Market application of a novel stent-based patency monitor to the management of ischemic vascular disease

Thesis (S.M.)--Harvard-MIT Division of Health Sciences and Technology; and, (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management, 2006.Includes bibliographical references (p. 79-82).The use of stents following angioplasty in ischemic arterial beds is limited by complications and continuing vascular deterioration. A phenomenon called stent restenosis post procedure exists which puts patients at a relatively high risk for vessel stenosis and occlusion. Stent restenosis may eventually lead to clinical symptoms such as myocardial infarction, stroke or limb loss, and if overlooked might lead to death. Within five years of stenting, a significant portion of patients require additional surgical intervention. A novel stent-based, implantable, and wireless approach for real-time monitoring of vessel patency at the site of coronary stents is proposed, will provide a measure of efficacy of stenting and of the pharmacologic regiment to mitigate the risk of vessel stenosis and narrowing due to the underlying. The purpose of this thesis is to explore and test the Hypotheses that there is a market for a direct, non-invasive monitoring of vessel patency at the site of a coronary stent; and that an implantable, wireless, stent-based device to monitor blood flow rate through a coronary stent can be designed and built.(cont.) A literature survey of late clinical studies and the opinion of numerous specialist clinicians collected in interviews and preliminary questionnaire, demonstrate sufficient clinical ambiguity regarding the safety of coronary stents, including Drug-Eluting Stents (DES) portrait an underserved clinical need to justify the introduction of a direct, non-invasive modality for post-op monitoring of vessel patency at the site of a coronary stent.by Baruch Schori.M.B.A.S.M

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

Ultrasound Orientation Sensor

Ultrasound (US) is a painless method of gaining a visual representation of the internal structures of a human body. It is used to look for diseases and other abnormalities. In effort to minimize and eliminate the amount of error generated by the operation of an US machine, a team of WPI students conducted research into the causes and reasons as to why these problems are not resolved. Ultimately, the team approached the problem through the use of an inertial measurement unit (IMU), and the development of a graphical user interface to track the orientation of an US probe. The results supported that feedback regarding probe orientation can increase the ability to reproduce ultrasound images

Advances in Bioengineering

The technological approach and the high level of innovation make bioengineering extremely dynamic and this forces researchers to continuous updating. It involves the publication of the results of the latest scientific research. This book covers a wide range of aspects and issues related to advances in bioengineering research with a particular focus on innovative technologies and applications. The book consists of 13 scientific contributions divided in four sections: Materials Science; Biosensors. Electronics and Telemetry; Light Therapy; Computing and Analysis Techniques

Ultrasound Orientation Sensor

Ultrasound (US) is a painless method of gaining a visual representation of the internal structures of a human body. It is used to look for diseases and other abnormalities. In effort to minimize and eliminate the amount of error generated by the operation of an US machine, a team of WPI students conducted research into the causes and reasons as to why these problems are not resolved. Ultimately, the team approached the problem through the use of an inertial measurement unit (IMU), and the development of a graphical user interface to track the orientation of an US probe. The results supported that feedback regarding probe orientation can increase the ability to reproduce ultrasound images

Optical Diagnostics in Human Diseases

Optical technologies provide unique opportunities for the diagnosis of various pathological disorders. The range of biophotonics applications in clinical practice is considerably wide given that the optical properties of biological tissues are subject to significant changes during disease progression. Due to the small size of studied objects (from μm to mm) and despite some minimum restrictions (low-intensity light is used), these technologies have great diagnostic potential both as an additional tool and in cases of separate use, for example, to assess conditions affecting microcirculatory bed and tissue viability. This Special Issue presents topical articles by researchers engaged in the development of new methods and devices for optical non-invasive diagnostics in various fields of medicine. Several studies in this Special Issue demonstrate new information relevant to surgical procedures, especially in oncology and gynecology. Two articles are dedicated to the topical problem of breast cancer early detection, including during surgery. One of the articles is devoted to urology, namely to the problem of chronic or recurrent episodic urethral pain. Several works describe the studies in otolaryngology and dentistry. One of the studies is devoted to diagnosing liver diseases. A number of articles contribute to the studying of the alterations caused by diabetes mellitus and cardiovascular diseases. The results of all the presented articles reflect novel innovative research and emerging ideas in optical non-invasive diagnostics aimed at their wider translation into clinical practice

Director's Discretionary Fund Report for Fiscal Year 1996

Topics covered include: Waterproofing the Space Shuttle tiles, thermal protection system for Reusable Launch Vehicles, computer modeling of the thermal conductivity of cometary ice, effects of ozone depletion and ultraviolet radiation on plants, a novel telemetric biosensor to monitor blood pH on-line, ion mobility in polymer electrolytes for lithium-polymer batteries, a microwave-pumped far infrared photoconductor, and a new method for measuring cloud liquid vapor using near infrared remote sensing. Also included: laser-spectroscopic instrument for turbulence measurement, remote sensing of aircraft contrails using a field portable imaging interferometer, development of a silicon-micromachined gas chromatography system for determination of planetary surface composition, planar Doppler velocimetry, chaos in interstellar chemistry, and a limited pressure cycle engine for high-speed output

Multimodal photoacoustic remote sensing (PARS) microscopy combined with swept-source optical coherence tomography (SS-OCT) for in-vivo, non-contact, functional and structural ophthalmic imaging applications

Ophthalmic imaging has long played an important role in the understanding, diagnosis, and treatment of a wide variety of ocular disorders. Currently, available clinical ophthalmic imaging instruments are primarily optical-based, including slit-lamp microscopy, fundus photography, confocal microscopy, scanning laser ophthalmoscopy, and optical coherence tomography (OCT). The development of these imaging instruments has greatly extended our ability to evaluate the ocular environment. Studies have shown that at least 40% of blinding disorders in the United States are either preventable or treatable with timely diagnosis and intervention. OCT is a state-of-the-art imaging technique extensively used in preclinical and clinical applications for imaging both anterior and posterior parts of the eye. OCT has become a standard of care for the assessment and treatment of most ocular conditions. The technology enables non-contact, high-speed, cross-sectional imaging over a large field of view with submicron resolutions. In eye imaging applications, functional extensions of OCT such as spectroscopic OCT and Doppler OCT have been applied to provide a better understanding of tissue activity. Spectroscopic OCT is usually achieved through OCT systems in the visible spectral range, and it enables the amount of light absorption inside the ocular environment to be measured. This indirect optical absorption measurement is used to estimate the amount of ocular oxygen saturation (SO2) which is a well-known biomarker in prevalent eye diseases including diabetic retinopathy, glaucoma, and retinal vein occlusions. Despite all the advancements in functional spectroscopic OCT methods, they still rely primarily on measuring the backscattered photons to quantify the absorption of chromophores inside the tissue. Therefore, they are sensitive to local geometrical parameters, such as retinal thickness, vessel diameters, and retinal pigmentation, and may result in biased estimations. Of the various optical imaging modalities, photoacoustic imaging (PAI) offers unique imaging contrast of optical absorption because PAI can image any target that absorbs light energy. This unique imaging ability makes PAI a favorable candidate for various functional and molecular imaging applications as well as for measuring chromophore concentration. Over the past decade, photoacoustic ophthalmoscopy has been applied for visualizing hemoglobin and melanin content in ocular tissue, quantifying ocular SO2, and measuring the metabolic rate of oxygen consumption (MRO2). Despite all these advantages offered by PAI devices, a major limitation arises from their need to be in contact with the ocular tissues. This physical contact may increase the risk of infection and cause patient discomfort. Furthermore, this contact-based imaging approach applies pressure to the eye and introduces barriers to oxygen diffusion. Thus, it has a crucial influence on the physiological and pathophysiological balance of ocular vasculature function, and it is not capable of studying dynamic processes under normal conditions. To overcome these limitations and to benefit from the numerous advantages offered by photoacoustic ophthalmoscopy, non-contact detection of photoacoustic signals has been a long-lasting goal in the field of ocular imaging. In 2017 Haji Reza et al. developed photoacoustic remote sensing (PARS) for non-contact, non-interferometric detection of photoacoustic signals. PARS is the non-contact, all-optical version of optical-resolution photoacoustic microscopy (OR-PAM), where the acoustically coupled ultrasound transducer is replaced with a co-focused probe beam. This all-optical detection scheme allows the system to measure the photoacoustic pressure waves at the subsurface origin where the pressure is at a maximum. In a very short time, PARS technology has proven its potential for various biomedical applications, including label-free histological imaging, SO2 mapping, and angiogenesis imaging. PARS is an ideal companion for OCT in ophthalmic applications, where the depth-resolved, detailed scattering information of OCT is well complemented by rich absorption information of PARS. This combined multimodal imaging technology has the potential to provide chromophore selective absorption contrast in concert with depth-resolved scattering contrast in the ocular environment. The main goals of this PhD project are to: • Develop a photoacoustic remote sensing microscopy system for in-vivo, non-contact ophthalmic imaging. This is the first time a non-contact photoacoustic imaging has been used for in-vivo imaging of the eye. • Develop a robust and temporally stable multiwavelength light source for functional photoacoustic imaging applications. • Develop a multimodal PARS-OCT imaging system that can image in-vivo and record, simultaneously, functional, and structural information in the anterior segment of a rodent eye. This is the first time a multiwavelength non-contact photoacoustic system is used for in-vivo measurement of oxygen saturation in the ocular environment. • Develop and modify the multimodal PARS-OCT imaging system for non-contact, in-vivo, functional, and structural imaging of the posterior part of the rodent eye

Optical Methods in Sensing and Imaging for Medical and Biological Applications

The recent advances in optical sources and detectors have opened up new opportunities for sensing and imaging techniques which can be successfully used in biomedical and healthcare applications. This book, entitled ‘Optical Methods in Sensing and Imaging for Medical and Biological Applications’, focuses on various aspects of the research and development related to these areas. The book will be a valuable source of information presenting the recent advances in optical methods and novel techniques, as well as their applications in the fields of biomedicine and healthcare, to anyone interested in this subject

Development of a hybrid microwave-optical system to monitor human thermoregulation

Warming of human tissue causes vasodilation and therefore, increase in blood volume. Such thermal responses allow the assessment of hemodynamics in the tissue, providing physiological and clinically important information of the diagnosed subject. Local warming is often accomplished on the skin because of its accessibility and simplicity. To allow the investigation into deeper tissue such as the muscle, an innovative hybrid microwave-optical system has been developed. This comprises of a microwave system, an optical monitoring and cooling system. The tissue warming is induced by a novel microwave applicator, which was based on microstrip patch design operating at 2.45 GHz with a superstrate interface layer to improve the coupling of electromagnetic (EM) waves into the skin. The active cooling was introduced to reduce skin heating. While the optical sensors based on Near-Infrared Spectroscopy (NIRS), was used to measure the changes in tissue oxygenation including the muscle. This thesis demonstrates the development procedure, covering the design and operation of the entire system. Moreover, the majority of the work is based on the four developed applicators, where each design was evaluated using EM and thermal simulation based on numerical phantoms. The study evaluates the distribution of absorbed EM energy in the tissue known as the specific absorption rate (SAR). The applicators are developed in the following order: (i) Applicator I was fabricated for preliminary study for general tissue heating with the integrated optical probes. This early study provided an insight to the importance of superstrate thickness and material. (ii) Applicator II, which introduces a new approach to skin cooling based on Thermoelectric Coolers (TEC) and high thermal conductive superstrate. This design could cool the skin and monitor tissue oxygenation, skin perfusion and temperature. (iii) Applicator III was an updated model of the predecessor, resolving cooling configuration and the discrepancy in operating frequency, and was capable of minimising skin heating effectively (iv) Circularly polarized (CP) Applicator aimed at reduction of the SAR in the superficial layer, and hence skin heating. The simulated thermal study of all developed applicators was validated with exvivo (mimicked phantom) and in-vivo experimental trials. The measurements and the simulation model were in agreement, apart from the CP applicator due to the complexity of measurement. The results from the phantom and human calf indicated superficial heating was reduced by about 5.0-6.0 ° C when skin cooling was applied, while the temperature change in muscle was not significantly affected. The measurement with mimicked tissue showed the applicator was capable of elevating muscle temperature by approximately 3.0-4.0 ° C. This is a sufficient increase to cause tissue dilation, and therefore, change in the thermal response. The hybrid microwave-optical system has been developed and examined on three human calves during in-vivo physiological study. The results using Applicator II illustrated that the device can successfully stimulate and measure thermal responses in terms of oxy/deoxy/total haemoglobin concentrations changes ( HbO2/ HHb/ HbT). The slope (rate of change) of HbT curve during microwave exposure is defined as the thermal response. This parameter is essential in studying physiological responses between different subject, particularly in vascular diseases, transplanted free flaps and other conditions, including chronic spinal cord injury. Subjects with such conditions will have a distinguishable response to tissue heating than a healthy subject. The monitored haemodynamic signals of Applicator II are primarily based on superficial responses. However, measurements with Applicator III showed the potential of the applicator. The measured thermal response was 0.83 10 3×10⁻³ μM/s without skin cooling, which was dedicated by skin heating. The introduced cooling system has reduced the skin temperature and maintained the local skin micro-circulation, which was monitored with the secondary optical system based on Laser Doppler Flowmetry (LDF). This probe measures blood flow at superficial depth, and consequently, was used as a validation tool to demonstrate the cooling efficiency. The measured thermal response with skin over-cooling was -0.08 10 3×10⁻³ μM/s. The negative response indicates arterial constriction, and therefore, the skin heat was eliminated while the simulations study to indicate the muscle temperature was elevated by 3 ° C. However, the response was dominant by the superficial response. Obtaining a response from muscle only was challenging and currently being solved in numerous applicator and cooling technique, which have been presented in the thesis