Advancements and Breakthroughs in Ultrasound Imaging

Ultrasonic imaging is a powerful diagnostic tool available to medical practitioners, engineers and researchers today. Due to the relative safety, and the non-invasive nature, ultrasonic imaging has become one of the most rapidly advancing technologies. These rapid advances are directly related to the parallel advancements in electronics, computing, and transducer technology together with sophisticated signal processing techniques. This book focuses on state of the art developments in ultrasonic imaging applications and underlying technologies presented by leading practitioners and researchers from many parts of the world

Surgical Subtask Automation for Intraluminal Procedures using Deep Reinforcement Learning

Intraluminal procedures have opened up a new sub-field of minimally invasive surgery that use flexible instruments to navigate through complex luminal structures of the body, resulting in reduced invasiveness and improved patient benefits. One of the major challenges in this field is the accurate and precise control of the instrument inside the human body. Robotics has emerged as a promising solution to this problem. However, to achieve successful robotic intraluminal interventions, the control of the instrument needs to be automated to a large extent. The thesis first examines the state-of-the-art in intraluminal surgical robotics and identifies the key challenges in this field, which include the need for safe and effective tool manipulation, and the ability to adapt to unexpected changes in the luminal environment. To address these challenges, the thesis proposes several levels of autonomy that enable the robotic system to perform individual subtasks autonomously, while still allowing the surgeon to retain overall control of the procedure. The approach facilitates the development of specialized algorithms such as Deep Reinforcement Learning (DRL) for subtasks like navigation and tissue manipulation to produce robust surgical gestures. Additionally, the thesis proposes a safety framework that provides formal guarantees to prevent risky actions. The presented approaches are evaluated through a series of experiments using simulation and robotic platforms. The experiments demonstrate that subtask automation can improve the accuracy and efficiency of tool positioning and tissue manipulation, while also reducing the cognitive load on the surgeon. The results of this research have the potential to improve the reliability and safety of intraluminal surgical interventions, ultimately leading to better outcomes for patients and surgeons

Characterisation and State Estimation of Magnetic Soft Continuum Robots

Minimally invasive surgery has become more popular as it leads to less bleeding, scarring, pain, and shorter recovery time. However, this has come with counter-intuitive devices and steep surgeon learning curves. Magnetically actuated Soft Continuum Robots (SCR) have the potential to replace these devices, providing high dexterity together with the ability to conform to complex environments and safe human interactions without the cognitive burden for the clinician. Despite considerable progress in the past decade in their development, several challenges still plague SCR hindering their full realisation. This thesis aims at improving magnetically actuated SCR by addressing some of these challenges, such as material characterisation and modelling, and sensing feedback and localisation. Material characterisation for SCR is essential for understanding their behaviour and designing effective modelling and simulation strategies. In this work, the material properties of commonly employed materials in magnetically actuated SCR, such as elastic modulus, hyper-elastic model parameters, and magnetic moment were determined. Additionally, the effect these parameters have on modelling and simulating these devices was investigated. Due to the nature of magnetic actuation, localisation is of utmost importance to ensure accurate control and delivery of functionality. As such, two localisation strategies for magnetically actuated SCR were developed, one capable of estimating the full 6 degrees of freedom (DOFs) pose without any prior pose information, and another capable of accurately tracking the full 6-DOFs in real-time with positional errors lower than 4~mm. These will contribute to the development of autonomous navigation and closed-loop control of magnetically actuated SCR

Control of Magnetic Continuum Robots for Endoscopy

The present thesis discusses the problem of magnetic actuation and control applied to millimetre-scale robots for endoluminal procedures. Magnetic actuation, given its remote manipulation capabilities, has the potential to overcome several limitations of current endoluminal procedures, such as the relatively large size, high sti�ness and limited dexterity of existing tools. The application of functional forces remotely facilitates the development of softer and more dexterous endoscopes, which can navigate with reduced discomfort for the patient. However, the solutions presented in literature are not always able to guarantee smooth navigation in complex and convoluted anatomical structures. This thesis aims at improving the navigational capabilities of magnetic endoluminal robots, towards achieving full autonomy. This is realized by introducing novel design, sensing and control approaches for magnetically actuated soft endoscopes and catheters. First, the application of accurate closed-loop control to a 1 Internal Permanent Magnet (IPM) endoscope was analysed. The proposed approach can guarantee better navigation capabilities, thanks to the manipulation of every mechanical Degree of Freedom (DOF) - 5 DOFs. Speci�cally, it was demonstrated that gravity can be balanced with su�cient accuracy to guarantee tip levitation. In this way contact is minimized and obstacle avoidance improved. Consequently, the overall navigation capabilities of the endoscope were enhanced for given application. To improve exploration of convoluted anatomical pathways, the design of magnetic endoscopes with multiple magnetic elements along their length was introduced. This approach to endoluminal device design can ideally allow manipulation along the full length; facilitating full shape manipulation, as compared to tip-only control. To facilitate the control of multiple magneto-mechanical DOFs along the catheters' length, a magnetic actuation method was developed based on the collaborative robotic manipulation of 2 External Permanent Magnets (EPMs). This method, compared to the state-of-the-art, facilitates large workspace and applied �eld, while guaranteeing dexterous actuation. Using this approach, it was demonstrated that it is possible to actuate up to 8 independent magnetic DOFs. In the present thesis, two di�erent applications are discussed and evaluated, namely: colonoscopy and navigational bronchoscopy. In the former, a single-IPM endoscopic approach is utilized. In this case, the anatomy is large enough to permit equipping the endoscope with a camera; allowing navigation by direct vision. Navigational bronchoscopy, on-the-other-hand, is performed in very narrow peripheral lumina, and navigation is informed via pre-operative imaging. The presented work demonstrates how the design of the magnetic catheters, informed by a pre-operative Computed Tomography (CT) scan, can mitigate the need for intra-operative imaging and, consequently, reduce radiation exposure for patients and healthcare workers. Speci�cally, an optimization routine to design the catheters is presented, with the aim of achieving follow-the-leader navigation without supervision. In both scenarios, analysis of how magnetic endoluminal devices can improve the current practice and revolutionize the future of medical diagnostics and treatment is presented and discussed

3D Visualization of Microvascular Networks Using Magnetic Particles: Application to Magnetic Resonance Navigation

RÉSUMÉ Les différentes modalités d'imagerie médicales fournissent des images cliniques de structures internes du corps humain à des fins diagnostiques et curatives. Leur première application en clinique remonte à trois décennies et depuis, grâce aux découvertes technologiques continues, de nouvelles fonctionnalités ont été intégrées aux systèmes d'imagerie. Aujourd'hui, des informations anatomiques et fonctionnelles précises peuvent être prélevées à partir de ces images dont la dimensionnalité a évolué du bidimensionnel au tridimensionnel incluant la dynamique. Une des modalités d'imagerie qui a largement profité de ces découvertes technologiques est l'imagerie par résonance magnétique (IRM). Par rapport aux autres techniques d'imagerie, l’IRM présente beaucoup d’avantages tels que la haute résolution spatiale et temporelle, le manque d'exposition aux rayonnements X et une pénétration tissulaire illimitée. Ceux-ci ont rendu l'IRM l'une des modalités les plus utilisées en clinique. Malgré des améliorations récentes dans le fonctionnement des bobines de réception d'IRM et aussi des algorithmes de reconstruction, des progrès supplémentaires sont requis afin d’améliorer la visualisation des microstructures en clinique. La visualisation des microvaisseaux avec un diamètre de 200 µm, reste au-delà des capacités des modalités d’imageries cliniques actuelles. Dans le traitement du cancer, une telle capacité pourrait fournir les informations nécessaires pour les nouvelles méthodes de délivrance ciblée de médicaments comme la navigation par résonance magnétique (NRM). Dans cette technique, afin d'améliorer l'indice thérapeutique, les microporteurs, chargés avec des agents thérapeutiques et des particules magnétiques, sont guidés le long d'une trajectoire qui mènerait vers une zone cancéreuse. Notre objectif est de telle trajectoire qui débuterait du bout du cathéter d'injection jusqu'à la destination finale, soit à proximité d’une zone tumorale. Le contraste de susceptibilité magnétique dans l'IRM fournit un moyen pour prononcer l'effet d'une particule magnétique même si sa taille est beaucoup plus petite que la résolution spatiale de l'IRM. En raison de leur susceptibilité magnétique élevée, les matériaux magnétiques provoquent une inhomogénéité dans le champ magnétique local de l'IRM dans une mesure beaucoup plus importante que leur taille réelle. L’inhomogénéité apparaît dans les images de gradient écho pondéré en T2* sous forme d'une perte de signal. Cette approche présente un moyen de visualisation de microstructures en exploitant leur artefact de susceptibilité.----------ABSTRACT Medical imaging modalities strive to provide clinical images of the human body’s internal structures for diagnosis and treatment purposes. Their first application in clinical trial services goes back to three decades and owing to continuous technological inventions, new capabilities have ever since been incorporated into the imaging systems. Today, anatomical and functional data with finer details and larger image sizes can be achieved and dimensionality of the images has been increased from 2D to dynamic 3D fields. One of the imaging modalities that have probably profited the most from technological findings is the magnetic resonance imaging (MRI). Compared to the other imaging techniques, MRI has various advantages such as high spatial and temporal resolution, lack of radiation exposure and unlimited tissue penetration. These have turned the MRI to one of the most available modalities clinically. Despite recent improvements in the MRI’s receiver coils and reconstruction algorithms, further progress is yet sought to improve the visualization of the microstructures using the clinical MR scanners. Visualization of microvessels with an inner overall cross-sectional area of approximately less than 200 µm, remains beyond capabilities of the current clinical imaging modalities. In cancer therapy, such capability would provide the information required for the new delivery methods such as magnetic resonance navigation (MRN). In the MRN, to enhance the therapeutic index, microcarriers loaded with therapeutic agents and magnetic particles are navigated along a planned trajectory in the vicinity of the treatment region. Our objective is to provide such a trajectory map within an area covering the location of the catheter tip for the injection site up to the extremity of the particles’ path i.e. vicinity of the treatment region such as a tumor site. Susceptibility-based negative contrast in the MRI provides a way to enlarge the effect of a magnetic particle whereas its actual size is much smaller than the MRI’s visualization capability. Due to their high magnetic susceptibility, magnetic materials cause an inhomogeneity in the local magnetic field of the MRI to an extent which is much larger than their actual size. The inhomogeneity appears in the T2*-weighed gradient echo images in the form of a signal void. This approach presents a method for visualization of microstructures through the susceptibility artifact

Imaging Sensors and Applications

In past decades, various sensor technologies have been used in all areas of our lives, thus improving our quality of life. In particular, imaging sensors have been widely applied in the development of various imaging approaches such as optical imaging, ultrasound imaging, X-ray imaging, and nuclear imaging, and contributed to achieve high sensitivity, miniaturization, and real-time imaging. These advanced image sensing technologies play an important role not only in the medical field but also in the industrial field. This Special Issue covers broad topics on imaging sensors and applications. The scope range of imaging sensors can be extended to novel imaging sensors and diverse imaging systems, including hardware and software advancements. Additionally, biomedical and nondestructive sensing applications are welcome