23 research outputs found

    Guiding Vascular Access with the Sonic Flashlight - Preclinical Development and Validation

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    This dissertation concerns the development of a device called the Sonic Flashlight, which employs a novel method for viewing real-time ultrasound images inside the body exactly at the location where it is being scanned. While other augmented reality methods have previously been developed to view ultrasound and other medical imaging modalities within the body, they are generally much more complicated, slower and less robust than the Sonic Flashlight.In this dissertation, we aim to develop the Sonic Flashlight towards one particular clinical application, central vascular access, and lay the groundwork leading to the first clinical trials. The goal of central vascular access is to insert a catheter into a major vein to deliver medications in large quantities. These veins are usually not visible to the naked eye, so real-time ultrasound is employed to guide the needle into them. While real-time ultrasound guidance significantly enhances the safety of central venous access, learning this skill can be a challenge for the novice user, one major obstacle being the displaced sense of hand-eye coordination that occurs when the operator must look away from the operating field to view the conventional ultrasound monitor.We developed the 5th generation Sonic Flashlight, as well as a novel calibration method, called thin-gel calibration, as part of this dissertation. The thin-gel system allows us to accurately calibrate the Sonic Flashlight and measure the calibration accuracy. Finally, experiments were conducted with a variety of subject populations using vascular ultrasound phantoms and cadavers to validate Sonic Flashlight guidance, demonstrating that the device is ready for clinical trials

    Development and evaluation of a novel method for in-situ medical image display

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    Three-dimensional (3D) medical imaging, including computed tomography (CT) and magnetic resonance (MR), and other modalities, has become a standard of care for diagnosis of disease and guidance of interventional procedures. As the technology to acquire larger, more magnificent, and more informative medical images advances, so too must the technology to display, interact with, and interpret these data.This dissertation concerns the development and evaluation of a novel method for interaction with 3D medical images called "grab-a-slice," which is a movable, tracked stereo display. It is the latest in a series of displays developed in our laboratory that we describe as in-situ, meaning that the displayed image is embedded in a physical 3D coordinate system. As the display is moved through space, a continuously updated tomographic slice of a 3D medical image is shown on the screen, corresponding to the position and orientation of the display. The act of manipulating the display through a "virtual patient" preserves the perception of 3D anatomic relationships in a way that is not possible with conventional, fixed displays. The further addition of stereo display capabilities permits augmentation of the tomographic image data with out-of-plane structures using 3D graphical methods.In this dissertation we describe the research and clinical motivations for such a device. We describe the technical development of grab-a-slice as well as psychophysical experiments to evaluate the hypothesized perceptual and cognitive benefits. We speculate on the advantages and limitations of the grab-a-slice display and propose future directions for its use in psychophysical research, clinical settings, and image analysis

    Augmented Reality Ultrasound Guidance in Anesthesiology

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    Real-time ultrasound has become a mainstay in many image-guided interventions and increasingly popular in several percutaneous procedures in anesthesiology. One of the main constraints of ultrasound-guided needle interventions is identifying and distinguishing the needle tip from needle shaft in the image. Augmented reality (AR) environments have been employed to address challenges surrounding surgical tool visualization, navigation, and positioning in many image-guided interventions. The motivation behind this work was to explore the feasibility and utility of such visualization techniques in anesthesiology to address some of the specific limitations of ultrasound-guided needle interventions. This thesis brings together the goals, guidelines, and best development practices of functional AR ultrasound image guidance (AR-UIG) systems, examines the general structure of such systems suitable for applications in anesthesiology, and provides a series of recommendations for their development. The main components of such systems, including ultrasound calibration and system interface design, as well as applications of AR-UIG systems for quantitative skill assessment, were also examined in this thesis. The effects of ultrasound image reconstruction techniques, as well as phantom material and geometry on ultrasound calibration, were investigated. Ultrasound calibration error was reduced by 10% with synthetic transmit aperture imaging compared with B-mode ultrasound. Phantom properties were shown to have a significant effect on calibration error, which is a variable based on ultrasound beamforming techniques. This finding has the potential to alter how calibration phantoms are designed cognizant of the ultrasound imaging technique. Performance of an AR-UIG guidance system tailored to central line insertions was evaluated in novice and expert user studies. While the system outperformed ultrasound-only guidance with novice users, it did not significantly affect the performance of experienced operators. Although the extensive experience of the users with ultrasound may have affected the results, certain aspects of the AR-UIG system contributed to the lackluster outcomes, which were analyzed via a thorough critique of the design decisions. The application of an AR-UIG system in quantitative skill assessment was investigated, and the first quantitative analysis of needle tip localization error in ultrasound in a simulated central line procedure, performed by experienced operators, is presented. Most participants did not closely follow the needle tip in ultrasound, resulting in 42% unsuccessful needle placements and a 33% complication rate. Compared to successful trials, unsuccessful procedures featured a significantly greater (p=0.04) needle-tip to image-plane distance. Professional experience with ultrasound does not necessarily lead to expert level performance. Along with deliberate practice, quantitative skill assessment may reinforce clinical best practices in ultrasound-guided needle insertions. Based on the development guidelines, an AR-UIG system was developed to address the challenges in ultrasound-guided epidural injections. For improved needle positioning, this system integrated A-mode ultrasound signal obtained from a transducer housed at the tip of the needle. Improved needle navigation was achieved via enhanced visualization of the needle in an AR environment, in which B-mode and A-mode ultrasound data were incorporated. The technical feasibility of the AR-UIG system was evaluated in a preliminary user study. The results suggested that the AR-UIG system has the potential to outperform ultrasound-only guidance

    Recent advances in robot-assisted echography: Combining perception, control and cognition

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    Echography imaging is an important technique frequently used in medical diagnostics due to low-cost, non-ionising characteristics, and pragmatic convenience. Due to the shortage of skilful technicians and injuries of physicians sustained from diagnosing several patients, robot-assisted echography (RAE) system is gaining great attention in recent decades. A thorough study of the recent research advances in the field of perception, control and cognition techniques used in RAE systems is presented in this study. This survey introduces the representative system structure, applications and projects, and products. Challenges and key technological issues faced by the traditional RAE system and how the current artificial intelligence and cobots attempt to overcome these issues are summarised. Furthermore, significant future research directions in this field have been identified by this study as cognitive computing, operational skills transfer, and commercially feasible system design

    Ultrasound-Augmented Laparoscopy

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    Laparoscopic surgery is perhaps the most common minimally invasive procedure for many diseases in the abdomen. Since the laparoscopic camera provides only the surface view of the internal organs, in many procedures, surgeons use laparoscopic ultrasound (LUS) to visualize deep-seated surgical targets. Conventionally, the 2D LUS image is visualized in a display spatially separate from that displays the laparoscopic video. Therefore, reasoning about the geometry of hidden targets requires mentally solving the spatial alignment, and resolving the modality differences, which is cognitively very challenging. Moreover, the mental representation of hidden targets in space acquired through such cognitive medication may be error prone, and cause incorrect actions to be performed. To remedy this, advanced visualization strategies are required where the US information is visualized in the context of the laparoscopic video. To this end, efficient computational methods are required to accurately align the US image coordinate system with that centred in the camera, and to render the registered image information in the context of the camera such that surgeons perceive the geometry of hidden targets accurately. In this thesis, such a visualization pipeline is described. A novel method to register US images with a camera centric coordinate system is detailed with an experimental investigation into its accuracy bounds. An improved method to blend US information with the surface view is also presented with an experimental investigation into the accuracy of perception of the target locations in space

    Optical coherence tomography: evaluation and clinical application

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    The ability to examine the appearance of the retina is of paramount importance for the diagnosis and monitoring of ophthalmic disease and for the evaluation of treatment outcomes. Direct cross-sectional imaging of retinal structure could be useful for early diagnosis and more sensitive monitoring of a variety of retinal conditions such as macular oedema and glaucoma. The view of the fundus given by ophthalmoscopy provides very limited depth information and clinicians will often have to resort to additional techniques such as flourescein angiography or visual field testing for information on structural abnormalities within the retina. Other currently available imaging techniques do not provide sufficient depth resolution to produce useful cross-sectional images of retinal structure. Optical coherence tomography (OCT) is a new imaging technique which is capable of producing cross-sectional images of the retina with a resolution that surpasses that of conventional imaging techniques. This new technique has axial resolution of around 1 O.tm and can resolve individual retinal layers, thus providing information on retinal structure. In principle, OCT is very similar to ultrasound however it makes use of a light source rather than an acoustic one. The technique is non-contact and non-invasive and is generally well tolerated by patients. This thesis describes the evaluation of this new imaging technique with regards to its potential within routine clinical practice. A number of investigations were performed to fuffil this evaluation. Tests were carried out to experimentally measure the system's resolution and the accuracy and precision of measurements made from the OCT scans. A number of factors that could affect the quality of the scans were identified and their effects were minimised wherever possible. The software provided with the system was rigorously tested and potential sources of error were identified. Various studies were undertaken to quantify the repeatability and reproducibility of measurements made from scans and normative values were established. These results were used to assess the ability of the technique to detect and quantify several retinal disorders. The potential of the technique for corneal imaging was investigated - a scanning protocol was established and customised software for processing cornea! scans was developed. The relationship between OCT bands and retinal morphology was investigated by correlating scans from canine retina with corresponding light microscopy images and by observing the position of retinal abnormalities on scans from patients with a variety of conditions that affected different parts of the retina. Finally the clinical potential of OCT was investigated by carrying out various studies on a number of retinal conditions. Further clinical studies which combine anatomical information from OCT with functional information from electrophysiology are currently underway. Current developments are aimed at improving the imaging processing features and user interface so as to provide a more robust, user-friendly system for routine clinical use

    Nondestructive evaluation

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    Design, Fabrication, and Testing of a Sheathed Embolization Device

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    Endovascular embolization is an interventional procedure to seal off diseased vasculature from systemic circulation. Shape memory polymer (SMP) foams are a promising embolic material that can undergo shape change when exposed to stimuli, exhibit a positive healing response, and aid in rapid occlusion. SMP foams are porous materials that are composed of struts and membranes that pose a risk of generating particles during device fabrication or delivery. Herein, a sheathed embolization device (SED) was designed, fabricated, and tested to occlude a left atrial appendage (LAA) and to mitigate the generation of foam particles. The SED consists of a thin polyurethane membrane that fully encapsulates the SMP foam, and is able to undergo shape change from a compressed state to an expanded state. Material properties of the device were characterized with differential scanning calorimetry, scanning electron microscopy, and Fourier transform infrared spectroscopy. The SED was tested in terms of its ability to occlude a patient-derived LAA model, its deliverability, and its ability to reduce particles. Results from the studies demonstrate the SED’s ability to be delivered minimally invasively, reduce particles, and occlude mock vasculature. Upon actuation in body-temperature fluid the SED achieved a 10x diameter expansion, making it ideal for endovascular applications. These preliminary results support the potential to utilize SEDs to occlude vasculature while mitigating the risk of unintended ischemia due to device-based particles. The results also demonstrate the potential to integrate the SED with third- party devices or components to develop functional embolization devices, such as left atrial appendage closure devices

    Design, Fabrication, and Testing of a Sheathed Embolization Device

    Get PDF
    Endovascular embolization is an interventional procedure to seal off diseased vasculature from systemic circulation. Shape memory polymer (SMP) foams are a promising embolic material that can undergo shape change when exposed to stimuli, exhibit a positive healing response, and aid in rapid occlusion. SMP foams are porous materials that are composed of struts and membranes that pose a risk of generating particles during device fabrication or delivery. Herein, a sheathed embolization device (SED) was designed, fabricated, and tested to occlude a left atrial appendage (LAA) and to mitigate the generation of foam particles. The SED consists of a thin polyurethane membrane that fully encapsulates the SMP foam, and is able to undergo shape change from a compressed state to an expanded state. Material properties of the device were characterized with differential scanning calorimetry, scanning electron microscopy, and Fourier transform infrared spectroscopy. The SED was tested in terms of its ability to occlude a patient-derived LAA model, its deliverability, and its ability to reduce particles. Results from the studies demonstrate the SED’s ability to be delivered minimally invasively, reduce particles, and occlude mock vasculature. Upon actuation in body-temperature fluid the SED achieved a 10x diameter expansion, making it ideal for endovascular applications. These preliminary results support the potential to utilize SEDs to occlude vasculature while mitigating the risk of unintended ischemia due to device-based particles. The results also demonstrate the potential to integrate the SED with third- party devices or components to develop functional embolization devices, such as left atrial appendage closure devices

    Marshall Space Flight Center Research and Technology Report 2015

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    The investments in technology development we made in 2015 not only support the Agency's current missions, but they will also enable new missions. Some of these projects will allow us to develop an in-space architecture for human space exploration; Marshall employees are developing and testing cutting-edge propulsion solutions that will propel humans in-space and land them on Mars. Others are working on technologies that could support a deep space habitat, which will be critical to enable humans to live and work in deep space and on other worlds. Still others are maturing technologies that will help new scientific instruments study the outer edge of the universe-instruments that will provide valuable information as we seek to explore the outer planets and search for life
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