Relação entre função ventricular esquerda e os índices de captação miocárdio/pulmão em estudos Gated-SPECT

Introdução – A tomografia de emissão de fotão simples sincronizada com o sinal eletrocardiográfico (Gated-SPECT) é essencial para a avaliação conjunta da perfusão e da função ventricular esquerda (VE) do miocárdio. Objetivo – Investigar a relação entre a função VE e o índice de captação (IC) miocárdio/pulmão direito (M/PD) e M/P esquerdo (M/PE) nos estudos Gated-SPECT com 99mTc-Tetrofosmina. Metodologia – Amostra de 32 pacientes que realizaram estudos Gated-SPECT por indicação clínica, sendo subdividida em dois grupos: Grupo I (GI) – pacientes com a informação clínica de enfarte agudo do miocárdio (EAM); Grupo II (GII) – pacientes com a informação clínica de isquemia. Por cada paciente adquiriram-se imagens estáticas torácico-abdominais e dois estudos Gated-SPECT do miocárdio (protocolo de um dia esforço/repouso). Nas imagens estáticas definiram-se regiões de interesse (Regions of interest – ROI) para calcular os IC. Nos estudos Gated-SPECT utilizou-se o software Quantitative Gated SPECT/Quantitative Perfusion SPECT para calcular a Fração de Ejeção do Ventrículo Esquerdo (FEVE). Efetuou-se análise estatística descritiva para caracterização da amostra. Aplicou-se o teste de Spearman para avaliar a correlação entre a FEVE e os IC por grupo de pacientes. O Teste de Willcoxon foi usado para comparar FEVE em repouso e em esforço. Resultados – Nos estudos Gated-SPECT em esforço não se verificou correlação estatisticamente significativa entre a FEVE e os IC, para GI e GII; em repouso existe correlação positiva estatisticamente significativa entre a FEVE e os IC, para GI; para GII não se verificou correlação. Na comparação dos valores de FEVE em esforço e repouso nos dois grupos constatou-se a existência de diferenças estatisticamente significativas, sendo a FEVE em Esforço

A influência do local de estimulação ventricular na incidência de taquiarritmias auriculares em doentes com pacemaker permanente

Mestrado em Tecnologia de Diagnóstico e Intervenção Cardiovascular

Avaliação da função ventricular esquerda por ecocardiografia bidimensional com VVI em indivíduos hipertensos voluntários

Mestrado em Tecnologia de Diagnóstico e Intervenção Cardiovascular - Ramo de especialização: Ultrassonografia Cardiovascular

Value of a lower limb immobilization device for SPECT/CT image fusion optimization

The foot and the ankle are small structures commonly affected by disorders, and their complex anatomy represent significant diagnostic challenges. SPECT/CT Image fusion can provide missing anatomical and bone structure information to functional imaging, which is particularly useful to increase diagnosis certainty of bone pathology. However, due to SPECT acquisition duration, patient’s involuntary movements may lead to misalignment between SPECT and CT images. Patient motion can be reduced using a dedicated patient support. We aimed at designing an ankle and foot immobilizing device and measuring its efficacy at improving image fusion. Methods: We enrolled 20 patients undergoing distal lower-limb SPECT/CT of the ankle and the foot with and without a foot holder. The misalignment between SPECT and CT images was computed by manually measuring 14 fiducial markers chosen among anatomical landmarks also visible on bone scintigraphy. Analysis of variance was performed for statistical analysis. Results: The obtained absolute average difference without and with support was 5.1±5.2 mm (mean±SD) and 3.1±2.7 mm, respectively, which is significant (p<0.001). Conclusion: The introduction of the foot holder significantly decreases misalignment between SPECT and CT images, which may have clinical influence in the precise localization of foot and ankle pathology.

Viability of the use of an A-SiC:H multiplayer device in a domestic VLC application

In this paper the viability of an integrated wavelength optical filter and photodetector for visible light communication (VLC) is discussed. The proposed application uses indoor warm light lamps lighting accomplished by ultra-bright light-emitting diodes (LEDs) pulsed at frequencies higher than the ones perceived by the human eye. The system was analyzed at two different wavelengths in the visible spectrum (430 nm and 626 nm) with variable optical intensities. The signals were transmitted into free space and measured using a multilayered photodetector based on a-SiC:H/a-Si:H. The detector works as an optical filter with controlled wavelength sensitivity through the use of optical bias. The output photocurrent was measured for different optical intensities of the transmitted optical signal and the extent of each signal was tested. The influence of environmental fluorescent lighting was also analysed in order to test the strength of the system. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pt/Carbon materials as Bi-Functional catalysts for N-decane hydroisomerization

The activity and selectivity of bi-functional carbon-supported platinum catalysts for the hydroisomerization of n-alkanes have been studied. The influence of the properties of the carbon support on the performance of the catalysts were investigated by incorporating the metallic function on a series of carbons with varied porosity (microporous: GL-50 from Norit, and mesoporous: CMK-3) and surface chemistry (modified by wet oxidation). The characterization results achieved with H-2 chemisorption and TEM showed differences in surface metal concentrations and metal-support interactions depending on the support composition. The highest metal dispersion was achieved after oxidation of the carbon matrix in concentrated nitric acid, suggesting that the presence of surface functional sites distributed in inner and outer surface favors a homogeneous metal distribution. On the other hand, the higher hydrogenating activity of the catalysts prepared with the mesoporous carbon pointed out that a fast molecular traffic inside the pores plays an important role in the catalysts performance. For n-decane hydroisomerization of long chain n-alkanes, higher activities were obtained for the catalysts with an optimized acidity and metal dispersion along with adequate porosity, pointing out the importance of the support properties in the performance of the catalysts.

Light memory function in a double pin SiC device

A double pi'npin heterostructure based on amorphous SiC has a non linear spectral gain which is a function of the signal wavelength that impinges on its front or back surface. An impulse of a configurable length and amplitude is applied to a 390 nm LED which illuminates one of the sensor surfaces, followed by a time period without any illumination after which an input signal with a different wavelength is impinged upon the front surface. Results show that the intensity and duration of the impulse illumination of the surfaces influences the sensor's response with different output for the same input signal. This paper studies this effect and proposes an application as a short term light memory. (C) 2015 Elsevier B.V. All rights reserved.

Estudo da deformação miocárdica para detecção precoce de disfunção ventricular esquerda em doentes submetidos a quimioterapia com antraciclinas

Mestrado em Tecnologia de Diagnóstico e Intervenção Cardiovascular - Área de especialização: Ultrassonografia cardiovascular

Mobile device-to-device distributed computing using data sets

The rapidly increasing computing power, available storage and communication capabilities of mobile devices makes it possible to start processing and storing data locally, rather than offloading it to remote servers; allowing scenarios of mobile clouds without infrastructure dependency. We can now aim at connecting neighboring mobile devices, creating a local mobile cloud that provides storage and computing services on local generated data. In this paper, we describe an early overview of a distributed mobile system that allows accessing and processing of data distributed across mobile devices without an external communication infrastructure. Copyright © 2015 ICST.

Light memory operation based on a double pin SiC device

Experimental optoelectronic characterization of a p-i'(a-SiC:H)-n/pi(a-Si:H)-n heterostructure with low conductivity doped layers shows the feasibility of tailoring channel bandwidth and wavelength by optical bias through back and front side illumination. Front background enhances light-to-dark sensitivity of the long and medium wavelength range, and strongly quenches the others. Back violet background enhances the magnitude in short wavelength range and reduces the others. Experiments have three distinct programmed time slots: control, hibernation and data. Throughout the control time slot steady light wavelengths illuminate either or both sides of the device, followed by the hibernation without any background illumination. The third time slot allows a programmable sequence of different wavelengths with an impulse frequency of 6000Hz to shine upon the sensor. Results show that the control time slot illumination has an influence on the data time slot which is used as a volatile memory with the set, reset logical functions. © IFIP International Federation for Information Processing 2015.