Comparison of numerical-integration-based methods for blood flow estimation in diffuse correlation spectroscopy.

Background And Objective: Diffuse correlation spectroscopy (DCS) is an optical blood flow monitoring technology that has been utilized in various biomedical applications. In signal processing of DCS, nonlinear fitting of the experimental data and the theoretical model can be a hindrance in real-time blood flow monitoring. As one of the approaches to resolve the issue, INISg1, the inverse of numerical integration of squared g (a normalized electric field autocorrelation function), that could surpass the state-of-the-art technique at the time in terms of signal processing speed, has been introduced.

Sensing of triglyceride concentration in blood solution using photoacoustic microscopy.

The level of triglyceride (TG) in blood is essential to human health, and hypertriglyceridemia (TG level > 150 mg/dL) would lead to cardiovascular disease and acute pancreatitis that threaten human life. Routine methods for measuring the TG level in blood depend on a lipid panel blood test, which is invasive and not convenient. Here, we use photoacoustic (PA) microscopy to test the PA amplitude of blood solutions (based on hemoglobin powder as well as flowing sheep blood) with different TG concentrations.

Implantable QR code subcutaneous microchip using photoacoustic and ultrasound microscopy for secure and convenient individual identification and authentication.

Individual identification and authentication techniques are merged into many aspects of human life with various applications, including access control, payment or banking transfer, and healthcare. Yet conventional identification and authentication methods such as passwords, biometrics, tokens, and smart cards suffer from inconvenience and/or insecurity. Here, inspired by quick response (QR) code and implantable microdevices, implantable and minimally-invasive QR code subcutaneous microchips (QRC-SMs) are proposed to be an effective approach to carry useful and private information, thus enabling individual identification and authentication.

Use of Hypoxic Respiratory Challenge for Differentiating Alzheimer's Disease and Wild-Type Mice Non-Invasively: A Diffuse Optical Spectroscopy Study.

Alzheimer's disease is one of the most critical brain diseases. The prevalence of the disease keeps rising due to increasing life spans. This study aims to examine the use of hemodynamic signals during hypoxic respiratory challenge for the differentiation of Alzheimer's disease (AD) and wild-type (WT) mice.

Blood flow estimation via numerical integration of temporal autocorrelation function in diffuse correlation spectroscopy.

Background And Objective: Diffuse correlation spectroscopy (DCS) is an optical technique widely used to monitor blood flow. Recently, efforts have been made to derive new signal processing methods to minimize the systems used and shorten the signal processing time. Herein, we propose alternative approaches to obtain blood flow information via DCS by numerically integrating the temporal autocorrelation curves.

Investigation of nonlinear photoacoustic microscopy using a low-cost infrared lamp.

Nonlinear photoacoustic microscopy (PAM) is a novel approach to enhance contrast and resolution. In this study, a low-cost infrared (IR) lamp as a simple approach for nonlinear PAM is demonstrated. Numerical simulations are first performed to verify the nonlinear photoacoustic effect under steady heating for two cases: (a) Differentiation of absorbers with different Grüneisen coefficients; (b) enhancement of photoacoustic amplitude.

Changes of Apomorphine-Induced Vaginal Hemodynamics in an Ovariectomized Rat Model Using Near-Infrared Spectroscopic Probe.

Introduction: Female sexual arousal disorder (FSAD) can be caused by the change in vaginal structure due to the decline of estrogen and one of the main symptoms is vaginal dryness. FSAD is a prevalent problem afflicting women all over the world and thus the interest is growing on the matter, but related studies of monitoring FSAD using a non-invasive optical method barely have been carried out.

Aim: This study aims to investigate the longitudinal changes in female sexual arousal response induced by apomorphine (APO) administration in the ovariectomized rat using near-infrared spectroscopy (NIRS) probe.

Photoacoustic-fluorescence microendoscopy in vivo.

A miniature endoscope capable of imaging multiple tissue contrasts in high resolution is highly attractive, because it can provide complementary and detailed tissue information of internal organs. Here we present a photoacoustic (PA)-fluorescence (FL) endoscope for optical-resolution PA microscopy (PAM) and FL microscopy (FLM). The endoscope with a diameter of 2.

Recent advances toward clinical applications of photoacoustic microscopy: a review.

Photoacoustic imaging (PAI) is an emerging technology that has been dramatically developed in the last decade. PAI, a combination of optical illumination and ultrasound detection, allows us to achieve fine resolution and obtain fruitful information of endogenous and exogenous chromophores. Among PAI imaging techniques, photoacoustic computed tomography (PACT) has been extensively used in human studies due to its deep tissue penetration (several centimeters).

Design of an Optical Probe to Monitor Vaginal Hemodynamics during Sexual Arousal.

An optical probe was developed to measure the change of oxy-hemoglobin (OHb), deoxy- hemoglobin (RHb), and total hemoglobin (THb) along with temperature from the vaginal wall of female rats. Apomorphine (APO, 80 μg/kg) was administered to elicit sexual arousal in female Sprague Dawley rats (SD, 180-200 g). The behavior changes caused by APO administration were checked before monitoring vaginal responses.

Change of tumor vascular reactivity during tumor growth and postchemotherapy observed by near-infrared spectroscopy.

Breast cancer is one of the most common cancers in females. To monitor chemotherapeutic efficacy for breast cancer, medical imaging systems such as x-ray mammography, computed tomography, magnetic resonance imaging, and ultrasound imaging have been used. Currently, it can take up to 3 to 6 weeks to see the tumor response from chemotherapy by monitoring tumor volume changes.

Low-cost compact diffuse speckle contrast flowmeter using small laser diode and bare charge-coupled-device.

We report a low-cost compact diffuse speckle contrast flowmeter (DSCF) consisting of a small laser diode and a bare charge-coupled-device (CCD) chip, which can be used for contact measurements of blood flow variations in relatively deep tissues (up to ∼ 8  mm). Measurements of large flow variations by the contact DSCF probe are compared to a noncontact CCD-based diffuse speckle contrast spectroscopy and a standard contact diffuse correlation spectroscopy in tissue phantoms and a human forearm. Bland–Altman analysis shows no significant bias with good limits of agreement among these measurements: 96.

Simultaneous blood flow and blood oxygenation measurements using a combination of diffuse speckle contrast analysis and near-infrared spectroscopy.

A combined diffuse speckle contrast analysis (DSCA)-near-infrared spectroscopy (NIRS) system is proposed to simultaneously measure qualitative blood flow and blood oxygenation changes in human tissue. The system employs an optical switch to alternate two laser sources at two different wavelengths and a CCD camera to capture the speckle image. Therefore, an optical density can be measured from two wavelengths for NIRS measurements and a speckle contrast can be calculated for DSCA measurements.