Assessment of different regions of interest-based methods for [99mTc]Tc DAT-SPECT quantification using an anthropomorphic striatal phantom.

BACKGROUND AND AIMS: Molecular imaging of the dopamine transporters (DAT) provides valuable information about neurodegenerative diseases, such as Parkinson's. This study assessed the accuracy and precision of DAT-SPECT quantification methods. METHODS: Twenty-three DAT-SPECT images of a striatal phantom were acquired. The specific (caudate and putamen) and the non-specific (background activity) chambers were filled with [99mTc]Tc. Different specific-to-non-specific activity ratios (10, 9, 8, 7, 6, 5, 4, 3 and 2 to 1) and the specific binding ratio (SBR) were calculated. Five methods using ROIs were assessed: (a) Manual ROIs on SPECT images; (b) TwoBox and (c) ThreeBox methods and Volume of Interest (VOI) using structural images; (d) MRI and (e) CT. Accuracy was evaluated by the concordance correlation coefficient (CCC) and precision by Pearson's coefficient and linear regression. RESULTS: The SBR quantified in the specific and striatal chambers resulted in a CCC increase with a decrease in the nominal values. For lower SBR, MRI and CT showed higher CCCs when caudate ([Formula: see text] = 0.89 e [Formula: see text] = 0.84) and putamen ([Formula: see text] = 0.86 e [Formula: see text] = 0.82) were evaluated. For striatal assessments, the TwoBox method was the most accurate ([Formula: see text] = 0.95). High Pearson's coefficients were found in the correlations between all methods. CONCLUSIONS: All five methods showed high precision even when applied to images with different activities. MRI and CT were the most accurate for assessing the caudate or putamen. To assess the striatal chamber and in the absence of structural information, the TwoBox method is advisable.

Linear and nonlinear measures of fetal heart rate patterns evaluated on very short fetal magnetocardiograms.

We analyzed the effectiveness of linear short- and long-term variability time domain parameters, an index of sympatho-vagal balance (SDNN/RMSSD) and entropy in differentiating fetal heart rate patterns (fHRPs) on the fetal heart rate (fHR) series of 5, 3 and 2 min duration reconstructed from 46 fetal magnetocardiograms. Gestational age (GA) varied from 21 to 38 weeks. FHRPs were classified based on the fHR standard deviation. In sleep states, we observed that vagal influence increased with GA, and entropy significantly increased (decreased) with GA (SDNN/RMSSD), demonstrating that a prevalence of vagal activity with autonomous nervous system maturation may be associated with increased sleep state complexity. In active wakefulness, we observed a significant negative (positive) correlation of short-term (long-term) variability parameters with SDNN/RMSSD. ANOVA statistics demonstrated that long-term irregularity and standard deviation of normal-to-normal beat intervals (SDNN) best differentiated among fHRPs. Our results confirm that short- and long-term variability parameters are useful to differentiate between quiet and active states, and that entropy improves the characterization of sleep states. All measures differentiated fHRPs more effectively on very short HR series, as a result of the fMCG high temporal resolution and of the intrinsic timescales of the events that originate the different fHRPs.

Influência do repouso e alongamento na atividade elétrica muscular após digitação / Influence of rest and stretching on muscle eletric activity after typing

Com o crescente aumento da velocidade e ritmo das atividades laborais, o trabalhador atual sofre maior sobrecarga nas estruturas musculotendíneas.Visando a recuperação dessas estruturas e a prevenção de lesões ocupacionais...

Labour activities increasing speed and rhythm have led to overcharge on workers' muscle-tendon structures. Aiming at recovering such structures and preventing occupational lesions, some companies...

Análise da força muscular em indivíduos treinados na plataforma de instabilidade / Analysis of the muscular force in subjects trained in the platform of instability

O objetivo do estudo foi comparar a variabilidade do grau de força muscular pelo teste 10 repetições máximas (RM) antes e depois do treinamento de força na execução do exercício agachamento no Smith Machine em indivíduos treinando com e sem a plataforma de instabilidade (PI). A amostra foi composta de 30 homens jovens, com idades entre 20 e 25 anos, peso entre 75 e 80 Kg e altura entre 175 e 180 cm. Os indivíduos foram separados aleatoriamente em 3 grupos: 1) grupo plataforma de instabilidade (GPI); 2) grupo padrão (GP); 3) grupo controle (GC). Todos os indivíduos realizaram o teste de 10RM 48 H antes do 1º dia de treinamento e 48 H depois do último dia de treinamento. Os indivíduos do GPI e do GP realizaram o treinamento de força 3 vezes por semana durante 4 semanas com a carga constante (carga do teste 10RM) e ao final de cada treinamento respondiam a escala de percepção subjetiva de esforço (PSE). A ANOVA de duas entradas, seguida, pelo teste post hoc de Tuckey mostrou diferença significativa entre o teste e o reteste 10RM no GP e no GPI (p<0,0001, ambos os grupos), sem mudanças no GC (P>0,05). As médias do reteste comparadas entre os grupos mostraram redução significativa no GP (P<0,02) e GC (P<0,0001) em relação ao GPI. As médias do GP apresentaram aumento significativo em relação ao GC (P<0,01). Em relação a PSE o teste t-student mostrou valores próximos ao absoluto em ambos os grupos (GPI e GP) após a 4º semana de treinamento, e as médias intergrupos relataram diferença significativa (10,6+ 0,6 – GP; 11,8+ 0,2 – GPI, P<0,0001). A conclusão mostrou que o treinamento com instabilidade gera através da adaptação neural habilidade de maior coordenação inter e intramuscular, conseqüentemente, melhora da atividade dos agonistas, sinergistas, estabilizadores, assim, apresentou aumento da produção de força, quando comparado com ações de estabilidade.

The aim of the study was to compare the variability of the degree of muscular force for the test 10 maximum repetitions (RM) before and after the strength training in the execution of the exercise squat in individuals with and without the platform of instability (PI). The sample was composed of 30 young men, with ages between 20 and 25 years, body weight between 75 and 80 kg and height between 175 and 180 cm. The individuals were separate in 3 groups: 1) group platform of instability (GPI); 2) group pattern (GP); 3) group control (GC). All of the individuals accomplished the test of 10RM 48 H before the 1st day of training and 48 H after the last day of training. The individuals of GPI and of GP they accomplished the strength training per 3 times for 4 weeks with the constant load (load of the test 10RM) and at the end of each training they answered the scale of subjective perception of effort (SPE). The ANOVA two way from post hoc Tuckey results showed significant difference between the test and the retest 10RM in GP and in GPI (p <0.0001, both groups), without changes in GC (P>0.05). The averages of the retest compared among the groups showed significant reduction in GP (P <0.02) and GC (P <0.0001) in relation to GPI. The averages of GP presented significant increase in relation to GC (P <0.01). SPE told himself close values to the absolute in both groups (GPI and GP) after to 4th week of training, and the averages inter-groups told significant difference (10,6+ 0,6 - GP; 11,8+ 0,2 - GPI, P <0.0001). The conclusion shows that the training with instability generates through the adaptation neural, ability of larger coordination inter and intramuscularly, consequently, it gets better of the activity of the agonists, synergists, stabilize. However showed increase of the production of force, when compared with actions of stability.