A framework for modelling the biomechanical behaviour of the human liver during breathing in real time using machine learning

Progress in biomechanical modelling of human soft tissue is the basis for the development of new clinical applications capable of improving the diagnosis and treatment of some diseases (e.g. cancer), as well as the surgical planning and guidance of some interventions. The finite element method (FEM) is one of the most popular techniques used to predict the deformation of the human soft tissue due to its high accuracy. However, FEM has an associated high computational cost, which makes it difficult its integration in real-time computer-aided surgery systems. An alternative for simulating the mechanical behaviour of human organs in real time comes from the use of machine learning (ML) techniques, which are much faster than FEM. This paper assesses the feasibility of ML methods for modelling the biomechanical behaviour of the human liver during the breathing process, which is crucial for guiding surgeons during interventions where it is critical to track this deformation (e.g. some specific kind of biopsies) or for the accurate application of radiotherapy dose to liver tumours. For this purpose, different ML regression models were investigated, including three tree-based methods (decision trees, random forests and extremely randomised trees) and other two simpler regression techniques (dummy model and linear regression). In order to build and validate the ML models, a labelled data set was constructed from modelling the deformation of eight ex-vivo human livers using FEM. The best prediction performance was obtained using extremely randomised trees, with a mean error of 0.07 mm and all the samples with an error under 1 mm. The achieved results lay the foundation for the future development of some real-time software capable of simulating the human liver deformation during the breathing process during clinical interventions.This work has been funded by the Spanish Ministry of Economy and Competitiveness (MINECO) through research projects TIN2014-52033-R and DPI2013-40859-R, both also supported by European FEDER funds. The authors acknowledge the kind collaboration of the personnel from the hospital involved in the research.Lorente, D.; Martínez-Martínez, F.; Rupérez Moreno, MJ.; Lago, MA.; Martínez-Sober, M.; Escandell-Montero, P.; Martínez-Martínez, JM.... (2017). A framework for modelling the biomechanical behaviour of the human liver during breathing in real time using machine learning. Expert Systems with Applications. 71:342-357. doi:10.1016/j.eswa.2016.11.037S3423577

Effects of patient recumbency position on neonatal chest EIT

This paper investigates the overlooked effects of the patient recumbency positions on one of the key clinically used parameters in chest electrical impedance tomography (EIT) monitoring – the silent spaces. This parameter could impact medical decisions and interventions by indicating how well each lung is being ventilated. Yet it is largely dependent on assumptions of prior model at the reconstruction stage and the closely linked region of interest (ROI) during the final calculations. The potential effect of switching recumbency modes on silent spaces as a results of internal organ movements and consequently changes in initial assumptions, has been studied. The displacement and deformations caused by posture changes from supine to lateral recumbent were evaluated via simulations considering the simultaneous gravity-dependent movement and/or deformations of heart, mediastinum, lungs and the diaphragm. The reliability of simulations was verified against reference radiography images of an 18-month-old infant in supine and decubitus lateral positions. Inspecting a set of 10 patients from age range of 1 to 2 years old revealed improvements of up to 30% in the silent space parameters when applying posture consistent amendments as opposed to fixed model/ROI to each individual. To minimize the influence of image reconstruction technique on the results two different EIT reconstruction algorithms were implemented. The outcome emphasized the importance of including recumbency situation during chest EIT monitoring within the considered age range

Effects of Patient Recumbency Position on Neonatal Chest EIT

This paper investigates the overlooked effects of the patient recumbency positions on one of the key clinically used parameters in chest electrical impedance tomography (EIT) monitoring – the silent spaces. This parameter could impact medical decisions and interventions by indicating how well each lung is being ventilated. Yet it is largely dependent on assumptions of prior model at the reconstruction stage and the closely linked region of interest (ROI) during the final calculations. The potential effect of switching recumbency modes on silent spaces as a results of internal organ movements and consequently changes in initial assumptions, has been studied. The displacement and deformations caused by posture changes from supine to lateral recumbent were evaluated via simulations considering the simultaneous gravity-dependent movement and/or deformations of heart, mediastinum, lungs and the diaphragm. The reliability of simulations was verified against reference radiography images of an 18-month-old infant in supine and decubitus lateral positions. Inspecting a set of 10 patients from age range of 1 to 2 years old revealed improvements of up to 30% in the silent space parameters when applying posture consistent amendments as opposed to fixed model/ROI to each individual. To minimize the influence of image reconstruction technique on the results two different EIT reconstruction algorithms were implemented. The outcome emphasized the importance of including recumbency situation during chest EIT monitoring within the considered age range

Some aspects of the human body's hydraulics

This paper presents some aspects related to the human body's hydraulics in the desire to make readers aware of how to maintain all the blood vessels of the human body in order to maintain the entire healthy, functional, young, vigorous circulatory system for a while the longest possible. The problem is complex because it has to be viewed from all points of view and not only as an isolated system in the body, having aspects of feedback on the whole physiopathology belonging to the human body. The highly circulating system needs permanent maintenance. Self-maintenance is done through various physiological mechanisms tightly linked to each other, including the lymphatic, digestive, renal, lung, nervous, glandular system… It is not possible to completely separate the physiology of a system from the other adjacent systems because they all work synergistically, being permanently controlled by the central and peripheral nervous system

A 3D multi-scale skeletal muscle model to predict active and passive responses. Application to intra-abdominal pressure prediction

Computational models have been used extensively to study the behavior of skeletal muscle structures, however few of these models are able to evaluate their 3D active response using as input experimental measurements such as electromyography. Hence, improving the activation mechanisms in simulation models can provide interesting and useful achievements in this field. Therefore, the purpose of this paper was to develop a multi-scale chemo-mechanical material model to consider the active behavior of skeletal muscle in 3D geometries. The model was used to investigate the response of abdominal muscles which represent a challenging scenario due to their complex geometry and anatomical conditions. Realistic muscle geometries and other tissues of the human abdomen, including transverse abdominis (TA), internal oblique (IO), external oblique (EO), rectus abdominis (RA), rectus sheath (RSH), linea alba (LA) and aponeurosis (APO) were considered. Since the geometry of these tissues was obtained from magnetic resonance images, an iterative algorithm was implemented to find the initial stress state that achieve the equilibrium of them with the intra-abdominal pressure. In order to investigate the functionality of the proposed model, the increase of intra-abdominal pressure was calculated during cough in the supine position while the Ca2+ signal for activating the muscles was set in regard to experimentally recorded electrical activity from previous studies. The amount of intra-abdominal pressure calculated by the model is consistent with reported experimental results. This model can serve as a virtual laboratory to analyze the role of the abdominal wall components in different conditions, such as the performance of meshes used for repairing hernia defects

Aerospace medicine and biology: A continuing bibliography with indexes (supplement 275)

This bibliography lists 321 reports, articles, and other documents introduced into the NASA scientific and technical information system in August 1985

Computer-Assisted Liver Surgery: from preoperative 3D patient modelling to peroperative guidance

La chirurgie représente le meilleur taux de survie pour les cancers hépatiques. Le traitement d’images médicales peut apporter une importante amélioration dans la prise en charge en guidant le geste chirurgical. Nous présentons ici une nouvelle procédure chirurgicale assistée par ordinateur incluant la modélisation 3D préopératoire du patient, suivie par une planification chirurgicale virtuelle et finalisée par un guidage peropératoire réalisé par réalité augmentée (RA). Les premières évaluations incluant des applications cliniques valident le bénéfice attendu. La prochaine étape consistera à automatiser le système de réalité augmentée peropératoire par le développement d’une salle d’opération hybride.Surgery has the best survival rate in hepatic cancer. However, such interventions cannot be undertaken for all patients as the eligibility rules for liver surgery lack accuracy and may include many exceptions. Medical image processing can lead to a major improvement of patient care by guiding the surgical gesture. We present here a new computer-assisted surgical procedure including preoperative 3D patient modelling, followed by virtual surgical planning and finalized by intraoperative computer guidance through the use of augmented reality. First evaluations including the clinical application validate the awaited benefit. The next step will consist in automating the intraoperative augmented reality system thanks to the development of a Hybrid surgical OP-room

Preclinical MRI of the kidney : methods and protocols

This Open Access volume provides readers with an open access protocol collection and wide-ranging recommendations for preclinical renal MRI used in translational research. The chapters in this book are interdisciplinary in nature and bridge the gaps between physics, physiology, and medicine. They are designed to enhance training in renal MRI sciences and improve the reproducibility of renal imaging research. Chapters provide guidance for exploring, using and developing small animal renal MRI in your laboratory as a unique tool for advanced in vivo phenotyping, diagnostic imaging, and research into potential new therapies. Written in the highly successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Cutting-edge and thorough, Preclinical MRI of the Kidney: Methods and Protocols is a valuable resource and will be of importance to anyone interested in the preclinical aspect of renal and cardiorenal diseases in the fields of physiology, nephrology, radiology, and cardiology. This publication is based upon work from COST Action PARENCHIMA, supported by European Cooperation in Science and Technology (COST). COST (www.cost.eu) is a funding agency for research and innovation networks. COST Actions help connect research initiatives across Europe and enable scientists to grow their ideas by sharing them with their peers. This boosts their research, career and innovation. PARENCHIMA (renalmri.org) is a community-driven Action in the COST program of the European Union, which unites more than 200 experts in renal MRI from 30 countries with the aim to improve the reproducibility and standardization of renal MRI biomarkers

148. Carbon Nanotubes

Carbon nanotubes (CNTs) can be seen as graphene sheets rolled to form cylinders. CNTs may be categorised as single- (SWCNT) or multi-walled (MWCNT). Due to the small size, the number of particles as well as the surface area per mass unit is extremely high. CNTs are highly diverse, differing with respect to e.g., diameter, length, chiral angles, chemical functionalisation, purity, stiffness and bulk density. Today, CNTs are utilised primarily for the reinforcement of composite polymers, but there is considerable potential for other applications. The rapidly growing production and use of CNTs increases the risk for occupational exposure. Since CNTs in bulk form are of very low density and much dust is produced during their handling, exposure by inhalation appears to represent the greatest potential risk in the work place. However, most work place measurements involved sampling periods that are too short, varying sampling techniques and non-specific analytical methods. CNTs may be absorbed via inhalation and ingestion. Systemic uptake via the skin has not been demonstrated. Human toxicity data on CNTs are lacking and interpretation of animal studies is often problematic since the physical properties and chemical composition are diverse, impurities may be present and data are sometimes omitted. Because of the physical similarities between asbestos and CNTs, it can be suspected that the latter may also cause lung fibrosis, mesothelioma and lung cancer following inhalation. Intraperitoneal and intrascrotal administration of CNTs causes mesothelioma in animals, but no inhalation carcinogenicity studies have been conducted. Thus, it is too early conclude whether CNTs cause mesothelioma and lung cancer in humans. Both SWCNTs and MWCNTs cause inflammation and fibrosis in the lungs of relevant animal types and for MWCNTs these effects are also seen in the pleura. For instance, minimal histiocytosis and mild granulomatous inflammation in the lungs and lung-draining lymph nodes have been observed in rats exposed for 13 weeks to 0.1 mg/m3 MWCNTs (lowest observed adverse effect level, LOAEL), with more pronounced inflammation in both mice and rats at higher doses. Thus, inflammatory responses in the lungs may be considered as the critical effect. However, the LOAEL of CNTs should be interpreted cautiously, since their toxicity is likely to vary widely, depending on the structure and physicochemical properties, as well as the contribution from non-carbon components. It is also uncertain which dose metric (e.g., mass, number or surface area per air volume unit) is most appropriate. Some studies indicate that longer straight CNTs evoke more pronounced biological effects than shorter or tangled fibres

Preclinical MRI of the Kidney

This Open Access volume provides readers with an open access protocol collection and wide-ranging recommendations for preclinical renal MRI used in translational research. The chapters in this book are interdisciplinary in nature and bridge the gaps between physics, physiology, and medicine. They are designed to enhance training in renal MRI sciences and improve the reproducibility of renal imaging research. Chapters provide guidance for exploring, using and developing small animal renal MRI in your laboratory as a unique tool for advanced in vivo phenotyping, diagnostic imaging, and research into potential new therapies. Written in the highly successful Methods in Molecular Biology series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls. Cutting-edge and thorough, Preclinical MRI of the Kidney: Methods and Protocols is a valuable resource and will be of importance to anyone interested in the preclinical aspect of renal and cardiorenal diseases in the fields of physiology, nephrology, radiology, and cardiology. This publication is based upon work from COST Action PARENCHIMA, supported by European Cooperation in Science and Technology (COST). COST (www.cost.eu) is a funding agency for research and innovation networks. COST Actions help connect research initiatives across Europe and enable scientists to grow their ideas by sharing them with their peers. This boosts their research, career and innovation. PARENCHIMA (renalmri.org) is a community-driven Action in the COST program of the European Union, which unites more than 200 experts in renal MRI from 30 countries with the aim to improve the reproducibility and standardization of renal MRI biomarkers