A hybrid patient-specific biomechanical model based image registration method for the motion estimation of lungs

This paper presents a new hybrid biomechanical model-based non-rigid image registration method for lung motion estimation. In the proposed method, a patient-specific biomechanical modelling process captures major physically realistic deformations with explicit physical modelling of sliding motion, whilst a subsequent non-rigid image registration process compensates for small residuals. The proposed algorithm was evaluated with 10 4D CT datasets of lung cancer patients. The target registration error (TRE), defined as the Euclidean distance of landmark pairs, was significantly lower with the proposed method (TRE = 1.37 mm) than with biomechanical modelling (TRE = 3.81 mm) and intensity-based image registration without specific considerations for sliding motion (TRE = 4.57 mm). The proposed method achieved a comparable accuracy as several recently developed intensity-based registration algorithms with sliding handling on the same datasets. A detailed comparison on the distributions of TREs with three non-rigid intensity-based algorithms showed that the proposed method performed especially well on estimating the displacement field of lung surface regions (mean TRE = 1.33 mm, maximum TRE = 5.3 mm). The effects of biomechanical model parameters (such as Poisson’s ratio, friction and tissue heterogeneity) on displacement estimation were investigated. The potential of the algorithm in optimising biomechanical models of lungs through analysing the pattern of displacement compensation from the image registration process has also been demonstrated

Выбор конечноэкспираторного давления при механической респираторной поддержке (обзор)

Endexpiratory pressure remains one of the few parameters of mechanical respiratory support whose val ues have not been strictly regulated using the evidencebased approach. The absence of «gold standard» for endexpiratory pressure optimization together with its obvious significant contribution to the efficiency and safety of respiratory support has driven the search for the optimal method of choosing its values for several decades.Aim of the review: to identify the optimal methods for determining the values of endexpiratory pressure based on the analysis of its positive and negative effects in the used strategies of mechanical respiratory support.Material and methods. We analyzed 165 papers from the PubMed, Scopus, and RSCI databases of medical and biological publications. Among them we selected 86 sources that most completely covered the following subjects: respiratory support, endexpiratory pressure, recruitment, ventilationperfusion relationships, metabolography, and gas analysis.Results. We outlined the main positive and negative effects of the endexpiratory pressure with regard to both lung biomechanical characteristics and pulmonary perfusion. The evolution of views on the methods of determining optimal values of the endexpiratory pressure was reviewed with the emphasis on a certain «fix ation» of the scientific community in recent decades concerning the opening of the alveoli. The promising techniques based on the analysis of the diffusion capacity of the lungs were presented.Conclusion. Focusing on mechanical lung opening prevents the scientific community from advancing in the optimization of the endexpiratory pressure. Dynamic assessment of pulmonary diffusion efficiency pro vides a new perspective on the issue, offering additional ways to the development of «gold standard».Конечно-экспираторное давление остается сегодня одним из немногих параметров механической респираторной поддержки, значения которых не подверглись строгой регламентации с позиций научно-доказательной медицины. Отсутствие «золотого стандарта» оптимизации конечно экспираторного давления в совокупности с очевидным значимым вкладом в эффективность и безопасность респираторной поддержки заставляет в течение десятилетий продолжать поиск оптимального метода выбора его значений.Цель обзора. Выявление оптимальных методов определения значений конечноэкспираторного давления на основе анализа его положительных и негативных эффектов в применяемых стратегиях механической респираторной поддержки.Материалы и методы. Анализировали 165 научных работ из баз данных медицинских и биологических публикаций PubMed, Scopus, РИНЦ. Из них отобрали 86 источников, наиболее полно отражающих информацию по следующим разделам: респираторная поддержка, конечно-экспираторное давление, рекрутмент, вентиляционно-перфузионные отношения, метаболография, газоанализ.Результаты. Сформулировали основные положительные и негативные эффекты конечно-экспираторного давления в отношении как биомеханических характеристик легких, так и легочной пер фузии. Провели анализ эволюции взглядов на методики определения оптимальных значений конечно-экспираторного давления, в котором сделали акцент на некую «зацикленность» научного сообщества в последние десятилетия в отношении раскрытия альвеол. Привели перспективные методики, основанные на анализе диффузионного потенциала легких.Заключение. Фокусировка внимания на механическом раскрытии легких не позволяет продвинуться научному обществу в оптимизации конечно-экспираторного давления. Методы динамической оценки эффективности легочной диффузии позволяют взглянуть на проблему под новым углом, открывая дополнительные пути «золотого стандарта»

Protein Concentration Elevations in Mouse Lungs Following Sudden Transient Cephalad (+Gz) Acceleration

Laboratory and feral lineages of mice were subjected to cephalad (+GZ) accelerations, for 1.8 seconds, aboard a solid fuel rocket. Spectrophotometric analysis of bronchoalveolar lavage retrieved post launch revealed significant (p \u3c .001) elevations of protein in the lungs of experimental mice. Sudden transient imposition of a mean +GZ acceleration of 6.22 ± .47 (SD) G, at lift-off, may have induced hypervolemia of basilar pulmonary microvasculature with concomitant migration of fluid and protein from intravascular to juxta-alveolar perivascular compartments. Exudates may have entered bronchiolar airways subsequently gravitating toward alveoli

From Early Morphometrics to Machine Learning-What Future for Cardiovascular Imaging of the Pulmonary Circulation?

Imaging plays a cardinal role in the diagnosis and management of diseases of the pulmonary circulation. Behind the picture itself, every digital image contains a wealth of quantitative data, which are hardly analysed in current routine clinical practice and this is now being transformed by radiomics. Mathematical analyses of these data using novel techniques, such as vascular morphometry (including vascular tortuosity and vascular volumes), blood flow imaging (including quantitative lung perfusion and computational flow dynamics), and artificial intelligence, are opening a window on the complex pathophysiology and structure-function relationships of pulmonary vascular diseases. They have the potential to make dramatic alterations to how clinicians investigate the pulmonary circulation, with the consequences of more rapid diagnosis and a reduction in the need for invasive procedures in the future. Applied to multimodality imaging, they can provide new information to improve disease characterization and increase diagnostic accuracy. These new technologies may be used as sophisticated biomarkers for risk prediction modelling of prognosis and for optimising the long-term management of pulmonary circulatory diseases. These innovative techniques will require evaluation in clinical trials and may in themselves serve as successful surrogate end points in trials in the years to come

Distribution of Angiostrongylus vasorum and Crenosoma vulpis in red foxes (Vulpes vulpes) in Newfoundland, Canada

Angiostrongylus vasorum, the French heartworm, and Crenosoma vulpis, a lungworm, infect the pulmonary arteries and the bronchi and bronchioles, respectively, o f red foxes (Vulpes vulpes). Both are widespread in Europe, but within North America the distribution of A. vasorum is limited to the island of Newfoundland, Canada. During 2000-2002, 366 fox carcasses were collected from 6 regions o f the island. This study is unique in being the first large-scale survey of A. vasorum and C. vulpis in a natural fox population. Its objectives were to determine the precise distribution o f both parasites in Newfoundland and to examine the possibility of interaction between them. Crenosoma vulpis occurred in all 6 regions at an overall prevalence o f 87% and a mean intensity o f 230 ± 20.8 (mean ± S.E.). Young-of-the-year foxes had higher mean intensities (260 ± 39.4) than yearlings (91 ± 31.2) or adults (78 ± 41.1) (F[2, 153] = 11.07, p < 0.001). The intensity o f C. vulpis was not related to host sex, omental fat ratio, or body fat index. There was a weak positive relationship between number of adult worms and output of first-stage larvae in feces (r2 = 0.199, Ff[1,135] = 34.84, p < 0.001); larval output decreased with increasing fox age (F[2,127 ] = 18.99,p< 0.001). Angiostrongylus vasorum occurred only in the 3 southeast regions of the island; the Avalon Peninsula, the North East Coast, and the South Coast/Burin Peninsula. Its distribution may be limited by cold temperatures as it did not occur in areas where mean winter temperatures were lower than -4°C . The prevalence was 56% and mean intensity 72 ± 7.6. The number of adult worms did not differ with host age, sex, omental fat ratio, or body fat index. Although named the French heartworm, 88% of all A. vasorum were recovered from the pulmonary arteries while the remainder were in the right ventricle. However, 78% o f infected foxes had at least one worm in the right ventricle. Although the number of A. vasorum did not differ between the pulmonary arteries o f the left and right lobes (F[1, 164] = 1.70, p= 0.194), there were more worms in the arteries o f the posterior lobes (47 ± 5.4) than in the anterior (24 ± 2.5) (F[1, 161] = 13.39, p < 0.001). Also, there were no relationships between the number of A vasorum and larval output, heart weight ratio, or ventricular ratio. Although 40% of foxes from the A. vasorum positive regions had both A. vasorum and C. vulpis infections, there was no interaction between the two parasites (Gc[1] = 0.10). Furthermore, there was no linear relationship between the two parasites, and the mean intensity of each nematode did not differ between single and dual infections. Eight coyotes (Canis latrans) from Newfoundland were also examined. None had A. vasorum, but 38% had C. vulpis, although the mean intensity (16 ± 10.2) was lower than that in foxes

A quantitative estimation of regulation and transport limitations in the human cardiopulmonary system

The object of this dissertation is to quantitatively describe the regulation of some of the exchange processes within the human body. Conceptually this dissertation is divided into two sections. In the first section a macroscopic view was adopted to describe the overall regulation of the cardiovascular and respiratory systems. These overall system models were used as heuristic tools to gain an understanding of physiological behavior in micro-gravity. In the second section, a microscopic view was used to estimate the role played by the surfactant system of the lung in regulating the transfer of fluid across the pulmonary-capillary wall;The basis of the cardiovascular system model is the maintenance of arterial blood pressure homeostasis. Sub-models constituting the overall model are: the pressure-flow model, the heart action model, the controller model which describes short term-control, and the renal model which describes long term control and the regulation of total body water content. Model predictions show that incorporating the fluid shift from the lower to the upper part of the body in micro-gravity is sufficient to account for the cardiovascular changes occurring in micro-gravity;The respiratory model is concerned with the maintenance of a constant carbon dioxide level in the tissue and body fluids. The sub-models constituting the overall respiratory model are: the gas-exchange model, the mechanics model, and the controller model which determines the ventilation and cardiac output on the basis of arterial blood gas tensions. Simulation results show that pleural pressure homogeneity, increased lung diffusing capacity and decreased lung volume are sufficient to describe respiratory changes in micro-gravity;In the penultimate section the lung mechanics model is coupled with a model of fluid exchange across the pulmonary-capillary wall. The lung mechanics model estimates the influence of the surfactant system of the lung in controlling the interstitial space hydrostatic pressure while the fluid exchange model determines the influence of the interstitial space hydrostatic pressure in regulating fluid movement across the pulmonary-capillary wall. This model quantitatively estimates the influence of the surfactant alone in regulating fluid movement across the pulmonary-capillary wall

Acción del manitol sobre el pulmón en cirugía cardiaca con circulación extracorporea

Depto. de CirugíaFac. de MedicinaTRUEProQuestpu