胸部CT图像中孤立性肺结节良恶性快速分类

目的：为突破医学影像诊断学依据医学征象进行定性诊断准确度不高的瓶颈,针对胸部CT图像中孤立性肺结节（SPN）定性诊断问题,寻求能够有效表示SPN病理特性的图像特征,实现快速准确地SPN良恶性计算机辅助诊断系统。方法：首先,采取交互式分割方法从胸部CT图像中提取出SPN;其次,直接计算SPN图像的多分辨率直方图得到768维空间信息特征样本集;然后,充分利用具有处理高维数据集优势的支持向量机（SVM）构造SPN良恶性分类器;最后,通过测试样本集对经训练后的SVM分类器进行测试以评价分类性能。结果：经214例病例实验结果表明：240个SPN图像的768维特征计算所用时间为4.83秒,SVM分类器训练测试所用时间为2.24秒,敏感性71.33%,特异性70%,准确度71.67%,接受者操作特性曲线(ROC)下面积(AUC) 0.7864。结论：该系统提取的高维图像空间信息特征能够有效表示SPN特性;没有考虑医学征象进行SPN定性诊断的准确度就达到了71.67%,同时分类速度比传统纹理算法提高了近50倍,为医学影像学解决SPN定性诊断问题提供了便捷、客观的辅助手段。     

Comparison of diagnostic accuracy between ^18F-FDG PET and PET/CT for pulmonary neoplasm

Aimed at comparing diagnostic accuracy of 18F-FDG PET with PET/CT for pulmonary neoplasm,a study based on multi-center clinical trial of the diagnoses,in randomized and semi-blind ways,was executed from January 2006 to June 2007.It included 55 patients,i.e.16 with histopathologically proved lung tumors,16 with tuberculosis and 23 with benign lesions (inflammation,pseudotumor,granuloma,fibrosis and others).The histopathologic and clinic results were served as reference standard.Statistical significances in pulmonary nodule diagnosis between 18F-FDG PET and PET/CT were determined with 95% confidence interval obtained by ROC analysis.The 18F-FDG PET detected lung neoplasm with a sensitivity of 87.5% (14/16),a specificity of 59.0% (23/39),an accuracy of 67.3% (37/55) and a positive-likelihood ratio of 2.13.The 18F-FDG PET/CT detected lung neoplasm with a sensitivity of 93.8% (15/16),a specificity of 61.5% (24/39),an accuracy of 70.9% (39/55) and a positive-likelihood ratio of 2.43.The area under curves (AUC) of 18F-FDG PET and PET/CT were 0.803±0.068 and 0.799±0.063,respectively.It can be concluded that the diagnostic accuracy for malignant pulmonary nodules between 18F-FDG PET and PET/CT was not statistically different.     

人工气道内持续湿化护理观察

目的探讨气道内持续湿化方法对人工气道建立患者预防肺部感染的护理治疗效果。方法 35例进入急诊科和重症监护室的人工气道建立患者随机分成实验组20例和对照组15例,实验组患者采用微量注射泵持续湿化的方法对人工气道进行护理,对照组采用常规护理方法间断给予气道内湿化的方法对人工气道进行护理,分别观察记录2组患者体温、吸痰间隔时间、拔管时间并进行痰液细菌培养,主要以体温和痰液细菌培养结果判断是否有肺部感染的发生评价疗效,卡方检验方法对临床采集数据进行统计学处理。结果实验组与对照组比较,实验组发生肺部感染例数明显减少,统计学处理差异有显著性。结论与传统的间断气道湿化相比,采用微量注射泵持续气道湿化操作简单,安全可靠,效果确切,并发症少。     

A novel application of microsphere perfusion and scanning electron microscopy to the identification of pulmonary arterioles in guinea-pig and rabbit lungs

In arterioles of the lung the intravascular blood pressures are lower than in comparable vessels in the systemic circulation and the arteriole walls are thinner. Therefore, it is very difficult to distinguish between arterioles and venules of the same size using scanning electron microscopy. This study describes a novel application of latex microsphere perfusion and scanning electron microscopy which distinguishes between pulmonary arterioles and venules on the basis of endothelial cell morphology. Microspheres, 90 and 45 μm in diameter, were perfused into the arterial side of the pulmonary circulation of guinea-pig and rabbit lungs. Scanning electron microscopy of the arterioles on both sides of the lodged microspheres indicated that the endothelial cells are spindle shaped. In contrast, the endothelial cells of equal diameter venules are polygonal. Furthermore, the nuclei of the arteriolar endothelial cells were significantly (P = 0·019) narrower than those of endothelial cells in venules of equal diameter. Finally, it was observed that the differences between arteriole and venule endothelial cells persisted distally to the capillaries.     

Characteristics of solitary waves on a running film down an inclined plane under an electrostatic field

For the study on the nonlinear dynamics of thin-film flow running down an inclined plane under the effect of an electrostatic field, the mechanism of solitary waves has been examined by using a global bifurcation theory. First, the existence of solitary waves has been chased by using an orbit homoclinic to a fixed point of saddle-focus type in a linearized third-order ordinary differential equation which resulted from the evolution equation in a steady moving frame. Then, the trajectories with several kinds of solitary waves have also been searched numerically for the nonlinear system. In addition, the behavior of these waves has been directly confirmed by integrating the initial-value problem. The slightly perturbed waves at the inception eventually evolve downstream into almost permanent pulse-like solitary waves through the processes of coalescence and repulsion of the triggered subharmonics. In the global aspects the flow system at a given Reynolds number becomes more unstable and chaotic than when there is no electrostatic force applied.     

Review of pulmonary toxicity of indium compounds to animals and humans

Due to the increased production of ITO, the potential health hazards arising from occupational exposure to this material have attracted much attention. This review consists of three parts: 1) toxic effects of indium compounds on animals, 2) toxic effects of indium compounds on humans, and 3) recommendations for preventing exposure to indium compounds in the workplace.Available data have indicated that insoluble form of indium compounds, such as ITO, indium arsenide (InAs) and indium phosphide (InP), can be toxic to animals. Furthermore, InP has demonstrated clear evidence of carcinogenic potential in long-term inhalation studies using experimental animals. As for the dangers to humans, some data are available concerning adverse health effects to workers who have been exposed to indium-containing particles. The Japan Society for Occupational Health recommended the value of 3 μg/L of indium in serum as the occupational exposure limit based on biological monitoring to preventing adverse health effects in workers resulting from occupational exposure to indium compounds. Accordingly, it is essential that much greater attention is focused on human exposure to indium compounds, and precautions against possible exposure to indium compounds are most important with regard to health management among indium-handling workers.     

High-temperature oxidation of duplex stainless steels in air and mixed gas of air and CH4

TGA, isothermal and thermal-cycle tests were carried out to investigate the oxidation behaviour of duplex stainless steels at 1220 °C in various atmospheres. The weight gain in air is initially in parabolic relation to time. This is followed by a linear relationship for super alloy and a dramatic growth one for standard alloy that is subject to breakaway oxidation by forming nodules. The thickness of γ-layer increases with increasing annealing time and oxygen content in the atmosphere, and it is slightly higher in standard alloy than in super alloys. A single layer of (Fe,Cr)₃O₄ spinel is noticed in the external oxide scale after annealing for 2 h, and two layers are found after 4 h with an inner layer of the spinel and an outer layer of iron oxides. Nodules grow on the δ/γ packets where the oxidation of austenite is accelerated and that of ferrite is suppressed. Both chains and Si-enriched scales grow inside the γ-layer along grain and phase boundaries.     

A tester for artificial respirators

All equipment used for resuscitation must be validated before use. This is possible only if means are available for simulating the human airways and lungs, reproducing the conditions in which the respirators will be employed. It is also important that such simulators be capable of determining all variables (flow rate, respiratory rate, pressure, etc.) that can be regulated with an artificial ventilator in full agreement with international standards. This paper illustrates the development of a lightweight, portable prototype lung model with a compliant bellows whereby various lung conditions can be simulated. The prototype was validated using a fixed-capacity reference model which ensures good measurement accuracy, though its weight and bulk are by no means inconsiderable. The investigation was carried out by sizing each component in accordance with international and American standards.     

A model of ventilation of the healthy human lung

This paper presents a model of the lung mechanics which simulates the pulmonary alveolar ventilation. The model includes aspects of: the alveolar geometry; pressure due to the chest wall; pressure due to surface tension determined by surfactant activity; pressure due to lung tissue elasticity; and pressure due to the hydrostatic effects of the lung tissue and blood. The cross-sectional area of the lungs in the supine position derived from computed tomography is used to construct a horizontally layered model, which simulates heterogeneous ventilation distribution from the non-dependent to the dependent layers of the lungs. The model is in agreement with experimentally measured hysteresis of the pressure-volume curve of the lungs, static lung compliance, changes in lung depth during breathing and density distributions at total lung capacity (TLC) and residual volume (RV). In the dependent layers of the lungs, alveolar collapse may occur at RV, depending on the assumptions concerning lung tissue elasticity at very low alveolar volumes. The model simulations showed that ventilation increased with depth in the lungs, although not as pronounced as observed experimentally. The model simulates alveolar ventilation including all of the mentioned components of the respiratory system and to be validated against all the above mentioned experimental data.     

Patient specific identification of the cardiac driver function in a cardiovascular system model

The cardiac muscle activation or driver function, is a major determinant of cardiovascular dynamics, and is often approximated by the ratio of the left ventricle pressure to the left ventricle volume. In an intensive care unit, the left ventricle pressure is usually never measured, and the left ventricle volume is only measured occasionally by echocardiography, so is not available real-time. This paper develops a method for identifying the driver function based on correlates with geometrical features in the aortic pressure waveform. The method is included in an overall cardiovascular modelling approach, and is clinically validated on a porcine model of pulmonary embolism. For validation a comparison is done between the optimized parameters for a baseline model, which uses the direct measurements of the left ventricle pressure and volume, and the optimized parameters from the approximated driver function. The parameters do not significantly change between the two approaches thus showing that the patient specific approach to identifying the driver function is valid, and has potential clinically.