Photoelastic Stress Analysis Error Quantification in Vasculature Models for Robot Feedback Control

Abstract-Real-time and accurate stress calculation in walls of vasculature is desired to provide catheter insertion robots of feedback control without changing the catheter stiffness and lumen. This feedback source has also applications in endovascular surgery simulation for human skills and medical tools evaluation. For that purpose we consider photoelastic effect, as birefringence produced by light retardation relates with the stress inside the photoelastic materials. In this research a polariscope was designed for urethane elastomer vasculature models, the photoelastic coefficient of urethane elastomer was measured, and the camera system was calibrated to quantify and reduce error of the measurement system. An average error of 3.6% was found for the pressure range of 70-189 mmHg inside the model of urethane elastomer, this enables to calculate accurately stress in vasculature models during Human Blood Pressure Simulation (HBPS). That way we will be able to compare in a closed loop stress produced by HBPS and by the catheter motion when manipulated by a robot. I. INTRODUCTION RAINING with simulators reduces risks of injury and costs during practice for minimally invasive surgery C. Tercero is with Nagoya University, Aiichi-ken Nagoya-shi Chikusa-ku Furo-cho 1, 464-8603 JAPAN (phone: +81-52-788-6013; fax: +81-52-788-6013; e-mail: [email protected]). S. Ikeda is with Nagoya University, Aiichi-ken Nagoya-shi Chikusa-ku Furo-cho 1, 464-8603 JAPAN (phone: +81-52-788-6013; fax: +81-52-788-6013; e-mail: ikeda @robo.mein.nagoya-u.ac.jp). In previous studies photoelastic effect was used with a catheter insertion robot to evaluate catheters In this research we will present a calibration method for the transmittance equation to measure the optical path length, a polariscope designed for our simulation purpose, the deduction of the photoelastic coefficient of urethane elastomer, and the normalization parameters calibration to calculate the principal component of stress in the vasculature model with an inner pressure range of 40-189mmHg. It is desirable to measure stress with an error below 5% for the HBPS range, to use it as reference for control loop illustrated in figure 2. Photoelastic Stress Analysis Error Quantification i

Mechanical Flow Restoration in Acute Ischemic Stroke: A Model System of Cerebrovascular Occlusion: A Dissertation

Stroke is the third most common cause of death and a leading cause of disability in the United States. The existing treatments of acute ischemic stroke (AIS) involve pharmaceutical thrombolytic therapy and/or mechanical thrombectomy. The Food and Drug Administration (FDA)-approved recombinant tissue plasminogen activator (tPA) administration for treatment of stroke is efficacious, but has a short treatment time window and is associated with a risk of symptomatic hemorrhage. Other than tPA, the Mechanical Embolus Removal in Cerebral Ischemia (MERCI) retriever system and the Penumbra Aspiration system are both approved by the FDA for retrieval of thromboemboli in AIS patients. However, the previous clinical studies have shown that the recanalization rate of the MERCI system and the clinical outcome of the Penumbra system are not optimal. To identify the variables which could affect the performance of the thrombectomy devices, much effort has been devoted to evaluate thrombectomy devices in model systems, both in vivo and in vitro, of vascular occlusion. The goal of this study is to establish a physiologically realistic, in vitro model system for the preclinical assessment of mechanical thrombectomy devices. In this study, the model system of cerebrovascular occlusion was mainly composed of a human vascular replica, an embolus analogue (EA), and a simulated physiologic mock circulation system. The human vascular replica represents the geometry of the internal carotid artery (ICA)/middle cerebral artery (MCA) that is derived from image data in a population of patients. The features of the vasculature were characterized in terms of average curvature (AC), diameter, and length, and were used to determine the representative model. A batch manufacturing was developed to prepare the silicone replica. The EA is a much neglected component of model systems currently. To address this limitation, extensive mechanical characterization of commonly used EAs was performed. Importantly, the properties of the EAs were compared to specimens extracted from patients. In the preliminary tests of our model system, we selected a bovine EA with stiffness similar to the thrombi retrieved from the atherosclerotic plaques. This EA was used to create an occlusion in the aforesaid replica. The thrombectomy devices tested included the MERCI L5 Retriever, Penumbra system 054, Enterprise stent, and an ultrasound waveguide device. The primary efficacy endpoint was the amount of blood flow restored, and the primary safety endpoint was an analysis of clot fragments generated and their size distribution. A physiologically realistic model system of cerebrovascular occlusion was successfully built and applied for preclinical evaluation of thrombectomy devices. The recanalization rate of the thrombectomy device was related to the ability of the device to capture the EA during the removal of the device and the geometry of the cerebrovasculature. The risk of the embolic shower was influenced by the mechanical properties of the EA and the design of the thrombectomy device

An In-Shoe Laser Doppler Sensor for Assessing Plantar Blood Flow in the Diabetic Foot

An in-shoe laser Doppler sensor for assessing plantar blood flow in the diabetic foot. Jonathan Edwin Cobb Plantar ulceration is a complication of the diabetic foot prevalent in adults with type 11 diabetes mellitus. Although neuropathy, microvascular disease and biornechanical factors are all implicated, the mechanism by which the tissue becomes pre-disposed to damage remains unclear. Recent theories suggest that the nutritional supply to the tissue is compromised, either by increased flow through the arteriovenous anastomoses ('capillary steal' theory) or through changes in the micro vascu I ature (haemodynamic hypothesis). Clinical data to support these ideas has been limited to assessment of the unclad foot under rest conditions. A limitation of previous studies has been the exclusion of static and dynamic tissue loading, despite extensive evidence that these biornechanical factors are essential in the development of plantar ulceration. The present study has overcome these problems by allowing assessment of plantar blood flow, in-shoe, during standing and walking. The system comprises a laser Doppler blood flux sensor operating at 780nm, load sensor, measurement shoe, instrumentation, and analysis software. In-vitro calibration was performed using standard techniques. An in-vivo study of a small group of diabetic subjects indicated differences in the blood flux response between diabetic neuropaths, diabetics with vascular complications and a control group. For example, following a loading period of 120s, relative increases in response from rest to peak were: Control (150% to 259%), Vascular (-70% to 242%), Neuropathic (109%-174%) and recovery times to 50% of the peak response were: Control (33s to 45s), Vascular (43s to >120s), Neuropathic (>120s). Dynamic re-perfusion rates (arbitrary units per millisecond) obtained for the swing phase of gait were: Control (6.1 a. u/ms to 7.9 a. u/ms), Vascular (4 a. u/ms to 6.2 a. u/ms), Neuropathic (2.3 a. u/ms to 4.5 a. u/ms)

Book of Abstracts 15th International Symposium on Computer Methods in Biomechanics and Biomedical Engineering and 3rd Conference on Imaging and Visualization

In this edition, the two events will run together as a single conference, highlighting the strong connection with the Taylor & Francis journals: Computer Methods in Biomechanics and Biomedical Engineering (John Middleton and Christopher Jacobs, Eds.) and Computer Methods in Biomechanics and Biomedical Engineering: Imaging and Visualization (JoãoManuel R.S. Tavares, Ed.). The conference has become a major international meeting on computational biomechanics, imaging andvisualization. In this edition, the main program includes 212 presentations. In addition, sixteen renowned researchers will give plenary keynotes, addressing current challenges in computational biomechanics and biomedical imaging. In Lisbon, for the first time, a session dedicated to award the winner of the Best Paper in CMBBE Journal will take place. We believe that CMBBE2018 will have a strong impact on the development of computational biomechanics and biomedical imaging and visualization, identifying emerging areas of research and promoting the collaboration and networking between participants. This impact is evidenced through the well-known research groups, commercial companies and scientific organizations, who continue to support and sponsor the CMBBE meeting series. In fact, the conference is enriched with five workshops on specific scientific topics and commercial software.info:eu-repo/semantics/draf

Aerospace Medicine and Biology: A continuing bibliography with indexes (supplement 133)

This special bibliography lists 276 reports, articles, and other documents introduced into the NASA Scientific and Technical Information System in September 1974

Basis of bone metabolism around dental implants during osseointegration and periâ implant bone loss

Despite the growing number of publications in the field of implant dentistry, there are limited studies to date investigating the biology and metabolism of bone healing around dental implants and their implications in periâ implant marginal bone loss. The aim of this review article is to provide a thorough understanding of the biological events taking place during osseointegration and the subsequent early and late phases of bone remodeling around dental implants. An update on the coupling mechanism occurring during bone resorptionâ bone remodeling is provided, focused on the relevance of the osteocytes, bone lining cells and immune cells during bone maintenance. An electronic and manual literature search was conducted by three independent reviewers in several databases, including MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and Cochrane Oral Health Group Trials Register databases for articles up to September 2016 with no language restriction. Local bone metabolism is subject to signals from systemic calciumâ phosphate homeostasis and bone remodeling. Three areas of interest were reviewed due to recent reported compromises in bone healing including the putative effects of (1) cholesterol, (2) hyperlipidemia, and (3) low vitamin D intake. Moreover, the prominent influence of osteocytes and immune cells is discussed as being key regulators during dental implant osseointegration and maintenance. These cells are of crucial importance in the presence of biofilm accumulation and their associated byproducts that leads to hard and soft tissue breakdown; the so called periâ implantitis. Factors that could negatively impact osteoclastogenesis or osteal macrophage activation should be monitored in future research including implant placement/torque protocols, bone characteristics, as well as meticulous maintenance programs to favor osseointegration and future longâ term stability and success of dental implants. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2075â 2089, 2017.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137387/1/jbma36060.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137387/2/jbma36060_am.pd

Brain Injury

The present two volume book "Brain Injury" is distinctive in its presentation and includes a wealth of updated information on many aspects in the field of brain injury. The Book is devoted to the pathogenesis of brain injury, concepts in cerebral blood flow and metabolism, investigative approaches and monitoring of brain injured, different protective mechanisms and recovery and management approach to these individuals, functional and endocrine aspects of brain injuries, approaches to rehabilitation of brain injured and preventive aspects of traumatic brain injuries. The collective contribution from experts in brain injury research area would be successfully conveyed to the readers and readers will find this book to be a valuable guide to further develop their understanding about brain injury

MODELLING AND VERIFICATION OF THERMOACOUSTIC MEDICAL IMAGING FROM NANOSCOPIC TO MACROSCOPIC RESOLUTIONS

In this thesis, three main questions regarding the potential of thermoacoustic imaging are answered: 1) what are the conventional resolution limitations of photoacoustic imaging and how can they be extended to enable high-resolution imaging, 2) Can photoacoustic imaging resolution be brought down to nanoscopic levels, and 3) As laser based photoacoustic imaging has been deployed with great success, is it also possible for other radiation to generate useful ultrasound signals for imaging? Whereas laser-induced photoacoustic tomography has been widely explored for a diverse range of biomedical contexts, there remain some fundamental limits to the resolution levels in which it can operate. Namely, the axial resolution of photoacoustic imaging remains restricted by the fact that ultrasonic transducers are not able to detect high-frequency signals that encode nanoscale resolution information. Therefore, there is a lingering question about how photoacoustic imaging can truly enter the realm of nanoscale imaging, as has been done by other modalities such as STED microscopy, structured illumination microscopy, and STORM microscopy. It is believed that laser-based detection in lieu of a transducer may enable a super-resolution photoacoustic imaging modality. However, there remain important questions about the reach and feasibility of nanoscale photoacoustic imaging. Specifically: will highly focused lasers directed at single cells result in thermal damage of biological samples? Will the axial imaging resolution of laser based detection truly be able to overcome the conventional optical diffraction limit of ~200nm? Will optical detection be sensitive enough to detect photoacoustic signals? Consequently, models are developed for thermoacoustic imaging for nanoscale imaging at super-resolutions exceeding that of the optical diffraction limit (~200nm), that show the potential for thermoacoustic imaging to enable super-resolution imaging of single cells. The models confirm that such imaging is possible while simultaneously ensuring the thermal safety of cells as the laser-induced temperature rise of such imaging is only within mK, potentially allowing for high-resolution imaging in vivo. It is also confirmed that a laser of 7ps duration should generate frequencies high enough to enable super-resolutions. Models are also developed for the estimation of the sensitivity and resolution of these high-resolution imaging, and it is predicted that super-resolution photoacoustic imaging may be able to image at axial resolutions of 10nm at noise equivalent number of molecules of 292 in the case of imaging hemoglobin in red blood cells. A length-scale and time-scale generalizable simulation workflow is developed and deployed to generate simulated images of super-resolution photoacoustic imaging, showing the potential of 3D super-resolution achievable via thermoacoustic imaging. This numerical simulation workflow is generalizable to multiple length scales as well as to other sources of radiation. The model predictions regarding detectable high frequency photoacoustic signal generation is experimentally confirmed via the creation and testing of a pump-probe based preliminary photoacoustic imaging system. The system is shown to be capable of detecting a clear and repeatable signal. Acquired A-lines from this system confirm that GHz frequencies can be detected using pump-probe detection in photoacoustics, thereby opening the door for nanoscale photoacoustic imaging However, the experimental results also demonstrate that feasible and convenient nanoscale imaging will require a more stable laser than is available, as pulse to pulse intensity fluctuations in the laser greatly limit the imaging speed and necessary number of averages for a single A-line scan. The developed models show promise and use towards the development of novel thermoacoustic imaging modalities and can be deployed to assess feasibility of different configurations of thermoacoustic imaging prior to the expenditure of resources on experimental realization. In this way, the developed models have the potential to enable the development of various thermoacoustic imaging modalities via a single generalizable framework through which imaging characteristics can be predicted at multiple length and time scales