34 research outputs found
Towards Patient Specific Mitral Valve Modelling via Dynamic 3D Transesophageal Echocardiography
Mitral valve disease is a common pathologic problem occurring increasingly in an aging population, and many patients suffering from mitral valve disease require surgical intervention. Planning an interventional approach from diagnostic imaging alone remains a significant clinical challenge. Transesophageal echocardiography (TEE) is the primary imaging modality used diagnostically, it has limitations in image quality and field-of-view. Recently, developments have been made towards modelling patient-specific deformable mitral valves from TEE imaging, however, a major barrier to producing accurate valve models is the need to derive the leaflet geometry through segmentation of diagnostic TEE imaging. This work explores the development of volume compounding and automated image analysis to more accurately and quickly capture the relevant valve geometry needed to produce patient-specific mitral valve models.
Volume compounding enables multiple ultrasound acquisitions from different orientations and locations to be aligned and blended to form a single volume with improved resolution and field-of-view. A series of overlapping transgastric views are acquired that are then registered together with the standard en-face image and are combined using a blending function. The resulting compounded ultrasound volumes allow the visualization of a wider range of anatomical features within the left heart, enhancing the capabilities of a standard TEE probe.
In this thesis, I first describe a semi-automatic segmentation algorithm based on active contours designed to produce segmentations from end-diastole suitable for deriving 3D printable molds. Subsequently I describe the development of DeepMitral, a fully automatic segmentation pipeline which leverages deep learning to produce very accurate segmentations with a runtime of less than ten seconds. DeepMitral is the first reported method using convolutional neural networks (CNNs) on 3D TEE for mitral valve segmentations. The results demonstrate very accurate leaflet segmentations, and a reduction in the time and complexity to produce a patient-specific mitral valve replica. Finally, a real-time annulus tracking system using CNNs to predict the annulus coordinates in the spatial frequency domain was developed. This method facilitates the use of mitral annulus tracking in real-time guidance systems, and further simplifies mitral valve modelling through the automatic detection of the annulus, which is a key structure for valve quantification, and reproducing accurate leaflet dynamics
The link between true larvae and parasitic forms within Isopoda – insights from the fossil record
Isopoda is a species-rich ingroup of Eucrustacea (crustaceans and insects), whose representatives live in a variety of habitats from the deep sea to arid terrestrial landscapes. Isopoda is very diverse regarding the life styles which are present in its species. There are herbivorous and detritivorous species as well as predators and scavengers. Parasitism, as an interaction between animals where one animal exploits resources from the other to it’s disadvantage, is far from being a fringe phenomenon inside Isopoda – a large proportion of species in Isopoda are either parasites or micro-predators (also referred to as temporary parasites). Parasitic forms (in the wider sense, including micro-predators) of Isopoda can be found in a few ingroups, which are generally thought to be closely related or to form a monophyletic group. Among the parasitic forms there are many species whose development includes a strong ecological and morphological differentiation between the immatures and the adults (larval development). Despite the ecological importance in modern ecosystems, the fossil record of parasitic forms of Isopoda is rather sparse.
The aim of this study was to recognise and thoroughly document potentially parasitic forms of Isopoda in the fossil record, using modern imaging techniques. By interpreting the systematic positions of the extinct species, the fossil forms could be compared with closely related extant forms for which there are observations of their behaviour in their natural environment. The goal was also to recognise potentially immature forms, which could provide insights into the evolution of developmental patterns within Isopoda, especially with respect to the parasitic forms in which there seems to be a stronger tendency for differentiation between adults and their offspring. Fossils have the potential to yield combinations of characters that are not present in extant species and are thereby important to reconstruct the evolution of characters. Fossils of such value were explicitly searched for. Furthermore, the fossils inspected in the studies of this dissertation should be used to provide a temporal context to the evolution of parasitism and larval development within Isopoda.
Two well-preserved fossils of presumably non-parasitic forms within the group Cymothoida (in which there are also parasitic forms) from fossilised mid-Cretaceous resin were studied (study I). One of them was interpreted as an immature, which resembles the other, larger, specimen, which is assumed to be of a later developmental stage, in most aspects of the body morphology – except for the absence of a well developed leg on the posterior-most walking leg, which absence in immatures is an apomorphy of the group Mancoidea, which comprises Isopoda. This represents, together with a recently published fossil of the same site, the oldest record of an immature specimen in Isopoda.
Multiple minute fossils of the group Epicaridea (parasites of crustaceans) from two different mid- and Late Cretaceous amber localities (studies I and III) were studied. They represent the oldest body fossils of the group Epicaridea, which has a rich record of fossil traces which its representatives left on their host (growth responses by the host) while feeding on them. Based on the available morphological features, the fossils were identified as either larvae (of the cryptoniscium stage) or paedomorphic adult males. Their presence in the fossil record suggests that the complex life cycle that is found in extant species of Epicaridea was already present in the Cretaceous.
An assemblage of multiple strongly compressed fossils from the Eocene of the Czech Republic was documented (study IV). The specimens were identified as being either close relatives to or representatives of group Cymothoidae (mostly parasites of fishes in the extant fauna). This marks the first and therefore oldest reliable record of this lineage in the fossil record. The assemblage contains specimens of different body sizes. Together with differences in the overall body shape this indicates the presence of immature stages.
Fossils of Urda, an extinct, potentially non-monophyletic group with a unique combination of characters, were analysed (study V). The fossils are interpreted as the closest so far known relatives of the extant group Gnathiidae (temporary parasites of fishes), with which representatives they share a number of apomorphic characters; a convincing apomorphy for Urda could not be found. The fossils, for which there is no indication that they represent remains of immatures, are very similar in many aspects to immature forms of Gnathiidae, in contrast to which they, however, lack the paedomorphic absence of legs on one segment of the trunk. The occurrence of some fossils of Urda on fossils of fishes suggests a syn-vivo interaction, such as parasitism or commensalism. Fossils of Urda provide important information about the character evolution towards modern, fish-parasites of the group Gnathiidae.
The evolution of larvae within Isopoda seems to be deeply interlinked with the evolution of parasitism. The fossil record yields specimens with a larval development that date back to the mid-Cretaceous. These specimens simultaneously represent the oldest fossils which can be identified as belonging to extant groups in which all species have a parasitic life style. Close relatives of extant parasites date back even further, to the Lower Jurassic. Overall, despite still being patchy, the fossil record of Isopoda provides unique insights into the evolution of parasitic forms as well as into the differentiation between adults and immature forms
Mastering Endo-Laparoscopic and Thoracoscopic Surgery
This is an open access book. The book focuses mainly on the surgical technique, OR setup, equipments and devices necessary in minimally invasive surgery (MIS). It serves as a compendium of endolaparoscopic surgical procedures. It is an official publication of the Endoscopic and Laparoscopic Surgeons of Asia (ELSA). The book includes various sections covering basic skills set, devices, equipments, OR setup, procedures by area. Each chapter cover introduction, indications and contraindications, pre-operative patient’s assessment and preparation, OT setup (instrumentation required, patient’s position, etc.), step by step description of surgical procedures, management of complications, post-operative care. It includes original illustrations for better understanding and visualization of specific procedures. The book serves as a practical guide for surgical residents, surgical trainees, surgical fellows, junior surgeons, surgical consultants and anyone interested in MIS. It covers most of the basic and advanced laparoscopic and thoracoscopic surgery procedures meeting the curriculum and examination requirements of the residents
Recent Advances in Wound Healing
The human wound-healing process could be divided into four discrete phases, which have also been indicated as the hemostasis, the inflammatory, the proliferation, and the remodeling phase. For a wound to be healed efficaciously, all four phases must sequentially happen at an expected time setting. Numerous aspects can hinder one or more stages of this procedure, thus can cause inappropriate or diminished wound healing. This book reviews the recent literature on the most significant factors that affect wound healing and the potential cellular and/or molecular mechanisms involved. The factors discussed include physiology of wound healing, interferon, stem cells and photobiomodulation, chronic venous ulcer, chronic fistula, bionanomaterials, topical antiseptic agents, including silver and sodium hypochlorite solution, diabetic ulcers, and nutritional supplements such as copper
Advanced Applications of Rapid Prototyping Technology in Modern Engineering
Rapid prototyping (RP) technology has been widely known and appreciated due to its flexible and customized manufacturing capabilities. The widely studied RP techniques include stereolithography apparatus (SLA), selective laser sintering (SLS), three-dimensional printing (3DP), fused deposition modeling (FDM), 3D plotting, solid ground curing (SGC), multiphase jet solidification (MJS), laminated object manufacturing (LOM). Different techniques are associated with different materials and/or processing principles and thus are devoted to specific applications. RP technology has no longer been only for prototype building rather has been extended for real industrial manufacturing solutions. Today, the RP technology has contributed to almost all engineering areas that include mechanical, materials, industrial, aerospace, electrical and most recently biomedical engineering. This book aims to present the advanced development of RP technologies in various engineering areas as the solutions to the real world engineering problems
Preclinical evaluation of nanoparticle enhanced breast cancer diagnosis and radiation therapy
Triple negative breast cancer (TNBC) is an aggressive type of cancer which makes up 15-20% of all newly diagnosed cases, lacking the main target molecules for tumor specific treatment. Surgery or systemic therapy by chemotherapy are frequently used in the clinic and combined with radiation therapy to improve locoregional control in breast cancer patients after surgery. With a poor prognosis, there is a clear need to explore new treatment options for TNBC. The aim of the here presented PhD project was to evaluate the feasibility to enhance the biological effect of radiation therapy and increase tumor contrast for diagnosis by applying an in vivo microCT imaging system in combination with barium nanoparticles (BaNPs) in a pH8N8 WAP-T-NP8 mouse model for TNBC. Characterization of the BaNPs revealed strong x-ray attenuation and no toxic effects in different cancer and normal cell lines. Furthermore, irradiation of cancer cells using low energy x-rays in the keV range by a microCT resulted in a significant reduction on colony formation capability. In vitro, this low energy irradiation effect on clonogenic tumor cell survival was enhanced in the presence of BaNPs. Next, a subcutaneous lung cancer mouse model in immunodeficient mice and an orthotopic syngeneic mouse model for breast cancer was applied for further in vivo evaluation. Once the treatment plan was optimized regarding the applied x-ray doses and the frequency of irradiation, low energy radiation therapy within a classical in vivo microCT significantly reduced tumor growth or even resulted in shrinkage of the tumors without visible side effects and weight loss in comparison to untreated controls. However, the intratumoral application of BaNPs was not able to increase the irradiation effect on tumor growth kinetics. This might be in part due to inhomogeneous distribution of BaNPs within the tumor observed by microCT imaging. K-edge subtraction imaging as well as x-ray fluorescence of explanted tumor samples confirmed these findings. To localize the BaNPs in 3D to specific sites within the tumor environment and to detect morphological alterations within the tumor due to irradiation in proximity to BaNPs an ex-vivo imaging based analytic platform was established, utilizing co-registration of microCT and histology data. This imaging approach co-localized BaNPs with CD68 positive phagocytic cells and revealed a non-uniform distribution of the BaNPs within the tumor, however with no signs of locally enhanced radiation effects. Furthermore, antibody functionalized BaNPs were generated for systemic application. Analysis of biodistribution revealed that EpCAM labeled BaNPs did not reach the tumor after intra-venous administration, but accumulated in liver and spleen, demonstrated by a strong CT contrast within these organs.
In summary, I showed that low energy radiation therapy by applying an in vivo microCT significantly reduced tumor volumes in comparison to untreated tumors in a syngeneic breast cancer tumor mouse model resembling TNBC. However, BaNPs while enhancing the effectiveness of irradiation on tumor cells in vitro, did not improve the irradiation effect on tumor growth in vivo.2021-07-1
Microbial Biofilms
In the book Microbial Biofilms: Importance and applications, eminent scientists provide an up-to-date review of the present and future trends on biofilm-related research. This book is divided with four subdivisions as biofilm fundamentals, applications, health aspects, and their control. Moreover, this book also provides a comprehensive account on microbial interactions in biofilms, pyocyanin, and extracellular DNA in facilitating Pseudomonas aeruginosa biofilm formation, atomic force microscopic studies of biofilms, and biofilms in beverage industry. The book comprises a total of 21 chapters from valued contributions from world leading experts in Australia, Bulgaria, Canada, China, Serbia, Germany, Italy, Japan, the United Kingdom, the Kingdom of Saudi Arabia, Republic of Korea, Mexico, Poland, Portugal, and Turkey. This book may be used as a text or reference for everyone interested in biofilms and their applications. It is also highly recommended for environmental microbiologists, soil scientists, medical microbiologists, bioremediation experts, and microbiologists working in biocorrosion, biofouling, biodegradation, water microbiology, quorum sensing, and many other related areas. Scientists in academia, research laboratories, and industry will also find it of interest
Molecular Imaging
The present book gives an exceptional overview of molecular imaging. Practical approach represents the red thread through the whole book, covering at the same time detailed background information that goes very deep into molecular as well as cellular level. Ideas how molecular imaging will develop in the near future present a special delicacy. This should be of special interest as the contributors are members of leading research groups from all over the world
Augmented Reality and Artificial Intelligence in Image-Guided and Robot-Assisted Interventions
In minimally invasive orthopedic procedures, the surgeon places wires, screws, and surgical implants through the muscles and bony structures under image guidance. These interventions require alignment of the pre- and intra-operative patient data, the intra-operative scanner, surgical instruments, and the patient. Suboptimal interaction with patient data and challenges in mastering 3D anatomy based on ill-posed 2D interventional images are essential concerns in image-guided therapies.
State of the art approaches often support the surgeon by using external navigation systems or ill-conditioned image-based registration methods that both have certain drawbacks. Augmented reality (AR) has been introduced in the operating rooms in the last decade; however, in image-guided interventions, it has often only been considered as a visualization device improving traditional workflows. Consequently, the technology is gaining minimum maturity that it requires to redefine new procedures, user interfaces, and interactions.
This dissertation investigates the applications of AR, artificial intelligence, and robotics in interventional medicine. Our solutions were applied in a broad spectrum of problems for various tasks, namely improving imaging and acquisition, image computing and analytics for registration and image understanding, and enhancing the interventional visualization. The benefits of these approaches were also discovered in robot-assisted interventions.
We revealed how exemplary workflows are redefined via AR by taking full advantage of head-mounted displays when entirely co-registered with the imaging systems and the environment at all times. The proposed AR landscape is enabled by co-localizing the users and the imaging devices via the operating room environment and exploiting all involved frustums to move spatial information between different bodies. The system's awareness of the geometric and physical characteristics of X-ray imaging allows the exploration of different human-machine interfaces. We also leveraged the principles governing image formation and combined it with deep learning and RGBD sensing to fuse images and reconstruct interventional data.
We hope that our holistic approaches towards improving the interface of surgery and enhancing the usability of interventional imaging, not only augments the surgeon's capabilities but also augments the surgical team's experience in carrying out an effective intervention with reduced complications
A Review on Advances in Intra-operative Imaging for Surgery and Therapy: Imagining the Operating Room of the Future
none4openZaffino, Paolo; Moccia, Sara; De Momi, Elena; Spadea, Maria FrancescaZaffino, Paolo; Moccia, Sara; De Momi, Elena; Spadea, Maria Francesc