Multidetector row CT for imaging the paediatric tracheobronchial tree.
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The introduction of multidetector row computed tomography (MDCT) scanners has altered the approach to imaging the paediatric thorax. In an environment where the rapid acquisition of CT data allows general hospitals to image children instead of referring them to specialist paediatric centres, it is vital that general radiologists have access to protocols appropriate for paediatric applications. Thus a dramatic reduction in the delivered radiation dose is ensured with optimal contrast bolus delivery and timing, and inappropriate repetition of the scans is avoided. This article focuses on the main principles of volumetric CT imaging that apply generically to all MDCT scanners. We describe the reconstruction techniques for imaging the paediatric thorax and the low-dose protocols used in our institution on a 16-slice detector CT scanner. Examples of the commonest clinical applications are also given. (+info)
Resolution of pulmonary multiplanar reconstruction images from 0.5-mm theoretical isotropic data: a fundamental study using an inflated and fixed lung specimen.
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The aim of the present study was to define the resolution of multiplanar reconstruction (MPR) of the lung from "theoretical isotropic data." Using inflated and fixed lung specimens of the pig placed in the chest wall phantom, 0.5-mm isotropic data were obtained with 2 different helical pitches: 1:7 (high-quality mode) or 1:13, (high-speed mode), and 2 different tube currents: 250 mAs (high-tube-current mode) or 100 mAs (low-tube-current mode), with or without overlapping reconstruction. MPRs were created from these axial data. The diameter of the smallest visible pulmonary artery and bronchi of these CT images were measured on the corresponding slices of the specimen. The high-speed and low-tube-current mode significantly degraded the image quality due to increased noise. The smallest visible pulmonary artery and bronchus resolved on MPRs from axial-spiral data with 0.5-mm collimation were approximately 100 micrometer and 1,000 micrometer in diameter, respectively. In conclusion, helical pitch and tube current influence the resolution of MPR of the lung. (+info)
Airway strain during mechanical ventilation in an intact animal model.
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RATIONALE: Mechanical ventilation with large tidal volumes causes ventilator-induced lung injury in animal models. Little direct evidence exists regarding the deformation of airways in vivo during mechanical ventilation, or in the presence of positive end-expiratory pressure (PEEP). OBJECTIVES: To measure airway strain and to estimate airway wall tension during mechanical ventilation in an intact animal model. METHODS: Sprague-Dawley rats were anesthetized and mechanically ventilated with tidal volumes of 6, 12, and 25 cm(3)/kg with and without 10-cm H(2)O PEEP. Real-time tantalum bronchograms were obtained for each condition, using microfocal X-ray imaging. Images were used to calculate circumferential and longitudinal airway strains, and on the basis of a simplified mathematical model we estimated airway wall tensions. MEASUREMENTS AND MAIN RESULTS: Circumferential and longitudinal airway strains increased with increasing tidal volume. Levels of mechanical strain were heterogeneous throughout the bronchial tree. Circumferential strains were higher in smaller airways (less than 800 mum). Airway size did not influence longitudinal strain. When PEEP was applied, wall tensions increased more rapidly than did strain levels, suggesting that a "strain limit" had been reached. Airway collapse was not observed under any experimental condition. CONCLUSIONS: Mechanical ventilation results in significant airway mechanical strain that is heterogeneously distributed in the uninjured lung. The magnitude of circumferential but not axial strain varies with airway diameter. Airways exhibit a "strain limit" above which an abrupt dramatic rise in wall tension is observed. (+info)
Chest computed tomography with multiplanar reformatted images for diagnosing traumatic bronchial rupture: a case report.
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INTRODUCTION: Unnoticed bronchial injury during the early stage of resuscitation of multiple trauma is not rare and increases mortality and morbidity. METHODS: Three-dimensional reconstruction of the airways using a workstation connected to a multidetector chest computed tomography (CT) scanner may change the diagnostic strategy in patients with blunt chest trauma with clinical signs evocative of bronchial rupture. RESULTS: In this case report of a young motor biker, a complete disruption of the intermediary trunk was first misdiagnosed using standard chest helical CT and bronchoscopy. Postprocessing procedures including three-dimensional extraction of the tracheobronchial tree were determinants for establishing the diagnosis, and emergent surgical repair was successfully performed. Follow-up using CT with three-dimensional reconstructions evidenced a bronchial stenosis located at the site of the rupture. CONCLUSION: The present study demonstrates the potential interest of performing three-dimensional reconstructions by extraction of the tracheal-bronchial tree in patients with severe blunt chest trauma suspected of bronchial rupture. (+info)
Assessment of bronchial wall thickness and lumen diameter in human adults using multi-detector computed tomography: comparison with theoretical models.
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A thickened bronchial wall is the morphological substratum of most diseases of the airway. Theoretical and clinical models of bronchial morphometry have so far focused on bronchial lumen diameter, and bronchial length and angles, mainly assessed from bronchial casts. However, these models do not provide information on bronchial wall thickness. This paper reports in vivo values of cross-sectional wall area, lumen area, wall thickness and lumen diameter in ten healthy subjects as assessed by multi-detector computed tomography. A validated dedicated software package was used to measure these morphometric parameters up to the 14th bronchial generation, with respect to Weibel's model of bronchial morphometry, and up to the 12th according to Boyden's classification. Measured lumen diameters and homothety ratios were compared with theoretical values obtained from previously published studies, and no difference was found when considering dichotomic division of the bronchial tree. Mean wall area, lumen area, wall thickness and lumen diameter were then provided according to bronchial generation order, and mean homothety ratios were computed for wall area, lumen area and wall thickness as well as equations giving the mean value of each parameter for a given bronchial generation with respect to its value in generation 0 (trachea). Multi-detector computed tomography measurements of bronchial morphometric parameters may help to improve our knowledge of bronchial anatomy in vivo, our understanding of the pathophysiology of bronchial diseases and the evaluation of pharmacological effects on the bronchial wall. (+info)
Primary ciliary dyskinesia: considerations regarding six cases of Kartagener syndrome.
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Primary ciliary dyskinesia (PCD), previously known as immotile cilia syndrome, is an autosomal recessive hereditary disease that includes various patterns of ciliary ultrastructural defects. The most serious form is Kartagener syndrome (KS), which accounts for 50% of all cases of PCD. The incidence of PCD ranges from 1:20,000 to 1:60,000. Since PCD causes deficiency or even stasis of the transport of secretions throughout the respiratory tract, it favors the growth of viruses and bacteria. As a result, patients have lifelong chronic and recurrent infections, typically suffering from bronchitis, pneumonia, hemoptysis, sinusitis, and infertility. Bronchiectasis and other chronic conditions infections can be the end result of the irreversible bronchial alterations, leading to chronic cor pulmonale and its consequences. Only half of the patients affected by PDC present all of the symptoms, a condition designated complete KS, compared with incomplete KS, typically defined as cases in which situs inversus does not occur. The diagnosis is made clinically and confirmed through transmission electron microscopy. Since there is no specific therapy for PCD, it is recommended that, upon diagnosis, secondary infections be treated with potent antibiotics and prophylactic interventions be implemented. In this paper, we report six cases of PCD (five cases of complete KS and one case of KS) and review the related literature, focusing on the diagnostic, therapeutic and clinical aspects of this disease. (+info)
Foreign body aspiration in a boy with Prader-Willi Syndrome.
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A five-year-old boy presented with progressive weight gain with effort intolerance and nocturnal symptoms suggesting obstructive sleep apnoea. A clinical diagnosis of Prader-Willi Syndrome was made. As the initial radiography and computed tomography suggested a foreign body, bronchoscopy was done under general anaesthesia and impacted peanuts were removed from the left main bronchus. His symptoms resolved instantly and the patient was asymptomatic at six months follow-up. This report highlights the need to consider foreign body aspiration as a cause for dyspnoea in children with Prader-Willi Syndrome. The report also focuses on the need to adopt strategies that prevent foreign body aspiration and choking in patients with Prader- Willi Syndrome. (+info)
Bifurcation model for characterization of pulmonary architecture.
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