74 research outputs found
Augmented Reality
Augmented Reality (AR) is a natural development from virtual reality (VR), which was developed several decades earlier. AR complements VR in many ways. Due to the advantages of the user being able to see both the real and virtual objects simultaneously, AR is far more intuitive, but it's not completely detached from human factors and other restrictions. AR doesn't consume as much time and effort in the applications because it's not required to construct the entire virtual scene and the environment. In this book, several new and emerging application areas of AR are presented and divided into three sections. The first section contains applications in outdoor and mobile AR, such as construction, restoration, security and surveillance. The second section deals with AR in medical, biological, and human bodies. The third and final section contains a number of new and useful applications in daily living and learning
Multispectral image analysis in laparoscopy – A machine learning approach to live perfusion monitoring
Modern visceral surgery is often performed through small incisions. Compared to open surgery, these minimally invasive interventions result in smaller scars, fewer complications and a quicker recovery. While to the patients benefit, it has the drawback of limiting the physician’s perception largely to that of visual feedback through a camera mounted on a rod lens: the laparoscope. Conventional laparoscopes are limited by “imitating” the human eye. Multispectral cameras remove this arbitrary restriction of recording only red, green and blue colors. Instead, they capture many specific bands of light. Although these could help characterize important indications such as ischemia and early stage adenoma, the lack of powerful digital image processing prevents realizing the technique’s full potential.
The primary objective of this thesis was to pioneer fluent functional multispectral imaging (MSI) in laparoscopy. The main technical obstacles were: (1) The lack of image analysis concepts that provide both high accuracy and speed. (2) Multispectral image recording is slow, typically ranging from seconds to minutes. (3) Obtaining a quantitative ground truth for the measurements is hard or even impossible.
To overcome these hurdles and enable functional laparoscopy, for the first time in this field physical models are combined with powerful machine learning techniques. The physical model is employed to create highly accurate simulations, which in turn teach the algorithm to rapidly relate multispectral pixels to underlying functional changes. To reduce the domain shift introduced by learning from simulations, a novel transfer learning approach automatically adapts generic simulations to match almost arbitrary
recordings of visceral tissue. In combination with the only available video-rate capable multispectral sensor, the method pioneers fluent perfusion monitoring with MSI. This system was carefully tested in a multistage process, involving in silico quantitative evaluations, tissue phantoms and a porcine study. Clinical applicability was ensured through in-patient recordings in the context of partial nephrectomy; in these, the novel system characterized ischemia live during the intervention. Verified against a fluorescence reference, the results indicate that fluent, non-invasive ischemia detection and monitoring is now possible.
In conclusion, this thesis presents the first multispectral laparoscope capable of videorate functional analysis. The system was successfully evaluated in in-patient trials, and future work should be directed towards evaluation of the system in a larger study. Due to the broad applicability and the large potential clinical benefit of the presented functional estimation approach, I am confident the descendants of this system are an integral part
of the next generation OR
Rapid prototyping for biomedical engineering: current capabilities and Challenges
A new set of manufacturing technologies has emerged in the past decades to address market requirements in a customized way and to provide support for research tasks that require prototypes. These new techniques and technologies are usually referred to as rapid prototyping and manufacturing technologies, and they allow prototypes to be produced in a wide range of materials with remarkable precision in a couple of hours. Although they have been rapidly incorporated into product development methodologies, they are still under development, and their applications in bioengineering are continuously evolving. Rapid prototyping and manufacturing technologies can be of assistance in every stage of the development process of novel biodevices, to address various problems that can arise in the devices' interactions with biological systems and the fact that the design decisions must be tested carefully. This review focuses on the main fields of application for rapid prototyping in biomedical engineering and health sciences, as well as on the most remarkable challenges and research trends
Liver Biopsy
Liver biopsy is recommended as the gold standard method to determine diagnosis, fibrosis staging, prognosis and therapeutic indications in patients with chronic liver disease. However, liver biopsy is an invasive procedure with a risk of complications which can be serious. This book provides the management of the complications in liver biopsy. Additionally, this book provides also the references for the new technology of liver biopsy including the non-invasive elastography, imaging methods and blood panels which could be the alternatives to liver biopsy. The non-invasive methods, especially the elastography, which is the new procedure in hot topics, which were frequently reported in these years. In this book, the professionals of elastography show the mechanism, availability and how to use this technology in a clinical field of elastography. The comprehension of elastography could be a great help for better dealing and for understanding of liver biopsy
Objective assessment and feedback generation in dental surgical simulation : a framework based on correlating procedure and outcome
Fine motor skill is indispensable for a dentist. As in many other medical fields of study, the traditional surgical master-apprentice model is widely adopted in dental education. Recently, virtual reality (VR) simulators have been employed as supplementary components to the traditional skill-training curriculum, and numerous dental VR systems have been developed academically and commercially. However, the full promise of such systems has yet to be realized due to the lack of sufficient support for formative feedback. Without such a mechanism, evaluation still demands dedicated time of experts in scarce supply. With the aim to fill the gap of formative assessment using VR simulators in skill training in dentistry, this thesis presents a framework to objectively assess the surgical skill and generate formative feedback automatically. VR simulators enable collecting detailed data on relevant metrics throughout a procedure. Our approach to formative feedback is to correlate procedure metrics with the procedure outcome in order to identify the portions of a procedure that need to be improved. Prior to the correlation, the procedure outcome needs to be evaluated. The scoring algorithm designed in this thesis provides an overall score and identifies specific errors and their severity. Building upon this, we developed techniques to identify the portion of the procedure responsible for the errors. Specifically, for the errors in the outcome the responsible portions of the procedure are identified based on correlation of location of the error. For some types of feedback one mode may be more suitable than another. Tutoring formative feedback are provided using the video- and haptic- modalities. The effectiveness of the feedback systems have been evaluated with the dental students with randomized controlled trials and the findings show the feedback mechanisms to be effective and have potentials to use as valuable supplemental training resources
Haptische Mensch-Maschine-Schnittstelle für ein laparoskopisches Chirurgie-System
Für eine Vielzahl von Operationen im Bauchraum ist heute die Laparoskopie Stand der Technik, so z.B. die Cholezytektomie zur Entfernung der Gallenblase. Hierbei handelt es sich um ein minimalinvasives Verfahren bei dem der Zugang zum Operationsgebiet durch kleinste Schnitte in der Bauchdecke des Patienten erfolgt. Bei der Operation kommen lange starre Instrumente zu Einsatz. Im Gegensatz zu einer offenen Operation haben die Hände des Chirurgen keinen direkten Zugang zum operierten Gewebe. Ein Abtasten des Gewebes ist nicht möglich, der haptische Sinn zur Diagnose und Navigation im Operationsgebiet steht dem Operateur folglich nicht zur Verfügung. Diese Einschränkung erhöht die Komplexität laparoskopischer Eingriffe erheblich. Auch die Beweglichkeit im Operationsfeld ist stark eingeschränkt.
Eine technische Antwort auf diese Einschränkungen sind haptische Telemanipulationssysteme. Sie bestehen aus einer angetriebenen Instrumentenspitze sowie einem haptischen Bedienelement, das die Kontaktkräfte zwischen Instrumentenspitze und Gewebe an den Bediener meldet. Hierzu erfasst ein Kraftsensor an der Instrumentenspitze die auftretenden Kontaktkräfte. Antriebe im Bedienelement erzeugen daraus eine Kraftinformation und leiten sie über einen Mechanismus an den Bediener weiter.
Die vorliegende Arbeit befasst sich mit der Erweiterung der Entwurfsmethodik für haptische Bedienelemente und der Realisierung eines neuartigen Bedienelements. Basis ist eine Analyse des chirurgischen Szenarios in der minimalinvasiven Leberchirurgie. Daraus leitet sich das Entwurfsziel eines haptischen Bedienelementes mit drei kartesischen Freiheitsgraden ab.
Auf Grund ihrer guten dynamischen Eigenschaften sind besonders parallelkinematische Mechanismen zur Übertragung haptischer Informationen geeignet. Sie zeichnen sich durch eine große Struktursteifigkeit und geringe bewegte Massen aus. Ihr kinematisches Übertragungsverhalten ist hingegen meist komplex.
Aus der Analyse der kinematischen Bedingungen für ein rein kartesisches Ausgangsverhalten ergibt sich ein möglicher Lösungsraum geeigneter Topologien. Alle bestehen aus drei Beinen mit je 5 Gelenkfreiheitsgraden, einer Basis-Plattform und einer Tool-Centre-Point-Plattform zur Ausgabe der haptischen Information. Für den vorliegenden Fall ist eine RUU- bzw. DELTA-Struktur geeignet. Diese Struktur übersetzt drei Antriebsmomente in eine rein kartesische Ausgabe. Basierend auf der Analyse der kinematischen Entwurfsziele für haptische Mechanismen erfolgte eine Auslegung des Mechanismus im Hinblick auf isotropes, d.h. richtungsunabhängiges Übertragungsverhalten. Charakteristisches Maß ist die globale Konditionszahl.
Entscheidend für die Qualität der haptischen Rückmeldung ist das dynamische Übertragungsverhalten haptischer Bedienelemente. Für eindimensionale Systeme ist in der Literatur zur Modellierung der Zwei-Tor Ansatz basierend auf der elektromechanischen Netzwerktheorie eingeführt. Im Rahmen dieser Arbeit erfolgt erstmalig die Erweiterung auch für den mehrdimensionalen Fall. Damit ist es möglich, auch die dynamischen Eigenschaften mehrdimensionaler Mechanismen mit dem Zwei-Tor Ansatz abzubilden. Dies erlaubt Anwendung des Entwurfsverfahrens der "Transparenz" für mehrdimensionale Systeme.
Zur Analyse der mechanischen Eigenschaften des operierten Gewebes entstehen zwei Messplätze für die Frequenzbereiche f = 10...10^4 Hz (taktile Wahrnehmung) und f=DC...50 Hz (kinästhetische Wahrnehmung). Sie ermöglichen die messtechnische Charakterisierung der mechanischen Impedanz und die Ableitung mechanischer Schaltungen. Damit lässt sich die Impedanz des Gewebes rechnerisch im Gütekriterium der Transparenz zur Bewertung eines haptischen Telemanipulationssystems einsetzen.
Die Realisierung eines haptischen Bedienelements erfolgt für ein neuartiges, tragbares Teleoperationssystem. Das Bedienkonzept ist an Hand eines ergonomischen Funktionsmusters im Tierversuch evaluiert. Kernkomponente ist ein haptisches Joystick mit drei kartesischen Freiheitsgraden durch einen RUU-Mechanismus. Der Arbeitsraum beträgt 743,5 cm³. Das Bedienelement ist mit einer Impedanz-gesteuerten Systemstruktur entworfen und feinwerktechnisch umgesetzt. Als Antriebe kommen drei EC-Motoren zum Einsatz. Mit einem maximalen Moment von 0,2 Nm erzeugen sie eine haptische Rückmeldung von 5N in 82% des Volumens im Arbeitsraum. Die zum Betrieb erforderlichen kinematischen Berechnungen sind auf einem Steuerrechner implementiert. Zusammen mit der Leistungselektronik ist dieser in einem mobilen Rack integriert. Der Nachweis der Funktionsfähigkeit erfolgt an einem experimentellen Telemanipulationssystem im Laborbetrieb
Fluorescence Guided Surgery: Intra-Operative Fluorescent Imaging in Laparoscopic Colonic Tumour Resection and Laparoscopic Cholecystectomy Surgery
Introduction: Fluorescence-guided surgery could improve the operative decision-making process. Near Infrared Cholangiography (NIR-FC) with Indocyanine Green (ICG) in laparoscopic cholecystectomy (LC) may aid visualisation of bile duct anatomy. The c-met transmembrane protein is over-expressed in colorectal cancer (CRC). EMI-137 is a c-Met specific peptide coupled to fluorophore.
Methods: Twenty-two participants requiring LC were allocated to four dosing subgroups and received a single intravenous (I.V) dose of ICG before surgery. Biliary anatomy was assessed with NIR-FC and surgeon satisfaction was evaluated. c-Met transcription in HT-29 CRC cells was silenced with targeted SiRNA to demonstrate specificity of EMI-137. A HT-29 xenograft model was developed in female BALB/C mice. EMI-137 (0.18mg/kg) was injected into tail veins and biodistribution analysed by fluorescent imaging. c-Met immunopositivity was graded in matched normal and CRC tissue TMA samples obtained from the MRC CLASICC trial. Nine participants with colon cancer, received IV EMI-137 1-3 hours before laparoscopic tumour resection surgery. Tumour and lymph node (LN) fluorescence were assessed with a fluorescent laparoscope. Immunohistochemistry analysed c-Met expression.
Results: A prolonged ICG dosing interval consistently increased structure identification at LC and was preferred by the operating surgeon. c-Met was consistently overexpressed in CRC relative to normal tissue and could be visualised with EMI-137, comparable to indirect c-Met identification methods. EMI-137 uptake in tumour xenografts was observed for 6 hours post-administration.
At clinical trial, no serious adverse events related to EMI-137 were reported. Marked background fluorescence was observed in all participants; 4/9 showed mild increase in tumour fluorescence over background; 5/9 had histological LN metastases; no fluorescent LN were detected intraoperatively. All primary tumours (8/8) and malignant LN (15) exhibited moderate-high c-Met protein expression.
Conclusion: Prolonged ICG dosing improves visualisation of structures with NIR-FC at LC. EMI-137, binds specifically to the human c-Met protein, is safe but its intra-operative utility is limited by insufficient tumour-to-background ratios
Raman Spectroscopic Modeling Of T- Lymphocyte Activation And Detection Of Acute Renal Allograft Rejection
ABSTRACT
RAMAN SPECTROSCOPIC MODELING OF T-LYMPHOCYTE ACTIVATION AND DETECTION OF ACUTE RENAL ALLOGRAFT REJECTION
By
KRISTIAN L. BROWN
2010
Advisor: Gregory Auner, PhD
Major: Biomedical Engineering
Degree: Doctor of Philosophy
Despite the advances made in the area of kidney transplantation, the disparity between the demand and available donated organs remains a dominant and unresolved issue. Given the paucity of available renal allografts the preservation of existing grafts is vital. One factor that has negatively impacted renal allograft survival is acute rejection (AR). Traditionally, kidney transplant centers have used elevations in serum creatinine as a screening tool for detecting AR. However, with its diagnostic delay, low sensitivity, and low specificity, serum creatinine has proven to be an unreliable and problematic bio-marker. Acute rejection is an activated T lymphocyte driven process that leads to graft dysfunction and possible loss. The activation state of T lymphocytes is determined by the specific cell surface receptor composition present. A technologic tool that could resolve these receptor differences could detect T lymphocyte activation and thus provide a diagnostic modality for AR. Raman spectroscopy (RS), a laser-based technology that is able to characterize substances based on molecular vibrational signatures, represents this modality. Using T lymphocytes isolated from human peripheral blood and clean-catch urine we investigated three aspects of T lymphocyte activation using a modified RS system. First, we explored the sensitivity (the ability to detect activation) of a RS-based system by analyzing mixed lymphocyte reacted (MLR), Mitomycin C inactivated, and resting T lymphocytes at 785nm and 514.5nm wavelengths. Second, the specificity (the ability to distinguish T cells activated by different stimuli) of the system was determined by comparing the signatures of MLR and CD3/CD28-activated T lymphocytes. Third, we analyzed the biomolecular events that conveyed the spectral changes detected by RS. This was carried out by coupling RS analysis of Mitogen-activated T lymphocytes with antigen expression kinetic studies designed to quantify the intensity and timing of cell surface receptor up-regulation. We found that there were significant RS signature differences between the MLR and non-activated (inactivated and resting) T lymphocytes while there was only a trend toward difference seen between the resting and inactivated cellular populations. When analyzing MLR versus CD3/CD28-activated cells, both samples differed from the inactivated and resting groups and demonstrated differences in Raman shifts at multiple foci when compared to one another. Receptor expression kinetics of Mitogen-activated T lymphocytes analyzed at the early and late phases of activation showed differential antibody immuno-fluorescent intensity. This correlated to spectral differences at defined peaks. Moreover, when analyzing all forms of activation (i.e. MLR, CD3/CD28, or Mitogen) there were conserved and reproducible signature changes regardless of the mode of activation which supports the notion that there are receptor and receptor moiety changes that are required in all forms of T lymphocyte activation. This dissertation outlines the use of RS in the resolution and modeling of cell surface receptor differences that define T lymphocyte activation. The accurate detection of T lymphocyte activation within a biomatrix is the foundational step toward the development of a noninvasive tool capable of accurately detecting AR in real-time within the clinical setting
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