Assuntos
Agressão , Alouatta/psicologia , Comportamento Predatório , Isolamento Social , Animais , Feminino , Geografia , Masculino , México , Comportamento SocialAssuntos
Coração/diagnóstico por imagem , Cateterismo Cardíaco , Doença da Artéria Coronariana/diagnóstico por imagem , Difosfatos , Doenças das Valvas Cardíacas/diagnóstico por imagem , Ventrículos do Coração/diagnóstico por imagem , Humanos , Radioisótopos , Cintilografia , Tecnécio , Pirofosfato de Tecnécio Tc 99m , TálioRESUMO
This article describes a method for inhalatory lung scintigraphy (ILS) by the use of radioactive monodisperse aerosols, with particles smaller than 2 microns. We discuss the findings in normal subjects, in patients with pulmonary embolism (PE) or/and obstructive pulmonary disease (OPD), and in individuals with severe pulmonary hypertension. This procedure has several advantages over the use of radioactive gases, such as 133Xe and 81Krm: lower cost, easier to perform, several scintigraphic projections in one study, acquisition of perfusion and inhalatory images in a single session, and inhalatory and perfusion images with identical spatial resolution and similar data density. It is concluded that ILS with radioactive monodisperse aerosols is a useful method for the study of OPD and in conjunction with perfusion lung scintigraphy is helpful in the diagnosis of PE.
Assuntos
Hipertensão Pulmonar/diagnóstico por imagem , Pneumopatias Obstrutivas/diagnóstico por imagem , Pulmão/diagnóstico por imagem , Ácido Pentético , Embolia Pulmonar/diagnóstico por imagem , Tecnécio , Aerossóis , Diagnóstico Diferencial , Humanos , Ácido Pentético/administração & dosagem , Cintilografia , Tecnécio/administração & dosagem , Pentetato de Tecnécio Tc 99mRESUMO
The natural history of pulmonary embolism is described, together with the physiopathologic alterations and the clinical manifestations of this disease, correlating these with the various patterns of pulmonary perfusion usually found by lung scintigraphy with 99mTc-MAA in patients with thromboembolic lung disease. By using data found in the literature, the operating characteristics (sensitivity, specificity, and accuracy) and the predictive values of the different scintigraphic patterns, were calculated for populations with different prevalences of pulmonary embolism. It is concluded that perfusion lung scintigraphy is a non-invasive, objective and fast procedure, very sensitive to alterations of the regional blood flow, but that is not specific for embolism. In some cases it can replace pulmonary angiography but in others, its results may indicate the performance of invasive procedures.
Assuntos
Embolia Pulmonar/diagnóstico por imagem , Humanos , Pulmão/diagnóstico por imagem , Pulmão/fisiopatologia , Artéria Pulmonar/diagnóstico por imagem , Circulação Pulmonar , Embolia Pulmonar/fisiopatologia , Cintilografia , Agregado de Albumina Marcado com Tecnécio Tc 99mRESUMO
A new method is introduced for the superposition of 99mTc-pyrophosphate (PiF) myocardial images on the isolated images of the radioangiocardiographic dextrophase and levophase, in order to include cardiac anatomical references for the accurate topographic localization of the PiF concentration areas. Results in two different patients are presented. In one of them, the PiF concentration was evident at the inferoseptal, inferoapical and posterolateral regions of the left ventricle. In the other, the PiF concentration was evident at the same areas than in the former plus the inferoanterior region of the right ventricle. Our project is to validate this procedure by correlating its results with those obtained through other clinical methods that detect right ventricular infarction.
Assuntos
Difosfatos , Infarto do Miocárdio/diagnóstico por imagem , Tecnécio , Angiocardiografia/métodos , Humanos , Infarto do Miocárdio/patologia , Intensificação de Imagem Radiográfica , Cintilografia , Pirofosfato de Tecnécio Tc 99mRESUMO
We show the first clinical images obtained by a new tomographic system based on the detection of the scattered gamma photons of 99mTc by the chest tissues. These images show satisfactory contrast and tomographic effect on the half-chest near the radioactive source. Both effects tend to decrease on the contralateral half-chest. The images rendered important data in differential diagnosis of perfusion defects evident by lung scintigraphy with macroaggregated albumin labeled with 99mTc. Pulmonary density was normal and homogeneous in a healthy volunteer and also in a patient with pulmonary embolism. It demonstrated a hyperdense pulmonary mass in a patient with tumor of the right lung, which produced a perfusion defect evident in the conventional lung scintiscan, and a shadow in the gamma ray transmission image.
Assuntos
Tórax/diagnóstico por imagem , Tomografia Computadorizada de Emissão/métodos , Feminino , Humanos , Pulmão/diagnóstico por imagem , Neoplasias Pulmonares/diagnóstico por imagem , Embolia Pulmonar/diagnóstico por imagem , Tecnécio , Agregado de Albumina Marcado com Tecnécio Tc 99m , Tomografia Computadorizada de Emissão/instrumentaçãoRESUMO
This article describes the transformation of the gamma-camera images into digital form. The incidence of a gamma photon on the detector, produces two voltage pulses, which are proportional to the coordinates of the incidence points, and a digital pulse, indicative of the occurrence of the event. The coordinate pulses passes through a analog-digital converter, that is activated by the pulse. The result is the appearance of a digital number at the out-put of the converter, which is proportional to the voltage at its in-put. This number, is stored on the accumulation memory of the system, either on a list mode or on a matrix mode. Static images can be stored on a single matrix. Dynamic data can be stored on a series of matrixes, each representing a different period of acquisition. It is also possible to capture information on a series of matrixes syncronized with the electrocardiogram of the patient. In this instance, each matrix represents a distinct period of the cardiac cycle. Data stored on the memory, can be used to process and display images and quantitative histograms on a video screen. In order to do that, it is necessary to translate the digital data on the memory to voltage levels, and to transform these on light levels on the screen. This, is achieved through a digital analog converter. The reading of the digital memory must be syncronic with the electronic scanning of the video screen.
Assuntos
Cardiopatias/diagnóstico por imagem , Coração/diagnóstico por imagem , Cintilografia/instrumentação , Conversão Análogo-Digital , Computadores , Apresentação de Dados , HumanosRESUMO
Attenuation of gama radiation (140 KeV) from a punctual source of 99mTc was investigated in materials with a similar density to that of human chest tissues: air, saw dust (lungs), and water (chest wall and mediastinic organs). Half-value thickness (A 1/2) and linear attenuation coefficients (u) were measured for each material. With these experimental data, attenuation of the primary radiation beam and intensity of Compton effect at an angle of 90 degrees were calculated at different depths of a theoretical model of a human chest, assuming a primary radiation beam with a direction from right-to-left, and the inverse. The results demonstrated the theoretical possibility of obtaining quantitative tomographic bidimensional images of the tissular densitometry of the hemi-tórax near the radiation source, by means of the detection of the gama photons scattered al 90 degrees as a result of Compton effect. Attenuation of the primary beam prevents the obtaintion of information from the far sided hemitorax. Theoretical considerations for the correction of this defect of the low energy gama photons from 99mTc are discussed. It was decided to design and built a system for the experimental evaluation of this new principle for clinical exploration, which can be used as a low cost and simple adjuvant to increase the specificity of perfusion lung scintigraphy.
Assuntos
Pulmão/diagnóstico por imagem , Embolia Pulmonar/diagnóstico por imagem , Cintilografia/métodos , Tecnécio , Densitometria , Raios gama , Humanos , Modelos Biológicos , Perfusão , Cintilografia/instrumentação , Espalhamento de Radiação , Pertecnetato Tc 99m de SódioRESUMO
Based on a previous theoretical study, a simple device for the acquisition of bidimensional tomographic images of the human chest densitometry was designed. A radioactive linear source (99mTc) was adapted to the lateral aspect of a gamma camera detector in order to register only those photons scattered at 90 degrees. Resulting images from a liver phantom stuffed with saw dust, showed an evident tomographic effect and a satisfactory contrast between the structures sited at less than 20 cm from the source. These effects tend to decrease with distance. The causes of these deficiencies of the system and their possible corrections are discussed.
Assuntos
Modelos Estruturais , Tecnécio , Tórax/diagnóstico por imagem , Tomografia Computadorizada de Emissão , Estudos de Avaliação como Assunto , HumanosRESUMO
This article describes the internal structure and organization of digital systems in use for processing the data information obtained through the in vivo applications of radioactive tracers in cardiology.