Concurrent application of TMS and near-infrared optical imaging: methodological considerations and potential artifacts

PubMed Central

Parks, Nathan A.

2013-01-01

The simultaneous application of transcranial magnetic stimulation (TMS) with non-invasive neuroimaging provides a powerful method for investigating functional connectivity in the human brain and the causal relationships between areas in distributed brain networks. TMS has been combined with numerous neuroimaging techniques including, electroencephalography (EEG), functional magnetic resonance imaging (fMRI), and positron emission tomography (PET). Recent work has also demonstrated the feasibility and utility of combining TMS with non-invasive near-infrared optical imaging techniques, functional near-infrared spectroscopy (fNIRS) and the event-related optical signal (EROS). Simultaneous TMS and optical imaging affords a number of advantages over other neuroimaging methods but also involves a unique set of methodological challenges and considerations. This paper describes the methodology of concurrently performing optical imaging during the administration of TMS, focusing on experimental design, potential artifacts, and approaches to controlling for these artifacts. PMID:24065911

Non-invasive detection of iron deficiency by fluorescence measurement of erythrocyte zinc protoporphyrin in the lip

PubMed Central

Hennig, Georg; Homann, Christian; Teksan, Ilknur; Hasbargen, Uwe; Hasmüller, Stephan; Holdt, Lesca M.; Khaled, Nadia; Sroka, Ronald; Stauch, Thomas; Stepp, Herbert; Vogeser, Michael; Brittenham, Gary M.

2016-01-01

Worldwide, more individuals have iron deficiency than any other health problem. Most of those affected are unaware of their lack of iron, in part because detection of iron deficiency has required a blood sample. Here we report a non-invasive method to optically measure an established indicator of iron status, red blood cell zinc protoporphyrin, in the microcirculation of the lower lip. An optical fibre probe is used to illuminate the lip and acquire fluorescence emission spectra in ∼1 min. Dual-wavelength excitation with spectral fitting is used to distinguish the faint zinc protoporphyrin fluorescence from the much greater tissue background fluorescence, providing immediate results. In 56 women, 35 of whom were iron-deficient, the sensitivity and specificity of optical non-invasive detection of iron deficiency were 97% and 90%, respectively. This fluorescence method potentially provides a rapid, easy to use means for point-of-care screening for iron deficiency in resource-limited settings lacking laboratory infrastructure. PMID:26883939

New optical method for enhanced detection of colon cancer by capsule endoscopy

NASA Astrophysics Data System (ADS)

AnkriEqually Contributed, Rinat; Peretz, Dolev; Motiei, Menachem; Sella-Tavor, Osnat; Popovtzer, Rachela

2013-09-01

PillCam®COLON capsule endoscopy (CE), a non-invasive diagnostic tool of the digestive tract, has dramatically changed the diagnostic approach and has become an attractive alternative to the conventional colonoscopy for early detection of colorectal cancer. However, despite the significant progress and non-invasive detection capability, studies have shown that its sensitivity and specificity is lower than that of conventional colonoscopy. This work presents a new optical detection method, specifically tailored to colon cancer detection and based on the well-known optical properties of immune-conjugated gold nanorods (GNRs). We show, on a colon cancer model implanted in a chick chorioallantoic membrane (CAM), that this detection method enables conclusive differentiation between cancerous and normal tissues, where neither the distance between the light source and the intestinal wall, nor the background signal, affects the monitored signal. This optical method, which can easily be integrated in CE, is expected to reduce false positive and false negative results and improve identification of tumors and micro metastases.

Saliva surface-enhanced Raman spectroscopy for noninvasive optical detection of nasopharyngeal cancer

NASA Astrophysics Data System (ADS)

Lin, Xueliang; Ge, Xiaosong; Xu, Zhihong; Zheng, Zuci; Huang, Wei; Hong, Quanxing; Lin, Duo

2016-10-01

The early cancer detection is of great significance to increase the patient's survival rate and reduce the risk of cancer development. Surface enhanced Raman spectroscopy (SERS) technique, a rapid, convenient, nondestructive optical detection method, can provide a characteristic "fingerprint" information of target substances, even achieving single molecule detection. Its ultra-high detection sensitivity has made it become one of the most potential biochemical detection methods. Saliva, a multi-constituent oral fluid, contains the bio-markers which is capable of reflecting the systemic health condition of human, showing promising potential as an effect medium for disease monitoring. Compared with the serum samples, the collection and processing of saliva is safer, more convenient and noninvasive. Thus, saliva test is becoming the hotspot issues of the noninvasive cancer research field. This review highlights and analyzes current application progress within the field of SERS saliva test in cancer detection. Meanwhile, the primary research results of SERS saliva for the noninvasive differentiation of nasopharyngeal cancer, normal and rhinitis obtained by our group are shown.

Noninvasive Intracranial Pressure Monitoring for Severe Traumatic Brain Injury in Children: A Concise Update on Current Methods.

PubMed

Narayan, Vinayak; Mohammed, Nasser; Savardekar, Amey R; Patra, Devi Prasad; Notarianni, Christina; Nanda, Anil

2018-06-01

Traumatic brain injury (TBI) is a leading cause of pediatric morbidity and mortality worldwide and intracranial pressure (ICP) monitoring plays a crucial role in its management. Based on existing literature, we review the current practicing noninvasive ICP monitoring devices and their accuracy in predicting increased ICP in pediatric TBI. A thorough literature search was conducted on PubMed, Medline, and the Cochrane database, articles were selected systematically and reviewed completely, and relevant data were summarized and discussed. A total of 27 articles pertaining to pediatric TBI were included and reviewed. We found various modalities of noninvasive ICP monitoring devices used over the last few years. The noninvasive modalities so far attempted in pediatric TBI and so reviewed here are transcranial Doppler, optic nerve sheath diameter, otoacoustic emission, near-infrared spectroscopy, contrast-enhanced ultrasonography, and quantitative pupillometry. Invasive monitoring methods are the current gold standard for monitoring ICP; however, complications caused by their invasive nature are of concern. Of all the noninvasive methods based on the literature, we found transcranial Doppler and optic nerve sheath diameter assessment to be the best tools to monitor ICP in pediatric TBI. The promising results and developments of noninvasive ICP monitoring modalities with its ideal features of high sensitivity, diagnostic accuracy, and simple acquisition technique may make it the future of neurointensive monitoring in pediatric TBI. Copyright © 2018 Elsevier Inc. All rights reserved.

A study on new method of noninvasive esophageal venous pressure measurement based on the airflow and laser detection technology.

PubMed

Hu, Chenghuan; Huang, Feizhou; Zhang, Rui; Zhu, Shaihong; Nie, Wanpin; Liu, Xunyang; Liu, Yinglong; Li, Peng

2015-01-01

Using optics combined with automatic control and computer real-time image detection technology, a novel noninvasive method of noncontact pressure manometry was developed based on the airflow and laser detection technology in this study. The new esophageal venous pressure measurement system was tested in-vitro experiments. A stable and adjustable pulse stream was produced from a self-developed pump and a laser emitting apparatus could generate optical signals which can be captured by image acquisition and analysis system program. A synchronization system simultaneous measured the changes of air pressure and the deformation of the vein wall to capture the vascular deformation while simultaneously record the current pressure value. The results of this study indicated that the pressure values tested by the new method have good correlation with the actual pressure value in animal experiments. The new method of noninvasive pressure measurement based on the airflow and laser detection technology is accurate, feasible, repeatable and has a good application prospects.

Optical assessment of skin carotenoid status as a biomarker of vegetable and fruit intake

USDA-ARS?s Scientific Manuscript database

Resonance Raman spectroscopy (RRS) and reflection spectroscopy (RS) are optical methods applicable to the non-invasive detection of carotenoids in human skin. RRS is the older, more thoroughly validated method, whereas RS is newer and has several advantages. Since collective skin carotenoid levels...

Noninvasive monitoring of photodynamic therapy on skin neoplastic lesions using the optical attenuation coefficient measured by optical coherence tomography

NASA Astrophysics Data System (ADS)

Goulart, Viviane P.; dos Santos, Moisés O.; Latrive, Anne; Freitas, Anderson Z.; Correa, Luciana; Zezell, Denise M.

2015-05-01

Photodynamic therapy (PDT) has become a promising alternative for treatment of skin lesions such as squamous cell carcinoma. We propose a method to monitor the effects of PDT in a noninvasive way by using the optical attenuation coefficient (OAC) calculated from optical coherence tomography (OCT) images. We conducted a study on mice with chemically induced neoplastic lesions and performed PDT on these lesions using homemade photosensitizers. The response of neoplastic lesions to therapy was monitored using, at the same time, macroscopic clinical visualization, histopathological analysis, OCT imaging, and OCT-based attenuation coefficient measurement. Results with all four modalities demonstrated a positive response to treatment. The attenuation coefficient was found to be 1.4 higher in skin lesions than in healthy tissue and it decreased after therapy. This study shows that the OAC is a potential tool to noninvasively assess the evolution of skin neoplastic lesions with time after treatment.

Optical remote sensing and correlation of office equipment functional state and stress levels via power quality disturbances inefficiencies

NASA Astrophysics Data System (ADS)

Sternberg, Oren; Bednarski, Valerie R.; Perez, Israel; Wheeland, Sara; Rockway, John D.

2016-09-01

Non-invasive optical techniques pertaining to the remote sensing of power quality disturbances (PQD) are part of an emerging technology field typically dominated by radio frequency (RF) and invasive-based techniques. Algorithms and methods to analyze and address PQD such as probabilistic neural networks and fully informed particle swarms have been explored in industry and academia. Such methods are tuned to work with RF equipment and electronics in existing power grids. As both commercial and defense assets are heavily power-dependent, understanding electrical transients and failure events using non-invasive detection techniques is crucial. In this paper we correlate power quality empirical models to the observed optical response. We also empirically demonstrate a first-order approach to map household, office and commercial equipment PQD to user functions and stress levels. We employ a physics-based image and signal processing approach, which demonstrates measured non-invasive (remote sensing) techniques to detect and map the base frequency associated with the power source to the various PQD on a calibrated source.

The way to universal and correct medical presentation of diagnostic informations for complex spectrophotometry noninvasive medical diagnostic systems

NASA Astrophysics Data System (ADS)

Rogatkin, Dmitrii A.; Tchernyi, Vladimir V.

2003-07-01

The optical noninvasive diagnostic systems are now widely applied and investigated in different areas of medicine. One of the such techniques is the noninvasive spectrophotometry, the complex diagnostic technique consisting on elastic scattering spectroscopy, absorption spectroscopy, fluorescent diagnostics, photoplethismography, etc. Today a lot of real optical diagnostic systems indicate the technical parameters and physical data only as a result of the diagnostic procedure. But, it is clear that for the medical staff the more convenient medical information is needed. This presentation lights the general way for development a diagnostic system"s software, which can produce the full processing of the diagnostic data from a physical to a medical level. It is shown, that this process is a multilevel (3-level) procedure and the main diagnostic result for noninvasive spectrophotometry methods, the biochemical and morphological composition of the tested tissues, arises in it on a second level of calculations.

Noninvasive blood pressure measurement scheme based on optical fiber sensor

NASA Astrophysics Data System (ADS)

Liu, Xianxuan; Yuan, Xueguang; Zhang, Yangan

2016-10-01

Optical fiber sensing has many advantages, such as volume small, light quality, low loss, strong in anti-jamming. Since the invention of the optical fiber sensing technology in 1977, optical fiber sensing technology has been applied in the military, national defense, aerospace, industrial, medical and other fields in recent years, and made a great contribution to parameter measurement in the environment under the limited condition .With the rapid development of computer, network system, the intelligent optical fiber sensing technology, the sensor technology, the combination of computer and communication technology , the detection, diagnosis and analysis can be automatically and efficiently completed. In this work, we proposed a noninvasive blood pressure detection and analysis scheme which uses optical fiber sensor. Optical fiber sensing system mainly includes the light source, optical fiber, optical detector, optical modulator, the signal processing module and so on. wavelength optical signals were led into the optical fiber sensor and the signals reflected by the human body surface were detected. By comparing actual testing data with the data got by traditional way to measure the blood pressure we can establish models for predicting the blood pressure and achieve noninvasive blood pressure measurement by using spectrum analysis technology. Blood pressure measurement method based on optical fiber sensing system is faster and more convenient than traditional way, and it can get accurate analysis results in a shorter period of time than before, so it can efficiently reduce the time cost and manpower cost.

An exploration of the biomedical optics course construction of undergraduate biomedical engineering program in medical colleges

NASA Astrophysics Data System (ADS)

Guo, Shijun; Lyu, Jie; Zhang, Peiming

2017-08-01

In this paper, the teaching goals, teaching contents and teaching methods in biomedical optics course construction are discussed. From the dimension of teaching goals, students should master the principle of optical inspection on the human body, diagnosis and treatment of methodology and instruments, through the study of the theory and practice of this course, and can utilize biomedical optics methods to solve practical problems in the clinical medical engineering practice. From the dimension of teaching contents, based on the characteristics of biomedical engineering in medical colleges, the organic integration of engineering aspects, medical optical instruments, and biomedical aspects dispersed in human anatomy, human physiology, clinical medicine fundamental related to the biomedical optics is build. Noninvasive measurement of the human body composition and noninvasive optical imaging of the human body were taken as actual problems in biomedical optics fields. Typical medical applications such as eye optics and laser medicine were also integrated into the theory and practice teaching. From the dimension of teaching methods, referencing to organ-system based medical teaching mode, optical principle and instrument principle were taught by teachers from school of medical instruments, and the histological characteristics and clinical actual need in areas such as digestive diseases and urinary surgery were taught by teachers from school of basic medicine or clinical medicine of medical colleges. Furthermore, clinical application guidance would be provided by physician and surgeons in hospitals.

The importance of optical methods for non-invasive measurements in the skin care industry

NASA Astrophysics Data System (ADS)

Stamatas, Georgios N.

2010-02-01

Pharmaceutical and cosmetic industries are concerned with treating skin disease, as well as maintaining and promoting skin health. They are dealing with a unique tissue that defines our body in space. As such, skin provides not only the natural boundary with the environment inhibiting body dehydration as well as penetration of exogenous aggressors to the body, it is also ideally situated for optical measurements. A plurality of spectroscopic and imaging methods is being used to understand skin physiology and pathology and document the effects of topically applied products on the skin. The obvious advantage of such methods over traditional biopsy techniques is the ability to measure the cutaneous tissue in vivo and non-invasively. In this work, we will review such applications of various spectroscopy and imaging methods in skin research that is of interest the cosmetic and pharmaceutical industry. Examples will be given on the importance of optical techniques in acquiring new insights about acne pathogenesis and infant skin development.

Non-invasive measurements of tissue hemodynamics with hybrid diffuse optical methods

NASA Astrophysics Data System (ADS)

Durduran, Turgut

Diffuse optical techniques were used to measure hemodynamics of tissues non-invasively. Spectroscopy and tomography of the brain, muscle and implanted tumors were carried out in animal models and humans. Two qualitatively different methods, diffuse optical tomography and diffuse correlation tomography, were hybridized permitting simultaneous measurement of total hemoglobin concentration, blood oxygen saturation and blood flow. This combination of information was processed further to derive estimates of oxygen metabolism (e.g. CMRO 2) in tissue. The diffuse correlation measurements of blood flow were demonstrated in human tissues, for the first time, demonstrating continous, non-invasive imaging of oxygen metabolism in large tissue volumes several centimeters below the tissue surface. The bulk of these investigations focussed on cerebral hemodynamics. Extensive validation of this methodology was carried out in in vivo rat brain models. Three dimensional images of deep tissue hemodynamics in middle cerebral artery occlusion and cortical spreading depression (CSD) were obtained. CSD hemodynamics were found to depend strongly on partial pressure of carbon dioxide. The technique was then adapted for measurement of human brain. All optical spectroscopic measurements of CMRO2 during functional activation were obtained through intact human skull non-invasively. Finally, a high spatio-temporal resolution measurement of cerebral blood flow due to somatosensory cortex activation following electrical forepaw stimulation in rats was carried out with laser speckle flowmetry. New analysis methods were introduced for laser speckle flowmetry. In other organs, deep tissue hemodynamics were measured on human calf muscle during exercise and cuff-ischemia and were shown to have some clinical utility for peripheral vascular disease. In mice tumor models, the measured hemodynamics were shown to be predictive of photodynamic therapy efficacy, again suggesting promise of clinical utility. In total, the research has pioneered the development of diffuse optical measurements of blood flow, oxygenation and oxygen metabolism in a large range of research and clinical applications.

HUMAN EYE OPTICS: Determination of positions of optical elements of the human eye

NASA Astrophysics Data System (ADS)

Galetskii, S. O.; Cherezova, T. Yu

2009-02-01

An original method for noninvasive determining the positions of elements of intraocular optics is proposed. The analytic dependence of the measurement error on the optical-scheme parameters and the restriction in distance from the element being measured are determined within the framework of the method proposed. It is shown that the method can be efficiently used for determining the position of elements in the classical Gullstrand eye model and personalised eye models. The positions of six optical surfaces of the Gullstrand eye model and four optical surfaces of the personalised eye model can be determined with an error of less than 0.25 mm.

Towards non-invasive characterization of breast cancer and cancer metabolism with diffuse optics

PubMed Central

Busch, David R.; Choe, Regine; Durduran, Turgut; Yodh, Arjun G.

2013-01-01

We review recent developments in diffuse optical imaging and monitoring of breast cancer, i.e. optical mammography. Optical mammography permits non-invasive, safe and frequent measurement of tissue hemodynamics oxygen metabolism and components (lipids, water, etc.), the development of new compound indices indicative of the risk and malignancy, and holds potential for frequent non-invasive longitudinal monitoring of therapy progression. PMID:24244206

Skin carotenoids as biomarker for vegetable and fruit intake: Validation of the reflection-spectroscopy based “Veggie Meter”

USDA-ARS?s Scientific Manuscript database

Skin is a relatively stable storage medium for carotenoids; non-invasive optical measurements of carotenoids in this tissue via Resonance Raman spectroscopy (RRS) serve as a non-invasive biomarker for fruit and vegetable (F/V) intake. The RRS method has been validated with HPLC-based measurements of...

Sensor system for non-invasive optical carboxy-and methemoglobin determination

NASA Astrophysics Data System (ADS)

Timm, Ulrich; Gewiss, Helge; Kraitl, Jens; Brock, Beate; Ewald, Hartmut

2017-02-01

The pulse oximetry is a non-invasive method to monitor the oxygen saturation and is clinically used for many years. However this technology has some limitations. In case of the presence of dysfunctional hemoglobin derivatives as carboxyhemoglobin (COHb) or methemoglobin (MetHb) the readings of the pulse oximeter are distorted. This erroneous diagnosis of the patient's status can result in a life threatening situation. This paper will describe a sensor system for noninvasive determination of carboxy- and methemoglobin.

Stiffness of RBC optical confinement affected by optical clearing

NASA Astrophysics Data System (ADS)

Grishin, Oleg V.; Fedosov, Ivan V.; Tuchin, Valery V.

2017-03-01

In vivo optical trapping is a novel applied direction of an optical manipulation, which enables one to noninvasive measurement of mechanical properties of cells and tissues in living animals directly. But an application area of this direction is limited because strong scattering of many biological tissues. An optical clearing enables one to decrease the scattering and therefore increase a depth of light penetration, decrease a distortion of light beam, improve a resolution in imaging applications. Now novel methods had appeared for a measurement an optical clearing degree at a cellular level. But these methods aren't applicable in vivo. In this paper we present novel measurement method of estimate of the optical clearing, which are based on a measurement of optical trap stiffness. Our method may be applicable in vivo.

Development of Noninvasive Blood Glucose Sensor Using the Infrared Spectroscopy

NASA Astrophysics Data System (ADS)

Fujita, Keiichi; Tamura, Kazuto; Kaneko, Wataru; Ishizawa, Hiroaki; Toba, Eiji

Recently, diabetics have been steadily increasing, because change of diet, lack of exercise, increase an alcoholic intake, and increase a stress. It is a very serious problem for us. About 23.6 millions of people in Japan approach the danger of diabetes. Therefore, it is necessary to get insulin injection. And they have to measure blood glucose again and again a day. So, they are burden too heavy. This paper describes a new noninvasive measurement of blood glucose based on optical sensing. This uses Fourier transform infrared spectroscopy of attenuated total reflection. Non-invasive measurement was carried out by using 3 methods. And standard error of prediction is about ±20mg/dl by 3 method. This paper also describes practical application of this method.

Nondestructive surface analysis for material research using fiber optic vibrational spectroscopy

NASA Astrophysics Data System (ADS)

Afanasyeva, Natalia I.

2001-11-01

The advanced methods of fiber optical vibrational spectroscopy (FOVS) has been developed in conjunction with interferometer and low-loss, flexible, and nontoxic optical fibers, sensors, and probes. The combination of optical fibers and sensors with Fourier Transform (FT) spectrometer has been used in the range from 2.5 to 12micrometers . This technique serves as an ideal diagnostic tool for surface analysis of numerous and various diverse materials such as complex structured materials, fluids, coatings, implants, living cells, plants, and tissue. Such surfaces as well as living tissue or plants are very difficult to investigate in vivo by traditional FT infrared or Raman spectroscopy methods. The FOVS technique is nondestructive, noninvasive, fast (15 sec) and capable of operating in remote sampling regime (up to a fiber length of 3m). Fourier transform infrared (FTIR) and Raman fiber optic spectroscopy operating with optical fibers has been suggested as a new powerful tool. These techniques are highly sensitive techniques for structural studies in material research and various applications during process analysis to determine molecular composition, chemical bonds, and molecular conformations. These techniques could be developed as a new tool for quality control of numerous materials as well as noninvasive biopsy.

Development of a non-invasive LED based device for adipose tissue thickness measurements in vivo

NASA Astrophysics Data System (ADS)

Volceka, K.; Jakovels, D.; Arina, Z.; Zaharans, J.; Kviesis, E.; Strode, A.; Svampe, E.; Ozolina-Moll, L.; Butnere, M. M.

2012-06-01

There are a number of techniques for body composition assessment in clinics and in field-surveys, but in all cases the applied methods have advantages and disadvantages. High precision imaging methods are available, though expensive and non-portable, however, the methods devised for the mass population, often suffer from the lack of precision. Therefore, the development of a safe, mobile, non-invasive, optical method that would be easy to perform, precise and low-cost, but also would offer an accurate assessment of subcutaneous adipose tissue (SAT) both in lean and in obese persons is required. Thereof, the diffuse optical spectroscopy is advantageous over the aforementioned techniques. A prototype device using an optical method for measurement of the SAT thickness in vivo has been developed. The probe contained multiple LEDs (660nm) distributed at various distances from the photo-detector which allow different light penetration depths into the subcutaneous tissue. The differences of the reflected light intensities were used to create a non-linear model, and the computed values were compared with the corresponding thicknesses of SAT, assessed by B-mode ultrasonography. The results show that with the optical system used in this study, accurate results of different SAT thicknesses can be obtained, and imply a further potential for development of multispectral optical system to observe changes of SAT thickness as well as to determine the percentage of total body fat.

Optical spectroscopy for the detection of ischemic tissue injury

DOEpatents

Demos, Stavros [Livermore, CA; Fitzgerald, Jason [Sacramento, CA; Troppmann, Christoph [Sacramento, CA; Michalopoulou, Andromachi [Athens, GR

2009-09-08

An optical method and apparatus is utilized to quantify ischemic tissue and/or organ injury. Such a method and apparatus is non-invasive, non-traumatic, portable, and can make measurements in a matter of seconds. Moreover, such a method and apparatus can be realized through optical fiber probes, making it possible to take measurements of target organs deep within a patient's body. Such a technology provides a means of detecting and quantifying tissue injury in its early stages, before it is clinically apparent and before irreversible damage has occurred.

Single Cell Spectroscopy: Noninvasive Measures of Small-Scale Structure and Function

PubMed Central

Mousoulis, Charilaos; Xu, Xin; Reiter, David A.; Neu, Corey P.

2013-01-01

The advancement of spectroscopy methods attained through increases in sensitivity, and often with the coupling of complementary techniques, has enabled real-time structure and function measurements of single cells. The purpose of this review is to illustrate, in light of advances, the strengths and the weaknesses of these methods. Included also is an assessment of the impact of the experimental setup and conditions of each method on cellular function and integrity. A particular emphasis is placed on noninvasive and nondestructive techniques for achieving single cell detection, including nuclear magnetic resonance, in addition to physical, optical, and vibrational methods. PMID:23886910

Quantification of optical absorption coefficient from acoustic spectra in the optical diffusive regime using photoacoustic microscopy

NASA Astrophysics Data System (ADS)

Guo, Zijian; Favazza, Christopher; Wang, Lihong V.

2012-02-01

Photoacoustic (PA) tomography (PAT) can image optical absorption contrast with ultrasonic spatial resolution in the optical diffusive regime. Multi-wavelength PAT can noninvasively monitor hemoglobin oxygen saturation (sO2) with high sensitivity and fine spatial resolution. However, accurate quantification in PAT requires knowledge of the optical fluence distribution, acoustic wave attenuation, and detection system bandwidth. We propose a method to circumvent this requirement using acoustic spectra of PA signals acquired at two optical wavelengths. With the acoustic spectral method, the absorption coefficients of an oxygenated bovine blood phantom at 560 and 575 nm were quantified with errors of ><5%.

Real-time and non-invasive measurements of cell mechanical behaviour with optical coherence phase microscopy

NASA Astrophysics Data System (ADS)

Gillies, D.; Gamal, W.; Downes, A.; Reinwald, Y.; Yang, Y.; El Haj, A.; Bagnaninchi, P. O.

2017-02-01

There is an unmet need in tissue engineering for non-invasive, label-free monitoring of cell mechanical behaviour in their physiological environment. Here, we describe a novel optical coherence phase microscopy (OCPM) set-up which can map relative cell mechanical behaviour in monolayers and 3D systems non-invasively, and in real-time. 3T3 and MCF-7 cells were investigated, with MCF-7 demonstrating an increased response to hydrostatic stimulus indicating MCF-7 being softer than 3T3. Thus, OCPM shows the ability to provide qualitative data on cell mechanical behaviour. Quantitative measurements of 6% agarose beads have been taken with commercial Cell Scale Microsquisher system demonstrating that their mechanical properties are in the same order of magnitude of cells, indicating that this is an appropriate test sample for the novel method described.

Imaging bio-distribution of a topically applied dermatological cream on minipig skin using fluorescence lifetime imaging microscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Alex, Aneesh; Chaney, Eric J.; Criley, Jennifer M.; Spillman, Darold R.; Hutchison, Phaedra B.; Li, Joanne; Marjanovic, Marina; Frey, Steve; Cook, Steven; Boppart, Stephen A.; Arp, Zane A.

2017-02-01

Currently there is a lack of in vivo techniques to evaluate the spatial bio-distribution of dermal drugs over time without the need to take multiple serial biopsies. To address this gap, we investigated the use of multi-photon optical imaging methods to non-invasively track drug distribution on miniature pig (Species: Sus scrofa, Strain: Göttingen) skin in vivo. Minipig skin is the standard comparative research model to human skin, and is anatomically and functionally similar. We employed fluorescence lifetime imaging microscopy (FLIM) to visualize the spatial distribution and residency time of a topically applied experimental dermatological cream. This was made possible by the endogenous fluorescent optical properties of the experimental drug (fluorescence lifetime > 3000 ps). Two different drug formulations were applied on 2 minipigs for 7 consecutive days, with the control creams applied on the contralateral side, followed by 7 days of post-application monitoring using a multi-modal optical imaging system (MPTflex-CARS, JenLab, Germany). FLIM images were obtained from the treated regions 24 hr post-application from day 1 to day 14 that allowed visualization of cellular and sub-cellular features associated with different dermal layers non-invasively to a depth of 200 µm. Five punch biopsies per animal were obtained from the corresponding treated regions between days 8 and 14 for bioanalytical analysis and comparison with results obtained using FLIM. In conclusion, utilization of non-invasive optical biopsy methods for dermal drug evaluation can provide true longitudinal monitoring of drug spatial distribution, remove sampling limitations, and be more time-efficient compared to traditional methods.

Non-invasive method to detect the changes of glucose concentration in whole blood using photometric technique.

PubMed

Rajan, Shiny Amala Priya; Towe, Bruce C

2014-01-01

A non-invasive method is developed to monitor rapid changes in blood glucose levels in diabetic patients. The system depends on an optical cell built with a LED that emits light of wavelength 535nm, which is a peak absorbance of hemoglobin. As the glucose concentration in blood decreases, its osmolarity also decreases and the Red Blood Cells (RBCs) swell and decrease the path length absorption coefficient. Decreasing absorption coefficient increases the transmission of light through the whole blood. The system was tested with a constructed optical cell that held whole blood in a capillary tube. As expected the light transmitted to the photodiode increases with decreasing glucose concentration. The average response time of the system was between 30-40 seconds.

High sensitivity contrast enhanced optical coherence tomography for functional in vivo imaging

NASA Astrophysics Data System (ADS)

Liba, Orly; SoRelle, Elliott D.; Sen, Debasish; de la Zerda, Adam

2017-02-01

In this study, we developed and applied highly-scattering large gold nanorods (LGNRs) and custom spectral detection algorithms for high sensitivity contrast-enhanced optical coherence tomography (OCT). We were able to detect LGNRs at a concentration as low as 50 pM in blood. We used this approach for noninvasive 3D imaging of blood vessels deep in solid tumors in living mice. Additionally, we demonstrated multiplexed imaging of spectrally-distinct LGNRs that enabled observations of functional drainage in lymphatic networks. This method, which we call MOZART, provides a platform for molecular imaging and characterization of tissue noninvasively at cellular resolution.

Time-reversed ultrasonically encoded (TRUE) focusing for deep-tissue optogenetic modulation

NASA Astrophysics Data System (ADS)

Brake, Joshua; Ruan, Haowen; Robinson, J. Elliott; Liu, Yan; Gradinaru, Viviana; Yang, Changhuei

2018-02-01

The problem of optical scattering was long thought to fundamentally limit the depth at which light could be focused through turbid media such as fog or biological tissue. However, recent work in the field of wavefront shaping has demonstrated that by properly shaping the input light field, light can be noninvasively focused to desired locations deep inside scattering media. This has led to the development of several new techniques which have the potential to enhance the capabilities of existing optical tools in biomedicine. Unfortunately, extending these methods to living tissue has a number of challenges related to the requirements for noninvasive guidestar operation, speed, and focusing fidelity. Of existing wavefront shaping methods, time-reversed ultrasonically encoded (TRUE) focusing is well suited for applications in living tissue since it uses ultrasound as a guidestar which enables noninvasive operation and provides compatibility with optical phase conjugation for high-speed operation. In this paper, we will discuss the results of our recent work to apply TRUE focusing for optogenetic modulation, which enables enhanced optogenetic stimulation deep in tissue with a 4-fold spatial resolution improvement in 800-micron thick acute brain slices compared to conventional focusing, and summarize future directions to further extend the impact of wavefront shaping technologies in biomedicine.

Non-invasive diagnostic system and its opto-mechanical probe for combining confocal Raman spectroscopy and optical coherence tomography.

PubMed

Klemes, Jan; Kotzianova, Adela; Pokorny, Marek; Mojzes, Peter; Novak, Jindrich; Sukova, Lada; Demuth, Jaroslav; Vesely, Jaroslav; Sasek, Ladislav; Velebny, Vladimir

2017-11-01

Non-invasive optical diagnostic methods allow important information about studied systems to be obtained in a non-destructive way. Complete diagnosis requires information about the chemical composition as well as the morphological structure of a sample. We report on the development of an opto-mechanical probe that combines Raman spectroscopy (RS) and optical coherence tomography (OCT), two methods that provide all the crucial information needed for a non-invasive diagnosis. The aim of this paper is to introduce the technical design, construction and optimization of a dual opto-mechanical probe combining two in-house developed devices for confocal RS and OCT. The unique benefit of the probe is a gradual acquisition of OCT and RS data, which allows to use the acquired OCT images to pinpoint locations of interest for RS measurements. The parameters and the correct functioning of the probe were verified by RS scanning of various samples (silicon wafer and ex vivo tissue) based on their OCT images - lateral as well as depth scanning was performed. Both the OCT and RS systems were developed, optimized and tested with the ultimate aim of verifying the functionality of the probe. Picture: Schematic illustration and visualization of the developed RS-OCT probe. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dynamic tissue phantoms and their use in assessment of a noninvasive optical plethysmography imaging device

NASA Astrophysics Data System (ADS)

Thatcher, Jeffrey E.; Plant, Kevin D.; King, Darlene R.; Block, Kenneth L.; Fan, Wensheng; DiMaio, J. Michael

2014-05-01

Non-contact photoplethysmography (PPG) has been studied as a method to provide low-cost and non-invasive medical imaging for a variety of near-surface pathologies and two dimensional blood oxygenation measurements. Dynamic tissue phantoms were developed to evaluate this technology in a laboratory setting. The purpose of these phantoms was to generate a tissue model with tunable parameters including: blood vessel volume change; pulse wave frequency; and optical scattering and absorption parameters. A non-contact PPG imaging system was evaluated on this model and compared against laser Doppler imaging (LDI) and a traditional pulse oximeter. Results indicate non-contact PPG accurately identifies pulse frequency and appears to identify signals from optically dense phantoms with significantly higher detection thresholds than LDI.

Non-invasive optical estimate of tissue composition to differentiate malignant from benign breast lesions: A pilot study

NASA Astrophysics Data System (ADS)

Taroni, Paola; Paganoni, Anna Maria; Ieva, Francesca; Pifferi, Antonio; Quarto, Giovanna; Abbate, Francesca; Cassano, Enrico; Cubeddu, Rinaldo

2017-01-01

Several techniques are being investigated as a complement to screening mammography, to reduce its false-positive rate, but results are still insufficient to draw conclusions. This initial study explores time domain diffuse optical imaging as an adjunct method to classify non-invasively malignant vs benign breast lesions. We estimated differences in tissue composition (oxy- and deoxyhemoglobin, lipid, water, collagen) and absorption properties between lesion and average healthy tissue in the same breast applying a perturbative approach to optical images collected at 7 red-near infrared wavelengths (635-1060 nm) from subjects bearing breast lesions. The Discrete AdaBoost procedure, a machine-learning algorithm, was then exploited to classify lesions based on optically derived information (either tissue composition or absorption) and risk factors obtained from patient’s anamnesis (age, body mass index, familiarity, parity, use of oral contraceptives, and use of Tamoxifen). Collagen content, in particular, turned out to be the most important parameter for discrimination. Based on the initial results of this study the proposed method deserves further investigation.

Non-invasive diagnostic methods in dentistry

NASA Astrophysics Data System (ADS)

Todea, Carmen

2016-03-01

The paper, will present the most important non-invasive methods for diagnostic, in different fields of dentistry. Moreover, the laser-based methods will be emphasis. In orthodontics, 3D laser scanners are increasingly being used to establish database for normative population and cross-sectional growth changes but also to asses clinical outcomes in orthognatic surgical and non-surgical treatments. In prevention the main methods for diagnostic of demineralization and caries detection in early stages are represented by laser fluorescence - Quantitative Light Florescence (QLF); DiagnoDent-system-655nm; FOTI-Fiberoptic transillumination; DIFOTI-Digital Imaging Fiberoptic transillumination; and Optical Coherence Tomography (OCT). In odontology, Laser Doppler Flowmetry (LDF) is a noninvasive real time method used for determining the tooth vitality by monitoring the pulp microcirculation in traumatized teeth, fractured teeth, and teeth undergoing different conservative treatments. In periodontology, recently study shows the ability of LDF to evaluate the health of gingival tissue in periodontal tissue diseases but also after different periodontal treatments.

Non-invasive tissue temperature measurements based on quantitative diffuse optical spectroscopy (DOS) of water.

PubMed

Chung, S H; Cerussi, A E; Merritt, S I; Ruth, J; Tromberg, B J

2010-07-07

We describe the development of a non-invasive method for quantitative tissue temperature measurements using Broadband diffuse optical spectroscopy (DOS). Our approach is based on well-characterized opposing shifts in near-infrared (NIR) water absorption spectra that appear with temperature and macromolecular binding state. Unlike conventional reflectance methods, DOS is used to generate scattering-corrected tissue water absorption spectra. This allows us to separate the macromolecular bound water contribution from the thermally induced spectral shift using the temperature isosbestic point at 996 nm. The method was validated in intralipid tissue phantoms by correlating DOS with thermistor measurements (R=0.96) with a difference of 1.1+/-0.91 degrees C over a range of 28-48 degrees C. Once validated, thermal and hemodynamic (i.e. oxy- and deoxy-hemoglobin concentration) changes were measured simultaneously and continuously in human subjects (forearm) during mild cold stress. DOS-measured arm temperatures were consistent with previously reported invasive deep tissue temperature studies. These results suggest that DOS can be used for non-invasive, co-registered measurements of absolute temperature and hemoglobin parameters in thick tissues, a potentially important approach for optimizing thermal diagnostics and therapeutics.

Development of Less Toxic Treatment Strategies for Metastatic and Drug-Resistant Breast Cancer Using Noninvasive Optical Monitoring

DTIC Science & Technology

2016-09-01

AWARD NUMBER: W81XWH-15-1-0070 TITLE: Development of Less Toxic Treatment Strategies for Metastatic and Drug- Resistant Breast Cancer Using...0070 Development of Less Toxic Treatment Strategies for Metastatic and Drug- Resistant Breast Cancer Using Noninvasive Optical Monitori g 5c. PROGRAM...drug resistant breast cancer. Non-invasive Diffuse Optical Imaging technologies are able to monitor drug response and resistance through quantitative

In vivo imaging of the Mouse Model of X-Linked Juvenile Retinoschisis Using Fourier Domain Optical Coherence Tomography

PubMed Central

Xu, Jing; Molday, Laurie L.; Molday, Robert S.; Sarunic, Marinko V.

2009-01-01

Purpose The purpose of this study is to investigate Fourier Domain Optical Coherence Tomography (FD OCT) as a non-invasive tool for retinal imaging in the Rs1h knockout mouse (model for X-linked Juvenile Retinoschisis). Methods A prototype spectrometer based FD OCT system was used in combination with a custom optical beam-scanning platform. Images of the retinas from wild type and Rs1h knockout mice were acquired non-invasively using FD OCT with the specimen anesthetized. At the completion of the non-invasive FD OCT imaging, invasive retinal cross sectional images (histology) were acquired from a nearby region for comparison to the FD OCT images. Results The retinal layers could be identified in the FD OCT images, permitting delineation and thickness measurement of the outer nuclear layer (ONL). During FD OCT in vivo imaging of the Rs1h knockout mouse, holes were observed in the inner nuclear layer (INL) and retinal cell disorganization was observed as a change in the backscattering intensity profile. Comparison of the ONL measurements acquired non-invasively using FD OCT to measurements taken using histology at nearby locations showed a degeneration of roughly thirty percent of the ONL by the age of two months in Rs1h knockout mice relative to wild type. Conclusions FD OCT has been demonstrated for non-invasive imaging of retinal degeneration and observation of retinal holes in Rs1h knockout mice. PMID:19182246

Non-invasive blood glucose monitor based on spectroscopy using a smartphone.

PubMed

Dantu, Vishnu; Vempati, Jagannadh; Srivilliputhur, Srinivasan

2014-01-01

Development of a novel method for non-invasive measurement of blood glucose concentration using smartphone is discussed. Our research work has three major contributions to society and science. First, we modified and extended the Beer-Lambert's law in physics to accommodate for multiple wavelengths. This extension can aid researchers who wish to perform optical spectroscopy. Second, we successfully developed a creative and non-invasive way for diabetic patients to measure glucose levels via a smartphone. Researchers and chemists can now use their smartphones to determine the absorbance and, therefore, concentration of a chemical. Third, we created an inexpensive way to perform optical spectroscopy by using a smartphone. Monitoring blood glucose using a smartphone application that simply uses equipment already available on smartphones will improve the lives of diabetic patients who can continuously check their blood glucose levels while avoiding the current inconvenient, unhygienic, and costly invasive glucose meters.

Noninvasive monitoring of blood pressure using optical Ballistocardiography and Photoplethysmograph approaches.

PubMed

Chen, Zhihao; Yang, Xiufeng; Teo, Ju Teng; Ng, Soon Huat

2013-01-01

A new all optical method for long term and continuous blood pressure measurement and monitoring without using cuffs is proposed by using Ballistocardiography (BCG) and Photoplethysmograph (PPG). Based on BCG signal and PPG signal, a time delay between these two signals is obtained to calculate both systolic blood pressure and diastolic blood pressure via linear regression analysis. The fabricated noninvasive blood pressure monitoring device consists of a fiber sensor mat to measure BCG signal and a SpO2 sensor to measure PPG signal. A commercial digital oscillometric blood pressure meter is used to obtain reference values and for calibration. It has been found that by comparing with the reference device, our prototype has typical means and standard deviations of 9+/-5.6 mmHg for systolic blood pressure, 1.8+/-1.3 mmHg for diastolic blood pressure and 0.6+/-0.9 bpm for pulse rate, respectively. If the fiber optic SpO2 probe is used, this new all fiber cuffless noninvasive blood pressure monitoring device will truly be a MRI safe blood pressure measurement and monitoring device.

Noninvasive measurement of glucose concentration on human fingertip by optical coherence tomography

NASA Astrophysics Data System (ADS)

Chen, Tseng-Lin; Lo, Yu-Lung; Liao, Chia-Chi; Phan, Quoc-Hung

2018-04-01

A method is proposed for determining the glucose concentration on the human fingertip by extracting two optical parameters, namely the optical rotation angle and the depolarization index, using a Mueller optical coherence tomography technique and a genetic algorithm. The feasibility of the proposed method is demonstrated by measuring the optical rotation angle and depolarization index of aqueous glucose solutions with low and high scattering, respectively. It is shown that for both solutions, the optical rotation angle and depolarization index vary approximately linearly with the glucose concentration. As a result, the ability of the proposed method to obtain the glucose concentration by means of just two optical parameters is confirmed. The practical applicability of the proposed technique is demonstrated by measuring the optical rotation angle and depolarization index on the human fingertip of healthy volunteers under various glucose conditions.

Imaging pancreatobiliary ductal system with optical coherence tomography: A review

PubMed Central

Mahmud, Mohammad S; May, Gray R; Kamal, Mohammad M; Khwaja, Ahmed S; Sun, Carry; Vitkin, Alex; Yang, Victor XD

2013-01-01

An accurate, noninvasive and cost-effective method of in situ tissue evaluation during endoscopy would be highly advantageous for the detection of dysplasia or early cancer and for identifying different disease stages. Optical coherence tomography (OCT) is a noninvasive, high-resolution (1-10 μm) emerging optical imaging method with potential for identifying microscopic subsurface features in the pancreatic and biliary ductal system. Tissue microstructure of pancreaticobiliary ductal system has been successfully imaged by inserting an OCT probe through a standard endoscope operative channel. High-resolution OCT images and the technique’s endoscopic compatibility have allowed for the microstructural diagnostic of the pancreatobiliary diseases. In this review, we discussed currently available pancreaticobiliary ductal imaging systems to assess the pancreatobiliary tissue microstructure and to evaluate varieties of pancreaticobiliary disorders and diseases. Results show that OCT can improve the quality of images of pancreatobiliary system during endoscopic retrograde cholangiopancheatography procedure, which may be important in distinguishing between the neoplastic and non-neoplastic lesions. PMID:24255746

Integrated fiber optical and thermal sensor for noninvasive monitoring of blood and human tissue

NASA Astrophysics Data System (ADS)

Saetchnikov, Vladimir A.; Tcherniavskaia, Elina A.; Schiffner, Gerhard

2007-05-01

A novel concept of noninvasive monitoring of human tissue and blood based on optical diffuse reflective spectroscopy combined with metabolic heat measurements has been under development. A compact integrated fiber optical and thermal sensor has been developed. The idea of the method was to evaluate by optical spectroscopy haemoglobin and derivative concentrations and supplement with data associated with the oxidative metabolism of glucose. Body heat generated by glucose oxidation is based on the balance of capillary glucose and oxygen supply to the cells. The variation in glucose concentration is followed also by a difference from a distance (or depth) of scattered through the body radiation. So, blood glucose can be estimated by measuring the body heat and the oxygen supply. The sensor pickup contains of halogen lamp and LEDs combined with fiber optical bundle to deliver optical radiation inside and through the patient body, optical and thermal detectors. Fiber optical probe allows diffuse scattering measurement down to a depth of 2.5 mm in the skin including vascular system, which contributes to the control of the body temperature. The sensor pickup measures thermal generation, heat balance, blood flow rate, haemoglobin and derivative concentrations, environmental conditions. Multivariate statistical analysis was applied to convert various signals from the sensor pickup into physicochemical variables. By comparing the values from the noninvasive measurement with the venous plasma result, analytical functions for patient were obtained. Cluster analysis of patient groups was used to simplify a calibration procedure. Clinical testing of developed sensor is being performed.

Noninvasive Optical Monitoring of Spinal Cord Hemodynamics and Oxygenation after Acute Spinal Cord Injury

DTIC Science & Technology

2017-09-01

oxygen delivery and oxygen consumption . The oxygen portion of the Oxylite probe emits short pulses of blue LED light resulting in a fluorescent...Award Number: W81XWH-16-1-0602 TITLE: Noninvasive Optical Monitoring of Spinal Cord Hemodynamics and Oxygenation after Acute Spinal Cord Injury...COVERED 1 Sep 2016 - 31 Aug 2017 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Noninvasive Optical Monitoring of Spinal Cord Hemodynamics and Oxygenation

Optical coherence tomography for the quantitative study of cerebrovascular physiology

PubMed Central

Srinivasan, Vivek J; Atochin, Dmitriy N; Radhakrishnan, Harsha; Jiang, James Y; Ruvinskaya, Svetlana; Wu, Weicheng; Barry, Scott; Cable, Alex E; Ayata, Cenk; Huang, Paul L; Boas, David A

2011-01-01

Doppler optical coherence tomography (DOCT) and OCT angiography are novel methods to investigate cerebrovascular physiology. In the rodent cortex, DOCT flow displays features characteristic of cerebral blood flow, including conservation along nonbranching vascular segments and at branch points. Moreover, DOCT flow values correlate with hydrogen clearance flow values when both are measured simultaneously. These data validate DOCT as a noninvasive quantitative method to measure tissue perfusion over a physiologic range. PMID:21364599

A technology roadmap of smart biosensors from conventional glucose monitoring systems.

PubMed

Shende, Pravin; Sahu, Pratiksha; Gaud, Ram

2017-06-01

The objective of this review article is to focus on technology roadmap of smart biosensors from a conventional glucose monitoring system. The estimation of glucose with commercially available devices involves analysis of blood samples that are obtained by pricking finger or extracting blood from the forearm. Since pain and discomfort are associated with invasive methods, the non-invasive measurement techniques have been investigated. The non-invasive methods show advantages like non-exposure to sharp objects such as needles and syringes, due to which there is an increase in testing frequency, improved control of glucose concentration and absence of pain and biohazard materials. This review study is aimed to describe recent invasive techniques and major noninvasive techniques, viz. biosensors, optical techniques and sensor-embedded contact lenses for glucose estimation.

Feasibility of spatial frequency-domain imaging for monitoring palpable breast lesions

NASA Astrophysics Data System (ADS)

Robbins, Constance M.; Raghavan, Guruprasad; Antaki, James F.; Kainerstorfer, Jana M.

2017-12-01

In breast cancer diagnosis and therapy monitoring, there is a need for frequent, noninvasive disease progression evaluation. Breast tumors differ from healthy tissue in mechanical stiffness as well as optical properties, which allows optical methods to detect and monitor breast lesions noninvasively. Spatial frequency-domain imaging (SFDI) is a reflectance-based diffuse optical method that can yield two-dimensional images of absolute optical properties of tissue with an inexpensive and portable system, although depth penetration is limited. Since the absorption coefficient of breast tissue is relatively low and the tissue is quite flexible, there is an opportunity for compression of tissue to bring stiff, palpable breast lesions within the detection range of SFDI. Sixteen breast tissue-mimicking phantoms were fabricated containing stiffer, more highly absorbing tumor-mimicking inclusions of varying absorption contrast and depth. These phantoms were imaged with an SFDI system at five levels of compression. An increase in absorption contrast was observed with compression, and reliable detection of each inclusion was achieved when compression was sufficient to bring the inclusion center within ˜12 mm of the phantom surface. At highest compression level, contrasts achieved with this system were comparable to those measured with single source-detector near-infrared spectroscopy.

Method and apparatus for optical Doppler tomographic imaging of fluid flow velocity in highly scattering media

DOEpatents

Nelson, John Stuart; Milner, Thomas Edward; Chen, Zhongping

1999-01-01

Optical Doppler tomography permits imaging of fluid flow velocity in highly scattering media. The tomography system combines Doppler velocimetry with high spatial resolution of partially coherent optical interferometry to measure fluid flow velocity at discrete spatial locations. Noninvasive in vivo imaging of blood flow dynamics and tissue structures with high spatial resolutions of the order of 2 to 10 microns is achieved in biological systems. The backscattered interference signals derived from the interferometer may be analyzed either through power spectrum determination to obtain the position and velocity of each particle in the fluid flow sample at each pixel, or the interference spectral density may be analyzed at each frequency in the spectrum to obtain the positions and velocities of the particles in a cross-section to which the interference spectral density corresponds. The realized resolutions of optical Doppler tomography allows noninvasive in vivo imaging of both blood microcirculation and tissue structure surrounding the vessel which has significance for biomedical research and clinical applications.

Optical monitoring of spinal cord hemodynamics, a feasibility study

NASA Astrophysics Data System (ADS)

Shadgan, Babak; Kwon, Brian K.; Streijger, Femke; Manouchehri, Neda; So, Kitty; Shortt, Katelyn; Cripton, Peter A.; Macnab, Andrew

2017-02-01

Background: After an acute traumatic spinal cord injury (SCI), the spinal cord is subjected to ischemia, hypoxia, and increased hydrostatic pressure which exacerbate further secondary damage and neuronal deficit. The purpose of this pilot study was to explore the use of near infrared spectroscopy (NIRS) for non-invasive and real-time monitoring of these changes within the injured spinal cord in an animal model. NIRS is a non-invasive optical technique that utilizes light in the near infrared spectrum to monitor changes in the concentration of tissue chromophores from which alterations in tissues oxygenation and perfusion can be inferred in real time. Methods: A custom-made miniaturized NIRS sensor was developed to monitor spinal cord hemodynamics and oxygenation noninvasively and in real time simultaneously with invasive, intraparenchymal monitoring in a pig model of SCI. The spinal cord around the T10 injury site was instrumented with intraparenchymal probes inserted directly into the spinal cord to measure oxygen pressure, blood flow, and hydrostatic pressure, and the same region of the spinal cord was monitored with the custom-designed extradural NIRS probe. We investigated how well the extradural NIRS probe detected intraparenchymal changes adjacent to the injury site after alterations in systemic blood pressure, global hypoxia, and traumatic injury generated by a weight-drop contusion. Results: The NIRS sensor successfully identified periods of systemic hypoxia, re-ventilation and changes in spinal cord perfusion and oxygenation during alterations of mean arterial pressure and following spinal cord injury. Conclusion: This pilot study indicates that extradural NIRS monitoring of the spinal cord is feasible as a non-invasive optical method to identify changes in spinal cord hemodynamics and oxygenation in real time. Further development of this technique would allow clinicians to monitor real-time physiologic changes within the injured spinal cord during the acute post-injury period.

Application of optical non-invasive methods to diagnose the state of the lower limb tissues in patients with diabetes mellitus

NASA Astrophysics Data System (ADS)

Zharkikh, E. V.; Dremin, V. V.; Filina, M. A.; Makovik, I. N.; Potapova, E. V.; Zherebtsov, E. A.; Zherebtsova, A. I.; Dunaev, A. V.

2017-11-01

The paper shows the possibility of assessing the functional state of microcirculatory-tissue systems of patients with diabetes mellitus by laser Doppler flowmetry (LDF), diffuse reflectance spectroscopy (DRS) and fluorescence spectroscopy (FS) methods. A review of the existing non-invasive optical technologies used to assess the state of microcirculation and oxygen metabolism in tissues of patients with diabetes is conducted. A series of experimental studies involving 76 patients with diabetes and 46 healthy volunteers was carried out. A wavelet analysis of LDF-grams was used to evaluate the adaptive changes of microcirculation during the temperature tests. The obtained data revealed that the proposed methodology in the form of combined use of several diagnostic technologies (LDF, FS and DRS) allows us to detect the presence or absence of trophic disorders and to evaluate adaptation processes during thermal tests.

Reflectance-mode interferometric near-infrared spectroscopy quantifies brain absorption, scattering, and blood flow index in vivo.

PubMed

Borycki, Dawid; Kholiqov, Oybek; Srinivasan, Vivek J

2017-02-01

Interferometric near-infrared spectroscopy (iNIRS) is a new technique that measures time-of-flight- (TOF-) resolved autocorrelations in turbid media, enabling simultaneous estimation of optical and dynamical properties. Here, we demonstrate reflectance-mode iNIRS for noninvasive monitoring of a mouse brain in vivo. A method for more precise quantification with less static interference from superficial layers, based on separating static and dynamic components of the optical field autocorrelation, is presented. Absolute values of absorption, reduced scattering, and blood flow index (BFI) are measured, and changes in BFI and absorption are monitored during a hypercapnic challenge. Absorption changes from TOF-resolved iNIRS agree with absorption changes from continuous wave NIRS analysis, based on TOF-integrated light intensity changes, an effective path length, and the modified Beer-Lambert Law. Thus, iNIRS is a promising approach for quantitative and noninvasive monitoring of perfusion and optical properties in vivo.

Non-invasive molecular imaging for preclinical cancer therapeutic development

PubMed Central

O'Farrell, AC; Shnyder, SD; Marston, G; Coletta, PL; Gill, JH

2013-01-01

Molecular and non-invasive imaging are rapidly emerging fields in preclinical cancer drug discovery. This is driven by the need to develop more efficacious and safer treatments, the advent of molecular-targeted therapeutics, and the requirements to reduce and refine current preclinical in vivo models. Such bioimaging strategies include MRI, PET, single positron emission computed tomography, ultrasound, and optical approaches such as bioluminescence and fluorescence imaging. These molecular imaging modalities have several advantages over traditional screening methods, not least the ability to quantitatively monitor pharmacodynamic changes at the cellular and molecular level in living animals non-invasively in real time. This review aims to provide an overview of non-invasive molecular imaging techniques, highlighting the strengths, limitations and versatility of these approaches in preclinical cancer drug discovery and development. PMID:23488622

Computational fluid dynamics assisted characterization of parafoveal hemodynamics in normal and diabetic eyes using adaptive optics scanning laser ophthalmoscopy.

PubMed

Lu, Yang; Bernabeu, Miguel O; Lammer, Jan; Cai, Charles C; Jones, Martin L; Franco, Claudio A; Aiello, Lloyd Paul; Sun, Jennifer K

2016-12-01

Diabetic retinopathy (DR) is the leading cause of visual loss in working-age adults worldwide. Previous studies have found hemodynamic changes in the diabetic eyes, which precede clinically evident pathological alterations of the retinal microvasculature. There is a pressing need for new methods to allow greater understanding of these early hemodynamic changes that occur in DR. In this study, we propose a noninvasive method for the assessment of hemodynamics around the fovea (a region of the eye of paramount importance for vision). The proposed methodology combines adaptive optics scanning laser ophthalmoscopy and computational fluid dynamics modeling. We compare results obtained with this technique with in vivo measurements of blood flow based on blood cell aggregation tracking. Our results suggest that parafoveal hemodynamics, such as capillary velocity, wall shear stress, and capillary perfusion pressure can be noninvasively and reliably characterized with this method in both healthy and diabetic retinopathy patients.

Computational fluid dynamics assisted characterization of parafoveal hemodynamics in normal and diabetic eyes using adaptive optics scanning laser ophthalmoscopy

PubMed Central

Lu, Yang; Bernabeu, Miguel O.; Lammer, Jan; Cai, Charles C.; Jones, Martin L.; Franco, Claudio A.; Aiello, Lloyd Paul; Sun, Jennifer K.

2016-01-01

Diabetic retinopathy (DR) is the leading cause of visual loss in working-age adults worldwide. Previous studies have found hemodynamic changes in the diabetic eyes, which precede clinically evident pathological alterations of the retinal microvasculature. There is a pressing need for new methods to allow greater understanding of these early hemodynamic changes that occur in DR. In this study, we propose a noninvasive method for the assessment of hemodynamics around the fovea (a region of the eye of paramount importance for vision). The proposed methodology combines adaptive optics scanning laser ophthalmoscopy and computational fluid dynamics modeling. We compare results obtained with this technique with in vivo measurements of blood flow based on blood cell aggregation tracking. Our results suggest that parafoveal hemodynamics, such as capillary velocity, wall shear stress, and capillary perfusion pressure can be noninvasively and reliably characterized with this method in both healthy and diabetic retinopathy patients. PMID:28078170

Non-invasive optical detection of HBV based on serum surface-enhanced Raman spectroscopy

NASA Astrophysics Data System (ADS)

Zheng, Zuci; Wang, Qiwen; Weng, Cuncheng; Lin, Xueliang; Lin, Yao; Feng, Shangyuan

2016-10-01

An optical method of surface-enhanced Raman spectroscopy (SERS) was developed for non-invasive detection of hepatitis B surface virus (HBV). Hepatitis B virus surface antigen (HBsAg) is an established serological marker that is routinely used for the diagnosis of acute or chronic hepatitis B virus(HBV) infection. Utilizing SERS to analyze blood serum for detecting HBV has not been reported in previous literature. SERS measurements were performed on two groups of serum samples: one group for 50 HBV patients and the other group for 50 healthy volunteers. Blood serum samples are collected from healthy control subjects and patients diagnosed with HBV. Furthermore, principal components analysis (PCA) combined with linear discriminant analysis (LDA) were employed to differentiate HBV patients from healthy volunteer and achieved sensitivity of 80.0% and specificity of 74.0%. This exploratory work demonstrates that SERS serum analysis combined with PCA-LDA has tremendous potential for the non-invasive detection of HBV.

Tunable plasmonic nanobubbles for cell theranostics.

PubMed

Lukianova-Hleb, E Y; Hanna, E Y; Hafner, J H; Lapotko, D O

2010-02-26

Combining diagnostic and therapeutic processes into one (theranostics) and improving their selectivity to the cellular level may offer significant benefits in various research and disease systems and currently is not supported with efficient methods and agents. We have developed a novel method based on the gold nanoparticle-generated transient photothermal vapor nanobubbles, that we refer to as plasmonic nanobubbles (PNB). After delivery and clusterization of the gold nanoparticles (NP) to the target cells the intracellular PNBs were optically generated and controlled through the laser fluence. The PNB action was tuned in individual living cells from non-invasive high-sensitive imaging at lower fluence to disruption of the cellular membrane at higher fluence. We have achieved non-invasive 50-fold amplification of the optical scattering amplitude with the PNBs (relative to that of NPs), selective mechanical and fast damage to specific cells with bigger PNBs, and optical guidance of the damage through the damage-specific signals of the bubbles. Thus the PNBs acted as tunable theranostic agents at the cellular level and in one process that have supported diagnosis, therapy and guidance of the therapy.

Comparison of three noninvasive methods for hemoglobin screening of blood donors.

PubMed

Ardin, Sergey; Störmer, Melanie; Radojska, Stela; Oustianskaia, Larissa; Hahn, Moritz; Gathof, Birgit S

2015-02-01

To prevent phlebotomy of anemic individuals and to ensure hemoglobin (Hb) content of the blood units, Hb screening of blood donors before donation is essential. Hb values are mostly evaluated by measurement of capillary blood obtained from fingerstick. Rapid noninvasive methods have recently become available and may be preferred by donors and staff. The aim of this study was to evaluate for the first time all different noninvasive methods for Hb screening. Blood donors were screened for Hb levels in three different trials using three different noninvasive methods (Haemospect [MBR Optical Systems GmbH & Co. KG], NBM 200 [LMB Technology GmbH], Pronto-7 [Masimo Europe Ltd]) in comparison to the established fingerstick method (CompoLab Hb [Fresenius Kabi GmbH]) and to levels obtained from venous samples on a cell counter (Sysmex [Sysmex Europe GmbH]) as reference. The usability of the noninvasive methods was assessed with an especially developed survey. Technical failures occurred by using the Pronto-7 due to nail polish, skin color, or ambient light. The NBM 200 also showed a high sensitivity to ambient light and noticeably lower Hb levels for women than obtained from the Sysmex. The statistical analysis showed the following bias and standard deviation of differences of all methods in comparison to the venous results: Haemospect, -0.22 ± 1.24; NBM, 200 -0.12 ± 1.14; Pronto-7, -0.50 ± 0.99; and CompoLab Hb, -0.53 ± 0.81. Noninvasive Hb tests represent an attractive alternative by eliminating pain and reducing risks of blood contamination. The main problem for generating reliable results seems to be preanalytical variability in sampling. Despite the sensitivity to environmental stress, all methods are suitable for Hb measurement. © 2014 AABB.

Intracranial Pressure Monitoring: Invasive versus Non-Invasive Methods—A Review

PubMed Central

Raboel, P. H.; Bartek, J.; Andresen, M.; Bellander, B. M.; Romner, B.

2012-01-01

Monitoring of intracranial pressure (ICP) has been used for decades in the fields of neurosurgery and neurology. There are multiple techniques: invasive as well as noninvasive. This paper aims to provide an overview of the advantages and disadvantages of the most common and well-known methods as well as assess whether noninvasive techniques (transcranial Doppler, tympanic membrane displacement, optic nerve sheath diameter, CT scan/MRI and fundoscopy) can be used as reliable alternatives to the invasive techniques (ventriculostomy and microtransducers). Ventriculostomy is considered the gold standard in terms of accurate measurement of pressure, although microtransducers generally are just as accurate. Both invasive techniques are associated with a minor risk of complications such as hemorrhage and infection. Furthermore, zero drift is a problem with selected microtransducers. The non-invasive techniques are without the invasive methods' risk of complication, but fail to measure ICP accurately enough to be used as routine alternatives to invasive measurement. We conclude that invasive measurement is currently the only option for accurate measurement of ICP. PMID:22720148

Monte Carlo simulation of non-invasive glucose measurement based on FMCW LIDAR

NASA Astrophysics Data System (ADS)

Xiong, Bing; Wei, Wenxiong; Liu, Nan; He, Jian-Jun

2010-11-01

Continuous non-invasive glucose monitoring is a powerful tool for the treatment and management of diabetes. A glucose measurement method, with the potential advantage of miniaturizability with no moving parts, based on the frequency modulated continuous wave (FMCW) LIDAR technology is proposed and investigated. The system mainly consists of an integrated near-infrared tunable semiconductor laser and a detector, using heterodyne technology to convert the signal from time-domain to frequency-domain. To investigate the feasibility of the method, Monte Carlo simulations have been performed on tissue phantoms with optical parameters similar to those of human interstitial fluid. The simulation showed that the sensitivity of the FMCW LIDAR system to glucose concentration can reach 0.2mM. Our analysis suggests that the FMCW LIDAR technique has good potential for noninvasive blood glucose monitoring.

Assessment of post-implantation integration of engineered tissues using fluorescence lifetime spectroscopy

NASA Astrophysics Data System (ADS)

Elahi, Sakib F.; Lee, Seung Y.; Lloyd, William R.; Chen, Leng-Chun; Kuo, Shiuhyang; Zhou, Ying; Kim, Hyungjin M.; Kennedy, Robert; Marcelo, Cynthia; Feinberg, Stephen E.; Mycek, Mary-Ann

2018-02-01

Clinical translation of engineered tissue constructs requires noninvasive methods to assess construct health and viability after implantation in patients. However, current practices to monitor post-implantation construct integration are either qualitative (visual assessment) or destructive (tissue histology). As label-free fluorescence lifetime sensing can noninvasively characterize pre-implantation construct viability, we employed a handheld fluorescence lifetime spectroscopy probe to quantitatively and noninvasively assess tissue constructs that were implanted in a murine model. We designed the system to be suitable for intravital measurements: portability, localization with precise maneuverability, and rapid data acquisition. Our model tissue constructs were manufactured from primary human cells to simulate patient variability and were stressed to create a range of health states. Secreted amounts of three cytokines that relate to cellular viability were measured in vitro to assess pre-implantation construct health. In vivo optical sensing assessed tissue integration of constructs at one-week and three-weeks post-implantation. At one-week post-implantation, optical parameters correlated with in vitro pre-implantation secretion levels of all three cytokines (p < 0.05). This relationship was no longer seen at three-weeks post-implantation, suggesting comparable tissue integration independent of preimplantation health. Histology confirmed re-epithelialization of these constructs independent of pre-implantation health state, supporting the lack of a correlation. These results suggest that clinical optical diagnostic tools based on label-free fluorescence lifetime sensing of endogenous tissue fluorophores could noninvasively monitor post-implantation integration of engineered tissues.

Non-invasive glucose measurement technologies: an update from 1999 to the dawn of the new millennium.

PubMed

Khalil, Omar S

2004-10-01

There are three main issues in non-invasive (NI) glucose measurements: namely, specificity, compartmentalization of glucose values, and calibration. There has been progress in the use of near-infrared and mid-infrared spectroscopy. Recently new glucose measurement methods have been developed, exploiting the effect of glucose on erythrocyte scattering, new photoacoustic phenomenon, optical coherence tomography, thermo-optical studies on human skin, Raman spectroscopy studies, fluorescence measurements, and use of photonic crystals. In addition to optical methods, in vivo electrical impedance results have been reported. Some of these methods measure intrinsic properties of glucose; others deal with its effect on tissue or blood properties. Recent studies on skin from individuals with diabetes and its response to stimuli, skin thermo-optical response, peripheral blood flow, and red blood cell rheology in diabetes shed new light on physical and physiological changes resulting from the disease that can affect NI glucose measurements. There have been advances in understanding compartmentalization of glucose values by targeting certain regions of human tissue. Calibration of NI measurements and devices is still an open question. More studies are needed to understand the specific glucose signals and signals that are due to the effect of glucose on blood and tissue properties. These studies should be performed under normal physiological conditions and in the presence of other co-morbidities.

A noninvasive optical approach for assessing chloride extrusion activity of the K-Cl cotransporter KCC2 in neuronal cells.

PubMed

Ludwig, Anastasia; Rivera, Claudio; Uvarov, Pavel

2017-01-31

Cation-chloride cotransporters (CCCs) are indispensable for maintaining chloride homeostasis in multiple cell types, but K-Cl cotransporter KCC2 is the only CCC member with an exclusively neuronal expression in mammals. KCC2 is critical for rendering fast hyperpolarizing responses of ionotropic γ-aminobutyric acid and glycine receptors in adult neurons, for neuronal migration in the developing central nervous system, and for the formation and maintenance of small dendritic protrusions-dendritic spines. Deficit in KCC2 expression and/or activity is associated with epilepsy and neuropathic pain, and effective strategies are required to search for novel drugs augmenting KCC2 function. We revised current methods to develop a noninvasive optical approach for assessing KCC2 transport activity using a previously characterized genetically encoded chloride sensor. Our protocol directly assesses dynamics of KCC2-mediated chloride efflux and allows measuring genuine KCC2 activity with good spatial and temporal resolution. As a proof of concept, we used this approach to compare transport activities of the two known KCC2 splice isoforms, KCC2a and KCC2b, in mouse neuronal Neuro-2a cells. Our noninvasive optical protocol proved to be efficient for assessment of furosemide-sensitive chloride fluxes. Transport activities of the N-terminal splice isoforms KCC2a and KCC2b obtained by the novel approach matched to those reported previously using standard methods for measuring chloride fluxes.

Non-invasive optical monitoring of the newborn piglet brain using continuous-wave and frequency-domain spectroscopy

NASA Astrophysics Data System (ADS)

Fantini, Sergio; Hueber, Dennis; Franceschini, Maria Angela; Gratton, Enrico; Rosenfeld, Warren; Stubblefield, Phillip G.; Maulik, Dev; Stankovic, Miljan R.

1999-06-01

We have used continuous-wave (CW) and frequency-domain spectroscopy to investigate the optical properties of the newborn piglet brain in vivo and non-invasively. Three anaesthetized, intubated, ventilated and instrumented newborn piglets were placed into a stereotaxic instrument for optimal experimental stability, reproducible probe-to-scalp optical contact and 3D adjustment of the optical probe. By measuring the absolute values of the brain absorption and reduced scattering coefficients at two wavelengths (758 and 830 nm), frequency-domain spectroscopy provided absolute readings (in contrast to the relative readings of CW spectroscopy) of cerebral haemoglobin concentration and saturation during experimentally induced perturbations in cerebral haemodynamics and oxygenation. Such perturbations included a modulation of the inspired oxygen concentration, transient brain asphyxia, carotid artery occlusion and terminal brain asphyxia. The baseline cerebral haemoglobin saturation and concentration, measured with frequency-domain spectroscopy, were about 60% and 42 µM respectively. The cerebral saturation values ranged from a minimum of 17% (during transient brain asphyxia) to a maximum of 80% (during recovery from transient brain asphyxia). To analyse the CW optical data, we have (a) derived a mathematical relationship between the cerebral optical properties and the differential pathlength factor and (b) introduced a method based on the spatial dependence of the detected intensity (dc slope method). The analysis of the cerebral optical signals associated with the arterial pulse and with respiration demonstrates that motion artefacts can significantly affect the intensity recorded from a single optode pair. Motion artefacts can be strongly reduced by combining data from multiple optodes to provide relative readings in the dc slope method. We also report significant biphasic changes (initial decrease and successive increase) in the reduced scattering coefficient measured in the brain after the piglet had been sacrificed.

Comparison between invasive and noninvasive techniques of evaluation of microvascular structural alterations.

PubMed

De Ciuceis, Carolina; Agabiti Rosei, Claudia; Caletti, Stefano; Trapletti, Valentina; Coschignano, Maria A; Tiberio, Guido A M; Duse, Sarah; Docchio, Franco; Pasinetti, Simone; Zambonardi, Federica; Semeraro, Francesco; Porteri, Enzo; Solaini, Leonardo; Sansoni, Giovanna; Pileri, Paola; Rossini, Claudia; Mittempergher, Francesco; Portolani, Nazario; Ministrini, Silvia; Agabiti-Rosei, Enrico; Rizzoni, Damiano

2018-05-01

The evaluation of the morphological characteristics of small resistance arteries in humans is challenging. The gold standard method is generally considered to be the measurement by wire or pressure micromyography of the media-to-lumen ratio of subcutaneous small vessels obtained by local biopsies. However, noninvasive techniques for the evaluation of retinal arterioles were recently proposed; in particular, two approaches, scanning laser Doppler flowmetry (SLDF) and adaptive optics, seem to provide useful information; both of them provide an estimation of the wall-to-lumen ratio (WLR) of retinal arterioles. Moreover, a noninvasive measurement of basal and total capillary density may be obtained by videomicroscopy/capillaroscopy. No direct comparison of these three noninvasive techniques in the same population was previously performed; in particular, adaptive optics was never validated against micromyography. In the current study, we enrolled 41 controls and patients: 12 normotensive lean controls, 12 essential hypertensive lean patients, nine normotensive obese patients and eight hypertensive obese patients undergoing elective surgery. All patients underwent a biopsy of subcutaneous fat during surgery. Subcutaneous small resistance artery structure was assessed by wire micromyography and the media-to-lumen ratio was calculated. WLR of retinal arterioles was obtained by SLDF and adaptive optics. Functional (basal) and structural (total) microvascular density was evaluated by capillaroscopy before and after venous congestion. Our data suggest that adaptive optics has a substantial advantage over SLDF in terms of evaluation of microvascular morphology, as WLR measured with adaptive optics is more closely correlated with the M/L of subcutaneous small arteries (r = 0.84, P < 0.001 vs. r = 0.52, P < 0.05, slopes of the relations: P < 0.01 adaptive optics vs. SLDF). In addition, the reproducibility of the evaluation of the WLR with adaptive optics is far better, as compared with SLDF, as intraobserver and interobserver variation coefficients are clearly smaller. This may be important in terms of clinical evaluation of microvascular morphology in a clinical setting, as micromyography has substantial limitations in its clinical application due to the local invasiveness of the procedure.

Optogenetic pacing in Drosophila melanogaster (Conference Presentation)

NASA Astrophysics Data System (ADS)

Alex, Aneesh; Li, Airong; Men, Jing; Jerwick, Jason; Tanzi, Rudolph E.; Zhou, Chao

2016-03-01

A non-invasive, contact-less cardiac pacing technology can be a powerful tool in basic cardiac research and in clinics. Currently, electrical pacing is the gold standard for cardiac pacing. Although highly effective in controlling the cardiac function, the invasive nature, non-specificity to cardiac tissues and possible tissue damage limits its capabilities. Optical pacing of heart is a promising alternative, which is non-invasive and more specific, has high spatial and temporal precision, and avoids shortcomings in electrical stimulation. Optical coherence tomography has been proved to be an effective technique in non-invasive imaging in vivo with ultrahigh resolution and imaging speed. In the last several years, non-invasive specific optical pacing in animal hearts has been reported in quail, zebrafish, and rabbit models. However， Drosophila Melanogaster, which is a significant model with orthologs of 75% of human disease genes, has rarely been studied concerning their optical pacing in heart. Here, we combined optogenetic control of Drosophila heartbeat with optical coherence microscopy (OCM) technique for the first time. The light-gated cation channel, channelrhodopsin-2 (ChR2) was specifically expressed by transgene as a pacemaker in drosophila heart. By stimulating the pacemaker with 472 nm pulsed laser light at different frequencies, we achieved non-invasive and more specific optical control of the Drosophila heart rhythm, which demonstrates the wide potential of optical pacing for studying cardiac dynamics and development. Imaging capability of our customized OCM system was also involved to observe the pacing effect visually. No tissue damage was found after long exposure to laser pulses, which proved the safety of optogenetic control of Drosophila heart.

Optical coherence tomography in dermatology

NASA Astrophysics Data System (ADS)

Sattler, Elke; Kästle, Raphaela; Welzel, Julia

2013-06-01

Optical coherence tomography (OCT) is a noninvasive diagnostic method that offers a view into the superficial layers of the skin in vivo in real-time. An infrared broadband light source allows the investigation of skin architecture and changes up to a depth of 1 to 2 mm with a resolution between 15 and 3 μm, depending on the system used. Thus OCT enables evaluation of skin lesions, especially nonmelanoma skin cancers and inflammatory diseases, quantification of skin changes, visualization of parasitic infestations, and examination of other indications such as the investigation of nails. OCT provides a quick and useful diagnostic imaging technique for a number of clinical questions and is a valuable addition or complement to other noninvasive imaging tools such as dermoscopy, high-frequency ultrasound, and confocal laser scan microscopy.

Microemulsion characterization by the use of a noninvasive backscatter fiber optic probe

NASA Technical Reports Server (NTRS)

Ansari, Rafat R.; Dhadwal, Harbans S.; Cheung, H. M.; Meyer, William V.

1993-01-01

This paper demonstrates the utility of a noninvasive backscatter fiber optic probe for dynamic light-scattering characterization of a microemulsion comprising sodium dodecyl sulfate/1-butanol/ brine/heptane. The fiber probe, comprising two optical fibers precisely positioned in a stainless steel body, is a miniaturized and efficient self-beating dynamic light-scattering system. Accuracy of particle size estimation is better than +/- 2 percent.

Depth-sensitive optical spectroscopy for noninvasive diagnosis of oral neoplasia

NASA Astrophysics Data System (ADS)

Schwarz, Richard Alan

Oral cancer is the 11th most common cancer in the world. Cancers of the oral cavity and oropharynx account for more than 7,500 deaths each year in the United States alone. Major advances have been made in the management of oral cancer through the combined use of surgery, radiotherapy and chemotherapy, improving the quality of life for many patients; however, these advances have not led to a significant increase in survival rates, primarily because diagnosis often occurs at a late stage when treatment is more difficult and less successful. Accurate, objective, noninvasive methods for early diagnosis of oral neoplasia are needed. Here a method is presented to noninvasively evaluate oral lesions using depth-sensitive optical spectroscopy (DSOS). A ball lens coupled fiber-optic probe was developed to enable preferential targeting of different depth regions in the oral mucosa. Clinical studies of the diagnostic performance of DSOS in 157 subjects were carried out in collaboration with the University of Texas M. D. Anderson Cancer Center. An overall sensitivity of 90% and specificity of 89% were obtained for nonkeratinized oral tissue relative to histopathology. Based on these results a compact, portable version of the clinical DSOS device with real-time automated diagnostic capability was developed. The portable device was tested in 47 subjects and a sensitivity of 82% and specificity of 83% were obtained for nonkeratinized oral tissue. The diagnostic potential of multimodal platforms incorporating DSOS was explored through two pilot studies. A pilot study of DSOS in combination with widefield imaging was carried out in 29 oral cancer patients, resulting in a combined sensitivity of 94% and specificity of 69%. Widefield imaging and spectroscopy performed slightly better in combination than each method performed independently. A pilot study of DSOS in combination with the optical contrast agents 2-NBDG, EGF-Alexa 647, and proflavine was carried out in resected tissue specimens from 15 oral cancer patients. Improved contrast between neoplastic and healthy tissue was observed using 2-NBDG and EGF-Alexa 647.

Laser optical method of visualizing cutaneous blood vessels and its applications in biometry and photomedicine

NASA Astrophysics Data System (ADS)

Asimov, M. M.; Asimov, R. M.; Rubinov, A. N.

2011-05-01

We propose and examine a new approach to visualizing a local network of cutaneous blood vessels using laser optical methods for applications in biometry and photomedicine. Various optical schemes of the formation of biometrical information on the architecture of blood vessels of skin tissue are analyzed. We developed an optical model of the interaction of the laser radiation with the biological tissue and a mathematical algorithm of processing of measurement results. We show that, in medicine, the visualization of blood vessels makes it possible to calculate and determine regions of disturbance of blood microcirculation and to control tissue hypoxia, as well as to maintain the local concentration of oxygen at a level necessary for the normal cellular metabolism. We propose noninvasive optical methods for modern photomedicine and biometry for diagnostics and elimination of tissue hypoxia and for personality identification and verification via the pattern of cutaneous blood vessels.

Evaluation of metal-polymeric fixed partial prosthesis using optical coherence tomography

NASA Astrophysics Data System (ADS)

Sinescu, C.; Negrutiu, M. L.; Duma, V. F.; Marcauteanu, C.; Topala, F. I.; Rominu, M.; Bradu, A.; Podoleanu, A. Gh.

2013-11-01

Metal-Polymeric fixed partial prosthesis is the usual prosthetic treatment for many dental patients. However, during the mastication the polymeric component of the prosthesis is fractured and will be lost. This fracture is caused by the material defects or by the fracture lines trapped inside the esthetic components of the prosthesis. This will finally lead to the failure of the prosthetic treatment. Nowadays, there is no method of identification and forecast for the materials defects of the polymeric materials. The aim of this paper is to demonstrate the capability of Optical Coherence Tomography (OCT) as a non-invasive clinical method that can be used for the evaluation of metal-polymeric fixed partial prostheses. Twenty metal-polymeric fixed partial prostheses were used for this study. The esthetic component of the prostheses has been Adoro (Ivoclar). Optical investigations of the metal prostheses have revealed no material defects or fracture lines. All the prostheses were temporary cemented in the oral cavities of the patients for six month. The non-invasive method used for the investigations was OCT working in Time Domain mode at 1300 nm. The evaluations of the prostheses were performed before and after their cementation in the patient mouths. All the imagistic results were performed in 2D and than in 3D, after the reconstruction. The results obtained after the OCT evaluation allowed for the identification of 4 metal-polymeric fixed partial prostheses with material defects immediately after finishing the technological procedures. After 6 month in the oral environment other 3 fixed partial prostheses revealed fracture lines. In conclusion, OCT proved to be a valuable tool for the noninvasive evaluation of the metal-polymeric fixed partial prostheses.

Noninvasive assessment of hemodynamic and brain metabolism parameters following closed head injury in a mouse model by comparative diffuse optical reflectance approaches.

PubMed

Abookasis, David; Volkov, Boris; Shochat, Ariel; Kofman, Itamar

2016-04-01

Optical techniques have gained substantial interest over the past four decades for biomedical imaging due to their unique advantages, which may suggest their use as alternatives to conventional methodologies. Several optical techniques have been successfully adapted to clinical practice and biomedical research to monitor tissue structure and function in both humans and animal models. This paper reviews the analysis of the optical properties of brain tissue in the wavelength range between 500 and 1000 nm by three different diffuse optical reflectance methods: spatially modulated illumination, orthogonal diffuse light spectroscopy, and dual-wavelength laser speckle imaging, to monitor changes in brain tissue morphology, chromophore content, and metabolism following head injury. After induction of closed head injury upon anesthetized mice by weight-drop method, significant changes in hemoglobin oxygen saturation, blood flow, and metabolism were readily detectible by all three optical setups, up to 1 h post-trauma. Furthermore, the experimental results clearly demonstrate the feasibility and reliability of the three methodologies, and the differences between the system performances and capabilities are also discussed. The long-term goal of this line of study is to combine these optical systems to study brain pathophysiology in high spatiotemporal resolution using additional models of brain trauma. Such combined use of complementary algorithms should fill the gaps in each system's capabilities, toward the development of a noninvasive, quantitative tool to expand our knowledge of the principles underlying brain function following trauma, and to monitor the efficacy of therapeutic interventions in the clinic.

Noninvasive assessment of hemodynamic and brain metabolism parameters following closed head injury in a mouse model by comparative diffuse optical reflectance approaches

PubMed Central

Abookasis, David; Volkov, Boris; Shochat, Ariel; Kofman, Itamar

2016-01-01

Abstract. Optical techniques have gained substantial interest over the past four decades for biomedical imaging due to their unique advantages, which may suggest their use as alternatives to conventional methodologies. Several optical techniques have been successfully adapted to clinical practice and biomedical research to monitor tissue structure and function in both humans and animal models. This paper reviews the analysis of the optical properties of brain tissue in the wavelength range between 500 and 1000 nm by three different diffuse optical reflectance methods: spatially modulated illumination, orthogonal diffuse light spectroscopy, and dual-wavelength laser speckle imaging, to monitor changes in brain tissue morphology, chromophore content, and metabolism following head injury. After induction of closed head injury upon anesthetized mice by weight-drop method, significant changes in hemoglobin oxygen saturation, blood flow, and metabolism were readily detectible by all three optical setups, up to 1 h post-trauma. Furthermore, the experimental results clearly demonstrate the feasibility and reliability of the three methodologies, and the differences between the system performances and capabilities are also discussed. The long-term goal of this line of study is to combine these optical systems to study brain pathophysiology in high spatiotemporal resolution using additional models of brain trauma. Such combined use of complementary algorithms should fill the gaps in each system’s capabilities, toward the development of a noninvasive, quantitative tool to expand our knowledge of the principles underlying brain function following trauma, and to monitor the efficacy of therapeutic interventions in the clinic. PMID:27175372

Non-invasive monitoring of muscle blood perfusion by photoplethysmography: evaluation of a new application.

PubMed

Sandberg, M; Zhang, Q; Styf, J; Gerdle, B; Lindberg, L-G

2005-04-01

To evaluate a specially developed photoplethysmographic (PPG) technique, using green and near-infrared light sources, for simultaneous non-invasive monitoring of skin and muscle perfusion. Evaluation was based on assessments of changes in blood perfusion to various provocations, such as post-exercise hyperaemia and hyperaemia following the application of liniment. The deep penetrating feature of PPG was investigated by measurement of optical radiation inside the muscle. Simultaneous measurements using ultrasound Doppler and the new PPG application were performed to elucidate differences between the two methods. Specific problems related to the influence of skin temperature on blood flow were highlightened, as well. Following static and dynamic contractions an immediate increase in muscle perfusion was shown, without increase in skin perfusion. Liniment application to the skin induced a rapid increase in skin perfusion, but not in muscle. Both similarities and differences in blood flow measured by Ultrasound Doppler and PPG were demonstrated. The radiant power measured inside the muscle, by use of an optical fibre, showed that the near-infrared light penetrates down to the vascular depth inside the muscle. The results of this study indicate the potentiality of the method for non-invasive measurement of local muscle perfusion, although some considerations still have to be accounted for, such as influence of temperature on blood perfusion.

Non-invasive absolute measurement of leaf water content using terahertz quantum cascade lasers.

PubMed

Baldacci, Lorenzo; Pagano, Mario; Masini, Luca; Toncelli, Alessandra; Carelli, Giorgio; Storchi, Paolo; Tredicucci, Alessandro

2017-01-01

Plant water resource management is one of the main future challenges to fight recent climatic changes. The knowledge of the plant water content could be indispensable for water saving strategies. Terahertz spectroscopic techniques are particularly promising as a non-invasive tool for measuring leaf water content, thanks to the high predominance of the water contribution to the total leaf absorption. Terahertz quantum cascade lasers (THz QCL) are one of the most successful sources of THz radiation. Here we present a new method which improves the precision of THz techniques by combining a transmission measurement performed using a THz QCL source, with simple pictures of leaves taken by an optical camera. As a proof of principle, we performed transmission measurements on six plants of Vitis vinifera L. (cv "Colorino"). We found a linear law which relates the leaf water mass to the product between the leaf optical depth in the THz and the projected area. Results are in optimal agreement with the proposed law, which reproduces the experimental data with 95% accuracy. This method may overcome the issues related to intra-variety heterogeneities and retrieve the leaf water mass in a fast, simple, and non-invasive way. In the future this technique could highlight different behaviours in preserving the water status during drought stress.

Noninvasive imaging of cationic lipid-mediated delivery of optical and PET reporter genes in living mice.

PubMed

Iyer, Meera; Berenji, Manijeh; Templeton, Nancy S; Gambhir, Sanjiv S

2002-10-01

Gene therapy involves the safe and effective delivery of one or more genes of interest to target cells in vivo. The advantages of using nonviral delivery systems include ease of preparation, low toxicity, and weak immunogenicity. Nonviral delivery methods, when combined with a noninvasive, clinically applicable imaging assay, will greatly aid in the optimization of gene therapy approaches for cancer. We demonstrate cationic lipid-mediated noninvasive monitoring of reporter gene expression of firefly (Photinus pyralis) luciferase (fl) and a mutant herpes simplex virus type I thymidine kinase (HSV1-sr39tk, tk) in living mice using a cooled charge coupled device (CCD) camera and positron emission tomography (PET), respectively. We observe a high level of fl and tk reporter gene expression predominantly in the lungs after a single injection of the extruded DOTAP:cholesterol DNA liposome complexes by way of the tail vein, seen to be time- and dose-dependent. We observe a good correlation between the in vivo bioluminescent signal and the ex vivo firefly luciferase enzyme (FL) activity in different organs. We further demonstrate the feasibility of noninvasively imaging both optical and PET reporter gene expression in the same animal using the CCD camera and microPET, respectively.

Caries Detection Methods Based on Changes in Optical Properties between Healthy and Carious Tissue

PubMed Central

Karlsson, Lena

2010-01-01

A conservative, noninvasive or minimally invasive approach to clinical management of dental caries requires diagnostic techniques capable of detecting and quantifying lesions at an early stage, when progression can be arrested or reversed. Objective evidence of initiation of the disease can be detected in the form of distinct changes in the optical properties of the affected tooth structure. Caries detection methods based on changes in a specific optical property are collectively referred to as optically based methods. This paper presents a simple overview of the feasibility of three such technologies for quantitative or semiquantitative assessment of caries lesions. Two of the techniques are well-established: quantitative light-induced fluorescence, which is used primarily in caries research, and laser-induced fluorescence, a commercially available method used in clinical dental practice. The third technique, based on near-infrared transillumination of dental enamel is in the developmental stages. PMID:20454579

Assessment of edema volume in skin upon injury in a mouse ear model with optical coherence tomography

PubMed Central

Qin, Wan

2017-01-01

Accurate measurement of edema volume is essential for the investigation of tissue response and recovery following a traumatic injury. The measurements must be noninvasive and repetitive over time so as to monitor tissue response throughout the healing process. Such techniques are particularly necessary for the evaluation of therapeutics that are currently in development to suppress or prevent edema formation. In this study, we propose to use optical coherence tomography (OCT) technique to image and quantify edema in a mouse ear model where the injury is induced by a superficial-thickness burn. Extraction of edema volume is achieved by an attenuation compensation algorithm performed on the three-dimensional OCT images, followed by two segmentation procedures. In addition to edema volume, the segmentation method also enables accurate thickness mapping of edematous tissue, which is an important characteristic of the external symptoms of edema. To the best of our knowledge, this is the first method for noninvasively measuring absolute edema volume. PMID:27282161

Optical coherence tomography and confocal microscopy investigations of dental prostheses

NASA Astrophysics Data System (ADS)

Negrutiu, Meda L.; Sinescu, Cosmin; Hughes, Michael; Bradu, Adrian; Rominu, Mihai; Todea, Carmen; Dobre, George; Podoleanu, Adrian

2008-09-01

Dental prostheses are very complex systems, heterogenous in structure, made up from various materials, with different physical properties. An essential question mark is on the physical, chemical and mechanical compatibility between these materials. They have to satisfy high stress requirements as well as esthetic challenges. The masticatory stress may induce fractures of the prostheses, which may be triggered by initial materials defects or by alterations of the technological process. The failures of dental prostheses lead to functional, esthetic and phonetic disturbances which finally render the prosthetic treatment inefficient. The purpose of this study is to evaluate the capability of en-face optical coherence tomography as a possible non-invasive high resolution method in supplying the necessary information on the material defects of dental prostheses and microleakage at prosthetic interfaces. C-scan and B-scan OCT images as well as confocal images are acquired from a large range of samples. Gaps between the dental interfaces and material defects are clearly exposed. We conclude that OCT can successfully be used as a noninvasive analysis method.

Reflectance-mode interferometric near-infrared spectroscopy quantifies brain absorption, scattering, and blood flow index in vivo

PubMed Central

Borycki, Dawid; Kholiqov, Oybek; Srinivasan, Vivek J.

2017-01-01

Interferometric near-infrared spectroscopy (iNIRS) is a new technique that measures time-of-flight- (TOF-) resolved autocorrelations in turbid media, enabling simultaneous estimation of optical and dynamical properties. Here, we demonstrate reflectance-mode iNIRS for noninvasive monitoring of a mouse brain in vivo. A method for more precise quantification with less static interference from superficial layers, based on separating static and dynamic components of the optical field autocorrelation, is presented. Absolute values of absorption, reduced scattering, and blood flow index (BFI) are measured, and changes in BFI and absorption are monitored during a hypercapnic challenge. Absorption changes from TOF-resolved iNIRS agree with absorption changes from continuous wave NIRS analysis, based on TOF-integrated light intensity changes, an effective path length, and the modified Beer–Lambert Law. Thus, iNIRS is a promising approach for quantitative and non-invasive monitoring of perfusion and optical properties in vivo. PMID:28146535

Microtopographic characterization of pre-colonial Brazilian archaeological ceramics

NASA Astrophysics Data System (ADS)

Costa, Manuel F. M.; Magalhaes, Wagner; Alves, Márcia A.

2015-06-01

Optics and optics and photonics based inspection tools and methods had expensively proven their invaluable importance in the preservation of cultural heritage and artwork. The non-invasive inspection of the 3D shape of objects and of the micro-relief structure of its surfaces can be of high importance in the characterization process required in most works of restoration or preservation of archeological artwork. In this communication we will report on the non-invasive optical microtopographic characterization of the surface of pre-colonial ceramics and pottery of hunter-recollector-farmer' tribes of the Paranaiba valley in Minas Gerais, Brazil. The pottery found is decorated with incisions with different geometric distributions and levels of complexity corresponding to two periods of indigenous Indian occupations: one from a period dated at 1,095 +/- 186 years ago and another of the early nineteenth century dated between 212 +/- 19 years and 190 +/- 30 years ago seemingly corresponding to the occupation of the territory by southern Kayapós tribes.

Preliminary clinical investigations of a new noninvasive venous pulse oximeter

NASA Astrophysics Data System (ADS)

Chan, Daniel; Smith, Peter R.; Caine, Michael P.; Spyt, Tomasz; Boehm, Maria; Machin, David

2003-10-01

For decades, the monitoring of mixed venous oxygen saturation, SvO2 has been performed invasively using fibre-optic catheters. This procedure is not without risk as complications may arise from catheterisation. The group has devised a new non-invasive venous oximetry method which involves inducing regular modulations of the venous blood volume and associated measurement of those modulations using optical means. A clinical investigation was conducted in Glenfield Hospital, UK to evaluate the sensitivity of the new technique to haemodynamic changes such as Cardiac Output (CO) in intraoperative and postoperative cardiac patients. Preliminary trials on patients recovering from cardiac surgery yielded an average correlation of r = 0.72 between CO at different Intra Aortic Balloon Pump (IABP) augmentation levels and SvO2 measured by the new venous oximeter. In intraoperative patients undergoing off-pump cardiac surgery, SvO2 recorded by the new technique responded to unplanned events such as a cardiac arrest. CONCLUSION: The new venous oximetry technique is a promising technique which responds to haemodynamic changes such as CO and with further development might offer an alternative means of monitoring SvO2 non-invasively.

Differential phase optical coherence probe for depth-resolved detection of photothermal response in tissue.

PubMed

Telenkov, Sergey A; Dave, Digant P; Sethuraman, Shriram; Akkin, Taner; Milner, Thomas E

2004-01-07

We describe a differential phase low-coherence interferometric probe for non-invasive, quantitative imaging of photothermal phenomena in biological materials. Our detection method utilizes principles of optical coherence tomography with differential phase measurement of interference fringe signals. A dual-channel optical low-coherence probe is used to analyse laser-induced thermoelastic and thermorefractive effects in tissue with micrometre axial resolution and nanometre sensitivity. We demonstrate an application of the technique using tissue phantoms and ex-vivo tissue specimens of rodent dorsal skin.

LASERS IN MEDICINE: Laser diagnostics of biofractals

NASA Astrophysics Data System (ADS)

Ushenko, A. G.

1999-12-01

An optical approach to the problem of modelling and diagnostics of the structures of biofractal formations was considered in relation to human bone tissue. A model was proposed for the optical properties of this tissue, including three levels of fractal organisation: microcrystalline, macrocrystalline, and architectural. The studies were based on laser coherent polarimetry ensuring the retrieval of the fullest information about the optical and polarisation properties of bone tissue. A method was developed for contactless noninvasive diagnostics of the orientational and mineralogical structure of bone tissue considered as a biofractal.

Non-invasive optical modulation of local vascular permeability

NASA Astrophysics Data System (ADS)

Choi, Myunghwan; Choi, Chulhee

2011-03-01

For a systemically administered drug to act, it first needs to cross the vascular wall. This step represents a bottleneck for drug development, especially in the brain or retina, where tight junctions between endothelial cells form physiological barriers. Here, we demonstrate that femtosecond pulsed laser irradiation focused on the blood vessel wall induces transient permeabilization of plasma. Nonlinear absorption of the pulsed laser enabled the noninvasive modulation of vascular permeability with high spatial selectivity in three dimensions. By combining this method with systemic injection, we could locally deliver molecular probes in various tissues, such as brain cortex, meninges, ear, striated muscle, and bone. We suggest this method as a novel delivery tool for molecular probes or drugs.

An integrated optical coherence microscopy imaging and optical stimulation system for optogenetic pacing in Drosophila melanogaster (Conference Presentation)

NASA Astrophysics Data System (ADS)

Alex, Aneesh; Li, Airong; Men, Jing; Jerwick, Jason; Tanzi, Rudolph E.; Zhou, Chao

2016-03-01

Electrical stimulation is the clinical standard for cardiac pacing. Although highly effective in controlling cardiac rhythm, the invasive nature, non-specificity to cardiac tissues and possible tissue damage limits its applications. Optogenetic pacing of the heart is a promising alternative, which is non-invasive and more specific, has high spatial and temporal precision, and avoids the shortcomings in electrical stimulation. Drosophila melanogaster, which is a powerful model organism with orthologs of nearly 75% of human disease genes, has not been studied for optogenetic pacing in the heart. Here, we developed a non-invasive integrated optical pacing and optical coherence microscopy (OCM) imaging system to control the heart rhythm of Drosophila at different developmental stages using light. The OCM system is capable of providing high imaging speed (130 frames/s) and ultrahigh imaging resolutions (1.5 μm and 3.9 μm for axial and transverse resolutions, respectively). A light-sensitive pacemaker was developed in Drosophila by specifically expressing the light-gated cation channel, channelrhodopsin-2 (ChR2) in transgenic Drosophila heart. We achieved non-invasive and specific optical control of the Drosophila heart rhythm throughout the fly's life cycle (larva, pupa, and adult) by stimulating the heart with 475 nm pulsed laser light. Heart response to stimulation pulses was monitored non-invasively with OCM. This integrated non-invasive optogenetic control and in vivo imaging technique provides a novel platform for performing research studies in developmental cardiology.

Decalcification using ethylenediaminetetraacetic acid for clear microstructure imaging of cochlea through optical coherence tomography

NASA Astrophysics Data System (ADS)

Lee, Jaeyul; Kim, Kanghae; Wijesinghe, Ruchire Eranga; Jeon, Doekmin; Lee, Sang Heun; Jeon, Mansik; Jang, Jeong Hun

2016-08-01

The aim of this study was to analyze the effectiveness of decalcification using ethylenediaminetetraacetic acid (EDTA) as an optical clearing method to enhance the depth visibility of internal soft tissues of cochlea. Ex vivo mouse and guinea pig cochlea samples were soaked in EDTA solutions for decalcification, and swept source optical coherence tomography (OCT) was used as imaging modality to monitor the decalcified samples consecutively. The monitored noninvasive cross-sectional images showed that the mouse and guinea pig cochlea samples had to be decalcified for subsequent 7 and 14 days, respectively, to obtain the optimal optical clearing results. Using this method, difficulties in imaging of internal cochlea microstructures of mice could be evaded. The obtained results verified that the depth visibility of the decalcified ex vivo samples was enhanced.

Development, history, and future of automated cell counters.

PubMed

Green, Ralph; Wachsmann-Hogiu, Sebastian

2015-03-01

Modern automated hematology instruments use either optical methods (light scatter), impedance-based methods based on the Coulter principle (changes in electrical current induced by blood cells flowing through an electrically charged opening), or a combination of both optical and impedance-based methods. Progressive improvement in these instruments has allowed the enumeration and evaluation of blood cells with great accuracy, precision, and speed at very low cost. Future directions of hematology instrumentation include the addition of new parameters and the development of point-of-care instrumentation. In the future, in-vivo analysis of blood cells may allow noninvasive and near-continuous measurements. Copyright © 2015 Elsevier Inc. All rights reserved.

Isis: Integrated Shape Imaging System (Oxford Metrics Ltd.) A New System For Follow-Up Of Scoliosis.

NASA Astrophysics Data System (ADS)

Van Poucke, M.; Boone, P.; Vercauteren, M.

1986-07-01

ISIS is a non-invasive optical method for obtaining topographical data of the human back shape. It is used for the follow-up of scoliosis (spinal deformity). Using the ISIS, the number of x-ray photographs can be reduced in the scoliosis clinics.

Optical sensor technology for a noninvasive medical blood diagnosis

NASA Astrophysics Data System (ADS)

Kraitl, Jens; Ewald, Hartmut; Gehring, Hartmut

2007-02-01

NIR-spectroscopy and Photoplethysmography (PPG) and is used for a measurement of blood components. The fact that the absorption-coefficients μ a and scattering-coefficients μ s for blood differ at difference wavelengths has been exploited and is used for calculation of the optical absorbability characteristics of human blood yielding information on blood components like hemoglobin and oxygen saturation. The measured PPG time signals and the ratio between the peak to peak pulse amplitudes are used for a measurement of these parameters. A newly developed PMD device has been introduced. The non-invasive in-vivo multi-spectral method is based on the radiation of monochromatic light, emitted by laser diodes, through an area of skin on the finger. Deferrals between the proportions of hemoglobin and plasma in the intravasal volume should be detected photo-electrically by signal-analytic evaluation of the signals. The computed nonlinear coefficients are used for the measurement and calculation of the relative hemoglobin concentration change. Results with this photometric method to measure changes in the hemoglobin concentration were demonstrated during measurements with a hemodynamic model and healthy subjects. The PMD is suitable for non-invasive continuous online monitoring of one or more biologic constituent values. The objective of this development is to reduce the dependence on measurement techniques which require that a sample of blood be withdrawn from the patient for in-vitro analysis. Any invasive method used on the patient to obtain blood is accompanied by problems of inconvenience, stress, and discomfort. The patient is also exposed to the normal risks of infection associated with such invasive methods.

Transdermal Diagnosis of Malaria Using Vapor Nanobubbles.

PubMed

Lukianova-Hleb, Ekaterina; Bezek, Sarah; Szigeti, Reka; Khodarev, Alexander; Kelley, Thomas; Hurrell, Andrew; Berba, Michail; Kumar, Nirbhay; D'Alessandro, Umberto; Lapotko, Dmitri

2015-07-01

A fast, precise, noninvasive, high-throughput, and simple approach for detecting malaria in humans and mosquitoes is not possible with current techniques that depend on blood sampling, reagents, facilities, tedious procedures, and trained personnel. We designed a device for rapid (20-second) noninvasive diagnosis of Plasmodium falciparum infection in a malaria patient without drawing blood or using any reagent. This method uses transdermal optical excitation and acoustic detection of vapor nanobubbles around intraparasite hemozoin. The same device also identified individual malaria parasite-infected Anopheles mosquitoes in a few seconds and can be realized as a low-cost universal tool for clinical and field diagnoses.

Adaptive optics optical coherence tomography at 120,000 depth scans/s for non-invasive cellular phenotyping of the living human retina

PubMed Central

Torti, Cristiano; Považay, Boris; Hofer, Bernd; Unterhuber, Angelika; Carroll, Joseph; Ahnelt, Peter Kurt; Drexler, Wolfgang

2012-01-01

This paper presents a successful combination of ultra-high speed (120,000 depth scans/s), ultra-high resolution optical coherence tomography with adaptive optics and an achromatizing lens for compensation of monochromatic and longitudinal chromatic ocular aberrations, respectively, allowing for non-invasive volumetric imaging in normal and pathologic human retinas at cellular resolution. The capability of this imaging system is demonstrated here through preliminary studies by probing cellular intraretinal structures that have not been accessible so far with in vivo, non-invasive, label-free imaging techniques, including pigment epithelial cells, micro-vasculature of the choriocapillaris, single nerve fibre bundles and collagenous plates of the lamina cribrosa in the optic nerve head. In addition, the volumetric extent of cone loss in two colour-blinds could be quantified for the first time. This novel technique provides opportunities to enhance the understanding of retinal pathogenesis and early diagnosis of retinal diseases. PMID:19997159

Detection of canine skin and subcutaneous tumors by visible and near-infrared diffuse reflectance spectroscopy

NASA Astrophysics Data System (ADS)

Cugmas, Blaž; Plavec, Tanja; Bregar, Maksimilijan; Naglič, Peter; Pernuš, Franjo; Likar, Boštjan; Bürmen, Miran

2015-03-01

Cancer is the main cause of canine morbidity and mortality. The existing evaluation of tumors requires an experienced veterinarian and usually includes invasive procedures (e.g., fine-needle aspiration) that can be unpleasant for the dog and the owner. We investigate visible and near-infrared diffuse reflectance spectroscopy (DRS) as a noninvasive optical technique for evaluation and detection of canine skin and subcutaneous tumors ex vivo and in vivo. The optical properties of tumors and skin were calculated in a spectrally constrained manner, using a lookup table-based inverse model. The obtained optical properties were analyzed and compared among different tumor groups. The calculated parameters of the absorption and reduced scattering coefficients were subsequently used for detection of malignant skin and subcutaneous tumors. The detection sensitivity and specificity of malignant tumors ex vivo were 90.0% and 73.5%, respectively, while corresponding detection sensitivity and specificity of malignant tumors in vivo were 88.4% and 54.6%, respectively. The obtained results show that the DRS is a promising noninvasive optical technique for detection and classification of malignant and benign canine skin and subcutaneous tumors. The method should be further investigated on tumors with common origin.

Polarization sensitive optical low-coherence reflectometry for blood glucose monitoring in human subjects

NASA Astrophysics Data System (ADS)

Solanki, Jitendra; Choudhary, Om Prakash; Sen, P.; Andrews, J. T.

2013-07-01

A device based on polarization sensitive optical low-coherence reflectometry is developed to monitor blood glucose levels in human subjects. The device was initially tested with tissue phantom. The measurements with human subjects for various glucose concentration levels are found to be linearly dependent on the ellipticity obtainable from the home-made phase-sensitive optical low-coherence reflectometry device. The linearity obtained between glucose concentration and ellipticity are explained with theoretical calculations using Mie theory. A comparison of results with standard clinical methods establishes the utility of the present device for non-invasive glucose monitoring.

Noninvasive determination of optical lever sensitivity in atomic force microscopy

NASA Astrophysics Data System (ADS)

Higgins, M. J.; Proksch, R.; Sader, J. E.; Polcik, M.; Mc Endoo, S.; Cleveland, J. P.; Jarvis, S. P.

2006-01-01

Atomic force microscopes typically require knowledge of the cantilever spring constant and optical lever sensitivity in order to accurately determine the force from the cantilever deflection. In this study, we investigate a technique to calibrate the optical lever sensitivity of rectangular cantilevers that does not require contact to be made with a surface. This noncontact approach utilizes the method of Sader et al. [Rev. Sci. Instrum. 70, 3967 (1999)] to calibrate the spring constant of the cantilever in combination with the equipartition theorem [J. L. Hutter and J. Bechhoefer, Rev. Sci. Instrum. 64, 1868 (1993)] to determine the optical lever sensitivity. A comparison is presented between sensitivity values obtained from conventional static mode force curves and those derived using this noncontact approach for a range of different cantilevers in air and liquid. These measurements indicate that the method offers a quick, alternative approach for the calibration of the optical lever sensitivity.

Method for quantifying optical properties of the human lens

DOEpatents

Loree, deceased, Thomas R.; Bigio, Irving J.; Zuclich, Joseph A.; Shimada, Tsutomu; Strobl, Karlheinz

1999-01-01

Method for quantifying optical properties of the human lens. The present invention includes the application of fiberoptic, OMA-based instrumentation as an in vivo diagnostic tool for the human ocular lens. Rapid, noninvasive and comprehensive assessment of the optical characteristics of a lens using very modest levels of exciting light are described. Typically, the backscatter and fluorescence spectra (from about 300- to 900-nm) elicited by each of several exciting wavelengths (from about 300- to 600-nm) are collected within a few seconds. The resulting optical signature of individual lenses is then used to assess the overall optical quality of the lens by comparing the results with a database of similar measurements obtained from a reference set of normal human lenses having various ages. Several metrics have been identified which gauge the optical quality of a given lens relative to the norm for the subject's chronological age. These metrics may also serve to document accelerated optical aging and/or as early indicators of cataract or other disease processes.

Method for quantifying optical properties of the human lens

DOEpatents

Loree, T.R.; Bigio, I.J.; Zuclich, J.A.; Shimada, Tsutomu; Strobl, K.

1999-04-13

A method is disclosed for quantifying optical properties of the human lens. The present invention includes the application of fiberoptic, OMA-based instrumentation as an in vivo diagnostic tool for the human ocular lens. Rapid, noninvasive and comprehensive assessment of the optical characteristics of a lens using very modest levels of exciting light are described. Typically, the backscatter and fluorescence spectra (from about 300- to 900-nm) elicited by each of several exciting wavelengths (from about 300- to 600-nm) are collected within a few seconds. The resulting optical signature of individual lenses is then used to assess the overall optical quality of the lens by comparing the results with a database of similar measurements obtained from a reference set of normal human lenses having various ages. Several metrics have been identified which gauge the optical quality of a given lens relative to the norm for the subject`s chronological age. These metrics may also serve to document accelerated optical aging and/or as early indicators of cataract or other disease processes. 8 figs.

Detection of DSS-induced gastrointestinal mucositis in mice by non-invasive optical near-infrared (NIR) imaging of cathepsin activity.

PubMed

Finnberg, Niklas K; Liu, Yvette; El-Deiry, Wafik S

2013-08-01

Approximately 1.4 million people of the US population suffer from Inflammatory Bowel Disease (IBD) of which the most common conditions are ulcerative colitis (UC) and Crohn disease (CD). Colonoscopy and small bowel follow through are considered the current gold standard in diagnosing IBD. However, improved imaging and increased diagnostic sensitivity could be beneficial. Optical molecular imaging has the potential to become a powerful and practical tool for early detection, image-guided biopsy, and surgery in diagnosing and treating patients with IBD. Here we used a well characterized chemical model to initiate experimental IBD in mice by feeding with dextran sulfate sodium (DSS) containing drinking water in an attempt to investigate the utility of non-invasive infrared (NIR) optical imaging in the detection gastrointestinal (GI) injury. We employed a "smart probe" (ProSense680) cleaved and fluorescently activated in the NIR-spectrum by various forms of secreted cathepsins. This probe has previously been shown to serve as a biomarker for the homing of inflammatory cells to injury. Our investigation suggests that NIR optical imaging can detect cathepsin-dependent probe cleavage non-invasively in animals with DSS-induced IBD. Increased tissue probe-retention and fluorescence was associated with increased infiltration of inflammatory cells, epithelial atrophy and sterilization of the mucosa. Furthermore, using NIR-imaging ex vivo we were able to document regional "hot spots" of inflammatory damage to the large intestine suggesting this method potentially could be coupled with colonoscopy investigation to aid in the sampling and the diagnostics of IBD.

Non-invasive dual fluorescence in vivo imaging for detection of macrophage infiltration and matrix metalloproteinase (MMP) activity in inflammatory arthritic joints

PubMed Central

Cho, Hongsik; Bhatti, Fazal-Ur-Rehman; Yoon, Tae Won; Hasty, Karen A.; Stuart, John M.; Yi, Ae-Kyung

2016-01-01

Detection and intervention at an early stage is a critical factor to impede arthritis progress. Here we present a non-invasive method to detect inflammatory changes in joints of arthritic mice. Inflammation was monitored by dual fluorescence optical imaging for near-infrared fluorescent (750F) matrix-metalloproteinase activatable agent and allophycocyanin-conjugated anti-mouse CD11b. Increased intensity of allophycocyanin (indication of macrophage accumulation) and 750F (indication of matrix-metalloproteinase activity) showed a biological relationship with the arthritis severity score and the histopathology score of arthritic joints. Our results demonstrate that this method can be used to detect early stages of arthritis with minimum intervention in small animal models. PMID:27231625

Spread spectrum time-resolved diffuse optical measurement system for enhanced sensitivity in detecting human brain activity

NASA Astrophysics Data System (ADS)

Mehta, Kalpesh; Hasnain, Ali; Zhou, Xiaowei; Luo, Jianwen; Penney, Trevor B.; Chen, Nanguang

2017-04-01

Diffuse optical spectroscopy (DOS) and imaging methods have been widely applied to noninvasive detection of brain activity. We have designed and implemented a low cost, portable, real-time one-channel time-resolved DOS system for neuroscience studies. Phantom experiments were carried out to test the performance of the system. We further conducted preliminary human experiments and demonstrated that enhanced sensitivity in detecting neural activity in the cortex could be achieved by the use of late arriving photons.

Application of light and ultrasound for medical diagnostics and treatment

NASA Astrophysics Data System (ADS)

Esenaliev, Rinat O.

2002-07-01

We develop novel optical and ultrasound techniques for medical noninvasive diagnostics and treatment. In this review, we present our results on the development of: (1) optoacoustic technique for detection of small tumors; (2) optoacoustic monitoring of blood oxygenation; (3) optoacoustic monitoring during thermotherapy; (4) optical coherence tomography for monitoring of blood glucose concentration; and (5) laser- and ultrasound-based anti- cancer drug delivery technique. Motivation, experimental methods, results obtained in vitro and in vivo with the use of these techniques are presented.

Non-invasive measurement of the temperature rise in tissue surrounding a kidney stone subjected to ultrasonic propulsion.

PubMed

Oweis, Ghanem F; Dunmire, Barbrina L; Cunitz, Bryan W; Bailey, Michael R

2015-01-01

Transcutaneous focused ultrasound (US) is used to propel kidney stones using acoustic radiation force. It is important to estimate the level of heating generated at the stone/tissue interface for safety assessment. An in-vitro experiment is conducted to measure the temperature rise in a tissue-mimicking phantom with an embedded artificial stone and subjected to a focused beam from an imaging US array. A novel optical-imaging-based thermometry method is described using an optically clear tissue phantom. Measurements are compared to the output from a fine wire thermocouple placed on the stone surface. The optical method has good sensitivity, and it does not suffer from artificial viscous heating typically observed with invasive probes and thermocouples.

A Complex Approach to Noninvasive Estimation of Microcirculatory Tissue Impairments in Feet of Patients with Diabetes Mellitus using Spectroscopy

NASA Astrophysics Data System (ADS)

Potapova, E. V.; Dremin, V. V.; Zherebtsov, E. A.; Makovik, I. N.; Zharkikh, E. V.; Dunaev, A. V.; Pilipenko, O. V.; Sidorov, V. V.; Krupatkin, A. I.

2017-12-01

The possibility of a complex approach for studying changes in the system of blood microcirculation and metabolic processes in the biotissue of lower extremities using optical noninvasive methods of laser doppler flowmetry (LDF), fluorescence spectroscopy, and diffuse reflectance spectroscopy in combination with different modes of heating tests has been assessed. Seventy-six patients with type 2 diabetes mellitus, with 14 patients having visible trophic foot impairments, and 48 healthy volunteers have been examined. The parameters of LDF signals and spectra of fluorescence intensity and diffuse reflectance for foot skin have been analyzed. Statistically significant differences in the recorded parameters between the groups under study have been found. It has been concluded that combined application of noninvasive methods of spectroscopy could be used for diagnostics of complications both upon the occurrence of preliminary symptoms of diabetes, when pathological changes are still reversible, and in the presence of impairments to prevent aggravation of the disease and select an adequate correction of the treatment.

A phantom with pulsating artificial vessels for non-invasive fetal pulse oximetry.

PubMed

Laqua, Daniel; Pollnow, Stefan; Fischer, Jan; Ley, Sebastian; Husar, Peter

2014-01-01

Arterial oxygen saturation of the fetus is an important parameter for monitoring its physical condition. During labor and delivery the transabdominal non-invasive fetal pulse oximetry could minimize the risk for mother and fetus, compared to other existing invasive examination methods. In this contribution, we developed a physical-like phantom to investigate new sensor circuits and algorithms of a non-invasive diagnostic method for fetal pulse oximetry. Hence, the developed artificial vascular system consists of two independent tube systems representing the maternal and fetal vessel system. The arterial blood pressure is reproduced with a pre-pressure and an artificial vascular system. Each pulse wave can be reproduced, by digital control of a proportional valve, adjustable viscoelastic elements, and resistances. The measurements are performed by pressure transducers, optical sensor units, and a coplanar capacitive sensor. Transmission and reflection measurements have shown that the fetal and maternal pulse waves can be reproduced qualitatively. The measured light represents the transabdominal modulated signal on an abdomen of a pregnant woman.

Non-invasive intravital imaging of cellular differentiation with a bright red-excitable fluorescent protein

PubMed Central

Chu, Jun; Haynes, Russell D; Corbel, Stéphane Y; Li, Pengpeng; González-González, Emilio; Burg, John S; Ataie, Niloufar J; Lam, Amy J; Cranfill, Paula J; Baird, Michelle A; Davidson, Michael W; Ng, Ho-Leung; Garcia, K Christopher; Contag, Christopher H; Shen, Kang; Blau, Helen M; Lin, Michael Z

2014-01-01

A method for non-invasive visualization of genetically labelled cells in animal disease models with micron-level resolution would greatly facilitate development of cell-based therapies. Imaging of fluorescent proteins (FPs) using red excitation light in the “optical window” above 600 nm is one potential method for visualizing implanted cells. However, previous efforts to engineer FPs with peak excitation beyond 600 nm have resulted in undesirable reductions in brightness. Here we report three new red-excitable monomeric FPs obtained by structure-guided mutagenesis of mNeptune, previously the brightest monomeric FP when excited beyond 600 nm. Two of these, mNeptune2 and mNeptune2.5, demonstrate improved maturation and brighter fluorescence, while the third, mCardinal, has a red-shifted excitation spectrum without reduction in brightness. We show that mCardinal can be used to non-invasively and longitudinally visualize the differentiation of myoblasts and stem cells into myocytes in living mice with high anatomical detail. PMID:24633408

A non-invasive experimental approach for surface temperature measurements on semi-crystalline thermoplastics

NASA Astrophysics Data System (ADS)

Boztepe, Sinan; Gilblas, Remi; de Almeida, Olivier; Le Maoult, Yannick; Schmidt, Fabrice

2017-10-01

Most of the thermoforming processes of thermoplastic polymers and their composites are performed adopting a combined heating and forming stages at which a precursor is heated prior to the forming. This step is done in order to improve formability by softening the thermoplastic polymer. Due to low thermal conductivity and semi-transparency of polymers, infrared (IR) heating is widely used for thermoforming of such materials. Predictive radiation heat transfer models for temperature distributions are therefore critical for optimizations of thermoforming process. One of the key challenges is to build a predictive model including the physical background of radiation heat transfer phenomenon in semi-crystalline thermoplastics as their microcrystalline structure introduces an optically heterogeneous medium. In addition, the accuracy of a predictive model is required to be validated experimentally where IR thermography is one of the suitable methods for such a validation as it provides a non-invasive, full-field surface temperature measurement. Although IR cameras provide a non-invasive measurement, a key issue for obtaining a reliable measurement depends on the optical characteristics of a heated material and the operating spectral band of IR camera. It is desired that the surface of a material to be measured has a spectral band where the material behaves opaque and an employed IR camera operates in the corresponding band. In this study, the optical characteristics of the PO-based polymer are discussed and, an experimental approach is proposed in order to measure the surface temperature of the PO-based polymer via IR thermography. The preliminary analyses showed that IR thermographic measurements may not be simply performed on PO-based polymers and require a correction method as their semi-transparent medium introduce a challenge to obtain reliable surface temperature measurements.

Non-invasive, Multimodal Functional Imaging of the Intestine with Frozen Micellar Naphthalocyanines

PubMed Central

Zhang, Yumiao; Jeon, Mansik; Rich, Laurie J.; Hong, Hao; Geng, Jumin; Zhang, Yin; Shi, Sixiang; Barnhart, Todd E.; Alexandridis, Paschalis; Huizinga, Jan D.; Seshadri, Mukund; Cai, Weibo; Kim, Chulhong; Lovell, Jonathan F.

2014-01-01

Overview There is a need for safer and improved methods for non-invasive imaging of the gastrointestinal tract. Modalities based on X-ray radiation, magnetic resonance and ultrasound suffer from limitations with respect to safety, accessibility or lack of adequate contrast. Functional intestinal imaging of dynamic gut processes has not been practical using existing approaches. Here, we report the development of a family of nanoparticles that can withstand the harsh conditions of the stomach and intestine, avoid systemic absorption, and give rise to good optical contrast for photoacoustic imaging. The hydrophobicity of naphthalocyanine dyes was exploited to generate purified ~20 nm frozen micelles, which we call nanonaps, with tunable and large near-infrared absorption values (>1000). Unlike conventional chromophores, nanonaps exhibited non-shifting spectra at ultrahigh optical densities and, following oral administration in mice, passed safely through the gastrointestinal tract. Non-invasive, non-ionizing photoacoustic techniques were used to visualize nanonap intestinal distribution with low background and remarkable resolution with 0.5 cm depth, and enabled real-time intestinal functional imaging with ultrasound co-registration. Positron emission tomography following seamless nanonap radiolabelling allowed complementary whole body imaging. PMID:24997526

Optical Microangiography Based on Optical Coherence Tomography

NASA Astrophysics Data System (ADS)

Reif, Roberto; Wang, Ruikang K.

Proper homeostasis regulation of in vivo biological systems requires microvascular blood perfusion, which is the process of delivering blood into the tissue's capillary beds. Abnormal tissue vascularization has been associated with various diseases such as cancer, diabetes, neurological disorders, wounds, and inflammation. Understanding the changes in the vascular network or microangiography will have an important role in determining the causes and developing potential treatments for these diseases. Optical coherence tomography (OCT) is a noninvasive method for imaging three-dimensional biological tissues with high resolution (~10 µm) and without requiring the use of contrast agents. In this chapter we review several techniques for using OCT to determine blood flow velocities and the vessel morphology (optical microangiography). Different techniques will be discussed with a brief explanation of their limitations. Also, methods for quantifying these images are presented, as well as the depiction of several applications.

Non-invasive timing of gas gun-launched projectiles using external surface-mounted optical fiber-Bragg grating strain gauges

NASA Astrophysics Data System (ADS)

Goodwin, Peter M.; Marshall, Bruce R.; Stevens, Gerald D.; Dattelbaum, Dana M.

2013-03-01

Non-invasive detection methods for tracking gun-launched projectiles are important not only for assessment of gun performance but are also essential for timing a variety of diagnostics, for example, to investigate plate-impact events for shock compression experiments. Measurement of the time of passage of a projectile moving inside of the gun barrel can be achieved by detection of the transient hoop strain induced in the barrel of a light-gas gun by the passage of the projectile using external, barrel surface-mounted optical fiber-Bragg grating strain gauges. Optical fiber-Bragg gratings have been implemented and their response characterized on single-stage and two-stage light gas guns routinely used for dynamic experimentation at Los Alamos National Laboratory. Two approaches, using either broadband or narrowband illumination, were used to monitor changes in the Bragg wavelength of the fiber-Bragg gratings. The second approach, using narrowband laser illumination, offered the highest sensitivity. The feasibility of using these techniques to generate early, pre-event signals useful for triggering high-latency diagnostics was demonstrated.

Non-invasive timing of gas gun-launched projectiles using external surface-mounted optical fiber-Bragg grating strain gauges.

PubMed

Goodwin, Peter M; Marshall, Bruce R; Stevens, Gerald D; Dattelbaum, Dana M

2013-03-01

Non-invasive detection methods for tracking gun-launched projectiles are important not only for assessment of gun performance but are also essential for timing a variety of diagnostics, for example, to investigate plate-impact events for shock compression experiments. Measurement of the time of passage of a projectile moving inside of the gun barrel can be achieved by detection of the transient hoop strain induced in the barrel of a light-gas gun by the passage of the projectile using external, barrel surface-mounted optical fiber-Bragg grating strain gauges. Optical fiber-Bragg gratings have been implemented and their response characterized on single-stage and two-stage light gas guns routinely used for dynamic experimentation at Los Alamos National Laboratory. Two approaches, using either broadband or narrowband illumination, were used to monitor changes in the Bragg wavelength of the fiber-Bragg gratings. The second approach, using narrowband laser illumination, offered the highest sensitivity. The feasibility of using these techniques to generate early, pre-event signals useful for triggering high-latency diagnostics was demonstrated.

Non-invasive measurement of choroidal volume change and ocular rigidity through automated segmentation of high-speed OCT imaging

PubMed Central

Beaton, L.; Mazzaferri, J.; Lalonde, F.; Hidalgo-Aguirre, M.; Descovich, D.; Lesk, M. R.; Costantino, S.

2015-01-01

We have developed a novel optical approach to determine pulsatile ocular volume changes using automated segmentation of the choroid, which, together with Dynamic Contour Tonometry (DCT) measurements of intraocular pressure (IOP), allows estimation of the ocular rigidity (OR) coefficient. Spectral Domain Optical Coherence Tomography (OCT) videos were acquired with Enhanced Depth Imaging (EDI) at 7Hz during ~50 seconds at the fundus. A novel segmentation algorithm based on graph search with an edge-probability weighting scheme was developed to measure choroidal thickness (CT) at each frame. Global ocular volume fluctuations were derived from frame-to-frame CT variations using an approximate eye model. Immediately after imaging, IOP and ocular pulse amplitude (OPA) were measured using DCT. OR was calculated from these peak pressure and volume changes. Our automated segmentation algorithm provides the first non-invasive method for determining ocular volume change due to pulsatile choroidal filling, and the estimation of the OR constant. Future applications of this method offer an important avenue to understanding the biomechanical basis of ocular pathophysiology. PMID:26137373

Structured Illumination Diffuse Optical Tomography for Mouse Brain Imaging

NASA Astrophysics Data System (ADS)

Reisman, Matthew David

As advances in functional magnetic resonance imaging (fMRI) have transformed the study of human brain function, they have also widened the divide between standard research techniques used in humans and those used in mice, where high quality images are difficult to obtain using fMRI given the small volume of the mouse brain. Optical imaging techniques have been developed to study mouse brain networks, which are highly valuable given the ability to study brain disease treatments or development in a controlled environment. A planar imaging technique known as optical intrinsic signal (OIS) imaging has been a powerful tool for capturing functional brain hemodynamics in rodents. Recent wide field-of-view implementations of OIS have provided efficient maps of functional connectivity from spontaneous brain activity in mice. However, OIS requires scalp retraction and is limited to imaging a 2-dimensional view of superficial cortical tissues. Diffuse optical tomography (DOT) is a non-invasive, volumetric neuroimaging technique that has been valuable for bedside imaging of patients in the clinic, but previous DOT systems for rodent neuroimaging have been limited by either sparse spatial sampling or by slow speed. My research has been to develop diffuse optical tomography for whole brain mouse neuroimaging by expanding previous techniques to achieve high spatial sampling using multiple camera views for detection and high speed using structured illumination sources. I have shown the feasibility of this method to perform non-invasive functional neuroimaging in mice and its capabilities of imaging the entire volume of the brain. Additionally, the system has been built with a custom, flexible framework to accommodate the expansion to imaging multiple dynamic contrasts in the brain and populations that were previously difficult or impossible to image, such as infant mice and awake mice. I have contributed to preliminary feasibility studies of these more advanced techniques using OIS, which can now be carried out using the structured illumination diffuse optical tomography technique to perform longitudinal, non-invasive studies of the whole volume of the mouse brain.

Spectroscopic methods for the photodiagnosis of nonmelanoma skin cancer.

PubMed

Drakaki, Eleni; Vergou, Theognosia; Dessinioti, Clio; Stratigos, Alexander J; Salavastru, Carmen; Antoniou, Christina

2013-06-01

The importance of dermatological noninvasive imaging techniques has increased over the last decades, aiming at diagnosing nonmelanoma skin cancer (NMSC). Technological progress has led to the development of various analytical tools, enabling the in vivo/in vitro examination of lesional human skin with the aim to increase diagnostic accuracy and decrease morbidity and mortality. The structure of the skin layers, their chemical composition, and the distribution of their compounds permits the noninvasive photodiagnosis of skin diseases, such as skin cancers, especially for early stages of malignant tumors. An important role in the dermatological diagnosis and disease monitoring has been shown for promising spectroscopic and imaging techniques, such as fluorescence, diffuse reflectance, Raman and near-infrared spectroscopy, optical coherence tomography, and confocal laser-scanning microscopy. We review the use of these spectroscopic techniques as noninvasive tools for the photodiagnosis of NMSC.

Spectroscopic methods for the photodiagnosis of nonmelanoma skin cancer

NASA Astrophysics Data System (ADS)

Drakaki, Eleni; Vergou, Theognosia; Dessinioti, Clio; Stratigos, Alexander J.; Salavastru, Carmen; Antoniou, Christina

2013-06-01

The importance of dermatological noninvasive imaging techniques has increased over the last decades, aiming at diagnosing nonmelanoma skin cancer (NMSC). Technological progress has led to the development of various analytical tools, enabling the in vivo/in vitro examination of lesional human skin with the aim to increase diagnostic accuracy and decrease morbidity and mortality. The structure of the skin layers, their chemical composition, and the distribution of their compounds permits the noninvasive photodiagnosis of skin diseases, such as skin cancers, especially for early stages of malignant tumors. An important role in the dermatological diagnosis and disease monitoring has been shown for promising spectroscopic and imaging techniques, such as fluorescence, diffuse reflectance, Raman and near-infrared spectroscopy, optical coherence tomography, and confocal laser-scanning microscopy. We review the use of these spectroscopic techniques as noninvasive tools for the photodiagnosis of NMSC.

Acoustic pressure measurement of pulsed ultrasound using acousto-optic diffraction

NASA Astrophysics Data System (ADS)

Jia, Lecheng; Chen, Shili; Xue, Bin; Wu, Hanzhong; Zhang, Kai; Yang, Xiaoxia; Zeng, Zhoumo

2018-01-01

Compared with continuous ultrasound wave, pulsed ultrasound has been widely used in ultrasound imaging. The aim of this work is to show the applicability of acousto-optic diffraction on pulsed ultrasound transducer. In this paper, acoustic pressure of two ultrasound transducers is measured based on Raman-Nath diffraction. The frequencies of transducers are 5MHz and 10MHz. The pulse-echo method and simulation data are used to evaluate the results. The results show that the proposed method is capable to measure the absolute sound pressure. We get a sectional view of acoustic pressure using a displacement platform as an auxiliary. Compared with the traditional sound pressure measurement methods, the proposed method is non-invasive with high sensitivity and spatial resolution.

Tissue Damage Characterization Using Non-invasive Optical Modalities

NASA Astrophysics Data System (ADS)

Diaz, David

The ability to determine the degree of cutaneous and subcutaneous tissue damage is essential for proper wound assessment and a significant factor for determining patient treatment and morbidity. Accurate characterization of tissue damage is critical for a number of medical applications including surgical removal of nonviable tissue, severity assessment of subcutaneous ulcers, and depth assessment of visually open wounds. The main objective of this research was to develop a non-invasive method for identifying the extent of tissue damage underneath intact skin that is not apparent upon visual examination. This work investigated the relationship between tissue optical properties, blood flow, and tissue viability by testing the hypotheses that (a) changes in tissue oxygenation and/or microcirculatory blood flow measurable by Diffuse Near Infrared Spectroscopy (DNIRS) and Diffuse Correlation Spectroscopy (DCS) differ between healthy and damaged tissue and (b) the magnitude of those changes differs for different degrees of tissue damage. This was accomplished by developing and validating a procedure for measuring microcirculatory blood flow and tissue oxygenation dynamics at multiple depths (up to 1 centimeter) using non-invasive DCS and DNIRS technologies. Due to the lack of pressure ulcer animal models that are compatible with our optical systems, a proof of concept was conducted in a porcine burn model prior to conducting clinical trials in order to assess the efficacy of the system in-vivo. A reduction in total hemoglobin was observed for superficial (5%) and deep burns (35%) along with a statistically significant difference between the optical properties of superficial and deep burns (p < 0.05). Burn depth and viable vessel density were estimated via histological samples. 42% of vessels in the dermal layer were viable for superficial burns, compared to 25% for deep burns. The differences detected in optical properties and hemoglobin content by optical measurements correlated with the extent of tissue injury observed in histological stains. After proof of concept in animals, a human study was conducted and optical data was collected from 20 healthy subjects and 8 patients at risk of developing pressure ulcers. Blood flow index (BFI) values from the sacral region of patients were compared with those of healthy volunteers. Prior to loading measurements, baseline BFI values were measured in subjects in lateral position. These values were systematically higher for patients who developed open ulcers than for the other research subjects. While under the loading position, patients who developed a pressure ulcer had a decrease in BFI from baseline values an order of magnitude larger than healthy subjects (p < 0.01) and patients whose redness dissipated (p < 0.01). The hyperemic response, when pressure was released as the patient was moved back to a lateral position, showed a decreasing trend from one session to the next for patients who developed open ulcers. Overall, this work presents a novel non-invasive method of pressure ulcer assessment and provides an improvement over current assessment methods. The obtained results suggest the system may potentially predict whether non-blanchable redness will develop into an advanced pressure ulcer within four weeks from initial observation.

Measurement of tissue optical properties with optical coherence tomography: Implication for noninvasive blood glucose concentration monitoring

NASA Astrophysics Data System (ADS)

Larin, Kirill V.

Approximately 14 million people in the USA and more than 140 million people worldwide suffer from diabetes mellitus. The current glucose sensing technique involves a finger puncture several times a day to obtain a droplet of blood for analysis. There have been enormous efforts by many scientific groups and companies to quantify glucose concentration noninvasively using different optical techniques. However, these techniques face limitations associated with low sensitivity, accuracy, and insufficient specificity of glucose concentrations over a physiological range. Optical coherence tomography (OCT), a new technology, is being applied for noninvasive imaging in tissues with high resolution. OCT utilizes sensitive detection of photons coherently scattered from tissue. The high resolution of this technique allows for exceptionally accurate measurement of tissue scattering from a specific layer of skin compared with other optical techniques and, therefore, may provide noninvasive and continuous monitoring of blood glucose concentration with high accuracy. In this dissertation work I experimentally and theoretically investigate feasibility of noninvasive, real-time, sensitive, and specific monitoring of blood glucose concentration using an OCT-based biosensor. The studies were performed in scattering media with stable optical properties (aqueous suspensions of polystyrene microspheres and milk), animals (New Zealand white rabbits and Yucatan micropigs), and normal subjects (during oral glucose tolerance tests). The results of these studies demonstrated: (1) capability of the OCT technique to detect changes in scattering coefficient with the accuracy of about 1.5%; (2) a sharp and linear decrease of the OCT signal slope in the dermis with the increase of blood glucose concentration; (3) the change in the OCT signal slope measured during bolus glucose injection experiments (characterized by a sharp increase of blood glucose concentration) is higher than that measured in the glucose clamping experiments (characterized by slow, controlled increase of the blood glucose concentration); and (4) the accuracy of glucose concentration monitoring may substantially be improved if optimal dimensions of the probed skin area are used. The results suggest that high-resolution OCT technique has a potential for noninvasive, accurate, and continuous glucose monitoring with high sensitivity.

Retinal pulse wave velocity measurement using spectral-domain optical coherence tomography.

PubMed

Li, Qian; Li, Lin; Fan, Shanhui; Dai, Cuixia; Chai, Xinyu; Zhou, Chuanqing

2018-02-01

The human eyes provide a natural window for noninvasive measurement of the pulse wave velocity (PWV) of small arteries. By measuring the retinal PWV, the stiffness of small arteries can be assessed, which may better detect early vascular diseases. Therefore, retinal PWV measurement has attracted increasing attention. In this study, a jump-scanning method was proposed for noninvasive measurement of retinal PWV using spectral-domain optical coherence tomography (SD-OCT). The jump-scanning method uses the phase-resolved Doppler OCT to obtain the pulse shapes. To realize PWV measurement, the jump-scanning method extracts the transit time of the pulse wave from an original OCT scanning site to another through a transient jump. The measured retinal arterial PWV of a young human subject with normal blood pressure was in the order of 20 to 30 mm/s, which was consistent with previous studies. As a comparison, PWV of 50 mm/s was measured for a young human subject with prehypertension, which was in accordance with the finding of strong association between retinal PWV and blood pressure. In summary, it is believed the proposed jump-scanning method could benefit the research and diagnosis of vascular diseases through the window of human eyes. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Near-infrared thermo-optical response of the localized reflectance of intact diabetic and nondiabetic human skin.

PubMed

Yeh, Shu-Jen; Khalil, Omar S; Hanna, Charles F; Kantor, Stanislaw

2003-07-01

We observed a difference in the thermal response of localized reflectance signal of human skin between type 2 diabetics and nondiabetics. We investigated the use of this thermo-optical behavior as the basis for a noninvasive method for the determination of the diabetic status of a subject. We used a two-site temperature differential method, which is predicated upon the measurement of localized reflectance from two areas on the surface of the skin. Each of these areas is subjected to a different thermal perturbation. The response of localized reflectance to temperature perturbation was measured and used in a classification algorithm. We used a discriminant function to classify subjects as diabetic or nondiabetic. In a prediction set of twenty-four noninvasive tests collected from six diabetic and six nondiabetic subjects, the sensitivity ranged between 73 and 100%, and the specificity ranged between 75 and 100%, depending on the thermal conditions and the probe-skin contact time. The difference in the thermo-optical response of the skin of the two groups is explained in terms of a difference in the response of cutaneous microcirculation, which is manifested as a difference in the near-infrared light absorption. Another factor is the difference in the temperature response of the scattering coefficient between the two groups, which may be caused by cutaneous structural differences induced by nonenzymatic glycation of skin protein fibers, and possibly by the difference in blood cell aggregation. (c) 2003 Society of Photo-Optical Instrumentation Engineers.

Portable non-invasive brain-computer interface: challenges and opportunities of optical modalities

NASA Astrophysics Data System (ADS)

Scholl, Clara A.; Hendrickson, Scott M.; Swett, Bruce A.; Fitch, Michael J.; Walter, Erich C.; McLoughlin, Michael P.; Chevillet, Mark A.; Blodgett, David W.; Hwang, Grace M.

2017-05-01

The development of portable non-invasive brain computer interface technologies with higher spatio-temporal resolution has been motivated by the tremendous success seen with implanted devices. This talk will discuss efforts to overcome several major obstacles to viability including approaches that promise to improve spatial and temporal resolution. Optical approaches in particular will be highlighted and the potential benefits of both Blood-Oxygen Level Dependent (BOLD) and Fast Optical Signal (FOS) will be discussed. Early-stage research into the correlations between neural activity and FOS will be explored.

Optical approach to the salivary pellicle

NASA Astrophysics Data System (ADS)

Baek, Jae Ho; Krasieva, Tatiana; Tang, Shuo; Ahn, Yehchan; Kim, Chang Soo; Vu, Diana; Chen, Zhongping; Wilder-Smith, Petra

2009-07-01

The salivary pellicle plays an important role in oral physiology, yet noninvasive in situ characterization and mapping of this layer remains elusive. The goal of this study is to develop an optical approach for the real-time, noninvasive mapping and characterization of salivary pellicles using optical coherence tomography (OCT) and optical coherence microscopy (OCM). The long-term goals are to improve diagnostic capabilities in the oral cavity, gain a better understanding of physiological and pathological processes related to the oral hard tissues, and monitor treatment responses. A salivary pellicle is incubated on small enamel cubes using human whole saliva. OCT and OCM imaging occurs at 0, 10, 30, 60 min, and 24 h. For some imaging, spherical gold nanoparticles (15 nm) are added to determine whether this would increase the optical signal from the pellicle. Multiphoton microscopy (MPM) provides the baseline information. In the saliva-incubated samples, a surface signal from the developing pellicle is visible in OCT images. Pellicle ``islands'' form, which increase in complexity over time until they merge to form a continuous layer over the enamel surface. Noninvasive, in situ time-based pellicle formation on the enamel surface is visualized and characterized using optical imaging.

Transdermal Diagnosis of Malaria Using Vapor Nanobubbles

PubMed Central

Lukianova-Hleb, Ekaterina; Bezek, Sarah; Szigeti, Reka; Khodarev, Alexander; Kelley, Thomas; Hurrell, Andrew; Berba, Michail; Kumar, Nirbhay; D’Alessandro, Umberto

2015-01-01

A fast, precise, noninvasive, high-throughput, and simple approach for detecting malaria in humans and mosquitoes is not possible with current techniques that depend on blood sampling, reagents, facilities, tedious procedures, and trained personnel. We designed a device for rapid (20-second) noninvasive diagnosis of Plasmodium falciparum infection in a malaria patient without drawing blood or using any reagent. This method uses transdermal optical excitation and acoustic detection of vapor nanobubbles around intraparasite hemozoin. The same device also identified individual malaria parasite–infected Anopheles mosquitoes in a few seconds and can be realized as a low-cost universal tool for clinical and field diagnoses. PMID:26079141

In Vivo Glucose Monitoring Using Dual-Wavelength Polarimetry to Overcome Corneal Birefringence in the Presence of Motion

PubMed Central

Malik, Bilal H.; Gresham, Vincent C.; Coté, Gerard L.

2012-01-01

Abstract Objective Over the past 35 years considerable research has been performed toward the investigation of noninvasive and minimally invasive glucose monitoring techniques. Optical polarimetry is one noninvasive technique that has shown promise as a means to ascertain blood glucose levels through measuring the glucose concentrations in the anterior chamber of the eye. However, one of the key limitations to the use of optical polarimetry as a means to noninvasively measure glucose levels is the presence of sample noise caused by motion-induced time-varying corneal birefringence. Research Design and Methods In this article our group presents, for the first time, results that show dual-wavelength polarimetry can be used to accurately detect glucose concentrations in the presence of motion-induced birefringence in vivo using New Zealand White rabbits. Results In total, nine animal studies (three New Zealand White rabbits across three separate days) were conducted. Using the dual-wavelength optical polarimetric approach, in vivo, an overall mean average relative difference of 4.49% (11.66 mg/dL) was achieved with 100% Zone A+B hits on a Clarke error grid, including 100% falling in Zone A. Conclusions The results indicate that dual-wavelength polarimetry can effectively be used to significantly reduce the noise due to time-varying corneal birefringence in vivo, allowing the accurate measurement of glucose concentration in the aqueous humor of the eye and correlating that with blood glucose. PMID:22691020

Towards multimodal detection of melanoma thickness based on optical coherence tomography and optoacoustics

NASA Astrophysics Data System (ADS)

Rahlves, M.; Varkentin, A.; Stritzel, J.; Blumenröther, E.; Mazurenka, M.; Wollweber, M.; Roth, B.

2016-03-01

Melanoma skin cancer has one of the highest mortality rates of all types of cancer if not detected at an early stage. The survival rate is highly dependent on its penetration depth, which is commonly determined by histopathology. In this work, we aim at combining optical coherence tomography and optoacoustic as a non-invasive all-optical method to measure the penetration depth of melanoma. We present our recent achievements to setup a handheld multimodal device and also results from first in vivo measurements on healthy and cancerous skin tissue, which are compared to measurements obtained by ultrasound and histopathology.

Real-time point-of-care measurement of impaired renal function in a rat acute injury model employing exogenous fluorescent tracer agents

NASA Astrophysics Data System (ADS)

Dorshow, Richard B.; Fitch, Richard M.; Galen, Karen P.; Wojdyla, Jolette K.; Poreddy, Amruta R.; Freskos, John N.; Rajagopalan, Raghavan; Shieh, Jeng-Jong; Demirjian, Sevag G.

2013-02-01

Renal function assessment is needed for the detection of acute kidney injury and chronic kidney disease. Glomerular filtration rate (GFR) is now widely accepted as the best indicator of renal function, and current clinical guidelines advocate its use in the staging of kidney disease. The optimum measure of GFR is by the use of exogenous tracer agents. However current clinically employed agents lack sensitivity or are cumbersome to use. An exogenous GFR fluorescent tracer agent, whose elimination rate could be monitored noninvasively through skin would provide a substantial improvement over currently available methods. We developed a series of novel aminopyrazine analogs for use as exogenous fluorescent GFR tracer agents that emit light in the visible region for monitoring GFR noninvasively over skin. In rats, these compounds are eliminated by the kidney with urine recovery greater than 90% of injected dose, are not broken down or metabolized in vivo, are not secreted by the renal tubules, and have clearance values similar to a GFR reference compound, iothalamate. In addition, biological half-life of these compounds measured in rats by noninvasive optical methods correlated with plasma derived methods. In this study, we show that this noninvasive methodology with our novel fluorescent tracer agents can detect impaired renal function. A 5/6th nephrectomy rat model is employed.

Diffuse optical monitoring of peripheral tissues during uncontrolled internal hemorrhage in a porcine model

PubMed Central

Vishwanath, Karthik; Gurjar, Rajan; Wolf, David; Riccardi, Suzannah; Duggan, Michael; King, David

2018-01-01

Reliable, continuous and noninvasive blood flow and hemoglobin monitoring in trauma patients remains a critical, but generally unachieved goal. Two optical sensing methods - diffuse correlation spectroscopy (DCS) and diffuse reflectance spectroscopy (DRS) – are used to monitor and detect internal hemorrhage. Specifically, we investigate if cutaneous perfusion measurements acquired using DCS and DRS in peripheral (thighs and ear-lobe) tissues could detect severe hemorrhagic shock in a porcine model. Four animals underwent high-grade hepato-portal injury in a closed abdomen, to induce uncontrolled hemorrhage and were subsequently allowed to bleed for 10 minutes before fluid resuscitation. DRS and DCS measurements of cutaneous blood flow were acquired using fiber optical probes placed on the thigh and earlobe of the animals and were obtained repeatedly starting from 1 to 5 minutes pre-injury, up to several minutes post shock. Clear changes were observed in measured optical spectra across all animals at both sites. DCS-derived cutaneous blood flow decreased sharply during hemorrhage, while DRS-derived vascular saturation and hemoglobin paralleled cardiac output. All derived optical parameters had the steepest changes during the rapid initial hemorrhage unambiguously. This suggests that a combined DCS and DRS based device might provide an easy-to-use, non-invasive, internal-hemorrhage detection system that can be used across a wide array of clinical settings. PMID:29552394

Spectral biopsy for skin cancer diagnosis: initial clinical results

NASA Astrophysics Data System (ADS)

Moy, Austin J.; Feng, Xu; Nguyen, Hieu T. M.; Zhang, Yao; Sebastian, Katherine R.; Reichenberg, Jason S.; Tunnell, James W.

2017-02-01

Skin cancer is the most common form of cancer in the United States and is a recognized public health issue. Diagnosis of skin cancer involves biopsy of the suspicious lesion followed by histopathology. Biopsies, which involve excision of the lesion, are invasive, at times unnecessary, and are costly procedures ( $2.8B/year in the US). An unmet critical need exists to develop a non-invasive and inexpensive screening method that can eliminate the need for unnecessary biopsies. To address this need, our group has reported on the continued development of a noninvasive method that utilizes multimodal spectroscopy towards the goal of a "spectral biopsy" of skin. Our approach combines Raman spectroscopy, fluorescence spectroscopy, and diffuse reflectance spectroscopy to collect comprehensive optical property information from suspicious skin lesions. We previously described an updated spectral biopsy system that allows acquisition of all three forms of spectroscopy through a single fiber optic probe and is composed of off-the-shelf OEM components that are smaller, cheaper, and enable a more clinic-friendly system. We present initial patient data acquired with the spectral biopsy system, the first from an extensive clinical study (n = 250) to characterize its performance in identifying skin cancers (basal cell carcinoma, squamous cell carcinoma, and melanoma). We also present our first attempts at analyzing this initial set of clinical data using statistical-based models, and with models currently being developed to extract biophysical information from the collected spectra, all towards the goal of noninvasive skin cancer diagnosis.

Single shot imaging through turbid medium and around corner using coherent light

NASA Astrophysics Data System (ADS)

Li, Guowei; Li, Dayan; Situ, Guohai

2018-01-01

Optical imaging through turbid media and around corner is a difficult challenge. Even a very thin layer of a turbid media, which randomly scatters the probe light, can appear opaque and hide any objects behind it. Despite many recent advances, no current method can image the object behind turbid media with single record using coherent laser illumination. Here we report a method that allows non-invasive single-shot optical imaging through turbid media and around corner via speckle correlation. Instead of being as an obstacle in forming diffractionlimited images, speckle actually can be a carrier that encodes sufficient information to imaging through visually opaque layers. Optical imaging through turbid media and around corner is experimentally demonstrated using traditional imaging system with the aid of iterative phase retrieval algorithm. Our method require neither scan of illumination nor two-arm interferometry or long-time exposure in acquisition, which has new implications in optical sensing through common obscurants such as fog, smoke and haze.

All-optical recording and stimulation of retinal neurons in vivo in retinal degeneration mice

PubMed Central

Strazzeri, Jennifer M.; Williams, David R.; Merigan, William H.

2018-01-01

Here we demonstrate the application of a method that could accelerate the development of novel therapies by allowing direct and repeatable visualization of cellular function in the living eye, to study loss of vision in animal models of retinal disease, as well as evaluate the time course of retinal function following therapeutic intervention. We use high-resolution adaptive optics scanning light ophthalmoscopy to image fluorescence from the calcium sensor GCaMP6s. In mice with photoreceptor degeneration (rd10), we measured restored visual responses in ganglion cell layer neurons expressing the red-shifted channelrhodopsin ChrimsonR over a six-week period following significant loss of visual responses. Combining a fluorescent calcium sensor, a channelrhodopsin, and adaptive optics enables all-optical stimulation and recording of retinal neurons in the living eye. Because the retina is an accessible portal to the central nervous system, our method also provides a novel non-invasive method of dissecting neuronal processing in the brain. PMID:29596518

In Vivo, Non-Invasive Characterization of Human Bone by Hybrid Broadband (600-1200 nm) Diffuse Optical and Correlation Spectroscopies.

PubMed

Konugolu Venkata Sekar, Sanathana; Pagliazzi, Marco; Negredo, Eugènia; Martelli, Fabrizio; Farina, Andrea; Dalla Mora, Alberto; Lindner, Claus; Farzam, Parisa; Pérez-Álvarez, Núria; Puig, Jordi; Taroni, Paola; Pifferi, Antonio; Durduran, Turgut

2016-01-01

Non-invasive in vivo diffuse optical characterization of human bone opens a new possibility of diagnosing bone related pathologies. We present an in vivo characterization performed on seventeen healthy subjects at six different superficial bone locations: radius distal, radius proximal, ulna distal, ulna proximal, trochanter and calcaneus. A tailored diffuse optical protocol for high penetration depth combined with the rather superficial nature of considered tissues ensured the effective probing of the bone tissue. Measurements were performed using a broadband system for Time-Resolved Diffuse Optical Spectroscopy (TRS) to assess mean absorption and reduced scattering spectra in the 600-1200 nm range and Diffuse Correlation Spectroscopy (DCS) to monitor microvascular blood flow. Significant variations among tissue constituents were found between different locations; with radius distal rich of collagen, suggesting it as a prominent location for bone related measurements, and calcaneus bone having highest blood flow among the body locations being considered. By using TRS and DCS together, we are able to probe the perfusion and oxygen consumption of the tissue without any contrast agents. Therefore, we predict that these methods will be able to evaluate the impairment of the oxygen metabolism of the bone at the point-of-care.

In Vivo, Non-Invasive Characterization of Human Bone by Hybrid Broadband (600-1200 nm) Diffuse Optical and Correlation Spectroscopies

PubMed Central

Pagliazzi, Marco; Negredo, Eugènia; Martelli, Fabrizio; Farina, Andrea; Dalla Mora, Alberto; Lindner, Claus; Farzam, Parisa; Pérez-Álvarez, Núria; Puig, Jordi; Taroni, Paola; Pifferi, Antonio; Durduran, Turgut

2016-01-01

Non-invasive in vivo diffuse optical characterization of human bone opens a new possibility of diagnosing bone related pathologies. We present an in vivo characterization performed on seventeen healthy subjects at six different superficial bone locations: radius distal, radius proximal, ulna distal, ulna proximal, trochanter and calcaneus. A tailored diffuse optical protocol for high penetration depth combined with the rather superficial nature of considered tissues ensured the effective probing of the bone tissue. Measurements were performed using a broadband system for Time-Resolved Diffuse Optical Spectroscopy (TRS) to assess mean absorption and reduced scattering spectra in the 600–1200 nm range and Diffuse Correlation Spectroscopy (DCS) to monitor microvascular blood flow. Significant variations among tissue constituents were found between different locations; with radius distal rich of collagen, suggesting it as a prominent location for bone related measurements, and calcaneus bone having highest blood flow among the body locations being considered. By using TRS and DCS together, we are able to probe the perfusion and oxygen consumption of the tissue without any contrast agents. Therefore, we predict that these methods will be able to evaluate the impairment of the oxygen metabolism of the bone at the point-of-care. PMID:27997565

Investigating different skin and gastrointestinal tract (GIT) pathologies ex vivo by autofluorescence spectroscopy and optical imaging

NASA Astrophysics Data System (ADS)

Zhelyazkova, A.; Kuzmina, I.; Borisova, E.; Penkov, N.; Genova, Ts.; Spigulis, J.; Avramov, L.

2016-01-01

The skin neoplasias are on a second place in the world statistics of cancer incidence, and gastrointestinal tract (GIT) tumours are also in the "top ten" list. For the most of cutaneous and gastrointestinal tumours could be obtained better prognoses for patients, if an earlier and precise diagnostics procedure is applied. One of the most promising approaches for development of improved diagnostic techniques, is based on optical detection, and analysis of the signatures of biological tissues for detecting the presence of pathological alterations in the investigated objects. It is important to develop and combine novel diagnostic techniques for an accurate early stage diagnosis to improve the chances for skin and GIT tumours treatment. Optical techniques are very promising methods for such noninvasive diagnosis of skin and mucosa tumours, possessing the advantages of deep imaging depth, high resolution, fast imaging speed, and noninvasive character of detection. In this study we combine autofluorescence spectroscopy and optical imaging techniques to develop more precise evaluation of the tissue pathologies investigated. We obtain chromophore maps for GIT and cutaneous samples, with better visualization of the tumours borders and margins. In addition, fluorescence spectra give us information about the early changes in chromophores' contents into the tissues during neoplasia growth.

Noninvasive monitoring intracranial pressure – A review of available modalities

PubMed Central

Khan, Marium Naveed; Shallwani, Hussain; Khan, Muhammad Ulusyar; Shamim, Muhammad Shahzad

2017-01-01

Background: Intracranial pressure (ICP) monitoring is important in many neurosurgical and neurological patients. The gold standard for monitoring ICP, however, is via an invasive procedure resulting in the placement of an intraventricular catheter, which is associated with many risks. Several noninvasive ICP monitoring techniques have been examined with the hope to replace the invasive techniques. The goal of this paper is to provide an overview of all modalities that have been used for noninvasive ICP monitoring to date. Methods: A thorough literature search was conducted on PubMed, selected articles were reviewed in completion, and pertinent data was included in the review. Results: A total of 94 publications were reviewed, and we found that over the past few decades clinicians have attempted to use a number of modalities to monitor ICP noninvasively. Conclusion: Although the intraventricular catheter remains the gold standard for monitoring ICP, several noninvasive modalities that can be used in settings when invasive monitoring is not possible are also available. In our opinion, measurement of optic nerve sheath diameter and pupillometry are the two modalities which may prove to be valid options for centers not performing invasive ICP monitoring. PMID:28480113

Optical Oxygen Micro- and Nanosensors for Plant Applications

PubMed Central

Ast, Cindy; Schmälzlin, Elmar; Löhmannsröben, Hans-Gerd; van Dongen, Joost T.

2012-01-01

Pioneered by Clark's microelectrode more than half a century ago, there has been substantial interest in developing new, miniaturized optical methods to detect molecular oxygen inside cells. While extensively used for animal tissue measurements, applications of intracellular optical oxygen biosensors are still scarce in plant science. A critical aspect is the strong autofluorescence of the green plant tissue that interferes with optical signals of commonly used oxygen probes. A recently developed dual-frequency phase modulation technique can overcome this limitation, offering new perspectives for plant research. This review gives an overview on the latest optical sensing techniques and methods based on phosphorescence quenching in diverse tissues and discusses the potential pitfalls for applications in plants. The most promising oxygen sensitive probes are reviewed plus different oxygen sensing structures ranging from micro-optodes to soluble nanoparticles. Moreover, the applicability of using heterologously expressed oxygen binding proteins and fluorescent proteins to determine changes in the cellular oxygen concentration are discussed as potential non-invasive cellular oxygen reporters. PMID:22969334

Non-invasive optical detection of esophagus cancer based on urine surface-enhanced Raman spectroscopy

NASA Astrophysics Data System (ADS)

Huang, Shaohua; Wang, Lan; Chen, Weiwei; Lin, Duo; Huang, Lingling; Wu, Shanshan; Feng, Shangyuan; Chen, Rong

2014-09-01

A surface-enhanced Raman spectroscopy (SERS) approach was utilized for urine biochemical analysis with the aim to develop a label-free and non-invasive optical diagnostic method for esophagus cancer detection. SERS spectrums were acquired from 31 normal urine samples and 47 malignant esophagus cancer (EC) urine samples. Tentative assignments of urine SERS bands demonstrated esophagus cancer specific changes, including an increase in the relative amounts of urea and a decrease in the percentage of uric acid in the urine of normal compared with EC. The empirical algorithm integrated with linear discriminant analysis (LDA) were employed to identify some important urine SERS bands for differentiation between healthy subjects and EC urine. The empirical diagnostic approach based on the ratio of the SERS peak intensity at 527 to 1002 cm-1 and 725 to 1002 cm-1 coupled with LDA yielded a diagnostic sensitivity of 72.3% and specificity of 96.8%, respectively. The area under the receive operating characteristic (ROC) curve was 0.954, which further evaluate the performance of the diagnostic algorithm based on the ratio of the SERS peak intensity combined with LDA analysis. This work demonstrated that the urine SERS spectra associated with empirical algorithm has potential for noninvasive diagnosis of esophagus cancer.

Non-invasive three-dimension control of light between turbid layers using a surface quasi-point light source for precorrection.

PubMed

Qiao, Mu; Liu, Honglin; Pang, Guanghui; Han, Shensheng

2017-08-29

Manipulating light non-invasively through inhomogeneous media is an attractive goal in many disciplines. Wavefront shaping and optical phase conjugation can focus light to a point. Transmission matrix method can control light on multiple output modes simultaneously. Here we report a non-invasive approach which enables three-dimension (3D) light control between two turbid layers. A digital optical phase conjugation mirror measured and conjugated the diffused wavefront, which originated from a quasi-point source on the front turbid layer and passed through the back turbid layer. And then, because of memory effect, the phase-conjugated wavefront could be used as a carrier wave to transport a pre-calculated wavefront through the back turbid layer. The pre-calculated wavefront could project a desired 3D light field inside the sample, which, in our experiments, consisted of two 220-grid ground glass plates spaced by a 20 mm distance. The controllable range of light, according to the memory effect, was calculated to be 80 mrad in solid angle and 16 mm on z-axis. Due to the 3D light control ability, our approach may find applications in photodynamic therapy and optogenetics. Besides, our approach can also be combined with ghost imaging or compressed sensing to achieve 3D imaging between turbid layers.

Optical sensor technology for a noninvasive continuous monitoring of blood components

NASA Astrophysics Data System (ADS)

Kraitl, Jens; Timm, Ulrich; Lewis, Elfed; Ewald, Hartmut

2010-02-01

NIR-spectroscopy and Photoplethysmography (PPG) is used for a measurement of blood components. The absorptioncoefficient of blood differs at different wavelengths. This fact is used to calculate the optical absorbability characteristics of blood which is yielding information about blood components like hemoglobin (Hb), carboxyhemoglobin (CoHb) and arterial oxygen saturation (SpO2). The measured PPG time signals and the ratio between the peak to peak pulse amplitudes are used for a measurement of these parameters. Hemoglobin is the main component of red blood cells. The primary function of Hb is the transport of oxygen from the lungs to the tissue and carbon dioxide back to the lungs. The Hb concentration in human blood is an important parameter in evaluating the physiological status of an individual and an essential parameter in every blood count. Currently, invasive methods are used to measure the Hb concentration, whereby blood is taken from the patient and subsequently analyzed. Apart from the discomfort of drawing blood samples, an added disadvantage of this method is the delay between the blood collection and its analysis, which does not allow real time patient monitoring in critical situations. A noninvasive method allows pain free continuous on-line patient monitoring with minimum risk of infection and facilitates real time data monitoring allowing immediate clinical reaction to the measured data.

Label-free optical lymphangiography: development of an automatic segmentation method applied to optical coherence tomography to visualize lymphatic vessels using Hessian filters

PubMed Central

Yousefi, Siavash; Qin, Jia; Zhi, Zhongwei

2013-01-01

Abstract. Lymphatic vessels are a part of the circulatory system that collect plasma and other substances that have leaked from the capillaries into interstitial fluid (lymph) and transport lymph back to the circulatory system. Since lymph is transparent, lymphatic vessels appear as dark hallow vessel-like regions in optical coherence tomography (OCT) cross sectional images. We propose an automatic method to segment lymphatic vessel lumen from OCT structural cross sections using eigenvalues of Hessian filters. Compared to the existing method based on intensity threshold, Hessian filters are more selective on vessel shape and less sensitive to intensity variations and noise. Using this segmentation technique along with optical micro-angiography allows label-free noninvasive simultaneous visualization of blood and lymphatic vessels in vivo. Lymphatic vessels play an important role in cancer, immune system response, inflammatory disease, wound healing and tissue regeneration. Development of imaging techniques and visualization tools for lymphatic vessels is valuable in understanding the mechanisms and studying therapeutic methods in related disease and tissue response. PMID:23922124

Critical Review of Noninvasive Optical Technologies for Wound Imaging

PubMed Central

Jayachandran, Maanasa; Rodriguez, Suset; Solis, Elizabeth; Lei, Jiali; Godavarty, Anuradha

2016-01-01

Significance: Noninvasive imaging approaches can provide greater information about a wound than visual inspection during the wound healing and treatment process. This review article focuses on various optical imaging techniques developed to image different wound types (more specifically ulcers). Recent Advances: The noninvasive optical imaging approaches in this review include hyperspectral imaging, multispectral imaging, near-infrared spectroscopy (NIRS), diffuse reflectance spectroscopy, optical coherence tomography, laser Doppler imaging, laser speckle imaging, spatial frequency domain imaging, and fluorescence imaging. The various wounds imaged using these techniques include open wounds, chronic wounds, diabetic foot ulcers, decubitus ulcers, venous leg ulcers, and burns. Preliminary work in the development and implementation of a near-infrared optical scanner for wound imaging as a noncontact hand-held device is briefly described. The technology is based on NIRS and has demonstrated its potential to differentiate a healing from nonhealing wound region. Critical Issues: While most of the optical imaging techniques can penetrate few hundred microns to a 1–2 mm from the wound surface, NIRS has the potential to penetrate deeper, demonstrating the potential to image internal wounds. Future Directions: All the technologies are currently at various stages of translational efforts to the clinic, with NIRS holding a greater promise for physiological assessment of the wounds internal, beyond the gold-standard visual assessment. PMID:27602254

Noninvasive assessment of the developing Xenopus cardiovascular system using optical coherence tomography

PubMed Central

Boppart, Stephen A.; Tearney, Gary J.; Bouma, Brett E.; Southern, James F.; Brezinski, Mark E.; Fujimoto, James G.

1997-01-01

Studies investigating normal and abnormal cardiac development are frequently limited by an inability to assess cardiovascular function within the intact organism. In this work, optical coherence tomography (OCT), a new method of micron-scale, noninvasive imaging based on the measurement of backscattered infrared light, was introduced for the high resolution assessment of structure and function in the developing Xenopus laevis cardiovascular system. Microstructural details, such as ventricular size and wall positions, were delineated with OCT at 16-μm resolution and correlated with histology. Three-dimensional representation of the cardiovascular system also was achieved by repeated cross-sectional imaging at intervals of 25 μm. In addition to structural information, OCT provides high speed in vivo axial ranging and imaging, allowing quantitative dynamic activity, such as ventricular ejection fraction, to be assessed. The sensitivity of OCT for dynamic assessment was demonstrated with an inotropic agent that altered cardiac function and dimensions. Optical coherence tomography is an attractive new technology for assessing cardiovascular development because of its high resolution, its ability to image through nontransparent structures, and its inexpensive portable design. In vivo and in vitro imaging are performed at a resolution approaching that of histopathology without the need for animal killing. PMID:9113976

Towards novel compact laser sources for non-invasive diagnostics and treatment

NASA Astrophysics Data System (ADS)

Rafailov, Edik U.; Litvinova, Karina S.; Sokolovski, Sergei G.

2015-08-01

An important field of application of lasers is biomedical optics. Here, they offer great utility for diagnosis, therapy and surgery. For the development of novel methods of laser-based biomedical diagnostics careful study of light propagation in biological tissues is necessary to enhance our understanding of the optical measurements undertaken, increase research and development capacity and the diagnostic reliability of optical technologies. Ultimately, fulfilling these requirements will increase uptake in clinical applications of laser based diagnostics and therapeutics. To address these challenges informative biomarkers relevant to the biological and physiological function or disease state of the organism must be selected. These indicators are the results of the analysis of tissues and cells, such as blood. For non-invasive diagnostics peripheral blood, cells and tissue can potentially provide comprehensive information on the condition of the human organism. A detailed study of the light scattering and absorption characteristics can quickly detect physiological and morphological changes in the cells due to thermal, chemical, antibiotic treatments, etc [1-5]. The selection of a laser source to study the structure of biological particles also benefits from the fact that gross pathological changes are not induced and diagnostics make effective use of the monochromatic directional coherence properties of laser radiation.

Transcutaneous Raman spectroscopy for assessing progress of bone-graft incorporation in bone reconstruction and repair

NASA Astrophysics Data System (ADS)

Okagbare, Paul I.; Esmonde-White, Francis W. L.; Goldstein, Steven A.; Morris, Michael D.

2011-03-01

Allografts and other bone-grafts are frequently used for a variety of reconstructive approaches in orthopaedic surgery. However, successful allograft incorporation remains uncertain. Consequently, there is significant need for methods to monitor the fate of these constructs. Only few noninvasive methods can fully assess the progress of graft incorporation and to provide information on the metabolic status of the graft, such as the mineral and matrix composition of the regenerated-tissue that may provide early indications of graft success or failure. For example, Computed-tomography and MRI provide information on the morphology of the graft/host interface. Limited information is also available from DXA. To address this challenge, we present here the implementation of a noninvasive Raman spectroscopy technique for in-vivo assessment of allograft incorporation in animal-model. In an animal use committee approved osseointegration experiment, a 3mm defect is created in rat's tibia. The defect is reconstructed using auto or allograft and Raman spectra are collected at several time-points during healing using an array of optical-fibers in contact with the skin of the rat over the tibia while the rat is anaesthetized. The array allows excitation and collection of Raman spectra through the skin at various positions around the tibia. Raman parameters such as mineral/matrix, carbonate/phosphate and cross-linking are recovered and monitored. The system is calibrated against locally-constructed phantoms that mimic the morphology, optics and spectroscopy of the rat. This new technology provides a non-invasive method for in-vivo assessment of bone-graft incorporation in animal-models and can be adapted for similar study in human subjects.

Non-invasive spectroscopic techniques in the diagnosis of non-melanoma skin cancer

NASA Astrophysics Data System (ADS)

Drakaki, E.; Sianoudis, IA; Zois, EN; Makropoulou, M.; Serafetinides, AA; Dessinioti, C.; Stefanaki, E.; Stratigos, AJ; Antoniou, C.; Katsambas, A.; Christofidou, E.

2017-11-01

The number of non-melanoma skin cancers is increasing worldwide and has become an important health and economic issue. Early detection and treatment of skin cancer can significantly improve patient outcome. Therefore there is an increase in the demand for proper management and effective non-invasive diagnostic modalities in order to avoid relapses or unnecessary treatments. Although the gold standard of diagnosis for non-melanoma skin cancers is biopsy followed by histopathology evaluation, optical non-invasive diagnostic tools have obtained increased attention. Emerging non-invasive or minimal invasive techniques with possible application in the diagnosis of non-melanoma skin cancers include high-definition optical coherence tomography, fluorescence spectroscopy, oblique incidence diffuse reflectance spectrometry among others spectroscopic techniques. Our findings establish how those spectrometric techniques can be used to more rapidly and easily diagnose skin cancer in an accurate and automated manner in the clinic.

Optical aggregometry of red blood cells associated with the blood-clotting reaction in extracorporeal circulation support.

PubMed

Sakota, Daisuke; Kosaka, Ryo; Nishida, Masahiro; Maruyama, Osamu

2016-09-01

The aggregability of red blood cell (RBCs) is associated with the contribution of plasma proteins, such as fibrinogen and lipoproteids, to blood-clotting. Hence, we hypothesized that RBC aggregability reflects the blood-clotting reaction. A noninvasive optical monitoring method to measure RBC aggregability for the assessment of blood-clotting stage during mechanical circulatory support was developed. An in vitro thrombogenic test was conducted with a rotary blood pump using heparinized fresh porcine blood. Near-infrared laser light at a wavelength of 785 nm was guided by an optical fiber. The fibers for detecting incident, forward-, and backward-scattered light were fixed on the circuit tubing with an inner diameter of 1/4 inch. Because there is substantial RBC aggregation at low shear flow rates, a pulsatile flow was generated by controlling the pump rotational speed. The flow rate was changed from 0 to 8.5 L/min at a period of 40 s. The intensities of forward- and backward-scattered light changed dramatically when the flow stopped. The aggregability was evaluated by the increase ratio of the transmitted light intensity from the flow stopping in the low-flow condition. The experiment started when the anticoagulation was stopped by the addition of protamine into the circulating blood. Reduction in RBC aggregability was associated with a decrease in the amount of fibrinogen and the number of platelets. Continuous, noninvasive monitoring of thrombosis risk is possible using optical measurements combining pulsatile flow control of a rotary blood pump. RBC aggregometry is a potential label-free method for evaluating blood-clotting risk.

Analysis of retinal capillaries in patients with type 1 diabetes and nonproliferative diabetic retinopathy using adaptive optics imaging.

PubMed

Lombardo, Marco; Parravano, Mariacristina; Serrao, Sebastiano; Ducoli, Pietro; Stirpe, Mario; Lombardo, Giuseppe

2013-09-01

To illustrate a noninvasive method to analyze the retinal capillary lumen caliber in patients with Type 1 diabetes. Adaptive optics imaging of the retinal capillaries were acquired in two parafoveal regions of interest in eyes with nonproliferative diabetic retinopathy and unaffected controls. Measures of the retinal capillary lumen caliber were quantified using an algorithm written in Matlab by an independent observer in a masked manner. Comparison of the adaptive optics images with red-free and color wide fundus retinography images was also assessed. Eight eyes with nonproliferative diabetic retinopathy (eight patients, study group), no macular edema, and preserved visual acuity and eight control eyes (eight healthy volunteers; control group) were analyzed. The repeatability of capillary lumen caliber measurements was 0.22 μm (3.5%) with the 95% confidence interval between 0.12 and 0.31 μm in the study group. It was 0.30 μm (4.1%) with the 95% confidence interval between 0.16 and 0.43 μm in the control group. The average capillary lumen caliber was significantly narrower in eyes with nonproliferative diabetic retinopathy (6.27 ± 1.63 μm) than in the control eyes (7.31 ± 1.59 μm, P = 0.002). The authors demonstrated a noninvasive method to analyze, with micrometric scale of resolution, the lumen of retinal capillaries. The parafoveal capillaries were narrower in patients with Type 1 diabetes and nonproliferative diabetic retinopathy than in healthy subjects, showing the potential capability of adaptive optics imaging to detect pathologic variations of the retinal microvascular structures in vaso-occlusive diseases.

In vivo imaging of the mouse model of X-linked juvenile retinoschisis with fourier domain optical coherence tomography.

PubMed

Xu, Jing; Molday, Laurie L; Molday, Robert S; Sarunic, Marinko V

2009-06-01

The purpose of this study was to investigate Fourier domain optical coherence tomography (FD OCT) as a noninvasive tool for retinal imaging in the Rs1h-knockout mouse (model for X-linked juvenile retinoschisis). A prototype spectrometer-based FD OCT system was used in combination with a custom optical beam-scanning platform. Images of the retinas from wild-type and Rs1h-knockout mice were acquired noninvasively with FD OCT with the specimen anesthetized. At the completion of the noninvasive FD OCT imaging, invasive retinal cross-sectional images (histology) were acquired from a nearby region for comparison to the FD OCT images. The retinal layers were identifiable in the FD OCT images, permitting delineation and thickness measurement of the outer nuclear layer (ONL). During FD OCT in vivo imaging of the Rs1h-knockout mouse, holes were observed in the inner nuclear layer (INL), and retinal cell disorganization was observed as a change in the backscattering intensity profile. Comparison of the ONL measurements acquired noninvasively with FD OCT to measurements taken using histology at nearby locations showed a degeneration of roughly 30% of the ONL by the age of 2 months in Rs1h-knockout mice relative to wild-type. FD OCT was demonstrated to be effective for noninvasive imaging of retinal degeneration and observation of retinal holes in Rs1h-knockout mice.

Functional Imaging of Retinal Photoreceptors and Inner Neurons Using Stimulus-Evoked Intrinsic Optical Signals

PubMed Central

Yao, Xin-Cheng; Li, Yi-Chao

2013-01-01

Retinal development is a dynamic process both anatomically and functionally. High-resolution imaging and dynamic monitoring of photoreceptors and inner neurons can provide important information regarding the structure and function of the developing retina. In this chapter, we describe intrinsic optical signal (IOS) imaging as a high spatiotemporal resolution method for functional study of living retinal tissues. IOS imaging is based on near infrared (NIR) light detection of stimulus-evoked transient change of inherent optical characteristics of the cells. With no requirement for exogenous biomarkers, IOS imaging is totally noninvasive for functional mapping of stimulus-evoked spatiotemporal dynamics of the photoreceptors and inner retinal neurons. PMID:22688714

Noninvasive imaging of oral premalignancy and malignancy

NASA Astrophysics Data System (ADS)

Wilder-Smith, Petra; Krasieva, T.; Jung, W.; You, J. S.; Chen, Z.; Osann, K.; Tromberg, B.

2005-04-01

Objectives: Early detection of cancer and its curable precursors remains the best way to ensure patient survival and quality of life. Despite significant advances in treatment, oral cancer still results in 10,000 U.S. deaths annually, mainly due to the late detection of most oral lesions. Specific aim was to use a combination of non-invasive optical in vivo technologies to test a multi-modality approach to non-invasive diagnostics of oral premalignancy and malignancy. Methods: In the hamster cheek pouch model (120 hamsters), in vivo optical coherence tomography (OCT) and optical Doppler tomography (ODT) mapped epithelial, subepithelial and vascular change throughout carcinogenesis in specific, marked sites. In vivo multi-wavelength multi-photon (MPM) and second harmonic generated (SHG) fluorescence techniques provided parallel data on surface and subsurface tissue structure, specifically collagen presence and structure, cellular presence, and vasculature. Images were diagnosed by 2 blinded, pre-standardized investigators using a standardized scale from 0-6 for all modalities. After sacrifice, histopathological sections were prepared and pathology evaluated on a scale of 0-6. ANOVA techniques compared imaging diagnostics with histopathology. 95% confidence limits of the sensitivity and specificity were established for the diagnostic capability of OCT/ODT+ MPM/SHG using ROC curves and kappa statistics. Results: Imaging data were reproducibly obtained with good accuracy. Carcinogenesis-related structural and vascular changes were clearly visible to tissue depths of 2mm. Sensitivity (OCT/ODT alone: 71-88%; OCT+MPM/SHG: 79-91%) and specificity (OCT alone: 62-83%;OCT+MPM/SHG: 67-90%) compared well with conventional techniques. Conclusions: OCT/ODT and MPM/SHG are promising non-invasive in vivo diagnostic modalities for oral dysplasia and malignancy. Supported by CRFA 30003, CCRP 00-01391V-20235, NIH (LAMMP) RR01192, DOE DE903-91ER 61227, NIH EB-00293 CA91717, NSF BES-86924, AFOSR FA 9550-04-1-0101.

Noninvasive laser vasectomy

NASA Astrophysics Data System (ADS)

Cilip, Christopher Michael

Development of a noninvasive vasectomy technique may eliminate male fear of complications (incision, bleeding, infection, and scrotal pain) and result in a more popular procedure. These studies build off previous studies that report the ability to thermally target tissue substructures with near infrared laser radiation while maintaining a healthy superficial layer of tissue through active surface cooling. Initial studies showed the ability to increase the working depth compared to that of common dermatological procedures and the translation into an ex vivo canine model targeting the vas deferens in a noninvasive laser vasectomy. Laser and cooling parameter optimization was required to determine the best possible wavelength for a safe transition to an in vivo canine model. Optical clearing agents were investigated as a mechanism to decrease tissue scattering during in vivo procedures to increase optical penetration depth and reduce the overall power required. Optical and thermal computer models were developed to determine the efficacy for a successful transition into a human model. Common clinical imaging modalities (ultrasound, high frequency ultrasound, and optical coherence tomography) were tested as possible candidates for real-time imaging feedback to determine surgical success. Finally, a noninvasive laser vasectomy prototype clamp incorporating laser, cooling, and control in a single package was designed and tested in vivo. Occlusion of the canine vas deferens able to withstand physiological burst pressures measured postoperative was shown during acute and chronic studies. This procedure is ready for azoospermia and recanalization studies in a clinical setting.

Non-invasive optical detection of glucose in cell culture nutrient medium

NASA Technical Reports Server (NTRS)

Cote, Gerald L.

1993-01-01

The objective of the proposed research was to begin the development of a non-invasive optical sensor for measuring glucose concentration in the output medium of cell cultures grown in a unique NASA bioreactor referred to as an integrated rotating-wall vessel (IRWV). The input, a bovine serum based nutrient media, has a known glucose concentration. The cells within the bioreactor digest a portion of the glucose. Thus, the non-invasive optical sensor is needed to monitor the decrease in glucose due to cellular consumption since the critical parameters for sustained cellular productivity are glucose and pH. Previous glucose sensing techniques have used chemical reactions to quantify the glucose concentration. Chemical reactions, however, cannot provide for continuous, real time, non-invasive measurement as is required in this application. Our effort while in the fellowship program was focused on the design, optical setup, and testing of one bench top prototype non-invasive optical sensor using a mid-infrared absorption spectroscopy technique. Glucose has a fundamental vibrational absorption peak in the mid-infrared wavelength range at 9.6 micron. Preliminary absorption data using a CO2 laser were collected at this wavelength for water based glucose solutions at different concentrations and one bovine serum based nutrient medium (GTSF) with added glucose. The results showed near linear absorption responses for the glucose-in-water data with resolutions as high at 108 mg/dl and as low as 10 mg/dl. The nutrient medium had a resolution of 291 mg/dl. The variability of the results was due mainly to thermal and polarization drifts of the laser while the decrease in sensitivity to glucose in the nutrient medium was expected due to the increase in the number of confounders present in the nutrient medium. A multispectral approach needs to be used to compensate for these confounders. The CO2 laser used for these studies was wavelength tunable (9.2 to 10.8 micrometers), however, it was to unstable across wavelengths to test the multispectral approach. From this research, further NASA support was obtained to continue the work throughout the year in which a more stable light source will be used at smaller, near-infrared, wavelengths. It is anticipated that a more compact, non-invasive, optical glucose sensor will be realized which can be used with a bioreactor on future space shuttle missions. It is also anticipated that a multispectral optical sensor may be used to determine the concentration of other molecules needed within the NASA bioreactor, such as fructose and galactose.

Optical coherence tomography imaging for evaluating the photo biomodulation effects on tissue regeneration in the oral cavity

NASA Astrophysics Data System (ADS)

Gimbel, Craig B.

2008-03-01

Optical Coherence Tomography (OCT) is a noninvasive method for imaging dental microstructure which has the potential of evaluating the health of periodontal tissue. OCT provides an "optical biopsy" of tissue 2-3 mm in depth. Optical biopsy is a measurement of the localized optical properties based on tissue type and pathology. This sixth modality of imaging was pioneered at Lawrence Livermore National Laboratory. OCT is based on the optical scattering signatures within tissue structure. With the use of a broad spectrum bandwidth light source, high resolution images, 10 times the resolution of radiographs, can detect important tissue interfaces within the periodontal sulcus and its' relationship to the attachment apparatus of the tooth. Multiple cross-sectional tomograms can be stacked to create two and three dimensional images providing information as to health of periodontal tissue important to both the clinician and researcher.

Automated identification of cone photoreceptors in adaptive optics retinal images.

PubMed

Li, Kaccie Y; Roorda, Austin

2007-05-01

In making noninvasive measurements of the human cone mosaic, the task of labeling each individual cone is unavoidable. Manual labeling is a time-consuming process, setting the motivation for the development of an automated method. An automated algorithm for labeling cones in adaptive optics (AO) retinal images is implemented and tested on real data. The optical fiber properties of cones aided the design of the algorithm. Out of 2153 manually labeled cones from six different images, the automated method correctly identified 94.1% of them. The agreement between the automated and the manual labeling methods varied from 92.7% to 96.2% across the six images. Results between the two methods disagreed for 1.2% to 9.1% of the cones. Voronoi analysis of large montages of AO retinal images confirmed the general hexagonal-packing structure of retinal cones as well as the general cone density variability across portions of the retina. The consistency of our measurements demonstrates the reliability and practicality of having an automated solution to this problem.

Applicability of confocal laser scanning microscopy for evaluation and monitoring of cutaneous wound healing

NASA Astrophysics Data System (ADS)

Lange-Asschenfeldt, Susanne; Bob, Adrienne; Terhorst, Dorothea; Ulrich, Martina; Fluhr, Joachim; Mendez, Gil; Roewert-Huber, Hans-Joachim; Stockfleth, Eggert; Lange-Asschenfeldt, Bernhard

2012-07-01

There is a high demand for noninvasive imaging techniques for wound assessment. In vivo reflectance confocal laser scanning microscopy (CLSM) represents an innovative optical technique for noninvasive evaluation of normal and diseased skin in vivo at near cellular resolution. This study was designed to test the feasibility of CLSM for noninvasive analysis of cutaneous wound healing in 15 patients (7 male/8 female), including acute and chronic, superficial and deep dermal skin wounds. A commercially available CLSM system was used for the assessment of wound bed and wound margins in order to obtain descriptive cellular and morphological parameters of cutaneous wound repair noninvasively and over time. CLSM was able to visualize features of cutaneous wound repair in epidermal and superficial dermal wounds, including aspects of inflammation, neovascularisation, and tissue remodelling in vivo. Limitations include the lack of mechanic fixation of the optical system on moist surfaces restricting the analysis of chronic skin wounds to the wound margins, as well as a limited optical resolution in areas of significant slough formation. By describing CLSM features of cutaneous inflammation, vascularisation, and epithelialisation, the findings of this study support the role of CLSM in modern wound research and management.

[Design of high-efficiency double compound parabolic concentrator system in near infrared noninvasive biochemical analysis].

PubMed

Gao, Jing; Lu, Qi-Peng; Peng, Zhong-Qi; Ding, Hai-Quan; Gao, Hong-Zhi

2013-05-01

High signal-to-noise ratio (SNR) of system is necessary to obtain accurate blood components in near infrared noninvasive biochemical analysis. In order to improve SNR of analytical system, high-efficiency double compound parabolic concentrator (DCPC) system was researched, which was aimed at increasing light utilization efficiency. Firstly, with the request of collection efficiency in near infrared noninvasive biochemical analysis, the characteristic of emergent rays through compound parabolic concentrator (CPC) was analyzed. Then the maximum focusing angle range of the first stage CPC was determined. Secondly, the light utilization efficiency of truncated type was compared with standard DCPC, thus the best structure parameters of DCPC system were optimized. Lastly, combined with optical parameters of skin tissue, calculations were operated when incident wavelength is 1 000 nm. The light utilization efficiency of DCPC system, CPC-focusing mirror system, and non-optical collecting system was calculated. The results show that the light utilization efficiency of the three optical systems is 1.46%, 0.84% and 0.26% respectively. So DCPC system enhances collecting ability for human diffuse reflection light, and helps improve SNR of noninvasive biochemical analysis system and overall analysis accuracy effectively.

Comparison of the photothermal effects of 808nm gold nanorod and indocyanine green solutions using an 805nm diode laser

NASA Astrophysics Data System (ADS)

Hasanjee, Aamr M.; Zhou, Feifan; West, Connor; Silk, Kegan; Doughty, Austin; Bahavar, Cody F.; Chen, Wei R.

2016-03-01

Non-invasive laser immunotherapy (NLIT) is a treatment method for metastatic cancer which combines noninvasive laser irradiation with immunologically modified nanostructures to ablate a primary tumor and induce a systemic anti-tumor response. To further expand the development of NLIT, two different photosensitizing agents were compared: gold nanorods (GNR) with an optical absorption peak of 808 nm and indocyanine green (ICG) with an optical absorption peak of ~800 nm. Various concentrations of GNR and ICG solutions were irradiated at different power densities using an 805 nm diode laser, and the temperature of the solutions was monitored during irradiation using a thermal camera. For comparison, dye balls made up of a 1:1 volume ratio of gel solution to GNR or ICG solution were placed in phantom gels and were then irradiated using the 805 nm diode laser to imitate the effect of laser irradiation on in vivo tumors. Non-invasive laser irradiation of GNR solution for 2 minutes resulted in a maximum increase in temperature by 31.8 °C. Additionally, similar irradiation of GNR solution dye ball within phantom gel for 10 minutes resulted in a maximum temperature increase of 8.2 °C. Comparatively, non-invasive laser irradiation of ICG solution for 2 minutes resulted in a maximum increase in temperature by 28.0 °C. Similar irradiation of ICG solution dye ball within phantom gel for 10 minutes yielded a maximum temperature increase of only 3.4 °C. Qualitatively, these studies showed that GNR solutions are more effective photosensitizing agents than ICG solution.

Noninvasive imaging of human foveal capillary network using dual-conjugate adaptive optics.

PubMed

Popovic, Zoran; Knutsson, Per; Thaung, Jörgen; Owner-Petersen, Mette; Sjöstrand, Johan

2011-04-22

To demonstrate noninvasive imaging of human foveal capillary networks with a high-resolution, wide-field, dual-conjugate adaptive optics (DCAO) imaging instrument. The foveal capillary networks of five healthy subjects with no previous history of ocular or neurologic disease or surgery were imaged with a novel high-resolution, wide-field DCAO instrument. The foveal avascular zone (FAZ) in each image was defined using a manual procedure. An automated algorithm based on publicly available and custom-written software was used to identify vessels and extract morphologic FAZ and vessel parameters. Capillary densities were calculated in two annular regions of interest (ROIs) outside the FAZ (500 μm and 750 μm outer radius from the foveal center) and in the superior, inferior, temporal, and nasal quadrants within the two ROIs. Mean FAZ area was 0.302 ± 0.100 mm(2), and mean capillary density (length/area) in the inner ROI was 38.0 ± 4.0 mm(-1) and 36.4 ± 4.0 mm(-1) in the outer ROI. The difference in ROI capillary density was not significant. There was no significant difference in quadrant capillary density within the two ROIs or between quadrants irrespective of ROI. The authors have demonstrated a technique for noninvasive imaging and semiautomated detection and analysis of foveal capillaries. In comparison with other studies, their method yielded lower capillary densities than histology but similar results to the current clinical gold standard, fluorescein angiography. The increased field of view of the DCAO instrument opens up new possibilities for high-resolution noninvasive clinical imaging of foveal capillaries.

Toward noninvasive detection and monitoring of malaria with broadband diffuse optical spectroscopy

NASA Astrophysics Data System (ADS)

Campbell, Chris; Tromberg, Bruce J.; O'Sullivan, Thomas D.

2018-02-01

Despite numerous advances, malaria continues to kill nearly half a million people globally every year. New analytical methods and diagnostics are critical to understanding how treatments under development affect the lifecycle of malaria parasites. A biomarker that has been gaining interest is the "malaria pigment" hemozoin. This byproduct of hemoglobin digestion by the parasite has a unique spectral signature but is difficult to differentiate from hemoglobin and other tissue chromophores. Hemozoin can be detected in blood samples, but only utilizing approaches that require specialized training and facilities. Diffuse optical spectroscopy (DOS) is a noninvasive sensing technique that is sensitive to near-infrared absorption and scattering and capable of probing centimeter-deep volumes of tissue in vivo. DOS is relatively low-cost, does not require specialized training and thus potentially suitable for use in low-resource settings. In this work, we assess the potential of DOS to detect and quantify the presence of hemozoin noninvasively and at physiologically relevant levels. We suspended synthetic hemozoin in Intralipid-based tissue-simulating phantoms in order to mimic malaria infection in multiply-scattering tissue. Using a fiber probe that combines frequency-domain and continuous-wave broadband DOS (650-1000 nm), we detected hemozoin concentrations below 250 ng/ml, which corresponds to parasitemia sensitivities comparable to modern rapid diagnostic tests. We used the experimental variability to simulate and estimate the sensitivity of DOS to hemozoin in tissue that includes hemoglobin, water, and lipid under various tissue oxygen saturation levels. The results indicate that with increased precision, it may be possible to detect Hz noninvasively with DOS.

The practical application of reflectance spectrophotometry for the demonstration of haemoglobin and its degradation in bruises

PubMed Central

Hughes, V K; Ellis, P S; Burt, T; Langlois, N E I

2004-01-01

Aims: To develop a non-invasive method to demonstrate the presence of haemoglobin and its degradation products in bruises in live human subjects for the purposes of objectively assisting in the determination of the age of a bruise. Methods: The cuvette holder unit of a Cary 100 Bio UV-Visible Spectrophotometer was replaced with the manufacture’s fibre optic cable and optical reflectance probe. The probe was placed on the skin surface. The absorption spectrum from 780 to 380 nm was collected and transformed into the first derivative. Calculation of the first derivative permits absorption attributed to haemoglobin degradation (primarily to bilirubin, but also haemosiderin) to be separated from absorption by haemoglobin. First derivative and colorimetry values, expressed as CIEL*a*b data, were derived from scans of 50 bruises. Results: The fibre optic cable and probe allowed the spectrophotometer to collect reproducible absorption spectra of bruises in the skin of living subjects. A bruise at three days has greater negative first derivative values at 480 and 490 nm than does a fresh bruise, indicating the local degradation of haemoglobin. Correlation between the first derivative and the CIEL*a*b “b” values in a series of bruises indicates that the yellow colour in a bruise is proportional to the amount of local haemoglobin breakdown. Conclusion: The ability to demonstrate the presence of haemoglobin and measure its degradation in bruises in living human subjects by a non-invasive method has not been described previously, and may be of use in the objective ageing of bruises for forensic purposes. PMID:15047735

Nondestructive quantification of analyte diffusion in cornea and sclera using optical coherence tomography.

PubMed

Ghosn, Mohamad G; Tuchin, Valery V; Larin, Kirill V

2007-06-01

Noninvasive functional imaging, monitoring, and quantification of analytes transport in epithelial ocular tissues are extremely important for therapy and diagnostics of many eye diseases. In this study the authors investigated the capability of optical coherence tomography (OCT) for noninvasive monitoring and quantification of diffusion of different analytes in sclera and cornea of rabbit eyes. A portable time-domain OCT system with wavelength of 1310 +/- 15 nm, output power of 3.5 mW, and resolution of 25 mum was used in this study. Diffusion of different analytes was monitored and quantified in rabbit cornea and sclera of whole eyeballs. Diffusion of water, metronidazole (0.5%), dexamethasone (0.2%), ciprofloxacin (0.3%), mannitol (20%), and glucose solution (20%) were examined, and their permeability coefficients were calculated by using OCT signal slope and depth-resolved amplitude methods. Permeability coefficients were calculated as a function of time and tissue depth. For instance, mannitol was found to have a permeability coefficient of (8.99 +/- 1.43) x 10(-6) cm/s in cornea and (6.18 +/- 1.08) x 10(-6) cm/s in sclera. The permeability coefficient of drugs with small concentrations (where water was the major solvent) was found to be in the range of that of water in the same tissue type, whereas permeability coefficients of higher concentrated solutions varied significantly. Results suggest that the OCT technique might be a powerful tool for noninvasive diffusion studies of different analytes in ocular tissues. However, additional methods of OCT signal acquisition and processing are required to study the diffusion of agents of small concentrations.

Optical imaging modalities: From design to diagnosis of skin cancer

NASA Astrophysics Data System (ADS)

Korde, Vrushali Raj

This study investigates three high resolution optical imaging modalities to better detect and diagnose skin cancer. The ideal high resolution optical imaging system can visualize pre-malignant tissue growth non-invasively with resolution comparable to histology. I examined 3 modalities which approached this goal. The first method examined was high magnification microscopy of thin stained tissue sections, together with a statistical analysis of nuclear chromatin patterns termed Karyometry. This method has subcellular resolution, but it necessitates taking a biopsy at the desired tissue site and imaging the tissue ex-vivo. My part of this study was to develop an automated nuclear segmentation algorithm to segment cell nuclei in skin histology images for karyometric analysis. The results of this algorithm were compared to hand segmented cell nuclei in the same images, and it was concluded that the automated segmentations can be used for karyometric analysis. The second optical imaging modality I investigated was Optical Coherence Tomography (OCT). OCT is analogous to ultrasound, in which sound waves are delivered into the body and the echo time and reflected signal magnitude are measured. Due to the fast speed of light and detector temporal integration times, low coherence interferometry is needed to gate the backscattered light. OCT acquires cross sectional images, and has an axial resolution of 1-15 mum (depending on the source bandwidth) and a lateral resolution of 10-20 mum (depending on the sample arm optics). While it is not capable of achieving subcellular resolution, it is a non-invasive imaging modality. OCT was used in this study to evaluate skin along a continuum from normal to sun damaged to precancer. I developed algorithms to detect statistically significant differences between images of sun protected and sun damaged skin, as well as between undiseased and precancerous skin. An Optical Coherence Microscopy (OCM) endoscope was developed in the third portion of this study. OCM is a high resolution en-face imaging modality. It is a hybrid system that combines the principles of confocal microscopy with coherence gating to provide an increased imaging depth. It can also be described as an OCT system with a high NA objective. Similar to OCT, the axial resolution is determined by the source center wavelength and bandwidth. The NA of the sample arm optics determines the lateral resolution, usually on the order of 1-5 mum. My effort on this system was to develop a handheld endoscope. To my knowledge, an OCM endoscope has not been developed prior to this work. An image of skin was taken as a proof of concept. This rigid handheld OCM endoscope will be useful for applications ranging from minimally invasive surgical imaging to non-invasively assessing dysplasia and sun damage in skin.

In vivo light scattering for the detection of cancerous and precancerous lesions of the cervix

PubMed Central

Mourant, Judith R.; Powers, Tamara M.; Bocklage, Thérese J.; Greene, Heather M.; Dorin, Maxine H.; Waxman, Alan G.; Zsemlye, Meggan M.; Smith, Harriet O.

2009-01-01

A non-invasive optical diagnostic system for detection of cancerous and precancerous lesions of the cervix was evaluated, in vivo. The optical system included a fiber optic probe designed to measure polarized and unpolarized light transport properties of a small volume of tissue. An algorithm for diagnosing tissue based on the optical measurements was developed which used four optical properties, three of which were related to light scattering properties and the fourth of which was related to hemoglobin concentration. A sensitivity of ∼77% and specificities in the mid 60's were obtained for separating high grade squamous intraepithelial lesions and cancer from other pathologies and normal tissue. The use of different cross-validation methods in algorithm development is analyzed and the relative difficulties of diagnosing certain pathologies is assessed. Furthermore, the robustness of the optical system for use by different doctors and to changes in fiber optic probe were also assessed and potential improvements in the optical system are discussed. PMID:19340117

Multiphoton microscopy for the in-situ investigation of cellular processes and integrity in cryopreservation.

PubMed

Doerr, Daniel; Stark, Martin; Ehrhart, Friederike; Zimmermann, Heiko; Stracke, Frank

2009-08-01

In this study we demonstrate a new noninvasive imaging method to monitor freezing processes in biological samples and to investigate life in the frozen state. It combines a laser scanning microscope with a computer-controlled cryostage. Nearinfrared (NIR) femtosecond laser pulses evoke the fluorescence of endogenous fluorophores and fluorescent labels due to multiphoton absorption.The inherent optical nonlinearity of multiphoton absorption allows 3D fluorescence imaging for optical tomography of frozen biological material in-situ. As an example for functional imaging we use fluorescence lifetime imaging (FLIM) to create images with chemical and physical contrast.

Noninvasive optical quantification of absolute blood flow, blood oxygenation, and oxygen consumption rate in exercising skeletal muscle

NASA Astrophysics Data System (ADS)

Gurley, Katelyn; Shang, Yu; Yu, Guoqiang

2012-07-01

This study investigates a method using novel hybrid diffuse optical spectroscopies [near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS)] to obtain continuous, noninvasive measurement of absolute blood flow (BF), blood oxygenation, and oxygen consumption rate (\\Vdot O2) in exercising skeletal muscle. Healthy subjects (n=9) performed a handgrip exercise to increase BF and \\Vdot O2 in forearm flexor muscles, while a hybrid optical probe on the skin surface directly monitored oxy-, deoxy-, and total hemoglobin concentrations ([HbO2], [Hb], and THC), tissue oxygen saturation (StO2), relative BF (rBF), and relative oxygen consumption rate (r\\Vdot O2). The rBF and r\\Vdot O2 signals were calibrated with absolute baseline BF and \\Vdot O2 obtained through venous and arterial occlusions, respectively. Known problems with muscle-fiber motion artifacts in optical measurements during exercise were mitigated using a novel gating algorithm that determined muscle contraction status based on control signals from a dynamometer. Results were consistent with previous findings in the literature. This study supports the application of NIRS/DCS technology to quantitatively evaluate hemodynamic and metabolic parameters in exercising skeletal muscle and holds promise for improving diagnosis and treatment evaluation for patients suffering from diseases affecting skeletal muscle and advancing fundamental understanding of muscle and exercise physiology.

Noninvasive optical quantification of absolute blood flow, blood oxygenation, and oxygen consumption rate in exercising skeletal muscle

PubMed Central

Gurley, Katelyn; Shang, Yu

2012-01-01

Abstract. This study investigates a method using novel hybrid diffuse optical spectroscopies [near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS)] to obtain continuous, noninvasive measurement of absolute blood flow (BF), blood oxygenation, and oxygen consumption rate (V˙O2) in exercising skeletal muscle. Healthy subjects (n=9) performed a handgrip exercise to increase BF and V˙O2 in forearm flexor muscles, while a hybrid optical probe on the skin surface directly monitored oxy-, deoxy-, and total hemoglobin concentrations ([HbO2], [Hb], and THC), tissue oxygen saturation (StO2), relative BF (rBF), and relative oxygen consumption rate (rV˙O2). The rBF and rV˙O2 signals were calibrated with absolute baseline BF and V˙O2 obtained through venous and arterial occlusions, respectively. Known problems with muscle-fiber motion artifacts in optical measurements during exercise were mitigated using a novel gating algorithm that determined muscle contraction status based on control signals from a dynamometer. Results were consistent with previous findings in the literature. This study supports the application of NIRS/DCS technology to quantitatively evaluate hemodynamic and metabolic parameters in exercising skeletal muscle and holds promise for improving diagnosis and treatment evaluation for patients suffering from diseases affecting skeletal muscle and advancing fundamental understanding of muscle and exercise physiology. PMID:22894482

Investigation of pH and temperature on optical rotatory dispersion for noninvasive glucose monitoring

NASA Astrophysics Data System (ADS)

Baba, Justin S.; Meledeo, Adam; Cameron, B. D.; Cote, Gerard L.

2001-06-01

The widespread occurrence of diabetes mellitus and the severity of its associated complications necessitate the development of non-invasive blood glucose measurement devices in an attempt to improve treatment regimens and curb the complications associated with this disease. One method showing promise in this endeavor utilizes optical polarimetry to monitor blood glucose levels indirectly by measuring glucose rotation of polarized light, which is a direct indication of glucose concentration, in the aqueous humor of the eye. The presence of other optically active (chiral) components in the aqueous humor of the eye have the potential to confound the glucose measurement of optical rotation when using a single wavelength polarimeter. Thus, this has led to the recent investigation of multispectral polarimetric systems which have the potential to enable the removal of confounder contributions to the net observed optical rotation, therefore, increasing glucose specificity and reducing glucose prediction errors. Such polarimetric systems take advantage of the uniqueness in the rotation of polarized light, as a function of wavelength, by the chiral molecule of interest. This is commonly referred to as the optical rotatory dispersion (ORD) spectra of the chiral molecule. ORD characterization of the chiral molecules within the aqueous humor is necessary for determining the optimum number of wavelengths needed to reduce glucose prediction errors; however, this information is often only given at the sodium-D line (589 nm) in the literature. This report describes the system we designed and built to measure ORD spectra for glucose and for albumin, the main optical confounder within the aqueous humor, as well as our investigation of the effects of temperature and pH on these ORD spectra.

Diagnosis of basal cell carcinoma by two photon excited fluorescence combined with lifetime imaging

NASA Astrophysics Data System (ADS)

Fan, Shunping; Peng, Xiao; Liu, Lixin; Liu, Shaoxiong; Lu, Yuan; Qu, Junle

2014-02-01

Basal cell carcinoma (BCC) is the most common type of human skin cancer. The traditional diagnostic procedure of BCC is histological examination with haematoxylin and eosin staining of the tissue biopsy. In order to reduce complexity of the diagnosis procedure, a number of noninvasive optical methods have been applied in skin examination, for example, multiphoton tomography (MPT) and fluorescence lifetime imaging microscopy (FLIM). In this study, we explored two-photon optical tomography of human skin specimens using two-photon excited autofluorescence imaging and FLIM. There are a number of naturally endogenous fluorophores in skin sample, such as keratin, melanin, collagen, elastin, flavin and porphyrin. Confocal microscopy was used to obtain structures of the sample. Properties of epidermic and cancer cells were characterized by fluorescence emission spectra, as well as fluorescence lifetime imaging. Our results show that two-photon autofluorescence lifetime imaging can provide accurate optical biopsies with subcellular resolution and is potentially a quantitative optical diagnostic method in skin cancer diagnosis.

Non-invasive sex assessment in bovine semen by Raman spectroscopy

NASA Astrophysics Data System (ADS)

De Luca, A. C.; Managó, S.; Ferrara, M. A.; Rendina, I.; Sirleto, L.; Puglisi, R.; Balduzzi, D.; Galli, A.; Ferraro, P.; Coppola, G.

2014-05-01

X- and Y-chromosome-bearing sperm cell sorting is of great interest, especially for animal production management systems and genetic improvement programs. Here, we demonstrate an optical method based on Raman spectroscopy to separate X- and Y-chromosome-bearing sperm cells, overcoming many of the limitations associated with current sex-sorting protocols. A priori Raman imaging of bull spermatozoa was utilized to select the sampling points (head-neck region), which were then used to discriminate cells based on a spectral classification model. Main variations of Raman peaks associated with the DNA content were observed together with a variation due to the sex membrane proteins. Next, we used principal component analysis to determine the efficiency of our device as a cell sorting method. The results (>90% accuracy) demonstrated that Raman spectroscopy is a powerful candidate for the development of a highly efficient, non-invasive, and non-destructive tool for sperm sexing.

Application to Noninvasive Measurement of Blood Components Based on Infrared Spectroscopy

NASA Astrophysics Data System (ADS)

Tamura, Kazuto; Ishizawa, Hiroaki; Fujita, Keiichi; Kaneko, Wataru; Morikawa, Tomotaka; Toba, Eiji; Kobayashi, Hideo

Recently, lifestyle diseases (diabetics, hyperlipemia etc.) have been steadily increasing, because change of diet, lack of exercise, increase an alcoholic intake, and increase a stress. It is a matter of vital importance to us. About tens of millions of people in Japan have approached the danger of lifestyle diseases. So they have to do a blood test to make sure that they have controlled physical condition themselves. Therefore, they have to measure blood components again and again. So, they are burden too heavy. This paper describes a new noninvasive measurement of blood components based on optical sensing. This uses Fourier transform infrared spectroscopy of attenuated total reflection. In order to study, the influence of individual difference, the internal standard method was introduced. This paper describes the detail of the internal standard method and its effect to the blood components calibration. Significant improvement was obtained by using the internal standard.

Near-infrared spectral methods for noninvasively measuring blood glucose

NASA Astrophysics Data System (ADS)

Fei, Sun; Kong, Deyi; Mei, Tao; Tao, Yongchun

2004-05-01

Determination of blood glucose concentrations in diabetic patients is a frequently occurring procedure and an important tool for diabetes management. Use of noninvasive detection techniques can relieve patients from the pain of frequent finger pokes and avoid the infection of disease via blood. This thesis discusses current research and analyzes the advantages and shortages of different measurement methods, including: optical methods (Transmission, Polarimetry and scattering), then, we give emphasis to analyze the technology of near-infrared (NIR) spectra. NIR spectral range 700 nm ~2300 nm was used because of its good transparency for biological tissue and presence of glucose absorption band. In this work, we present an outline of noninvasive blood glucose measurement. A near-infrared light beam is passed through the finger, and the spectral components of the emergent beam are measured using spectroscopic techniques. The device includes light sources having the wavelengths of 600 nm - 1800 nm to illuminate the tissue. Receptors associated with the light sources for receiving light and generating a transmission signal representing the light transmitted are also provided. Once a transmission signal is received by receptors, and the high and low values from each of the signals are stored in the device. The averaged values are then analyzed to determine the glucose concentration, which is displayed on the device.

Noninvasive detection of macular pigments in the human eye.

PubMed

Gellermann, Werner; Bernstein, Paul S

2004-01-01

There is currently strong interest in developing noninvasive technologies for the detection of macular carotenoid pigments in the human eye. These pigments, consisting of lutein and zeaxanthin, are taken up from the diet and are thought to play an important role in the prevention of age-related macular degeneration, the leading cause of blindness in the elderly in the Western world. It may be possible to prevent or delay the onset of this debilitating disease with suitable dietary intervention strategies. We review the most commonly used detection techniques based on heterochromatic flicker photometry, fundus reflectometry, and autofluorescense techniques and put them in perspective with recently developed more molecule-specific Raman detection methods. (c) 2004 Society of Photo-Optical Instrumentation Engineers.

Noninvasive diagnostics of skin microphysical parameters based on spatially resolved diffuse reflectance spectroscopy

NASA Astrophysics Data System (ADS)

Lisenko, S. A.; Kugeiko, M. M.

2013-01-01

The ability to determine noninvasively microphysical parameters (MPPs) of skin characteristic of malignant melanoma was demonstrated. The MPPs were the melanin content in dermis, saturation of tissue with blood vessels, and concentration and effective size of tissue scatterers. The proposed method was based on spatially resolved spectral measurements of skin diffuse reflectance and multiple regressions between linearly independent measurement components and skin MPPs. The regressions were established by modeling radiation transfer in skin with a wide variation of its MPPs. Errors in the determination of skin MPPs were estimated using fiber-optic measurements of its diffuse reflectance at wavelengths of commercially available semiconductor diode lasers (578, 625, 660, 760, and 806 nm) at source-detector separations of 0.23-1.38 mm.

Non-invasive assessment of hemispheric language dominance by optical topography during a brief passive listening test: a pilot study.

PubMed

Bembich, Stefano; Demarini, Sergio; Clarici, Andrea; Massaccesi, Stefano; Grasso, Domenico Loenardo

2011-12-01

The Wada test is usually used for pre-surgical assessment of language lateralization. Considering its invasiveness and risk of complications, alternative methods have been proposed but they are not always applicable to non-cooperative patients. In this study we explored the possibility of using optical topography (OT)--a multichannel near-infrared system--for non-invasive assessment of hemispheric language dominance during passive listening. Cortical activity was monitored in a sample of healthy, adult Italian native speakers, all right-handed. We assessed changes in oxy-haemoglobin concentration in temporal, parietal and posterior frontal lobes during a passive listening of bi-syllabic words and vowel-consonant-vowel syllables lasting less then 3 minutes. Activated channels were identified by t tests. Left hemisphere showed significant activity only during the passive listening of bi-syllabic words. Specifically, the superior temporal gyrus, the supramarginal gyrus and the posterior inferior parietal lobe were activated. During passive listening of bi-syllabic words, right handed healthy adults showed a significant activation in areas already known to be involved in speech comprehension. Although more research is needed, OT proved to be a promising alternative to the Wada test for non-invasive assessment of hemispheric language lateralization, even if using a particularly brief trial, which has been designed for future applications with non-cooperative subjects.

Noninvasive imaging analysis of biological tissue associated with laser thermal injury.

PubMed

Chang, Cheng-Jen; Yu, De-Yi; Hsiao, Yen-Chang; Ho, Kuang-Hua

2017-04-01

The purpose of our study is to use a noninvasive tomographic imaging technique with high spatial resolution to characterize and monitor biological tissue responses associated with laser thermal injury. Optical doppler tomography (ODT) combines laser doppler flowmetry (LDF) with optical coherence tomography (OCT) to obtain high resolution tomographic velocity and structural images of static and moving constituents in highly scattering biological tissues. A SurgiLase XJ150 carbon dioxide (CO 2 ) laser using a continuous mode of 3 watts (W) was used to create first, second or third degree burns on anesthetized Sprague-Dawley rats. Additional parameters for laser thermal injury were assessed as well. The rationale for using ODT in the evaluation of laser thermal injury offers a means of constructing a high resolution tomographic image of the structure and perfusion of laser damaged skin. In the velocity images, the blood flow is coded at 1300 μm/s and 0 velocity, 1000 μm/s and 0 velocity, 700 μm/s and 0 velocity adjacent to the first, second, and third degree injuries, respectively. ODT produces exceptional spatial resolution while having a non-invasive way of measurement, therefore, ODT is an accurate measuring method for high-resolution fluid flow velocity and structural images for biological tissue with laser thermal injury. Copyright © 2017 Chang Gung University. Published by Elsevier B.V. All rights reserved.

Optical wavelength selection for portable hemoglobin determination by near-infrared spectroscopy method

NASA Astrophysics Data System (ADS)

Tian, Han; Li, Ming; Wang, Yue; Sheng, Dinggao; Liu, Jun; Zhang, Linna

2017-11-01

Hemoglobin concentration is commonly used in clinical medicine to diagnose anemia, identify bleeding, and manage red blood cell transfusions. The golden standard method for determining hemoglobin concentration in blood requires reagent. Spectral methods were advantageous at fast and non-reagent measurement. However, model calibration with full spectrum is time-consuming. Moreover, it is necessary to use a few variables considering size and cost of instrumentation, especially for a portable biomedical instrument. This study presents different wavelength selection methods for optical wavelengths for total hemoglobin concentration determination in whole blood. The results showed that modelling using only two wavelengths combination (1143 nm, 1298 nm) can keep on the fine predictability with full spectrum. It appears that the proper selection of optical wavelengths can be more effective than using the whole spectra for determination hemoglobin in whole blood. We also discussed the influence of water absorptivity on the wavelength selection. This research provides valuable references for designing portable NIR instruments determining hemoglobin concentration, and may provide some experience for noninvasive hemoglobin measurement by NIR methods.

Computer-aided, multi-modal, and compression diffuse optical studies of breast tissue

NASA Astrophysics Data System (ADS)

Busch, David Richard, Jr.

Diffuse Optical Tomography and Spectroscopy permit measurement of important physiological parameters non-invasively through ˜10 cm of tissue. I have applied these techniques in measurements of human breast and breast cancer. My thesis integrates three loosely connected themes in this context: multi-modal breast cancer imaging, automated data analysis of breast cancer images, and microvascular hemodynamics of breast under compression. As per the first theme, I describe construction, testing, and the initial clinical usage of two generations of imaging systems for simultaneous diffuse optical and magnetic resonance imaging. The second project develops a statistical analysis of optical breast data from many spatial locations in a population of cancers to derive a novel optical signature of malignancy; I then apply this data-derived signature for localization of cancer in additional subjects. Finally, I construct and deploy diffuse optical instrumentation to measure blood content and blood flow during breast compression; besides optics, this research has implications for any method employing breast compression, e.g., mammography.

Multi-modal approach using Raman spectroscopy and optical coherence tomography for the discrimination of colonic adenocarcinoma from normal colon

PubMed Central

Ashok, Praveen C.; Praveen, Bavishna B.; Bellini, Nicola; Riches, Andrew; Dholakia, Kishan; Herrington, C. Simon

2013-01-01

We report a multimodal optical approach using both Raman spectroscopy and optical coherence tomography (OCT) in tandem to discriminate between colonic adenocarcinoma and normal colon. Although both of these non-invasive techniques are capable of discriminating between normal and tumour tissues, they are unable individually to provide both the high specificity and high sensitivity required for disease diagnosis. We combine the chemical information derived from Raman spectroscopy with the texture parameters extracted from OCT images. The sensitivity obtained using Raman spectroscopy and OCT individually was 89% and 78% respectively and the specificity was 77% and 74% respectively. Combining the information derived using the two techniques increased both sensitivity and specificity to 94% demonstrating that combining complementary optical information enhances diagnostic accuracy. These data demonstrate that multimodal optical analysis has the potential to achieve accurate non-invasive cancer diagnosis. PMID:24156073

Noninvasive optical coherence tomography monitoring of structure and hydration changes of human corneas in different preservation media

NASA Astrophysics Data System (ADS)

Wu, Yicong; Clarke, Dominic; Mathew, Aby; Nicoud, Ian; Li, Xingde

2011-02-01

The influence of different tissue preservation (a test solution under development and a standard storage solution) on human cornea morphology, refractive index and hydration was assessed noninvasively by ultrahigh-resolution optical coherence tomography (OCT) over time. For 28 days' or 15 days' storage in the preservation media, corneas in the two media exhibited different structural changes with different onset times including epithelial desquamation, edema-induced cornea thickening and change in tissue refractive index. It was found that the variation of the group refractive index over time was only about 2%, while 25% variation of hydration was observed in the storage and subsequent return to normothermic conditions in both preservation media. The results suggest the two media involved different but correlated preservation mechanisms. This study demonstrates that the noncontact, noninvasive, and high-resolution OCT is a powerful tool for noninvasive characterization of tissue morphological changes and hydration process and for assessment of the effects of preservation media on stored tissue integrity. Engineers.

A non-invasive diffuse reflectance calibration-free method for absolute determination of exogenous biochemicals concentration in biological tissues

NASA Astrophysics Data System (ADS)

Lappa, Alexander V.; Kulikovskiy, Artem N.; Busarov, Oleg G.

2014-03-01

The paper presents a new method for distant non-destructive determination of concentration of light absorbing admixtures in turbid media. In particular, it is intended for non-invasive in vivo control of accumulation in patient tissues of various biochemicals introduced to the patients for chemotherapy, photodynamic therapy or diagnostics. It is require that the admixture absorption spectrum should have a clearly marked peak in the wavelength region where the pure medium one varies regularly. Fluorescence of admixtures is not required. The method uses the local diffuse reflectance spectroscopy with optical fiber probe including one emitting and two reading There are several features in the method: the value to be determined is absolute concentration of admixtures; the method needs no calibration measurements on phantoms; it needs no reference measurements on sample with zero admixture concentration; it uses a two parametric kinetic light propagation model and original algorithms to resolve direct and inverse tasks of radiation transport theory. Experimental testing passed with tissue equivalent phantoms and different admixtures, including a chlorine photosensitizer, showed accuracy under 10% in all cases.

Simulations and experiments of photon propagation in biological tissue and liquid crystal waveguides

NASA Astrophysics Data System (ADS)

Lines, Collin M.

The development of non-invasive methods to probe human tissue is an ongoing challenge in biomedical optics. In vivo measurements by conventional methods are limited by the mean free path (MFP) of a photon, which is governed by the spatial distribution of chromophores and the absorption and scattering properties of the tissue. As one of the strongest chromophores in human tissues, hemoglobin concentrations in human tissue greatly affect the MFP of photons in visible wavelengths (i.e. bruising). Changes in the concentration of hemoglobin and other chromophores within the tissue (minor trauma causing a contusion, increased bilirubin due to jaundice, etc.) will affect the MFP, leading to a visibly different appearance (color) of the tissue. As color perception is a complex physiological process, these changes are diffcult to quantify by human observation alone. The transport of hemoglobin and its breakdown products in tissue is related to a number of medical conditions that could benefit from a non-invasive method to determine the hemoglobin levels.

Portable method of measuring gaseous acetone concentrations.

PubMed

Worrall, Adam D; Bernstein, Jonathan A; Angelopoulos, Anastasios P

2013-08-15

Measurement of acetone in human breath samples has been previously shown to provide significant non-invasive diagnostic insight into the control of a patient's diabetic condition. In patients with diabetes mellitus, the body produces excess amounts of ketones such as acetone, which are then exhaled during respiration. Using various breath analysis methods has allowed for the accurate determination of acetone concentrations in exhaled breath. However, many of these methods require instrumentation and pre-concentration steps not suitable for point-of-care use. We have found that by immobilizing resorcinol reagent into a perfluorosulfonic acid polymer membrane, a controlled organic synthesis reaction occurs with acetone in a dry carrier gas. The immobilized, highly selective product of this reaction (a flavan) is found to produce a visible spectrum color change which could measure acetone concentrations to less than ppm. We here demonstrate how this approach can be used to produce a portable optical sensing device for real-time, non-invasive acetone analysis. Copyright © 2013 Elsevier B.V. All rights reserved.

Monitoring blood glucose changes in cutaneous tissue by temperature-modulated localized reflectance measurements.

PubMed

Yeh, Shu-Jen; Hanna, Charles F; Khalil, Omar S

2003-06-01

Most proposed noninvasive methods for glucose measurements do not consider the physiologic response of the body to changes in glucose concentration. Rather than consider the body as an inert matrix for the purpose of glucose measurement, we exploited the possibility that noninvasive measurements of glucose can be approached by investigating their effects on the skin's thermo-optical response. Glucose concentrations in humans were correlated with temperature-modulated localized reflectance signals at wavelengths between 590 and 935 nm, which do not correspond to any near-infrared glucose absorption wavelengths. Optical signal was collected while skin temperature was modulated between 22 and 38 degrees C over 2 h to generate a periodic set of cutaneous vasoconstricting and vasodilating events, as well as a periodic change in skin light scattering. The method was tested in a series of modified meal tolerance tests involving carbohydrate-rich meals and no-meal or high-protein/no-carbohydrate meals. The optical data correlated with glucose values. Changes in glucose concentrations resulting from a carbohydrate-rich meal were predicted with a model based on a carbohydrate-meal calibration run. For diabetic individuals, glucose concentrations were predicted with a standard error of prediction <1.5 mmol/L and a prediction correlation coefficient 0.73 in 80% of the cases. There were run-to-run differences in predicted glucose concentrations. Non-carbohydrate meals showed a high degree of scatter when predicted by a carbohydrate meal calibration model. Blood glucose concentrations alter thermally modulated optical signals, presumably through physiologic and physical effects. Temperature changes drive cutaneous vascular and refractive index responses in a way that mimics the effect of changes in glucose concentration. Run-to-run differences are attributable to site-to-site structural differences.

Ultrahigh-resolution optical coherence microscopy accurately classifies precancerous and cancerous human cervix free of labeling

PubMed Central

Zeng, Xianxu; Zhang, Xiaoan; Li, Canyu; Wang, Xiaofang; Jerwick, Jason; Xu, Tao; Ning, Yuan; Wang, Yihong; Zhang, Linlin; Zhang, Zhan; Ma, Yutao; Zhou, Chao

2018-01-01

Cervical cancer remains the fourth most common cause of cancer worldwide and the third leading cause of cancer deaths for women in developing countries. Traditional screening tools, such as human papillomavirus and Pap tests, cannot provide results in real-time and cannot localize suspicious regions. Colposcopy-directed biopsies are invasive in nature and only a few sites of the cervix may be chosen for investigation. A non-invasive, label-free and real-time imaging method with a resolution approaching that of histopathology is desirable for early detection of the disease. Methods: Ultrahigh-resolution optical coherence microscopy (OCM) is an emerging imaging technique used to obtain 3-dimensional (3-D) “optical biopsies” of biological samples with cellular resolution. In this study, 497 3-D OCM datasets from 159 specimens were collected from 92 patients. Results: Distinctive patterns for normal cervix, squamocolumnar junction, ectropion, low-grade and high-grade squamous intraepithelial lesions (LSIL and HSIL) and invasive cervical lesions were clearly observed from OCM images, which matched well with corresponding histological slides. OCM images demonstrated a sensitivity of 80% (95% confidence interval, CI, 72%-86%) and a specificity of 89% (95% CI, 84%-93%) for detecting high-risk lesions (HSIL and invasive lesions) when blindly tested by three investigators. A substantial inter-observer agreement was observed (κ=0.627), which showed high diagnostic consistency among three investigators. Conclusion: These results laid the foundation for future non-invasive optical evaluation of cervical tissue in vivo, which could lead to a less invasive and more effective screening and “see-and-treat” strategy for the management of cervical cancer. PMID:29896305

Effects of optical clearing agents on noninvasive blood glucose monitoring with optical coherence tomography: a pilot study

NASA Astrophysics Data System (ADS)

He, Ruoyu; Wei, Huajiang; Gu, Huimin; Zhu, Zhengguo; Zhang, Yuqing; Guo, Xiao; Cai, Tiantian

2012-10-01

Recently, the capability of optical coherence tomography (OCT) has been demonstrated for noninvasive blood glucose monitoring. In this work, we investigate the administration of chemical agents onto human skin tissue to increase the transparency of the surface of the skin, as a means of improving the capability of OCT imaging for clinically relevant applications. Eight groups of experiments were proposed, in which different optical clearing agents (OCA) were used. The results indicate that, when properly used, some OCAs perform well in promoting the capability of OCT for noninvasive blood glucose monitoring. Among the four kinds of OCA we used, 50% v/v glycerol solute turns out to be the best enhancer. Compared with the results of the experiments in which no OCA was used, when 50% glycerol was applied onto the human skin topically, the correlation coefficient between the OCT signal slope (OCTSS) and blood glucose concentration (BGC) was improved by 7.1% on average, and the lag time between changes in the OCTSS and BGC was cut by 8 min on average. The results of 10 w/v mannitol were also good, but not as pronounced.

Non-invasive characterization of structure and morphology of silk fibroin biomaterials using non-linear microscopy

PubMed Central

Rice, William L.; Firdous, Shamaraz; Gupta, Sharad; Hunter, Martin; Foo, Cheryl Wong Po; Wang, Yongzhong; Kim, Hyeon Joo; Kaplan, David L.; Georgakoudi, Irene

2009-01-01

Designing biomaterial scaffolds remains a major challenge in tissue engineering. Key to this challenge is improved understanding of the relationships between the scaffold properties and its degradation kinetics, as well as the cell interactions and the promotion of new matrix deposition. Here we present the use of non-linear spectroscopic imaging as a non-invasive method to characterize not only morphological, but also structural aspects of silkworm silk fibroin-based biomaterials, relying entirely on endogenous optical contrast. We demonstrate that two photon excited fluorescence and second harmonic generation are sensitive to the hydration, overall β sheet content and molecular orientation of the sample. Thus, the functional content and high resolution afforded by these non-invasive approaches offer promise for identifying important connections between biomaterial design and functional engineered tissue development. The strategies described also have broader implications for understanding and tracking the remodeling of degradable biomaterials under dynamic conditions both in vitro and in vivo. PMID:18291520

Noninvasive hemoglobin measurement using dynamic spectrum

NASA Astrophysics Data System (ADS)

Yi, Xiaoqing; Li, Gang; Lin, Ling

2017-08-01

Spectroscopy methods for noninvasive hemoglobin (Hgb) measurement are interfered by individual difference and particular weak signal. In order to address these problems, we have put forward a series of improvement methods based on dynamic spectrum (DS), including instrument design, spectrum extraction algorithm, and modeling approach. The instrument adopts light sources composed of eight laser diodes with the wavelength range from 600 nm to 1100 nm and records photoplethysmography signals at eight wavelengths synchronously. In order to simplify the optical design, we modulate the light sources with orthogonal square waves and design the corresponding demodulation algorithm, instead of adopting a beam-splitting system. A newly designed algorithm named difference accumulation has been proved to be effective in improving the accuracy of dynamic spectrum extraction. 220 subjects are involved in the clinical experiment. An extreme learning machine calibration model between the DS data and the Hgb levels is established. Correlation coefficient and root-mean-square error of prediction sets are 0.8645 and 8.48 g/l, respectively. The results indicate that the Hgb level can be derived by this approach noninvasively with acceptable precision and accuracy. It is expected to achieve a clinic application in the future.

A simple one-step method to prepare fluorescent carbon dots and their potential application in non-invasive glioma imaging

NASA Astrophysics Data System (ADS)

Ruan, Shaobo; Qian, Jun; Shen, Shun; Zhu, Jianhua; Jiang, Xinguo; He, Qin; Gao, Huile

2014-08-01

Fluorescent carbon dots (CD) possess impressive potential in bioimaging because of their low photobleaching, absence of optical blinking and good biocompatibility. However, their relatively short excitation/emission wavelengths restrict their application in in vivo imaging. In the present study, a kind of CD was prepared by a simple heat treatment method using glycine as the only precursor. The diameter of CD was lower than 5 nm, and the highest emission wavelength was 500 nm. However, at 600 nm, there was still a relatively strong fluorescent emission, suggesting CD could be used for in vivo imaging. Additionally, several experiments demonstrated that CD possessed good serum stability and low cytotoxicity. In vitro, CD could be taken up into C6 glioma cells in a time- and concentration-dependent manner, with both endosomes and mitochondria involved. In vivo, CD could be used for non-invasive glioma imaging because of its high accumulation in the glioma site of the brain, which was demonstrated by both in vivo imaging and ex vivo tissue imaging. Furthermore, the fluorescent distribution in tissue slices also showed CD distributed in glioma with high intensity, while with a low intensity in normal brain tissue. In conclusion, CD were prepared using a simple method with relatively long excitation and emission wavelengths and could be used for non-invasive glioma imaging.Fluorescent carbon dots (CD) possess impressive potential in bioimaging because of their low photobleaching, absence of optical blinking and good biocompatibility. However, their relatively short excitation/emission wavelengths restrict their application in in vivo imaging. In the present study, a kind of CD was prepared by a simple heat treatment method using glycine as the only precursor. The diameter of CD was lower than 5 nm, and the highest emission wavelength was 500 nm. However, at 600 nm, there was still a relatively strong fluorescent emission, suggesting CD could be used for in vivo imaging. Additionally, several experiments demonstrated that CD possessed good serum stability and low cytotoxicity. In vitro, CD could be taken up into C6 glioma cells in a time- and concentration-dependent manner, with both endosomes and mitochondria involved. In vivo, CD could be used for non-invasive glioma imaging because of its high accumulation in the glioma site of the brain, which was demonstrated by both in vivo imaging and ex vivo tissue imaging. Furthermore, the fluorescent distribution in tissue slices also showed CD distributed in glioma with high intensity, while with a low intensity in normal brain tissue. In conclusion, CD were prepared using a simple method with relatively long excitation and emission wavelengths and could be used for non-invasive glioma imaging. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr02657h

Nanometer resolution optical coherence tomography using broad bandwidth XUV and soft x-ray radiation

DOE PAGES

Fuchs, Silvio; Rödel, Christian; Blinne, Alexander; ...

2016-02-10

Optical coherence tomography (OCT) is a non-invasive technique for cross-sectional imaging. It is particularly advantageous for applications where conventional microscopy is not able to image deeper layers of samples in a reasonable time, e.g. in fast moving, deeper lying structures. However, at infrared and optical wavelengths, which are commonly used, the axial resolution of OCT is limited to about 1 μm, even if the bandwidth of the light covers a wide spectral range. Here, we present extreme ultraviolet coherence tomography (XCT) and thus introduce a new technique for non-invasive cross-sectional imaging of nanometer structures. XCT exploits the nanometerscale coherence lengthsmore » corresponding to the spectral transmission windows of, e.g., silicon samples. The axial resolution of coherence tomography is thus improved from micrometers to a few nanometers. Tomographic imaging with an axial resolution better than 18 nm is demonstrated for layer-type nanostructures buried in a silicon substrate. Using wavelengths in the water transmission window, nanometer-scale layers of platinum are retrieved with a resolution better than 8 nm. As a result, XCT as a nondestructive method for sub-surface tomographic imaging holds promise for several applications in semiconductor metrology and imaging in the water window.« less

Noninvasive optical cytochrome c oxidase redox state measurements using diffuse optical spectroscopy

PubMed Central

Lee, Jangwoen; Kim, Jae G.; Mahon, Sari B.; Mukai, David; Yoon, David; Boss, Gerry R.; Patterson, Steven E.; Rockwood, Gary; Isom, Gary; Brenner, Matthew

2014-01-01

Abstract. A major need exists for methods to assess organ oxidative metabolic states in vivo. By contrasting the responses to cyanide (CN) poisoning versus hemorrhage in animal models, we demonstrate that diffuse optical spectroscopy (DOS) can detect cytochrome c oxidase (CcO) redox states. Intermittent decreases in inspired O2 from 100% to 21% were applied before, during, and after CN poisoning, hemorrhage, and resuscitation in rabbits. Continuous DOS measurements of total hemoglobin, oxyhemoglobin, deoxyhemoglobin, and oxidized and reduced CcO from muscle were obtained. Rabbit hemorrhage was accomplished with stepwise removal of blood, followed by blood resuscitation. CN treated rabbits received 0.166  mg/min NaCN infusion. During hemorrhage, CcO redox state became reduced concurrently with decreases in oxyhemoglobin, resulting from reduced tissue oxygen delivery and hypoxia. In contrast, during CN infusion, CcO redox state decreased while oxyhemoglobin concentration increased due to CN binding and reduction of CcO with resultant inhibition of the electron transport chain. Spectral absorption similarities between hemoglobin and CcO make noninvasive spectroscopic distinction of CcO redox states difficult. By contrasting physiological perturbations of CN poisoning versus hemorrhage, we demonstrate that DOS measured CcO redox state changes are decoupled from hemoglobin concentration measurement changes. PMID:24788369

Noninvasive optical cytochrome c oxidase redox state measurements using diffuse optical spectroscopy

NASA Astrophysics Data System (ADS)

Lee, Jangwoen; Kim, Jae G.; Mahon, Sari B.; Mukai, David; Yoon, David; Boss, Gerry R.; Patterson, Steven E.; Rockwood, Gary; Isom, Gary; Brenner, Matthew

2014-05-01

A major need exists for methods to assess organ oxidative metabolic states in vivo. By contrasting the responses to cyanide (CN) poisoning versus hemorrhage in animal models, we demonstrate that diffuse optical spectroscopy (DOS) can detect cytochrome c oxidase (CcO) redox states. Intermittent decreases in inspired O2 from 100% to 21% were applied before, during, and after CN poisoning, hemorrhage, and resuscitation in rabbits. Continuous DOS measurements of total hemoglobin, oxyhemoglobin, deoxyhemoglobin, and oxidized and reduced CcO from muscle were obtained. Rabbit hemorrhage was accomplished with stepwise removal of blood, followed by blood resuscitation. CN treated rabbits received 0.166 mg/min NaCN infusion. During hemorrhage, CcO redox state became reduced concurrently with decreases in oxyhemoglobin, resulting from reduced tissue oxygen delivery and hypoxia. In contrast, during CN infusion, CcO redox state decreased while oxyhemoglobin concentration increased due to CN binding and reduction of CcO with resultant inhibition of the electron transport chain. Spectral absorption similarities between hemoglobin and CcO make noninvasive spectroscopic distinction of CcO redox states difficult. By contrasting physiological perturbations of CN poisoning versus hemorrhage, we demonstrate that DOS measured CcO redox state changes are decoupled from hemoglobin concentration measurement changes.

Invasive and non-invasive measurement in medicine and biology: calibration issues

NASA Astrophysics Data System (ADS)

Rolfe, P.; Zhang, Yan; Sun, Jinwei; Scopesi, F.; Serra, G.; Yamakoshi, K.; Tanaka, S.; Yamakoshi, T.; Yamakoshi, Y.; Ogawa, M.

2010-08-01

Invasive and non-invasive measurement sensors and systems perform vital roles in medical care. Devices are based on various principles, including optics, photonics, and plasmonics, electro-analysis, magnetics, acoustics, bio-recognition, etc. Sensors are used for the direct insertion into the human body, for example to be in contact with blood, which constitutes Invasive Measurement. This approach is very challenging technically, as sensor performance (sensitivity, response time, linearity) can deteriorate due to interactions between the sensor materials and the biological environment, such as blood or interstitial fluid. Invasive techniques may also be potentially hazardous. Alternatively, sensors or devices may be positioned external to the body surface, for example to analyse respired breath, thereby allowing safer Non-Invasive Measurement. However, such methods, which are inherently less direct, often requiring more complex calibration algorithms, perhaps using chemometric principles. This paper considers and reviews the issue of calibration in both invasive and non-invasive biomedical measurement systems. Systems in current use usually rely upon periodic calibration checks being performed by clinical staff against a variety of laboratory instruments and QC samples. These procedures require careful planning and overall management if reliable data are to be assured.

Multifunctional PSCA antibody fragments for PET and optical prostate cancer imaging

DTIC Science & Technology

2017-10-01

INVESTIGATOR: Anna M. Wu CONTRACTING ORGANIZATION: University of California, Los Angeles Los Angeles, CA 90095-1406 REPORT DATE : October 2017 TYPE OF...cys- minibodies and cys-diabodies) can be labeled with radioisotopes for non-invasive PET imaging for use at multiple points in the prostate cancer...optimize and test multifunctional, F-18, and alternatively labeled fragments Major Task 3. New technologies: alternative site-specific labeling methods

Optical Diagnostics in Medicine

NASA Astrophysics Data System (ADS)

Iftimia, Nicusor

2003-03-01

Light has a unique potential for non-invasive tissue diagnosis. The relatively short wavelength of light allows imaging of tissue at the resolution of histopathology. While strong multiple scattering of light in tissue makes attainment of this resolution difficult for thick tissues, most pathology emanates from epithelial surfaces. Therefore, high-resolution diagnosis of many important diseases may be achieved by transmitting light to the surface of interest. The recent fiber-optic implementation of technologies that reject multiple scattering, such as confocal microscopy and optical low coherence interferometry, have brought us one step closer to realizing non-invasive imaging of architectural and cellular features of tissue. Optical coherence tomography (OCT) can produce high-resolution cross-sectional images of biological structures. Clinical OCT studies conducted in the gastrointestinal tract and cardiovascular system have shown that OCT is capable of providing images of the architectural (> 20 µm) microanatomy of a variety of epithelial tissues, including the layered structure of squamous epithelium and arterial vessels. Fine Needle Aspiration- Low Coherence Interferometry (FNA-LCI) is another optical diagnostics technique, which is a suitable solution to increase the effectiveness of the FNA procedures. LCI is capable of measuring depth resolved (axial, z) tissue structure, birefringence, flow (Doppler shift), and spectra at a resolution of several microns. Since LCI systems are fiber-optic based, LCI probes may easily fit within the bore of a fine gauge needle, allowing diagnostic information to be obtained directly from the FNA biopsy site. Fiber optic spectrally encoded confocal microscopy (SECM) is a new confocal microscopy method, which eliminates the need for rapid beam scanning within the optical probe. This advance enables confocal microscopy to be performed through small diameter probes and will allow assessment of internal human tissues in vivo at the cellular level. A detailed description of several fiber optics based systems for early diseases diagnosis, as well as preliminary clinic results, will be presented.

Finding the position of tumor inhomogeneities in a gel-like model of a human breast using 3-D pulsed digital holography.

PubMed

Hernández-Montes, Maria del Socorro; Pérez-López, Carlos; Santoyo, Fernando Mendoza

2007-01-01

3-D pulsed digital holography is a noninvasive optical method used to measure the depth position of breast tumor tissue immersed in a semisolid gel model. A master gel without inhomogeneities is set to resonate at an 810 Hz frequency; then, an identically prepared gel with an inhomogeneity is interrogated with the same resonant frequency in the original setup. Comparatively, and using only an out-of-plane sensitive setup, gel surface displacement can be measured, evidencing an internal inhomogeneity. However, the depth position cannot be measured accurately, since the out-of-plane component has the contribution of in-plane surface displacements. With the information gathered, three sensitivity vectors can be obtained to separate contributions from x, y, and z vibration displacement components, individual displacement maps for the three orthogonal axes can be built, and the inhomogeneity's depth position can be accurately measured. Then, the displacement normal to the gel surface is used to find the depth profile and its cross section. Results from the optical data obtained are compared and correlated to the inhomogeneity's physically measured position. Depth position is found with an error smaller than 1%. The inhomogeneity and its position within the gel can be accurately found, making the method a promising noninvasive alternative to study mammary tumors.

Contrast-enhanced optical coherence tomography with picomolar sensitivity for functional in vivo imaging

NASA Astrophysics Data System (ADS)

Liba, Orly; Sorelle, Elliott D.; Sen, Debasish; de La Zerda, Adam

2016-03-01

Optical Coherence Tomography (OCT) enables real-time imaging of living tissues at cell-scale resolution over millimeters in three dimensions. Despite these advantages, functional biological studies with OCT have been limited by a lack of exogenous contrast agents that can be distinguished from tissue. Here we report an approach to functional OCT imaging that implements custom algorithms to spectrally identify unique contrast agents: large gold nanorods (LGNRs). LGNRs exhibit 110-fold greater spectral signal per particle than conventional GNRs, which enables detection of individual LGNRs in water and concentrations as low as 250 pM in the circulation of living mice. This translates to ~40 particles per imaging voxel in vivo. Unlike previous implementations of OCT spectral detection, the methods described herein adaptively compensate for depth and processing artifacts on a per sample basis. Collectively, these methods enable high-quality noninvasive contrast-enhanced imaging of OCT in living subjects, including detection of tumor microvasculature at twice the depth achievable with conventional OCT. Additionally, multiplexed detection of spectrally-distinct LGNRs was demonstrated to observe discrete patterns of lymphatic drainage and identify individual lymphangions and lymphatic valve functional states. These capabilities provide a powerful platform for molecular imaging and characterization of tissue noninvasively at cellular resolution, called MOZART.

Non-invasive biomedical research and diagnostics enabled by innovative compact lasers

NASA Astrophysics Data System (ADS)

Litvinova, Karina S.; Rafailov, Ilya E.; Dunaev, Andrey V.; Sokolovski, Sergei G.; Rafailov, Edik U.

2017-11-01

For over half a century, laser technology has undergone a technological revolution. These technologies, particularly semiconductor lasers, are employed in a myriad of fields. Optical medical diagnostics, one of the emerging areas of laser application, are on the forefront of application around the world. Optical methods of non- or minimally invasive bio-tissue investigation offer significant advantages over alternative methods, including rapid real-time measurement, non-invasiveness and high resolution (guaranteeing the safety of a patient). These advantages demonstrate the growing success of such techniques. In this review, we will outline the recent status of laser technology applied in the biomedical field, focusing on the various available approaches, particularly utilising compact semiconductor lasers. We will further consider the advancement and integration of several complimentary biophotonic techniques into single multimodal devices, the potential impact of such devices and their future applications. Based on our own studies, we will also cover the simultaneous collection of physiological data with the aid a multifunctional diagnostics system, concentrating on the optimisation of the new technology towards a clinical application. Such data is invaluable for developing algorithms capable of delivering consistent, reliable and meaningful diagnostic information, which can ultimately be employed for the early diagnosis of disease conditions in individuals from around the world.

Non-invasive diagnosis of sweat gland dysplasia using optical coherence tomography and reflectance confocal microscopy in a family with anhidrotic ectodermal dysplasia (Christ-Siemens-Touraine syndrome).

PubMed

Reinholz, M; Gauglitz, G G; Giehl, K; Braun-Falco, M; Schwaiger, H; Schauber, J; Ruzicka, T; Berneburg, M; von Braunmühl, T

2016-04-01

Anhidrotic ectodermal dysplasia (AED) is an inherited syndrome, which originates mainly from genetic alteration of the ectodysplasin A (EDA) gene. It regularly affects the adnexa of the skin which results in a characteristic phenotype of the patients including hypo- or anhidrosis leading to severe disturbances in the regulation of body temperature. To prevent the development of the symptoms in early childhood promising therapeutic approaches are currently under clinical investigation. In this context, timely diagnosis of this genetic syndrome is crucial. The purpose of our study was the investigation of modern non-invasive imaging methods such as optical coherence tomography (OCT) and reflectance confocal microscopy (RCM) in the immediate diagnosis of AED. We examined a 3-year-old boy with the suspicion for an AED syndrome and his family members with RCM and OCT to document presence and characteristic features of sweat glands in comparison to non-affected individuals. The patient and the affected brother showed significantly reduced sweat glands in the imaging compared to the controls. The genetic analysis revealed a mutation of the EDA gene for hemizygosity previously associated with AED and the mother was revealed as the conductor of the genetic alteration. With the help of non-invasive imaging, we were able to detect sweat gland dysplasia in the affected family members without performing a biopsy which led us to the diagnosis of an AED. The application of modern dermatological imaging techniques might serve as valuable supplementary tools in the immediate, non-invasive diagnosis of genetic syndromes especially in newborns when early therapeutic approaches are planned. © 2015 European Academy of Dermatology and Venereology.

Enhanced polarizing microscopy as a new tool in aneuploidy research in oocytes.

PubMed

Shen, Ying; Betzendahl, Ilse; Tinneberg, Hans-Rudolf; Eichenlaub-Ritter, Ursula

2008-03-12

Chromosomal non-disjunction in female meiosis gives rise to reduced fertility and trisomy in humans. Human oocytes, especially from aged women, appear especially susceptible to non-disjunction. The oocyte spindle is crucial for high fidelity of chromosome segregation at meiotic divisions, and alterations in spindle morphology are therefore indicators of adverse conditions during oocyte development that may result in meiotic aneuploidy. In the past, oocytes had to be fixed for spindle analysis, precluding direct non-invasive identification of aneugens and adverse maturation conditions that affect spindle integrity and chromosome behaviour. Aneuploidy research for detection of spindle aberrations was therefore mainly focused on in vivo or in vitro exposed, fixed animal oocytes or cytogenetic analysis of spread oocytes. Orientation independent enhanced polarizing microscopy with nearly circularly polarized light and electronically controlled liquid crystal compensator optics is a new tool to study spindle morphology non-invasively in vivo for qualitative as well as quantitative analysis. Image generation by polarization microscopy depends on the intrinsic optical properties of the spindle with its paracrystalline microtubule lattice. When polarized light passes through such a lattice it induces a splitting of the beam and shift in the plane of vibration and retardation of light (termed birefringence and retardance). Studies of animal oocytes and follicle-cell denuded human oocytes fertilized by intracytoplasmic sperm injection for assisted conception have demonstrated the safety and efficacy of enhanced polarization microscopy. The method can be employed in aneuploidy research for non-invasive dose-response studies to detect spindle aberrations, for instance, in combination with cytogenetic analysis. Due to the non-invasive nature of the technique it may be employed in routine analysis of human oocytes to assess risks by lifestyle factors, and occupational and adverse environmental exposures.

Near-infrared optical imaging of nucleic acid nanocarriers in vivo.

PubMed

Rome, Claire; Gravier, Julien; Morille, Marie; Divita, Gilles; Bolcato-Bellemin, Anne-Laure; Josserand, Véronique; Coll, Jean-Luc

2013-01-01

Noninvasive, real-time optical imaging methods are well suited to follow the in vivo distribution of nucleic acid nanocarriers, their dissociation, and the resulting gene expression or inhibition. Indeed, most small animal imaging devices perform bioluminescence and fluorescence measurements without moving the animal, allowing a simple, rapid, and cost-effective method of investigation of several parameters at a time, in longitudinal experiments that can last for days or weeks.Here we help the reader in choosing adapted near-infrared (NIR) fluorophores or pairs of fluorophores for Förster resonance energy transfer assays, imaging of reporter genes, as well as nanocarriers for in vivo gene and siRNA delivery. In addition, we present the labeling methods of these macromolecules and of their payload and the protocols to detect them using bioluminescence and NIR fluorescence imaging in mice.

An innovative approach for investigating the ceramic bracket-enamel interface - optical coherence tomography and confocal microscopy

NASA Astrophysics Data System (ADS)

Romînu, Roxana Otilia; Sinescu, Cosmin; Romînu, Mihai; Negrutiu, Meda; Laissue, Philippe; Mihali, Sorin; Cuc, Lavinia; Hughes, Michael; Bradu, Adrian; Podoleanu, Adrian

2008-09-01

Bonding has become a routine procedure in several dental specialties - from prosthodontics to conservative dentistry and even orthodontics. In many of these fields it is important to be able to investigate the bonded interfaces to assess their quality. All currently employed investigative methods are invasive, meaning that samples are destroyed in the testing procedure and cannot be used again. We have investigated the interface between human enamel and bonded ceramic brackets non-invasively, introducing a combination of new investigative methods - optical coherence tomography (OCT) and confocal microscopy (CM). Brackets were conventionally bonded on conditioned buccal surfaces of teeth The bonding was assessed using these methods. Three dimensional reconstructions of the detected material defects were developed using manual and semi-automatic segmentation. The results clearly prove that OCT and CM are useful in orthodontic bonding investigations.

Near-infrared optical imaging of nucleic acid nanocarriers in vivo

PubMed Central

Rome, Claire; Gravier, Julien; Morille, Marie; Divita, Gilles; Bolcato-Bellemin, Anne-Laure; Josserand, Véronique; Coll, Jean-Luc

2013-01-01

Summary Non-invasive, real time optical imaging methods are particularly well suited for the in vivo follow up of the distribution of nucleic acids nanocarriers, their dissociation and finally the resulting gene expression or inhibition. Indeed, most small animal imaging devices are performing bioluminescence and fluorescence measurements without moving the animal, allowing a simple, rapid and cost effective method of investigation of several parameters at a time, in longitudinal experiments that can last for days or weeks. Here we propose to help the reader choosing adapted near-infrared (NIR) fluorophores or pairs of fluorophores for FRET assays, reporter genes as well as nanocarriers for in vivo gene and siRNA delivery. In addition, we present the labeling methods of these macromolecules, and of their payload and the protocols to detect them using bioluminescence and NIR fluorescence imaging in mice. PMID:23070763

Photoacoustic measurement of refractive index of dye solutions and myoglobin for biosensing applications

PubMed Central

Goldschmidt, Benjamin S.; Mehta, Smit; Mosley, Jeff; Walter, Chris; Whiteside, Paul J. D.; Hunt, Heather K.; Viator, John A.

2013-01-01

Current methods of determining the refractive index of chemicals and materials, such as ellipsometry and reflectometry, are limited by their inability to analyze highly absorbing or highly transparent materials, as well as the required prior knowledge of the sample thickness and estimated refractive index. Here, we present a method of determining the refractive index of solutions using the photoacoustic effect. We show that a photoacoustic refractometer can analyze highly absorbing dye samples to within 0.006 refractive index units of a handheld optical refractometer. Further, we use myoglobin, an early non-invasive biomarker for malignant hyperthermia, as a proof of concept that this technique is applicable for use as a medical diagnostic. Comparison of the speed, cost, simplicity, and accuracy of the techniques shows that this photoacoustic method is well-suited for optically complex systems. PMID:24298407

Occlusal overload investigations by noninvasive technology: fluorescence microscopy and en-face optical coherence tomography

NASA Astrophysics Data System (ADS)

Marcauteanu, Corina; Negrutiu, Meda; Sinescu, Cosmin; Demjan, Enikö; Hughes, Michael; Bradu, Adrian; Dobre, George; Podoleanu, Adrian G.

2009-07-01

The aim of this study is the early detection and monitoring of occlusal overload in bruxing patients. En-Face Optical coherence tomography (eF-OCT) and fluorescence microscopy (FM) were used for the imaging of several anterior teeth extracted from patients with light active bruxism. We found a characteristic pattern of enamel cracks, that reached the tooth surface. We concluded that the combination of the en-Face OCT and FM is a promising non-invasive alternative technique for reliable monitoring of occlusal overload.

A Noninvasive Miniaturized-Wireless Laser-Doppler Fiber-Optic Sensor for Understanding Distal Fingertip Injuries in Astronauts

NASA Technical Reports Server (NTRS)

Ansari, Rafat R.; Jones, Jeffrey A.; Pollonini, Luca; Rodriquez, Mikael; Opperman, Roedolph; Hochstein, Jason

2009-01-01

During extra-vehicular activities (EVAs) or spacewalks astronauts over use their fingertips under pressure inside the confined spaces of gloves/space suits. The repetitive hand motion is a probable cause for discomfort and injuries to the fingertips. We describe a new wireless fiber-optic probe that can be integrated inside the astronaut glove for noninvasive blood perfusion measurements in distal fingertips. In this preliminary study, we present blood perfusion measurements while performing hand-grip exercises simulating the use of space tools.

Current advances in molecular imaging: noninvasive in vivo bioluminescent and fluorescent optical imaging in cancer research.

PubMed

Choy, Garry; Choyke, Peter; Libutti, Steven K

2003-10-01

Recently, there has been tremendous interest in developing techniques such as MRI, micro-CT, micro-PET, and SPECT to image function and processes in small animals. These technologies offer deep tissue penetration and high spatial resolution, but compared with noninvasive small animal optical imaging, these techniques are very costly and time consuming to implement. Optical imaging is cost-effective, rapid, easy to use, and can be readily applied to studying disease processes and biology in vivo. In vivo optical imaging is the result of a coalescence of technologies from chemistry, physics, and biology. The development of highly sensitive light detection systems has allowed biologists to use imaging in studying physiological processes. Over the last few decades, biochemists have also worked to isolate and further develop optical reporters such as GFP, luciferase, and cyanine dyes. This article reviews the common types of fluorescent and bioluminescent optical imaging, the typical system platforms and configurations, and the applications in the investigation of cancer biology.

Emerging fiber optic endomicroscopy technologies towards noninvasive real-time visualization of histology in situ

NASA Astrophysics Data System (ADS)

Xi, Jiefeng; Zhang, Yuying; Huo, Li; Chen, Yongping; Jabbour, Toufic; Li, Ming-Jun; Li, Xingde

2010-09-01

This paper reviews our recent developments of ultrathin fiber-optic endomicroscopy technologies for transforming high-resolution noninvasive optical imaging techniques to in vivo and clinical applications such as early disease detection and guidance of interventions. Specifically we describe an all-fiber-optic scanning endomicroscopy technology, which miniaturizes a conventional bench-top scanning laser microscope down to a flexible fiber-optic probe of a small footprint (i.e. ~2-2.5 mm in diameter), capable of performing two-photon fluorescence and second harmonic generation microscopy in real time. This technology aims to enable realtime visualization of histology in situ without the need for tissue removal. We will also present a balloon OCT endoscopy technology which permits high-resolution 3D imaging of the entire esophagus for detection of neoplasia, guidance of biopsy and assessment of therapeutic outcome. In addition we will discuss the development of functional polymeric fluorescent nanocapsules, which use only FAD approved materials and potentially enable fast track clinical translation of optical molecular imaging and targeted therapy.

Label-free optical imaging of lymphatic vessels within tissue beds in vivo

PubMed Central

Yousefi, Siavash; Zhi, Zhongwei; Wang, Ruikang K.

2015-01-01

Lymphatic vessels are a part of circulatory system in vertebrates that maintain tissue fluid homeostasis and drain excess fluid and large cells that cannot easily find their way back into venous system. Due to the lack of non-invasive monitoring tools, lymphatic vessels are known as forgotten circulation. However, lymphatic system plays an important role in diseases such as cancer and inflammatory conditions. In this paper, we start to briefly review the current existing methods for imaging lymphatic vessels, mostly involving dye/targeting cell injection. We then show the capability of optical coherence tomography (OCT) for label-free non-invasive in vivo imaging of lymph vessels and nodes. One of the advantages of using OCT over other imaging modalities is its ability to assess label-free blood flow perfusion that can be simultaneously observed along with lymphatic vessels for imaging the microcirculatory system within tissue beds. Imaging the microcirculatory system including blood and lymphatic vessels can be utilized for imaging and better understanding pathologic mechanisms and treatment technique development in some critical diseases such as inflammation, malignant cancer angiogenesis and metastasis. PMID:25642129

Optical Spectroscopy and Multivariate Analysis for Biodosimetry and Monitoring of Radiation Injury to the Skin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levitskaia, Tatiana G.; Bryan, Samuel A.; Creim, Jeffrey A.

2012-08-01

In the event of an intentional or accidental release of ionizing radiation in a densely populated area, timely assessment and triage of the general population for the radiation exposure is critical. In particular, a significant number of the victims may sustain cutaneous radiation injury, which increases the mortality and worsens the overall prognosis of the victims suffered from combined thermal/mechanical and radiation trauma. Diagnosis of the cutaneous radiation injury is challenging, and established methods largely rely on visual manifestations, presence of the skin contamination, and a high degree of recall by the victim. Availability of a high throughput non-invasive inmore » vivo biodosimetry tool for assessment of the radiation exposure of the skin is of particular importance for the timely diagnosis of the cutaneous injury. In the reported investigation, we have tested the potential of an optical reflectance spectroscopy for the evaluation of the radiation injury to the skin. This is technically attractive because optical spectroscopy relies on well-established and routinely used for various applications instrumentation, one example being pulse oximetry which uses selected wavelengths for the quantification of the blood oxygenation. Our method relies on a broad spectral region ranging from the locally absorbed, shallow-penetrating ultraviolet and visible (250 to 800 nm) to more deeply penetrating near-Infrared (800 – 1600 nm) light for the monitoring of multiple physiological changes in the skin upon irradiation. Chemometrics is a multivariate methodology that allows the information from entire spectral region to be used to generate predictive regression models. In this report we demonstrate that simple spectroscopic method, such as the optical reflectance spectroscopy, in combination with multivariate data analysis, offers the promise of rapid and non-invasive in vivo diagnosis and monitoring of the cutaneous radiation exposure, and is able accurately predict the dose and time of exposure in the rodent model.« less

Application of optical spectroscopic techniques for disease diagnosis

NASA Astrophysics Data System (ADS)

Saha, Anushree

Optical spectroscopy, a truly non-invasive tool for remote diagnostics, is capable of providing valuable information on the structure and function of molecules. However, most spectroscopic techniques suffer from drawbacks, which limit their application. As a part of my dissertation work, I have developed theoretical and experimental methods to address the above mentioned issues. I have successfully applied these methods for monitoring the physical, chemical and biochemical parameters of biomolecules involved in some specific life threatening diseases like lead poisoning and age-related macular degeneration (AMD). I presented optical studies of melanosomes, which are one of the vital organelles in the human eye, also known to be responsible for a disease called age-related macular degeneration (AMD), a condition of advanced degeneration which causes progressive blindness. I used Raman spectroscopy, to first chemically identify the composition of melanosome, and then monitor the changes in its functional and chemical behavior due to long term exposure to visible light. The above study, apart from explaining the role of melanosomes in AMD, also sets the threshold power for lasers used in surgeries and other clinical applications. In the second part of my dissertation, a battery of spectroscopic techniques was successfully applied to explore the different binding sites of lead ions with the most abundant carrier protein molecule in our circulatory system, human serum albumin. I applied optical spectroscopic tools for ultrasensitive detection of heavy metal ions in solution which can also be used for lead detection at a very early stage of lead poisoning. Apart from this, I used Raman microspectroscopy to study the chemical alteration occurring inside a prostate cancer cell as a result of a treatment with a low concentrated aqueous extract of a prospective drug, Nerium Oleander. The experimental methods used in this study has tremendous potential for clinical application and will gain widespread acceptance within next few years from bench to bedside as an inexpensive and non-invasive tool compared to the other technologies.

Application of optical longitudinal tomography for dental introscopy

NASA Astrophysics Data System (ADS)

Levin, Gennady G.; Burgansky, Alexander A.; Levandovski, Alexei G.

1997-08-01

A new method of dental introscopy in-vitro is suggested by the authors. This method implies the usage of longitudinal tomography techniques and is characterized by non-invasive and non-harmful diagnostics features, as well as interactive regime of image reconstruction which lets an operator (doctor) to control the diagnostics process in real time. He-Ne laser emission is used for obtaining of the projections. By the means of longitudinal tomography, images of different sections of an object (tooth) can be reconstructed. An experiment was held by the authors in which 100 projections of a tooth (premolar) were obtained and images of 10 different sections were reconstructed. These images were later compared to real sections of the tooth. This experiment proved that optical longitudinal tomography can be successfully used for dental introscopy. Authors claim that optical tomographic methods can be used for diagnostics of other biological objects as well. Such objects are characterized by spatial geometrical anisotropy (tubular bones, phalanxes of fingers, penis, etc.). It is especially promising to use this method for children's dentistry. the authors discuss some features of the data acquisition system for optical longitudinal tomography. Reconstruction algorithms are described. The results of experimental reconstruction are presented and advantages of this diagnostics method are discussed.

A review of novel optical imaging strategies of the stroke pathology and stem cell therapy in stroke

PubMed Central

Aswendt, Markus; Adamczak, Joanna; Tennstaedt, Annette

2014-01-01

Transplanted stem cells can induce and enhance functional recovery in experimental stroke. Invasive analysis has been extensively used to provide detailed cellular and molecular characterization of the stroke pathology and engrafted stem cells. But post mortem analysis is not appropriate to reveal the time scale of the dynamic interplay between the cell graft, the ischemic lesion and the endogenous repair mechanisms. This review describes non-invasive imaging techniques which have been developed to provide complementary in vivo information. Recent advances were made in analyzing simultaneously different aspects of the cell graft (e.g., number of cells, viability state, and cell fate), the ischemic lesion (e.g., blood–brain-barrier consistency, hypoxic, and necrotic areas) and the neuronal and vascular network. We focus on optical methods, which permit simple animal preparation, repetitive experimental conditions, relatively medium-cost instrumentation and are performed under mild anesthesia, thus nearly under physiological conditions. A selection of recent examples of optical intrinsic imaging, fluorescence imaging and bioluminescence imaging to characterize the stroke pathology and engrafted stem cells are discussed. Special attention is paid to novel optimal reporter genes/probes for genetic labeling and tracking of stem cells and appropriate transgenic animal models. Requirements, advantages and limitations of these imaging platforms are critically discussed and placed into the context of other non-invasive techniques, e.g., magnetic resonance imaging and positron emission tomography, which can be joined with optical imaging in multimodal approaches. PMID:25177269

Application of optical coherence tomography for noninvasive blood glucose monitoring during hyperglycemia

NASA Astrophysics Data System (ADS)

Larin, Kirill V.; Ashitkov, Taras V.; Motamedi, Massoud; Esenaliev, Rinat O.

2003-10-01

Approximately 14 million people in the USA and more than 140 million people worldwide suffer from Diabetes Mellitus. The current glucose sensing technique involves a finger puncture several times a day to obtain a droplet of blood for chemical analysis. Recently we proposed to use optical coherence tomography (OCT) for continuous noninvasive blood glucose sensing through skin. In this paper we tested the OCT technique for noninvasive monitoring of blood glucose concentration in lip tissue of New Zealand rabbits and Yucatan micropigs during glucose clamping experiments. Obtained results show good agreement with results obtained in skin studies, good correlation of changes in the OCT signal slope measured at the depth of 250 to 500 μm with changes in blood glucose concentration, and higher stability of the OCT data points than that obtained from skin.

A fast reconstruction algorithm for fluorescence optical diffusion tomography based on preiteration.

PubMed

Song, Xiaolei; Xiong, Xiaoyun; Bai, Jing

2007-01-01

Fluorescence optical diffusion tomography in the near-infrared (NIR) bandwidth is considered to be one of the most promising ways for noninvasive molecular-based imaging. Many reconstructive approaches to it utilize iterative methods for data inversion. However, they are time-consuming and they are far from meeting the real-time imaging demands. In this work, a fast preiteration algorithm based on the generalized inverse matrix is proposed. This method needs only one step of matrix-vector multiplication online, by pushing the iteration process to be executed offline. In the preiteration process, the second-order iterative format is employed to exponentially accelerate the convergence. Simulations based on an analytical diffusion model show that the distribution of fluorescent yield can be well estimated by this algorithm and the reconstructed speed is remarkably increased.

OCT investigation of dental lesions

NASA Astrophysics Data System (ADS)

Osiac, Eugen; Popescu, Sanda Mihaela; Scrieciu, Monica; Mercuţ, Rǎzvan; Mercuţ, Veronica; Vǎtu, Mihaela

2018-03-01

There are several important non carious lesions affecting the tooth structure, lesions which may be classified into four clinical forms of dental wear: abfraction, erosion, attrition and abrasion, and different types of root resorption. Search for new, non-invasive and fast methods able to detect and describe such injuries is of utmost importance. Optical coherence tomography (OCT) proved itself as an appropriate investigation method for several medical fields including ophthalmology, dermatology, cardiology etc. Our study reveals OCT preliminary investigations as a promising tool for detecting and evaluating of the mentioned lesions.

Apparatus and method for rapid detection of explosives residue from the deflagration signature thereof

DOEpatents

Funsten, Herbert O.; McComas, David J.

1997-01-01

Apparatus and method for rapid detection of explosives residue from the deflagration signature thereof. A property inherent to most explosives is their stickiness, resulting in a strong tendency of explosive particulate to contaminate the environment of a bulk explosive. An apparatus for collection of residue particulate, burning the collected particulate, and measurement of the optical emission produced thereby is described. The present invention can be utilized for real-time screening of personnel, cars, packages, suspected devices, etc., and provides an inexpensive, portable, and noninvasive means for detecting explosives.

Noninvasive clinical assessment of port-wine stain birthmarks using current and future optical imaging technology: A review

PubMed Central

Sharif, S.A.; Taydas, E.; Mazhar, A.; Rahimian, R.; Kelly, K.M.; Choi, B.; Durkin, A.J.

2012-01-01

Port wine stain (PWS) birthmarks are one class of benign congenital vascular malformation. Laser therapy is the most successful treatment modality of PWS. Unfortunately, this approach has limited efficacy, with only 10% of patients experiencing complete blanching of the PWS. To address this problem, several research groups have developed technologies and methods designed to study treatment outcome and improve treatment efficacy. This paper reviews seven optical imaging techniques currently in use or under development to assess treatment efficacy, focusing on: Reflectance spectrophotometers/tristimulus colorimeters, Laser Doppler flowmetry (LDF) and Laser Doppler imaging (LDI), Cross-polarized diffuse reflectance color imaging system (CDR), Reflectance Confocal Microscopy (RCM), Optical Coherence Tomography (OCT), Spatial Frequency Domain Imaging (SFDI), and Laser Speckle Imaging (LSI). PMID:22804872

Combined spectral-domain optical coherence tomography and hyperspectral imaging applied for tissue analysis: Preliminary results

NASA Astrophysics Data System (ADS)

Dontu, S.; Miclos, S.; Savastru, D.; Tautan, M.

2017-09-01

In recent years many optoelectronic techniques have been developed for improvement and the development of devices for tissue analysis. Spectral-Domain Optical Coherence Tomography (SD-OCT) is a new medical interferometric imaging modality that provides depth resolved tissue structure information with resolution in the μm range. However, SD-OCT has its own limitations and cannot offer the biochemical information of the tissue. These data can be obtained with hyperspectral imaging, a non-invasive, sensitive and real time technique. In the present study we have combined Spectral-Domain Optical Coherence Tomography (SD-OCT) with Hyperspectral imaging (HSI) for tissue analysis. The Spectral-Domain Optical Coherence Tomography (SD-OCT) and Hyperspectral imaging (HSI) are two methods that have demonstrated significant potential in this context. Preliminary results using different tissue have highlighted the capabilities of this technique of combinations.

Diffuse reflectance spectroscopy of liver tissue

NASA Astrophysics Data System (ADS)

Reistad, Nina; Nilsson, Jan; Vilhelmsson Timmermand, Oskar; Sturesson, Christian; Andersson-Engels, Stefan

2015-06-01

Diffuse reflectance spectroscopy (DRS) with a fiber-optic contact probe is a cost-effective, rapid, and non-invasive optical method used to extract diagnosis information of tissue. By combining commercially available VIS- and NIR-spectrometers with various fiber-optic contact-probes, we have access to the full wavelength range from around 400 to 1600 nm. Using this flexible and portable spectroscopy system, we have acquired ex-vivo DRS-spectra from murine, porcine, and human liver tissue. For extracting the tissue optical properties from the measured spectra, we have employed and compared predictions from two models for light propagation in tissue, diffusion theory model (DT) and Monte Carlo simulations (MC). The focus in this work is on the capacity of this DRS-technique in discriminating metastatic tumor tissue from normal liver tissue as well as in assessing and characterizing damage to non-malignant liver tissue induced by preoperative chemotherapy for colorectal liver metastases.

In vivo optical coherence tomography of stimulus-evoked intrinsic optical signals in mouse retinas

NASA Astrophysics Data System (ADS)

Wang, Benquan; Lu, Yiming; Yao, Xincheng

2016-09-01

Intrinsic optical signal (IOS) imaging promises a noninvasive method for advanced study and diagnosis of eye diseases. Before pursuing clinical applications, it is essential to understand anatomic and physiological sources of retinal IOSs and to establish the relationship between IOS distortions and eye diseases. The purpose of this study was designed to demonstrate the feasibility of in vivo IOS imaging of mouse models. A high spatiotemporal resolution spectral domain optical coherence tomography (SD-OCT) was employed for depth-resolved retinal imaging. A custom-designed animal holder equipped with ear bar and bite bar was used to minimize eye movements. Dynamic OCT imaging revealed rapid IOS from the photoreceptor's outer segment immediately after the stimulation delivery, and slow IOS changes were observed from inner retinal layers. Comparative photoreceptor IOS and electroretinography recordings suggested that the fast photoreceptor IOS may be attributed to the early stage of phototransduction before the hyperpolarization of retinal photoreceptor.

Non-invasive red light optogenetic pacing and optical coherence microscopy (OCM) imaging for drosophila melanogaster (Conference Presentation)

NASA Astrophysics Data System (ADS)

Men, Jing; Li, Airong; Jerwick, Jason; Tanzi, Rudolph E.; Zhou, Chao

2017-02-01

Cardiac pacing could be a powerful tool for investigating mammalian cardiac electrical conduction systems as well as for treatment of certain cardiac pathologies. However, traditional electrical pacing using pacemaker requires an invasive surgical procedure. Electrical currents from the implanted electrodes can also cause damage to heart tissue, further restricting its utility. Optogenetic pacing has been developed as a promising, non-invasive alternative to electrical stimulation for controlling animal heart rhythms. It induces heart contractions by shining pulsed light on transgene-generated microbial opsins, which in turn activate the light gated ion channels in animal hearts. However, commonly used opsins in optogenetic pacing, such as channelrhodopsin-2 (ChR2), require short light wavelength stimulation (475 nm), which is strongly absorbed and scattered by tissue. Here, we performed optogenetic pacing by expression of recently engineered red-shifted microbial opsins, ReaChR and CsChrimson, in a well-established animal model, Drosophila melanogaster, using the 617 nm stimulation light pulses. The OCM technique enables non-invasive optical imaging of animal hearts with high speed and ultrahigh axial and transverse resolutions. We integrated a customized OCM system with the optical stimulation system to monitor the optogenetic pacing noninvasively. The use of red-sifted opsins enabled deeper penetration of simulating light at lower power, which is promising for applications of optogenetic pacing in mammalian cardiac pathology studies or clinical treatments in the future.

Detecting cell death with optical coherence tomography and envelope statistics

NASA Astrophysics Data System (ADS)

Farhat, Golnaz; Yang, Victor X. D.; Czarnota, Gregory J.; Kolios, Michael C.

2011-02-01

Currently no standard clinical or preclinical noninvasive method exists to monitor cell death based on morphological changes at the cellular level. In our past work we have demonstrated that quantitative high frequency ultrasound imaging can detect cell death in vitro and in vivo. In this study we apply quantitative methods previously used with high frequency ultrasound to optical coherence tomography (OCT) to detect cell death. The ultimate goal of this work is to use these methods for optically-based clinical and preclinical cancer treatment monitoring. Optical coherence tomography data were acquired from acute myeloid leukemia cells undergoing three modes of cell death. Significant increases in integrated backscatter were observed for cells undergoing apoptosis and mitotic arrest, while necrotic cells induced a decrease. These changes appear to be linked to structural changes observed in histology obtained from the cell samples. Signal envelope statistics were analyzed from fittings of the generalized gamma distribution to histograms of envelope intensities. The parameters from this distribution demonstrated sensitivities to morphological changes in the cell samples. These results indicate that OCT integrated backscatter and first order envelope statistics can be used to detect and potentially differentiate between modes of cell death in vitro.

Effect of cantilever geometry on the optical lever sensitivities and thermal noise method of the atomic force microscope.

PubMed

Sader, John E; Lu, Jianing; Mulvaney, Paul

2014-11-01

Calibration of the optical lever sensitivities of atomic force microscope (AFM) cantilevers is especially important for determining the force in AFM measurements. These sensitivities depend critically on the cantilever mode used and are known to differ for static and dynamic measurements. Here, we calculate the ratio of the dynamic and static sensitivities for several common AFM cantilevers, whose shapes vary considerably, and experimentally verify these results. The dynamic-to-static optical lever sensitivity ratio is found to range from 1.09 to 1.41 for the cantilevers studied - in stark contrast to the constant value of 1.09 used widely in current calibration studies. This analysis shows that accuracy of the thermal noise method for the static spring constant is strongly dependent on cantilever geometry - neglect of these dynamic-to-static factors can induce errors exceeding 100%. We also discuss a simple experimental approach to non-invasively and simultaneously determine the dynamic and static spring constants and optical lever sensitivities of cantilevers of arbitrary shape, which is applicable to all AFM platforms that have the thermal noise method for spring constant calibration.

Development and application of noninvasive technology for study of combustion in a combustion chamber of gas turbine engine

NASA Astrophysics Data System (ADS)

Inozemtsev, A. A.; Sazhenkov, A. N.; Tsatiashvili, V. V.; Abramchuk, T. V.; Shipigusev, V. A.; Andreeva, T. P.; Gumerov, A. R.; Ilyin, A. N.; Gubaidullin, I. T.

2015-05-01

The paper formulates the issue of development of experimental base with noninvasive optical-electronic tools for control of combustion in a combustion chamber of gas turbine engine. The design and specifications of a pilot sample of optronic system are explained; this noninvasive system was created in the framework of project of development of main critical technologies for designing of aviation gas turbine engine PD-14. The testbench run data are presented.

Validation of Noninvasive MOEMS-Assisted Measurement System Based on CCD Sensor for Radial Pulse Analysis

PubMed Central

Malinauskas, Karolis; Palevicius, Paulius; Ragulskis, Minvydas; Ostasevicius, Vytautas; Dauksevicius, Rolanas

2013-01-01

Examination of wrist radial pulse is a noninvasive diagnostic method, which occupies a very important position in Traditional Chinese Medicine. It is based on manual palpation and therefore relies largely on the practitioner′s subjective technical skills and judgment. Consequently, it lacks reliability and consistency, which limits practical applications in clinical medicine. Thus, quantifiable characterization of the wrist pulse diagnosis method is a prerequisite for its further development and widespread use. This paper reports application of a noninvasive CCD sensor-based hybrid measurement system for radial pulse signal analysis. First, artery wall deformations caused by the blood flow are calibrated with a laser triangulation displacement sensor, following by the measurement of the deformations with projection moiré method. Different input pressures and fluids of various viscosities are used in the assembled artificial blood flow system in order to test the performance of laser triangulation technique with detection sensitivity enhancement through microfabricated retroreflective optical element placed on a synthetic vascular graft. Subsequently, the applicability of double-exposure whole-field projection moiré technique for registration of blood flow pulses is considered: a computational model and representative example are provided, followed by in vitro experiment performed on a vascular graft with artificial skin atop, which validates the suitability of the technique for characterization of skin surface deformations caused by the radial pulsation. PMID:23609803

Validation of noninvasive MOEMS-assisted measurement system based on CCD sensor for radial pulse analysis.

PubMed

Malinauskas, Karolis; Palevicius, Paulius; Ragulskis, Minvydas; Ostasevicius, Vytautas; Dauksevicius, Rolanas

2013-04-22

Examination of wrist radial pulse is a noninvasive diagnostic method, which occupies a very important position in Traditional Chinese Medicine. It is based on manual palpation and therefore relies largely on the practitioner's subjective technical skills and judgment. Consequently, it lacks reliability and consistency, which limits practical applications in clinical medicine. Thus, quantifiable characterization of the wrist pulse diagnosis method is a prerequisite for its further development and widespread use. This paper reports application of a noninvasive CCD sensor-based hybrid measurement system for radial pulse signal analysis. First, artery wall deformations caused by the blood flow are calibrated with a laser triangulation displacement sensor, following by the measurement of the deformations with projection moiré method. Different input pressures and fluids of various viscosities are used in the assembled artificial blood flow system in order to test the performance of laser triangulation technique with detection sensitivity enhancement through microfabricated retroreflective optical element placed on a synthetic vascular graft. Subsequently, the applicability of double-exposure whole-field projection moiré technique for registration of blood flow pulses is considered: a computational model and representative example are provided, followed by in vitro experiment performed on a vascular graft with artificial skin atop, which validates the suitability of the technique for characterization of skin surface deformations caused by the radial pulsation.

Non-invasive imaging of zebrafish with spinal deformities using optical coherence tomography: a preliminary study

NASA Astrophysics Data System (ADS)

Bernstein, Liane; Beaudette, Kathy; Patten, Kessen; Beaulieu-Ouellet, Émilie; Strupler, Mathias; Moldovan, Florina; Boudoux, Caroline

2013-03-01

A zebrafish model has recently been introduced to study various genetic mutations that could lead to spinal deformities such as scoliosis. However, current imaging techniques make it difficult to perform longitudinal studies of this condition in zebrafish, especially in the early stages of development. The goal of this project is to determine whether optical coherence tomography (OCT) is a viable non-invasive method to image zebrafish exhibiting spinal deformities. Images of both live and fixed malformed zebrafish (5 to 21 days postfertilization) as well as wild-type fish (5 to 29 days postfertilization) were acquired non-invasively using a commercial SD-OCT system, with a laser source centered at 930nm (λ=100nm), permitting axial and lateral resolutions of 7 and 8μm respectively. Using two-dimensional images and three-dimensional reconstructions, it was possible to identify the malformed notochord as well as deformities in other major organs at different stages of formation. Visualization of the notochord was facilitated with the development of a segmentation algorithm. OCT images were compared to HE histological sections and images obtained by calcein staining. Because of the possibility of performing longitudinal studies on a same fish and reducing image processing time as compared with staining techniques and histology, the use of OCT could facilitate phenotypic characterization in studying genetic factors leading to spinal deformities in zebrafish and could eventually contribute to the identification of the genetic causes of spinal deformities such as scoliosis.

Nonthermal ablation with microbubble-enhanced focused ultrasound close to the optic tract without affecting nerve function

PubMed Central

McDannold, Nathan; Zhang, Yong-Zhi; Power, Chanikarn; Jolesz, Ferenc; Vykhodtseva, Natalia

2014-01-01

Object Tumors at the skull base are challenging for both resection and radiosurgery given the presence of critical adjacent structures, such as cranial nerves, blood vessels, and brainstem. Magnetic resonance imaging–guided thermal ablation via laser or other methods has been evaluated as a minimally invasive alternative to these techniques in the brain. Focused ultrasound (FUS) offers a noninvasive method of thermal ablation; however, skull heating limits currently available technology to ablation at regions distant from the skull bone. Here, the authors evaluated a method that circumvents this problem by combining the FUS exposures with injected microbubble-based ultrasound contrast agent. These microbubbles concentrate the ultrasound-induced effects on the vasculature, enabling an ablation method that does not cause significant heating of the brain or skull. Methods In 29 rats, a 525-kHz FUS transducer was used to ablate tissue structures at the skull base that were centered on or adjacent to the optic tract or chiasm. Low-intensity, low-duty-cycle ultrasound exposures (sonications) were applied for 5 minutes after intravenous injection of an ultrasound contrast agent (Definity, Lantheus Medical Imaging Inc.). Using histological analysis and visual evoked potential (VEP) measurements, the authors determined whether structural or functional damage was induced in the optic tract or chiasm. Results Overall, while the sonications produced a well-defined lesion in the gray matter targets, the adjacent tract and chiasm had comparatively little or no damage. No significant changes (p > 0.05) were found in the magnitude or latency of the VEP recordings, either immediately after sonication or at later times up to 4 weeks after sonication, and no delayed effects were evident in the histological features of the optic nerve and retina. Conclusions This technique, which selectively targets the intravascular microbubbles, appears to be a promising method of noninvasively producing sharply demarcated lesions in deep brain structures while preserving function in adjacent nerves. Because of low vascularity—and thus a low microbubble concentration—some large white matter tracts appear to have some natural resistance to this type of ablation compared with gray matter. While future work is needed to develop methods of monitoring the procedure and establishing its safety at deep brain targets, the technique does appear to be a potential solution that allows FUS ablation of deep brain targets while sparing adjacent nerve structures. PMID:24010975

Noninvasive in vivo optical characterization of blood flow and oxygen consumption in the superficial plexus of skin

NASA Astrophysics Data System (ADS)

Liasi, Faezeh Talebi; Samatham, Ravikant; Jacques, Steven L.

2017-11-01

Assessing the metabolic activity of a tissue, whether normal, damaged, aged, or pathologic, is useful for diagnosis and evaluating the effects of drugs. This report describes a handheld optical fiber probe that contacts the skin, applies pressure to blanch the superficial vascular plexus of the skin, then releases the pressure to allow refill of the plexus. The optical probe uses white light spectroscopy to record the time dynamics of blanching and refilling. The magnitude and dynamics of changes in blood content and hemoglobin oxygen saturation yield an estimate of the oxygen consumption rate (OCR) in units of attomoles per cell per second. The average value of OCR on nine forearm sites on five subjects was 10±5 (amol/cell/s). This low-cost, portable, rapid, noninvasive optical probe can characterize the OCR of a skin site to assess the metabolic activity of the epidermis or a superficial lesion.

Noninvasive spectroscopic diagnosis of superficial ocular lesions and corneal infections

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mourant, J.R.; Bigio, I.J.; Johnson, T.

The potential of a rapid noninvasive diagnostic system to detect tissue abnormalities on the surface of the eye has been investigated. The optical scatter signal from lesions and normal areas on the conjunctival sclera of the human eye were measured in vivo. It is possible to distinguish nonpigmented pingueculas from other lesions. The ability of the system to detect malignancies could not be tested because none of the measured and biopsied lesions were malignant. Optical scatter and fluorescence spectra of bacterial and fungal suspensions, and corneal irritations were also collected. Both scattering and fluorescence show potential for diagnosing corneal infections.

Deep tissue optical focusing and optogenetic modulation with time-reversed ultrasonically encoded light

PubMed Central

Ruan, Haowen; Brake, Joshua; Robinson, J. Elliott; Liu, Yan; Jang, Mooseok; Xiao, Cheng; Zhou, Chunyi; Gradinaru, Viviana; Yang, Changhuei

2017-01-01

Noninvasive light focusing deep inside living biological tissue has long been a goal in biomedical optics. However, the optical scattering of biological tissue prevents conventional optical systems from tightly focusing visible light beyond several hundred micrometers. The recently developed wavefront shaping technique time-reversed ultrasonically encoded (TRUE) focusing enables noninvasive light delivery to targeted locations beyond the optical diffusion limit. However, until now, TRUE focusing has only been demonstrated inside nonliving tissue samples. We present the first example of TRUE focusing in 2-mm-thick living brain tissue and demonstrate its application for optogenetic modulation of neural activity in 800-μm-thick acute mouse brain slices at a wavelength of 532 nm. We found that TRUE focusing enabled precise control of neuron firing and increased the spatial resolution of neuronal excitation fourfold when compared to conventional lens focusing. This work is an important step in the application of TRUE focusing for practical biomedical uses. PMID:29226248

Application of optical coherence tomography and high-frequency ultrasound imaging during noninvasive laser vasectomy

NASA Astrophysics Data System (ADS)

Cilip, Christopher M.; Allaf, Mohamad E.; Fried, Nathaniel M.

2012-04-01

A noninvasive approach to vasectomy may eliminate male fear of complications related to surgery and increase its acceptance. Noninvasive laser thermal occlusion of the canine vas deferens has recently been reported. Optical coherence tomography (OCT) and high-frequency ultrasound (HFUS) are compared for monitoring laser thermal coagulation of the vas in an acute canine model. Bilateral noninvasive laser coagulation of the vas was performed in six dogs (n=12 vasa) using a Ytterbium fiber laser wavelength of 1075 nm, incident power of 9.0 W, pulse duration of 500 ms, pulse rate of 1 Hz, and 3-mm-diameter spot. Cryogen spray cooling was used to prevent skin burns during the procedure. An OCT system with endoscopic probe and a HFUS system with 20-MHz transducer were used to image the vas immediately before and after the procedure. Vasa were then excised and processed for gross and histologic analysis for comparison with OCT and HFUS images. OCT provided high-resolution, superficial imaging of the compressed vas within the vas ring clamp, while HFUS provided deeper imaging of the vas held manually in the scrotal fold. Both OCT and high HFUS are promising imaging modalities for real-time confirmation of vas occlusion during noninvasive laser vasectomy.

Optical coherence tomography vs. high-frequency ultrasound during noninvasive laser coagulation of the canine vas deferens

NASA Astrophysics Data System (ADS)

Cilip, Christopher M.; Allaf, Mohamad E.; Fried, Nathaniel M.

2012-02-01

A noninvasive approach to vasectomy may eliminate male fear of complications related to surgery and increase its acceptance. Noninvasive laser thermal occlusion of the canine vas deferens has recently been reported. In this study, optical coherence tomography (OCT) and high-frequency ultrasound (HFUS) are compared for monitoring laser thermal coagulation of the vas in an acute canine model. Bilateral noninvasive laser coagulation of the vas was performed in 6 dogs (n=12 vasa) using a Ytterbium fiber laser wavelength of 1075 nm, incident power of 9.0 W, pulse duration of 500 ms, pulse rate of 1 Hz, and 3-mm-diameter spot. Cryogen spray cooling was used to prevent skin burns during the procedure. An OCT system with endoscopic probe and a HFUS system with 20-MHz transducer were used to image the vas immediately before and after the procedure. Vasa were then excised and processed for gross and histologic analysis for comparison with OCT and HFUS images. OCT provided high-resolution, superficial imaging of the compressed vas within the vas ring clamp, while HFUS provided deeper imaging of the vas held manually in the scrotal fold. Both OCT and high HFUS are promising imaging modalities for real-time confirmation of vas occlusion during noninvasive laser vasectomy.

Super-resolution structured illumination in optically thick specimens without fluorescent tagging

NASA Astrophysics Data System (ADS)

Hoffman, Zachary R.; DiMarzio, Charles A.

2017-11-01

This research extends the work of Hoffman et al. to provide both sectioning and super-resolution using random patterns within thick specimens. Two methods of processing structured illumination in reflectance have been developed without the need for a priori knowledge of either the optical system or the modulation patterns. We explore the use of two deconvolution algorithms that assume either Gaussian or sparse priors. This paper will show that while both methods accomplish their intended objective, the sparse priors method provides superior resolution and contrast against all tested targets, providing anywhere from ˜1.6× to ˜2× resolution enhancement. The methods developed here can reasonably be implemented to work without a priori knowledge about the patterns or point spread function. Further, all experiments are run using an incoherent light source, unknown random modulation patterns, and without the use of fluorescent tagging. These additional modifications are challenging, but the generalization of these methods makes them prime candidates for clinical application, providing super-resolved noninvasive sectioning in vivo.

Electro-optical Probing Of Terahertz Integrated Circuits

NASA Technical Reports Server (NTRS)

Bhasin, K. B.; Romanofsky, R.; Whitaker, J. F.; Valdmanis, J. A.; Mourou, G.; Jackson, T. A.

1990-01-01

Electro-optical probe developed to perform noncontact, nondestructive, and relatively noninvasive measurements of electric fields over broad spectrum at millimeter and shorter wavelengths in integrated circuits. Manipulated with conventional intregrated-circuit-wafer-probing equipment and operated without any special preparation of integrated circuits. Tip of probe small electro-optical crystal serving as proximity electric-field sensor.

A portable system for noninvasive assessment of advanced glycation end-products using skin fluorescence and reflectance spectrum

NASA Astrophysics Data System (ADS)

Wang, Y. K.; Zhu, L.; Zhang, L.; Zhang, G.; Liu, Y.; Wang, A.

2012-07-01

An optical system has been developed for noninvasive assessment of skin advanced glycation end-products (AGEs). The system comprises mainly a high-power ultraviolet light emitting diode (LED) as an excitation source, an LED array for the reflectance measurement, a trifurcated fiber-optic probe for light transmitting and receiving, and a compact spectrometer for light detecting. Both skin fluorescence of a subject and the reflectance spectrum of the same site can be obtained in a single measurement with the system. Demonstrative measurements with the system have been conducted. Results indicate that the measured reflectance spectrum can be used to compensate for the distortion of AGEs fluorescence, which is caused by skin absorption and scattering. The system is noninvasive, portable, easy to operate, and has potential applications for clinical diagnosis of AGE-related diseases, especially diabetes mellitus.

A rapid and non-invasive method for measuring the peak positive pressure of HIFU fields by a laser beam.

PubMed

Wang, Hua; Zeng, Deping; Chen, Ziguang; Yang, Zengtao

2017-04-12

Based on the acousto-optic interaction, we propose a laser deflection method for rapidly, non-invasively and quantitatively measuring the peak positive pressure of HIFU fields. In the characterization of HIFU fields, the effect of nonlinear propagation is considered. The relation between the laser deflection length and the peak positive pressure is derived. Then the laser deflection method is assessed by comparing it with the hydrophone method. The experimental results show that the peak positive pressure measured by laser deflection method is little higher than that obtained by the hydrophone, confirming that they are in reasonable agreement. Considering that the peak pressure measured by hydrophones is always underestimated, the laser deflection method is assumed to be more accurate than the hydrophone method due to the absence of the errors in hydrophone spatial-averaging measurement and the influence of waveform distortion on hydrophone corrections. Moreover, noting that the Lorentz formula still remains applicable to high-pressure environments, the laser deflection method exhibits a great potential for measuring HIFU field under high-pressure amplitude. Additionally, the laser deflection method provides a rapid way for measuring the peak positive pressure, without the scan time, which is required by the hydrophones.

Silicon nanowires: where mechanics and optics meet at the nanoscale.

PubMed

Ramos, Daniel; Gil-Santos, Eduardo; Malvar, Oscar; Llorens, Jose M; Pini, Valerio; San Paulo, Alvaro; Calleja, Montserrat; Tamayo, Javier

2013-12-06

Mechanical transducers based on nanowires promise revolutionary advances in biological sensing and force microscopy/spectroscopy. A crucial step is the development of simple and non-invasive techniques able to detect displacements with subpicometer sensitivity per unit bandwidth. Here, we design suspended tapered silicon nanowires supporting a range of optical resonances that confine and efficiently scatter light in the visible range. Then, we develop an optical method for efficiently coupling the evanescent field to the regular interference pattern generated by an incoming laser beam and the reflected beam from the substrate underneath the nanowire. This optomechanical coupling is here applied to measure the displacement of 50 nm wide nanowires with sensitivity on the verge of 1 fm/Hz(1/2) at room temperature with a simple laser interferometry set-up. This method opens the door to the measurement of the Brownian motion of ultrashort nanowires for the detection of single biomolecular recognition events in liquids, and single molecule spectroscopy in vacuum.

Non-invasive In Vivo Fluorescence Optical Imaging of Inflammatory MMP Activity Using an Activatable Fluorescent Imaging Agent.

PubMed

Schwenck, Johannes; Maier, Florian C; Kneilling, Manfred; Wiehr, Stefan; Fuchs, Kerstin

2017-05-08

This paper describes a non-invasive method for imaging matrix metalloproteinases (MMP)-activity by an activatable fluorescent probe, via in vivo fluorescence optical imaging (OI), in two different mouse models of inflammation: a rheumatoid arthritis (RA) and a contact hypersensitivity reaction (CHR) model. Light with a wavelength in the near infrared (NIR) window (650 - 950 nm) allows a deeper tissue penetration and minimal signal absorption compared to wavelengths below 650 nm. The major advantages using fluorescence OI is that it is cheap, fast and easy to implement in different animal models. Activatable fluorescent probes are optically silent in their inactivated states, but become highly fluorescent when activated by a protease. Activated MMPs lead to tissue destruction and play an important role for disease progression in delayed-type hypersensitivity reactions (DTHRs) such as RA and CHR. Furthermore, MMPs are the key proteases for cartilage and bone degradation and are induced by macrophages, fibroblasts and chondrocytes in response to pro-inflammatory cytokines. Here we use a probe that is activated by the key MMPs like MMP-2, -3, -9 and -13 and describe an imaging protocol for near infrared fluorescence OI of MMP activity in RA and control mice 6 days after disease induction as well as in mice with acute (1x challenge) and chronic (5x challenge) CHR on the right ear compared to healthy ears.

Non-invasive optical assessment of viscosity of middle ear effusions in otitis media.

PubMed

Monroy, Guillermo L; Pande, Paritosh; Shelton, Ryan L; Nolan, Ryan M; Spillman, Darold R; Porter, Ryan G; Novak, Michael A; Boppart, Stephen A

2017-03-01

Eustachian tube dysfunction can cause fluid to collect within the middle ear cavity and form a middle ear effusion (MEE). MEEs can persist for weeks or months and cause hearing loss as well as speech and learning delays in young children. The ability of a physician to accurately identify and characterize the middle ear for signs of fluid and/or infection is crucial to provide the most appropriate treatment for the patient. Currently, middle ear infections are assessed with otoscopy, which provides limited and only qualitative diagnostic information. In this study, we propose a method utilizing cross-sectional depth-resolved optical coherence tomography to noninvasively measure the diffusion coefficient and viscosity of colloid suspensions, such as a MEE. Experimental validation of the proposed technique on simulated MEE phantoms with varying viscosity and particulate characteristics is presented, along with some preliminary results from in vivo and ex vivo samples of human MEEs. In vivo Optical Coherence Tomography (OCT) image of a human tympanic membrane and Middle Ear Effusion (MEE) (top), with a CCD image of the tympanic membrane surface (inset). Below is the corresponding time-lapse M-mode OCT data acquired along the white dotted line over time, which can be analyzed to determine the Stokes-Einstein diffusion coefficient of the effusion. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Remote Skin Tissue Diagnostics In Vivo By Fiber Optic Evanescent Wave Fourier Transform Infrared (FEW-FTIR) Spectroscopy

NASA Astrophysics Data System (ADS)

Kolyakov, Sergei; Afanasyeva, Natalia; Bruch, Reinhard; Afanasyeva, Natalia

1998-05-01

The new method of fiber optical evanescent wave Fourier transform infrared (FEW-FTIR) spectroscopy has been applied to the diagnostics of normal skin tissue, as well as precancerous and cancerous conditions. The FEW-FTIR technique is nondestructive and sensitive to changes of vibrational spectra in the IR region, without heating and damaging human and animal skin tissue. Therefore this method and technique is an ideal diagnostic tool for tumor and cancer characterization at an early stage of development on a molecular level. The application of fiber optic technology in the middle infrared (MIR) region is relatively inexpensive and can be adapted easily to any commercially available tabletop FTIR spectrometers. This method of diagnostics is fast (several seconds), and can be applied to many fields. Noninvasive medical diagnostics of skin cancer and other skin diseases in vivo, ex vivo, and in vitro allow for the development of convenient, remote clinical applications in dermatology and related fields. The spectral variations from normal to pathological skin tissue and environmental influence on skin have been measured.

Noninvasive optical diagnosis of low back pain with the aid of Chinese cupping procedure

NASA Astrophysics Data System (ADS)

Li, Nanxi; Li, Ting

2018-02-01

Low back pain (LBP) is a complex disease that can be cause by a variety of reasons. Now LBP has become a very common and severe disease among kinds of occupational groups with showing a younger trend. The traditional diagnosis relies on complicated imaging modalities and other dangerous and invasive methods. Noninvasive near-infrared spectroscopy (NIRS) is noninvasive and convenient, and has been successful used in point-of-care diagnosis. Here, we attempt to explore NIRS's application in in low back pain diagnosis and the effect of aid-use of Chinese cupping procedure. 13 LBP patients and 13 healthy subjects participated in NIRS measurements of concentrations of oxy- and deoxy-hemoglobins (Δ[HbO2] and Δ[Hb]) at the middle of the lumbar spine. It was showed that there was significant differences (p < 0.001) between healthy subjects and LBP patients after cupping procedure, while insignificant before cupping. Moreover, it was found that healthy subjects showed stronger responses to cupping procedure than LBP patients, with prominently higher concentration of Δ[HbO2] and Δ[Hb]. It indicates the potential of NIRS in noninvasive, measurable and straightforward monitoring/therapeutic effect evaluation of LBP with bedside and point-of-care monitoring capability.

Functional imaging and assessment of the glucose diffusion rate in epithelial tissues in optical coherence tomography

NASA Astrophysics Data System (ADS)

Larin, K. V.; Tuchin, V. V.

2008-06-01

Functional imaging, monitoring and quantitative description of glucose diffusion in epithelial and underlying stromal tissues in vivo and controlling of the optical properties of tissues are extremely important for many biomedical applications including the development of noninvasive or minimally invasive glucose sensors as well as for therapy and diagnostics of various diseases, such as cancer, diabetic retinopathy, and glaucoma. Recent progress in the development of a noninvasive molecular diffusion biosensor based on optical coherence tomography (OCT) is described. The diffusion of glucose was studied in several epithelial tissues both in vitro and in vivo. Because OCT provides depth-resolved imaging of tissues with high in-depth resolution, the glucose diffusion is described not only as a function of time but also as a function of depth.

Kinetics of T-cell receptor-dependent antigen recognition determined in vivo by multi-spectral normalized epifluorescence laser scanning

NASA Astrophysics Data System (ADS)

Favicchio, Rosy; Zacharakis, Giannis; Oikonomaki, Katerina; Zacharopoulos, Athanasios; Mamalaki, Clio; Ripoll, Jorge

2012-07-01

Detection of multiple fluorophores in conditions of low signal represents a limiting factor for the application of in vivo optical imaging techniques in immunology where fluorescent labels report for different functional characteristics. A noninvasive in vivo Multi-Spectral Normalized Epifluorescence Laser scanning (M-SNELS) method was developed for the simultaneous and quantitative detection of multiple fluorophores in low signal to noise ratios and used to follow T-cell activation and clonal expansion. Colocalized DsRed- and GFP-labeled T cells were followed in tandem during the mounting of an immune response. Spectral unmixing was used to distinguish the overlapping fluorescent emissions representative of the two distinct cell populations and longitudinal data reported the discrete pattern of antigen-driven proliferation. Retrieved values were validated both in vitro and in vivo with flow cytometry and significant correlation between all methodologies was achieved. Noninvasive M-SNELS successfully quantified two colocalized fluorescent populations and provides a valid alternative imaging approach to traditional invasive methods for detecting T cell dynamics.

Noninvasive identification of bladder cancer with sub-surface backscattered light

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bigio, I.J.; Mourant, J.R.; Boyer, J.

1994-02-01

A non-invasive diagnostic tool that could identify malignancy in situ and in real time would have a major impact on the detection and treatment of cancer. We have developed and are testing early prototypes of an optical biopsy system (OBS) for detection of cancer and other tissue pathologies. The OBS invokes a unique approach to optical diagnosis of tissue pathologies based on the elastic scattering properties, over a wide range of wavelengths, of the microscopic structure of the tissue. Absorption bands in the tissue also add useful complexity to the spectral data collected. The use of elastic scattering as themore » key to optical tissue diagnostics in the OBS is based on the fact that many tissue pathologies, including a majority of cancer forms, manifest significant architectural changes at the cellular and sub-cellular level. Since the cellular components that cause elastic scattering have dimensions typically on the order of visible to near-IR wavelengths, the elastic (Mie) scattering properties will be strongly wavelength dependent. Thus, morphology and size changes can be expected to cause significant changes in an optical signature that is derived from the wavelength-dependence of elastic scattering as well as absorption. The data acquisition and storage/display time with the OBS instrument is {approximately}1 second. Thus, in addition to the reduced invasiveness of this technique compared with current state-of-the-art methods (surgical biopsy and pathology analysis), the OBS offers the possibility of impressively faster diagnostic assessment. The OBS employs a small fiber-optic probe that is amenable to use with any endoscope, catheter or hypodermic, or to direct surface examination (e.g., as in skin cancer or cervical cancer). We report here specifically on its potential application in the detection of bladder cancer.« less

Optical imaging probes in oncology

PubMed Central

Martelli, Cristina; Dico, Alessia Lo; Diceglie, Cecilia; Lucignani, Giovanni; Ottobrini, Luisa

2016-01-01

Cancer is a complex disease, characterized by alteration of different physiological molecular processes and cellular features. Keeping this in mind, the possibility of early identification and detection of specific tumor biomarkers by non-invasive approaches could improve early diagnosis and patient management. Different molecular imaging procedures provide powerful tools for detection and non-invasive characterization of oncological lesions. Clinical studies are mainly based on the use of computed tomography, nuclear-based imaging techniques and magnetic resonance imaging. Preclinical imaging in small animal models entails the use of dedicated instruments, and beyond the already cited imaging techniques, it includes also optical imaging studies. Optical imaging strategies are based on the use of luminescent or fluorescent reporter genes or injectable fluorescent or luminescent probes that provide the possibility to study tumor features even by means of fluorescence and luminescence imaging. Currently, most of these probes are used only in animal models, but the possibility of applying some of them also in the clinics is under evaluation. The importance of tumor imaging, the ease of use of optical imaging instruments, the commercial availability of a wide range of probes as well as the continuous description of newly developed probes, demonstrate the significance of these applications. The aim of this review is providing a complete description of the possible optical imaging procedures available for the non-invasive assessment of tumor features in oncological murine models. In particular, the characteristics of both commercially available and newly developed probes will be outlined and discussed. PMID:27145373

Optical Coherence Tomography

NASA Astrophysics Data System (ADS)

Huang, David

Optical coherence tomography (OCT) is a new method for noninvasive cross-sectional imaging in biological systems. In OCT, the longitudinal locations of tissue structures are determined by measuring the time-of-flight delays of light backscattered from these structures. The optical delays are measured by low coherence interferometry. Information on lateral position is provided by transverse scanning of the probe beam. The two dimensional map of optical scattering from internal tissue microstructures is then represented in a false-color or grayscale image. OCT is the optical analog of ultrasonic pulse-echo imaging, but with greatly improved spatial resolutions (a few microns). This thesis describes the development of this new high resolution tomographic imaging technology and the demonstration of its use in a variety of tissues under both in vitro and in vivo conditions. In vitro OCT ranging and imaging studies were performed using human ocular and arterial tissues, two clinically relevant examples of transparent and turbid media, respectively. In the anterior eye, precise measurements of cornea and anterior chamber dimensions were made. In the arterial specimens, the differentiation between fatty -calcified and fibromuscular tissues was demonstrated. In vivo OCT imaging in the retina and optic nerve head in human subjects was also performed. The delineation of retinal layers, which has not been possible with other noninvasive imaging techniques, is demonstrated in these OCT images. OCT has high spatial resolution but limited penetration into turbid tissue. It has potential for diagnostic applications where high resolution is needed and optical access is available, such as in the eye, skin, surgically exposed tissues, and surfaces that can be reached by various catheters and endoscopic probes. In particular, the measurement of fine retinal structures promises improvements in the diagnosis and management of glaucoma, macular edema and other vitreo-retinal diseases. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253 -1690.).

Nonthermal ablation with microbubble-enhanced focused ultrasound close to the optic tract without affecting nerve function.

PubMed

McDannold, Nathan; Zhang, Yong-Zhi; Power, Chanikarn; Jolesz, Ferenc; Vykhodtseva, Natalia

2013-11-01

Tumors at the skull base are challenging for both resection and radiosurgery given the presence of critical adjacent structures, such as cranial nerves, blood vessels, and brainstem. Magnetic resonance imaging-guided thermal ablation via laser or other methods has been evaluated as a minimally invasive alternative to these techniques in the brain. Focused ultrasound (FUS) offers a noninvasive method of thermal ablation; however, skull heating limits currently available technology to ablation at regions distant from the skull bone. Here, the authors evaluated a method that circumvents this problem by combining the FUS exposures with injected microbubble-based ultrasound contrast agent. These microbubbles concentrate the ultrasound-induced effects on the vasculature, enabling an ablation method that does not cause significant heating of the brain or skull. In 29 rats, a 525-kHz FUS transducer was used to ablate tissue structures at the skull base that were centered on or adjacent to the optic tract or chiasm. Low-intensity, low-duty-cycle ultrasound exposures (sonications) were applied for 5 minutes after intravenous injection of an ultrasound contrast agent (Definity, Lantheus Medical Imaging Inc.). Using histological analysis and visual evoked potential (VEP) measurements, the authors determined whether structural or functional damage was induced in the optic tract or chiasm. Overall, while the sonications produced a well-defined lesion in the gray matter targets, the adjacent tract and chiasm had comparatively little or no damage. No significant changes (p > 0.05) were found in the magnitude or latency of the VEP recordings, either immediately after sonication or at later times up to 4 weeks after sonication, and no delayed effects were evident in the histological features of the optic nerve and retina. This technique, which selectively targets the intravascular microbubbles, appears to be a promising method of noninvasively producing sharply demarcated lesions in deep brain structures while preserving function in adjacent nerves. Because of low vascularity--and thus a low microbubble concentration--some large white matter tracts appear to have some natural resistance to this type of ablation compared with gray matter. While future work is needed to develop methods of monitoring the procedure and establishing its safety at deep brain targets, the technique does appear to be a potential solution that allows FUS ablation of deep brain targets while sparing adjacent nerve structures.

The theory behind the full scattering profile

NASA Astrophysics Data System (ADS)

Feder, Idit; Duadi, Hamootal; Fixler, Dror

2018-02-01

Optical methods for extracting properties of tissues are commonly used. These methods are non-invasive, cause no harm to the patient and are characterized by high speed. The human tissue is a turbid media hence it poses a challenge for different optical methods. In addition the analysis of the emitted light requires calibration for achieving accuracy information. Most of the methods analyze the reflected light based on their phase and amplitude or the transmitted light. We suggest a new optical method for extracting optical properties of cylindrical tissues based on their full scattering profile (FSP), which means the angular distribution of the reemitted light. The FSP of cylindrical tissues is relevant for biomedical measurement of fingers, earlobes or pinched tissues. We found the iso-pathlength (IPL) point, a point on the surface of the cylinder medium where the light intensity remains constant and does not depend on the reduced scattering coefficient of the medium, but rather depends on the spatial structure and the cylindrical geometry. However, a similar behavior was also previously reported in reflection from a semi-infinite medium. Moreover, we presented a linear dependency between the radius of the tissue and the point's location. This point can be used as a self-calibration point and thus improve the accuracy of optical tissue measurements. This natural phenomenon has not been investigated before. We show this phenomenon theoretically, based on the diffusion theory, which is supported by our simulation results using Monte Carlo simulation.

In-vitro bacterial identification using fluorescence spectroscopy with an optical fiber system

NASA Astrophysics Data System (ADS)

Spector, Brian C.; Werkhaven, Jay A.; Smith, Dana; Reinisch, Lou

2000-05-01

Acute otitis media (AOM) remains a source of significant morbidity in children. With the emergence of antibiotic resistant strains of bacteria, tympanocentesis has become an important method of bacterial identification in the setting of treatment failures. Previous studies described a prototype system for the non-invasive fluorescence identification of bacteria in vitro. We demonstrate the addition of an optical fiber to allow for the identification of a specimen distant to the spectrofluorometer. Emission spectra from three bacteria, Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus were successfully obtained in vitro. This represents a necessary step prior to the study of in vivo identification of bacteria in AOM using fluorescence spectroscopy.

Novel Method of Noninvasive Detection and Assessment of Gas Emboli and DCS

DTIC Science & Technology

2010-12-10

University of Houston, 4800 Calhoun Rd., 3605 Cullen Blvd Houston, TX 77204-5060 036837920 Undersea Medicine & Noise Induced Hearing Loss, Office of... Undersea Medicine Research Program (Code: 34; PO: CDR Matthew Swiergosz). Introduction Formation of microbubbles in the human body has...esponse at 665 tte with respe glass thicknes ces of glass cu 00 µm thick g to 1,2,3,4 i -D profile sho µm peak. ct to the beam s, B- optical

Near-infrared signals associated with electrical stimulation of peripheral nerves

NASA Astrophysics Data System (ADS)

Fantini, Sergio; Chen, Debbie K.; Martin, Jeffrey M.; Sassaroli, Angelo; Bergethon, Peter R.

2009-02-01

We report our studies on the optical signals measured non-invasively on electrically stimulated peripheral nerves. The stimulation consists of the delivery of 0.1 ms current pulses, below the threshold for triggering any visible motion, to a peripheral nerve in human subjects (we have studied the sural nerve and the median nerve). In response to electrical stimulation, we observe an optical signal that peaks at about 100 ms post-stimulus, on a much longer time scale than the few milliseconds duration of the electrical response, or sensory nerve action potential (SNAP). While the 100 ms optical signal we measured is not a direct optical signature of neural activation, it is nevertheless indicative of a mediated response to neural activation. We argue that this may provide information useful for understanding the origin of the fast optical signal (also on a 100 ms time scale) that has been measured non-invasively in the brain in response to cerebral activation. Furthermore, the optical response to peripheral nerve activation may be developed into a diagnostic tool for peripheral neuropathies, as suggested by the delayed optical signals (average peak time: 230 ms) measured in patients with diabetic neuropathy with respect to normal subjects (average peak time: 160 ms).

Polymerization shrinkage of a dental resin composite determined by a fiber optic Fizeau interferometer

NASA Astrophysics Data System (ADS)

Arenas, Gustavo; Noriega, Sergio; Vallo, Claudia; Duchowicz, Ricardo

2007-03-01

A fiber optic sensing method based on a Fizeau-type interferometric scheme was employed for monitoring linear polymerization shrinkage in dental restoratives. This technique offers several advantages over the conventional methods of measuring polymerization contraction. This simple, compact, non-invasive and self-calibrating system competes with both conventional and other high-resolution bulk interferometric techniques. In this work, an analysis of the quality of interference signal and fringes visibility was performed in order to characterize their resolution and application range. The measurements of percent linear contraction as a function of the sample thickness were carried out in this study on two dental composites: Filtek P60 (3M ESPE) Posterior Restorer and Filtek Z250 (3M ESPE) Universal Restorer. The results were discussed with respect to others obtained employing alternative techniques.

Dynamic focus optical coherence tomography: feasibility for improved basal cell carcinoma investigation

NASA Astrophysics Data System (ADS)

Nasiri-Avanaki, M. R.; Aber, Ahmed; Hojjatoleslami, S. A.; Sira, Mano; Schofield, John B.; Jones, Carole; Podoleanu, A. Gh.

2012-03-01

Basal cell carcinoma (BCC) is the most common form of skin cancer. To improve the diagnostic accuracy, additional non-invasive methods of making a preliminary diagnosis have been sought. We have implemented an En-Face optical coherence tomography (OCT) for this study in which the dynamic focus was integrated into it. With the dynamic focus scheme, the coherence gate moves synchronously with the peak of confocal gate determined by the confocal interface optics. The transversal resolution is then conserved throughout the depth range and an enhanced signal is returned from all depths. The Basal Cell Carcinoma specimens were obtained from the eyelid a patient. The specimens under went analysis by DF-OCT imaging. We searched for remarkable features that were visualized by OCT and compared these findings with features presented in the histology slices.

Reflectance confocal microscopy of optical phantoms

PubMed Central

Jacques, Steven L.; Wang, Bo; Samatham, Ravikant

2012-01-01

A reflectance confocal scanning laser microscope (rCSLM) operating at 488-nm wavelength imaged three types of optical phantoms: (1) 100-nm-dia. polystyrene microspheres in gel at 2% volume fraction, (2) solid polyurethane phantoms (INO BiomimicTM), and (3) common reflectance standards (SpectralonTM). The noninvasive method measured the exponential decay of reflected signal as the focus (zf) moved deeper into the material. The two experimental values, the attenuation coefficient μ and the pre-exponential factor ρ, were mapped into the material optical scattering properties, the scattering coefficient μs and the anisotropy of scattering g. Results show that μs varies as 58, 8–24, and 130–200 cm-1 for phantom types (1), (2) and (3), respectively. The g varies as 0.112, 0.53–0.67, and 0.003–0.26, respectively. PMID:22741065

Micro-optical coherence tomography of the mammalian cochlea

PubMed Central

Iyer, Janani S.; Batts, Shelley A.; Chu, Kengyeh K.; Sahin, Mehmet I.; Leung, Hui Min; Tearney, Guillermo J.; Stankovic, Konstantina M.

2016-01-01

The mammalian cochlea has historically resisted attempts at high-resolution, non-invasive imaging due to its small size, complex three-dimensional structure, and embedded location within the temporal bone. As a result, little is known about the relationship between an individual’s cochlear pathology and hearing function, and otologists must rely on physiological testing and imaging methods that offer limited resolution to obtain information about the inner ear prior to performing surgery. Micro-optical coherence tomography (μOCT) is a non-invasive, low-coherence interferometric imaging technique capable of resolving cellular-level anatomic structures. To determine whether μOCT is capable of resolving mammalian intracochlear anatomy, fixed guinea pig inner ears were imaged as whole temporal bones with cochlea in situ. Anatomical structures such as the tunnel of Corti, space of Nuel, modiolus, scalae, and cell groupings were visualized, in addition to individual cell types such as neuronal fibers, hair cells, and supporting cells. Visualization of these structures, via volumetrically-reconstructed image stacks and endoscopic perspective videos, represents an improvement over previous efforts using conventional OCT. These are the first μOCT images of mammalian cochlear anatomy, and they demonstrate μOCT’s potential utility as an imaging tool in otology research. PMID:27633610

Various new applications of fiber optic infrared Fourier transform spectroscopy for dermatology

NASA Astrophysics Data System (ADS)

Bruch, Reinhard F.; Afanasyeva, Natalia I.; Sukuta, Sydney; Brooks, Angelique L.; Makhine, Volodymyr; Kolyakov, Sergei F.

1999-02-01

Fiberoptical evanescent wave Fourier transform infrared (FEW- FTIR) spectroscopy has been applied in the middle infrared (MIR) wavelength range (3 to 20 micrometer) to the in vivo diagnostics of normal skin tissue, acupuncture points as well as precancerous and cancerous conditions. The FTIR-FEW technique, using nontoxic unclad fibers, is suitable for noninvasive, sensitive investigations of skin tissue for various dermatological studies of skin caner, aging, laser treatment, cosmetics, skin allergies, etc. This method is direct, nondestructive, and fast (seconds). Our optical fibers are nonhygroscopic, flexible, and characterized by extremely low losses. In this study, we have noninvasively investigated more than 300 cases of normal skin, acupuncture points, precancerous and cancerous tissue in the range of 1400 to 1800 cm-1. The results of our analysis of skin and other tissue are discussed in terms of structural and mathematical similarities and differences on a molecular level. In addition, we have also performed cluster analysis, using principal component scores, to confirm pathological classifications and to discriminate between genders. We have found good agreement with prior pathological classifications for normal skin tissue and melanoma tumors and normal females were distinctly separate from males.

Evaluating the use of optical coherence tomography for the detection of epithelial cancers in vitro

NASA Astrophysics Data System (ADS)

Smith, Louise E.; Hearnden, Vanessa; Lu, Zenghai; Smallwood, Rod; Hunter, Keith D.; Matcher, Stephen J.; Thornhill, Martin H.; Murdoch, Craig; MacNeil, Sheila

2011-11-01

Optical coherence tomography (OCT) is a noninvasive imaging methodology that is able to image tissue to depths of over 1 mm. Many epithelial conditions, such as melanoma and oral cancers, require an invasive biopsy for diagnosis. A noninvasive, real-time, point of care method of imaging depth-resolved epithelial structure could greatly improve early diagnosis and long-term monitoring in patients. Here, we have used tissue-engineered (TE) models of normal skin and oral mucosa to generate models of melanoma and oral cancer. We have used these to determine the ability of OCT to image epithelial differences in vitro. We report that while in vivo OCT gives reasonable depth information for both skin and oral mucosa, in vitro the information provided is less detailed but still useful. OCT can provide reassurance on the development of TE models of skin and oral mucosa as they develop in vitro. OCT was able to detect the gross alteration in the epithelium of skin and mucosal models generated with malignant cell lines but was less able to detect alteration in the epithelium of TE models that mimicked oral dysplasia or, in models where tumor cells had penetrated into the dermis.

Analyses of the correlation between dermal and blood carotenoids in female cattle by optical methods

NASA Astrophysics Data System (ADS)

Klein, Julia; Darvin, Maxim E.; Meinke, Martina C.; Schweigert, Florian J.; Müller, Kerstin E.; Lademann, Jürgen

2013-06-01

Herd health programs for the maintenance of welfare and productivity in cattle need efficient tools for monitoring the health of individual animals. Recent reports demonstrate that the oxidative status is related to various stress conditions in dairy cows. Biomarkers, among other carotenoids, could serve as indicators of stress originating from the environment (e.g., heat stress or sun radiation) or from the animal itself (e.g., disease). To date, only invasive in vitro tests are available to assess the oxidative status in cattle. The present study compares the results of optical noninvasive in vivo measurements of dermal carotenoids in cattle udder skin using an LED-based miniaturized spectroscopic system (MSS) with those obtained by photometric analysis of beta carotene in whole blood samples using a portable device. Correlations between the concentrations of dermal and blood carotenoids were calculated under consideration of the nutritional status of the animals. Significant correlation (R=0.86) was found for cattle with a moderate to obese body condition. Thus, the blood and skin concentrations of the marker substance beta carotene are comparable under stable stress conditions of the cattle. This demonstrates that the MSS is suitable for noninvasive assessment of dermal carotenoid concentrations in cattle.

NIR-labeled perfluoropolyether nanoemulsions for drug delivery and imaging

PubMed Central

O’Hanlon, Claire E.; Amede, Konjit G.; O’Hear, Meredith R.; Janjic, Jelena M.

2012-01-01

Theranostic nanoparticle development recently took center stage in the field of drug delivery nanoreagent design. Theranostic nanoparticles combine therapeutic delivery systems (liposomes, micelles, nanoemulsions, etc.) with imaging reagents (MRI, optical, PET, CT). This combination allows for non-invasive in vivo monitoring of therapeutic nanoparticles in diseased organs and tissues. Here, we report a novel perfluoropolyether (PFPE) nanoemulsion with a water-insoluble lipophilic drug. The formulation enables non-invasive monitoring of nanoemulsion biodistribution using two imaging modalities, 19F MRI and near-infrared (NIR) optical imaging. The nanoemulsion is composed of PFPE-tyramide as a 19F MRI tracer, hydrocarbon oil, surfactants, and a NIR dye. Preparation utilizes a combination of self-assembly and high energy emulsification methods, resulting in droplets with average diameter 180 nm and low polydispersity index (PDI less than 0.2). A model nonsteroidal anti-inflammatory drug (NSAID), celecoxib, was incorporated into the formulation at 0.2 mg/mL. The reported nanoemulsion’s properties, including small particle size, visibility under 19F NMR and NIR fluorescence spectroscopy, and the ability to carry drugs make it an attractive potential theranostic agent for cancer imaging and treatment. PMID:22675234

Effect of flow velocity on the photoacoustic detection for glucose aqueous solutions

NASA Astrophysics Data System (ADS)

Ren, Zhong; Liu, Guodong; Ding, Yu; Yao, Qingkai

2018-01-01

The blood glucose non-invasive detection has become the research hot-spot. The photoacoustic spectroscopy is a well-promising, high-efficient and noninvasive detection method because it combines the advantages of the pure optic and pure ultrasonic. In practice, the photoacoustic detection of blood glucose is impacted by many factors because the human body is a complicated bio-system. To study the effect of flow velocity in the blood vessel on the photoacoustic detection of blood glucose, a photoacoustic detection system based on optical parameter oscillator (OPO) pulsed laser induced ultrasonic was established. In this system, a 532nm pumped Nd: YAG OPO pulsed laser was used as the excitation source, and the photoacoustic signals of glucose were captured by ultrasonic transducer. Moreover, a set of blood circulation system was built to simulate the real blood flow situation in the human body. The experiments of the photoacoustic detection of glucose aqueous solutions with different concentrations at different flow velocities were experimentally investigated. Experimental results show that the photoacoustic peak-to-peak value linearly increases with the glucose concentration, but it decreases with the increase of the flow velocity although the profiles of photoacoustic signals don't change.

Burn-injured tissue detection for debridement surgery through the combination of non-invasive optical imaging techniques.

PubMed

Heredia-Juesas, Juan; Thatcher, Jeffrey E; Lu, Yang; Squiers, John J; King, Darlene; Fan, Wensheng; DiMaio, J Michael; Martinez-Lorenzo, Jose A

2018-04-01

The process of burn debridement is a challenging technique requiring significant skills to identify the regions that need excision and their appropriate excision depths. In order to assist surgeons, a machine learning tool is being developed to provide a quantitative assessment of burn-injured tissue. This paper presents three non-invasive optical imaging techniques capable of distinguishing four kinds of tissue-healthy skin, viable wound bed, shallow burn, and deep burn-during serial burn debridement in a porcine model. All combinations of these three techniques have been studied through a k-fold cross-validation method. In terms of global performance, the combination of all three techniques significantly improves the classification accuracy with respect to just one technique, from 0.42 up to more than 0.76. Furthermore, a non-linear spatial filtering based on the mode of a small neighborhood has been applied as a post-processing technique, in order to improve the performance of the classification. Using this technique, the global accuracy reaches a value close to 0.78 and, for some particular tissues and combination of techniques, the accuracy improves by 13%.

Optical tomography of human skin with subcellular spatial and picosecond time resolution using intense near infrared femtosecond laser pulses

NASA Astrophysics Data System (ADS)

Koenig, Karsten; Wollina, Uwe; Riemann, Iris; Peukert, Christiane; Halbhuber, Karl-Juergen; Konrad, Helga; Fischer, Peter; Fuenfstueck, Veronika; Fischer, Tobias W.; Elsner, Peter

2002-06-01

We describe the novel high resolution imaging tool DermaInspect 100 for non-invasive diagnosis of dermatological disorders based on multiphoton autofluorescence imaging (MAI)and second harmonic generation. Femtosecond laser pulses in the spectral range of 750 nm to 850 nm have been used to image in vitro and in vivo human skin with subcellular spatial and picosecond temporal resolution. The non-linear induced autofluorescence originates mainly from naturally endogenous fluorophores/protein structures like NAD(P)H, flavins, keratin, collagen, elastin, porphyrins and melanin. Second harmonic generation was observed in the stratum corneum and in the dermis. The system with a wavelength-tunable compact 80 MHz Ti:sapphire laser, a scan module with galvo scan mirrors, piezoelectric objective positioner, fast photon detector and time-resolved single photon counting unit was used to perform optical sectioning and 3D autofluorescence lifetime imaging (t-mapping). In addition, a modified femtosecond laser scanning microscope was involved in autofluorescence measurements. Tissues of patients with psoriasis, nevi, dermatitis, basalioma and melanoma have been investigated. Individual cells and skin structures could be clearly visualized. Intracellular components and connective tissue structures could be further characterized by tuning the excitation wavelength in the range of 750 nm to 850 nm and by calculation of mean fluorescence lifetimes per pixel and of particular regions of interest. The novel non-invasive imaging system provides 4D (x,y,z,t) optical biopsies with subcellular resolution and offers the possibility to introduce a further optical diagnostic method in dermatology.

Near-infrared oxymeter biosensor prototype for non-invasive in vivo analysis of rat brain oxygenation: effects of drugs of abuse

NASA Astrophysics Data System (ADS)

Crespi, F.; Donini, M.; Bandera, A.; Congestri, F.; Formenti, F.; Sonntag, V.; Heidbreder, C.; Rovati, L.

2006-07-01

The feasibility of non-invasive analysis of brain activities was studied in the attempt to overcome the major limitation of actual in vivo methodologies, i.e. invasiveness. Optic fibre probes were used as the optical head of a novel, highly sensitive near-infrared continuous wave spectroscopy (CW-NIR) instrument. This prototype was designed for non-invasive analysis of the two main forms of haemoglobin: oxy-haemoglobin (HbO2) and deoxy-haemoglobin (Hb), chromophores present in biological tissues. It was tested in peripheral tissue (human gastrocnemius muscle) and then reset to perform the measurement on rat brain. In animal studies, the optical head was firmly placed using stereotaxic apparatus upon the sagittal line of the head of anaesthetized adult rats, without any surgery. Then pharmacological treatments with saline (300 µl s.c.) amphetamine (2 mg kg-1) or nicotine (0.4 mg kg-1) were performed. Within 10-20 min amphetamine substantially increased HbO2 and reduced Hb control levels. Nicotine produced a rapid initial increase followed by a decrease in HbO2. In contrast to amphetamine, nicotine treatment also reduced Hb and blood volume. These results support the capacity of our CW-NIR prototype to measure non-invasively HbO2 and Hb levels in the rat brain, that are markers of the degree of tissue oxygenation, thus providing an index of blood levels and therefore of brain metabolism.

Subsurface thermal coagulation of tissues using near infrared lasers

NASA Astrophysics Data System (ADS)

Chang, Chun-Hung Jack

Noninvasive laser therapy is currently limited primarily to cosmetic dermatological applications such as skin resurfacing, hair removal, tattoo removal and treatment of vascular birthmarks. In order to expand applications of noninvasive laser therapy, deeper optical penetration of laser radiation in tissue as well as more aggressive cooling of the tissue surface is necessary. The near-infrared laser wavelength of 1075 nm was found to be the optimal laser wavelength for creation of deep subsurface thermal lesions in liver tissue, ex vivo, with contact cooling, preserving a surface tissue layer of 2 mm. Monte Carlo light transport, heat transfer, and Arrhenius integral thermal damage simulations were conducted at this wavelength, showing good agreement between experiment and simulations. Building on the initial results, our goal is to develop new noninvasive laser therapies for application in urology, specifically for treatment of female stress urinary incontinence (SUI). Various laser balloon probes including side-firing and diffusing fibers were designed and tested for both transvaginal and transurethral approaches to treatment. The transvaginal approach showed the highest feasibility. To further increase optical penetration depth, various types and concentrations of optical clearing agents were also explored. Three cadavers studies were performed to investigate and demonstrate the feasibility of laser treatment for SUI.

Dynamics of blood plasma by spectropolarimetry and biochemical techniques

NASA Astrophysics Data System (ADS)

Voloshynska, Katerina; Ilashchuka, Tetjana; Prydij, Olexander; Gruia, Maria

2014-08-01

The aim of the study was to establish objective parameters of the field of laser and incoherent radiation of different spectral ranges (UV, visible, IR) as a non-invasive optical method of interaction with different samples of biological tissues and fluids of patients to determine the dynamics of metabolic syndrome and choosing the best personal treatment. As diagnostic methods have been used ultraviolet spectrometry samples of blood plasma in the liquid state, infrared spectroscopy middle range (2,5 - 25 microns) dry residue of plasma polarization and laser diagnostic technique of thin histological sections of biological tissues.

Spectropolarimetry of blood plasma in optimal molecular targeted therapy

NASA Astrophysics Data System (ADS)

Voloshynska, Katerina; Ilashchuk, Tetjana; Yermolenko, Sergey

2015-02-01

The aim of the study was to establish objective parameters of the field of laser and incoherent radiation of different spectral ranges (UV, visible, IR) as a non-invasive optical method of interaction with different samples of biological tissues and fluids of patients to determine the dynamics of metabolic syndrome and choosing the best personal treatment. As diagnostic methods have been used ultraviolet spectrometry samples of blood plasma in the liquid state, infrared spectroscopy middle range (2,5 - 25 microns) dry residue of plasma polarization and laser diagnostic technique of thin histological sections of biological tissues.

Application of Elastography for the Noninvasive Assessment of Biomechanics in Engineered Biomaterials and Tissues

PubMed Central

Kim, Woong; Ferguson, Virginia L.; Borden, Mark; Neu, Corey P.

2016-01-01

The elastic properties of engineered biomaterials and tissues impact their post-implantation repair potential and structural integrity, and are critical to help regulate cell fate and gene expression. The measurement of properties (e.g., stiffness or shear modulus) can be attained using elastography, which exploits noninvasive imaging modalities to provide functional information of a material indicative of the regeneration state. In this review, we outline the current leading elastography methodologies available to characterize the properties of biomaterials and tissues suitable for repair and mechanobiology research. We describe methods utilizing magnetic resonance, ultrasound, and optical coherent elastography, highlighting their potential for longitudinal monitoring of implanted materials in vivo, in addition to spatiotemporal limits of each method for probing changes in cell-laden constructs. Micro-elastography methods now allow acquisitions at length scales approaching 5–100 μm in two and three dimensions. Many of the methods introduced in this review are therefore capable of longitudinal monitoring in biomaterials and tissues approaching the cellular scale. However, critical factors such as anisotropy, heterogeneity and viscoelasity—inherent in many soft tissues—are often not fully described and therefore require further advancements and future developments. PMID:26790865

Analysis of the potential for non-invasive imaging of oxygenation at heart depth, using ultrasound optical tomography (UOT) or photo-acoustic tomography (PAT).

PubMed

Walther, Andreas; Rippe, Lars; Wang, Lihong V; Andersson-Engels, Stefan; Kröll, Stefan

2017-10-01

Despite the important medical implications, it is currently an open task to find optical non-invasive techniques that can image deep organs in humans. Addressing this, photo-acoustic tomography (PAT) has received a great deal of attention in the past decade, owing to favorable properties like high contrast and high spatial resolution. However, even with optimal components PAT cannot penetrate beyond a few centimeters, which still presents an important limitation of the technique. Here, we calculate the absorption contrast levels for PAT and for ultrasound optical tomography (UOT) and compare them to their relevant noise sources as a function of imaging depth. The results indicate that a new development in optical filters, based on rare-earth-ion crystals, can push the UOT technique significantly ahead of PAT. Such filters allow the contrast-to-noise ratio for UOT to be up to three orders of magnitude better than for PAT at depths of a few cm into the tissue. It also translates into a significant increase of the image depth of UOT compared to PAT, enabling deep organs to be imaged in humans in real time. Furthermore, such spectral holeburning filters are not sensitive to speckle decorrelation from the tissue and can operate at nearly any angle of incident light, allowing good light collection. We theoretically demonstrate the improved performance in the medically important case of non-invasive optical imaging of the oxygenation level of the frontal part of the human myocardial tissue. Our results indicate that further studies on UOT are of interest and that the technique may have large impact on future directions of biomedical optics.

Noninvasive Imaging of Retinal Morphology and Microvasculature in Obese Mice Using Optical Coherence Tomography and Optical Microangiography

PubMed Central

Zhi, Zhongwei; Chao, Jennifer R.; Wietecha, Tomasz; Hudkins, Kelly L.; Alpers, Charles E.; Wang, Ruikang K.

2014-01-01

Purpose. To evaluate early diabetes-induced changes in retinal thickness and microvasculature in a type 2 diabetic mouse model by using optical coherence tomography (OCT)/optical microangiography (OMAG). Methods. Twenty-two-week-old obese (OB) BTBR mice (n = 10) and wild-type (WT) control mice (n = 10) were imaged. Three-dimensional (3D) data volumes were captured with spectral domain OCT using an ultrahigh-sensitive OMAG scanning protocol for 3D volumetric angiography of the retina and dense A-scan protocol for measurement of the total retinal blood flow (RBF) rate. The thicknesses of the nerve fiber layer (NFL) and that of the NFL to the inner plexiform layer (IPL) were measured and compared between OB and WT mice. The linear capillary densities within intermediate and deep capillary layers were determined by the number of capillaries crossing a 500-μm line. The RBF rate was evaluated using an en face Doppler approach. These quantitative measurements were compared between OB and WT mice. Results. The retinal thickness of the NFL to IPL was significantly reduced in OB mice (P < 0.01) compared to that in WT mice, whereas the NFL thickness between the two was unchanged. 3D depth-resolved OMAG angiography revealed the first in vivo 3D model of mouse retinal microcirculation. Although no obvious differences in capillary vessel densities of the intermediate and deep capillary layers were detected between normal and OB mice, the total RBF rate was significantly lower (P < 0.05) in OB mice than in WT mice. Conclusions. We conclude that OB BTBR mice have significantly reduced NFL–IPL thicknesses and total RBF rates compared with those of WT mice, as imaged by OCT/OMAG. OMAG provides an unprecedented capability for high-resolution depth-resolved imaging of mouse retinal vessels and blood flow that may play a pivotal role in providing a noninvasive method for detecting early microvascular changes in patients with diabetic retinopathy. PMID:24458155

Bone regeneration assessment by optical coherence tomography and MicroCT synchrotron radiation

NASA Astrophysics Data System (ADS)

Negrutiu, Meda L.; Sinescu, Cosmin; Canjau, Silvana; Manescu, Adrian; Topalá, Florin I.; Hoinoiu, Bogdan; Romînu, Mihai; Márcáuteanu, Corina; Duma, Virgil; Bradu, Adrian; Podoleanu, Adrian G.

2013-06-01

Bone grafting is a commonly performed surgical procedure to augment bone regeneration in a variety of orthopaedic and maxillofacial procedures, with autologous bone being considered as the "gold standard" bone-grafting material, as it combines all properties required in a bone-graft material: osteoinduction (bone morphogenetic proteins - BMPs - and other growth factors), osteogenesis (osteoprogenitor cells) and osteoconduction (scaffold). The problematic elements of bone regenerative materials are represented by their quality control methods, the adjustment of the initial bone regenerative material, the monitoring (noninvasive, if possible) during their osteoconduction and osteointegration period and biomedical evaluation of the new regenerated bone. One of the research directions was the interface investigation of the regenerative bone materials and their behavior at different time periods on the normal femoral rat bone. 12 rat femurs were used for this investigation. In each ones a 1 mm diameter hole were drilled and a bone grafting material was inserted in the artificial defect. The femurs were removed after one, three and six months. The defects repaired by bone grafting material were evaluated by optical coherence tomography working in Time Domain Mode at 1300 nm. Three dimensional reconstructions of the interfaces were generated. The validations of the results were evaluated by microCT. Synchrotron Radiation allows achieving high spatial resolution images to be generated with high signal-to-noise ratio. In addition, Synchrotron Radiation allows acquisition of volumes at different energies and volume subtraction to enhance contrast. Evaluation of the bone grafting material/bone interface with noninvasive methods such as optical coherence tomography could act as a valuable procedure that can be use in the future in the usual clinical techniques. The results were confirmed by microCT. Optical coherence tomography can be performed in vivo and can provide a qualitative and quantitative evaluation of the bone augmentation procedure.

Simultaneous determination of hemolysis and hematocrit in extracorporeal circulation by plasma surface reflectance spectroscopy.

PubMed

Sakota, Daisuke; Kani, Yuki; Kosaka, Ryo; Nishida, Masahiro; Maruyama, Osamu

2013-01-01

To achieve quantitative non-invasive optical diagnosis of blood abnormalities during extracorporeal circulation therapies, plasma surface reflectance spectroscopy was developed by implementing oblique-incidence optical fiber reflectometry on the surface of circulating blood. The reflected light in the wavelength range from 450 to 600 nm changed with respect to the plasma free hemoglobin level and could be used to quantify the free hemoglobin at an accuracy of 5.7 ± 3.5 mg/dL. In contrast, the spectrum did not changed by varying the hematocrit. In the wavelength range from 600 to 800 nm, the obtained spectrum was affected by both the hematocrit change and hemolysis. The linear correlation between the hematocrit value and the spectrum was confirmed at R(2) = 0.99. The feasibility of determining of the hematocrit of arbitrary hemolyzed blood was confirmed. The developed system permits the extraction of the optical characteristics of both plasma and red blood cells without centrifugation. The study establishes non-invasive optical diagnostics capable of analyzing the optical properties of both plasma and red blood cells.

Noninvasive photoacoustic identification and imaging of gut microbes.

PubMed

Huang, Xiaoxiao; Shi, Ying; Liu, Yajing; Xu, Hongzhi; Liu, Yu; Xiao, Chuanxing; Ren, Jianlin; Nie, Liming

2017-08-01

Homeostasis of the gut microbiota is indispensable for various physiological functions. Its composition and activity co-develop with the host, and especially associate with human colorectal cancer. However, current composition identification methods are complicated and not timely without spatial distribution information. In this Letter, we explored the photoacoustic imaging (PAI) technique to characterize the composition and quantify the proportions of the gut microbes after optical probe labeling. Our experimental results demonstrated that PAI has the potential to identify different gut bacterial species on the spot.

Novel Method of Noninvasive Detection and Assessment of Gas Emboli and DCS

DTIC Science & Technology

2010-12-01

Young Investigator Program, Undersea Medicine Research Program (Code: 34; PO: CDR Matthew Swiergosz). Report Documentation Page Form...esponse at 665 tte with respe glass thicknes ces of glass cu 00 µm thick g to 1,2,3,4 i -D profile sho µm peak. ct to the beam s, B- optical vette...arterial CO2 embolism occuring after laparoscopic surgery: A case report," Undersea & Hyperbaric Medicine, vol. 33, pp. 317-320, Sep-Oct 2006. [29] T

Comparative analysis of gingival phenotype in animal and human experimental models using optical coherence tomography in a non-invasive approach

NASA Astrophysics Data System (ADS)

Mota, Cláudia C. B. O.; Fernandes, Luana O.; Melo, Luciana S. A.; Feitosa, Daniela S.; Cimões, Renata; Gomes, Anderson S. L.

2015-06-01

Imaging methods are widely used in diagnostic and among the diversity of modalities, optical coherence tomography (OCT) is nowadays commercially available and considered the most innovative technique used for imaging applications, in both medical and non-medical applications. In this study, we exploit the OCT technique in the oral cavity for identification and differentiation between free and attached gingiva, as well as determining the gingival phenotype, an important factor to determination of periodontal prognosis in patients. For the animal studies, five porcine jaws were analyzed using a Swept Source SS-OCT system operating at 1325nm and stereomicroscope, as gold pattern. The SSOCT at 1325nm was chosen due to the longer central wavelength, that allows to deeper penetration imaging, and the faster image acquisition, an essential factor for clinical setting. For the patient studies, a total of 30 males and female were examined using the SS-OCT at 1325nm and computer controlled periodontal probing. 2D and 3D images of tooth/gingiva interface were performed, and quantitative measurements of the gingival sulcus could be noninvasively obtained. Through the image analysis of the animals jaws, it was possible to quantify the free gingiva and the attached gingiva, the calculus deposition over teeth surface and also the subgingival calculus. For the patient's studies, we demonstrated that the gingival phenotype could be measured without the periodontal probe introduction at the gingival sulcus, confirming that OCT can be potentially useful in clinic for direct observation and quantification of gingival phenotype in a non-invasive approach.

In vivo, noninvasive functional measurements of bone sarcoma using diffuse optical spectroscopic imaging

NASA Astrophysics Data System (ADS)

Peterson, Hannah M.; Hoang, Bang H.; Geller, David; Yang, Rui; Gorlick, Richard; Berger, Jeremy; Tingling, Janet; Roth, Michael; Gill, Jonathon; Roblyer, Darren

2017-12-01

Diffuse optical spectroscopic imaging (DOSI) is an emerging near-infrared imaging technique that noninvasively measures quantitative functional information in thick tissue. This study aimed to assess the feasibility of using DOSI to measure optical contrast from bone sarcomas. These tumors are rare and pose technical and practical challenges for DOSI measurements due to the varied anatomic locations and tissue depths of presentation. Six subjects were enrolled in the study. One subject was unable to be measured due to tissue contact sensitivity. For the five remaining subjects, the signal-to-noise ratio, imaging depth, optical properties, and quantitative tissue concentrations of oxyhemoglobin, deoxyhemoglobin, water, and lipids from tumor and contralateral normal tissues were assessed. Statistical differences between tumor and contralateral normal tissue were found in chromophore concentrations and optical properties for four subjects. Low signal-to-noise was encountered during several subject's measurements, suggesting increased detector sensitivity will help to optimize DOSI for this patient population going forward. This study demonstrates that DOSI is capable of measuring optical properties and obtaining functional information in bone sarcomas. In the future, DOSI may provide a means to stratify treatment groups and monitor chemotherapy response for this disease.

Advances in Bio-Optical Imaging for the Diagnosis of Early Oral Cancer

PubMed Central

Olivo, Malini; Bhuvaneswari, Ramaswamy; Keogh, Ivan

2011-01-01

Oral cancer is among the most common malignancies worldwide, therefore early detection and treatment is imperative. The 5-year survival rate has remained at a dismal 50% for the past several decades. The main reason for the poor survival rate is the fact that most of the oral cancers, despite the general accessibility of the oral cavity, are not diagnosed until the advanced stage. Early detection of the oral tumors and its precursor lesions may be the most effective means to improve clinical outcome and cure most patients. One of the emerging technologies is the use of non-invasive in vivo tissue imaging to capture the molecular changes at high-resolution to improve the detection capability of early stage disease. This review will discuss the use of optical probes and highlight the role of optical imaging such as autofluorescence, fluorescence diagnosis (FD), laser confocal endomicroscopy (LCE), surface enhanced Raman spectroscopy (SERS), optical coherence tomography (OCT) and confocal reflectance microscopy (CRM) in early oral cancer detection. FD is a promising method to differentiate cancerous lesions from benign, thus helping in the determination of adequate resolution of surgical resection margin. LCE offers in vivo cellular imaging of tissue structures from surface to subsurface layers and has demonstrated the potential to be used as a minimally invasive optical biopsy technique for early diagnosis of oral cancer lesions. SERS was able to differentiate between normal and oral cancer patients based on the spectra acquired from saliva of patients. OCT has been used to visualize the detailed histological features of the oral lesions with an imaging depth down to 2–3 mm. CRM is an optical tool to noninvasively image tissue with near histological resolution. These comprehensive diagnostic modalities can also be used to define surgical margin and to provide a direct assessment of the therapeutic effectiveness. PMID:24310585

Towards real-time diffuse optical tomography for imaging brain functions cooperated with Kalman estimator

NASA Astrophysics Data System (ADS)

Wang, Bingyuan; Zhang, Yao; Liu, Dongyuan; Ding, Xuemei; Dan, Mai; Pan, Tiantian; Wang, Yihan; Li, Jiao; Zhou, Zhongxing; Zhang, Limin; Zhao, Huijuan; Gao, Feng

2018-02-01

Functional near-infrared spectroscopy (fNIRS) is a non-invasive neuroimaging method to monitor the cerebral hemodynamic through the optical changes measured at the scalp surface. It has played a more and more important role in psychology and medical imaging communities. Real-time imaging of brain function using NIRS makes it possible to explore some sophisticated human brain functions unexplored before. Kalman estimator has been frequently used in combination with modified Beer-Lamber Law (MBLL) based optical topology (OT), for real-time brain function imaging. However, the spatial resolution of the OT is low, hampering the application of OT in exploring some complicated brain functions. In this paper, we develop a real-time imaging method combining diffuse optical tomography (DOT) and Kalman estimator, much improving the spatial resolution. Instead of only presenting one spatially distributed image indicating the changes of the absorption coefficients at each time point during the recording process, one real-time updated image using the Kalman estimator is provided. Its each voxel represents the amplitude of the hemodynamic response function (HRF) associated with this voxel. We evaluate this method using some simulation experiments, demonstrating that this method can obtain more reliable spatial resolution images. Furthermore, a statistical analysis is also conducted to help to decide whether a voxel in the field of view is activated or not.

Focusing light inside dynamic scattering media with millisecond digital optical phase conjugation

PubMed Central

Liu, Yan; Ma, Cheng; Shen, Yuecheng; Shi, Junhui; Wang, Lihong V.

2017-01-01

Wavefront shaping based on digital optical phase conjugation (DOPC) focuses light through or inside scattering media, but the low speed of DOPC prevents it from being applied to thick, living biological tissue. Although a fast DOPC approach was recently developed, the reported single-shot wavefront measurement method does not work when the goal is to focus light inside, instead of through, highly scattering media. Here, using a ferroelectric liquid crystal based spatial light modulator, we develop a simpler but faster DOPC system that focuses light not only through, but also inside scattering media. By controlling 2.6 × 105 optical degrees of freedom, our system focused light through 3 mm thick moving chicken tissue, with a system latency of 3.0 ms. Using ultrasound-guided DOPC, along with a binary wavefront measurement method, our system focused light inside a scattering medium comprising moving tissue with a latency of 6.0 ms, which is one to two orders of magnitude shorter than those of previous digital wavefront shaping systems. Since the demonstrated speed approaches tissue decorrelation rates, this work is an important step toward in vivo deep-tissue non-invasive optical imaging, manipulation, and therapy. PMID:28815194

Superresolving dendritic spine morphology with STED microscopy under holographic photostimulation

PubMed Central

Lauterbach, Marcel Andreas; Guillon, Marc; Desnos, Claire; Khamsing, Dany; Jaffal, Zahra; Darchen, François; Emiliani, Valentina

2016-01-01

Abstract. Emerging all-optical methods provide unique possibilities for noninvasive studies of physiological processes at the cellular and subcellular scale. On the one hand, superresolution microscopy enables observation of living samples with nanometer resolution. On the other hand, light can be used to stimulate cells due to the advent of optogenetics and photolyzable neurotransmitters. To exploit the full potential of optical stimulation, light must be delivered to specific cells or even parts of cells such as dendritic spines. This can be achieved with computer generated holography (CGH), which shapes light to arbitrary patterns by phase-only modulation. We demonstrate here in detail how CGH can be incorporated into a stimulated emission depletion (STED) microscope for photostimulation of neurons and monitoring of nanoscale morphological changes. We implement an original optical system to allow simultaneous holographic photostimulation and superresolution STED imaging. We present how synapses can be clearly visualized in live cells using membrane stains either with lipophilic organic dyes or with fluorescent proteins. We demonstrate the capabilities of this microscope to precisely monitor morphological changes of dendritic spines after stimulation. These all-optical methods for cell stimulation and monitoring are expected to spread to various fields of biological research in neuroscience and beyond. PMID:27413766

Monitoring scaling and dental calculus removal with an optical fluorescence system

NASA Astrophysics Data System (ADS)

Sivieri-Araujo, G.; Fontana, C. R.; Costa, M. M.; Rastelli, A. N. S.; Pereira, L. P. C.; Kurachi, C.; Bagnato, V. S.

2014-08-01

Fluorescence results from a process that occurs under certain conditions in molecules known as fluorophores, fluorochromes or fluorescent dyes when they absorb light. The molecule is excited to a higher energy state and emits fluorescent light. The emission wavelength is always higher than the excitation wavelength. Optical diagnoses by fluorescence can be used in medicine and dentistry. It does not cause injury to tissues because it is a noninvasive method and can add benefits to clinical treatments. The aim of this case report was to apply an optical fluorescence system for wide-field image viewing and visual monitoring of the management of plaque and dental calculus before and after periodontal scaling to improve the diagnoses and follow-up of patients with periodontal disease. The results suggest that it is possible to observe, with a fluorescence system, residual plaque and calculus that were not easily seen by the naked eye during oral inspection. Thus, the optical technique can potentially improve periodontal screening efforts, especially in patients undergoing periodontal maintenance.

Three-Dimensional Optical Coherence Tomography

NASA Technical Reports Server (NTRS)

Gutin, Mikhail; Wang, Xu-Ming; Gutin, Olga

2009-01-01

Three-dimensional (3D) optical coherence tomography (OCT) is an advanced method of noninvasive infrared imaging of tissues in depth. Heretofore, commercial OCT systems for 3D imaging have been designed principally for external ophthalmological examination. As explained below, such systems have been based on a one-dimensional OCT principle, and in the operation of such a system, 3D imaging is accomplished partly by means of a combination of electronic scanning along the optical (Z) axis and mechanical scanning along the two axes (X and Y) orthogonal to the optical axis. In 3D OCT, 3D imaging involves a form of electronic scanning (without mechanical scanning) along all three axes. Consequently, the need for mechanical adjustment is minimal and the mechanism used to position the OCT probe can be correspondingly more compact. A 3D OCT system also includes a probe of improved design and utilizes advanced signal- processing techniques. Improvements in performance over prior OCT systems include finer resolution, greater speed, and greater depth of field.

Adaptive optics optical coherence tomography with dynamic retinal tracking

PubMed Central

Kocaoglu, Omer P.; Ferguson, R. Daniel; Jonnal, Ravi S.; Liu, Zhuolin; Wang, Qiang; Hammer, Daniel X.; Miller, Donald T.

2014-01-01

Adaptive optics optical coherence tomography (AO-OCT) is a highly sensitive and noninvasive method for three dimensional imaging of the microscopic retina. Like all in vivo retinal imaging techniques, however, it suffers the effects of involuntary eye movements that occur even under normal fixation. In this study we investigated dynamic retinal tracking to measure and correct eye motion at KHz rates for AO-OCT imaging. A customized retina tracking module was integrated into the sample arm of the 2nd-generation Indiana AO-OCT system and images were acquired on three subjects. Analyses were developed based on temporal amplitude and spatial power spectra in conjunction with strip-wise registration to independently measure AO-OCT tracking performance. After optimization of the tracker parameters, the system was found to correct eye movements up to 100 Hz and reduce residual motion to 10 µm root mean square. Between session precision was 33 µm. Performance was limited by tracker-generated noise at high temporal frequencies. PMID:25071963

Automated laser spectrofluorimeter for monitoring of myocardial metabolism

NASA Astrophysics Data System (ADS)

Popov, A. Yu.; Salmin, V. V.; Fursov, A. A.; Stepanenko, A. V.; Sokolovich, A. G.; Salmina, A. B.; Rebenkova, A. A.; Makarov, R. A.; Provorov, A. S.

2006-09-01

Methods of optical biopsy have a series of advantages before other methods of clinical diagnostics. The high accuracy of received results enables registration even small change of concentration of substances, and the opportunity of remote registration makes methods optical biopsy by an optimum means for noninvasive methods of diagnostics in medicine. The method of the fluorescent analysis allows to investigate dynamics of changes of a functional condition of organs and tissue in norm and pathologies, called by the various factors (an inflammation, ischemia, degenerative changes). Bring the results of development of expiremental setup for the laser fluorescent analysis of physiological and functional condition of various organs and tissue of organism. In expiremental setup was used pulse UF nitric laser with length of wave generation = 337 nm. For delivery of radiation to tissue, and, also, collection of a radiation of fluorescence were used various optic fiber scheme. The expiremental setup includes automated tunable monochromator and ADC, receiving a signal from photomultiplier tube. Driving of all blocks and processing of results is realize on IBM-compatible computer with the appropriate software. Was used the synchronous detecting for reducing of a background signal. Myocard at surgical introoperation by an accompanied condition of sharp ischemia was researches on these expiremental setup. Spectrofluorimetric criteria of an estimation of a condition of viscus at peritonitis were development.

Time-resolved transillumination and optical tomography

NASA Astrophysics Data System (ADS)

de Haller, Emmanuel B.

1996-01-01

In response to an invitation by the editor-in-chief, I would like to present the current status of time-domain imaging. With exciting new photon diffusion techniques being developed in the frequency domain and promising optical coherence tomography, time-resolved transillumination is in constant evolution and the subject of passionate discussions during the numerous conferences dedicated to this subject. The purpose of time-resolved optical tomography is to provide noninvasive, high-resolution imaging of the interior of living bodies by the use of nonionizing radiation. Moreover, the use of visible to near-infrared wavelength yields metabolic information. Breast cancer screening is the primary potential application for time-resolved imaging. Neurology and tissue characterization are also possible fields of applications. Time- resolved transillumination and optical tomography should not only improve diagnoses, but the welfare of the patient. As no overview of this technique has yet been presented to my knowledge, this paper briefly describes the various methods enabling time-resolved transillumination and optical tomography. The advantages and disadvantages of these methods, as well as the clinical challenges they face are discussed. Although an analytic and computable model of light transport through tissues is essential for a meaningful interpretation of the transillumination process, this paper will not dwell on the mathematics of photon propagation.

Method and apparatus for nondestructive in vivo measurement of photosynthesis

DOEpatents

Greenbaum, E.

1988-02-22

A device for in situ, nondestructive measurement of photosynthesis in live plants and photosynthetic microorganisms is disclosed which comprises a Clark-type oxygen electrode having a substantially transparent cathode comprised of an optical fiber having a metallic grid microetched onto its front face and sides, an anode, a substantially transparent electrolyte film, and a substantially transparent oxygen permeable membrane. The device is designed to be placed in direct contact with a photosynthetic portion of a living plant, and nondestructive, noninvasive measurement of photosynthetic oxygen production from the plant can be taken by passing light through the fiber-optic cathode, transparent electrolyte and transparent membrane, and onto the plant so that photosynthesis occurs. The oxygen thus produced by the plant is measured polarographically by the electrode. The present invention allows for rapid, nondestructive measurements of photosynthesis in living plants in a manner heretofore impossible using prior art methods. 6 figs.

PRESAGE® as a new calibration method for high intensity focused ultrasound therapy

NASA Astrophysics Data System (ADS)

Costa, M.; McErlean, C.; Rivens, I.; Adamovics, J.; Leach, M. O.; ter Haar, G.; Doran, S. J.

2015-01-01

High Intensity Focused ultrasound (HIFU) is a non-invasive cancer therapy that makes use of the mainly thermal effects of ultrasound to destroy tissue. In order to achieve reliable treatment planning, it is necessary to characterise the ultrasound source (transducer) and to understand how the wave propagates in tissue and the energy deposition in the focal region. This novel exploratory study investigated how HIFU affects PRESAGE®, an optical phantom used for radiotherapy dosimetry, which is potentially a rapid method of calibrating the transducer. Samples, of two different formulations, were exposed to focused ultrasound and imaged using Optical Computed Tomography. First results showed that, PRESAGE® changes colour on ultrasound exposure (darker green regions were observed) with the alterations being related to the acoustic power and sample composition. Future work will involve quantification of these alterations and understanding how to relate them to the mechanisms of action of HIFU.

Method and apparatus for nondestructive in vivo measurement of photosynthesis

DOEpatents

Greenbaum, Elias

1988-01-01

A device for in situ, nondestructive measurement of photosynthesis in live plants and photosynthetic microorganisms is disclosed which comprises a Clark-type oxygen electrode having a substantially transparent cathode comprised of an optical fiber having a metallic grid microetched onto its front face and sides, an anode, a substantially transparent electrolyte film, and a substantially transparent oxygen permeable membrane. The device is designed to be placed in direct contact with a photosynthetic portion of a living plant, and nondestructive, noninvasive measurement of photosynthetic oxygen production from the plant can be taken by passing light through the fiber-optic cathode, transparent electroyte and transparent membrane, and onto the plant so that photosynthesis occurs. The oxygen thus produced by the plant is measured polargraphically by the electrode. The present invention allows for rapid, nondestructive measurements of photosynthesis in living plants in a manner heretofore impossible using prior art methods.

Fourier analysis: from cloaking to imaging

NASA Astrophysics Data System (ADS)

Wu, Kedi; Cheng, Qiluan; Wang, Guo Ping

2016-04-01

Regarding invisibility cloaks as an optical imaging system, we present a Fourier approach to analytically unify both Pendry cloaks and complementary media-based invisibility cloaks into one kind of cloak. By synthesizing different transfer functions, we can construct different devices to realize a series of interesting functions such as hiding objects (events), creating illusions, and performing perfect imaging. In this article, we give a brief review on recent works of applying Fourier approach to analysis invisibility cloaks and optical imaging through scattering layers. We show that, to construct devices to conceal an object, no constructive materials with extreme properties are required, making most, if not all, of the above functions realizable by using naturally occurring materials. As instances, we experimentally verify a method of directionally hiding distant objects and create illusions by using all-dielectric materials, and further demonstrate a non-invasive method of imaging objects completely hidden by scattering layers.

Full scattering profile for detecting physiological tissue properties

NASA Astrophysics Data System (ADS)

Duadi, Hamootal; Fixler, Dror

2017-02-01

Light reflectance and transmission from soft tissue has been utilized in noninvasive clinical measurement devices such as the photoplethysmograph (PPG) and reflectance pulse oximeter. Most methods of near infrared (NIR) spectroscopy focus on the volume reflectance from a semi-infinite sample, while very few measure transmission. We have previously shown that examining the full scattering profile (FSP), which is the angular distribution of exiting photons, provides more comprehensive information when measuring from a cylindrical tissue, such as earlobe, fingertip and pinched tissue. Our hypothesis is that the change in blood vessel diameter is more significant than the change in optical properties. The findings of this work demonstrate a realistic model for optical tissue measurements such as NIR spectroscopy, PPG and pulse oximetery.

Quantifying the vascular response to ischemia with speckle variance optical coherence tomography

PubMed Central

Poole, Kristin M.; McCormack, Devin R.; Patil, Chetan A.; Duvall, Craig L.; Skala, Melissa C.

2014-01-01

Longitudinal monitoring techniques for preclinical models of vascular remodeling are critical to the development of new therapies for pathological conditions such as ischemia and cancer. In models of skeletal muscle ischemia in particular, there is a lack of quantitative, non-invasive and long term assessment of vessel morphology. Here, we have applied speckle variance optical coherence tomography (OCT) methods to quantitatively assess vascular remodeling and growth in a mouse model of peripheral arterial disease. This approach was validated on two different mouse strains known to have disparate rates and abilities of recovering following induction of hind limb ischemia. These results establish the potential for speckle variance OCT as a tool for quantitative, preclinical screening of pro- and anti-angiogenic therapies. PMID:25574425

Real time 3D scanner: investigations and results

NASA Astrophysics Data System (ADS)

Nouri, Taoufik; Pflug, Leopold

1993-12-01

This article presents a concept of reconstruction of 3-D objects using non-invasive and touch loss techniques. The principle of this method is to display parallel interference optical fringes on an object and then to record the object under two angles of view. According to an appropriated treatment one reconstructs the 3-D object even when the object has no symmetrical plan. The 3-D surface data is available immediately in digital form for computer- visualization and for analysis software tools. The optical set-up for recording the 3-D object, the 3-D data extraction and treatment, as well as the reconstruction of the 3-D object are reported and commented on. This application is dedicated for reconstructive/cosmetic surgery, CAD, animation and research purposes.

Influence of hemoglobin on non-invasive optical bilirubin sensing

NASA Astrophysics Data System (ADS)

Jiang, Jingying; Gong, Qiliang; Zou, Da; Xu, Kexin

2012-03-01

Since the abnormal metabolism of bilirubin could lead to diseases in the human body, especially the jaundice which is harmful to neonates. Traditional invasive measurements are difficult to be accepted by people because of pain and infection. Therefore, the real-time and non-invasive measurement of bilirubin is of great significance. However, the accuracy of currently transcutaneous bilirubinometry(TcB) is generally not high enough, and affected by many factors in the human skin, mostly by hemoglobin. In this talk, absorption spectra of hemoglobin and bilirubin have been collected and analyzed, then the Partial Least Squares (PLS) models have been built. By analyzing and comparing the Correlation and Root Mean Square Error of Prediction(RMSEP), the results show that the Correlation of bilirubin solution model is larger than that of the mixture solution added with hemoglobin, and its RMSEP value is smaller than that of mixture solution. Therefore, hemoglobin has influences on the non-invasive optical bilirubin sensing. In next step, it is necessary to investigate how to eliminate the influence.

Noninvasive identification of bladder cancer with subsurface backscattered light

NASA Astrophysics Data System (ADS)

Bigio, Irving J.; Mourant, Judith R.; Boyer, James D.; Johnson, Tamara M.; Shimada, Tsutomu; Conn, Richard L.

1994-05-01

We have developed and are testing early prototypes of an optical biopsy system (OBS) for detection of cancer and other tissue pathologies. The OBS invokes a unique approach to optical diagnosis of tissue pathologies based on the elastic scattering properties, over a wide range of wavelengths, of the microscopic structure of the tissue. Absorption bands in the tissue also add useful complexity to the spectral data collected. The data acquisition and storage/display time with the OBS instrument is approximately 1 second. Thus, in addition to the reduced invasiveness of this technique compared with current state-of- the-art methods, the OBS offers the possibility of impressively faster diagnostic assessment. The OBS employs a small fiber-optic probe that is amendable to use with any endoscope, catheter or hypodermic, or to direct surface examination (e.g., as in skin cancer or cervical cancer). We report here specifically on its potential application in the detection of bladder cancer.

The Choroidal Eye Oximeter - An instrument for measuring oxygen saturation of choroidal blood in vivo

NASA Technical Reports Server (NTRS)

Laing, R. A.; Danisch, L. A.; Young, L. R.

1975-01-01

The Choroidal Eye Oximeter is an electro-optical instrument that noninvasively measures the oxygen saturation of choroidal blood in the back of the human eye by a spectrophotometric method. Since choroidal blood is characteristic of blood which is supplied to the brain, the Choroidal Eye Oximeter can be used to monitor the amount of oxygen which is supplied to the brain under varying external conditions. The instrument consists of two basic systems: the optical system and the electronic system. The optical system produces a suitable bi-chromatic beam of light, reflects this beam from the fundus of the subject's eye, and onto a low-noise photodetector. The electronic system amplifies the weak composite signal from the photodetector, computes the average oxygen saturation from the area of the fundus that was sampled, and displays the value of the computed oxygen saturation on a panel meter.

Imaging of oral pathological tissue using optical coherence tomography

NASA Astrophysics Data System (ADS)

Canjau, Silvana; Todea, Carmen; Sinescu, Cosmin; Duma, Virgil-Florin; Topala, Florin I.; Podoleanu, Adrian G.

2014-01-01

Oral squamous cell carcinoma (OSCC) constitutes 90% of oral cancer. Early detection is a cornerstone to improve survival. Interaction of light with tissues may highlight changes in tissue structure and metabolism. We propose optical coherence tomography (OCT), as a non-invasive diagnosis method, being a new high-resolution optical technique that permits tri-dimensional (3-D), real-time imaging of near surface abnormalities in complex tissues. In this study half of the excisional biopsy was directed to the pathologist and the other half was assigned for OCT investigation. Histopathology validated the results. Areas of OSCC of the buccal mucosa were identified in the OCT images. The elements obserced included extensive epithelial down-growth, the disruption of the basement membrane, with areas of erosion, an epithelial layer that was highly variable in thickness and invasion into the sub-epithelial layers. Therefore, OCT appears to be a highly promising imaging modality.

Quantitative non-invasive intracellular imaging of Plasmodium falciparum infected human erythrocytes

NASA Astrophysics Data System (ADS)

Edward, Kert; Farahi, Faramarz

2014-05-01

Malaria is a virulent pathological condition which results in over a million annual deaths. The parasitic agent Plasmodium falciparum has been extensively studied in connection with this epidemic but much remains unknown about its development inside the red blood cell host. Optical and fluorescence imaging are among the two most common procedures for investigating infected erythrocytes but both require the introduction of exogenous contrast agents. In this letter, we present a procedure for the non-invasive in situ imaging of malaria infected red blood cells. The procedure is based on the utilization of simultaneously acquired quantitative phase and independent topography data to extract intracellular information. Our method allows for the identification of the developmental stages of the parasite and facilitates in situ analysis of the morphological changes associated with the progression of this disease. This information may assist in the development of efficacious treatment therapies for this condition.

Summary of the 2014 Beam-Halo Monitoring Workshop

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fisher, Alan

2015-09-25

Understanding and controlling beam halo is important for high-intensity hadron accelerators, for high-brightness electron linacs, and for low-emittance light sources. This can only be achieved by developing suitable diagnostics. The main challenge faced by such instrumentation is the high dynamic range needed to observe the halo in the presence of an intense core. In addition, measurements must often be made non-invasively. This talk summarizes the one-day workshop on Beam-Halo Monitoring that was held at SLAC on September 19 last year, immediately following IBIC 2014 in Monterey. Workshop presentations described invasive techniques using wires, screens, or crystal collimators, and non-invasive measurementsmore » with gas or scattered electrons. Talks on optical methods showed the close links between observing halo and astronomical problems like observing the solar corona or directly observing a planet orbiting another star.« less

In vivo three-dimensional photoacoustic imaging of the renal vasculature in preclinical rodent models.

PubMed

Ogunlade, Olumide; Connell, John J; Huang, Jennifer L; Zhang, Edward; Lythgoe, Mark F; Long, David A; Beard, Paul

2018-06-01

Noninvasive imaging of the kidney vasculature in preclinical murine models is important for the assessment of renal development, studying diseases and evaluating new therapies but is challenging to achieve using existing imaging modalities. Photoacoustic imaging is a promising new technique that is particularly well suited to visualizing the vasculature and could provide an alternative to existing preclinical imaging methods for studying renal vascular anatomy and function. To investigate this, an all-optical Fabry-Perot-based photoacoustic scanner was used to image the abdominal region of mice. High-resolution three-dimensional, noninvasive, label-free photoacoustic images of the mouse kidney and renal vasculature were acquired in vivo. The scanner was also used to visualize and quantify differences in the vascular architecture of the kidney in vivo due to polycystic kidney disease. This study suggests that photoacoustic imaging could be utilized as a novel preclinical imaging tool for studying the biology of renal disease.

Longitudinal Imaging of Cancer Cell Metastases in Two Preclinical Models: A Correlation of Noninvasive Imaging to Histopathology

PubMed Central

Adiseshaiah, Pavan P.; Patel, Nimit L.; Ileva, Lilia V.; Kalen, Joseph D.; Haines, Diana C.; McNeil, Scott E.

2014-01-01

Metastatic spread is the leading cause of death from cancer. Early detection of cancer at primary and metastatic sites by noninvasive imaging modalities would be beneficial for both therapeutic intervention and disease management. Noninvasive imaging modalities such as bioluminescence (optical), positron emission tomography (PET)/X-ray computed tomography (CT), and magnetic resonance imaging (MRI) can provide complementary information and accurately measure tumor growth as confirmed by histopathology. Methods. We validated two metastatic tumor models, MDA-MD-231-Luc and B16-F10-Luc intravenously injected, and 4T1-Luc cells orthotopically implanted into the mammary fat pad. Longitudinal whole body bioluminescence imaging (BLI) evaluated metastasis, and tumor burden of the melanoma cell line (B16-F10-Luc) was correlated with (PET)/CT and MRI. In addition, ex vivo imaging evaluated metastasis in relevant organs and histopathological analysis was used to confirm imaging. Results. BLI revealed successful colonization of cancer cells in both metastatic tumor models over a 4-week period. Furthermore, lung metastasis of B16-F10-Luc cells imaged by PET/CT at week four showed a strong correlation (R 2 = 0.9) with histopathology. The presence and degree of metastasis as determined by imaging correlated (R 2 = 0.7) well with histopathology findings. Conclusions. We validated two metastatic tumor models by longitudinal noninvasive imaging with good histopathology correlation. PMID:24724022

Effects of Prone Position and Positive End-Expiratory Pressure on Noninvasive Estimators of ICP: A Pilot Study.

PubMed

Robba, Chiara; Bragazzi, Nicola Luigi; Bertuccio, Alessandro; Cardim, Danilo; Donnelly, Joseph; Sekhon, Mypinder; Lavinio, Andrea; Duane, Derek; Burnstein, Rowan; Matta, Basil; Bacigaluppi, Susanna; Lattuada, Marco; Czosnyka, Marek

2017-07-01

Prone positioning and positive end-expiratory pressure can improve pulmonary gas exchange and respiratory mechanics. However, they may be associated with the development of intracranial hypertension. Intracranial pressure (ICP) can be noninvasively estimated from the sonographic measurement of the optic nerve sheath diameter (ONSD) and from the transcranial Doppler analysis of the pulsatility (ICPPI) and the diastolic component (ICPFVd) of the velocity waveform. The effect of the prone positioning and positive end-expiratory pressure on ONSD, ICPFVd, and ICPPI was assessed in a prospective study of 30 patients undergoing spine surgery. One-way repeated measures analysis of variance, fixed-effect multivariate regression models, and receiver operating characteristic analyses were used to analyze numerical data. The mean values of ONSD, ICPFVd, and ICPPI significantly increased after change from supine to prone position. Receiver operating characteristic analyses demonstrated that, among the noninvasive methods, the mean ONSD measure had the greatest area under the curve signifying it is the most effective in distinguishing a hypothetical change in ICP between supine and prone positioning (0.86±0.034 [0.79 to 0.92]). A cutoff of 0.43 cm was found to be a best separator of ONSD value between supine and prone with a specificity of 75.0 and a sensitivity of 86.7. Noninvasive ICP estimation may be useful in patients at risk of developing intracranial hypertension who require prone positioning.

In vivo assessment of the structure of skin microcirculation by reflectance confocal-laser-scanning microscopy

NASA Astrophysics Data System (ADS)

Sugata, Keiichi; Osanai, Osamu; Kawada, Hiromitsu

2012-02-01

One of the major roles of the skin microcirculation is to supply oxygen and nutrition to the surrounding tissue. Regardless of the close relationship between the microcirculation and the surrounding tissue, there are few non-invasive methods that can evaluate both the microcirculation and its surrounding tissue at the same site. We visualized microcapillary plexus structures in human skin using in vivo reflectance confocal-laser-scanning microscopy (CLSM), Vivascope 3000® (Lucid Inc., USA) and Image J software (National Institutes of Health, USA) for video image processing. CLSM is a non-invasive technique that can visualize the internal structure of the skin at the cellular level. In addition to internal morphological information such as the extracellular matrix, our method reveals capillary structures up to the depth of the subpapillary plexus at the same site without the need for additional optical systems. Video images at specific depths of the inner forearm skin were recorded. By creating frame-to-frame difference images from the video images using off-line video image processing, we obtained images that emphasize the brightness depending on changes of intensity coming from the movement of blood cells. Merging images from different depths of the skin elucidates the 3-dimensional fine line-structure of the microcirculation. Overall our results show the feasibility of a non-invasive, high-resolution imaging technique to characterize the skin microcirculation and the surrounding tissue.

Optical Fluorescent Imaging to Monitor Temporal Effects of Microbubble-Mediated Ultrasound Therapy

PubMed Central

Sorace, Anna G.; Saini, Reshu; Rosenthal, Eben; Warram, Jason M.; Zinn, Kurt R.; Hoyt, Kenneth

2013-01-01

Microbubble-mediated ultrasound therapy can noninvasively enhance drug delivery to localized regions in the body. This technique can be beneficial in cancer therapy, but currently there are limitations to tracking the therapeutic effects. The purpose of this experiment was to investigate the potential of fluorescent imaging for monitoring the temporal effects of microbubble-mediated ultrasound therapy. Mice were implanted with 2LMP breast cancer cells. The animals underwent microbubble-mediated ultrasound therapy in the presence of Cy5.5 fluorescent-labeled IgG antibody (large molecule) or Cy5.5 dye (small molecule) and microbubble contrast agents. Control animals were administered fluorescent molecules only. Animals were transiently imaged in vivo at 1, 10, 30, and 60 min post therapy using a small animal optical imaging system. Tumors were excised and analyzed ex vivo. Tumors were homogenized and emulsion imaged for Cy5.5 fluorescence. Monitoring in vivo results showed significant influx of dye into the tumor (p < 0.05) using the small molecule, but not in the large molecule group (p > 0.05). However, after tumor emulsion, significantly higher dye concentration was detected in therapy group tumors for both small and large molecule groups in comparison to their control counterparts (p < 0.01). This paper explores a noninvasive optical imaging method for monitoring the effects of microbubble-mediated ultrasound therapy in a cancer model. It provides temporal information following the process of increasing extravasation of molecules into target tumors. PMID:23357902

Optical fluorescent imaging to monitor temporal effects of microbubble-mediated ultrasound therapy.

PubMed

Sorace, Anna G; Saini, Reshu; Rosenthal, Eben; Warram, Jason M; Zinn, Kurt R; Hoyt, Kenneth

2013-02-01

Microbubble-mediated ultrasound therapy can noninvasively enhance drug delivery to localized regions in the body. This technique can be beneficial in cancer therapy, but currently there are limitations to tracking the therapeutic effects. The purpose of this experiment was to investigate the potential of fluorescent imaging for monitoring the temporal effects of microbubble-mediated ultrasound therapy. Mice were implanted with 2LMP breast cancer cells. The animals underwent microbubble-mediated ultrasound therapy in the presence of Cy5.5 fluorescent-labeled IgG antibody (large molecule) or Cy5.5 dye (small molecule) and microbubble contrast agents. Control animals were administered fluorescent molecules only. Animals were transiently imaged in vivo at 1, 10, 30, and 60 min post therapy using a small animal optical imaging system. Tumors were excised and analyzed ex vivo. Tumors were homogenized and emulsion imaged for Cy5.5 fluorescence. Monitoring in vivo results showed significant influx of dye into the tumor (p < 0.05) using the small molecule, but not in the large molecule group (p > 0.05). However, after tumor emulsion, significantly higher dye concentration was detected in therapy group tumors for both small and large molecule groups in comparison to their control counterparts (p <0.01). This paper explores a noninvasive optical imaging method for monitoring the effects of microbubble-mediated ultrasound therapy in a cancer model. It provides temporal information following the process of increasing extravasation of molecules into target tumors.

Functional imaging and assessment of the glucose diffusion rate in epithelial tissues in optical coherence tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Larin, K V; Tuchin, V V

2008-06-30

Functional imaging, monitoring and quantitative description of glucose diffusion in epithelial and underlying stromal tissues in vivo and controlling of the optical properties of tissues are extremely important for many biomedical applications including the development of noninvasive or minimally invasive glucose sensors as well as for therapy and diagnostics of various diseases, such as cancer, diabetic retinopathy, and glaucoma. Recent progress in the development of a noninvasive molecular diffusion biosensor based on optical coherence tomography (OCT) is described. The diffusion of glucose was studied in several epithelial tissues both in vitro and in vivo. Because OCT provides depth-resolved imaging ofmore » tissues with high in-depth resolution, the glucose diffusion is described not only as a function of time but also as a function of depth. (special issue devoted to application of laser technologies in biophotonics and biomedical studies)« less

Measurements of the thermal coefficient of optical attenuation at different depth regions of in vivo human skins using optical coherence tomography: a pilot study

PubMed Central

Su, Ya; Yao, X. Steve; Li, Zhihong; Meng, Zhuo; Liu, Tiegen; Wang, Longzhi

2015-01-01

We present detailed measurement results of optical attenuation’s thermal coefficients (referenced to the temperature of the skin surface) in different depth regions of in vivo human forearm skins using optical coherence tomography (OCT). We first design a temperature control module with an integrated optical probe to precisely control the surface temperature of a section of human skin. We propose a method of using the correlation map to identify regions in the skin having strong correlations with the surface temperature of the skin and find that the attenuation coefficient in these regions closely follows the variation of the surface temperature without any hysteresis. We observe a negative thermal coefficient of attenuation in the epidermis. While in dermis, the slope signs of the thermal coefficient of attenuation are different at different depth regions for a particular subject, however, the depth regions with a positive (or negative) slope are different in different subjects. We further find that the magnitude of the thermal coefficient of attenuation coefficient is greater in epidermis than in dermis. We believe the knowledge of such thermal properties of skins is important for several noninvasive diagnostic applications, such as OCT glucose monitoring, and the method demonstrated in this paper is effective in studying the optical and biological properties in different regions of skin. PMID:25780740

Extending calibration-free force measurements to optically-trapped rod-shaped samples

PubMed Central

Català, Frederic; Marsà, Ferran; Montes-Usategui, Mario; Farré, Arnau; Martín-Badosa, Estela

2017-01-01

Optical trapping has become an optimal choice for biological research at the microscale due to its non-invasive performance and accessibility for quantitative studies, especially on the forces involved in biological processes. However, reliable force measurements depend on the calibration of the optical traps, which is different for each experiment and hence requires high control of the local variables, especially of the trapped object geometry. Many biological samples have an elongated, rod-like shape, such as chromosomes, intracellular organelles (e.g., peroxisomes), membrane tubules, certain microalgae, and a wide variety of bacteria and parasites. This type of samples often requires several optical traps to stabilize and orient them in the correct spatial direction, making it more difficult to determine the total force applied. Here, we manipulate glass microcylinders with holographic optical tweezers and show the accurate measurement of drag forces by calibration-free direct detection of beam momentum. The agreement between our results and slender-body hydrodynamic theoretical calculations indicates potential for this force-sensing method in studying protracted, rod-shaped specimens. PMID:28220855

Elucidation of the role of biological factors and device design in cerebral NIRS using an in vivo hematoma model based on high-intensity focused ultrasound

NASA Astrophysics Data System (ADS)

Wang, Jianting; Huang, Stanley; Myers, Matthew; Chen, Yu; Welle, Cristin; Pfefer, Joshua

2016-03-01

Near-Infrared Spectroscopy (NIRS) is an emerging medical countermeasure for rapid, field detection of hematomas caused by traumatic brain injury (TBI). Bench and animal tests to determine NIRS sensitivity and specificity are needed. However, current animal models involving non-invasively induced, localized neural damage are limited. We investigated an in vivo murine hematoma model in which cerebral hemorrhage was induced noninvasively by high-intensity focused ultrasound (HIFU) with calibrated positioning and parameters. To characterize the morphology of induced hematomas, we used skull-intact histological evaluation. A multi-wavelength fiber-optic NIRS system with three source-detector separation distances was used to detect hematoma A 1.1 MHz transducer produced consistent small-to-medium hematoma localized to a single hemisphere, along with bruising of the scalp, with a low mortality rate. A 220 kHz transducer produced larger, more diffuse hematomas, with higher variability in size and a correspondingly higher mortality rate. No skin bruising or blood accumulation between the skin and skull was observed following injury application with the 220 kHz transducer. Histological analysis showed higher sensitivity for larger hematomas (>4x4 mm2). NIRS optical density change after HIFU was able to detect all hematomas, with sensitivity dependent on wavelength and separation distance. While improvements in methods for validating cerebral blood distribution are needed, the HIFU hematoma model provided useful insights that will inform development of biologically relevant, performance test methods for cerebral NIRS systems.

Monitoring of tissue optical properties using OCT: application for blood glucose analysis

NASA Astrophysics Data System (ADS)

Larin, Kirill V.; Eledrisi, Mohsen S.; Ashitkov, Taras V.; Motamedi, Massoud; Esenaliev, Rinat O.

2002-07-01

Noninvasive monitoring of tissue optical properties in real time could significantly improve diagnostics and management of various diseases. Recently we proposed to use high- resolution Optical Coherence Tomography (OCT) technique for measurement of tissue scattering coefficient at the depth of up to 1mm. Our pilot studies performed in vitro and in vivo demonstrated that measurement of tissue scattering with this technique can potentially be applied for noninvasive monitoring of blood glucose concentration. High resolution and coherent photon detection of the OCT technique allowed detection of glucose-induced changes in the scattering coefficient. In this paper we report results of in vivo studies performed in dog, New Zealand rabbits, and first human subjects. OCT system with the wavelength of 1300 nm was used in our experiments. OCT signal slope was measured and compared with actual blood glucose concentration. Bolus glucose injections and glucose clamping administrations were used in animal studies. OCT signals were recorded form human subjects during oral glucose tolerance test. Results obtained form both animal and human studies show good correlation between slope of the OCT signals and actual blood glucose concentration measured using standard glucometesr. Sensitivity and accuracy of blood glucose concentrations monitoring with the OCT is discussed. Obtained result suggest that OCT is a promising technique for noninvasive monitoring of tissue analytes including glucose.

Structured illumination diffuse optical tomography for noninvasive functional neuroimaging in mice.

PubMed

Reisman, Matthew D; Markow, Zachary E; Bauer, Adam Q; Culver, Joseph P

2017-04-01

Optical intrinsic signal (OIS) imaging has been a powerful tool for capturing functional brain hemodynamics in rodents. Recent wide field-of-view implementations of OIS have provided efficient maps of functional connectivity from spontaneous brain activity in mice. However, OIS requires scalp retraction and is limited to superficial cortical tissues. Diffuse optical tomography (DOT) techniques provide noninvasive imaging, but previous DOT systems for rodent neuroimaging have been limited either by sparse spatial sampling or by slow speed. Here, we develop a DOT system with asymmetric source-detector sampling that combines the high-density spatial sampling (0.4 mm) detection of a scientific complementary metal-oxide-semiconductor camera with the rapid (2 Hz) imaging of a few ([Formula: see text]) structured illumination (SI) patterns. Analysis techniques are developed to take advantage of the system's flexibility and optimize trade-offs among spatial sampling, imaging speed, and signal-to-noise ratio. An effective source-detector separation for the SI patterns was developed and compared with light intensity for a quantitative assessment of data quality. The light fall-off versus effective distance was also used for in situ empirical optimization of our light model. We demonstrated the feasibility of this technique by noninvasively mapping the functional response in the somatosensory cortex of the mouse following electrical stimulation of the forepaw.

Stochastic speckle noise compensation in optical coherence tomography using non-stationary spline-based speckle noise modelling.

PubMed

Cameron, Andrew; Lui, Dorothy; Boroomand, Ameneh; Glaister, Jeffrey; Wong, Alexander; Bizheva, Kostadinka

2013-01-01

Optical coherence tomography (OCT) allows for non-invasive 3D visualization of biological tissue at cellular level resolution. Often hindered by speckle noise, the visualization of important biological tissue details in OCT that can aid disease diagnosis can be improved by speckle noise compensation. A challenge with handling speckle noise is its inherent non-stationary nature, where the underlying noise characteristics vary with the spatial location. In this study, an innovative speckle noise compensation method is presented for handling the non-stationary traits of speckle noise in OCT imagery. The proposed approach centers on a non-stationary spline-based speckle noise modeling strategy to characterize the speckle noise. The novel method was applied to ultra high-resolution OCT (UHROCT) images of the human retina and corneo-scleral limbus acquired in-vivo that vary in tissue structure and optical properties. Test results showed improved performance of the proposed novel algorithm compared to a number of previously published speckle noise compensation approaches in terms of higher signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and better overall visual assessment.

Stochastic speckle noise compensation in optical coherence tomography using non-stationary spline-based speckle noise modelling

PubMed Central

Cameron, Andrew; Lui, Dorothy; Boroomand, Ameneh; Glaister, Jeffrey; Wong, Alexander; Bizheva, Kostadinka

2013-01-01

Optical coherence tomography (OCT) allows for non-invasive 3D visualization of biological tissue at cellular level resolution. Often hindered by speckle noise, the visualization of important biological tissue details in OCT that can aid disease diagnosis can be improved by speckle noise compensation. A challenge with handling speckle noise is its inherent non-stationary nature, where the underlying noise characteristics vary with the spatial location. In this study, an innovative speckle noise compensation method is presented for handling the non-stationary traits of speckle noise in OCT imagery. The proposed approach centers on a non-stationary spline-based speckle noise modeling strategy to characterize the speckle noise. The novel method was applied to ultra high-resolution OCT (UHROCT) images of the human retina and corneo-scleral limbus acquired in-vivo that vary in tissue structure and optical properties. Test results showed improved performance of the proposed novel algorithm compared to a number of previously published speckle noise compensation approaches in terms of higher signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR) and better overall visual assessment. PMID:24049697

Combining Whispering-Gallery Mode Optical Biosensors with Microfluidics for Real-Time Detection of Protein Secretion from Living Cells in Complex Media.

PubMed

Chen, Ying-Jen; Schoeler, Ulrike; Huang, Chung-Hsuan Benjamin; Vollmer, Frank

2018-05-01

The noninvasive monitoring of protein secretion of cells responding to drug treatment is an effective and essential tool in latest drug development and for cytotoxicity assays. In this work, a surface functionalization method is demonstrated for specific detection of protein released from cells and a platform that integrates highly sensitive optical devices, called whispering-gallery mode biosensors, with precise microfluidics control to achieve label-free and real-time detection. Cell biomarker release is measured in real time and with nanomolar sensitivity. The surface functionalization method allows for antibodies to be immobilized on the surface for specific detection, while the microfluidics system enables detection in a continuous flow with a negligible compromise between sensitivity and flow control over stabilization and mixing. Cytochrome c detection is used to illustrate the merits of the system. Jurkat cells are treated with the toxin staurosporine to trigger cell apoptosis and cytochrome c released into the cell culture medium is monitored via the newly invented optical microfluidic platform. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

In vivo non-invasive monitoring of collagen remodelling by two-photon microscopy after micro-ablative fractional laser resurfacing.

PubMed

Cicchi, Riccardo; Kapsokalyvas, Dimitrios; Troiano, Michela; Campolmi, Piero; Morini, Cristiano; Massi, Daniela; Cannarozzo, Giovanni; Lotti, Torello; Pavone, Francesco Saverio

2014-11-01

Non-linear optical microscopy is becoming popular as a non-invasive in vivo imaging modality in dermatology. In this study, combined TPF and SHG microscopy were used to monitor collagen remodelling in vivo after micro-ablative fractional laser resurfacing. Papillary dermis of living subjects, covering a wide age range, was imaged immediately before and forty days after treatment. A qualitative visual examination of acquired images demonstrated an age-dependent remodelling effect on collagen. Additional quantitative analysis of new collagen production was performed by means of two image analysis methods. A higher increase in SHG to TPF ratio, corresponding to a stronger treatment effectiveness, was found in older subjects, whereas the effect was found to be negligible in young, and minimal in middle age subjects. Analysis of collagen images also showed a dependence of the treatment effectiveness with age but with controversial results. While the diagnostic potential of in vivo multiphoton microscopy has already been demonstrated for skin cancer and other skin diseases, here we first successfully explore its potential use for a non-invasive follow-up of a laser-based treatment. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Noninvasive observation of skeletal muscle contraction using near-infrared time-resolved reflectance and diffusing-wave spectroscopy

NASA Astrophysics Data System (ADS)

Belau, Markus; Ninck, Markus; Hering, Gernot; Spinelli, Lorenzo; Contini, Davide; Torricelli, Alessandro; Gisler, Thomas

2010-09-01

We introduce a method for noninvasively measuring muscle contraction in vivo, based on near-infrared diffusing-wave spectroscopy (DWS). The method exploits the information about time-dependent shear motions within the contracting muscle that are contained in the temporal autocorrelation function g(1)(τ,t) of the multiply scattered light field measured as a function of lag time, τ, and time after stimulus, t. The analysis of g(1)(τ,t) measured on the human M. biceps brachii during repetitive electrical stimulation, using optical properties measured with time-resolved reflectance spectroscopy, shows that the tissue dynamics giving rise to the speckle fluctuations can be described by a combination of diffusion and shearing. The evolution of the tissue Cauchy strain e(t) shows a strong correlation with the force, indicating that a significant part of the shear observed with DWS is due to muscle contraction. The evolution of the DWS decay time shows quantitative differences between the M. biceps brachii and the M. gastrocnemius, suggesting that DWS allows to discriminate contraction of fast- and slow-twitch muscle fibers.

Deep-tissue temperature mapping by multi-illumination photoacoustic tomography aided by a diffusion optical model: a numerical study

NASA Astrophysics Data System (ADS)

Zhou, Yuan; Tang, Eric; Luo, Jianwen; Yao, Junjie

2018-01-01

Temperature mapping during thermotherapy can help precisely control the heating process, both temporally and spatially, to efficiently kill the tumor cells and prevent the healthy tissues from heating damage. Photoacoustic tomography (PAT) has been used for noninvasive temperature mapping with high sensitivity, based on the linear correlation between the tissue's Grüneisen parameter and temperature. However, limited by the tissue's unknown optical properties and thus the optical fluence at depths beyond the optical diffusion limit, the reported PAT thermometry usually takes a ratiometric measurement at different temperatures and thus cannot provide absolute measurements. Moreover, ratiometric measurement over time at different temperatures has to assume that the tissue's optical properties do not change with temperatures, which is usually not valid due to the temperature-induced hemodynamic changes. We propose an optical-diffusion-model-enhanced PAT temperature mapping that can obtain the absolute temperature distribution in deep tissue, without the need of multiple measurements at different temperatures. Based on the initial acoustic pressure reconstructed from multi-illumination photoacoustic signals, both the local optical fluence and the optical parameters including absorption and scattering coefficients are first estimated by the optical-diffusion model, then the temperature distribution is obtained from the reconstructed Grüneisen parameters. We have developed a mathematic model for the multi-illumination PAT of absolute temperatures, and our two-dimensional numerical simulations have shown the feasibility of this new method. The proposed absolute temperature mapping method may set the technical foundation for better temperature control in deep tissue in thermotherapy.

A hyaluronic acid nanogel for photo-chemo theranostics of lung cancer with simultaneous light-responsive controlled release of doxorubicin

NASA Astrophysics Data System (ADS)

Khatun, Zehedina; Nurunnabi, Md; Nafiujjaman, Md; Reeck, Gerald R.; Khan, Haseeb A.; Cho, Kwang Jae; Lee, Yong-Kyu

2015-06-01

The combined delivery of photo- and chemo-therapeutic agents is an emerging strategy to overcome drug resistance in treating cancer, and controlled light-responsive drug release is a proven tactic to produce a continuous therapeutic effect for a prolonged duration. Here, a combination of light-responsive graphene, chemo-agent doxorubicin and pH-sensitive disulfide-bond linked hyaluronic acid form a nanogel (called a graphene-doxorubicin conjugate in a hyaluronic acid nanogel) that exerts an activity with multiple effects: thermo and chemotherapeutic, real-time noninvasive imaging, and light-glutathione-responsive controlled drug release. The nanogel is mono-dispersed with an average diameter of 120 nm as observed by using TEM and a hydrodynamic size analyzer. It has excellent photo-luminescence properties and good stability in buffer and serum solutions. Graphene itself, being photoluminescent, can be considered an optical imaging contrast agent as well as a heat source when excited by laser irradiation. Thus the nanogel shows simultaneous thermo-chemotherapeutic effects on noninvasive optical imaging. We have also found that irradiation enhances the release of doxorubicin in a controlled manner. This release synergizes therapeutic activity of the nanogel in killing tumor cells. Our findings demonstrate that the graphene-doxorubicin conjugate in the hyaluronic acid nanogel is very effective in killing the human lung cancer cell line (A549) with limited toxicity in the non-cancerous cell line (MDCK).The combined delivery of photo- and chemo-therapeutic agents is an emerging strategy to overcome drug resistance in treating cancer, and controlled light-responsive drug release is a proven tactic to produce a continuous therapeutic effect for a prolonged duration. Here, a combination of light-responsive graphene, chemo-agent doxorubicin and pH-sensitive disulfide-bond linked hyaluronic acid form a nanogel (called a graphene-doxorubicin conjugate in a hyaluronic acid nanogel) that exerts an activity with multiple effects: thermo and chemotherapeutic, real-time noninvasive imaging, and light-glutathione-responsive controlled drug release. The nanogel is mono-dispersed with an average diameter of 120 nm as observed by using TEM and a hydrodynamic size analyzer. It has excellent photo-luminescence properties and good stability in buffer and serum solutions. Graphene itself, being photoluminescent, can be considered an optical imaging contrast agent as well as a heat source when excited by laser irradiation. Thus the nanogel shows simultaneous thermo-chemotherapeutic effects on noninvasive optical imaging. We have also found that irradiation enhances the release of doxorubicin in a controlled manner. This release synergizes therapeutic activity of the nanogel in killing tumor cells. Our findings demonstrate that the graphene-doxorubicin conjugate in the hyaluronic acid nanogel is very effective in killing the human lung cancer cell line (A549) with limited toxicity in the non-cancerous cell line (MDCK). Electronic supplementary information (ESI) available: In vitro stability study method and results, FT-IR data, optical properties and thermal stability (TGA and DTA), cell image and in vivo optical image and histological images. See DOI: 10.1039/c5nr01075f

Neuro-ophthalmological presentation of non-invasive Aspergillus sinus disease in the non-immunocompromised host.

PubMed Central

Brown, P; Demaerel, P; McNaught, A; Revesz, T; Graham, E; Kendall, B E; Plant, G

1994-01-01

Two cases of non-invasive aspergillosis of the nose and paranasal sinuses are described. The first presented with left proptosis and ophthalmoplegia. Imaging and histology showed a maxillary sinus aspergilloma. The second case presented as a compressive optic neuropathy and histology showed allergic aspergillus sinusitis. The pathological distinction between invasive and non-invasive forms of aspergillus sinusitis is important as in invasive aspergillosis surgical treatment is most effectively combined with systemic antifungal treatment, whereas in aspergilloma of the paranasal sinuses surgical drainage of the sinuses alone is usually sufficient, and in allergic aspergillus sinusitis surgery is best combined with systemic or topical steroids. The distinction between invasive and non-invasive forms is particularly important as both may present with cranial neuropathies. Images PMID:8126516

A Phonocardiographic-Based Fiber-Optic Sensor and Adaptive Filtering System for Noninvasive Continuous Fetal Heart Rate Monitoring.

PubMed

Martinek, Radek; Nedoma, Jan; Fajkus, Marcel; Kahankova, Radana; Konecny, Jaromir; Janku, Petr; Kepak, Stanislav; Bilik, Petr; Nazeran, Homer

2017-04-18

This paper focuses on the design, realization, and verification of a novel phonocardiographic- based fiber-optic sensor and adaptive signal processing system for noninvasive continuous fetal heart rate (fHR) monitoring. Our proposed system utilizes two Mach-Zehnder interferometeric sensors. Based on the analysis of real measurement data, we developed a simplified dynamic model for the generation and distribution of heart sounds throughout the human body. Building on this signal model, we then designed, implemented, and verified our adaptive signal processing system by implementing two stochastic gradient-based algorithms: the Least Mean Square Algorithm (LMS), and the Normalized Least Mean Square (NLMS) Algorithm. With this system we were able to extract the fHR information from high quality fetal phonocardiograms (fPCGs), filtered from abdominal maternal phonocardiograms (mPCGs) by performing fPCG signal peak detection. Common signal processing methods such as linear filtering, signal subtraction, and others could not be used for this purpose as fPCG and mPCG signals share overlapping frequency spectra. The performance of the adaptive system was evaluated by using both qualitative (gynecological studies) and quantitative measures such as: Signal-to-Noise Ratio-SNR, Root Mean Square Error-RMSE, Sensitivity-S+, and Positive Predictive Value-PPV.

A Phonocardiographic-Based Fiber-Optic Sensor and Adaptive Filtering System for Noninvasive Continuous Fetal Heart Rate Monitoring

PubMed Central

Martinek, Radek; Nedoma, Jan; Fajkus, Marcel; Kahankova, Radana; Konecny, Jaromir; Janku, Petr; Kepak, Stanislav; Bilik, Petr; Nazeran, Homer

2017-01-01

This paper focuses on the design, realization, and verification of a novel phonocardiographic- based fiber-optic sensor and adaptive signal processing system for noninvasive continuous fetal heart rate (fHR) monitoring. Our proposed system utilizes two Mach-Zehnder interferometeric sensors. Based on the analysis of real measurement data, we developed a simplified dynamic model for the generation and distribution of heart sounds throughout the human body. Building on this signal model, we then designed, implemented, and verified our adaptive signal processing system by implementing two stochastic gradient-based algorithms: the Least Mean Square Algorithm (LMS), and the Normalized Least Mean Square (NLMS) Algorithm. With this system we were able to extract the fHR information from high quality fetal phonocardiograms (fPCGs), filtered from abdominal maternal phonocardiograms (mPCGs) by performing fPCG signal peak detection. Common signal processing methods such as linear filtering, signal subtraction, and others could not be used for this purpose as fPCG and mPCG signals share overlapping frequency spectra. The performance of the adaptive system was evaluated by using both qualitative (gynecological studies) and quantitative measures such as: Signal-to-Noise Ratio—SNR, Root Mean Square Error—RMSE, Sensitivity—S+, and Positive Predictive Value—PPV. PMID:28420215

Design of a portable noninvasive photoacoustic glucose monitoring system integrated laser diode excitation with annular array detection

NASA Astrophysics Data System (ADS)

Zeng, Lvming; Liu, Guodong; Yang, Diwu; Ren, Zhong; Huang, Zhen

2008-12-01

A near-infrared photoacoustic glucose monitoring system, which is integrated dual-wavelength pulsed laser diode excitation with eight-element planar annular array detection technique, is designed and fabricated during this study. It has the characteristics of nonivasive, inexpensive, portable, accurate location, and high signal-to-noise ratio. In the system, the exciting source is based on two laser diodes with wavelengths of 905 nm and 1550 nm, respectively, with optical pulse energy of 20 μJ and 6 μJ. The laser beam is optically focused and jointly projected to a confocal point with a diameter of 0.7 mm approximately. A 7.5 MHz 8-element annular array transducer with a hollow structure is machined to capture photoacoustic signal in backward mode. The captured signals excitated from blood glucose are processed with a synthetic focusing algorithm to obtain high signal-to-noise ratio and accurate location over a range of axial detection depth. The custom-made transducer with equal area elements is coaxially collimated with the laser source to improve the photoacoustic excite/receive efficiency. In the paper, we introduce the photoacoustic theory, receive/process technique, and design method of the portable noninvasive photoacoustic glucose monitoring system, which can potentially be developed as a powerful diagnosis and treatment tool for diabetes mellitus.

Blood flow and oxygenation changes due to low-frequency repetitive transcranial magnetic stimulation of the cerebral cortex

NASA Astrophysics Data System (ADS)

Mesquita, Rickson C.; Faseyitan, Olufunsho K.; Turkeltaub, Peter E.; Buckley, Erin M.; Thomas, Amy; Kim, Meeri N.; Durduran, Turgut; Greenberg, Joel H.; Detre, John A.; Yodh, Arjun G.; Hamilton, Roy H.

2013-06-01

Transcranial magnetic stimulation (TMS) modulates processing in the human brain and is therefore of interest as a treatment modality for neurologic conditions. During TMS administration, an electric current passing through a coil on the scalp creates a rapidly varying magnetic field that induces currents in the cerebral cortex. The effects of low-frequency (1 Hz), repetitive TMS (rTMS) on motor cortex cerebral blood flow (CBF) and tissue oxygenation in seven healthy adults, during/after 20 min stimulation, is reported. Noninvasive optical methods are employed: diffuse correlation spectroscopy (DCS) for blood flow and diffuse optical spectroscopy (DOS) for hemoglobin concentrations. A significant increase in median CBF (33%) on the side ipsilateral to stimulation was observed during rTMS and persisted after discontinuation. The measured hemodynamic parameter variations enabled computation of relative changes in cerebral metabolic rate of oxygen consumption during rTMS, which increased significantly (28%) in the stimulated hemisphere. By contrast, hemodynamic changes from baseline were not observed contralateral to rTMS administration (all parameters, p>0.29). In total, these findings provide new information about hemodynamic/metabolic responses to low-frequency rTMS and, importantly, demonstrate the feasibility of DCS/DOS for noninvasive monitoring of TMS-induced physiologic effects.

An overview of methods to mitigate artifacts in optical coherence tomography imaging of the skin.

PubMed

Adabi, Saba; Fotouhi, Audrey; Xu, Qiuyun; Daveluy, Steve; Mehregan, Darius; Podoleanu, Adrian; Nasiriavanaki, Mohammadreza

2018-05-01

Optical coherence tomography (OCT) of skin delivers three-dimensional images of tissue microstructures. Although OCT imaging offers a promising high-resolution modality, OCT images suffer from some artifacts that lead to misinterpretation of tissue structures. Therefore, an overview of methods to mitigate artifacts in OCT imaging of the skin is of paramount importance. Speckle, intensity decay, and blurring are three major artifacts in OCT images. Speckle is due to the low coherent light source used in the configuration of OCT. Intensity decay is a deterioration of light with respect to depth, and blurring is the consequence of deficiencies of optical components. Two speckle reduction methods (one based on artificial neural network and one based on spatial compounding), an attenuation compensation algorithm (based on Beer-Lambert law) and a deblurring procedure (using deconvolution), are described. Moreover, optical properties extraction algorithm based on extended Huygens-Fresnel (EHF) principle to obtain some additional information from OCT images are discussed. In this short overview, we summarize some of the image enhancement algorithms for OCT images which address the abovementioned artifacts. The results showed a significant improvement in the visibility of the clinically relevant features in the images. The quality improvement was evaluated using several numerical assessment measures. Clinical dermatologists benefit from using these image enhancement algorithms to improve OCT diagnosis and essentially function as a noninvasive optical biopsy. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

In vitro glucose measurement using tunable mid-infrared laser spectroscopy combined with fiber-optic sensor

PubMed Central

Yu, Songlin; Li, Dachao; Chong, Hao; Sun, Changyue; Yu, Haixia; Xu, Kexin

2013-01-01

Because mid-infrared (mid-IR) spectroscopy is not a promising method to noninvasively measure glucose in vivo, a method for minimally invasive high-precision glucose determination in vivo by mid-IR laser spectroscopy combined with a tunable laser source and small fiber-optic attenuated total reflection (ATR) sensor is introduced. The potential of this method was evaluated in vitro. This research presents a mid-infrared tunable laser with a broad emission spectrum band of 9.19 to 9.77μm(1024~1088 cm−1) and proposes a method to control and stabilize the laser emission wavelength and power. Moreover, several fiber-optic ATR sensors were fabricated and investigated to determine glucose in combination with the tunable laser source, and the effective sensing optical length of these sensors was determined for the first time. In addition, the sensitivity of this system was four times that of a Fourier transform infrared (FT-IR) spectrometer. The noise-equivalent concentration (NEC) of this laser measurement system was as low as 3.8 mg/dL, which is among the most precise glucose measurements using mid-infrared spectroscopy. Furthermore, a partial least-squares regression and Clarke error grid were used to quantify the predictability and evaluate the prediction accuracy of glucose concentration in the range of 5 to 500 mg/dL (physiologically relevant range: 30~400 mg/dL). The experimental results were clinically acceptable. The high sensitivity, tunable laser source, low NEC and small fiber-optic ATR sensor demonstrate an encouraging step in the work towards precisely monitoring glucose levels in vivo. PMID:24466493

A Noninvasive Body Setup Method for Radiotherapy by Using a Multimodal Image Fusion Technique

PubMed Central

Zhang, Jie; Chen, Yunxia; Wang, Chenchen; Chu, Kaiyue; Jin, Jianhua; Huang, Xiaolin; Guan, Yue; Li, Weifeng

2017-01-01

Purpose: To minimize the mismatch error between patient surface and immobilization system for tumor location by a noninvasive patient setup method. Materials and Methods: The method, based on a point set registration, proposes a shift for patient positioning by integrating information of the computed tomography scans and that of optical surface landmarks. An evaluation of the method included 3 areas: (1) a validation on a phantom by estimating 100 known mismatch errors between patient surface and immobilization system. (2) Five patients with pelvic tumors were considered. The tumor location errors of the method were measured using the difference between the proposal shift of cone-beam computed tomography and that of our method. (3) The collected setup data from the evaluation of patients were compared with the published performance data of other 2 similar systems. Results: The phantom verification results showed that the method was capable of estimating mismatch error between patient surface and immobilization system in a precision of <0.22 mm. For the pelvic tumor, the method had an average tumor location error of 1.303, 2.602, and 1.684 mm in left–right, anterior–posterior, and superior–inferior directions, respectively. The performance comparison with other 2 similar systems suggested that the method had a better positioning accuracy for pelvic tumor location. Conclusion: By effectively decreasing an interfraction uncertainty source (mismatch error between patient surface and immobilization system) in radiotherapy, the method can improve patient positioning precision for pelvic tumor. PMID:29333959

Wavelength Dependence of Effective Pathlength Factor in Noninvasive Optical Measurements of Human Brain Functions

NASA Astrophysics Data System (ADS)

Sato, Hiroki; Kiguchi, Masashi; Maki, Atsushi

2006-04-01

In the noninvasive optical measurements of human brain functions, the dependence of pathlength factor in an activation area (effective pathlength factor: EPF) on wavelength was examined by simultaneously recording five wavelengths of 678, 692, 750, 782, and 830 nm, with three different source/detector distances of 20, 30, and 40 mm. We obtained an activation signal in the visual cortex using four wavelength pairs, where 830 nm was fixed as one wavelength. The dependence of EPF on the source/detector distance showed similar tendencies when the wavelengths of 692, 750, and 782 nm were considered. This suggests that it is feasible to use these wavelengths paired with an 830 nm wavelength to investigate the same region.

A novel method for fast imaging of brain function, non-invasively, with light

NASA Astrophysics Data System (ADS)

Chance, Britton; Anday, Endla; Nioka, Shoko; Zhou, Shuoming; Hong, Long; Worden, Katherine; Li, C.; Murray, T.; Ovetsky, Y.; Pidikiti, D.; Thomas, R.

1998-05-01

Imaging of the human body by any non-invasive technique has been an appropriate goal of physics and medicine, and great success has been obtained with both Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET) in brain imaging. Non-imaging responses to functional activation using near infrared spectroscopy of brain (fNIR) obtained in 1993 (Chance, et al. [1]) and in 1994 (Tamura, et al. [2]) are now complemented with images of pre-frontal and parietal stimulation in adults and pre-term neonates in this communication (see also [3]). Prior studies used continuous [4], pulsed [3] or modulated [5] light. The amplitude and phase cancellation of optical patterns as demonstrated for single source detector pairs affords remarkable sensitivity of small object detection in model systems [6]. The methods have now been elaborated with multiple source detector combinations (nine sources, four detectors). Using simple back projection algorithms it is now possible to image sensorimotor and cognitive activation of adult and pre- and full-term neonate human brain function in times < 30 sec and with two dimensional resolutions of < 1 cm in two dimensional displays. The method can be used in evaluation of adult and neonatal cerebral dysfunction in a simple, portable and affordable method that does not require immobilization, as contrasted to MRI and PET.

Label free measurement of retinal blood cell flux, velocity, hematocrit and capillary width in the living mouse eye

PubMed Central

Guevara-Torres, A.; Joseph, A.; Schallek, J. B.

2016-01-01

Measuring blood cell dynamics within the capillaries of the living eye provides crucial information regarding the health of the microvascular network. To date, the study of single blood cell movement in this network has been obscured by optical aberrations, hindered by weak optical contrast, and often required injection of exogenous fluorescent dyes to perform measurements. Here we present a new strategy to non-invasively image single blood cells in the living mouse eye without contrast agents. Eye aberrations were corrected with an adaptive optics camera coupled with a fast, 15 kHz scanned beam orthogonal to a capillary of interest. Blood cells were imaged as they flowed past a near infrared imaging beam to which the eye is relatively insensitive. Optical contrast of cells was optimized using differential scatter of blood cells in the split-detector imaging configuration. Combined, these strategies provide label-free, non-invasive imaging of blood cells in the retina as they travel in single file in capillaries, enabling determination of cell flux, morphology, class, velocity, and rheology at the single cell level. PMID:27867728

Label free measurement of retinal blood cell flux, velocity, hematocrit and capillary width in the living mouse eye.

PubMed

Guevara-Torres, A; Joseph, A; Schallek, J B

2016-10-01

Measuring blood cell dynamics within the capillaries of the living eye provides crucial information regarding the health of the microvascular network. To date, the study of single blood cell movement in this network has been obscured by optical aberrations, hindered by weak optical contrast, and often required injection of exogenous fluorescent dyes to perform measurements. Here we present a new strategy to non-invasively image single blood cells in the living mouse eye without contrast agents. Eye aberrations were corrected with an adaptive optics camera coupled with a fast, 15 kHz scanned beam orthogonal to a capillary of interest. Blood cells were imaged as they flowed past a near infrared imaging beam to which the eye is relatively insensitive. Optical contrast of cells was optimized using differential scatter of blood cells in the split-detector imaging configuration. Combined, these strategies provide label-free, non-invasive imaging of blood cells in the retina as they travel in single file in capillaries, enabling determination of cell flux, morphology, class, velocity, and rheology at the single cell level.

Quantum Dots for Molecular Diagnostics of Tumors

PubMed Central

Zdobnova, T.A.; Lebedenko, E.N.; Deyev, S.М.

2011-01-01

Semiconductor quantum dots (QDs) are a new class of fluorophores with unique physical and chemical properties, which allow to appreciably expand the possibilities for the current methods of fluorescent imaging and optical diagnostics. Here we discuss the prospects of QD application for molecular diagnostics of tumors ranging from cancer-specific marker detection on microplates to non-invasive tumor imagingin vivo. We also point out the essential problems that require resolution in order to clinically promote QD, and we indicate innovative approaches to oncology which are implementable using QD. PMID:22649672

Multifractal analysis of macro- and microcerebral circulation in rats

NASA Astrophysics Data System (ADS)

Pavlov, Alexey N.; Sindeeva, Olga S.; Sindeev, Sergey S.; Pavlova, Olga N.; Abdurashitov, Arkady S.; Rybalova, Elena V.; Semyachkina-Glushkovskaya, Oxana V.

2016-04-01

Application of noninvasive optical coherent-domain methods and advanced data processing tools such as the wavelet-based multifractal formalism allows revealing effective markers of early stages of functional distortions in the dynamics of cerebral vessels. Based on experiments performed in rats we discuss a possibility to diagnose a hidden stage of the development of intracranial hemorrhage (ICH). We also consider responses of the cerebrovascular dynamics to a pharmacologically induced increase in the peripheral blood pressure. We report distinctions occurring at the levels of macro- and microcerebral circulation.

Structural examination of easel paintings with optical coherence tomography.

PubMed

Targowski, Piotr; Iwanicka, Magdalena; Tymińska-Widmer, Ludmiła; Sylwestrzak, Marcin; Kwiatkowska, Ewa A

2010-06-15

Identification of the order, thickness, composition, and possibly the origin of the paint layers forming the structure of a painting, that is, its stratigraphy, is important in confirming its attribution and history as well as planning conservation treatments. The most common method of examination is analysis of a sample collected from the art object, both visually with a microscope and instrumentally through a variety of sophisticated, modern analytical tools. Because of its invasiveness, however, sampling is less than ideally compatible with conservation ethics; it is severely restricted with respect to the amount of material extirpated from the artwork. Sampling is also rather limited in that it provides only very local information. There is, therefore, a great need for a noninvasive method with sufficient in-depth resolution for resolving the stratigraphy of works of art. Optical coherence tomography (OCT) is a noninvasive, noncontact method of optical sectioning of partially transparent objects, with micrometer-level axial resolution. The method utilizes near-infrared light of low intensity (a few milliwatts) to obtain cross-sectional images of various objects; it has been mostly used in medical diagnostics. Through the serial collection of many such images, volume information may be extracted. The application of OCT to the examination of art objects has been in development since 2003. In this Account, we present a short introduction to the technique, briefly discuss the apparatus we use, and provide a paradigm for reading OCT tomograms. Unlike the majority of papers published previously, this Account focuses on one, very specific, use of OCT. We then consider two examples of successful, practical application of the technique. At the request of a conservation studio, the characteristics of inscriptions on two oil paintings, originating from the 18th and 19th centuries, were analyzed. In the first case, it was possible to resolve some questions concerning the history of the work. From an analysis of the positions of the paint layers involved in three inscriptions in relation to other strata of the painting, the order of events in its history was resolved. It was evident that the original text had been overpainted and that the other inscriptions were added later, thus providing convincing evidence as to the painting's true date of creation. In the second example, a painting was analyzed with the aim of confirming the possibility of forgery of the artist's signature, and evidence strongly supporting this supposition is presented. These two specific examples of successful use of the technique on paintings further demonstrate how OCT may be readily adaptable to other similar tasks, such as in the fields of forensic or materials science. In a synergistic approach, in which information is obtained with a variety of noninvasive techniques, OCT is demonstrably effective and offers great potential for further development.

Quantitative assessment of corneal viscoelasticity using optical coherence elastography and a modified Rayleigh-Lamb equation

NASA Astrophysics Data System (ADS)

Han, Zhaolong; Aglyamov, Salavat R.; Li, Jiasong; Singh, Manmohan; Wang, Shang; Vantipalli, Srilatha; Wu, Chen; Liu, Chih-hao; Twa, Michael D.; Larin, Kirill V.

2015-02-01

We demonstrate the use of a modified Rayleigh-Lamb frequency equation in conjunction with noncontact optical coherence elastography to quantify the viscoelastic properties of the cornea. Phase velocities of air-pulse-induced elastic waves were extracted by spectral analysis and used for calculating the Young's moduli of the samples using the Rayleigh-Lamb frequency equation (RLFE). Validation experiments were performed on 2% agar phantoms (n=3) and then applied to porcine corneas (n=3) in situ. The Young's moduli of the porcine corneas were estimated to be ˜60 kPa with a shear viscosity ˜0.33 Pa.s. The results demonstrate that the RLFE is a promising method for noninvasive quantification of the corneal biomechanical properties and may potentially be useful for clinical ophthalmological applications.

Visualization of retinal vascular structure and perfusion with a nonconfocal adaptive optics scanning light ophthalmoscope

PubMed Central

Sulai, Yusufu N.; Scoles, Drew; Harvey, Zachary; Dubra, Alfredo

2015-01-01

Imaging of the retinal vascular structure and perfusion was explored by confocal illumination and nonconfocal detection in an adaptive optics scanning light ophthalmoscope (AOSLO), as an extension of the work by Chui et al. [Biomed. Opt. Express 3, 2537 (2012)]. Five different detection schemes were evaluated at multiple retinal locations: circular mask, annular mask, circular mask with filament, knife-edge, and split-detector. Given the superior image contrast in the reflectance and perfusion maps, the split-detection method was further tested using pupil apodization, polarized detection, and four different wavelengths. None of these variations provided noticeable contrast improvement. The noninvasive visualization of capillary flow and structure provided by AOSLO split-detection shows great promise for studying ocular and systemic conditions that affect the retinal vasculature. PMID:24690655

A scalable correlator for multichannel diffuse correlation spectroscopy.

PubMed

Stapels, Christopher J; Kolodziejski, Noah J; McAdams, Daniel; Podolsky, Matthew J; Fernandez, Daniel E; Farkas, Dana; Christian, James F

2016-02-01

Diffuse correlation spectroscopy (DCS) is a technique which enables powerful and robust non-invasive optical studies of tissue micro-circulation and vascular blood flow. The technique amounts to autocorrelation analysis of coherent photons after their migration through moving scatterers and subsequent collection by single-mode optical fibers. A primary cost driver of DCS instruments are the commercial hardware-based correlators, limiting the proliferation of multi-channel instruments for validation of perfusion analysis as a clinical diagnostic metric. We present the development of a low-cost scalable correlator enabled by microchip-based time-tagging, and a software-based multi-tau data analysis method. We will discuss the capabilities of the instrument as well as the implementation and validation of 2- and 8-channel systems built for live animal and pre-clinical settings.

Optical monitoring of spinal cord subcellular damage after acute spinal cord injury

NASA Astrophysics Data System (ADS)

Shadgan, Babak; Manouchehri, Neda; So, Kitty; Shortt, Katelyn; Fong, Allan; Streijger, Femke; Macnab, Andrew; Kwon, Brian K.

2018-02-01

Introduction: Sudden physical trauma to the spinal cord results in acute spinal cord injury (SCI), leading to spinal cord (SC) tissue destruction, acute inflammation, increased SC intraparenchymal pressure, and tissue ischemia, hypoxia, and cellular necrosis. The ability to monitor SC tissue viability at subcellular level, using a real-time noninvasive method, would be extremely valuable to clinicians for estimating acute SCI damage, and adjusting and monitoring treatment in the intensive care setting. This study examined the feasibility and sensitivity of a custommade near infrared spectroscopy (NIRS) sensor to monitor the oxidation state of SC mitochondrial cytochrome aa3 (CCO), which reflects the subcellular damage of SC tissue in an animal model of SCI. Methods: Six anesthetized Yorkshire pigs were studied using a custom-made multi-wavelength NIRS system with a miniaturized optical sensor applied directly on the surgically exposed SC at T9. The oxidation states of SC tissue hemoglobin and CCO were monitored before, during and after acute SCI, and during mean arterial pressure alterations. Results: Non-invasive NIRS monitoring reflected changes in SC tissue CCO, simultaneous but independent of changes in hemoglobin saturation following acute SCI. A consistent decrease in SC tissue CCO chromophore concentration (-1.98 +/- 2.1 ab, p<0.05) was observed following SCI, indicating progressive SC cellular damage at the injury site. Elevation of mean arterial pressure can reduce SC tissue damage as suggested by different researchers and observed by significant increase in SC tissue CCO concentration (1.51 +/- 1.7 ab, p<0.05) in this study. Conclusions: This pilot study indicates that a novel miniaturized multi-wave NIRS sensor has the potential to monitor post-SCI changes of SC cytochrome aa3 oxygenation state in real time. Further development of this method may offer new options for improved SCI care.

In vivo stem cell tracking with imageable nanoparticles that bind bioorthogonal chemical receptors on the stem cell surface.

PubMed

Lee, Sangmin; Yoon, Hwa In; Na, Jin Hee; Jeon, Sangmin; Lim, Seungho; Koo, Heebeom; Han, Sang-Soo; Kang, Sun-Woong; Park, Soon-Jung; Moon, Sung-Hwan; Park, Jae Hyung; Cho, Yong Woo; Kim, Byung-Soo; Kim, Sang Kyoon; Lee, Taekwan; Kim, Dongkyu; Lee, Seulki; Pomper, Martin G; Kwon, Ick Chan; Kim, Kwangmeyung

2017-09-01

It is urgently necessary to develop reliable non-invasive stem cell imaging technology for tracking the in vivo fate of transplanted stem cells in living subjects. Herein, we developed a simple and well controlled stem cell imaging method through a combination of metabolic glycoengineering and bioorthogonal copper-free click chemistry. Firstly, the exogenous chemical receptors containing azide (-N 3 ) groups were generated on the surfaces of stem cells through metabolic glycoengineering using metabolic precursor, tetra-acetylated N-azidoacetyl-d-mannosamine(Ac 4 ManNAz). Next, bicyclo[6.1.0]nonyne-modified glycol chitosan nanoparticles (BCN-CNPs) were prepared as imageable nanoparticles to deliver different imaging agents. Cy5.5, iron oxide nanoparticles and gold nanoparticles were conjugated or encapsulated to BCN-CNPs for optical, MR and CT imaging, respectively. These imageable nanoparticles bound chemical receptors on the Ac 4 ManNAz-treated stem cell surface specifically via bioorthogonal copper-free click chemistry. Then they were rapidly taken up by the cell membrane turn-over mechanism resulting in higher endocytic capacity compared non-specific uptake of nanoparticles. During in vivo animal test, BCN-CNP-Cy5.5-labeled stem cells could be continuously tracked by non-invasive optical imaging over 15 days. Furthermore, BCN-CNP-IRON- and BCN-CNP-GOLD-labeled stem cells could be efficiently visualized using in vivo MR and CT imaging demonstrating utility of our stem cell labeling method using chemical receptors. These results conclude that our method based on metabolic glycoengineering and bioorthogonal copper-free click chemistry can stably label stem cells with diverse imageable nanoparticles representing great potential as new stem cell imaging technology. Copyright © 2017 Elsevier Ltd. All rights reserved.

High-definition optical coherence tomography and reflectance confocal microscopy in the in vivo visualization of a reaction to permanent make-up.

PubMed

Maier, T; Flaig, M J; Ruzicka, T; Berking, C; Pavicic, T

2015-03-01

After permanent make-up treatments, eczematous and granulomatous reactions may occur which need anti-inflammatory treatment. For the definite diagnosis oftentimes biopsies are recommended. In vivo imaging such as reflectance confocal microscopy (RCM) and high-definition optical coherence tomography (HD-OCT) has been successfully used in the non-invasive diagnosis of various dermatoses before. Here, we report on non-invasive imaging of a reaction towards permanent make-up in a 40-year-old woman by using HD-OCT and RCM. Both in HD-OCT and in RCM subepidermal pigment and granulomatous changes could be visualized and correlated with the histopathological findings. Regression of the lesions in response to topical steroids and intralesional injections of steroids and 5-fluorouracil is reported and treatment options are discussed. Non-invasive imaging techniques such as HD-OCT and RCM allow the visualization and localization of exogenous pigment and help in the evaluation of adverse reactions due to permanent make-up tattooing. © 2014 European Academy of Dermatology and Venereology.

Two-wavelength Raman detector for noninvasive measurements of carotenes and lycopene in human skin

NASA Astrophysics Data System (ADS)

Ermakov, Igor V.; Ermakova, Maia R.; Gellermann, Werner

2005-04-01

Carotenoids are an important part of the antioxidant system in human skin. Carotenoid molecules, provided by fruits and vegetables, are potent free radical quenchers that accumulate in the body. If not balanced by carotenoids and other antioxidants, free radicals may cause premature skin aging, oxidative cell damage, and even skin cancers. As carotenoids depletion may predispose a person to cancer or other disease, rapid and noninvasive measurement of carotenoid level in skin may be of preventive or diagnostic help. At the very least, such measurement can be used to obtain a biomarker for healthy levels of fruit and vegetable consumption. Recently we have developed noninvasive optical technique based on Raman spectroscopy. In this paper we describe compact optical detector for clinical applications that utilizes two-wavelength excitation. It selectively measures the two most prominent skin carotenoids found in the human skin, lycopene and carotenes. According to the medical literature, these two compounds may play different roles in the human body and be part of different tissue defense mechanisms. Dual-wavelength Raman measurements reveal significant differences in the carotenoid composition of different subjects.

Optoacoustic technique for noninvasive monitoring of blood oxygenation: a feasibility study

NASA Astrophysics Data System (ADS)

Esenaliev, Rinat O.; Larina, Irina V.; Larin, Kirill V.; Deyo, Donald J.; Motamedi, Massoud; Prough, Donald S.

2002-08-01

Replacement of invasive monitoring of cerebral venous oxygenation with noninvasive techniques offers great promise in the management of life-threatening neurologic illnesses including traumatic brain injury. We developed and built an optoacoustic system to noninvasively monitor cerebral venous oxygenation; the system includes a nanosecond Nd:YAG laser and a specially designed optoacoustic probe. We tested the system in vitro in sheep blood with experimentally varied oxygenation. Our results demonstrated that (1) the amplitude and temporal profile of the optoacoustic waves increase with blood oxygenation in the range from 24% to 92%, (2) optoacoustic signals can be detected despite optical and acoustic attenuation by thick bone, and (3) the system is capable of real-time and continuous measurements. These results suggest that the optoacoustic technique is technically feasible for continuous, noninvasive monitoring of cerebral venous oxygenation.

Failure analysis on optical fiber on swarm flight payload

NASA Astrophysics Data System (ADS)

Bourcier, Frédéric; Fratter, Isabelle; Teyssandier, Florent; Barenes, Magali; Dhenin, Jérémie; Peyriguer, Marie; Petre-Bordenave, Romain

2017-11-01

Failure analysis on optical components is usually carried-out, on standard testing devices such as optical/electronic microscopes and spectrometers, on isolated but representative samples. Such analyses are not contactless and not totally non-invasive, so they cannot be used easily on flight models. Furthermore, for late payload or satellite integration/validation phases with tight schedule issues, it could be necessary to carry out a failure analysis directly on the flight hardware, in cleanroom.

Microscanners for optical endomicroscopic applications

NASA Astrophysics Data System (ADS)

Hwang, Kyungmin; Seo, Yeong-Hyeon; Jeong, Ki-Hun

2017-12-01

MEMS laser scanning enables the miniaturization of endoscopic catheters for advanced endomicroscopy such as confocal microscopy, multiphoton microscopy, optical coherence tomography, and many other laser scanning microscopy. These advanced biomedical imaging modalities open a great potential for in vivo optical biopsy without surgical excision. They have huge capabilities for detecting on-demand early stage cancer with non-invasiveness. In this article, the scanning arrangement, trajectory, and actuation mechanism of endoscopic microscanners and their endomicroscopic applications will be overviewed.

Non-invasive structural and biomechanical imaging of the developing embryos (Conference Presentation)

NASA Astrophysics Data System (ADS)

Zhang, Jitao; Wu, Chen; Raghunathan, Raksha; Larin, Kirill V.; Scarcelli, Giuliano

2017-02-01

Embryos undergo dramatic changes in size, shape, and mechanical properties during development, which is regulated by both genetic and environmental factors. Quantifying mechanical properties of different embryonic tissues may represent good metrics for the embryonic health and proper development. Alternations and structure coupled with biomechanical information may provide a way for early diagnosis and drug treatment of various congenital diseases. Many methods have been developed to determine the mechanical properties of the embryo, such as atomic force microscopy (AFM), ultrasound elastography (UE), and optical coherent elastography (OCE). However, AFM is invasive and time-consuming. While UE and OCE are both non-invasive methods, the spatial resolutions are limited to mm to sub-mm, which is not enough to observe the details inside the embryo. Brillouin microscopy can potentially enable non-invasive measurement of the mechanical properties of a sample by measuring the spectra of acoustically induced light scattering therein. It has fast speed ( 0.1 second per point) and high resolution (sub-micron), and thus has been widely investigated for biomedical application, such as single cell and tissue. In this work, we utilized this technique to characterize the mechanical property of an embryo. A 2D elasticity imaging of the whole body of an E8 embryo was acquired by a Brillouin microscopy, and the stiffness changes between different organs (such as brain, heart, and spine) were shown. The elasticity maps were correlated with structural information provided by OCT.

Laser Doppler vibrometry: new ENT applications

NASA Astrophysics Data System (ADS)

Stasche, Norbert; Baermann, M.; Kempe, C.; Hoermann, Karl; Foth, Hans-Jochen

1996-12-01

Common audiometry often does not really allow a reliable and objective differential diagnosis of hearing disorders such as otosclerosis, adhesive otitis, ossicular interruption or tinnitus, even though several methods might be used complementarily. In recent years, some experimental studies on middle ear mechanics established laser Doppler vibrometry (LDV) as a useful method allowing objective measurement of human tympanic membrane displacement. The present study on LDV investigated the clinical use of this new method under physiological conditions. LDV proved to be a fast, reproducible, non-invasive and very sensitive instrument to characterize ear-drum vibrations in various middle ear dysfunctions, except in tinnitus patients. For future applications, improved optical characteristics of the vibrometer might result in a better differential diagnosis of subjective and objective tinnitus, otoacoustic emissions or Morbus Meniere.

In vivo glucose monitoring using dual-wavelength polarimetry to overcome corneal birefringence in the presence of motion.

PubMed

Pirnstill, Casey W; Malik, Bilal H; Gresham, Vincent C; Coté, Gerard L

2012-09-01

Over the past 35 years considerable research has been performed toward the investigation of noninvasive and minimally invasive glucose monitoring techniques. Optical polarimetry is one noninvasive technique that has shown promise as a means to ascertain blood glucose levels through measuring the glucose concentrations in the anterior chamber of the eye. However, one of the key limitations to the use of optical polarimetry as a means to noninvasively measure glucose levels is the presence of sample noise caused by motion-induced time-varying corneal birefringence. In this article our group presents, for the first time, results that show dual-wavelength polarimetry can be used to accurately detect glucose concentrations in the presence of motion-induced birefringence in vivo using New Zealand White rabbits. In total, nine animal studies (three New Zealand White rabbits across three separate days) were conducted. Using the dual-wavelength optical polarimetric approach, in vivo, an overall mean average relative difference of 4.49% (11.66 mg/dL) was achieved with 100% Zone A+B hits on a Clarke error grid, including 100% falling in Zone A. The results indicate that dual-wavelength polarimetry can effectively be used to significantly reduce the noise due to time-varying corneal birefringence in vivo, allowing the accurate measurement of glucose concentration in the aqueous humor of the eye and correlating that with blood glucose.

Long-term in vivo study of vertebrate embryonic development using noninvasive harmonics optical microscopy

NASA Astrophysics Data System (ADS)

Chen, Szu-Yu; Hsieh, C.-S.; Chu, S.-W.; Lin, Cheng-Yung; Ko, C.-Y.; Chen, Y.-C.; Tsai, Huai-Jen; Hu, C.-H.; Sun, Chi-Kuang

2005-03-01

Harmonics optical microscopy (HOM) provides a truly "noninvasive" tool for in vivo and long-term study of vertebrate embryonic development. Based on the nonlinear natures, it provides sub-micrometer 3D spatial resolution and high 3D optical-sectioning power (~1μm axial resolution) without using invasive and toxic fluorophores. Since only virtual-level-transition is involved, HOM is known to leave no energy deposition and no photodamages. Combined with second harmonic generation, which is sensitive to specific structure such as nerve and muscle fibers, HOM can be used to do functional studies of early developmental dynamics of many vertebrate physiological systems. Recently, zebrafish has become a standard model for many biological and medical studies of vertebrates, due to the similarity between embryonic development of zebrafish and human being. Zebrafish embryos now have been used to study many vertebrate physiological systems. We have demonstrated an in vivo HOM study of developmental dynamics of several embryonic physiological systems in live zebrafish embryos, with focuses on the developments of brains, eyes, ears, and hearts. Based on a femtosecond Cr:forsterite laser, which provides the deepest penetration (~1.5mm) and least photodamage in the zebrafish embryo, complete developing processes of different physiological systems within a period of time longer than 20 hours can be non-invasively observed inside the same embryo.

Real-time visualization of melanin granules in normal human skin using combined multiphoton and reflectance confocal microscopy.

PubMed

Majdzadeh, Ali; Lee, Anthony M D; Wang, Hequn; Lui, Harvey; McLean, David I; Crawford, Richard I; Zloty, David; Zeng, Haishan

2015-05-01

Recent advances in biomedical optics have enabled dermal and epidermal components to be visualized at subcellular resolution and assessed noninvasively. Multiphoton microscopy (MPM) and reflectance confocal microscopy (RCM) are noninvasive imaging modalities that have demonstrated promising results in imaging skin micromorphology, and which provide complementary information regarding skin components. This study assesses whether combined MPM/RCM can visualize intracellular and extracellular melanin granules in the epidermis and dermis of normal human skin. We perform MPM and RCM imaging of in vivo and ex vivo skin in the infrared domain. The inherent three-dimensional optical sectioning capability of MPM/RCM is used to image high-contrast granular features across skin depths ranging from 50 to 90 μm. The optical images thus obtained were correlated with conventional histologic examination including melanin-specific staining of ex vivo specimens. MPM revealed highly fluorescent granular structures below the dermal-epidermal junction (DEJ) region. Histochemical staining also demonstrated melanin-containing granules that correlate well in size and location with the granular fluorescent structures observed in MPM. Furthermore, the MPM fluorescence excitation wavelength and RCM reflectance of cell culture-derived melanin were equivalent to those of the granules. This study suggests that MPM can noninvasively visualize and quantify subepidermal melanin in situ. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Pulse Oximetry in the Physics Lab: A Colorful Alternative to Traditional Optics Curricula

ERIC Educational Resources Information Center

Kutschera, Ellynne; Dunlap, Justin C.; Byrd, Misti; Norlin, Casey; Widenhorn, Ralf

2013-01-01

We designed a physics laboratory exercise around pulse oximetry, a noninvasive medical technique used to assess a patient's blood oxygen saturation. An alternative to a traditional optics and light lab, this exercise teaches the principles of light absorption, spectroscopy, and the properties of light, while simultaneously studying a common…

The effects of water and lipids on NIR optical breast measurements

NASA Astrophysics Data System (ADS)

Cerussi, Albert E.; Bevilacqua, Frederic; Shah, Natasha; Jakubowski, Dorota B.; Berger, Andrew J.; Lanning, Ryan M.; Tromberg, Bruce J.

2001-06-01

Near infrared diffuse optical spectroscopy and imaging may enhance existing technologies for breast cancer screening, diagnosis, and treatment. NIR spectroscopy yields quantitative functional information that cannot be obtained with other non-invasive radiological techniques. In this study we focused upon the origins of this contrast in healthy breast, especially from water and lipids.

Optical Measurement Of Sound Pressure

NASA Technical Reports Server (NTRS)

Trinh, Eugene H.; Gaspar, Mark; Leung, Emily W.

1989-01-01

Noninvasive technique does not disturb field it measures. Sound field deflects laser beam proportionally to its amplitude. Knife edge intercepts undeflected beam, allowing only deflected beam to reach photodetector. Apparatus calibrated by comparing output of photodetector with that of microphone. Optical technique valuable where necessary to measure in remote, inaccessible, or hostile environment or to avoid perturbation of measured region.

Optimizing non-invasive radiofrequency hyperthermia treatment for improving drug delivery in 4T1 mouse breast cancer model

PubMed Central

Ware, Matthew J.; Krzykawska-Serda, Martyna; Chak-Shing Ho, Jason; Newton, Jared; Suki, Sarah; Law, Justin; Nguyen, Lam; Keshishian, Vazrik; Serda, Maciej; Taylor, Kimberly; Curley, Steven A.; Corr, Stuart J.

2017-01-01

Interactions of high-frequency radio waves (RF) with biological tissues are currently being investigated as a therapeutic platform for non-invasive cancer hyperthermia therapy. RF delivers thermal energy into tissues, which increases intra-tumoral drug perfusion and blood-flow. Herein, we describe an optical-based method to optimize the short-term treatment schedules of drug and hyperthermia administration in a 4T1 breast cancer model via RF, with the aim of maximizing drug localization and homogenous distribution within the tumor microenvironment. This method, based on the analysis of fluorescent dyes localized into the tumor, is more time, cost and resource efficient, when compared to current analytical methods for tumor-targeting drug analysis such as HPLC and LC-MS. Alexa-Albumin 647 nm fluorphore was chosen as a surrogate for nab-paclitaxel based on its similar molecular weight and albumin driven pharmacokinetics. We found that RF hyperthermia induced a 30–40% increase in Alexa-Albumin into the tumor micro-environment 24 h after treatment when compared to non-heat treated mice. Additionally, we showed that the RF method of delivering hyperthermia to tumors was more localized and uniform across the tumor mass when compared to other methods of heating. Lastly, we provided insight into some of the factors that influence the delivery of RF hyperthermia to tumors. PMID:28287120

Optimizing non-invasive radiofrequency hyperthermia treatment for improving drug delivery in 4T1 mouse breast cancer model.

PubMed

Ware, Matthew J; Krzykawska-Serda, Martyna; Chak-Shing Ho, Jason; Newton, Jared; Suki, Sarah; Law, Justin; Nguyen, Lam; Keshishian, Vazrik; Serda, Maciej; Taylor, Kimberly; Curley, Steven A; Corr, Stuart J

2017-03-13

Interactions of high-frequency radio waves (RF) with biological tissues are currently being investigated as a therapeutic platform for non-invasive cancer hyperthermia therapy. RF delivers thermal energy into tissues, which increases intra-tumoral drug perfusion and blood-flow. Herein, we describe an optical-based method to optimize the short-term treatment schedules of drug and hyperthermia administration in a 4T1 breast cancer model via RF, with the aim of maximizing drug localization and homogenous distribution within the tumor microenvironment. This method, based on the analysis of fluorescent dyes localized into the tumor, is more time, cost and resource efficient, when compared to current analytical methods for tumor-targeting drug analysis such as HPLC and LC-MS. Alexa-Albumin 647 nm fluorphore was chosen as a surrogate for nab-paclitaxel based on its similar molecular weight and albumin driven pharmacokinetics. We found that RF hyperthermia induced a 30-40% increase in Alexa-Albumin into the tumor micro-environment 24 h after treatment when compared to non-heat treated mice. Additionally, we showed that the RF method of delivering hyperthermia to tumors was more localized and uniform across the tumor mass when compared to other methods of heating. Lastly, we provided insight into some of the factors that influence the delivery of RF hyperthermia to tumors.

Optimizing non-invasive radiofrequency hyperthermia treatment for improving drug delivery in 4T1 mouse breast cancer model

NASA Astrophysics Data System (ADS)

Ware, Matthew J.; Krzykawska-Serda, Martyna; Chak-Shing Ho, Jason; Newton, Jared; Suki, Sarah; Law, Justin; Nguyen, Lam; Keshishian, Vazrik; Serda, Maciej; Taylor, Kimberly; Curley, Steven A.; Corr, Stuart J.

2017-03-01

Interactions of high-frequency radio waves (RF) with biological tissues are currently being investigated as a therapeutic platform for non-invasive cancer hyperthermia therapy. RF delivers thermal energy into tissues, which increases intra-tumoral drug perfusion and blood-flow. Herein, we describe an optical-based method to optimize the short-term treatment schedules of drug and hyperthermia administration in a 4T1 breast cancer model via RF, with the aim of maximizing drug localization and homogenous distribution within the tumor microenvironment. This method, based on the analysis of fluorescent dyes localized into the tumor, is more time, cost and resource efficient, when compared to current analytical methods for tumor-targeting drug analysis such as HPLC and LC-MS. Alexa-Albumin 647 nm fluorphore was chosen as a surrogate for nab-paclitaxel based on its similar molecular weight and albumin driven pharmacokinetics. We found that RF hyperthermia induced a 30-40% increase in Alexa-Albumin into the tumor micro-environment 24 h after treatment when compared to non-heat treated mice. Additionally, we showed that the RF method of delivering hyperthermia to tumors was more localized and uniform across the tumor mass when compared to other methods of heating. Lastly, we provided insight into some of the factors that influence the delivery of RF hyperthermia to tumors.

Celestial and terrestrial tele-ophthalmology: a health monitoring helmet for astronaut/cosmonaut and general public use

NASA Astrophysics Data System (ADS)

Ansari, Rafat R.; Rovati, Luigi; Sebag, Jerry

2001-06-01

A goggles-like head-mounted device equipped with several non-invasive techniques for quantitative medical evaluation of the eye, skin, and brain is envisioned for monitoring the health of astronauts and cosmonauts during long-term space travel and exploration. Real-time non-invasive evaluation of the different structures within these organs will provide indices of the health of these organs, as well as the entire body. The techniques such as dynamic light scattering (for the early detection of cataracts to evaluate effects of cosmic radiation), corneal autofluorescence (to assess extracellular matrix biology (e.g., diabetes), optical polarization (of aqueous fluid to evaluate serum chemistry), laser Doppler velocimetry (of retinal, optic nerve, and choroidal blood flow to assess ocular as well as central nervous system blood flow), reflectometry/oximetry (for oxygen metabolism), optical coherence tomography (for retinal microstructure), and possibility scanning laser technology for intraocular imaging and scanning will be integrated into this compact device.

Fluorescence laminar optical tomography for brain imaging: system implementation and performance evaluation.

PubMed

Azimipour, Mehdi; Sheikhzadeh, Mahya; Baumgartner, Ryan; Cullen, Patrick K; Helmstetter, Fred J; Chang, Woo-Jin; Pashaie, Ramin

2017-01-01

We present our effort in implementing a fluorescence laminar optical tomography scanner which is specifically designed for noninvasive three-dimensional imaging of fluorescence proteins in the brains of small rodents. A laser beam, after passing through a cylindrical lens, scans the brain tissue from the surface while the emission signal is captured by the epi-fluorescence optics and is recorded using an electron multiplication CCD sensor. Image reconstruction algorithms are developed based on Monte Carlo simulation to model light–tissue interaction and generate the sensitivity matrices. To solve the inverse problem, we used the iterative simultaneous algebraic reconstruction technique. The performance of the developed system was evaluated by imaging microfabricated silicon microchannels embedded inside a substrate with optical properties close to the brain as a tissue phantom and ultimately by scanning brain tissue in vivo. Details of the hardware design and reconstruction algorithms are discussed and several experimental results are presented. The developed system can specifically facilitate neuroscience experiments where fluorescence imaging and molecular genetic methods are used to study the dynamics of the brain circuitries.

Lung cell fiber evanescent wave spectroscopic biosensing of inhalation health hazards.

PubMed

Riley, Mark R; Lucas, Pierre; Le Coq, David; Juncker, Christophe; Boesewetter, Dianne E; Collier, Jayne L; DeRosa, Diana M; Katterman, Matthew E; Boussard-Plédel, Catherine; Bureau, Bruno

2006-11-05

Health risks associated with the inhalation of biological materials have been a topic of great concern; however, there are no rapid and automatable methods available to evaluate the potential health impact of inhaled materials. Here we describe a novel approach to evaluate the potential toxic effects of materials evaluated through cell-based spectroscopic analysis. Anchorage-dependent cells are grown on the surface of optical fibers transparent to infrared light. The probe system is composed of a single chalcogenide fiber (composed of Te, As, and Se) acting as both the sensor and transmission line for infrared optical signals. The cells are exposed to potential toxins and alterations of cellular composition are monitored through their impact on cellular spectral features. The signal is collected via evanescent wave absorption along the tapered sensing zone of the fiber through spectral changes between 3,000 and 600 cm(-1) (3,333-16,666 nm). Cell physiology, composition, and function are non-invasively tracked through monitoring infrared light absorption by the cell layer. This approach is demonstrated with an immortalized lung cell culture (A549, human lung carcinoma epithelia) in response to a variety of inhalation hazards including gliotoxin (a fungal metabolite), etoposide (a genotoxin), and methyl methansesulfonate (MMS, an alkylating agent). Gliotoxin impacts cell metabolism, etoposide impacts nucleic acids and the cell cycle, and MMS impacts nucleic acids and induces an immune response. This spectroscopic method is sensitive, non-invasive, and provides information on a wide range of cellular damage and response mechanisms and could prove useful for cell response screening of pharmaceuticals or for toxicological evaluations. (c) 2006 Wiley Periodicals, Inc.

Noninvasive imaging of absolute PpIX concentration distribution in nonmelanoma skin tumors at pre-PDT

NASA Astrophysics Data System (ADS)

Sunar, Ulas; Rohrbach, Daniel; Morgan, Janet; Zeitouni, Natalie

2013-03-01

Photodynamic Therapy (PDT) has proven to be an effective treatment option for nonmelanoma skin cancers. The ability to quantify the concentration of drug in the treated area is crucial for effective treatment planning as well as predicting outcomes. We utilized spatial frequency domain imaging for quantifying the accurate concentration of protoporphyrin IX (PpIX) in phantoms and in vivo. We correct fluorescence against the effects of native tissue absorption and scattering parameters. First we quantified the absorption and scattering of the tissue non-invasively. Then, we corrected raw fluorescence signal by compensating for optical properties to get the absolute drug concentration. After phantom experiments, we used basal cell carcinoma (BCC) model in Gli mice to determine optical properties and drug concentration in vivo at pre-PDT.

Noninvasive and Real-Time Plasmon Waveguide Resonance Thermometry

PubMed Central

Zhang, Pengfei; Liu, Le; He, Yonghong; Zhou, Yanfei; Ji, Yanhong; Ma, Hui

2015-01-01

In this paper, the noninvasive and real-time plasmon waveguide resonance (PWR) thermometry is reported theoretically and demonstrated experimentally. Owing to the enhanced evanescent field and thermal shield effect of its dielectric layer, a PWR thermometer permits accurate temperature sensing and has a wide dynamic range. A temperature measurement sensitivity of 9.4 × 10−3 °C is achieved and the thermo optic coefficient nonlinearity is measured in the experiment. The measurement of water cooling processes distributed in one dimension reveals that a PWR thermometer allows real-time temperature sensing and has potential to be applied for thermal gradient analysis. Apart from this, the PWR thermometer has the advantages of low cost and simple structure, since our transduction scheme can be constructed with conventional optical components and commercial coating techniques. PMID:25871718

Spectral-domain optical coherence tomography for endoscopic imaging

NASA Astrophysics Data System (ADS)

Chen, Xiaodong; Li, Qiao; Li, Wanhui; Wang, Yi; Yu, Daoyin

2007-02-01

Optical coherence tomography (OCT) is an emerging cross-sectional imaging technology. It uses broadband light sources to achieve axial image resolutions on the few micron scale. OCT is widely applied to medical imaging, it can get cross-sectional image of bio-tissue (transparent and turbid) with non-invasion and non-touch. In this paper, the principle of OCT is presented and the crucial parameters of the system are discussed in theory. With analysis of different methods and medical endoscopic system's feature, a design which combines the spectral domain OCT (SDOCT) technique and endoscopy is put forward. SDOCT provides direct access to the spectrum of the optical signal. It is shown to provide higher imaging speed when compared to time domain OCT. At the meantime, a novel OCT probe which uses advanced micromotor to drive reflecting prism is designed according to alimentary tract endoscopic feature. A simple optical coherence tomography system has been developed based on a fiber-based Michelson interferometer and spectrometer. An experiment which uses motor to drive prism to realize rotating imaging is done. Images obtained with this spectral interferometer are presented. The results verify the feasibility of endoscopic optical coherence tomography system with rotating scan.

Optical imaging of oral pathological tissue using optical coherence tomography and synchrotron radiation computed microtomography

NASA Astrophysics Data System (ADS)

Cânjǎu, Silvana; Todea, Carmen; Sinescu, Cosmin; Negrutiu, Meda L.; Duma, Virgil; Mǎnescu, Adrian; Topalǎ, Florin I.; Podoleanu, Adrian Gh.

2013-06-01

The efforts aimed at early diagnosis of oral cancer should be prioritized towards developing a new screening instrument, based on optical coherence tomography (OCT), to be used directly intraorally, able to perform a fast, real time, 3D and non-invasive diagnosis of oral malignancies. The first step in this direction would be to optimize the OCT image interpretation of oral tissues. Therefore we propose plastination as a tissue preparation method that better preserves three-dimensional structure for study by new optical imaging techniques. The OCT and the synchrotron radiation computed microtomography (micro-CT) were employed for tissue sample analyze. For validating the OCT results we used the gold standard diagnostic procedure for any suspicious lesion - histopathology. This is a preliminary study of comparing features provided by OCT and Micro-CT. In the conditions of the present study, OCT proves to be a highly promising imaging modality. The use of x-ray based topographic imaging of small biological samples has been limited by the low intrinsic x-ray absorption of non-mineralized tissue and the lack of established contrast agents. Plastination can be used to enhance optical imagies of oral soft tissue samples.

Remote skin tissue diagnostics in vivo by fiber optic evanescent wave Fourier transform infrared (FEW-FTIR) spectroscopy

NASA Astrophysics Data System (ADS)

Afanasyeva, Natalia I.; Kolyakov, Sergei F.; Butvina, Leonid N.

1998-04-01

The new method of fiber-optical evanescent wave Fourier transform IR (FEW-FTIR) spectroscopy has been applied to the diagnostics of normal tissue, as well as precancerous and cancerous conditions. The FEW-FTIR technique is nondestructive and sensitive to changes of vibrational spectra in the IR region, without heating and damaging human and animal skin tissue. Therefore this method and technique is an ideal diagnostic tool for tumor and cancer characterization at an early stage of development on a molecular level. The application of fiber optic technology in the middle IR region is relatively inexpensive and can be adapted easily to any commercially available tabletop FTIR spectrometers. This method of diagnostics is fast, remote, and can be applied to many fields Noninvasive medical diagnostics of skin cancer and other skin diseases in vivo, ex vivo, and in vitro allow for the development convenient, remote clinical applications in dermatology and related fields. The spectral variations from normal to pathological skin tissue and environmental influence on skin have been measured and assigned in the regions of 850-4000 cm-1. The lipid structure changes are discussed. We are able to develop the spectral histopathology as a fast and informative tool of analysis.

Research on optical properties of dental enamel for early caries diagnostics using a He-Ne laser

NASA Astrophysics Data System (ADS)

Tang, Jing; Liu, Li; Li, Song-zhan

2008-12-01

A new and non-invasive method adapted for optical diagnosis of early caries is proposed by researching on the interaction mechanism of laser with dental tissue and relations of remitted light with optical properties of the tissue. This method is based on simultaneous analyses of the following parameters: probing radiation, backscattering and auto-fluorescence. Investigation was performed on 104 dental samples in vitro by using He-Ne laser (λ=632.8nm, 2.0+/-0.1mW) as the probing. Spectrums of all samples were obtained. Characteristic spectrums of dental caries in various stages (intact, initial, moderate and deep) were given. Using the back-reflected light to normalize the intensity of back-scattering and fluorescence, a quantitative diagnosis standard for different stages of caries is proposed. In order to verify the test, comparison research was conducted among artificial caries, morphological damaged enamel, dental calculus and intact tooth. Results show that variations in backscattering characteristic changes in bio-tissue morphological and the quantity of auto-fluorescence is correlated with concentration of anaerobic microflora in hearth of caries lesion. This method poses a high potential of diagnosing various stages of dental caries, and is more reliability to detect early caries, surface damage of health enamel and dental calculus.

Glaucoma –state of the art and perspectives on treatment

PubMed Central

Wójcik-Gryciuk, Anna; Skup, Małgorzata; Waleszczyk, Wioletta J.

2015-01-01

Glaucoma is a chronic optic neuropathy characterized by progressive damage to the optic nerve, death of retinal ganglion cells and ultimately visual field loss. It is one of the leading causes of irreversible loss of vision worldwide. The most important trigger of glaucomatous damage is elevated eye pressure, and the current standard approach in glaucoma therapy is reduction of intraocular pressure (IOP). However, despite the use of effective medications or surgical treatment leading to lowering of IOP, progression of glaucomatous changes and loss of vision among patients with glaucoma is common. Therefore, it is critical to prevent vision loss through additional treatment. To implement such treatment(s), it is imperative to identify pathophysiological changes in glaucoma and develop therapeutic methods taking into account neuroprotection. Currently, there is no method of neuroprotection with long-term proven effectiveness in the treatment of glaucoma. Among the most promising molecules shown to protect the retina and optic nerve are neurotrophic factors. Thus, the current focus is on the development of safe and non-invasive methods for the long-term elevation of the intraocular level of neurotrophins through advanced gene therapy and topical eye treatment and on the search for selective agonists of neurotrophin receptors affording more efficient neuroprotection. PMID:26684267

Direct estimation of evoked hemoglobin changes by multimodality fusion imaging

PubMed Central

Huppert, Theodore J.; Diamond, Solomon G.; Boas, David A.

2009-01-01

In the last two decades, both diffuse optical tomography (DOT) and blood oxygen level dependent (BOLD)-based functional magnetic resonance imaging (fMRI) methods have been developed as noninvasive tools for imaging evoked cerebral hemodynamic changes in studies of brain activity. Although these two technologies measure functional contrast from similar physiological sources, i.e., changes in hemoglobin levels, these two modalities are based on distinct physical and biophysical principles leading to both limitations and strengths to each method. In this work, we describe a unified linear model to combine the complimentary spatial, temporal, and spectroscopic resolutions of concurrently measured optical tomography and fMRI signals. Using numerical simulations, we demonstrate that concurrent optical and BOLD measurements can be used to create cross-calibrated estimates of absolute micromolar deoxyhemoglobin changes. We apply this new analysis tool to experimental data acquired simultaneously with both DOT and BOLD imaging during a motor task, demonstrate the ability to more robustly estimate hemoglobin changes in comparison to DOT alone, and show how this approach can provide cross-calibrated estimates of hemoglobin changes. Using this multimodal method, we estimate the calibration of the 3 tesla BOLD signal to be −0.55% ± 0.40% signal change per micromolar change of deoxyhemoglobin. PMID:19021411

Three-dimensional imaging of artificial fingerprint by optical coherence tomography

NASA Astrophysics Data System (ADS)

Larin, Kirill V.; Cheng, Yezeng

2008-03-01

Fingerprint recognition is one of the popular used methods of biometrics. However, due to the surface topography limitation, fingerprint recognition scanners are easily been spoofed, e.g. using artificial fingerprint dummies. Thus, biometric fingerprint identification devices need to be more accurate and secure to deal with different fraudulent methods including dummy fingerprints. Previously, we demonstrated that Optical Coherence Tomography (OCT) images revealed the presence of the artificial fingerprints (made from different household materials, such as cement and liquid silicone rubber) at all times, while the artificial fingerprints easily spoofed the commercial fingerprint reader. Also we demonstrated that an analysis of the autocorrelation of the OCT images could be used in automatic recognition systems. Here, we exploited the three-dimensional (3D) imaging of the artificial fingerprint by OCT to generate vivid 3D image for both the artificial fingerprint layer and the real fingerprint layer beneath. With the reconstructed 3D image, it could not only point out whether there exists an artificial material, which is intended to spoof the scanner, above the real finger, but also could provide the hacker's fingerprint. The results of these studies suggested that Optical Coherence Tomography could be a powerful real-time noninvasive method for accurate identification of artificial fingerprints real fingerprints as well.

Screening spectroscopy of prostate cancer

NASA Astrophysics Data System (ADS)

Yermolenko, S. B.; Voloshynskyy, D. I.; Fedoruk, O. S.

2015-11-01

The aim of the study was to establish objective parameters of the field of laser and incoherent radiation of different spectral ranges (UV, visible, IR) as a non-invasive optical method of interaction with different samples of biological tissues and fluids of patients to determine the state of prostate cancer and choosing the best personal treatment. The objects of study were selected venous blood plasma of patient with prostate cancer, histological sections of rat prostate gland in the postoperative period. As diagnostic methods have been used ultraviolet spectrometry samples of blood plasma in the liquid state, infrared spectroscopy middle range (2,5-25 microns) dry residue of plasma by spectral diagnostic technique of thin histological sections of biological tissues.

Note: Non-invasive optical method for rapid determination of alignment degree of oriented nanofibrous layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pokorny, M.; Rebicek, J.; Klemes, J.

2015-10-15

This paper presents a rapid non-destructive method that provides information on the anisotropic internal structure of nanofibrous layers. A laser beam of a wavelength of 632.8 nm is directed at and passes through a nanofibrous layer prepared by electrostatic spinning. Information about the structural arrangement of nanofibers in the layer is directly visible in the form of a diffraction image formed on a projection screen or obtained from measured intensities of the laser beam passing through the sample which are determined by the dependency of the angle of the main direction of polarization of the laser beam on the axismore » of alignment of nanofibers in the sample. Both optical methods were verified on Polyvinyl alcohol (PVA) nanofibrous layers (fiber diameter of 470 nm) with random, single-axis aligned and crossed structures. The obtained results match the results of commonly used methods which apply the analysis of electron microscope images. The presented simple method not only allows samples to be analysed much more rapidly and without damaging them but it also makes possible the analysis of much larger areas, up to several square millimetres, at the same time.« less

Noncontact methods for measuring water-surface elevations and velocities in rivers: Implications for depth and discharge extraction

USGS Publications Warehouse

Nelson, Jonathan M.; Kinzel, Paul J.; McDonald, Richard R.; Schmeeckle, Mark

2016-01-01

Recently developed optical and videographic methods for measuring water-surface properties in a noninvasive manner hold great promise for extracting river hydraulic and bathymetric information. This paper describes such a technique, concentrating on the method of infrared videog- raphy for measuring surface velocities and both acoustic (laboratory-based) and laser-scanning (field-based) techniques for measuring water-surface elevations. In ideal laboratory situations with simple flows, appropriate spatial and temporal averaging results in accurate water-surface elevations and water-surface velocities. In test cases, this accuracy is sufficient to allow direct inversion of the governing equations of motion to produce estimates of depth and discharge. Unlike other optical techniques for determining local depth that rely on transmissivity of the water column (bathymetric lidar, multi/hyperspectral correlation), this method uses only water-surface information, so even deep and/or turbid flows can be investigated. However, significant errors arise in areas of nonhydrostatic spatial accelerations, such as those associated with flow over bedforms or other relatively steep obstacles. Using laboratory measurements for test cases, the cause of these errors is examined and both a simple semi-empirical method and computational results are presented that can potentially reduce bathymetric inversion errors.

Automated detection of the retinal from OCT spectral domain images of healthy eyes

NASA Astrophysics Data System (ADS)

Giovinco, Gaspare; Savastano, Maria Cristina; Ventre, Salvatore; Tamburrino, Antonello

2015-06-01

Optical coherence tomography (OCT) has become one of the most relevant diagnostic tools for retinal diseases. Besides being a non-invasive technique, one distinguished feature is its unique capability of providing (in vivo) cross-sectional view of the retinal. Specifically, OCT images show the retinal layers. From the clinical point of view, the identification of the retinal layers opens new perspectives to study the correlation between morphological and functional aspects of the retinal tissue. The main contribution of this paper is a new method/algorithm for the automated segmentation of cross-sectional images of the retina of healthy eyes, obtained by means of spectral domain optical coherence tomography (SD-OCT). Specifically, the proposed segmentation algorithm provides the automated detection of different retinal layers. Tests on experimental SD-OCT scans performed by three different instruments/manufacturers have been successfully carried out and compared to a manual segmentation made by an independent ophthalmologist, showing the generality and the effectiveness of the proposed method.

Automated detection of retinal layers from OCT spectral-domain images of healthy eyes

NASA Astrophysics Data System (ADS)

Giovinco, Gaspare; Savastano, Maria Cristina; Ventre, Salvatore; Tamburrino, Antonello

2015-12-01

Optical coherence tomography (OCT) has become one of the most relevant diagnostic tools for retinal diseases. Besides being a non-invasive technique, one distinguished feature is its unique capability of providing (in vivo) cross-sectional view of the retina. Specifically, OCT images show the retinal layers. From the clinical point of view, the identification of the retinal layers opens new perspectives to study the correlation between morphological and functional aspects of the retinal tissue. The main contribution of this paper is a new method/algorithm for the automated segmentation of cross-sectional images of the retina of healthy eyes, obtained by means of spectral-domain optical coherence tomography (SD-OCT). Specifically, the proposed segmentation algorithm provides the automated detection of different retinal layers. Tests on experimental SD-OCT scans performed by three different instruments/manufacturers have been successfully carried out and compared to a manual segmentation made by an independent ophthalmologist, showing the generality and the effectiveness of the proposed method.

Automated measurement of stent strut coverage in intravascular optical coherence tomography

NASA Astrophysics Data System (ADS)

Ahn, Chi Young; Kim, Byeong-Keuk; Hong, Myeong-Ki; Jang, Yangsoo; Heo, Jung; Joo, Chulmin; Seo, Jin Keun

2015-02-01

Optical coherence tomography (OCT) is a non-invasive, cross-sectional imaging modality that has become a prominent imaging method in percutaneous intracoronary intervention. We present an automated detection algorithm for stent strut coordinates and coverage in OCT images. The algorithm for stent strut detection is composed of a coordinate transformation from the polar to the Cartesian domains and application of second derivative operators in the radial and the circumferential directions. Local region-based active contouring was employed to detect lumen boundaries. We applied the method to the OCT pullback images acquired from human patients in vivo to quantitatively measure stent strut coverage. The validation studies against manual expert assessments demonstrated high Pearson's coefficients ( R = 0.99) in terms of the stent strut coordinates, with no significant bias. An averaged Hausdorff distance of < 120 μm was obtained for vessel border detection. Quantitative comparison in stent strut to vessel wall distance found a bias of < 12.3 μm and a 95% confidence of < 110 μm.

Photoacoustic measurement of epidermal melanin

NASA Astrophysics Data System (ADS)

Viator, John A.; Svaasand, Lars O.; Aguilar, Guillermo; Choi, Bernard; Nelson, J. Stuart

2003-06-01

Most dermatologic laser procedures must consider epidermal melanin, as it is a broadband optical absorber which affects subsurface fluence, effectively limiting the amount of light reaching the dermis and targeted chromophores. An accurate method for quantifying epidermal melanin content would aid clinicians in determining proper light dosage for therapeutic laser procedures. While epidermal melanin content has been quantified non-invasively using optical methods, there is currently no way to determine the melanin distribution in the epidermis. We have developed a photoacoustic probe that uses a Q-switched, frequency doubled Nd:YAG laser operating at 532nm to generate acoustic pulses in skin in vivo. The probe contained a piezoelectric element that detected photoacoustic waves which were then analyzed for epidermal melanin content, using a photoacoustic melanin index (PAMI). We tested 15 human subjects with skin types I--VI using the photoacoustic probe. We also present photoacoustic data for a human subject with vitiligo. Photoacoustic measurement showed melanin in the vitiligo subject was almost completely absent.

Visualization of Pulmonary Clearance Mechanisms via Noninvasive Optical Imaging Validated by Near-Infrared Flow Cytometry

PubMed Central

Zhou, Haiying; Gunsten, Sean P.; Zhegalova, Natalia G.; Bloch, Sharon; Achilefu, Samuel; Holley, J. Christopher; Schweppe, Daniel; Akers, Walter; Brody, Steven L.; Eades, William; Berezin, Mikhail Y.

2016-01-01

In vivo optical imaging with near-infrared (NIR) probes is an established method of diagnostics in preclinical and clinical studies. However, the specificities of these probes are difficult to validate ex vivo due to the lack of NIR flow cytometry. To address this limitation, we modified a flow cytometer to include an additional NIR channel using a 752 nm laser line. The flow cytometry system was tested using NIR microspheres and cell lines labeled with a combination of visible range and NIR fluorescent dyes. The approach was verified in vivo in mice evaluated for immune response in lungs after intratracheal delivery of the NIR contrast agent. Flow cytometry of cells obtained from the lung bronchoalveolar lavage demonstrated that the NIR dye was taken up by pulmonary macrophages as early as four-hours post-injection. This combination of optical imaging with NIR flow cytometry extends the capability of imaging and enables complementation of in vivo imaging with cell-specific studies. PMID:25808737

Two-layer optical model of skin for early, non-invasive detection of wound development on the diabetic foot

NASA Astrophysics Data System (ADS)

Yudovsky, Dmitry; Nouvong, Aksone; Schomacker, Kevin; Pilon, Laurent

2010-02-01

Foot ulceration is a debilitating comorbidity of diabetes that may result in loss of mobility and amputation. Optical detection of cutaneous tissue changes due to inflammation and necrosis at the preulcer site could constitute a preventative strategy. A commercial hyperspectral oximetry system was used to measure tissue oxygenation on the feet of diabetic patients. A previously developed predictive index was used to differentiate preulcer tissue from surrounding healthy tissue with a sensitivity of 92% and specificity of 80%. To improve prediction accuracy, an optical skin model was developed treating skin as a two-layer medium and explicitly accounting for (i) melanin content and thickness of the epidermis, (ii) blood content and hemoglobin saturation of the dermis, and (iii) tissue scattering in both layers. Using this forward model, an iterative inverse method was used to determine the skin properties from hyperspectral images of preulcerative areas. The use of this information in lowering the false positive rate was discussed.

Assessment of Sentinel Node Biopsies With Full-Field Optical Coherence Tomography.

PubMed

Grieve, Kate; Mouslim, Karima; Assayag, Osnath; Dalimier, Eugénie; Harms, Fabrice; Bruhat, Alexis; Boccara, Claude; Antoine, Martine

2016-04-01

Current techniques for the intraoperative analysis of sentinel lymph nodes during breast cancer surgery present drawbacks such as time and tissue consumption. Full-field optical coherence tomography is a novel noninvasive, high-resolution, fast imaging technique. This study investigated the use of full-field optical coherence tomography as an alternative technique for the intraoperative analysis of sentinel lymph nodes. Seventy-one axillary lymph nodes from 38 patients at Tenon Hospital were imaged minutes after excision with full-field optical coherence tomography in the pathology laboratory, before being handled for histological analysis. A pathologist performed a blind diagnosis (benign/malignant), based on the full-field optical coherence tomography images alone, which resulted in a sensitivity of 92% and a specificity of 83% (n = 65 samples). Regular feedback was given during the blind diagnosis, with thorough analysis of the images, such that features of normal and suspect nodes were identified in the images and compared with histology. A nonmedically trained imaging expert also performed a blind diagnosis aided by the reading criteria defined by the pathologist, which resulted in 85% sensitivity and 90% specificity (n = 71 samples). The number of false positives of the pathologist was reduced by 3 in a second blind reading a few months later. These results indicate that following adequate training, full-field optical coherence tomography can be an effective noninvasive diagnostic tool for extemporaneous sentinel node biopsy qualification. © The Author(s) 2015.

Swept-source optical coherence tomography of lower limb wound healing with histopathological correlation

NASA Astrophysics Data System (ADS)

Barui, Ananya; Banerjee, Provas; Patra, Rusha; Das, Raunak Kumar; Dhara, Santanu; Dutta, Pranab K.; Chatterjee, Jyotirmoy

2011-02-01

Direct noninvasive visualization of wound bed with depth information is important to understand the tissue repair. We correlate skin swept-source-optical coherence tomography (OCT) with histopathological and immunohistochemical evaluation on traumatic lower limb wounds under honey dressing to compare and assess the tissue repair features acquired noninvasively and invasively. Analysis of optical biopsy identifies an uppermost brighter band for stratum corneum with region specific thickness (p < 0.0001) and gray-level intensity (p < 0.0001) variation. Below the stratum corneum, variation in optical intensities is remarkable in different regions of the wound bed. Correlation between OCT and microscopic observations are explored especially in respect to progressive growth and maturation of the epithelial and subepithelial components. Characteristic transition of uniform hypolucid band in OCT image for depigmented zone to wavy highly lucid band in the pigmented zone could be directly correlated with the microscopic findings. The transformation of prematured epithelium of depigmented area, with low expression of E-cadherin, to matured epithelium with higher E-cadherin expression in pigmented zone, implicated plausible change in their optical properties as depicted in OCT. This correlated evaluation of multimodal images demonstrates applicability of swept-source-OCT in wound research and importance of integrated approach in validation of new technology.

Noninvasive measurement of internal jugular venous oxygen saturation by photoacoustic imaging

NASA Astrophysics Data System (ADS)

Garcia-Uribe, Alejandro; Erpelding, Todd N.; Ke, Haixin; Reddy, Kavya; Sharma, Anshuman; Wang, Lihong V.

2014-03-01

The metabolic rate and oxygen consumption of the brain is reflected in jugular venous oxygen saturation. In many clinical conditions, such as head trauma, stroke, and low cardiac output states, the brain is at risk for hypoxic-ischemic injury. The current gold standard for monitoring brain oxygenation is invasive and requires jugular vein catheterization under fluoroscopic guidance; and therefore it is rarely used. Photo-acoustic tomography in combination with ultrasound can be used to estimate oxygen saturation of the internal jugular vein in real-time. This noninvasive method will enable earlier detection and prevention of impending hypoxic brain injury. A wavelength-tunable dye laser pumped by a Nd:YAG laser delivers light through an optical fiber bundle, and a modified commercial ultrasound imaging system (Philips iU22) detects both the pulse-echo ultrasound (US) and photoacoustic (PA) signals. A custom-built multichannel data acquisition system renders co-registered ultrasound and photoacoustic images at 5 frames per second. After the jugular vein was localized in healthy volunteers, dualwavelength PA images were used to calculate the blood hemoglobin oxygen saturation from the internal jugular vein in vivo. The preliminary results raise confidence that this emerging technology can be used clinically as an accurate, noninvasive indicator of cerebral oxygenation.

Noninvasive monitoring of cerebral oxygenation in preterm infants: preliminary observations.

PubMed

Brazy, J E; Lewis, D V; Mitnick, M H; Jöbsis vander Vliet, F F

1985-02-01

A noninvasive optical method for bedside monitoring of cerebral oxygenation in small preterm infants was evaluated. Through differential absorbance of near infrared light, changes in the oxidation-reduction level of cytochrome aa3, in the oxygenation state of hemoglobin and in tissue blood volume were assessed in the transilluminated anterior cerebral field. Overall, cerebral oxygenated hemoglobin correlated significantly with transcutaneous oxygen, r = .44 p less than .0001; however, correlation was best in the absence of cardiorespiratory disease. Hypoxia with or without bradycardia led to hemoglobin deoxygenation and a shift in cytochrome aa3 to a more reduced state. When hypoxic episodes came in series or were prolonged, aa3 reduction occurred simultaneous with hemoglobin deoxygenation but its recovery to base-line values sometimes lagged behind the return of hemoglobin oxygenation. In one infant with a large patent ductus arteriosus, even brief episodes of mild bradycardia caused precipitous reduction of cytochrome aa3 before any shift to greater hemoglobin deoxygenation. This response disappeared after ductal ligation. In general, the antecedent state of cerebral oxygenation, the severity and duration of deoxygenation, and the presence or absence of circulatory abnormalities all influenced the aa3 response to hypoxia. Continuous noninvasive near infrared monitoring of cerebral oxygenation can be performed on sick preterm infants at the bedside.

Preventing Scars after Injury with Partial Irreversible Electroporation

PubMed Central

Golberg, Alexander; Villiger, Martin; Khan, Saiqa; Quinn, Kyle P.; Lo, William C. Y.; Bouma, Brett E.; Mihm, Martin C.; Austen, William G.; Yarmush, Martin L.

2017-01-01

Preventing the formation of hypertrophic scars, especially those that are a result of major trauma or burns, would have enormous impact in the fields of regenerative and trauma medicine. In this report, we introduce a non-invasive method to prevent scarring based on non-thermal partial irreversible electroporation. Contact burn injuries in rats were treated with varying treatment parameters to optimize the treatment protocol. Scar surface area and structural properties of the scar were assessed with histology and non-invasive, longitudinal imaging with polarization-sensitive optical coherence tomography. We found that partial irreversible electroporation using 200 pulses of 250 V and 70 μs duration, delivered at 3 Hz every 20 days during a total of five therapy sessions after the initial burn injury resulted in a 57.9% reduction of the scar area in comparison with untreated scars and structural features approaching those of normal skin. Noteworthy, unlike humans, rats do not develop hypertrophic scars. Therefore, the use of a rat animal model is the limiting factor of this work. PMID:27393126

Noninvasive optical monitoring multiple physiological parameters response to cytokine storm

NASA Astrophysics Data System (ADS)

Li, Zebin; Li, Ting

2018-02-01

Cancer and other disease originated by immune or genetic problems have become a main cause of death. Gene/cell therapy is a highlighted potential method for the treatment of these diseases. However, during the treatment, it always causes cytokine storm, which probably trigger acute respiratory distress syndrome and multiple organ failure. Here we developed a point-of-care device for noninvasive monitoring cytokine storm induced multiple physiological parameters simultaneously. Oxy-hemoglobin, deoxy-hemoglobin, water concentration and deep-tissue/tumor temperature variations were simultaneously measured by extended near infrared spectroscopy. Detection algorithms of symptoms such as shock, edema, deep-tissue fever and tissue fibrosis were developed and included. Based on these measurements, modeling of patient tolerance and cytokine storm intensity were carried out. This custom device was tested on patients experiencing cytokine storm in intensive care unit. The preliminary data indicated the potential of our device in popular and milestone gene/cell therapy, especially, chimeric antigen receptor T-cell immunotherapy (CAR-T).

Non-invasive technique to measure biogeochemical parameters (pH and O2) in a microenvironment: Design and applications

NASA Astrophysics Data System (ADS)

Li, Biting; Seliman, Ayman; Pales, Ashley; Liang, Weizhen; Sams, Allison; Darnault, Christophe; Devol, Timothy

2017-04-01

The primary objectives of this research are to do the pH and O2 sensor foils calibration and then to test them in applications. Potentially, this project can be utilized to monitor the fate and transport of radionuclides in porous media. The information for physical and chemical parameters (e.g. pH and O2) is crucial to know when determining contaminants' behavior and transport in the environment. As a non-invasive method, optical imaging technique using a DSLR camera could capture data on the foil when it fluoresces, and gives a high temporal and spatial resolution during the experimental period. The calibration procedures were done in cuvettes in a row. The preliminary experiments could measure pH value in the range from 4.5 to 7.5, and O2 concentration from 0 mg/L to 20.74 mg/L. Applications of sensor foils have involved nano zero valent and acid rain experiments in order to obtain a gradient of parameter changes.

Non-invasive in-vivo Raman spectroscopic measurement of the dynamics of the antioxidant substance lycopene in the human skin after a dietary supplementation

NASA Astrophysics Data System (ADS)

Darvin, M. E.; Gersonde, I.; Albrecht, H.; Sterry, W.; Lademann, J.

2007-05-01

A non-invasive optical method based on resonance Raman spectroscopy was used for the in vivo detection of the concentration of the carotenoid antioxidant substance lycopene in the human skin. The physiological variation of the level of lycopene in the skin during a 6 month period was measured daily in 7 volunteers. It was shown that all volunteers had a different individual level of lycopene in the skin, depending on the lifestyle of volunteers. It was shown that the supplementation of the foodstuffs containing lycopene, such as tomato products and some fruits, increases the level of lycopene in the skin. The increase in the lycopene level can be usually observed on the next day after the supplementation. The present results demonstrate that a diet rich in products containing a high amount of carotenoids, such as lycopene, can be an efficient strategy to increase the carotenoid level of the skin.

[The design and application of domestic mid-IR fiber optics].

PubMed

Weng, Shi-fu; Gao, Jian-ping; Xu, Yi-zhuang; Yang, Li-min; Bian, Bei-ya; Xiang, Hai-bo; Wu, Jin-guang

2004-05-01

The combination of mid-IR fiber optics and FTIR has made the non-invasive determination of samples in situ, with long distances, and in vivo possible. In this paper domestic mid-IR fiber optics was improved to investigate the transmission ability of fiber optics and its application to the sample determination. New design was applied to obtaining one bare fiber optics, which has a minor energy loss and higher signal-to-noise ratio. The spectra of H2O/EtOH and tissue samples were measured using the new designed fiber optics and the results show that home-made mid-IR fiber optics can be applied to the field of determination of general and biological samples.

Longitudinal evaluation of patients with oral potentially malignant disorders using optical imaging and spectroscopy

NASA Astrophysics Data System (ADS)

Schwarz, Richard A.; Pierce, Mark C.; Mondrik, Sharon; Gao, Wen; Quinn, Mary K.; Bhattar, Vijayashree; Williams, Michelle D.; Vigneswaran, Nadarajah; Gillenwater, Ann M.; Richards-Kortum, Rebecca

2012-02-01

Dysplastic and cancerous alterations in oral tissue can be detected noninvasively in vivo using optical techniques including autofluorescence imaging, high-resolution imaging, and spectroscopy. Interim results are presented from a longitudinal study in which optical imaging and spectroscopy were used to evaluate the progression of lesions over time in patients at high risk for development of oral cancer. Over 100 patients with oral potentially malignant disorders have been enrolled in the study to date. Areas of concern in the oral cavity are measured using widefield autofluorescence imaging and depth-sensitive optical spectroscopy during successive clinical visits. Autofluorescence intensity patterns and autofluorescence spectra are tracked over time and correlated with clinical observations. Patients whose lesions progress and who undergo surgery are also measured in the operating room immediately prior to surgery using autofluorescence imaging and spectroscopy, with the addition of intraoperative high-resolution imaging to characterize nuclear size, nuclear crowding, and tissue architecture at selected sites. Optical measurements are compared to histopathology results from biopsies and surgical specimens collected from the measured sites. Autofluorescence imaging and spectroscopy measurements are continued during post-surgery followup visits. We examined correlations between clinical impression and optical classification over time with an average followup period of 4 months. The data collected to date suggest that multimodal optical techniques may aid in noninvasive monitoring of the progression of oral premalignant lesions, biopsy site selection, and accurate delineation of lesion extent during surgery.

Noninvasive label-free monitoring of cosmetics and pharmaceuticals in human skin using nonlinear optical microscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Osseiran, Sam; Wang, Hequn; Evans, Conor L.

2017-02-01

Over the past decade, nonlinear optical microscopy has seen a dramatic rise in its use in research settings due to its noninvasiveness, enhanced penetration depth, intrinsic optical sectioning, and the ability to probe chemical compounds with molecular specificity without exogenous contrast agents. Nonlinear optical techniques including two-photon excitation fluorescence (2PEF), fluorescence lifetime imaging microscopy (FLIM), second harmonic generation (SHG), coherent anti-Stokes and stimulated Raman scattering (CARS and SRS, respectively), as well as transient and sum frequency absorption (TA and SFA, respectively), have been widely used to explore the physiology and microanatomy of skin. Recently, these modalities have shed light on dermal processes that could not have otherwise been observed, including the spatiotemporal monitoring of cosmetics and pharmaceuticals. However, a challenge quickly arises when studying such chemicals in a dermatological context: many exogenous compounds have optical signatures that can interfere with the signals that would otherwise be acquired from intact skin. For example, oily solvents exhibit strong signals when probing CH2 vibrations with CARS/SRS; chemical sun filters appear bright in 2PEF microscopy; and darkly colored compounds readily absorb light across a broad spectrum, producing strong TA/SFA signals. Thus, this discussion will first focus on the molecular contrast in skin that can be probed using the aforementioned nonlinear optical techniques. This will be followed by an overview of strategies that take advantage of the exogenous compounds' optical signatures to probe spatiotemporal dynamics while preserving endogenous information from skin.

Non-invasive prediction of forthcoming cirrhosis-related complications

PubMed Central

Kang, Wonseok; Kim, Seung Up; Ahn, Sang Hoon

2014-01-01

In patients with chronic liver diseases, identification of significant liver fibrosis and cirrhosis is essential for determining treatment strategies, assessing therapeutic response, and stratifying long-term prognosis. Although liver biopsy remains the reference standard for evaluating the extent of liver fibrosis in patients with chronic liver diseases, several non-invasive methods have been developed as alternatives to liver biopsies. Some of these non-invasive methods have demonstrated clinical accuracy for diagnosing significant fibrosis or cirrhosis in many cross-sectional studies with the histological fibrosis stage as a reference standard. However, non-invasive methods cannot be fully validated through cross-sectional studies since liver biopsy is not a perfect surrogate endpoint marker. Accordingly, recent studies have focused on assessing the performance of non-invasive methods through long-term, longitudinal, follow-up studies with solid clinical endpoints related to advanced stages of liver fibrosis and cirrhosis. As a result, current view is that these alternative methods can independently predict future cirrhosis-related complications, such as hepatic decompensation, liver failure, hepatocellular carcinoma, or liver-related death. The clinical role of non-invasive models seems to be shifting from a simple tool for predicting the extent of fibrosis to a surveillance tool for predicting future liver-related events. In this article, we will summarize recent longitudinal studies of non-invasive methods for predicting forthcoming complications related to liver cirrhosis and discuss the clinical value of currently available non-invasive methods based on evidence from the literature. PMID:24627597

A multiple reflection model for the investigation of infrared transmission of a graphene/substrate system

NASA Astrophysics Data System (ADS)

Zhang, Jie; Ding, Lan; Liang, Changneng; Xiao, Yiming; Xu, Wen

2017-11-01

We develop a multiple reflection model (MRM) for the examination of infrared transmission properties of a graphene/substrate system. The incident angle and the multiple reflection beams in the substrate with finite thickness are taken into consideration. The model can be applied to predict the optical responses of graphene/substrate systems or to extract the real part of the optical conductance of graphene from the experimental measurement. As an example, we calculate the relative transmittance of graphene/quartz and graphene/sapphire systems by using MRM and provide an experimental verification in the near-infrared range. The measured results show good agreement with the calculated ones. Our method can be easily extended to accurately and non-invasively identify the layer numbers of other 2D materials, and assess the quality of them.

A micromechanical device that monitors arterial pressure during general anesthesia and in intensive care units

NASA Astrophysics Data System (ADS)

Andreeva, A. V.; Luchinin, V. V.; Kuzmina, K. A.; Klyavinek, A. S.; Karelov, A. E.

2015-12-01

A vibroacoustic fiber optic system that consists of micromechanical components designated for use in medicine and biology is reviewed. A theoretical analysis of a fiber optic microphone is done and its optimal construction parameters are determined. The possibility of using the developed system with magnetic resonance tomography to noninvasively measure man's arterial pressure is specified.

Skin collagen can be accurately quantified through noninvasive optical method: Validation on a swine study.

PubMed

Tzeng, S-Y; Kuo, T-Y; Hu, S-B; Chen, Y-W; Lin, Y-L; Chu, K-Y; Tseng, S-H

2018-02-01

Diffuse reflectance spectroscopy (DRS) is a noninvasive optical technology characterized by relatively low system cost and high efficiency. In our previous study, we quantified the relative concentration of collagen for the individual keloid patient. However, no actual value of collagen concentration can prove the reliability of collagen detection by our DRS system. Skin-mimicking phantoms were prepared using different collagen and coffee concentrations, and their chromophore concentrations were quantified using the DRS system to analyze the influence of collagen and other chromophores. Moreover, we used the animal study to compare the DRS system with the collagen evaluation of biopsy section by second-harmonic generation (SHG) microscopy at four different skin parts. In the phantom study, the result showed that coffee chromophore did not severely interfere with collagen concentration recovery. In the animal study, a positive correlation (r=.902) between the DRS system and collagen evaluation with SHG microscopy was found. We have demonstrated that the DRS system can quantify the actual values of collagen concentration and excluded the interference of other chromophores in skin-mimicking phantoms. Furthermore, a high positive correlation was found in the animal study with SHG microscopy. We consider that the DRS is a potential technique and can evaluate skin condition objectively. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Fiber-based hybrid probe for non-invasive cerebral monitoring in neonatology

NASA Astrophysics Data System (ADS)

Rehberger, Matthias; Giovannella, Martina; Pagliazzi, Marco; Weigel, Udo; Durduran, Turgut; Contini, Davide; Spinelli, Lorenzo; Pifferi, Antonio; Torricelli, Alessandro; Schmitt, Robert

2015-07-01

Improved cerebral monitoring systems are needed to prevent preterm infants from long-term cognitive and motor restrictions. Combining advanced near-infrared diffuse spectroscopy measurement technologies, time-resolved spectroscopy (TRS) and diffuse correlation spectroscopy (DCS) will introduce novel indicators of cerebral oxygen metabolism and blood flow for neonatology. For non-invasive sensing a fiber-optical probe is used to send and receive light from the infant head. In this study we introduce a new fiber-based hybrid probe that is designed for volume production. The probe supports TRS and DCS measurements in a cross geometry, thus both technologies gain information on the same region inside the tissue. The probe is highly miniaturized to perform cerebral measurements on heads of extreme preterm infants down to head diameters of 6cm. Considerations concerning probe production focus on a reproducible accuracy in shape and precise optical alignment. In this way deviations in measurement data within a series of probes should be minimized. In addition to that, requirements for clinical use like robustness and hygiene are considered. An additional soft-touching sleeve made of FDA compatible silicone allows for a flexible attachment with respect to the individual anatomy of each patient. We present the technical concept of the hybrid probe and corresponding manufacturing methods. A prototype of the probe is shown and tested on tissue phantoms as well as in vivo to verify its operational reliability.

Noninvasively Imaging Subcutaneous Tumor Xenograft by a Handheld Raman Detector, with the Assistance of an Optical Clearing Agent.

PubMed

Zhang, Yunfei; Liu, Haoran; Tang, Jiali; Li, Zhuoyun; Zhou, Xingyu; Zhang, Ren; Chen, Liang; Mao, Ying; Li, Cong

2017-05-31

A handheld Raman detector with operational convenience, high portability, and rapid acquisition rate has been applied in clinics for diagnostic purposes. However, the inherent weakness of Raman scattering and strong scattering of the turbid tissue restricts its utilization to superficial locations. To extend the applications of a handheld Raman detector to deep tissues, a gold nanostar-based surface-enhanced Raman scattering (SERS) nanoprobe with robust colloidal stability, a fingerprint-like spectrum, and extremely high sensitivity (5.0 fM) was developed. With the assistance of FPT, a multicomponent optical clearing agent (OCA) efficiently suppressing light scattering from the turbid dermal tissues, the handheld Raman detector noninvasively visualized the subcutaneous tumor xenograft with a high target-to-background ratio after intravenous injection of the gold nanostar-based SERS nanoprobe. To the best of our knowledge, this work is the first example to introduce the optical clearing technique in assisting SERS imaging in vivo. The combination of optical clearing technology and SERS is a promising strategy for the extension of the clinical applications of the handheld Raman detector from superficial tissues to subcutaneous or even deeper lesions that are usually "concealed" by the turbid dermal tissue.

Near-Infrared Neuroimaging with NinPy

PubMed Central

Strangman, Gary E.; Zhang, Quan; Zeffiro, Thomas

2009-01-01

There has been substantial recent growth in the use of non-invasive optical brain imaging in studies of human brain function in health and disease. Near-infrared neuroimaging (NIN) is one of the most promising of these techniques and, although NIN hardware continues to evolve at a rapid pace, software tools supporting optical data acquisition, image processing, statistical modeling, and visualization remain less refined. Python, a modular and computationally efficient development language, can support functional neuroimaging studies of diverse design and implementation. In particular, Python's easily readable syntax and modular architecture allow swift prototyping followed by efficient transition to stable production systems. As an introduction to our ongoing efforts to develop Python software tools for structural and functional neuroimaging, we discuss: (i) the role of non-invasive diffuse optical imaging in measuring brain function, (ii) the key computational requirements to support NIN experiments, (iii) our collection of software tools to support NIN, called NinPy, and (iv) future extensions of these tools that will allow integration of optical with other structural and functional neuroimaging data sources. Source code for the software discussed here will be made available at www.nmr.mgh.harvard.edu/Neural_SystemsGroup/software.html. PMID:19543449

Assessment of microcirculation dynamics during cutaneous wound healing phases in vivo using optical microangiography

PubMed Central

Yousefi, Siavash; Qin, Jia; Dziennis, Suzan; Wang, Ruikang K.

2014-01-01

Abstract. Cutaneous wound healing consists of multiple overlapping phases starting with blood coagulation following incision of blood vessels. We utilized label-free optical coherence tomography and optical microangiography (OMAG) to noninvasively monitor healing process and dynamics of microcirculation system in a mouse ear pinna wound model. Mouse ear pinna is composed of two layers of skin separated by a layer of cartilage and because its total thickness is around 500 μm, it can be utilized as an ideal model for optical imaging techniques. These skin layers are identical to human skin structure except for sweat ducts and glands. Microcirculatory system responds to the wound injury by recruiting collateral vessels to supply blood flow to hypoxic region. During the inflammatory phase, lymphatic vessels play an important role in the immune response of the tissue and clearing waste from interstitial fluid. In the final phase of wound healing, tissue maturation, and remodeling, the wound area is fully closed while blood vessels mature to support the tissue cells. We show that using OMAG technology allows noninvasive and label-free monitoring and imaging each phase of wound healing that can be used to replace invasive tissue sample histology and immunochemistry technologies. PMID:25036212

In vivo imaging of endogenous enzyme activities using luminescent 1,2-dioxetane compounds.

PubMed

Tseng, Jen-Chieh; Kung, Andrew L

2015-06-24

Here we present a non-invasive imaging method for visualizing endogenous enzyme activities in living animals. This optical imaging method is based on an energy transfer principle termed chemically initiated electron exchange luminescence (CIEEL). The light energy is provided by enzymatic activation of metastable 1,2-dioxetane substrates, whose protective groups are removed by hydrolytic enzymes such as β-galactosidase and alkaline phosphatase. In the presence of a nearby fluorescent recipient, the chemical energy within the activated substrate is then transferred via formation of a charge-transfer complex with the fluorophore, a mechanism closely related to glow stick chemistry. Efficient CIEEL energy transfer requires close proximity between the trigger enzyme and the fluorescent recipient. Using cells stained with fluorescent dialkylcarbocyanines as the energy recipients, we demonstrated CIEEL imaging of cellular β-galactosidase or alkaline phosphatase activity. In living animals, we used a similar approach to non-invasively image alkaline phosphatase activity in the peritoneal cavity. In this report, we provide proof-of-concept for CIEEL imaging of in vivo enzymatic activity. In addition, we demonstrate the use of CIEEL energy transfer for visualizing elevated alkaline phosphatase activity associated with tissue inflammation in living animals.

Application and Miniaturization of Linear and Nonlinear Raman Microscopy for Biomedical Imaging

NASA Astrophysics Data System (ADS)

Mittal, Richa

Current diagnostics for several disorders rely on surgical biopsy or evaluation of ex vivo bodily fluids, which have numerous drawbacks. We evaluated the potential for vibrational techniques (both linear and nonlinear Raman) as a reliable and noninvasive diagnostic tool. Raman spectroscopy is an optical technique for molecular analysis that has been used extensively in various biomedical applications. Based on demonstrated capabilities of Raman spectroscopy we evaluated the potential of the technique for providing a noninvasive diagnosis of mucopolysaccharidosis (MPS). These studies show that Raman spectroscopy can detect subtle changes in tissue biochemistry. In applications where sub-micrometer visualization of tissue compositional change is required, a transition from spectroscopy to high quality imaging is necessary. Nonlinear vibrational microscopy is sensitive to the same molecular vibrations as linear Raman, but features fast imaging capabilities. Coherent Raman scattering when combined with other nonlinear optical (NLO) techniques (like two-photon excited fluorescence and second harmonic generation) forms a collection of advanced optical techniques that provide noninvasive chemical contrast at submicron resolution. This capability to examine tissues without external molecular agents is driving the NLO approach towards clinical applications. However, the unique imaging capabilities of NLO microscopy are accompanied by complex instrument requirements. Clinical examination requires portable imaging systems for rapid inspection of tissues. Optical components utilized in NLO microscopy would then need substantial miniaturization and optimization to enable in vivo use. The challenges in designing compact microscope objective lenses and laser beam scanning mechanisms are discussed. The development of multimodal NLO probes for imaging oral cavity tissue is presented. Our prototype has been examined for ex vivo tissue imaging based on intrinsic fluorescence and SHG contrast. These studies show a potential for multiphoton compact probes to be used for real time imaging in the clinic.

Optical biopsy for the diagnosis of dysplasia in Barrett's oesophagus

NASA Astrophysics Data System (ADS)

Pickard, David C. O.; Bigio, Irving J.; Bown, Stephen G.; Lovat, Laurence B.; Ripley, Paul M.; Novelli, Marco

2002-05-01

Several research groups have been developing optical-spectroscopy methods, often mediated by fibre-optic probes, to noninvasively identify dysplasia and cancer in situ and in real time: often called 'optical biopsy'. Researchers at Los Alamos National Laboratory (Los Alamos, New Mexico) have developed the method of elastic-scattering spectroscopy (ESS). ESS is a point measurement that is sensitive to the morphological changes at the cellular and sub-cellular level, including changes in the size and/or density of the nuclei, mitochondria or other organelles. It is therefore sensitive to morphology features that a pathologist looks for during histological examination. We report on the first stages of a clinical study currently under way at the Middlesex Hospital an University College London, designed to test the ESS method for identification of dysplasia in Barrett's oesophagus. Preliminary results using elastic-scattering spectroscopy during endoscopic examination show that this technique has potential as a real-time test for in vivo detection of dysplasia or early cancer within Barrett's mucosa, or at least as a guide to assist in locating optimum sites for biopsy. Initial data sets are encouraging and the randomly chosen testing and training sets give specificities and sensitivities comparable to the accuracy of histology. It is evident that the ESS technique is proving to be convenient for the physicians given its speed and compatibility with endoscopic equipment. It is intended to begin prospective trials in the next few months to assess the systems suitability for general clinical practice.

Reconstructing in-vivo reflectance spectrum of pigmented skin lesion by Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Wang, Shuang; He, Qingli; Zhao, Jianhua; Lui, Harvey; Zeng, Haishan

2012-03-01

In dermatology applications, diffuse reflectance spectroscopy has been extensively investigated as a promising tool for the noninvasive method to distinguish melanoma from benign pigmented skin lesion (nevus), which is concentrated with the skin chromophores like melanin and hemoglobin. We carried out a theoretical study to examine melanin distribution in human skin tissue and establish a practical optical model for further pigmented skin investigation. The theoretical simulation was using junctional nevus as an example. A multiple layer skin optical model was developed on established anatomy structures of skin, the published optical parameters of different skin layers, blood and melanin. Monte Carlo simulation was used to model the interaction between excitation light and skin tissue and rebuild the diffuse reflectance process from skin tissue. A testified methodology was adopted to determine melanin contents in human skin based on in vivo diffuse reflectance spectra. The rebuild diffuse reflectance spectra were investigated by adding melanin into different layers of the theoretical model. One of in vivo reflectance spectra from Junctional nevi and their surrounding normal skin was studied by compare the ratio between nevus and normal skin tissue in both the experimental and simulated diffuse reflectance spectra. The simulation result showed a good agreement with our clinical measurements, which indicated that our research method, including the spectral ratio method, skin optical model and modifying the melanin content in the model, could be applied in further theoretical simulation of pigmented skin lesions.

Polarimetric glucose sensing using Brewster reflection applying a rotating retarder analyzer

NASA Astrophysics Data System (ADS)

Boeckle, Stefan; Rovati, Luigi L.; Ansari, Rafat R.

2003-10-01

Previously, we proposed a polarimetric method, that exploits the Brewster-reflection with the final goal of application to the human eye (reflection off the eye lens) for non-invasive glucose sensing. The linearly polarized reflected light of this optical scheme is rotated by the glucose molecules present in the aqueous humor, thus carries the blood glucose concentration information. A proof-of-concept experimental bench-top setup is presented, applying a multi-wavelength true phase measurement approach and a rotating phase retarder as an analyzer to measure the very small rotation angles and the complete polarization state of the measurement light.

Digital Holography, a metrological tool for quantitative analysis: Trends and future applications

NASA Astrophysics Data System (ADS)

Paturzo, Melania; Pagliarulo, Vito; Bianco, Vittorio; Memmolo, Pasquale; Miccio, Lisa; Merola, Francesco; Ferraro, Pietro

2018-05-01

A review on the last achievements of Digital Holography is reported in this paper, showing that this powerful method can be a key metrological tool for the quantitative analysis and non-invasive inspection of a variety of materials, devices and processes. Nowadays, its range of applications has been greatly extended, including the study of live biological matter and biomedical applications. This paper overviews the main progresses and future perspectives of digital holography, showing new optical configurations and investigating the numerical issues to be tackled for the processing and display of quantitative data.

Comparative study of protoporphyrin IX fluorescence image enhancement methods to improve an optical imaging system for oral cancer detection

NASA Astrophysics Data System (ADS)

Jiang, Ching-Fen; Wang, Chih-Yu; Chiang, Chun-Ping

2011-07-01

Optoelectronics techniques to induce protoporphyrin IX fluorescence with topically applied 5-aminolevulinic acid on the oral mucosa have been developed to noninvasively detect oral cancer. Fluorescence imaging enables wide-area screening for oral premalignancy, but the lack of an adequate fluorescence enhancement method restricts the clinical imaging application of these techniques. This study aimed to develop a reliable fluorescence enhancement method to improve PpIX fluorescence imaging systems for oral cancer detection. Three contrast features, red-green-blue reflectance difference, R/B ratio, and R/G ratio, were developed first based on the optical properties of the fluorescence images. A comparative study was then carried out with one negative control and four biopsy confirmed clinical cases to validate the optimal image processing method for the detection of the distribution of malignancy. The results showed the superiority of the R/G ratio in terms of yielding a better contrast between normal and neoplastic tissue, and this method was less prone to errors in detection. Quantitative comparison with the clinical diagnoses in the four neoplastic cases showed that the regions of premalignancy obtained using the proposed method accorded with the expert's determination, suggesting the potential clinical application of this method for the detection of oral cancer.

A noninvasive method of examination of the hemostasis system.

PubMed

Kuznik, B I; Fine, I W; Kaminsky, A V

2011-09-01

We propose a noninvasive method of in vivo examination the hemostasis system based on speckle pattern analysis of coherent light scattering from the skin. We compared the results of measuring basic blood coagulation parameters by conventional invasive and noninvasive methods. A strict correlation was found between the results of measurement of soluble fibrin monomer complexes, international normalized ratio (INR), prothrombin index, and protein C content. The noninvasive method of examination of the hemostatic system enable rough evaluation of the intensity of the intravascular coagulation and correction of the dose of indirect anticoagulants maintaining desired values of INR or prothrombin index.

Noninvasive Monitoring of Blood Glucose with Raman Spectroscopy.

PubMed

Pandey, Rishikesh; Paidi, Santosh Kumar; Valdez, Tulio A; Zhang, Chi; Spegazzini, Nicolas; Dasari, Ramachandra Rao; Barman, Ishan

2017-02-21

The successful development of a noninvasive blood glucose sensor that can operate reliably over sustained periods of time has been a much sought after but elusive goal in diabetes management. Since diabetes has no well-established cure, control of elevated glucose levels is critical for avoiding severe secondary health complications in multiple organs including the retina, kidney and vasculature. While fingerstick testing continues to be the mainstay of blood glucose detection, advances in electrochemical sensing-based minimally invasive approaches have opened the door for alternate methods that would considerably improve the quality of life for people with diabetes. In the quest for better sensing approaches, optical technologies have surfaced as attractive candidates as researchers have sought to exploit the endogenous contrast of glucose, notably its absorption, scattering, and polarization properties. Vibrational spectroscopy, especially spontaneous Raman scattering, has exhibited substantial promise due to its exquisite molecular specificity and minimal interference of water in the spectral profiles acquired from the blood-tissue matrix. Yet, it has hitherto been challenging to leverage the Raman scattering signatures of glucose for prediction in all but the most basic studies and under the least demanding conditions. In this Account, we discuss the newly developed array of methodologies that address the key challenges in measuring blood glucose accurately using Raman spectroscopy and unlock new prospects for translation to sustained noninvasive measurements in people with diabetes. Owing to the weak intensity of spontaneous Raman scattering, recent research has focused on enhancement of signals from the blood constituents by designing novel excitation-collection geometries and tissue modulation methods while our attempts have led to the incorporation of nonimaging optical elements. Additionally, invoking mass transfer modeling into chemometric algorithms has not only addressed the physiological lag between the actual blood glucose and the measured interstitial fluid glucose values but also offered a powerful tool for predictive measurements of hypoglycemia. This framework has recently been extended to provide longitudinal tracking of glucose concentration without necessitating extensive a priori concentration information. These findings are advanced by the results of recent glucose tolerance studies in human subjects, which also hint at the need for designing nonlinear calibration models that can account for subject-to-subject variations in skin heterogeneity and hematocrit levels. Together, the emerging evidence underscores the promise of a blood withdrawal-free optical platform-featuring a combination of high-throughput Raman spectroscopic instrumentation and data analysis of subtle variations in spectral expression-for diabetes screening in the clinic and, ultimately, for personalized monitoring.

Spectroscopic Chemical Analysis Methods and Apparatus

NASA Technical Reports Server (NTRS)

Hug, William F. (Inventor); Lane, Arthur L. (Inventor); Bhartia, Rohit (Inventor); Reid, Ray D. (Inventor)

2017-01-01

Spectroscopic chemical analysis methods and apparatus are disclosed which employ deep ultraviolet (e.g. in the 200 nm to 300 nm spectral range) electron beam pumped wide bandgap semiconductor lasers, incoherent wide bandgap semiconductor light emitting devices, and hollow cathode metal ion lasers to perform non-contact, non-invasive detection of unknown chemical analytes. These deep ultraviolet sources enable dramatic size, weight and power consumption reductions of chemical analysis instruments. In some embodiments, Raman spectroscopic detection methods and apparatus use ultra-narrow-band angle tuning filters, acousto-optic tuning filters, and temperature tuned filters to enable ultra-miniature analyzers for chemical identification. In some embodiments Raman analysis is conducted along with photoluminescence spectroscopy (i.e. fluorescence and/or phosphorescence spectroscopy) to provide high levels of sensitivity and specificity in the same instrument.

Spectroscopic Chemical Analysis Methods and Apparatus

NASA Technical Reports Server (NTRS)

Hug, William F. (Inventor); Lane, Arthur L. (Inventor); Reid, Ray D. (Inventor); Bhartia, Rohit (Inventor)

2018-01-01

Spectroscopic chemical analysis methods and apparatus are disclosed which employ deep ultraviolet (e.g. in the 200 nm to 300 nm spectral range) electron beam pumped wide bandgap semiconductor lasers, incoherent wide bandgap semiconductor light emitting devices, and hollow cathode metal ion lasers to perform non-contact, non-invasive detection of unknown chemical analytes. These deep ultraviolet sources enable dramatic size, weight and power consumption reductions of chemical analysis instruments. In some embodiments, Raman spectroscopic detection methods and apparatus use ultra-narrow-band angle tuning filters, acousto-optic tuning filters, and temperature tuned filters to enable ultra-miniature analyzers for chemical identification. In some embodiments Raman analysis is conducted along with photoluminescence spectroscopy (i.e. fluorescence and/or phosphorescence spectroscopy) to provide high levels of sensitivity and specificity in the same instrument.

Quantitative and simultaneous non-invasive measurement of skin hydration and sebum levels

PubMed Central

Ezerskaia, Anna; Pereira, S. F.; Urbach, H. Paul; Verhagen, Rieko; Varghese, Babu

2016-01-01

We report a method on quantitative and simultaneous non-contact in-vivo hydration and sebum measurements of the skin using an infrared optical spectroscopic set-up. The method utilizes differential detection with three wavelengths 1720, 1750, and 1770 nm, corresponding to the lipid vibrational bands that lay “in between” the prominent water absorption bands. We have used an emulsifier containing hydro- and lipophilic components to mix water and sebum in various volume fractions which was applied to the skin to mimic different oily-dry skin conditions. We also measured the skin sebum and hydration values on the forehead under natural conditions and its variations to external stimuli. Good agreement was found between our experimental results and reference values measured using conventional biophysical methods such as Corneometer and Sebumeter. PMID:27375946

Noncontact measurement of heart rate using facial video illuminated under natural light and signal weighted analysis.

PubMed

Yan, Yonggang; Ma, Xiang; Yao, Lifeng; Ouyang, Jianfei

2015-01-01

Non-contact and remote measurements of vital physical signals are important for reliable and comfortable physiological self-assessment. We presented a novel optical imaging-based method to measure the vital physical signals. Using a digital camera and ambient light, the cardiovascular pulse waves were extracted better from human color facial videos correctly. And the vital physiological parameters like heart rate were measured using a proposed signal-weighted analysis method. The measured HRs consistent with those measured simultaneously with reference technologies (r=0.94, p<0.001 for HR). The results show that the imaging-based method is suitable for measuring the physiological parameters, and provide a reliable and comfortable measurement mode. The study lays a physical foundation for measuring multi-physiological parameters of human noninvasively.

Optical Spectroscopy and Imaging for the Noninvasive Evaluation of Engineered Tissues

PubMed Central

Rice, William L.; Hronik-Tupaj, Marie; Kaplan, David L.

2008-01-01

Optical spectroscopy and imaging approaches offer the potential to noninvasively assess different aspects of the cellular, extracellular matrix, and scaffold components of engineered tissues. In addition, the combination of multiple imaging modalities within a single instrument is highly feasible, allowing acquisition of complementary information related to the structure, organization, biochemistry, and physiology of the sample. The ability to characterize and monitor the dynamic interactions that take place as engineered tissues develop promises to enhance our understanding of the interdependence of processes that ultimately leads to functional tissue outcomes. It is expected that this information will impact significantly upon our abilities to optimize the design of biomaterial scaffolds, bioreactors, and cell systems. Here, we review the principles and performance characteristics of the main methodologies that have been exploited thus far, and we present examples of corresponding tissue engineering studies. PMID:18844604

Low-Coherence Reflectometry for Refractive Index Measurements of Cells in Micro-Capillaries.

PubMed

Carpignano, Francesca; Rigamonti, Giulia; Mazzini, Giuliano; Merlo, Sabina

2016-10-11

The refractive index of cells provides insights into their composition, organization and function. Moreover, a good knowledge of the cell refractive index would allow an improvement of optical cytometric and diagnostic systems. Although interferometric techniques undoubtedly represent a good solution for quantifying optical path variation, obtaining the refractive index of a population of cells non-invasively remains challenging because of the variability in the geometrical thickness of the sample. In this paper, we demonstrate the use of infrared low-coherence reflectometry for non-invasively quantifying the average refractive index of cell populations gently confined in rectangular glass micro-capillaries. A suspension of human red blood cells in plasma is tested as a reference. As a use example, we apply this technique to estimate the average refractive index of cell populations belonging to epithelial and hematological families.

In vivo imaging of human labial glands using advanced optical coherence tomography.

PubMed

Ozawa, Nobuyoshi; Sumi, Yasunori; Shimozato, Kazuo; Chong, Changho; Kurabayashi, Tohru

2009-09-01

Optical coherence tomography (OCT) has emerged as a high-resolution noninvasive clinical imaging application. The purpose of this study was to show OCT images of human labial glands obtained using a swept-source (SS) OCT system. Labial gland OCT imaging was carried out using our new SS-OCT system for 5 healthy volunteers using a hand-held in vivo OCT scanning probe. The labial tissue was scanned in a superior to inferior direction in 2 and 3 dimensions. The resulting 2- and 3-dimensional ultrahigh-resolution images of in vivo OCT human labial minor salivary glands revealed the epithelium, connective tissue, lobes, and duct. OCT was capable of providing simultaneous and noninvasive structural information with high resolution. This clinical imaging modality promises to have clinical impact in the diagnosis of such conditions as Sjögren syndrome and xerostomia.

Effect of Injector Geometry on Atomization of a Liquid-Liquid Double Swirl Coaxial Injector Using Non-invasive Laser, Optical and X-ray Techniques

NASA Technical Reports Server (NTRS)

Radke, C. R.; Meyer, T. R.

2014-01-01

The spray characteristics of a liquid-liquid double swirl coaxial injector were studied using non-invasive optical, laser, and X-ray diagnostics. A parametric study of injector exit geometry demonstrated that spray breakup time, breakup type and sheet stability could be controlled with exit geometry. Phase Doppler interferometry was used to characterize droplet statistics and non-dimensional droplet parameters over a range of inlet conditions and for various fluids allowing for a study on the role of specific fluid properties in atomization. Further, X-ray radiography allowed for investigation of sheet thickness and breakup length to be quantified for different recess exit diameters and inlet pressures. Finally, computed tomography scans revealed that the spray cone was distinctively non-uniform and comprised of several pockets of increased mass flux.

Effect of Injector Geometry on Atomization of a Liquid-Liquid Double Swirl Coaxial Injector using Non-Invasive Laser, Optical and X-ray Techniques

NASA Technical Reports Server (NTRS)

Radke, C. R.; Meyer, T. R.

2014-01-01

The spray characteristics of a Liquid-Liquid Double Swirl Coaxial Injector were studied using noninvasive Optical, Laser, and X-ray diagnostics. A parametric study of injector exit geometry demonstrated that spray breakup time, breakup type and sheet stability could be controlled with exit geometry. Phase Doppler Particle Analysis characterized droplet statistics and non-dimensional droplet parameters over a range of inlet conditions and for various fluids allowing for a study on the role of specific fluid properties in atomization. Further, x-ray radiographs allowed for investigations of sheet thickness and breakup length to be quantified for different recess exits and inlet pressures. Finally Computed Tomography scans revealed that the spray cone was distinctively non-uniform and comprised of several pockets of increased mass flux.

Low-Coherence Reflectometry for Refractive Index Measurements of Cells in Micro-Capillaries

PubMed Central

Carpignano, Francesca; Rigamonti, Giulia; Mazzini, Giuliano; Merlo, Sabina

2016-01-01

The refractive index of cells provides insights into their composition, organization and function. Moreover, a good knowledge of the cell refractive index would allow an improvement of optical cytometric and diagnostic systems. Although interferometric techniques undoubtedly represent a good solution for quantifying optical path variation, obtaining the refractive index of a population of cells non-invasively remains challenging because of the variability in the geometrical thickness of the sample. In this paper, we demonstrate the use of infrared low-coherence reflectometry for non-invasively quantifying the average refractive index of cell populations gently confined in rectangular glass micro-capillaries. A suspension of human red blood cells in plasma is tested as a reference. As a use example, we apply this technique to estimate the average refractive index of cell populations belonging to epithelial and hematological families. PMID:27727172

Study of UV imaging technology for noninvasive detection of latent fingerprints

NASA Astrophysics Data System (ADS)

Li, Hong-xia; Cao, Jing; Niu, Jie-qing; Huang, Yun-gang

2013-09-01

Using UV imaging technology, according to the special absorption 、reflection 、scattering and fluorescence characterization of the various residues in fingerprints (fatty acid ester, protein, and carboxylic acid salts etc) to the UV light, weaken or eliminate the background disturbance to increase the brightness contrast of fingerprints with the background, and design、setup the illumination optical system and UV imaging system, the noninvasive detection of latent fingerprints remaining on various object surface are studied. In the illumination optical system, using the 266nm UV Nd:YAG solid state laser as illumination light source, by calculating the best coupling conditions of the laser beam with UV liquid core fiber and analyzing the beam transforming characterizations, we designed and setup the optical system to realize the UV imaging uniform illumination. In the UV imaging system, the UV lens is selected as the fingerprint imaging element, and the UV intensified CCD (ICCD) which consists of a second-generation UV image intensifier and a CCD coupled by fiber plate and taper directly are used as the imaging sensing element. The best imaging conditions of the UV lens with ICCD were analyzed and the imaging system was designed and setup. In this study, by analyzing the factors which influence the detection effect, optimal design and setup the illumination system and imaging system, latent fingerprints on the surface of the paint tin box、plastic、smooth paper、notebook paper and print paper were noninvasive detected and appeared, and the result meet the fingerprint identification requirements in forensic science.

Retinal angiography with real-time speckle variance optical coherence tomography.

PubMed

Xu, Jing; Han, Sherry; Balaratnasingam, Chandrakumar; Mammo, Zaid; Wong, Kevin S K; Lee, Sieun; Cua, Michelle; Young, Mei; Kirker, Andrew; Albiani, David; Forooghian, Farzin; Mackenzie, Paul; Merkur, Andrew; Yu, Dao-Yi; Sarunic, Marinko V

2015-10-01

This report describes a novel, non-invasive and label-free optical imaging technique, speckle variance optical coherence tomography (svOCT), for visualising blood flow within human retinal capillary networks. This imaging system uses a custom-built swept source OCT system operating at a line rate of 100 kHz. Real-time processing and visualisation is implemented on a consumer grade graphics processing unit. To investigate the quality of microvascular detail acquired with this device we compared images of human capillary networks acquired with svOCT and fluorescein angiography. We found that the density of capillary microvasculature acquired with this svOCT device was visibly greater than fluorescein angiography. We also found that this svOCT device had the capacity to generate en face images of distinct capillary networks that are morphologically comparable with previously published histological studies. Finally, we found that this svOCT device has the ability to non-invasively illustrate the common manifestations of diabetic retinopathy and retinal vascular occlusion. The results of this study suggest that graphics processing unit accelerated svOCT has the potential to non-invasively provide useful quantitative information about human retinal capillary networks. Therefore svOCT may have clinical and research applications for the management of retinal microvascular diseases, which are a major cause of visual morbidity worldwide. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Optogenetic pacing in Drosophila melanogaster

PubMed Central

Alex, Aneesh; Li, Airong; Tanzi, Rudolph E.; Zhou, Chao

2015-01-01

Electrical stimulation is currently the gold standard for cardiac pacing. However, it is invasive and nonspecific for cardiac tissues. We recently developed a noninvasive cardiac pacing technique using optogenetic tools, which are widely used in neuroscience. Optogenetic pacing of the heart provides high spatial and temporal precisions, is specific for cardiac tissues, avoids artifacts associated with electrical stimulation, and therefore promises to be a powerful tool in basic cardiac research. We demonstrated optogenetic control of heart rhythm in a well-established model organism, Drosophila melanogaster. We developed transgenic flies expressing a light-gated cation channel, channelrhodopsin-2 (ChR2), specifically in their hearts and demonstrated successful optogenetic pacing of ChR2-expressing Drosophila at different developmental stages, including the larva, pupa, and adult stages. A high-speed and ultrahigh-resolution optical coherence microscopy imaging system that is capable of providing images at a rate of 130 frames/s with axial and transverse resolutions of 1.5 and 3.9 μm, respectively, was used to noninvasively monitor Drosophila cardiac function and its response to pacing stimulation. The development of a noninvasive integrated optical pacing and imaging system provides a novel platform for performing research studies in developmental cardiology. PMID:26601299

Newly developed photon-cell interactive Monte Carlo (pciMC) simulation for non-invasive and continuous diagnosis of blood during extracorporeal circulation support

NASA Astrophysics Data System (ADS)

Sakota, Daisuke; Takatani, Setsuo

2011-07-01

We have sought for non-invasive diagnosis of blood during the extracorporeal circulation support. To achieve the goal, we have newly developed a photon-cell interactive Monte Carlo (pciMC) model for optical propagation through blood. The pciMC actually describes the interaction of photons with 3-dimentional biconcave RBCs. The scattering is described by micro-scopical RBC boundary condition based on geometric optics. By using pciMC, we modeled the RBCs inside the extracorporeal circuit will be oriented by the blood flow. The RBCs' orientation was defined as their long axis being directed to the center of the circulation tube. Simultaneously the RBCs were allowed to randomly rotate about the long axis direction. As a result, as flow rate increased, the orientation rate increased and converged to approximately 22% at 0.5 L/min flow rate and above. And finally, by using this model, the pciMC non-invasively and absolutely predicted Hct and hemoglobin with the accuracies of 0.84+/-0.82 [HCT%] and 0.42+/-0.28 [g/dL] respectively against measurements by a blood gas analyzer.

Monitoring early tumor response to drug therapy with diffuse optical tomography

NASA Astrophysics Data System (ADS)

Flexman, Molly L.; Vlachos, Fotios; Kim, Hyun Keol; Sirsi, Shashank R.; Huang, Jianzhong; Hernandez, Sonia L.; Johung, Tessa B.; Gander, Jeffrey W.; Reichstein, Ari R.; Lampl, Brooke S.; Wang, Antai; Borden, Mark A.; Yamashiro, Darrell J.; Kandel, Jessica J.; Hielscher, Andreas H.

2012-01-01

Although anti-angiogenic agents have shown promise as cancer therapeutics, their efficacy varies between tumor types and individual patients. Providing patient-specific metrics through rapid noninvasive imaging can help tailor drug treatment by optimizing dosages, timing of drug cycles, and duration of therapy--thereby reducing toxicity and cost and improving patient outcome. Diffuse optical tomography (DOT) is a noninvasive three-dimensional imaging modality that has been shown to capture physiologic changes in tumors through visualization of oxygenated, deoxygenated, and total hemoglobin concentrations, using non-ionizing radiation with near-infrared light. We employed a small animal model to ascertain if tumor response to bevacizumab (BV), an anti-angiogenic agent that targets vascular endothelial growth factor (VEGF), could be detected at early time points using DOT. We detected a significant decrease in total hemoglobin levels as soon as one day after BV treatment in responder xenograft tumors (SK-NEP-1), but not in SK-NEP-1 control tumors or in non-responder control or BV-treated NGP tumors. These results are confirmed by magnetic resonance imaging T2 relaxometry and lectin perfusion studies. Noninvasive DOT imaging may allow for earlier and more effective control of anti-angiogenic therapy.

Mid-Infrared Photoacoustic Detection of Glucose in Human Skin: Towards Non-Invasive Diagnostics

PubMed Central

Kottmann, Jonas; Rey, Julien M.; Sigrist, Markus W.

2016-01-01

Diabetes mellitus is a widespread metabolic disease without cure. Great efforts are being made to develop a non-invasive monitoring of the blood glucose level. Various attempts have been made, including a number of non-optical approaches as well as optical techniques involving visible, near- and mid-infrared light. However, no true breakthrough has been achieved so far, i.e., there is no fully non-invasive monitoring device available. Here we present a new study based on mid-infrared spectroscopy and photoacoustic detection. We employ two setups, one with a fiber-coupled photoacoustic (PA) cell and a tunable quantum cascade laser (QCL), and a second setup with two QCLs at different wavelengths combined with PA detection. In both cases, the PA cells are in direct skin contact. The performance is tested with an oral glucose tolerance test. While the first setup often gives reasonable qualitative agreement with ordinary invasive blood glucose measurements, the dual-wavelength approach yields a considerably improved stability and an uncertainty of only ±30 mg/dL of the blood glucose concentration level at a confidence level of 90%. This result is achieved without advanced data treatment such as principal component analysis involving extended wavelength ranges. PMID:27735878

Laser speckle and skin cancer: skin roughness assessment

NASA Astrophysics Data System (ADS)

Lee, Tim K.; Tchvialeva, Lioudmila; Zeng, Haishan; McLean, David I.; Lui, Harvey

2009-10-01

Incidence of skin cancer has been increasing rapidly since the last few decades. Non-invasive optical diagnostic tools may improve the diagnostic accuracy. In this paper, skin structure, skin cancer statistics and subtypes of skin cancer are briefly reviewed. Among the subtypes, malignant melanoma is the most aggressive and dangerous; early detection dramatically improves the prognosis. Therefore, a non-invasive diagnostic tool for malignant melanoma is especially needed. In addition, in order for the diagnostic tool to be useful, it must be able to differentiate melanoma from common skin conditions such as seborrheic keratosis, a benign skin disease that resembles melanoma according to the well known clinical-assessment ABCD rule. The key diagnostic feature between these two diseases is surface roughness. Based on laser speckle contrast, our research team has recently developed a portable, optical, non-invasive, in-vivo diagnostic device for quantifying skin surface roughness. The methodology of our technique is described in details. Examining the preliminary data collected in a pilot clinical study for the prototype, we found that there was a difference in roughness between melanoma and seborrheic keratosis. In fact, there was a perfect cutoff value for the two diseases based on our initial data.

Spectral (optical) and mechanical responses of fresh and cryopreserved issued arteries

NASA Astrophysics Data System (ADS)

Pery, Emilie; Blondel, Walter C.; Goebel, Jean-Christophe; Didelon, Jacques; Guillemin, Francois

2005-04-01

Cryopreservation is the only method for conserving blood vessels as future allografts with biological immunity controls. Although it affects vessels mechanical structure, no biomechanical integrity simple test is available today. Biological tissues optical properties characterization by spectroscopic methods is of interest due to their types or natures variations. Collected data complementarity contributes to "photodiagnosis" applicative prospects (cancer, vascular...). Pig carotid artery rings were tested after excision and after one month cryopreservation. An uniaxial mechanical testing device was used for ring stretching, and elongation and axial forces measurement. Circumferential large strains and stresses were calculated. Simultaneously, each artery ring optical characteristics was measured using fibered autofluorescence and elastic scattering spectrometers. Mechanical results showed nonlinear strain/stress curves and large deformations in good agreement with other referenced works. Significant differences (p<0.05) between fresh and cryopreserved rings mechanical properties were noticed. Elastic scattering spectra intensity variations were well correlated with artery mechanical properties. The standardized autofluorescence spectra were more clearly correlated with anatomo-histological changes due to cryopreservation, providing rather accurate differentiation between fresh and cryopreserved samples. This study offers a new perspective to detect changes of cryopreserved arterial samples mechanical properties. Coupling mechanical tests (uniaxial traction of arterial rings) and optical spectroscopic measurements (autofluorescence, elastic scattering) is the driving point: it allows correlating mechanical modifications and spectral variations of artery rings before and after cryopreservation. Ultimately, this new approach could help developping a device allowing non-invasive, atraumatic and contactless optical examinations of arterial graft to assess its mechanical state before reimplantation.

RGC Neuroprotection Following Optic Nerve Trauma Mediated By Intranasal Delivery of Amnion Cell Secretome

PubMed Central

Grinblat, Gabriela A.; Khan, Reas S.; Dine, Kimberly; Wessel, Howard; Brown, Larry; Shindler, Kenneth S.

2018-01-01

Purpose Intranasally delivered ST266, the biological, proteinaceous secretome of amnion-derived multipotent progenitor cells, reduces retinal ganglion cell (RGC) loss, optic nerve inflammation, and demyelination in experimental optic neuritis. This unique therapy and novel administration route delivers numerous cytokines and growth factors to the eye and optic nerve, suggesting a potential to also treat other optic neuropathies. Thus, ST266-mediated neuroprotection was examined following traumatic optic nerve injury. Methods Optic nerve crush injury was surgically induced in C57BL/6J mice. Mice were treated daily with intranasal PBS or ST266. RGC function was assessed by optokinetic responses (OKRs), RGCs were counted, and optic nerve sections were stained with luxol fast blue and anti-neurofilament antibodies to assess myelin and RGC axon damage. Results Intranasal ST266 administered daily for 5 days, beginning at the time that a 1-second optic nerve crush was performed, significantly attenuated OKR decreases. Furthermore, ST266 treatment reduced damage to RGC axons and myelin within optic nerves, and blocked RGC loss. Following a 4-second optic nerve crush, intranasal ST266 increased RGC survival and showed a trend toward reduced RGC axon and myelin damage. Ten days following optic nerve crush, ST266 prevented myelin damage, while also inducing a trend toward increased RGC survival and visual function. Conclusions ST266 significantly attenuates traumatic optic neuropathy. Neuroprotective effects of this unique combination of biologic molecules observed here and previously in optic neuritis suggest potential broad application for preventing neuronal damage in multiple optic nerve disorders. Furthermore, results support intranasal delivery as a novel, noninvasive therapeutic modality for eyes and optic nerves. PMID:29847652

The fundus photo has met its match: optical coherence tomography and adaptive optics ophthalmoscopy are here to stay.

PubMed

Morgan, Jessica I W

2016-05-01

Over the past 25 years, optical coherence tomography (OCT) and adaptive optics (AO) ophthalmoscopy have revolutionised our ability to non-invasively observe the living retina. The purpose of this review is to highlight the techniques and human clinical applications of recent advances in OCT and adaptive optics scanning laser/light ophthalmoscopy (AOSLO) ophthalmic imaging. Optical coherence tomography retinal and optic nerve head (ONH) imaging technology allows high resolution in the axial direction resulting in cross-sectional visualisation of retinal and ONH lamination. Complementary AO ophthalmoscopy gives high resolution in the transverse direction resulting in en face visualisation of retinal cell mosaics. Innovative detection schemes applied to OCT and AOSLO technologies (such as spectral domain OCT, OCT angiography, confocal and non-confocal AOSLO, fluorescence, and AO-OCT) have enabled high contrast between retinal and ONH structures in three dimensions and have allowed in vivo retinal imaging to approach that of histological quality. In addition, both OCT and AOSLO have shown the capability to detect retinal reflectance changes in response to visual stimuli, paving the way for future studies to investigate objective biomarkers of visual function at the cellular level. Increasingly, these imaging techniques are being applied to clinical studies of the normal and diseased visual system. Optical coherence tomography and AOSLO technologies are capable of elucidating the structure and function of the retina and ONH noninvasively with unprecedented resolution and contrast. The techniques have proven their worth in both basic science and clinical applications and each will continue to be utilised in future studies for many years to come. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.

Instrumentation for noninvasive express-diagnostics bacteriophages and viruses by optical method

NASA Astrophysics Data System (ADS)

Moguilnaia, Tatiana A.; Andreev, Gleb I.; Agibalov, Andrey A.; Botikov, Andrey G.; Kosenkov, Evgeniy; Saguitova, Elena

2004-03-01

The theoretical and the experimental researches of spectra of absent-minded radiation in medium containing viruses were carried out. The information on spectra luminescence 31 viruses was written down.The new method the express - analysis of viruses in organism of the man was developed. It shall be mentioned that the proposed method of express diagnostics allows detection of infection agent in the organism several hours after infection. It makes it suitable for high efficient testing in blood services for detection and rejection of potential donors infected with such viruses as hepatitis, herpes, Epstein-Barre, cytomegalovirus, and immunodeficiency. Methods of serum diagnostics used for that purpose can detect antibodies to virus only 1-3 months after the person has been infected. The device for the express analysis of 31 viruses of the man was created.

Early postoperative changes in cerebral oxygen metabolism following neonatal cardiac surgery: Effects of surgical duration

PubMed Central

Buckley, Erin M.; Lynch, Jennifer M.; Goff, Donna A.; Schwab, Peter J.; Baker, Wesley B.; Durduran, Turgut; Busch, David R.; Nicolson, Susan C.; Montenegro, Lisa M.; Naim, Maryam Y.; Xiao, Rui; Spray, Thomas L.; Yodh, A. G.; Gaynor, J. William; Licht, Daniel J.

2013-01-01

Objective The early postoperative period following neonatal cardiac surgery is a time of increased risk for brain injury, yet the mechanisms underlying this risk are unknown. To understand these risks more completely, we quantified changes in postoperative cerebral metabolic rate of oxygen (CMRO2), oxygen extraction fraction (OEF), and cerebral blood flow (CBF) compared with preoperative levels by using noninvasive optical modalities. Methods Diffuse optical spectroscopy and diffuse correlation spectroscopy were used concurrently to derive cerebral blood flow and oxygen utilization postoperatively for 12 hours. Relative changes in CMRO2, OEF, and CBF were quantified with reference to preoperative data. A mixed-effect model was used to investigate the influence of total support time and deep hypothermic circulatory arrest duration on relative changes in CMRO2, OEF, and CBF. Results Relative changes in CMRO2, OEF, and CBF were assessed in 36 patients, 21 with single-ventricle defects and 15 with 2-ventricle defects. Among patients with single-ventricle lesions, deep hypothermic circulatory arrest duration did not affect relative changes in CMRO2, CBF, or OEF (P > .05). Among 2-ventricle patients, total support time was not a significant predictor of relative changes in CMRO2 or CBF (P > .05), although longer total support time was associated significantly with greater increases in relative change of postoperative OEF (P = .008). Conclusions Noninvasive diffuse optical techniques were used to quantify postoperative relative changes in CMRO2, CBF, and OEF for the first time in this observational pilot study. Pilot data suggest that surgical duration does not account for observed variability in the relative change in CMRO2, and that more comprehensive clinical studies using the new technology are feasible and warranted to elucidate these issues further. PMID:23111021

Comparison of optical and power Doppler ultrasound imaging for non-invasive evaluation of arsenic trioxide as a vascular disrupting agent in tumors.

PubMed

Alhasan, Mustafa K; Liu, Li; Lewis, Matthew A; Magnusson, Jennifer; Mason, Ralph P

2012-01-01

Small animal imaging provides diverse methods for evaluating tumor growth and acute response to therapy. This study compared the utility of non-invasive optical and ultrasound imaging to monitor growth of three diverse human tumor xenografts (brain U87-luc-mCherry, mammary MCF7-luc-mCherry, and prostate PC3-luc) growing in nude mice. Bioluminescence imaging (BLI), fluorescence imaging (FLI), and Power Doppler ultrasound (PD US) were then applied to examine acute vascular disruption following administration of arsenic trioxide (ATO).During initial tumor growth, strong correlations were found between manual caliper measured tumor volume and FLI intensity, BLI intensity following luciferin injection, and traditional B-mode US. Administration of ATO to established U87 tumors caused significant vascular shutdown within 2 hrs at all doses in the range 5 to 10 mg/kg in a dose dependant manner, as revealed by depressed bioluminescent light emission. At lower doses substantial recovery was seen within 4 hrs. At 8 mg/kg there was >85% reduction in tumor vascular perfusion, which remained depressed after 6 hrs, but showed some recovery after 24 hrs. Similar response was observed in MCF7 and PC3 tumors. Dynamic BLI and PD US each showed similar duration and percent reductions in tumor blood flow, but FLI showed no significant changes during the first 24 hrs.The results provide further evidence for comparable utility of optical and ultrasound imaging for monitoring tumor growth, More specifically, they confirm the utility of BLI and ultrasound imaging as facile assays of the vascular disruption in solid tumors based on ATO as a model agent.

Cortical light scattering during interictal epileptic spikes in frontal lobe epilepsy in children: A fast optical signal and electroencephalographic study.

PubMed

Manoochehri, Mana; Mahmoudzadeh, Mahdi; Bourel-Ponchel, Emilie; Wallois, Fabrice

2017-12-01

Interictal epileptic spikes (IES) represent a signature of the transient synchronous and excessive discharge of a large ensemble of cortical heterogeneous neurons. Epilepsy cannot be reduced to a hypersynchronous activation of neurons whose functioning is impaired, resulting on electroencephalogram (EEG) in epileptic seizures or IES. The complex pathophysiological mechanisms require a global approach to the interactions between neural synaptic and nonsynaptic, vascular, and metabolic systems. In the present study, we focused on the interaction between synaptic and nonsynaptic mechanisms through the simultaneous noninvasive multimodal multiscale recording of high-density EEG (HD-EEG; synaptic) and fast optical signal (FOS; nonsynaptic), which evaluate rapid changes in light scattering related to changes in membrane configuration occurring during neuronal activation of IES. To evaluate changes in light scattering occurring around IES, three children with frontal IES were simultaneously recorded with HD-EEG and FOS. To evaluate change in synchronization, time-frequency representation analysis of the HD-EEG was performed simultaneously around the IES. To independently evaluate our multimodal method, a control experiment with somatosensory stimuli was designed and applied to five healthy volunteers. Alternating increase-decrease-increase in optical signals occurred 200 ms before to 180 ms after the IES peak. These changes started before any changes in EEG signal. In addition, time-frequency domain EEG analysis revealed alternating decrease-increase-decrease in the EEG spectral power concomitantly with changes in the optical signal during IES. These results suggest a relationship between (de)synchronization and neuronal volume changes in frontal lobe epilepsy during IES. These changes in the neuronal environment around IES in frontal lobe epilepsy observed in children, as they have been in rats, raise new questions about the synaptic/nonsynaptic mechanisms that propel the neurons to hypersynchronization, as occurs during IES. We further demonstrate that this noninvasive multiscale multimodal approach is suitable for studying the pathophysiology of the IES in patients. Wiley Periodicals, Inc. © 2017 International League Against Epilepsy.

In vivo imaging of endogenous neural stem cells in the adult brain

PubMed Central

Rueger, Maria Adele; Schroeter, Michael

2015-01-01

The discovery of endogenous neural stem cells (eNSCs) in the adult mammalian brain with their ability to self-renew and differentiate into functional neurons, astrocytes and oligodendrocytes has raised the hope for novel therapies of neurological diseases. Experimentally, those eNSCs can be mobilized in vivo, enhancing regeneration and accelerating functional recovery after, e.g., focal cerebral ischemia, thus constituting a most promising approach in stem cell research. In order to translate those current experimental approaches into a clinical setting in the future, non-invasive imaging methods are required to monitor eNSC activation in a longitudinal and intra-individual manner. As yet, imaging protocols to assess eNSC mobilization non-invasively in the live brain remain scarce, but considerable progress has been made in this field in recent years. This review summarizes and discusses the current imaging modalities suitable to monitor eNSCs in individual experimental animals over time, including optical imaging, magnetic resonance tomography and-spectroscopy, as well as positron emission tomography (PET). Special emphasis is put on the potential of each imaging method for a possible clinical translation, and on the specificity of the signal obtained. PET-imaging with the radiotracer 3’-deoxy-3’-[18F]fluoro-L-thymidine in particular constitutes a modality with excellent potential for clinical translation but low specificity; however, concomitant imaging of neuroinflammation is feasible and increases its specificity. The non-invasive imaging strategies presented here allow for the exploitation of novel treatment strategies based upon the regenerative potential of eNSCs, and will help to facilitate a translation into the clinical setting. PMID:25621107

Microfabricated endoscopic probe integrated MEMS micromirror for optical coherence tomography bioimaging.

PubMed

Wang, Ming-Fang; Xu, Yingshun; Prem, C S; Chen, Kelvin Wei Sheng; Xie, Jin; Mu, Xiaojing; Tan, Chee Wei; Yu, Aibin; Feng, Hanhua

2010-01-01

In this paper, we present a miniaturized endoscopic probe, consisted of MEMS micromirror, silicon optical bench (SiOB), grade index (GRIN) lens, single mode optical fiber (SMF) and transparent housing, for optical coherence tomography (OCT) bioimaging. Due to the use of the MEMS micromirror, the endoscopic OCT system is highly suitable for non-invasive imaging diagnosis of a wide variety of inner organs. The probe engineering and proof of concept were demonstrated by obtaining the two-dimensional OCT images with a cover slide and an onion used as standard samples and the axial resolution was around 10µm.

Optical Coherence Tomography

PubMed Central

Huang, David; Swanson, Eric A.; Lin, Charles P.; Schuman, Joel S.; Stinson, William G.; Chang, Warren; Hee, Michael R.; Flotte, Thomas; Gregory, Kenton; Puliafito, Carmen A.; Fujimoto, James G.

2015-01-01

A technique called optical coherence tomography (OCT) has been developed for noninvasive cross-sectional imaging in biological systems. OCT uses low-coherence interferometry to produce a two-dimensional image of optical scattering from internal tissue microstructures in a way that is analogous to ultrasonic pulse-echo imaging. OCT has longitudinal and lateral spatial resolutions of a few micrometers and can detect reflected signals as small as ~10−10 of the incident optical power. Tomographic imaging is demonstrated in vitro in the peripapillary area of the retina and in the coronary artery, two clinically relevant examples that are representative of transparent and turbid media, respectively. PMID:1957169

Doppler Optical Coherence Tomography

NASA Astrophysics Data System (ADS)

Chen, Zhongping; Zhang, Jun

Noninvasive techniques for imaging in vivo blood flow are of great value to biomedical research and clinical diagnostics where many diseases have a vascular etiology or component. In ophthalmology, many diseases involve disturbances in ocular blood flow, including diabetic retinopathy, low tension glaucoma, anterior ischemic optic neuritis, and macular degeneration. Simultaneous imaging of tissue structure and blood flow could provide critical information for early diagnosis of ocular diseases.

Optical second-harmonic-generation probe of two-dimensional ferroelectricity.

PubMed

Aktsipetrov, O A; Misuryaev, T V; Murzina, T V; Blinov, L M; Fridkin, V M; Palto, S P

2000-03-15

Optical second-harmonic generation (SHG) is used as a noninvasive probe of two-dimensional (2D) ferroelectricity in Langmuir-Blodgett (LB) films of the copolymer vinylidene fluoride with trifluoroethylene. The surface 2D ferroelectric-paraelectric phase transition in the topmost layer of the LB films and a thickness-independent (almost 2D) transition in the bulk of these films are observed in temperature studies of SHG.

High energy photons excited photodynamic cancer therapy in vitro

NASA Astrophysics Data System (ADS)

Guo, Yiping; Sheng, Shi; Zhang, Wei; Lun, Michael; Tsai, Shih-Ming; Chin, Wei-Chun; Hoglund, Roy; Li, Changqing

2018-02-01

Photodynamic therapy (PDT) is a noninvasive phototherapy method that has been clinically approved for many years. During this type of therapy, the photosensitizing agent will be excited by optical photons to generate reactive oxygen species which can kill nearby cancer cells. However, due to the strong optical scattering and absorption of tissue, optical photons can only penetrate tissues in few millimeters which result in the limited applications of PDT to superficial lesions like skin cancers. In this study, to overcome the penetration limitations, we used high-energy photons to excite photosensitizers directly by assuming that high-energy photons generate low-energy optical photons in tissues to excite photosensitizers. Cesium- 137 irradiator has been used as the high-energy photon source. A fiber pigtailed diode laser was used to validate the photosensitizer's efficacy. We used MPPa as the photosensitizer to treat A549 cancer cell line with different concentrations of drug (10μM/ ml, 5 μM/ml, 2.5 μM/ml, 1 μM/ml and 0 μM/ml). We have performed an irradiation experiment for different time durations of 30 min, 15 min, 7 min to 3 min, respectively, and we also compared different drug concentrations and different exposure durations. Our study not only proved the MPPa PDT method was effective, but also indicated that high-energy photons enhanced PDT could potentially overcome the penetration limitations thus making PDT feasible for deep tissue cancer.

Application of Optical Imaging Techniques for Quantification of pH and O2 Dynamicsin Porous Media

NASA Astrophysics Data System (ADS)

Li, B.; Seliman, A. F.; Pales, A. R.; Liang, W.; Sams, A.; Darnault, C. J. G.; DeVol, T. A.

2016-12-01

Understanding the spatial and temporal distribution of physical and chemical parameters (e.g. pH, O2) is imperative to characterize the behavior of contaminants in a natural environment. The objectives of this research are to calibrate pH and O2 sensor foils, to develop a dual pH/O2 sensor foil, and to apply them into flow and transport experiments, in order to understand the physical and chemical parameters that control contaminant fate and transport in an unsaturated sandy porous medium. In addition, demonstration of a sensor foil that quantifies aqueous uranium concentration will be presented. Optical imaging techniques will be conducted with 2D tanks to investigate the influence of microbial exudates and plant roots on pH and O2 parameters and radionuclides transport. As a non-invasive method, the optical imaging technique utilizes optical chemical sensor films and either a digital camera or a spectrometer to capture the changes with high temporal and spatial resolutions. Sensor foils are made for different parameters by applying dyes to generate favorable fluorescence that is proportional to the parameter of interest. Preliminary results suggested that this method could detect pH ranging from 4.5 to 7.5. The result from uranium foil test with different concentrations in the range of 2 to 8 ppm indicated that a higher concentration of uranium resulted in a greater color intensity.

Development and Application of Multifunctional Optical Coherence Tomography

NASA Astrophysics Data System (ADS)

Zhi, Zhongwei

Microcirculation refers to the functions of capillaries and the neighboring lymphatic vessels. It plays a vital role in the pathophysiology of disorders in many clinical areas including cardiology, dermatology, neurology and ophthalmology, and so forth. It is crucial to develop imaging technologies that can provide both qualitative and quantitative information as to how microcirculation responds to certain injury and/or disease, and its treatment. Optical coherence tomography (OCT) is a non-invasive optical imaging technique for high-resolution cross-sectional imaging of specimens, with many applications in clinical medicine. Current state-of-the-art OCT systems operate in the Fourier domain, using either a broadband light source with a spectrometer, known as spectral domain OCT (SDOCT), or a rapidly tunable laser, known as swept source OCT (SSOCT). The current Fourier domain OCT systems have dramatically improvement in sensitivity, resolution and speed compared to time domain OCT. In addition to the improvement in the OCT system hardware, different methods for functional measurements of tissue beds have been developed and demonstrated. This includes but not limited to, i) Phase-resolved Doppler OCT for quantifying the blood flow, ii) OCT angiography for visualization of microvasculature, iii) Polarization sensitive OCT for measuring the intrinsic optical property/ birefringence of tissue, iv) spectroscopic OCT for measuring blood oxygenation, etc. Functional OCT can provide important clinical information that is not available in the typical intensity based structural OCT images. Among these functional OCT modalities, Doppler OCT and OCT angiography attract great interests as they show high capability for in vivo study of microvascular pathology. By analyzing the Doppler effect of a flowing particle on light frequency, Doppler OCT allows the quantification of the blood flow speed and blood flow rate. The most popular approach for Doppler OCT is achieved through analysis of the phase term in complex OCT signal which termed as Phase-resolved Doppler OCT. However, as limited by the phase noise and motion, Phase-resolved Doppler OCT can only be applied for relative large blood vessels, such as arterioles and venules. On the other hand, in order to visualize the microcirculation network, a number of strategies to enable better contrast of microvasculature components, which we termed OCT angiography, have been introduced during recent years. As a variation of Fourier domain OCT, optical microangiography (OMAG) is one of earliest proposed OCT angiography technique which is capable of generating 3D images of dynamic blood perfusion distribution within microcirculatory tissue beds. The OMAG algorithm works by separating the static and moving elements by high pass filtering on complex valued interferometric data after Fourier transform. Based on the conventional OMAG algorithm, we further developed ultra-high sensitive OMAG (UHS-OMAG) by switching the high-pass filtering from fast scan direction (adjacent A-lines within one B-frame) to slow scan direction (adjacent B-frames), which has a dramatically improved performance for capillary network imaging and analysis. Apart from the microvascular study with current available functional OCT for, visualization of the lymphatic system (lymph nodes and lymphatic vessels) plays a significant role in assessing patients with various malignancies and lymphedema. However, there is a lack of label-free and noninvasive method for lymphangiography. Hence, a cutting edge research to investigate the capability of OCT as a tool for non-invasive and label-free lymphangiography would be highly desired. The objective of my thesis is to develop a multiple-functional SDOCT system to image the microcirculation and quantify the several important parameters of microcirculation within microcirculatory tissue beds, and further apply it for pre-clinical research applications. The multifunctional OCT system provides modalities including structural OCT, OCT angiography, Doppler OCT and Optical lymphangiography, for multi-parametric study of tissue microstructure, blood vessel morphology, blood flow and lymphatic vessel all together. The thesis mainly focus on two parts: first, development of multi-functional OCT/optical microangiography (OMAG) system and methods for volumetric imaging of microvasculature and quantitative measurement of blood flow, and its application for pathological research in ophthalmology on rodent eye models; second, development of ultra-high resolution OCT system and algorithm for simultaneous label free imaging of blood and lymphatic vessel, and its application in wound healing study on mouse ear flap model. Objectives of my research are achieved through the following specific aims: Aim 1: Improve the sensitivity of OMAG for microvasculature imaging; perform volumetric and quantitative imaging of vasculature with combined OMAG and Phase-resolved Doppler OCT for in vivo study of vascular physiology. Aim 2: Develop high speed high resolution OCT system and method for rodent eye imaging. Apply the combined OMAG and Phase-resolved Doppler OCT approach to investigate the impact of elevated intraocular pressure on retinal, choroidal and optic nerve head blood flow in rat eye model, which aids to the better understanding of the mechanism and development of glaucoma. Aim 3: Apply the developed OCT system and ultra-high sensitive OMAG algorithm for noninvasive imaging of retinal morphology and microvasculature in obese mice, which may play an important role in early diagnosis of Diabetic retinopathy. Aim 4: Developing an ultra-high resolution SDOCT system using broadband Supercontinuum light source to achieve ultra-high resolution microvasculature imaging of biological tissue. Aim 5: Develop methods for simultaneous label free optical imaging of blood and lymphatic vessel and demonstrate its capability by monitoring the blood and lymph response to wound healing on mouse ear pinna model.

Microscopic optical path length difference and polarization measurement system for cell analysis

NASA Astrophysics Data System (ADS)

Satake, H.; Ikeda, K.; Kowa, H.; Hoshiba, T.; Watanabe, E.

2018-03-01

In recent years, noninvasive, nonstaining, and nondestructive quantitative cell measurement techniques have become increasingly important in the medical field. These cell measurement techniques enable the quantitative analysis of living cells, and are therefore applied to various cell identification processes, such as those determining the passage number limit during cell culturing in regenerative medicine. To enable cell measurement, we developed a quantitative microscopic phase imaging system based on a Mach-Zehnder interferometer that measures the optical path length difference distribution without phase unwrapping using optical phase locking. The applicability of our phase imaging system was demonstrated by successful identification of breast cancer cells amongst normal cells. However, the cell identification method using this phase imaging system exhibited a false identification rate of approximately 7%. In this study, we implemented a polarimetric imaging system by introducing a polarimetric module to one arm of the Mach-Zehnder interferometer of our conventional phase imaging system. This module was comprised of a quarter wave plate and a rotational polarizer on the illumination side of the sample, and a linear polarizer on the optical detector side. In addition, we developed correction methods for the measurement errors of the optical path length and birefringence phase differences that arose through the influence of elements other than cells, such as the Petri dish. As the Petri dish holding the fluid specimens was transparent, it did not affect the amplitude information; however, the optical path length and birefringence phase differences were affected. Therefore, we proposed correction of the optical path length and birefringence phase for the influence of elements other than cells, as a prerequisite for obtaining highly precise phase and polarimetric images.

Estimation of Energy Expenditure during Treadmill Exercise via Thermal Imaging.

PubMed

Jensen, Martin Møller; Poulsen, Mathias Krogh; Alldieck, Thiemo; Larsen, Ryan Godsk; Gade, Rikke; Moeslund, Thomas Baltzer; Franch, Jesper

2016-12-01

Noninvasive imaging of oxygen uptake may provide a useful tool for the quantification of energy expenditure during human locomotion. A novel thermal imaging method (optical flow) was validated against indirect calorimetry for the estimation of energy expenditure during human walking and running. Fourteen endurance-trained subjects completed a discontinuous incremental exercise test on a treadmill. Subjects performed 4-min intervals at 3, 5, and 7 km·h (walking) and at 8, 10, 12, 14, 16, and 18 km·h (running) with 30 s of rest between intervals. Heart rate, gas exchange, and mean accelerations of ankle, thigh, wrist, and hip were measured throughout the exercise test. A thermal camera (30 frames per second) was used to quantify optical flow, calculated as the movements of the limbs relative to the trunk (internal mechanical work) and vertical movement of the trunk (external vertical mechanical work). Heart rate, gross oxygen uptake (mL·kg·min) together with gross and net energy expenditure (J·kg·min) rose with increasing treadmill velocities, as did optical flow measurements and mean accelerations (g) of ankle, thigh, wrist, and hip. Oxygen uptake was linearly correlated with optical flow across all exercise intensities (R = 0.96, P < 0.0001; V˙O2 [mL·kg·min] = 7.35 + 9.85 × optical flow [arbitrary units]). Only 3-4 s of camera recording was required to estimate an optical flow value at each velocity. Optical flow measurements provide an accurate estimation of energy expenditure during horizontal walking and running. The technique offers a novel experimental method of estimating energy expenditure during human locomotion, without use of interfering equipment attached to the subject.

A trifurcated fiber-optic-probe-based optical system designed for AGEs measurement

NASA Astrophysics Data System (ADS)

Wang, Yikun; Zhang, Long; Zhu, Ling; Liu, Yong; Zhang, Gong; Wang, An

2012-03-01

Advanced Glycation End-products (AGEs) are biochemical end-products of non-enzymatic glycation and are formed irreversibly in human serum and skin tissue. AGEs are thought to play an important role in the pathogenesis of diabetes and corresponding complications. All conventional methods for measuring AGEs must take sampling and measure in vitro. These methods are invasive and have the problem of relatively time-consuming. AGEs have fluorescent characteristics. Skin AGEs can be assessed noninvasively by collecting the fluorescence emitted from skin tissue when excited with proper light. However, skin tissue has absorption and scattering effects on fluorescence of AGEs, it is not reliable to evaluate the accumulation of AGEs according the emitted fluorescence but not considering optical properties of skin tissue. In this study, a portable system for detecting AGEs fluorescence and skin reflectance spectrum simultaneously has been developed. The system mainly consists of an ultraviolet light source, a broadband light source, a trifurcated fiber-optic probe, and a compact charge coupled device (CCD) spectrometer. The fiber-optic probe consists of 36 optical fibers which are connected to the ultraviolet light source, 6 optical fibers connected to the broadband light source, and a core fiber connected to the CCD spectrometer. Demonstrative test measurements with the system on skin tissue of 40 healthy subjects have been performed. Using parameters that are calculated from skin reflectance spectrum, the distortion effects caused by skin absorption and scattering can be eliminated, and the integral intensity of corrected fluorescence has a strong correlation with the accumulation of AGEs. The system looks very promising for both laboratory and clinical applications to monitor AGEs related diseases, especially for chronic diabetes and complications.

IMAGING WITH MULTIMODAL ADAPTIVE-OPTICS OPTICAL COHERENCE TOMOGRAPHY IN MULTIPLE EVANESCENT WHITE DOT SYNDROME: THE STRUCTURE AND FUNCTIONAL RELATIONSHIP.

PubMed

Labriola, Leanne T; Legarreta, Andrew D; Legarreta, John E; Nadler, Zach; Gallagher, Denise; Hammer, Daniel X; Ferguson, R Daniel; Iftimia, Nicusor; Wollstein, Gadi; Schuman, Joel S

2016-01-01

To elucidate the location of pathological changes in multiple evanescent white dot syndrome (MEWDS) with the use of multimodal adaptive optics (AO) imaging. A 5-year observational case study of a 24-year-old female with recurrent MEWDS. Full examination included history, Snellen chart visual acuity, pupil assessment, intraocular pressures, slit lamp evaluation, dilated fundoscopic exam, imaging with Fourier-domain optical coherence tomography (FD-OCT), blue-light fundus autofluorescence (FAF), fundus photography, fluorescein angiography, and adaptive-optics optical coherence tomography. Three distinct acute episodes of MEWDS occurred during the period of follow-up. Fourier-domain optical coherence tomography and adaptive-optics imaging showed disturbance in the photoreceptor outer segments (PR OS) in the posterior pole with each flare. The degree of disturbance at the photoreceptor level corresponded to size and extent of the visual field changes. All findings were transient with delineation of the photoreceptor recovery from the outer edges of the lesion inward. Hyperautofluorescence was seen during acute flares. Increase in choroidal thickness did occur with each active flare but resolved. Although changes in the choroid and RPE can be observed in MEWDS, Fourier-domain optical coherence tomography, and multimodal adaptive optics imaging localized the visually significant changes seen in this disease at the level of the photoreceptors. These transient retinal changes specifically occur at the level of the inner segment ellipsoid and OS/RPE line. En face optical coherence tomography imaging provides a detailed, yet noninvasive method for following the convalescence of MEWDS and provides insight into the structural and functional relationship of this transient inflammatory retinal disease.

Novel Bio, Chemical, Environmental Sensing Based on New Model of Total Internal Reflection in Turbid Media

NASA Astrophysics Data System (ADS)

Bali, Samir; Judge, Patrick; Phillip, Nathan; Boivin, Jordan; Scaffidi, Jonathan; Berberich, Jason; Bali, Lalit

2014-05-01

We have initiated a collaborative experimental research program that combines new advances in optical physics, field portable chemical analysis, and biosensing. Our goal is to discover and characterize new optical sensing methodologies in opaque, highly scattering (i.e., ``turbid'') media, and demonstrate new paradigms for optical sensing in research and industry. We have three specific objectives. First, we propose to fully characterize and validate a new model of total internal reflection (TIR) from highly turbid media thus enabling a first demonstration of non-invasive, in-situ, real-time particle sizing for the case of arbitrary scattering particle size-a holy grail in colloidal science. Second, we propose to implement a first demonstration of real-time non-invasive measurement of nanoparticle aggregation in highly turbid media. Third, we propose to use our new sensing methodology to demonstrate real-time in-situ label-free monitoring of molecular interactions and adsorption at surfaces. We gratefully acknowledge support from the American Chemical Society Petroleum Research Fund and Miami University's Interdisciplinary Roundtable Fund. We also gratefully acknowledge experimental help from the Miami University Instrumentation Laboratory.

Real-time imaging of human brain function by near-infrared spectroscopy using an adaptive general linear model

PubMed Central

Abdelnour, A. Farras; Huppert, Theodore

2009-01-01

Near-infrared spectroscopy is a non-invasive neuroimaging method which uses light to measure changes in cerebral blood oxygenation associated with brain activity. In this work, we demonstrate the ability to record and analyze images of brain activity in real-time using a 16-channel continuous wave optical NIRS system. We propose a novel real-time analysis framework using an adaptive Kalman filter and a state–space model based on a canonical general linear model of brain activity. We show that our adaptive model has the ability to estimate single-trial brain activity events as we apply this method to track and classify experimental data acquired during an alternating bilateral self-paced finger tapping task. PMID:19457389

Diagnostics of normal and cancer tissues by fiberoptic evanescent wave Fourier transform IR (FEW-FTIR) spectroscopy

NASA Astrophysics Data System (ADS)

Afanasyeva, Natalia I.

1998-06-01

Fourier Transform Infrared (FTIR) Spectroscopy using optical fibers operated in the attenuated total reflection (ATR) regime in the mid-IR region in the range 850 to 4000 cm-1 has recently found an application in the noninvasive diagnostics of tissues in vivo. The method is suitable for nondestructive, nontoxic, fast (seconds), direct measurements of the spectra of normal and pathological tissues in vitro, ex vivo, and in vivo in real time. The aim of our studies is the express testing of various tumor tissues at the early stages of their development. The method is expected to be further developed for endoscopic and biopsy applications as well as for the research of different materials.

A cell-free assay to determine the stoichiometry of plasma membrane proteins.

PubMed

Trigo, Cesar; Vivar, Juan P; Gonzalez, Carlos B; Brauchi, Sebastian

2013-04-01

Plasma membrane receptors, transporters, and ion channel molecules are often found as oligomeric structures that participate in signaling cascades essential for cell survival. Different states of protein oligomerization may play a role in functional control and allosteric regulation. Stochastic GFP-photobleaching (SGP) has emerged as an affordable and simple method to determine the stoichiometry of proteins at the plasma membrane. This non-invasive optical approach can be useful for total internal reflection of fluorescence microscopy (TIRFM), where signal-to-noise ratio is very high at the plasma membrane. Here, we report an alternative methodology implemented on a standard laser scanning confocal microscope (LSCM). The simplicity of our method will allow for its implementation in any epifluorescence microscope of choice.

Accurate and simple method for quantification of hepatic fat content using magnetic resonance imaging: a prospective study in biopsy-proven nonalcoholic fatty liver disease.

PubMed

Hatta, Tomoko; Fujinaga, Yasunari; Kadoya, Masumi; Ueda, Hitoshi; Murayama, Hiroaki; Kurozumi, Masahiro; Ueda, Kazuhiko; Komatsu, Michiharu; Nagaya, Tadanobu; Joshita, Satoru; Kodama, Ryo; Tanaka, Eiji; Uehara, Tsuyoshi; Sano, Kenji; Tanaka, Naoki

2010-12-01

To assess the degree of hepatic fat content, simple and noninvasive methods with high objectivity and reproducibility are required. Magnetic resonance imaging (MRI) is one such candidate, although its accuracy remains unclear. We aimed to validate an MRI method for quantifying hepatic fat content by calibrating MRI reading with a phantom and comparing MRI measurements in human subjects with estimates of liver fat content in liver biopsy specimens. The MRI method was performed by a combination of MRI calibration using a phantom and double-echo chemical shift gradient-echo sequence (double-echo fast low-angle shot sequence) that has been widely used on a 1.5-T scanner. Liver fat content in patients with nonalcoholic fatty liver disease (NAFLD, n = 26) was derived from a calibration curve generated by scanning the phantom. Liver fat was also estimated by optical image analysis. The correlation between the MRI measurements and liver histology findings was examined prospectively. Magnetic resonance imaging measurements showed a strong correlation with liver fat content estimated from the results of light microscopic examination (correlation coefficient 0.91, P < 0.001) regardless of the degree of hepatic steatosis. Moreover, the severity of lobular inflammation or fibrosis did not influence the MRI measurements. This MRI method is simple and noninvasive, has excellent ability to quantify hepatic fat content even in NAFLD patients with mild steatosis or advanced fibrosis, and can be performed easily without special devices.

Physics and instrumentation for imaging in-vivo drug distribution.

PubMed

Singh, M; Waluch, V

2000-03-15

Several imaging methods are currently available to measure drugs noninvasively. Of these, two techniques are today central to such measurements: nuclear imaging and magnetic resonance imaging/spectroscopy (MRI and MRS). While other methods, such as optical techniques, are rapidly gaining in interest, they have not yet attained the degree of development that makes them effective in measuring drugs in living systems, except in a small number of examples. The following introduction provides some basic elements of the potential and the limitations of both nuclear imaging and MRI/MRS techniques, methods that will be used in the studies described in the articles in this issue. However, and for those desiring to gain a better understanding of both methods, the reader is advised to consult much more extensive reviews and books describing such methods. A suggested list of books and articles on Nuclear Imaging and MRI/MRS is given.

Numerical study on trapping and guiding of nanoparticles in a flow using scattering field of laser light

NASA Astrophysics Data System (ADS)

Yokoi, Naomichi; Aizu, Yoshihisa

2018-01-01

Optical trapping and guiding using laser have been proven to be useful for non-contact and non-invasive manipulation of small objects such as biological cells, organelles within cells, and dielectric particles. We have numerically investigated so far the motion of a Brownian particle suspended in still water under the illumination of a speckle pattern generated by the interference of coherent light scattered by a rough object. In the present study, we investigate numerically the motion of a particle in a water flow under the illumination of a speckle pattern that is at rest or in motion. Trajectory of the particle is simulated in relation with its size, flow velocity, maximum irradiance, and moving velocity of the speckle pattern to confirm the feasibility of the present method for performing optical trapping and guiding of the particle in the flow.

Optical micromanipulation of nanoparticles and cells inside living zebrafish.

PubMed

Johansen, Patrick Lie; Fenaroli, Federico; Evensen, Lasse; Griffiths, Gareth; Koster, Gerbrand

2016-03-21

Regulation of biological processes is often based on physical interactions between cells and their microenvironment. To unravel how and where interactions occur, micromanipulation methods can be used that offer high-precision control over the duration, position and magnitude of interactions. However, lacking an in vivo system, micromanipulation has generally been done with cells in vitro, which may not reflect the complex in vivo situation inside multicellular organisms. Here using optical tweezers we demonstrate micromanipulation throughout the transparent zebrafish embryo. We show that different cells, as well as injected nanoparticles and bacteria can be trapped and that adhesion properties and membrane deformation of endothelium and macrophages can be analysed. This non-invasive micromanipulation inside a whole-organism gives direct insights into cell interactions that are not accessible using existing approaches. Potential applications include screening of nanoparticle-cell interactions for cancer therapy or tissue invasion studies in cancer and infection biology.

Investigating the influence of chromatic aberration and optical illumination bandwidth on fundus imaging in rats

NASA Astrophysics Data System (ADS)

Li, Hao; Liu, Wenzhong; Zhang, Hao F.

2015-10-01

Rodent models are indispensable in studying various retinal diseases. Noninvasive, high-resolution retinal imaging of rodent models is highly desired for longitudinally investigating the pathogenesis and therapeutic strategies. However, due to severe aberrations, the retinal image quality in rodents can be much worse than that in humans. We numerically and experimentally investigated the influence of chromatic aberration and optical illumination bandwidth on retinal imaging. We confirmed that the rat retinal image quality decreased with increasing illumination bandwidth. We achieved the retinal image resolution of 10 μm using a 19 nm illumination bandwidth centered at 580 nm in a home-built fundus camera. Furthermore, we observed higher chromatic aberration in albino rat eyes than in pigmented rat eyes. This study provides a design guide for high-resolution fundus camera for rodents. Our method is also beneficial to dispersion compensation in multiwavelength retinal imaging applications.

Numerical study on trapping and guiding of nanoparticles in a flow using scattering field of laser light

NASA Astrophysics Data System (ADS)

Yokoi, Naomichi; Aizu, Yoshihisa

2018-06-01

Optical trapping and guiding using laser have been proven to be useful for non-contact and non-invasive manipulation of small objects such as biological cells, organelles within cells, and dielectric particles. We have numerically investigated so far the motion of a Brownian particle suspended in still water under the illumination of a speckle pattern generated by the interference of coherent light scattered by a rough object. In the present study, we investigate numerically the motion of a particle in a water flow under the illumination of a speckle pattern that is at rest or in motion. Trajectory of the particle is simulated in relation with its size, flow velocity, maximum irradiance, and moving velocity of the speckle pattern to confirm the feasibility of the present method for performing optical trapping and guiding of the particle in the flow.

High resolution coherence domain depth-resolved nailfold capillaroscopy based on correlation mapping optical coherence tomography

NASA Astrophysics Data System (ADS)

Subhash, Hrebesh M.; O'Gorman, Sean; Neuhaus, Kai; Leahy, Martin

2014-03-01

In this paper we demonstrate a novel application of correlation mapping optical coherence tomography (cm-OCT) for volumetric nailfold capillaroscopy (NFC). NFC is a widely used non-invasive diagnostic method to analyze capillary morphology and microvascular abnormalities of nailfold area for a range of disease conditions. However, the conventional NFC is incapable of providing volumetric imaging, when volumetric quantitative microangiopathic parameters such as plexus morphology, capillary density, and morphologic anomalies of the end row loops most critical. cm-OCT is a recently developed well established coherence domain magnitude based angiographic modality, which takes advantage of the time-varying speckle effect, which is normally dominant in the vicinity of vascular regions compared to static tissue region. It utilizes the correlation coefficient as a direct measurement of decorrelation between two adjacent B-frames to enhance the visibility of depth-resolved microcirculation.

New non-invasive safe, quick, economical method of detecting various cancers was found using QRS complex or rising part of T-wave of recorded ECGs. Cancers can be screened along with their biochemical parameters & therapeutic effects of any cancer treatments can be evaluated using recorded ECGs of the same individual.

PubMed

Omura, Yoshiaki; Lu, Dominic; O'Young, Brian; Jones, Marilyn; Nihrane, Abdallah; Duvvi, Harsha; Shimotsuura, Yasuhiro; Ohki, Motomu

2015-01-01

There are many methods of detecting cancers including detection of cancer markers by blood test, (which is invasive, time consuming and relatively expensive), detection of cancers by non-invasive methods such as X-Ray, CT scan, and MRI & PET Scan (which are non-invasive and quick but very expensive). Our research was performed to develop new non-invasive, safe, quick economical method of detecting cancers and the 1st author already developed for clinically important non-invasive new methods including early stage of present method using his method of localizing accurate organ representation areas of face, eyebrows, upper lip, lower lip, surface and dorsal part of the tongue, surface backs, and palm side of the hands. This accurate localization of the organ representation area of the different parts of the body was performed using electromagnetic field resonance phenomenon between 2 identical molecules or tissues based on our US patented non-invasive method in 1993. Since year 2000, we developed the following non-invasive diagnostic methods that can be quickly identified by the patented simple non-invasive method without using expensive or bulky instrument at any office or field where there is no electricity or instrument available. The following are examples of non-invasive quick method of diagnosis and treatment of cancers using different approaches: 1) Soft red laser beam scanning of different parts of body; 2) By speaking voice; 3) Visible and invisible characteristic abnormalities on different organ representation areas of the different parts of the body, and 4) Mouth, Hand, and Foot Writings of both right and left side of the body. As a consequence of our latest research, we were able to develop a simple method of detecting cancer from existing recorded electrocardiograms. In this article, we are going to describe the method and result of clinical applications on many different cancers of different organs including lung, esophagus, breast, stomach, colon, uterus, ovary, prostate gland, as well as common bone marrow related malignancies such as Hodgkin's Lymphoma, Non-Hodgkin's Lymphoma, Multiple Myeloma as well as Leukemia.

Dynamic-focusing microscope objective for optical coherence tomography

NASA Astrophysics Data System (ADS)

Murali, Supraja; Rolland, Jannick

2007-01-01

Optical Coherence Tomography (OCT) is a novel optical imaging technique that has assumed significant importance in bio-medical imaging in the last two decades because it is non-invasive and provides accurate, high resolution images of three dimensional cross-sections of body tissue, exceeding the capabilities of the current predominant imaging technique - ultrasound. In this paper, the application of high resolution OCT, known as optical coherence microscopy (OCM) is investigated for in vivo detection of abnormal skin pathology for the early diagnosis of cancer. A main challenge in OCM is maintaining invariant resolution throughout the sample. The technology presented is based on a dynamic focusing microscope imaging probe conceived for skin imaging and the detection of abnormalities in the epithelium. A novel method for dynamic focusing in the biological sample is presented using variable-focus lens technology to obtain three dimensional images with invariant resolution throughout the cross-section and depth of the sample is presented and discussed. A low coherence broadband source centered at near IR wavelengths is used to illuminate the sample. The design, analysis and predicted performance of the dynamic focusing microscope objective designed for dynamic three dimensional imaging at 5μm resolution for the chosen broadband spectrum is presented.

Parallel mapping of optical near-field interactions by molecular motor-driven quantum dots.

PubMed

Groß, Heiko; Heil, Hannah S; Ehrig, Jens; Schwarz, Friedrich W; Hecht, Bert; Diez, Stefan

2018-04-30

In the vicinity of metallic nanostructures, absorption and emission rates of optical emitters can be modulated by several orders of magnitude 1,2 . Control of such near-field light-matter interaction is essential for applications in biosensing 3 , light harvesting 4 and quantum communication 5,6 and requires precise mapping of optical near-field interactions, for which single-emitter probes are promising candidates 7-11 . However, currently available techniques are limited in terms of throughput, resolution and/or non-invasiveness. Here, we present an approach for the parallel mapping of optical near-field interactions with a resolution of <5 nm using surface-bound motor proteins to transport microtubules carrying single emitters (quantum dots). The deterministic motion of the quantum dots allows for the interpolation of their tracked positions, resulting in an increased spatial resolution and a suppression of localization artefacts. We apply this method to map the near-field distribution of nanoslits engraved into gold layers and find an excellent agreement with finite-difference time-domain simulations. Our technique can be readily applied to a variety of surfaces for scalable, nanometre-resolved and artefact-free near-field mapping using conventional wide-field microscopes.

Ocular static and dynamic light scattering: a noninvasive diagnostic tool for eye research and clinical practice

NASA Technical Reports Server (NTRS)

Ansari, Rafat R.

2004-01-01

The noninvasive techniques of static and dynamic light scattering are emerging as valuable diagnostic tools for the early detection of ocular and systemic diseases. These include corneal abnormalities, pigmentary dispersion syndrome, glaucoma, cataract, diabetic vitreopathy, and possibly macular degeneration. Systemic conditions such as diabetes and possibly Alzheimer's disease can potentially be detected early via ocular tissues. The current state of development of these techniques for application to ophthalmic research and ultimately clinical practice is reviewed. (c) 2004 Society of Photo-Optical Instrumentation Engineers.

The fundus photo has met its match: optical coherence tomography and adaptive optics ophthalmoscopy are here to stay

PubMed Central

Morgan, Jessica I. W.

2016-01-01

Purpose Over the past 25 years, optical coherence tomography (OCT) and adaptive optics (AO) ophthalmoscopy have revolutionised our ability to non-invasively observe the living retina. The purpose of this review is to highlight the techniques and human clinical applications of recent advances in OCT and adaptive optics scanning laser/light ophthalmoscopy (AOSLO) ophthalmic imaging. Recent findings Optical coherence tomography retinal and optic nerve head (ONH) imaging technology allows high resolution in the axial direction resulting in cross-sectional visualisation of retinal and ONH lamination. Complementary AO ophthalmoscopy gives high resolution in the transverse direction resulting in en face visualisation of retinal cell mosaics. Innovative detection schemes applied to OCT and AOSLO technologies (such as spectral domain OCT, OCT angiography, confocal and non-confocal AOSLO, fluorescence, and AO-OCT) have enabled high contrast between retinal and ONH structures in three dimensions and have allowed in vivo retinal imaging to approach that of histological quality. In addition, both OCT and AOSLO have shown the capability to detect retinal reflectance changes in response to visual stimuli, paving the way for future studies to investigate objective biomarkers of visual function at the cellular level. Increasingly, these imaging techniques are being applied to clinical studies of the normal and diseased visual system. Summary Optical coherence tomography and AOSLO technologies are capable of elucidating the structure and function of the retina and ONH noninvasively with unprecedented resolution and contrast. The techniques have proven their worth in both basic science and clinical applications and each will continue to be utilised in future studies for many years to come. PMID:27112222

Portable, Fiber-Based, Diffuse Reflection Spectroscopy (DRS) Systems for Estimating Tissue Optical Properties.

PubMed

Vishwanath, Karthik; Chang, Kevin; Klein, Daniel; Deng, Yu Feng; Chang, Vivide; Phelps, Janelle E; Ramanujam, Nimmi

2011-02-01

Steady-state diffuse reflection spectroscopy is a well-studied optical technique that can provide a noninvasive and quantitative method for characterizing the absorption and scattering properties of biological tissues. Here, we compare three fiber-based diffuse reflection spectroscopy systems that were assembled to create a light-weight, portable, and robust optical spectrometer that could be easily translated for repeated and reliable use in mobile settings. The three systems were built using a broadband light source and a compact, commercially available spectrograph. We tested two different light sources and two spectrographs (manufactured by two different vendors). The assembled systems were characterized by their signal-to-noise ratios, the source-intensity drifts, and detector linearity. We quantified the performance of these instruments in extracting optical properties from diffuse reflectance spectra in tissue-mimicking liquid phantoms with well-controlled optical absorption and scattering coefficients. We show that all assembled systems were able to extract the optical absorption and scattering properties with errors less than 10%, while providing greater than ten-fold decrease in footprint and cost (relative to a previously well-characterized and widely used commercial system). Finally, we demonstrate the use of these small systems to measure optical biomarkers in vivo in a small-animal model cancer therapy study. We show that optical measurements from the simple portable system provide estimates of tumor oxygen saturation similar to those detected using the commercial system in murine tumor models of head and neck cancer.

Diffusion fMRI detects white-matter dysfunction in mice with acute optic neuritis

PubMed Central

Lin, Tsen-Hsuan; Spees, William M.; Chiang, Chia-Wen; Trinkaus, Kathryn; Cross, Anne H.; Song, Sheng-Kwei

2014-01-01

Optic neuritis is a frequent and early symptom of multiple sclerosis (MS). Conventional magnetic resonance (MR) techniques provide means to assess multiple MS-related pathologies, including axonal injury, demyelination, and inflammation. A method to directly and non-invasively probe white-matter function could further elucidate the interplay of underlying pathologies and functional impairments. Previously, we demonstrated a significant 27% activation-associated decrease in the apparent diffusion coefficient of water perpendicular to the axonal fibers (ADC⊥) in normal C57BL/6 mouse optic nerve with visual stimulation using diffusion fMRI. Here we apply this approach to explore the relationship between visual acuity, optic nerve pathology, and diffusion fMRI in the experimental autoimmune encephalomyelitis (EAE) mouse model of optic neuritis. Visual stimulation produced a significant 25% (vs. baseline) ADC⊥ decrease in sham EAE optic nerves, while only a 7% (vs. baseline) ADC⊥ decrease was seen in EAE mice with acute optic neuritis. The reduced activation-associated ADC⊥ response correlated with post-MRI immunohistochemistry determined pathologies (including inflammation, demyelination, and axonal injury). The negative correlation between activation-associated ADC⊥ response and visual acuity was also found when pooling EAE-affected and sham groups under our experimental criteria. Results suggest that reduction in diffusion fMRI directly reflects impaired axonal-activation in EAE mice with optic neuritis. Diffusion fMRI holds promise for directly gauging in vivo white-matter dysfunction or therapeutic responses in MS patients. PMID:24632420

In situ Biofilm Quantification in Bioelectrochemical Systems by using Optical Coherence Tomography.

PubMed

Molenaar, Sam D; Sleutels, Tom; Pereira, Joao; Iorio, Matteo; Borsje, Casper; Zamudio, Julian A; Fabregat-Santiago, Francisco; Buisman, Cees J N; Ter Heijne, Annemiek

2018-04-25

Detailed studies of microbial growth in bioelectrochemical systems (BESs) are required for their suitable design and operation. Here, we report the use of optical coherence tomography (OCT) as a tool for in situ and noninvasive quantification of biofilm growth on electrodes (bioanodes). An experimental platform is designed and described in which transparent electrodes are used to allow real-time, 3D biofilm imaging. The accuracy and precision of the developed method is assessed by relating the OCT results to well-established standards for biofilm quantification (chemical oxygen demand (COD) and total N content) and show high correspondence to these standards. Biofilm thickness observed by OCT ranged between 3 and 90 μm for experimental durations ranging from 1 to 24 days. This translated to growth yields between 38 and 42 mgCODbiomass  gCODacetate -1 at an anode potential of -0.35 V versus Ag/AgCl. Time-lapse observations of an experimental run performed in duplicate show high reproducibility in obtained microbial growth yield by the developed method. As such, we identify OCT as a powerful tool for conducting in-depth characterizations of microbial growth dynamics in BESs. Additionally, the presented platform allows concomitant application of this method with various optical and electrochemical techniques. © 2018 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Techniques of noninvasive optical tomographic imaging

NASA Astrophysics Data System (ADS)

Rosen, Joseph; Abookasis, David; Gokhler, Mark

2006-01-01

Recently invented methods of optical tomographic imaging through scattering and absorbing media are presented. In one method, the three-dimensional structure of an object hidden between two biological tissues is recovered from many noisy speckle pictures obtained on the output of a multi-channeled optical imaging system. Objects are recovered from many speckled images observed by a digital camera through two stereoscopic microlens arrays. Each microlens in each array generates a speckle image of the object buried between the layers. In the computer each image is Fourier transformed jointly with an image of the speckled point-like source captured under the same conditions. A set of the squared magnitudes of the Fourier-transformed pictures is accumulated to form a single average picture. This final picture is again Fourier transformed, resulting in the three-dimensional reconstruction of the hidden object. In the other method, the effect of spatial longitudinal coherence is used for imaging through an absorbing layer with different thickness, or different index of refraction, along the layer. The technique is based on synthesis of multiple peak spatial degree of coherence. This degree of coherence enables us to scan simultaneously different sample points on different altitudes, and thus decreases the acquisition time. The same multi peak degree of coherence is also used for imaging through the absorbing layer. Our entire experiments are performed with a quasi-monochromatic light source. Therefore problems of dispersion and inhomogeneous absorption are avoided.

Optical magnetic detection of single-neuron action potentials using quantum defects in diamond

PubMed Central

Barry, John F.; Turner, Matthew J.; Schloss, Jennifer M.; Glenn, David R.; Song, Yuyu; Lukin, Mikhail D.; Park, Hongkun; Walsworth, Ronald L.

2016-01-01

Magnetic fields from neuronal action potentials (APs) pass largely unperturbed through biological tissue, allowing magnetic measurements of AP dynamics to be performed extracellularly or even outside intact organisms. To date, however, magnetic techniques for sensing neuronal activity have either operated at the macroscale with coarse spatial and/or temporal resolution—e.g., magnetic resonance imaging methods and magnetoencephalography—or been restricted to biophysics studies of excised neurons probed with cryogenic or bulky detectors that do not provide single-neuron spatial resolution and are not scalable to functional networks or intact organisms. Here, we show that AP magnetic sensing can be realized with both single-neuron sensitivity and intact organism applicability using optically probed nitrogen-vacancy (NV) quantum defects in diamond, operated under ambient conditions and with the NV diamond sensor in close proximity (∼10 µm) to the biological sample. We demonstrate this method for excised single neurons from marine worm and squid, and then exterior to intact, optically opaque marine worms for extended periods and with no observed adverse effect on the animal. NV diamond magnetometry is noninvasive and label-free and does not cause photodamage. The method provides precise measurement of AP waveforms from individual neurons, as well as magnetic field correlates of the AP conduction velocity, and directly determines the AP propagation direction through the inherent sensitivity of NVs to the associated AP magnetic field vector. PMID:27911765

Optical magnetic detection of single-neuron action potentials using quantum defects in diamond.

PubMed

Barry, John F; Turner, Matthew J; Schloss, Jennifer M; Glenn, David R; Song, Yuyu; Lukin, Mikhail D; Park, Hongkun; Walsworth, Ronald L

2016-12-06

Magnetic fields from neuronal action potentials (APs) pass largely unperturbed through biological tissue, allowing magnetic measurements of AP dynamics to be performed extracellularly or even outside intact organisms. To date, however, magnetic techniques for sensing neuronal activity have either operated at the macroscale with coarse spatial and/or temporal resolution-e.g., magnetic resonance imaging methods and magnetoencephalography-or been restricted to biophysics studies of excised neurons probed with cryogenic or bulky detectors that do not provide single-neuron spatial resolution and are not scalable to functional networks or intact organisms. Here, we show that AP magnetic sensing can be realized with both single-neuron sensitivity and intact organism applicability using optically probed nitrogen-vacancy (NV) quantum defects in diamond, operated under ambient conditions and with the NV diamond sensor in close proximity (∼10 µm) to the biological sample. We demonstrate this method for excised single neurons from marine worm and squid, and then exterior to intact, optically opaque marine worms for extended periods and with no observed adverse effect on the animal. NV diamond magnetometry is noninvasive and label-free and does not cause photodamage. The method provides precise measurement of AP waveforms from individual neurons, as well as magnetic field correlates of the AP conduction velocity, and directly determines the AP propagation direction through the inherent sensitivity of NVs to the associated AP magnetic field vector.

Preoperative Mapping of Nonmelanoma Skin Cancer Using Spatial Frequency Domain and Ultrasound Imaging

PubMed Central

Rohrbach, Daniel J.; Muffoletto, Daniel; Huihui, Jonathan; Saager, Rolf; Keymel, Kenneth; Paquette, Anne; Morgan, Janet; Zeitouni, Nathalie; Sunar, Ulas

2014-01-01

Rationale and Objectives The treatment of nonmelanoma skin cancer (NMSC) is usually by surgical excision or Mohs micrographic surgery and alternatively may include photodynamic therapy (PDT). To guide surgery and to optimize PDT, information about the tumor structure, optical parameters, and vasculature is desired. Materials and Methods Spatial frequency domain imaging (SFDI) can map optical absorption, scattering, and fluorescence parameters that can enhance tumor contrast and quantify light and photosensitizer dose. High frequency ultrasound (HFUS) imaging can provide high-resolution tumor structure and depth, which is useful for both surgery and PDT planning. Results Here, we present preliminary results from our recently developed clinical instrument for patients with NMSC. We quantified optical absorption and scattering, blood oxygen saturation (StO2), and total hemoglobin concentration (THC) with SFDI and lesion thickness with ultrasound. These results were compared to histological thickness of excised tumor sections. Conclusions SFDI quantified optical parameters with high precision, and multiwavelength analysis enabled 2D mappings of tissue StO2 and THC. HFUS quantified tumor thickness that correlated well with histology. The results demonstrate the feasibility of the instrument for noninvasive mapping of optical, physiological, and ultrasound contrasts in human skin tumors for surgery guidance and therapy planning. PMID:24439339

Fast Calcium Imaging with Optical Sectioning via HiLo Microscopy.

PubMed

Lauterbach, Marcel A; Ronzitti, Emiliano; Sternberg, Jenna R; Wyart, Claire; Emiliani, Valentina

2015-01-01

Imaging intracellular calcium concentration via reporters that change their fluorescence properties upon binding of calcium, referred to as calcium imaging, has revolutionized our way to probe neuronal activity non-invasively. To reach neurons densely located deep in the tissue, optical sectioning at high rate of acquisition is necessary but difficult to achieve in a cost effective manner. Here we implement an accessible solution relying on HiLo microscopy to provide robust optical sectioning with a high frame rate in vivo. We show that large calcium signals can be recorded from dense neuronal populations at high acquisition rates. We quantify the optical sectioning capabilities and demonstrate the benefits of HiLo microscopy compared to wide-field microscopy for calcium imaging and 3D reconstruction. We apply HiLo microscopy to functional calcium imaging at 100 frames per second deep in biological tissues. This approach enables us to discriminate neuronal activity of motor neurons from different depths in the spinal cord of zebrafish embryos. We observe distinct time courses of calcium signals in somata and axons. We show that our method enables to remove large fluctuations of the background fluorescence. All together our setup can be implemented to provide efficient optical sectioning in vivo at low cost on a wide range of existing microscopes.

Repeatability and reproducibility of optic nerve head perfusion measurements using optical coherence tomography angiography

NASA Astrophysics Data System (ADS)

Chen, Chieh-Li; Bojikian, Karine D.; Xin, Chen; Wen, Joanne C.; Gupta, Divakar; Zhang, Qinqin; Mudumbai, Raghu C.; Johnstone, Murray A.; Chen, Philip P.; Wang, Ruikang K.

2016-06-01

Optical coherence tomography angiography (OCTA) has increasingly become a clinically useful technique in ophthalmic imaging. We evaluate the repeatability and reproducibility of blood perfusion in the optic nerve head (ONH) measured using optical microangiography (OMAG)-based OCTA. Ten eyes from 10 healthy volunteers are recruited and scanned three times with a 68-kHz Cirrus HD-OCT 5000-based OMAG prototype system (Carl Zeiss Meditec Inc., Dublin, California) centered at the ONH involving two separate visits within six weeks. Vascular images are generated with OMAG processing by detecting the differences in OCT signals between consecutive B-scans acquired at the same retina location. ONH perfusion is quantified as flux, vessel area density, and normalized flux within the ONH for the prelaminar, lamina cribrosa, and the full ONH. Coefficient of variation (CV) and intraclass correlation coefficient (ICC) are used to evaluate intravisit and intervisit repeatability, and interobserver reproducibility. ONH perfusion measurements show high repeatability [CV≤3.7% (intravisit) and ≤5.2% (intervisit)] and interobserver reproducibility (ICC≤0.966) in all three layers by three metrics. OCTA provides a noninvasive method to visualize and quantify ONH perfusion in human eyes with excellent repeatability and reproducibility, which may add additional insight into ONH perfusion in clinical practice.

Fast Calcium Imaging with Optical Sectioning via HiLo Microscopy

PubMed Central

Sternberg, Jenna R.; Wyart, Claire; Emiliani, Valentina

2015-01-01

Imaging intracellular calcium concentration via reporters that change their fluorescence properties upon binding of calcium, referred to as calcium imaging, has revolutionized our way to probe neuronal activity non-invasively. To reach neurons densely located deep in the tissue, optical sectioning at high rate of acquisition is necessary but difficult to achieve in a cost effective manner. Here we implement an accessible solution relying on HiLo microscopy to provide robust optical sectioning with a high frame rate in vivo. We show that large calcium signals can be recorded from dense neuronal populations at high acquisition rates. We quantify the optical sectioning capabilities and demonstrate the benefits of HiLo microscopy compared to wide-field microscopy for calcium imaging and 3D reconstruction. We apply HiLo microscopy to functional calcium imaging at 100 frames per second deep in biological tissues. This approach enables us to discriminate neuronal activity of motor neurons from different depths in the spinal cord of zebrafish embryos. We observe distinct time courses of calcium signals in somata and axons. We show that our method enables to remove large fluctuations of the background fluorescence. All together our setup can be implemented to provide efficient optical sectioning in vivo at low cost on a wide range of existing microscopes. PMID:26625116

Muscle tissue saturation in humans studied with two non-invasive optical techniques: a comparative study

NASA Astrophysics Data System (ADS)

Shaharin, Alfi; Krite Svanberg, Emilie; Ellerström, Ida; Subash, Arman Ahamed; Khoptyar, Dmitry; Andersson-Engels, Stefan; Åkeson, Jonas

2013-11-01

Muscle tissue saturation (StO2) has been measured with two non-invasive optical techniques and the results were compared. One of the techniques is widely used in the hospitals - the CW-NIRS technique. The other is the photon timeof- flight spectrometer (pTOFS) developed in the Group of Biophotonics, Lund University, Sweden. The wavelengths used in both the techniques are 730 nm and 810 nm. A campaign was arranged to perform measurements on 21 (17 were taken for comparison) healthy adult volunteers (8 women and 13 men). Oxygen saturations were measured at the right lower arm of each volunteer. To observe the effects of different provocations on the oxygen saturation a blood pressure cuff was attached in the upper right arm. For CW-NIRS, the tissue saturation values were in the range from 70-90%, while for pTOFS the values were in the range from 55-60%.

Detection of extracellular matrix modification in cancer models with inverse spectroscopic optical coherence tomography

NASA Astrophysics Data System (ADS)

Spicer, Graham L. C.; Azarin, Samira M.; Yi, Ji; Young, Scott T.; Ellis, Ronald; Bauer, Greta M.; Shea, Lonnie D.; Backman, Vadim

2016-10-01

In cancer biology, there has been a recent effort to understand tumor formation in the context of the tissue microenvironment. In particular, recent progress has explored the mechanisms behind how changes in the cell-extracellular matrix ensemble influence progression of the disease. The extensive use of in vitro tissue culture models in simulant matrix has proven effective at studying such interactions, but modalities for non-invasively quantifying aspects of these systems are scant. We present the novel application of an imaging technique, Inverse Spectroscopic Optical Coherence Tomography, for the non-destructive measurement of in vitro biological samples during matrix remodeling. Our findings indicate that the nanoscale-sensitive mass density correlation shape factor D of cancer cells increases in response to a more crosslinked matrix. We present a facile technique for the non-invasive, quantitative study of the micro- and nano-scale structure of the extracellular matrix and its host cells.

High resolution Physio-chemical Tissue Analysis: Towards Non-invasive In Vivo Biopsy

NASA Astrophysics Data System (ADS)

Xu, Guan; Meng, Zhuo-Xian; Lin, Jian-Die; Deng, Cheri X.; Carson, Paul L.; Fowlkes, J. Brian; Tao, Chao; Liu, Xiaojun; Wang, Xueding

2016-02-01

Conventional gold standard histopathologic diagnosis requires information of both high resolution structural and chemical changes in tissue. Providing optical information at ultrasonic resolution, photoacoustic (PA) technique could provide highly sensitive and highly accurate tissue characterization noninvasively in the authentic in vivo environment, offering a replacement for histopathology. A two-dimensional (2D) physio-chemical spectrogram (PCS) combining micrometer to centimeter morphology and chemical composition simultaneously can be generated for each biological sample with PA measurements at multiple optical wavelengths. This spectrogram presents a unique 2D “physio-chemical signature” for any specific type of tissue. Comprehensive analysis of PCS, termed PA physio-chemical analysis (PAPCA), can lead to very rich diagnostic information, including the contents of all relevant molecular and chemical components along with their corresponding histological microfeatures, comparable to those accessible by conventional histology. PAPCA could contribute to the diagnosis of many diseases involving diffusive patterns such as fatty liver.

Automated segmentation algorithm for detection of changes in vaginal epithelial morphology using optical coherence tomography

NASA Astrophysics Data System (ADS)

Chitchian, Shahab; Vincent, Kathleen L.; Vargas, Gracie; Motamedi, Massoud

2012-11-01

We have explored the use of optical coherence tomography (OCT) as a noninvasive tool for assessing the toxicity of topical microbicides, products used to prevent HIV, by monitoring the integrity of the vaginal epithelium. A novel feature-based segmentation algorithm using a nearest-neighbor classifier was developed to monitor changes in the morphology of vaginal epithelium. The two-step automated algorithm yielded OCT images with a clearly defined epithelial layer, enabling differentiation of normal and damaged tissue. The algorithm was robust in that it was able to discriminate the epithelial layer from underlying stroma as well as residual microbicide product on the surface. This segmentation technique for OCT images has the potential to be readily adaptable to the clinical setting for noninvasively defining the boundaries of the epithelium, enabling quantifiable assessment of microbicide-induced damage in vaginal tissue.

Optical Spectroscopy for Noninvasive Monitoring of Stem Cell Differentiation

PubMed Central

Downes, Andrew; Mouras, Rabah; Elfick, Alistair

2010-01-01

There is a requirement for a noninvasive technique to monitor stem cell differentiation. Several candidates based on optical spectroscopy are discussed in this review: Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and coherent anti-Stokes Raman scattering (CARS) microscopy. These techniques are briefly described, and the ability of each to distinguish undifferentiated from differentiated cells is discussed. FTIR spectroscopy has demonstrated its ability to distinguish between stem cells and their derivatives. Raman spectroscopy shows a clear reduction in DNA and RNA concentrations during embryonic stem cell differentiation (agreeing with the well-known reduction in the nucleus to cytoplasm ratio) and also shows clear increases in mineral content during differentiation of mesenchymal stem cells. CARS microscopy can map these DNA, RNA, and mineral concentrations at high speed, and Mutliplex CARS spectroscopy/microscopy is highlighted as the technique with most promise for future applications. PMID:20182537

Design of a Mechanical-Tunable Filter Spectrometer for Noninvasive Glucose Measurement

NASA Astrophysics Data System (ADS)

Saptari, Vidi; Youcef-Toumi, Kamal

2004-05-01

The development of an accurate and reliable noninvasive near-infrared (NIR) glucose sensor hinges on the success in addressing the sensitivity and the specificity problems associated with the weak glucose signals and the overlapping NIR spectra. Spectroscopic hardware parameters most relevant to noninvasive blood glucose measurement are discussed, which include the optical throughput, integration time, spectral range, and the spectral resolution. We propose a unique spectroscopic system using a continuously rotating interference filter, which produces a signal-to-noise ratio of the order of 10^5 and is estimated to be the minimum required for successful in vivo glucose sensing. Using a classical least-squares algorithm and a spectral range between 2180 and 2312 nm, we extracted clinically relevant glucose concentrations in multicomponent solutions containing bovine serum albumin, triacetin, lactate, and urea.

Noninvasive Raman spectroscopy of rat tibiae: approach to in vivo assessment of bone quality

PubMed Central

Okagbare, Paul I.; Begun, Dana; Tecklenburg, Mary; Awonusi, Ayorinde; Goldstein, Steven A.

2012-01-01

Abstract. We report on in vivo noninvasive Raman spectroscopy of rat tibiae using robust fiber-optic Raman probes and holders designed for transcutaneous Raman measurements in small animals. The configuration allows placement of multiple fibers around a rat leg, maintaining contact with the skin. Bone Raman data are presented for three regions of the rat tibia diaphysis with different thicknesses of overlying soft tissue. The ability to perform in vivo noninvasive Raman measurement and evaluation of subtle changes in bone composition is demonstrated with rat leg phantoms in which the tibia has carbonated hydroxylapatite, with different carbonate contents. Our data provide proof of the principle that small changes in bone composition can be monitored through soft tissue at anatomical sites of interest in biomedical studies. PMID:23085899

Noninvasive Raman spectroscopy of rat tibiae: approach to in vivo assessment of bone quality.

PubMed

Okagbare, Paul I; Begun, Dana; Tecklenburg, Mary; Awonusi, Ayorinde; Goldstein, Steven A; Morris, Michael D

2012-09-01

We report on in vivo noninvasive Raman spectroscopy of rat tibiae using robust fiber-optic Raman probes and holders designed for transcutaneous Raman measurements in small animals. The configuration allows placement of multiple fibers around a rat leg, maintaining contact with the skin. Bone Raman data are presented for three regions of the rat tibia diaphysis with different thicknesses of overlying soft tissue. The ability to perform in vivo noninvasive Raman measurement and evaluation of subtle changes in bone composition is demonstrated with rat leg phantoms in which the tibia has carbonated hydroxylapatite, with different carbonate contents. Our data provide proof of the principle that small changes in bone composition can be monitored through soft tissue at anatomical sites of interest in biomedical studies.

Assessment of imaging parameters correlated with the effects of cryopreservation on embryo development

NASA Astrophysics Data System (ADS)

Zarnescu, Livia; Abeyta, Mike; Baer, Thomas M.; Behr, Barry; Ellerbee, Audrey K.

2014-03-01

Embryo cryopreservation is an increasingly common technique that allows patients to undergo multiple cycles of in vitro fertilization (IVF) without being subjected to repeated ovarian stimulation and oocyte retrieval. There are two types of cryopreservation commonly used in IVF clinics today: slow freezing and vitrification. Because vitrification has been shown to result in higher rates of embryo survival post-thaw compared to slow freezing, it is rapidly gaining popularity in clinics worldwide. However, several studies have shown that vitrification can still cause damage to embryos in the form of DNA fragmentation, altered mitochondrial distribution and changes in transcriptional activity, all of which are impossible to assess noninvasively. In this paper we demonstrate a new method of quantitatively and noninvasively assessing changes in embryo appearance due to vitrification. Using full-field optical coherence tomography (FF-OCT), we show that vitrification causes striking changes in the appearance of the cytoplasm that are not visible under conventional brightfield microscopy. Using an automated algorithm that extracts parameters to describe these changes, we show that these parameters can also predict viability in embryos that have undergone vitrification. An automated, noninvasive assessment of embryo viability after vitrification and thawing could have significant clinical impact: allowing clinicians to more accurately choose the most viable embryos to transfer back to patients could reduce the average number of IVF cycles that patients must undergo to achieve pregnancy.

Imaging Single Cells in the Living Retina

PubMed Central

Williams, David R.

2011-01-01

A quarter century ago, we were limited to a macroscopic view of the retina inside the living eye. Since then, new imaging technologies, including confocal scanning laser ophthalmoscopy, optical coherence tomography, and adaptive optics fundus imaging, transformed the eye into a microscope in which individual cells can now be resolved noninvasively. These technologies have enabled a wide range of studies of the retina that were previously impossible. PMID:21596053

Circumventing Therapeutic Resistance and the Emergence of Disseminated Breast Cancer Cells Through Non-Invasive Optical Imaging

DTIC Science & Technology

2015-06-01

NOTES 14. ABSTRACT Herein we explore a series of optically distinct near infrared emissive polymersomes (NIREPs; biodegradable polymer vesicles that...characterized into subtypes, without the need for a biopsy. Our system uses non-toxic, biodegradable nanoparticles (called “NIREPs”), which when injected...natural photosynthesis, which exploits NIR-absorbing dyes such as chlorophylls and pheophytins [11]. Relative to the tremendous attention that has

Optical imaging of cell death in traumatic brain injury using a heat shock protein-90 alkylator

PubMed Central

Xie, B-W; Park, D; Van Beek, E R; Blankevoort, V; Orabi, Y; Que, I; Kaijzel, E L; Chan, A; Hogg, P J; Löwik, C W G M

2013-01-01

Traumatic brain injury is a major public health concern and is characterised by both apoptotic and necrotic cell death in the lesion. Anatomical imaging is usually used to assess traumatic brain injuries and there is a need for imaging modalities that provide complementary cellular information. We sought to non-invasively image cell death in a mouse model of traumatic brain injury using a near-infrared fluorescent conjugate of a synthetic heat shock protein-90 alkylator, 4-(N-(S-glutathionylacetyl) amino) phenylarsonous acid (GSAO). GSAO labels both apoptotic and necrotic cells coincident with loss of plasma membrane integrity. The optical GSAO specifically labelled apoptotic and necrotic cells in culture and did not accumulate in healthy organs or tissues in the living mouse body. The conjugate is a very effective imager of cell death in brain lesions. The optical GSAO was detected by fluorescence intensity and GSAO bound to dying/dead cells was detected from prolongation of the fluorescence lifetime. An optimal signal-to-background ratio was achieved as early as 3 h after injection of the probe and the signal intensity positively correlated with both lesion size and probe concentration. This optical GSAO offers a convenient and robust means to non-invasively image apoptotic and necrotic cell death in brain and other lesions. PMID:23348587

Noninvasive detection of cardiovascular pulsations by optical Doppler techniques

NASA Astrophysics Data System (ADS)

Hong, HyunDae; Fox, Martin D.

1997-10-01

A system has been developed based on the measurement of skin surface vibration that can be used to detect the underlying vascular wall motion of superficial arteries and the chest wall. Data obtained from tissue phantoms suggested that the detected signals were related to intravascular pressure, an important clinical and physiological parameter. Unlike the conventional optical Doppler techniques that have been used to measure blood perfusion in skin layers and blood flow within superficial arteries, the present system was optimized to pick up skin vibrations. An optical interferometer with a 633-nm He:Ne laser was utilized to detect micrometer displacements of the skin surface. Motion velocity profiles of the skin surface near each superficial artery and auscultation points on a chest for the two heart valve sounds exhibited distinctive profiles. The theoretical and experimental results demonstrated that the system detected the velocity of skin movement, which is related to the time derivative of the pressure. The system also reduces the loading effect on the pulsation signals and heart sounds produced by the conventional piezoelectric vibration sensors. The system's sensitivity, which could be optimized further, was 366.2 micrometers /s for the present research. Overall, optical cardiovascular vibrometry has the potential to become a simple noninvasive approach to cardiovascular screening.

Oxygen Measurements in Liposome Encapsulated Hemoglobin

NASA Astrophysics Data System (ADS)

Phiri, Joshua Benjamin

Liposome encapsulated hemoglobins (LEH's) are of current interest as blood substitutes. An analytical methodology for rapid non-invasive measurements of oxygen in artificial oxygen carriers is examined. High resolution optical absorption spectra are calculated by means of a one dimensional diffusion approximation. The encapsulated hemoglobin is prepared from fresh defibrinated bovine blood. Liposomes are prepared from hydrogenated soy phosphatidylcholine (HSPC), cholesterol and dicetylphosphate using a bath sonication method. An integrating sphere spectrophotometer is employed for diffuse optics measurements. Data is collected using an automated data acquisition system employing lock-in -amplifiers. The concentrations of hemoglobin derivatives are evaluated from the corresponding extinction coefficients using a numerical technique of singular value decomposition, and verification of the results is done using Monte Carlo simulations. In situ measurements are required for the determination of hemoglobin derivatives because most encapsulation methods invariably lead to the formation of methemoglobin, a nonfunctional form of hemoglobin. The methods employed in this work lead to high resolution absorption spectra of oxyhemoglobin and other derivatives in red blood cells and liposome encapsulated hemoglobin (LEH). The analysis using singular value decomposition method offers a quantitative means of calculating the fractions of oxyhemoglobin and other hemoglobin derivatives in LEH samples. The analytical methods developed in this work will become even more useful when production of LEH as a blood substitute is scaled up to large volumes.

All-fiber variable optical delay line for applications in optical coherence tomography: feasibility study for a novel delay line.

PubMed

Choi, Eunseo; Na, Jihoon; Ryu, Seon; Mudhana, Gopinath; Lee, Byeong

2005-02-21

We have implemented an all-fiber optical delay line using two linearly chirped fiber Bragg gratings cascaded in reverse order and all-fiber optics components. The features of the proposed all-fiber based technique for variable delay line are discussed theoretically and demonstrated experimentally. The non-invasive cross-sectional images of biomedical samples as well as a transparent glass plate obtained with implemented all-fiber delay line having the axial resolution of 100 mum and the dynamic range of 50dB are presented to validates the imaging performance and demonstrate the feasibility of the delay line for optical coherence tomography.

4Pi Microscopy.

PubMed

Schmidt, Roman; Engelhardt, Johann; Lang, Marion

2013-01-01

Optical microscopy has become a key technology in the life sciences today. Its noninvasive nature provides access to the interior of intact and even living cells, where specific molecules can be precisely localized by fluorescent tagging. However, the attainable 3D resolution of an optical microscope has long been hampered by a comparatively poor resolution along the optic axis. By coherent focusing through two objective lenses, 4Pi microscopy improves the axial resolution by three- to fivefold. This primer is intended as a starting point for the design and operation of a 4Pi microscope of type A.

Microfabricated optically pumped magnetometer arrays for biomedical imaging

NASA Astrophysics Data System (ADS)

Perry, A. R.; Sheng, D.; Krzyzewski, S. P.; Geller, S.; Knappe, S.

2017-02-01

Optically-pumped magnetometers have demonstrated magnetic field measurements as precise as the best superconducting quantum interference device magnetometers. Our group develops miniature alkali atom-based magnetic sensors using microfabrication technology. Our sensors do not require cryogenic cooling, and can be positioned very close to the sample, making these sensors an attractive option for development in the medical community. We will present our latest chip-scale optically-pumped gradiometer developed for array applications to image magnetic fields from the brain noninvasively. These developments should lead to improved spatial resolution, and potentially sensitive measurements in unshielded environments.

Accuracy of continuous noninvasive arterial pressure monitoring in living-liver donors during transplantation.

PubMed

Araz, Coskun; Zeyneloglu, Pinar; Pirat, Arash; Veziroglu, Nukhet; Camkiran Firat, Aynur; Arslan, Gulnaz

2015-04-01

Hemodynamic monitoring is vital during liver transplant surgeries because distinct hemodynamic changes are expected. The continuous noninvasive arterial pressure (CNAP) monitor is a noninvasive device for continuous arterial pressure measurement by a tonometric method. This study compared continuous noninvasive arterial pressure monitoring with invasive direct arterial pressure monitoring in living-liver donors during transplant. There were 40 patients analyzed while undergoing hepatic lobectomy for liver transplant. Invasive pressure monitoring was established at the radial artery and continuous noninvasive arterial pressure monitoring using a finger sensor was recorded simultaneously from the contralateral arm. Systolic, diastolic, and mean arterial pressures from the 2 methods were compared. Correlation between the 2 methods was calculated. A total of 5433 simultaneous measurements were obtained. For systolic arterial blood pressure, 55% continuous noninvasive arterial pressure measurements were within 10% direct arterial measurement; the correlation was 0.479, continuous noninvasive arterial pressure bias was -0.3 mm Hg, and limits of agreement were 32.0 mm Hg. For diastolic arterial blood pressure, 50% continuous noninvasive arterial pressure measurements were within 10% direct arterial measurement; the correlation was 0.630, continuous noninvasive arterial pressure bias was -0.4 mm Hg, and limits of agreement were 21.1 mm Hg. For mean arterial blood pressure, 60% continuous noninvasive arterial pressure measurements were within 10% direct arterial measurement; the correlation was 0.692, continuous noninvasive arterial pressure bias was +0.4 mm Hg, and limits of agreement were 20.8 mm Hg. The 2 monitoring techniques did not show acceptable agreement. Our results suggest that continuous noninvasive arterial pressure monitoring is not equivalent to invasive arterial pressure monitoring in donors during living-donor liver transplant.

An improved thin film approximation to accurately determine the optical conductivity of graphene from infrared transmittance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weber, J. W.; Bol, A. A.; Sanden, M. C. M. van de

2014-07-07

This work presents an improved thin film approximation to extract the optical conductivity from infrared transmittance in a simple yet accurate way. This approximation takes into account the incoherent reflections from the backside of the substrate. These reflections are shown to have a significant effect on the extracted optical conductivity and hence on derived parameters as carrier mobility and density. By excluding the backside reflections, the error for these parameters for typical chemical vapor deposited (CVD) graphene on a silicon substrate can be as high as 17% and 45% for the carrier mobility and density, respectively. For the mid- andmore » near-infrared, the approximation can be simplified such that the real part of the optical conductivity is extracted without the need for a parameterization of the optical conductivity. This direct extraction is shown for Fourier transform infrared (FTIR) transmittance measurements of CVD graphene on silicon in the photon energy range of 370–7000 cm{sup −1}. From the real part of the optical conductivity, the carrier density, mobility, and number of graphene layers are determined but also residue, originating from the graphene transfer, is detected. FTIR transmittance analyzed with the improved thin film approximation is shown to be a non-invasive, easy, and accurate measurement and analysis method for assessing the quality of graphene and can be used for other 2-D materials.« less

Diffuse optical tomography and spectroscopy of breast cancer and fetal brain

NASA Astrophysics Data System (ADS)

Choe, Regine

Diffuse optical techniques utilize light in the near infrared spectral range to measure tissue physiology non-invasively. Based on these measurements, either on average or a three-dimensional spatial map of tissue properties such as total hemoglobin concentration, blood oxygen saturation and scattering can be obtained using model-based reconstruction algorithms. In this thesis, diffuse optical techniques were applied for in vivo breast cancer imaging and trans-abdominal fetal brain oxygenation monitoring. For in vivo breast cancer imaging, clinical diffuse optical tomography and related instrumentation was developed and used in several contexts. Bulk physiological properties were quantified for fifty-two healthy subjects in the parallel-plate transmission geometry. Three-dimensional images of breast were reconstructed for subjects with breast tumors and, tumor contrast with respect to normal tissue was found in total hemoglobin concentration and scattering and was quantified for twenty-two breast carcinomas. Tumor contrast and tumor volume changes during neoadjuvant chemotherapy were tracked for one subject and compared to the dynamic contrast-enhanced MRI. Finally, the feasibility for measuring blood flow of breast tumors using optical methods was demonstrated for seven subjects. In a qualitatively different set of experiments, the feasibility for trans-abdominal fetal brain oxygenation monitoring was demonstrated on pregnant ewes with induced fetal hypoxia. Preliminary clinical experiences were discussed to identify future directions. In total, this research has translated diffuse optical tomography techniques into clinical research environment.