Optical tuning of copolymer-in-oil tissue-mimicking materials for multispectral photoacoustic imaging.

. The availability of tissue-mimicking materials (TMMs) for manufacturing high-quality phantoms is crucial for standardization, evaluating novel quantitative approaches, and clinically translating new imaging modalities, such as photoacoustic imaging (PAI). Recently, a gel comprising the copolymer styrene-ethylene/butylene-styrene (SEBS) in mineral oil has shown significant potential as TMM due to its optical and acoustic properties akin to soft tissue.

Two-layer reconstruction of Raman spectra in diffusive media based on an analytical model in the time domain.

We derive and validate an analytical model that describes the migration of Raman scattered photons in two-layer diffusive media, based on the diffusion equation in the time domain. The model is derived under a heuristic approximation that background optical properties are identical on the excitation and Raman emission wavelengths. Methods for the reconstruction of two-layer Raman spectra have been developed, tested in computer simulations and validated on tissue-mimicking phantom measurements data.

Breast Cancer Diagnosis Using Extended-Wavelength-Diffuse Reflectance Spectroscopy (EW-DRS)-Proof of Concept in Ex Vivo Breast Specimens Using Machine Learning.

This study aims to investigate the feasibility of using diffuse reflectance spectroscopy (DRS) to distinguish malignant breast tissue from adjacent healthy tissue, and to evaluate if an extended-wavelength range (450-1550 nm) has an advantage over the standard wavelength range (450-900 nm). Multivariate statistics and machine learning algorithms, either linear discriminant analysis (LDA) or support vector machine (SVM) are used to distinguish the two tissue types in breast specimens (total or partial mastectomy) from 23 female patients with primary breast cancer. EW-DRS has a sensitivity of 94% and specificity of 91% as compared to a sensitivity of 40% and specificity of 71% using the standard wavelength range.

Remote Nanoscopy with Infrared Elastic Hyperspectral Lidar.

Monitoring insects of different species to understand the factors affecting their diversity and decline is a major challenge. Laser remote sensing and spectroscopy offer promising novel solutions to this. Coherent scattering from thin wing membranes also known as wing interference patterns (WIPs) have recently been demonstrated to be species specific.

A biophotonic platform for quantitative analysis in the spatial, spectral, polarimetric, and goniometric domains.

Advanced instrumentation and versatile setups are needed for understanding light interaction with biological targets. Such instruments include (1) microscopes and 3D scanners for detailed spatial analysis, (2) spectral instruments for deducing molecular composition, (3) polarimeters for assessing structural properties, and (4) goniometers probing the scattering phase function of, e.g.

Distinguishing tumor from healthy tissue in human liver ex vivo using machine learning and multivariate analysis of diffuse reflectance spectra.

The aim of this work was to evaluate the capability of diffuse reflectance spectroscopy to distinguish malignant liver tissues from surrounding tissues and to determine whether an extended wavelength range (450-1550 nm) offers any advantages over using the conventional wavelength range. Furthermore, multivariate analysis combined with a machine learning algorithm, either linear discriminant analysis or the more advanced support vector machine, was used to discriminate between and classify freshly excised human liver specimens from 18 patients. Tumors were distinguished from surrounding liver tissues with a sensitivity of 99%, specificity of 100%, classification rate of 100% and a Matthews correlation coefficient of 100% using the extended wavelength range and a combination of principal component analysis and support vector techniques.

Local Mapping of Polar Ionospheric Electrodynamics.

An accurate description of the state of the ionosphere is crucial for understanding the physics of Earth's coupling to space, including many potentially hazardous space weather phenomena. To support this effort, ground networks of magnetometer stations, optical instruments, and radars have been deployed. However, the spatial coverage of such networks is naturally restricted by the distribution of land mass and access to necessary infrastructure.

Hyperspectral and Laser Speckle Contrast Imaging for Monitoring the Effect of Epinephrine in Local Anesthetics in Oculoplastic Surgery.

Purpose: Epinephrine is used in local anesthetics to induce vasoconstriction and thus reduce bleeding and prolong the anesthetic effect. Finding the optimal delay between the administration of the anesthetic and skin incision to ensure vasoconstriction and minimize bleeding is important and has recently become the subject of debate. This is the first study to assess blood perfusion and oxygen saturation (sO 2 ) simultaneously in response to a local anesthetic containing epinephrine in human oculoplastic surgery.

Photoacoustic imaging for the monitoring of local changes in oxygen saturation following an adrenaline injection in human forearm skin.

Clinical monitoring of blood oxygen saturation (sO) is traditionally performed using optical techniques, such as pulse oximetry and diffuse reflectance spectroscopy (DRS), which lack spatial resolution. Photoacoustic imaging (PAI) is a rapidly developing biomedical imaging technique that is superior to previous techniques in that it combines optical excitation and acoustic detection, providing a map of chromophore distribution in the tissue. Hitherto, PAI has primarily been used in preclinical studies, and only a few studies have been performed in patients.

Automatic threshold selection algorithm to distinguish a tissue chromophore from the background in photoacoustic imaging.

The adaptive matched filter (AMF) is a method widely used in spectral unmixing to classify different tissue chromophores in photoacoustic images. However, a threshold needs to be applied to the AMF detection image to distinguish the desired tissue chromophores from the background. In this study, we propose an automatic threshold selection (ATS) algorithm capable of differentiating a target from the background, based on the features of the AMF detection image.

Photoacoustic imaging of the spatial distribution of oxygen saturation in an ischemia-reperfusion model in humans.

Photoacoustic imaging (PAI) is a novel hybrid imaging technique that combines the advantages of optical and ultrasound imaging to produce hyperspectral images of the tissue. The feasibility of measuring oxygen saturation (sO) with PAI has been demonstrated pre-clinically, but has limited use in humans under conditions of ischemia and reperfusion. As an important step towards making PAI clinically available, we present a study in which PAI was used to estimate the spatial distribution of sO during and after occlusion of the finger of eight healthy volunteers.

Mercury in neonatal and juvenile blacktip sharks (Carcharhinus limbatus). Part II: Effects assessment.

As apex predators, blacktip sharks (Carcharhinus limbatus) are highly susceptible to biomagnified mercury (Hg) particularly in the Gulf of Mexico (GOM), which is known to contain fishes and invertebrates with elevated Hg levels. Blacktip sharks occur in the GOM year-round and are heavily fished both commercially and recreationally, but little is known about how Hg affects the species. In this study, blood, muscle, liver, and kidney samples were collected from neonatal (n = 57) and juvenile (n = 13) blacktip sharks in Charlotte Harbor, Florida.

Mercury in neonatal and juvenile blacktip sharks (Carcharhinus limbatus). Part I: exposure assessment.

Elasmobranchs are exposed to mercury (Hg) through a variety of pathways in the environment. This study assessed maternal offloading and diet-based Hg exposure for neonatal and juvenile blacktip sharks (Carcharhinus limbatus) from Charlotte Harbor located along southwest Florida's coast, a recognized Hg hotspot. Neonates (n = 57) had highest total Hg (THg) concentrations in the kidney (0.

Time-scale dependence of solar wind-based regression models of ionospheric electrodynamics.

The solar wind influence on geospace can be described as the sum of a directly driven component, or dayside reconnection, and an unloading component, associated with the release of magnetic energy via nightside reconnection. The two processes are poorly correlated on short time scales, but exactly equal when averaged over long time windows. Because of this peculiar property, regression models of ionospheric electrodynamics that are based on solar wind data are time scale specific: Models derived from 1 min resolution data will be different from models derived from hourly, daily, or monthly data.

Characterization and modeling of acousto-optic signal strengths in highly scattering media.

Ultrasound optical tomography (UOT) is an imaging technique based on the acousto-optic effect that can perform optical imaging with ultrasound resolution inside turbid media, and is thus interesting for biomedical applications, e.g. for assessing tissue blood oxygenation.

Extended-wavelength diffuse reflectance spectroscopy with a machine-learning method for in vivo tissue classification.

Objectives: An extended-wavelength diffuse reflectance spectroscopy (EWDRS) technique was evaluated for its ability to differentiate between and classify different skin and tissue types in an in vivo pig model.

Materials And Methods: EWDRS recordings (450-1550 nm) were made on skin with different degrees of pigmentation as well as on the pig snout and tongue. The recordings were used to train a support vector machine to identify and classify the different skin and tissue types.

Clinical Translation of a Novel Photoacoustic Imaging System for Examining the Temporal Artery.

The objective was to provide a clinical setup for photoacoustic imaging (PAI) of the temporal artery in humans and to describe the challenges encountered and methods of overcoming them. The temporal artery was examined in seven patients with suspect giant-cell arteritis (GCA), both in vivo and ex vivo, and the results were compared to that of histology. To adapt PAI to the human studies, the transducer was fixed to an adjustable arm to reduce motion artifacts, and a stepping motor was developed to enable 3-D scanning.

Extended-wavelength diffuse reflectance spectroscopy for a comprehensive view of blood perfusion and tissue response in human forearm skin.

Background: The aim of this study was to investigate the possibility of using extended-wavelength diffuse reflectance spectroscopy (EW-DRS) to measure tissue response related to blood perfusion. The study was performed on a model that we have previously found to be useful for studying techniques for perfusion monitoring following the injection of epinephrine in a local anesthetic in the human forearm.

Methods: Nine healthy subjects were included in the study.

The human yolk sac size reflects involvement in embryonic and fetal growth regulation.

Introduction: The human yolk sac provides the embryo with stem cells, nutrients, and gas exchange. We hypothesized that more maternal resources, reflected in body size and body composition, would condition a a larger yolk sac, ensuring resources for the growing embryo. Thus, we aimed to determine the relation between maternal size in early pregnancy and yolk sac size.

Hypoperfusion following the injection of epinephrine in human forearm skin can be measured by RGB analysis but not with laser speckle contrast imaging.

Background: The time taken for epinephrine to achieve its optimal effect during local anesthesia has recently become the subject of debate. The time from injection to commencement of surgery is traditionally quoted to be 7 to 10 min, while recent reports claim that it may take 30 min to achieve maximum hypoperfusion, which would prolong the time required for surgical procedures. The discrepancy may be related to difficulties associated with the techniques used to measure blood perfusion.

Intraoperative liver steatosis characterization using diffuse reflectance spectroscopy.

Background: Liver steatosis is associated with poor outcome after liver transplantation and liver resection. There is a need for an accurate and reliable intraoperative tool to identify and quantify steatosis. This study aimed to investigate whether surface diffuse reflectance spectroscopy (DRS) measurements could detect liver steatosis on humans during liver surgery.

Identification of tumor margins using diffuse reflectance spectroscopy with an extended-wavelength spectrum in a porcine model.

Objective: A novel extended-wavelength diffuse reflectance spectroscopy (EWDRS) technique is being developed for future clinical non-invasive tumor margin delineation. In this study, the ability of EWDRS to identify the margins of pigmented skin lesions in an in vivo pig model was evaluated.

Materials And Methods: Extended-wavelength diffuse reflectance spectroscopy recordings (350-1550 nm) were made on 13 pigmented skin lesions and non-pigmented skin, as a reference.

Optimal Epinephrine Concentration and Time Delay to Minimize Perfusion in Eyelid Surgery: Measured by Laser-Based Methods and a Novel Form of Extended-Wavelength Diffuse Reflectance Spectroscopy.

Objective: This study investigates the hypoperfusion effects of epinephrine in local anesthesia in eyelid surgery. A novel form of extended-wavelength diffuse reflectance spectroscopy was evaluated.

Methods: Blood perfusion in porcine eyelid flaps was measured using laser Doppler velocimetry and laser speckle contrast imaging, whereas the tissue response was measured using diffuse reflectance spectroscopy with a broad spectrum (450-1550 nm).

Diffuse Reflectance Spectroscopy for Surface Measurement of Liver Pathology.

Background: Liver parenchymal injuries such as steatosis, steatohepatitis, fibrosis, and sinusoidal obstruction syndrome can lead to increased morbidity and liver failure after liver resection. Diffuse reflectance spectroscopy (DRS) is an optical measuring method that is fast, convenient, and established. DRS has previously been used on the liver with an invasive technique consisting of a needle that is inserted into the parenchyma.

Perfluoroalkylated compounds induce cell death and formation of reactive oxygen species in cultured cerebellar granule cells.

The present communication investigates the effects of different perfluoroalkylated compounds (PFCs) on formation of reactive oxygen species (ROS) and cell death in cultured cerebellar granule cells. This allows direct comparison with similar effects found for other environmental contaminants like polychlorinated biphenyls and brominated flame-retardants. The increase in ROS formation and cell death was assayed using the fluorescent probe 2,7-dichlorofluorescin diacetate (DCFH-DA) and the trypan blue exclusion assay.