon emission computed tomography (SPECT) is important for risk stratification of coronary artery disease. MPI quantification obtained from available images may not be accurate due to several potential sources of error, being photon attenuation, especially in overweight patients, a significant problem. Attenuation maps derived from X-ray computed tomography (CT) may be used to correct for photon attenuation. The aim of this study was to evaluate the effects of non-attenuation correction (NAC) and attenuation correction (AC) in MPI SPECT imaging using anthropomorphic phantoms simulating patients with different attenuation profiles. Forty-nine SPECT and CT studies of Heart/Thorax phantoms with different attenuation layers were acquired. All SPECT imaging data were reconstructed with and without AC. Quantification of the myocardial signal (uptake) was performed in four regions of interest: septum, anterior wall, inferior wall, and apex. This was done both in NAC and AC SPECT images. A qualitative evaluation was performed by a nuclear medicine physician also in NAC and AC SPECT images. The results demonstrated, as expected, statistically lower counts when the thickness of the phantom attenuating material increased and attenuation correction was lacking. On the other hand, when attenuation correction was applied, there were no statistically significant count differences whatever the thickness of the phantom attenuating material. In the qualitative evaluation, the nuclear medicine physician observed small variations in the anterior wall uptake according to the various conditions under test. However, the changes were not statistically significant. In conclusion, there is no evidence that the effects of attenuation in overweight patients are not properly corrected when the MPI SPECT images are reconstructed with CT-based AC. In terms of qualitative visual assessment, there is no significant variation in the classification of myocardial walls uptake with and without AC when the evaluation is done by an experienced physician.info:eu-repo/semantics/publishedVersio

Brain [¹⁸F]Fluorodeoxyglucose Metabolism Assessment under Hypothyroidism and Recombinant Human Thyroid-Stimulating Hormone in Comparison with Thyroid Hormone Replacement in Patients Submitted to Total Thyroidectomy

Objective: To compare brain metabolism using [18F]fluorodeoxyglucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) in total thyroidectomy patients during hypothyroidism (levothyroxine withdrawal) or under recombinant human thyroid-stimulating hormone (rhTSH) against levothyroxine intake. Methods: A total of 12 patients were randomly divided into two groups. One group underwent the first [18F]FDG PET/CT brain scan after levothyroxine withdrawal (hypothyroidism condition) and repeated the scan 6 months later during regular levothyroxine intake (replacement condition). The other group underwent the first [18F]FDG PET/CT scan after receiving an rhTSH injection and maintained regular levothyroxine intake (rhTSH condition), and repeated the scan 7 months later during regular levothyroxine intake without rhTSH administration. The intra-group regional brain metabolisms were compared. Results: Under the hypothyroidism condition, brain metabolism was significantly reduced, namely in the bilateral pre-frontal, temporal, anterior cingulate, and primary motor cortices, insula, and striatum (uncorrected voxelwise p Conclusion: rhTSH administration could be a better option than levothyroxine withdrawal for 131I treatment, serum thyroglobulin measurement, or radioiodine scanning for patient follow-up

Brain [18F]Fluorodeoxyglucose Metabolism Assessment under Hypothyroidism and Recombinant Human Thyroid-Stimulating Hormone in Comparison with Thyroid Hormone Replacement in Patients Submitted to Total Thyroidectomy

Objective: To compare brain metabolism using [18F]fluorodeoxyglucose ([18F]FDG) positron emission tomography/computed tomography (PET/CT) in total thyroidectomy patients during hypothyroidism (levothyroxine withdrawal) or under recombinant human thyroid-stimulating hormone (rhTSH) against levothyroxine intake. Methods: A total of 12 patients were randomly divided into two groups. One group underwent the first [18F]FDG PET/CT brain scan after levothyroxine withdrawal (hypothyroidism condition) and repeated the scan 6 months later during regular levothyroxine intake (replacement condition). The other group underwent the first [18F]FDG PET/CT scan after receiving an rhTSH injection and maintained regular levothyroxine intake (rhTSH condition), and repeated the scan 7 months later during regular levothyroxine intake without rhTSH administration. The intra-group regional brain metabolisms were compared. Results: Under the hypothyroidism condition, brain metabolism was significantly reduced, namely in the bilateral pre-frontal, temporal, anterior cingulate, and primary motor cortices, insula, and striatum (uncorrected voxelwise p < 0.005); No significant differences were found between the rhTSH and replacement conditions. Conclusion: rhTSH administration could be a better option than levothyroxine withdrawal for 131I treatment, serum thyroglobulin measurement, or radioiodine scanning for patient follow-up