Medical Images Encryption Based on Adaptive-Robust Multi-Mode Synchronization of Chen Hyper-Chaotic Systems

In this paper, a novel medical image encryption method based on multi-mode synchronization of hyper-chaotic systems is presented. The synchronization of hyper-chaotic systems is of great significance in secure communication tasks such as encryption of images. Multi-mode synchronization is a novel and highly complex issue, especially if there is uncertainty and disturbance. In this work, an adaptive-robust controller is designed for multimode synchronized chaotic systems with variable and unknown parameters, despite the bounded disturbance and uncertainty with a known function in two modes. In the first case, it is a main system with some response systems, and in the second case, it is a circular synchronization. Using theorems it is proved that the two synchronization methods are equivalent. Our results show that, we are able to obtain the convergence of synchronization error and parameter estimation error to zero using Lyapunov’s method. The new laws to update time-varying parameters, estimating disturbance and uncertainty bounds are proposed such that stability of system is guaranteed. To assess the performance of the proposed synchronization method, various statistical analyzes were carried out on the encrypted medical images and standard benchmark images. The results show effective performance of the proposed synchronization technique in the medical images encryption for telemedicine application.MINECO/ FEDER under the RTI2018-098913-B100 CV20-45250 and A-TIC- 080-UGR18 project

Control Architectures for Robotic Assistance in Beating Heart Surgery

Tese de doutoramento em Engenharia Electrotécnica e de Computadores, no ramo de especialização em Automação e Robótica, apresentada ao Departamento de Engenharia Electrotécnica e de Computadores da Faculdade de Ciências e Tecnologia da Universidade de CoimbraDoenças cardiovasculares são a primeira causa de morte no mundo. Todos os anos mais de 17 milhões de pessoas morrem, representando 29% do número total de mortes. As doenças coronárias são as mais críticas, atingindo mais de 7.2 milhões de mortes. Para reduzir o risco de morte, o "bypass" coronário é a intervenção cirúrgica mais comum. Atualmente este procedimento envolve uma esternotomia mediana e um "bypass" cardiopulmonar, permitindo que uma máquina externa implemente as funções de oxigenação e bombeamento de sangue. Contudo, esta máquina externa é fonte de muitas complicações pós-operatórias, incluindo a morte de pacientes. Estes problemas motivam o estudo e desenvolvimento de técnicas cirúrgicas sem parar o funcionamento do coração. Nestes casos, os batimentos cardíacos e a respiração representam as principais fontes de perturbação. Foram desenvolvidos estabilizadores mecânicos para diminuir localmente o movimento cardíaco. Colocado numa região de específica (por exemplo, na artéria coronária), estes estabilizadores limitam o movimento por pressão e sucção. Apesar dos melhoramentos feitos ao longo dos anos, ainda existe um movimento residual considerável, e o cirurgião tem que os compensar manualmente. Torna-se então natural incluir dispositivos robóticos para ajudar na prática médica, melhorando a precisão, segurançae conforto de tarefas cirúrgicas. O sistema cirúrgico da Vinci é atualmente o sistema robótico mais avançado para a prática médica, com elevado desempenho em tarefas de destreza, precisão e segurança, apesar de não fornecer soluções de realimentação táctil, nem de compensação automática de movimentos fisiológicos. O trabalho desta tese é na área da robótica para cirurgias cardíacas com o coração a bater. Baseada na realimentação da força, esta tese explora novas arquiteturas de controlo com compensação automática dos movimentos cardíacos. São feitos testes experimentais em cenários muito realistas, sem utilizar seres vivos. Um robô denominado "Heartbox" equipado com um coração real reproduz movimentos cardíacos, enquanto que outro robô manipulador aplica forças cirúrgicas nesse coração com batimento artificial. As forças de interação fornecem realimentação de contacto ao cirurgião. O principal desafio científico deste trabalho é a ligação de técnicas de compensação autónoma de movimentos fisiológicos com controlo de força e realimentação haptica.Cardiovascular diseases are the first cause of mortality in the world. More than 17 million people die every year, representing 29% of all global deaths. Among these, coronary heart diseases are the most critical ones, reaching up to 7.2 million deaths. To reduce the risk of death the coronary artery bypass grafting (CABG) is the most common surgical intervention. Currently, the procedure involves a median sternotomy, an incision in the thorax allowing a direct access to the heart, and a cardiopulmonary bypass (CPB), where heart and lung functionalities are performed by an extracorporal machine. Unfortunately the heart-lung machine is the greatest source of complications and post-operatory mortality for patients. Problems involved have motivated beating heart surgery that circumvent CPB procedure. Heartbeats and respiration represent the two main sources of disturbances during off-pump surgery. Mechanical stabilizers have been conceived for locally decreasing heart motion. Placed around a region of interest (e.g., coronary artery), these stabilizers constraint the motion by suction or pressure. Despite many improvements done over the years, considerable residual motion still remains and the surgeon have to manually compensate them. Robotic assistance has the potential to offer significant improvements to the medical practice in terms of precision, safety and comfort. Theda Vinci surgical system is the most popular and sophisticated. Although it has considerably improved dexterity, precision and safety, no solution for restoring tactile feedback to the surgeon exists and physiological motion compensation still needs to be manually canceled by the surgeon. The work presented in this thesis focus on robotic assistance for beating heart surgery. Based on force feedback, we designed new control architectures providing autonomous physiological motion compensation. Experimental assessments have been performed through a realistic scenario. A Heartbox robot equipped with an \textit{ex vivo} heart reproduces heart motion and a robot arm generates desired surgical forces on the moving heart. Interaction forces provide the haptic feedback for the surgeon. Merging autonomous motion compensation techniques with force control and haptic feedback is a major scientific challenge that we tackle in this work.FCT - SFRH/BD/74278/201

Magnetic Resonance Imaging of the Neonatal Cardiovascular System : Impact of Patent Ductus Arteriosus

The incidence of premature birth is increasing in absolute number and as a proportion of all births around the world. Many pathologies seen in this cohort are related to abnormal blood supply. Fetal and premature cardiovascular systems differ greatly as to maintain adequate blood flow to the developing organs in the uterine and extra-uterine environments require very different circulations. Subsequently following preterm birth the immature cardiovascular system undergoes abrupt adaptations, often resulting in the prolonged patency of the fetal shunt, ductus arteriosus. The impact of a patent ductus arteriosus (PDA) is poorly understood. However it is thought that large ductal shunt volumes may result in congestive cardiac failure and systemic hypo-­‐perfusion. Cardiac MRI has contributed greatly to the understanding of many cardiovascular diseases and congenital defects in paediatric and adult patients. Translating these imaging techniques to assess the preterm cardiovascular system requires careful optimization due to their condition, size and significantly increased heart rate. The work presented in this thesis employs multiple functional CMR techniques to investigate the preterm cardiovascular system in the presence and absence of PDA and the resultant cardiac function. A novel technique utilizing PC MRI to quantify PDA shunt volume and its impact on flow distribution is presented. Despite large shunt volumes, systemic circulation remained within normal range, although slight reduction is detectable when assessed at group level. Subsequently the impact of PDA and associated increased work load on left ventricular dimensions and function was then investigated using SSFP imaging. Results indicated that cardiac function was maintained even in the presence of large shunt volumes. Finally 4D PC sequences were employed to evaluate pulse wave velocity and flow regime within the preterm aorta, demonstrating the feasibility of hemodynamic assessment in this cohort. The findings of these studies provide insight into the impact of PDA. The reliable measurement and assessment of preterm cardiovascular system provides the potential to improve the understanding of the development and effects of certain pathologies seen in this cohort.Open Acces

Video Kinematic Evaluation: new insights on the cardiac mechanical function

The cardiac mechanical function plays a critical role in governing and regulating its performance under both normal and pathological conditions. The left ventricle has historically received more attention in both congenital and acquired heart diseases and was considered as the mainstay of normal hemodynamics. However, over the past few decades, there has been increasing recognition of the pivotal role of the right ventricle in determining functional performance status and prognosis in multiple conditions. Nonetheless, the ventricles should not be considered separately as they share the septum, are encircled with common myocardial fibers and are surrounded by the pericardium. Thus, changes in the filling of one ventricle may alter the mechanical function of its counterpart. This ventricular interdependence remains even after the removal of the pericardium because of constrictive pericarditis or during open chest surgery. Interestingly, during open chest surgery, only the right ventricle mechanical activity is visually checked by the surgeon and cardiologist due to the absence of an intraoperative imaging technique able to evaluate its complex function. Noteworthy, most of the imaging techniques available to clinicians are established for the assessment of the left ventricle, with the ejection fraction being the most used parameter. However, this value is a measure of global systolic function which comes short in identifying regional myocardial impairment and the mechanical contraction. Therefore, new approaches are needed to deeply investigate the mechanics of both ventricles and correctly assess the cardiac mechanical performance. In this thesis, I studied the mechanical function of the left ventricle through different modalities of cardiac magnetic resonance and employed an innovative imaging technique for the assessment of the right ventricle mechanical function during open chest surgery

Intravascular Ultrasound

Intravascular ultrasound (IVUS) is a cardiovascular imaging technology using a specially designed catheter with a miniaturized ultrasound probe for the assessment of vascular anatomy with detailed visualization of arterial layers. Over the past two decades, this technology has developed into an indispensable tool for research and clinical practice in cardiovascular medicine, offering the opportunity to gather diagnostic information about the process of atherosclerosis in vivo, and to directly observe the effects of various interventions on the plaque and arterial wall. This book aims to give a comprehensive overview of this rapidly evolving technique from basic principles and instrumentation to research and clinical applications with future perspectives

Advances in Electrocardiograms

Electrocardiograms have become one of the most important, and widely used medical tools for diagnosing diseases such as cardiac arrhythmias, conduction disorders, electrolyte imbalances, hypertension, coronary artery disease and myocardial infarction. This book reviews recent advancements in electrocardiography. The four sections of this volume, Cardiac Arrhythmias, Myocardial Infarction, Autonomic Dysregulation and Cardiotoxicology, provide comprehensive reviews of advancements in the clinical applications of electrocardiograms. This book is replete with diagrams, recordings, flow diagrams and algorithms which demonstrate the possible future direction for applying electrocardiography to evaluating the development and progression of cardiac diseases. The chapters in this book describe a number of unique features of electrocardiograms in adult and pediatric patient populations with predilections for cardiac arrhythmias and other electrical abnormalities associated with hypertension, coronary artery disease, myocardial infarction, sleep apnea syndromes, pericarditides, cardiomyopathies and cardiotoxicities, as well as innovative interpretations of electrocardiograms during exercise testing and electrical pacing

Aerospace Medicine and Biology: A Cumulative Index to the 1985 Issues

This publication is a cumulative index to the abstracts contained in the Supplements 268 through 279 of Aerospace Medicine and Biology: A Continuing Bibliography. It includes seven indexes - subject, personal author, corporate source, foreign technology, contract number, report number, and accession number

Cardiac Arrhythmias

Cardiac arrhythmias are common triggers of emergency admission to cardiology or high-dependency departments. Most cases are easy to diagnose and treat, while others may present a challenge to healthcare professionals. A translational approach to arrhythmias links molecular and cellular scientific research with clinical diagnostics and therapeutic methods, which may include both pharmacological and non-pharmacologic treatments. This book presents a comprehensive overview of specific cardiac arrhythmias and discusses translational approaches to their diagnosis and treatment

Characterization of flow dynamics in vessels with complex geometry using Doppler optical coherence tomography

The study of flow dynamics in complex geometry vessels is highly important in many biomedical applications where the knowledge of the mechanic interactions between the moving fluid and the housing media plays a key role for the determination of the parameters of interest, including the effect of blood flow on the possible rupture of atherosclerotic plaques. Doppler Optical Coherence Tomography (DOCT) is an optic, non-contact, non-invasive technique able to achieve detailed analysis of the flow/vessel interactions, allowing simultaneously high resolution imaging of the morphology and composition of the vessel and of the flow velocity distribution along the measured cross-section. DOCT system was developed to image high-resolution one-dimensional and multi-dimensional velocity distribution profiles of Newtonian and non-Newtonian fluids flowing in vessels with complex geometry, including Y-shaped and T-shaped vessels, vessels with aneurism, bifurcated vessels with deployed stent and scaffolds. The phantoms were built to study the interaction of the flow dynamics with different channel geometries and to map the related velocity profiles at several inlet volume flow rates. Feasibility studies for quantitative observation of the turbulence of flows arising within the complex geometry vessels are discussed. In addition, optical clearing of skin tissues has been utilized to achieve DOCT imaging of human blood vessels in vivo, at a depth up to 1.7 mm. Two-dimensional OCT images of complex flow velocity profiles in blood vessel phantom and in vivo subcutaneous human skin tissues are presented. The effect of optical clearing on in vivo images is demonstrated and discussed. DOCT was also applied for imaging scaffold structures and for mapping flow distributions within the scaffold.EThOS - Electronic Theses Online ServiceGBUnited Kingdo