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Kearns-Sayre syndrome is a rare mitochondrial disease which usually occurs sporadically with the presence of ptosis and the clinical triad of chronic progressive external ophthalmoplegia, atypical retinitis pigmentosa and cardiac conduction disorders. We show on the example of a young patient with unexplained atypical acquired ptosis and eye movement disorders, the correct interpretation of the diagnostic findings. Of importance is the early detection of potentially life-threatening complications which can lead to sudden cardiac death.

Numerous respiratory disorders may be responsible for right heart dysfunction, frequently suboptimally assessed in routine clinical practice. Multidetector-row CT systems with fast scanning capabilities can acquire images of the thorax with reduced cardiac motion artifacts, enabling improved evaluation of the heart. Moreover, the introduction of fast rotation speed and dedicated cardiac reconstruction algorithms exploiting the multislice acquisition scheme of the data has opened the possibility of integrating right cardiac functional information into a diagnostic CT scan of the chest, without or with ECG gating.

The influence of properties of metals (copper, tantalum, titanium, TiAl and nickel) constituting the cathode on the characteristics of a hollow cathode discharge has been investigated for different pressures and currents. We point out that the phase transformations of the cathode material induce a modification in the current-voltage characteristics of the discharge. This phase transformation effect of the cathode material combines with the geometrical effect induced by the typical hollow cathode discharge which seems to be independent of the material properties. The evolution of the electron density and the evolution of the intensities of emission lines in the plasma are also affected by the phase transition. This effect is related to a work function change of the metal at the phase transition. It can be used as a test of work function variation of materials or for optimization of plasma processes.

Recent years have seen growing interest in the development of algorithms for computer-assisted diagnosis (CAD) for the detection of pulmonary nodules on both plain-film radiographs and computed tomography (CT) studies. The purpose of CAD algorithms in this context is to alert radiologists to suspicious radioopacities that might represent cancer in the images. We are developing a CAD system for the detection of pulmonary nodules on helical CT images.We collected cases of patients with pulmonary nodules examined with helical CT. A total of 64 nodules, including both calcified and noncalcified lesions, ranging from 3 to 30 mm in diameter were included in the study. Studies were acquired on one 4-slice and one 64-slice CT scanners. Three chest radiologists at two institutions interpreted the studies to determine whether pulmonary nodules were present. We calculated the sensitivity and the number of false positives per image to evaluate the CAD system.We have developed and evaluated an algorithm for the automatic detection of pulmonary nodules on CT images. For a sensitivity of 76%, the false-positive rate was 1.3 per image.Our preliminary results suggest that the system might be useful for radiologists in the detection of pulmonary nodules on helical CT images.

4 pages; International audience; This paper reminds the drawbacks of classical voice-coil motors and presents a way to improve them. Two ironless and leakage free structures are presented, one using traditional sintered magnets and other one using bonded magnets, giving the pros and cons of each solution. A 2-D analytical model using the Coulombian approach is used to calculate and compare the performances of both structures. Then, in order to evaluate the relevance of the 2-D model for magnet rings, a comparison is doe with a 3-D analytical model for several radii of rings.

This paper focuses on the design of a nonlinear model predictive control (NMPC) scheme for a cement grinding circuit, i.e., a ball mill in closed loop with an air classifier. The multivariable controller uses two mass fractions as controlled variables, and the input flow rate and the classifier selectivity as manipulated variables. As the particle size distribution inside the mill is not directly measurable, a receding-horizon observer is designed, using measurements at the mill exit only. The performance of the control scheme in the face of measurement errors and plant-model mismatches is investigated in simulation.

State estimation methods allow the vehicle position and velocity to be reconstructed by combining information from sensors and vehicle model. From a security point of view, position and velocity have to be known with a high level of confidence in order, for example, to avoid vehicle collision. In this paper, a confidence interval observer is developed to enclose positioning variables with some confidence degree (or integrity level). For this purpose, the algorithm is divided in two parts. First, a predictor, based on the vehicle dynamics, is derived to estimate bounds on state variables with lower bounded integrity. Then, at each measurement time, confidence intervals from the sensors are combined with union and intersection operations to satisfy the integrity level. The shortest non-empty intervals are chosen among the safe intervals. Finally, to quantify the reliability of estimation, a security measure is defined by the probability of having one faulty estimation in some period of time and is related to the integrity level objective. This method is illustrated with simulation tests based on an autonomous underwater vehicle described by a nonlinear model.

The association between idiopathic pulmonary fibrosis and patent foramen ovale has rarely been described.We report the cases of two patients, 72 and 59 years old, who presented with refractory hypoxemia in the context of pulmonary fibrosis. The hypoxemia was due to a right-to-left shunt through a patent foramen ovale (PFO), diagnosed by transoesophageal contrast echocardiography. The closure of the PFO allowed a decrease in the oxygen requirement in the first case: from 8 l/min to 3 l/min (PaO2 80 mmHg), and in the second case oxygen therapy could be stopped (PaO2 76 mmHg on room air). Right-to left shunts by PFO are usually associated with pulmonary arterial hypertension (systolic pulmonary arterial pressure at 70 mmHg for case 1), but in some cases the pulmonary artery pressure is normal (case 2), the shunt being due to an anatomical conformation.These two cases underline the importance of diagnosing right-to-left shunts in patients who have pulmonary fibrosis with severe hypoxemia, in order to reduce their oxygen needs.

The cause of protein-losing enteropathy is sometimes difficult to establish. It can be rarely due to a constrictive pericarditis.We report a patient presenting a protein-losing enteropathy revealing a constrictive pericarditis.Chronic pericarditis should be evoked in case of unexplained protein-losing enteropathy. Echocardiography can sometimes be normal. Therefore, chest computed tomography scan or cardiac MRI followed by confirmation right heart catheterization should be performed in case of persistent unexplained protein-losing enteropathy.

K. L. RIBEIRO', 0. D. AGUIAR, S. FURTADO, C. FRAJUCA, P. J. CASTRO, J. J. BARROSO AND M. REMY 1 Instituto National de Pesquisas Espaciais Divisdo de Astrofisica Av. dos Astronautas 1758, Sao Jose dos Campos, 12227-010 SP, Brazil Fundagao Educational de Caratinga Departamento de Fisica Avenida Moacyr de Mattor, 49 Caratinga, 35000-000, MG, Brazil Centro Federal de Ensino Tecnologico de Sao Paulo, Sao Paulo, SP, Brazil E-mail: kilder@das.inpe.br

A number of recent investigations (e.g. Webster et al., 1988; Fugmann, 1988) have presented evidence in favour of an excess of galaxies in the fields of distant QSOs. This excess is generally interpreted as a manifestation of the gravitational magnification of the background QSO by matter associated with the foreground galaxies. Having collected a significant number of images of highly luminous QSOs, we decided to analyse them in order to search for the presence of such an effect in our sample (for a description of our survey, see Surdej et al., 1988a, b and Swings et al., 1989). To improve the contrast in favour of galaxy detections, we kept only the images taken through a red filter (Bessel R ESO serial number 421 or 447). 83 images were selected: 40 obtained with EFOSC at the ESO 3.6 m telescope and 43 with a direct CCD camera at the ESO/MPI 2.2 m telescope. The limiting R magnitude of these images generally ranges, for stellar objects, between 22.5 and 23.0.

International audience; Previous studies have pointed out the advantages of using a pulsed discharge for diamond growth by microwave plasma assisted chemical vapour deposition (MPACVD): increase of the growth rate and/or enhancement of the diamond quality. It has been shown that the duration of the pulse and that of the pause between two pulses have a particular influence on the deposition process. Optimal values can be determined that depends mainly on the geometry and size of the reactor and on the working conditions. In the present work, new results are obtained in a MPACVD reactor working in a pulsed plasma mode, H2/CH4 gas mixture and 6 kW peak power. These conditions are similar to those of industrial reactors. The most important species in such process are CHx, C2Hy and H, which are considered, respectively, as the key species for diamond deposition, graphite deposition and graphite etching. A particular interest was devoted to the atomic hydrogen evolution during the discharge phase and the afterglow. Quantitative measurements of H-atom ground state concentration are carried out by two-photon Laser Induced Fluorescence (LIF). The study of the kinetic processes which are responsible of atomic hydrogen creation and loss permits us to determine the production rate of H-atoms in pulsed mode as compared with the continuous one (CW), and leads to a better understanding of its influence on the diamond growth rate and its chemical quality as estimated by micro-Raman spectroscopy. The correlation established between the results of the diamond film analysis and the plasma characteristics points out the benefit of this study for the optimisation and the control of the diamond growth process by pulsed MPACVD.

The diagnostic performance of computed tomography images of pulmonary embolism is directly related to the acquisition parameters. Any physician evaluating these scans must have proper knowledge of the acquisition, injection, reconstruction, and radiation parameters. Cardiac gating and morphological and functional image processing should be understood since they are now routine techniques particularly important for preoperative assessment of chronic thromboembolism. Elementary knowledge of the imaging techniques reduces the risk of diagnostic limitations. Understanding these techniques does not require any particularly advanced knowledge of physics, data processing or technology, but is necessary to chose the appropriate technical facilities and equipment adapted for diagnostic purposes. While specific training is not a prerequisite, interpretation of an angioscan of the pulmonary vessels does require precise knowledge of the pulmonary anatomy in addition to the technical knowledge mentioned above. Proper analysis may reach the 4th and 5th generation vessels. Different analysis methods have been developed which take into account the technical parameters and avoid the need for serial images. Each slice can then be analyzed within an acquisition Volume. Differential diagnosis is also very technique-dependent, minimally operator-dependent but highly machine-dependent. Differential diagnosis becomes less and less a problem with advancing equipment. Sufficient knowledge of the physiological and pathogenic basis is relatively easy to retain.

Pulmonary embolism (PE) is a common condition with considerable morbidity and mortality [1]. Prompt and accurate diagnosis is important because the mortality of untreated pulmonary embolism is high and serious complications can occur with its treatment, long-term anticoagulation [2]. Because there are no specific signs or symptoms of this condition, the diagnosis relies on imaging tests. In the early 1990s, the introduction of spiral computed tomography (CT) technology dramatically modified the evaluation of pulmonary arteries, enabling a direct insight into endovascular abnormalities and thus a direct depiction of endoluminal clots. Successive technological advances have reinforced its diagnostic impact, explaining why this imaging tool is now included in the noninvasive diagnostic algorithms proposed in routine clinical practice. The purpose of this article is to focus on multislice spiral CT angiography in the management of thromboembolic disease.

Microwave plasma assisted chemical vapour deposition in hydrogen–methane gas mixture is one of the most widespread methods used for the growth of diamond thin films. It has been proved that at low microwave power (300 W) the modulation of the power can lead to a significant improvement of the growth rate or the quality of diamond films. In this work, we show that this advantage can be validated at an industrial scale in reactors working at higher power (peak power up to 6 kW). The pulsed mode operation shows that whatever the frequency or the duty cycle, the quality of diamond (according to the micro-Raman spectroscopy) can be appreciably improved at the same growth rate. An optimal range of temporal parameters as the pulse and afterglow duration, corresponding to an optimal range of frequency and duty cycle has been determined. The main reactive species observed by optical emission spectroscopy in such plasmas are the CH and C 2 radicals as well as atomic hydrogen. The chemistry of CH 4 /H 2 discharge is very rich in hydrocarbon radicals. Nevertheless, some works have shown that the CH x radicals are the key species for the diamond deposit whereas C 2 H y is rather responsible for the graphite growth and the atomic hydrogen preferentially for the graphite etching. Time resolved optical emission spectroscopy and double pulse technique have been carried out to investigate the evolution of the active species during the discharge on-time as well as during the afterglow. These plasma studies lead to a better understanding of the advantages in modulating the power and allow establishing some correlations between the temporal evolution of the observed species and the characteristics of the deposited films.

Dynamic mathematical models in biotechnology require, besides the information about the stoichiometry of the biological reaction system, knowledge about the reaction kinetics. Modulation phenomena like limitation, inhibition and activation occur in different forms of competition with the key enzymes responsible for the respective metabolic reaction steps. The identification of a priori unknown reaction kinetics is often a critical task due to the non-linearity and (over-) parameterization of the model equations introduced to account for all the possible modulation phenomena. The contribution of this paper is to propose a general formulation of reaction kinetics, as an extension of the Michaelis-Menten kinetics, which allows limitation/activation and inhibition effects to be described with a reduced number of parameters. The versatility of the new model structure is demonstrated with application examples.

A mathematical multialveolar model has been developed which describes the mechanical behavior of the human ventilatory system in healthy subjects, under plethysmograph test conditions. It is based on the morphometric scheme of Weibel (1989) and uses the equations described by Pedley (1970) for modeling the airflow resistance. The 23 airways generations are grouped in four different levels on the basis of similar dimensions and mechanical properties. The dynamic effects of the changes in lung volume and transmural pressure on airway dimensions have been incorporated. In this first approach, the upper airways model is simplified and based on Rohrer's equation. The simulation results obtained from this model allow the authors to explain and retrieve global parameters available in the usual medical literature and obtained in healthy subjects during clinical tests. >

A model of the larynx, based on the analogy between the laryngeal channel and a constriction in a pipe, was developed by integrating the actual movements of the vocal cords during the quiet respiratory cycle. The model allows one to simulate and explain (1) the shape (tilted 8 with counterclockwise sign and cycle aperture) of the upper airway pressure-flow diagram, (2) the asymmetry between inspiratory and expiratory phases and (3) the variation of upper airway resistance with gas mixture.

Presents an approach to the design of a fuzzy supervisor for PID controllers that are used for controlling nonlinear systems. In this approach, the design is based on an output performance criterion, namely a response with a minimum settling time and without overshoot, whatever the operating conditions may be. The application used for a demonstration is a three-tank system where the connections between the tanks and the leakage in each tank are simultaneously taken into account (a MIMO system). According to the proposed approach, two fuzzy PI supervisors are designed in order to modify the parameters of two PI controllers online. The implementation of this type of control in the simulator of the three-tank system model confirms, through the simulation results, that the output performances are reached whatever the set-points, the configuration and the initial water levels in the three tanks may be.

The anti-synthetase syndrome comprises the association of an inflammatory myopathy (polymyositis, dermatomyositis), interstitial pneumonitis, skin lesions characteristic of "mechanics hands", Raynaud's phenomena, inflammatory polyarthritis and, at the biological level, antinuclear antibodies known as anti-synthetases. We report our observations of two patients, one with a typical anti-synthetase syndrome and one with an incomplete form. Two men aged 49 and 47 presented with increasing dyspnoea upon effort, muscular weakness, arthralgia, bilateral pulmonary crackles and, in the first case, typical hairless skin lesions. In both cases the chest x-rays and CT scans confirmed the presence of interstitial lesions, predominantly in the lower lobes. Lung function tests showed a restrictive pattern with reduced gas transfer. At the biological level both patients presented an inflammatory picture with elevated muscle enzymes and anti-Jo-1 antibodies. Immuno-suppressive treatment with cortico-steroids and cyclophosphamide lead to a symptomatic improvement, regression of the radiological changes and improvement in the measurements of pulmonary function.

A 28-year-old native Romanian homeless man presented to emergency department with two episodes of hemoptysis (estimated 300 ml) in the previous three days. For about two months he had been suffering from a dry cough with concurrent right-sided chest pain, asthenia, weight loss and a slight fever. Clinical examination revealed crepitations over the right lung fields. He was hemodynamically stable and no sign of respiratory distress was detected. Blood tests revealed a high CRP (72 mg/l).

Detailed first-principle models of grinding processes, while very satisfactory for simulation purposes, are not well suited for the development of control schemes due to their high level of complexity. In this study, a low-order model describing the time evolution of the particle distribution in a few size intervals is proposed. Using a maximum-likelihood approach, the model is identified and its good agreement with a detailed first-principle model is demonstrated. The model development and identification procedure are illustrated with a fed-batch grinding process. Finally, new control objectives, expressed in terms of the model state variables, are discussed.

In recent years, neural networks have attracted much attention for their potential to address a number of difficult problems in modelling and controlling nonlinear dynamic systems, especially in (bio) chemical engineering. The objective of this paper is to review some of the most widely used approaches to neural-network-based modelling, including plain black box as well as hybrid neural network — first principles modelling. Two specific application examples are used for illustration purposes: a simple tank level-control system is studied in simulation while a challenging bioprocess application is investigated based on experimental data. These applications allow some original concepts and techniques to be introduced.

Spiral or helical angioscanography for the positive or differential diagnosis of pulmonary emboli has become an emerging technique but remains poorly practised and has been little assessed scientifically. The optimal conditions to perform the test should be understood. The physician should appreciate in view of a large choice of parameters, the diagnostic value of the result and its reliability proximally and distally. Pulmonary angiography is only indicated when the angioscanography is negative according to the degree of clinical and paraclinical suspicion. Angiography magnetic resonance imaging is a diagnostic test full of promise which does not yet have its place in routine practice.

Mediastinal aneurysms of the bronchial arteries are uncommon abnormalities with potentially fatal hemorrhagic complications. Their diagnosis is usually made by angiography in emergency situations but computed tomography (CT) scan may depict them in asymptomatic patients. We describe the CT appearance of such an aneurysm detected as an incidental finding in a patient with bleeding bronchiectasis.

Chronic pulmonary interstitial fibrosis is the most frequent respiratory manifestation in systemic sclerosis, occurring in 80% of cases. It remains a severe complication of the disease and is the primary cause of mortality related to respiratory insufficiency in 20 to 60% of cases.The date of onset of interstitial lung disease remains undetermined, and only in rare cases does it reveal the presence of systemic sclerosis. The clinical signs are only observable at a later stage, when at least 50% of the lung parenchyma is affected. The methods of choice adopted for early diagnosis of this disease are high resolution computed tomography and pulmonary functional investigations; they should be carried out during the preliminary investigation and at follow-up once a year. Moreover, high resolution computed tomography also provides prognostic data, for there is a correlation between the type of lesion and its severity as determined by high resolution computed tomography and by histological findings. The value of other methods of investigation, in particular bronchoalveolar lavage, has not yet been clearly established. The association of cyclophosphamide and corticoids is currently being evaluated (indications, administration modalities, duration), and this combination may be the most effective treatment.Interstitial lung disease is one of the major causes of morbidity and mortality in systemic sclerosis. Early diagnosis and management of this disease is therefore of utmost importance.

The replacement of arteries with purely synthetic vascular prostheses often leads to the failure of such reconstructions when small-diameter or low-flow locations are concerned, due in part to the thrombogenicity of the internal graft surface. In order to improve long-term patency of these grafts, the concept of endothelial cell seeding has been suggested because this metabolically active endothelial surface plays major roles in preventing in vivo blood thrombosis and because vascular grafts placed in humans do not spontaneously form an endothelial monolayer whereas they do in animal models. The composite structure resulting from the combination of biologically active cells to prosthetic materials thus creates more biocompatible vascular substitutes. To achieve endothelialization of synthetic vascular grafts, previous efforts aimed at "one-stage" procedure (adding autologous endothelial cells to the graft at the time of implantation) in the 1980's seemed clinically feasible but results of reported clinical trials were controversial and mostly disappointing. An alternative method is an in vitro complete and preformed endothelial lining at the time of implantation: the "two-stage" procedure which implies harvest and culture of autologous endothelial cells. Up to date, the latter approach demonstrated its superiority in terms of significantly increased patency of the grafts that underwent endothelialization eight years earlier.

The present work deals with new observations made on a grinding plant of CBR (Mons, Belgium), which reveal an unstable behavior of the process due to the classifier. In particular, the influence of the flow rate entering the classifier is highlighted. The dynamic simulator developed and validated in a previous study is extended to include a new model of first generation classifiers and now reproduces the instability. Practically, the instability makes this process difficult to control. A new control structure has been proposed, tested in simulation and its implementation on the plant offers more efficiency and robustness.

Learning, i.e., estimation of weights and biases in neural networks, involves the minimization of a quadratic error criterion, a problem which is usually solved using backpropagation algorithms. This study, which is essentially experimental, aims at assessing the potential of first- and second-order simultaneous perturbation stochastic approximation (SPSA) algorithms to handle this minimization problem. To this end, several application examples in identification and control of nonlinear dynamic systems are presented. Test results, corresponding to training of neural networks possessing different structures and sizes, are discussed in terms of efficiency, accuracy, ease of use (parameter tuning), and implementation.

AN UPCOMING PUBLIC HEALTH PROBLEM: There has been a considerable focus on osteoporosis in men recently. Bone mass is high in men who have larger bones than women. The frequency of fractures is also higher due to post-trauma lesions. Femoral neck fractures have also increased over the last few years although the F/M ratio remains about 2.8. Overall, there is a trend towards an increased incidence of masculine osteoporosis (and vertebral fractures) due to population aging. FAVORING FACTORS IN MEN: The most important factors are hypoandrogenism, hypoestrogenism (pre or post-puberty), the alcohol-smoking association, malnutrition, lack of sun exposure and chronic liver disease. Other causes of osteoporosis (hyperthyroidism, Cushing's disease, hemochromatosis, gastrectomy, inflammatory rheumatic disease, tubulopathy, hypercalciuria and iatrogenic causes) should also be taken into consideration. PRETHERAPY WORK-UP: All the different possible etiologies should be investigated. Therapeutic protocols should provide hormone replacement when required, withdrawal of causal drugs, better nutrition and reduced alcohol and tobacco use.

Based on system analysis and experimental data, a dynamic model of a closed-loop cement grinding circuit, which consists of a mixed set of algebraic and partial differential equations, is developed and validated. The model equations are solved numerically using the method of lines and the resulting simulation program is used to gain some insight into the process dynamics and to design and compare control loops to achieve product specifications. The influence of the model nonlinearities, which are related to the dependency of the rates of breakage on the mill hold-up, is highlighted. In particular, this nonlinearity introduces a strong coupling between PI control loops using the fresh feed flow rate and the louver position of the classifier as manipulated variables. Several variations of this basic control scheme are thoroughly analyzed, and the necessity of an efficient mill flow rate control for the stability of the fineness control loop is demonstrated.

This paper focuses on modeling of an industrial cement grinding circuit using physical arguments and experimental data. The resulting "gray-box" model, which consists in a mixed set of algebraic and partial differential equations, can be used to gain some insight into the process dynamics and design control loops to achieve product specifications. Several multivariable control schemes using the feed rate and the classifier speed as manipulated variables, and the circulating material flow rates and/or the fineness of the product as controlled variables, respectively, are compared and the influence of disturbances, i.e., variations in the material grindability, is investigated.

Using two new cases and 70 case reports in the literature as a starting point, the authors focus on the Weismann-Netter-Stuhl syndrome. Weismann-Netter and Stuhl reported the first cases of tibioperoneal diaphyseal toxopachyosteosis in 1954. This syndrome is defined as an anomaly of the diaphyseal part of both tibiae and fibulae with posterior cortical thickening and anterior-posterior bowing. This anomaly is usually bilateral and symmetrical, and patients are therefore short in stature. The thickening of the fibula is true "tibialisation" and "is the main feature and the only feature confirming diagnosis". Routine laboratory investigations showed no abnormalities in the two new cases. The authors specify the limits encountered in classifying this anomaly and discuss the degree to which this anomaly is an entity unto itself when compared with rickets sequelae.

We report the discovery of a new gravitational lens (GL) candidate for the quasar J03.13 (z = 2.55). The mean angular separation and magnitude difference between the A & B QSO images are found to be 0.84″ and 2.10 mag, respectively. A spatially unresolved medium resolution spectrum of J03.13 shows intervening absorption line systems at z = 2.34 and z = 1.085. The latter one is possibly associated with a σ 206 km/s lens galaxy.

Direct CCD images of the gravitationally lensed BAL quasar H1413+117 (Bessel B, V, R, I; Gunn r and i), obtained during 1989−1994 in the framework of photometric monitorings at ESO and with the NOT, have been carefully (re-)analyzed. Simultaneous fitting of 4 PSFs, fixing the relative positions of components B, C and D with respect to A, has been achieved successfully. The relative light curves of the 4 lensed QSO images, with respect to a stable nearby comparison star, confirm the general trend already presented by Arnould et al. (1993). The amplitude of the light curves is found to be about 0.5 magnitude, peak-to-peak in the V filter. The four lensed components display brightness variations quasi-simultaneously and in parallel. In addition to these intrinsic light variations due to the source, we find that component D shows extra light variations with respect to the other components. These are very likely caused by micro-lensing.

Having observed homozygotic identical twin brothers suffering simultaneously from anaplastic bronchial cancer leading rapidly to death in both cases, the authors assessed the frequency of such cases. The available literature failed to reveal any identical observations, although four cases of twins suffering from bronchial cancer featuring different histologies (three epidermoidal and one bronchiolar-alveolar) were noted. Statistics show that, in the area where the observed twins were living, anaplastic cancer occurs each year in 0.39% of 53-year-old men. The case of these twins therefore supports the idea of the role of genetic factors in the determination of bronchial cancer.

The fundamental principles of computed tomography (CT), its clinical applications and costs are presented followed by the indications and results in diseases of the mediastinum, the oesophagus, heart and great vessels, and the lung and pleura. The CT scan can give the precise localization and density of mediastinal tumours and be used to distinguish thymomas, goiters, lymph nodes, lymphomas, neurinomas and different bronchogenic and pleuropericardial cystic formations. The operability of oesophageal cancer can also be determined. In cardiovascular diseases, the CT scan is particularly useful to identify inborn anomalies, aneurysms, aortic dissection or caval compression or thrombus formation. In lung diseases, the indications for a CT scan are particularly important in bronchopulmonary cancer, tuberculosis, bronchopathies and chronic lung diseases. In bronchogenic cancer, for example, the CT scan is not only a major diagnostic tool but is also particularly useful in determining the prognosis and for following the effectiveness of treatment. The CT scan can be used to identify both effusions of liquid and gas as well as pleural reactions producing thick membranes of importance for both aetiology and later follow-up. Bronchectasis can be identified on serial sections where the degree of extension can be measured. CT scan is also indicated in patients with emphysema, both for evaluating extension and follow-up. Finally the indications and contraindications for interventional computed tomography, particularly in guiding needle biopsies, is presented.

Scimitar syndrome is characterized by an anomalous pulmonary vein draining into the inferior vena cava and visible roentgenographically as a crescentic shadow of vascular density along the right border of the cardiac silhouette. The aim of this study is to report four cases associated with anatomical or functional absence of the right pulmonary artery.Diagnosis of scimitar syndrome had been made in 4 patients aged 3, 10, 23 and 33 years. Pulmonary scintigraphy and/or CT scan detected the scimitar syndrome and the type of pulmonary and systemic vascularization. In all cases, the vascularization of the right lung did not originate from the pulmonary artery trunk but was supplied by systemic vessels arising from the abdominal aorta. The right pulmonary artery was vascularized a retro, against the stream, by the systemic vessels (two cases); alternatively, circulation into the right pulmonary artery resulted directly from the systemic vessels, this pulmonary artery being anatomically absent (two cases). Pulmonary arterial pressures were normal in all four cases and functional tolerance was good in three cases; repeated and severe hemoptysis required right pneumonectomy in the last patient.These four cases are compared to six other similar cases in the literature. Elegant and non invasive methods are now disposable to detect such a syndrome and to assess the type of pulmonary vascularization.

New spectroscopic and photometric observations of WR22 are presented. High signal-to-noise digital spectra with high dispersion are used to improve the parameters of the orbit (P = 80.31 ±0.01 d), formerly determined on the basis of photographic spectra only. The intrinsic photometric variability of WR22 and recent observations of the eclipse are also discussed.