This PDF file contains the front matter associated with SPIE Proceedings Volume 12378, including the Title Page, Copyright information, Table of Contents and Conference Committee lists.

Motile cilia are hair-like microtubule-based organelles covering epithelial surfaces of multiple organ systems, including lungs, airways, kidneys, and fallopian tubes. Genetic alterations affecting cilia structure and motility are associated with ciliopathies affecting the physiology of multiple organs, including reduced fertility and a higher incidence of ectopic pregnancies. Motile cilia beat periodically to propel fluids, mucus, and cells along the epithelial surfaces. The ciliary beating is coordinated between neighboring cells. Due to a phase shift, the beat of cilia forms a wave propagating along the surface, which is called the metachronal wave. While the clinical importance of cilia and their coordinated function is well recognized, this function is very poorly studied due to the lack of cilia imaging methods. Previously, we established a functional OCT method for mapping cilia and cilia beat frequency within the mouse fallopian tube in vivo, volumetrically, through the tissue layers. That method was based on the analysis of periodic OCT intensity fluctuations in pixels corresponding to cilia. Building on that method, here we present the visualization and quantification of cilia metachronal wave, by spatio-temporal analysis of ciliary beat phase propagation. This study presented the first quantitative approach for measuring cilia metachronal waves through tissue layers. This method gives unique access to cilia function in the mammalian fallopian tube in vivo, as demonstrated here. It can also be directly adapted to investigating coordinated cilia behaviors in multiple organ systems toward better-managing pathologies associated with ciliopathies.

Neurosurgical interventions benefit greatly from monitoring of cerebral blood flow (CBF). Laser speckle contrast imaging (LSCI) is a label-free optical imaging technique that can provide continuous, high spatiotemporal maps of flow dynamics, allowing clinicians to monitor changes in CBF without any interruption to the surgical workflow. Multi-exposure speckle imaging (MESI) is an extension of LSCI that collects speckle images at numerous camera exposure times to create reproducible and quantifiable measurements of flow, through a more robust calculation of the correlation time constant. This work is focused on investigating whether the chosen spacing of the camera exposure times can impact the resulting computation of the inverse correlation time (ICT). A microfluidic phantom using a pressure-regulated flow control system is used to generate a 5-step and 7-step flow profile. MESI data is collected with three different exposure time spacings; logarithmic-spaced, linear-spaced, and the ad hoc exposure times from previous research. Using a nonlinear least squares fitting algorithm we fit the measured data to solve for the speckle correlation time constant at each MESI frame. We compare the quantified flow, based on the computed ICT for each exposure time collection method. These results suggest that future research and clinical adaptations should consider implementing logarithmic -spaced exposure times for MESI as it may provide more reliable and accurate estimates of flow, as well as faster acquisition times, without the need for specially chosen exposure times.

Progress has been made in laser speckle contrast imaging (LSCI) of microcirculatory blood flow for biology and medicine. However, the underlying reason for occurrence of movement artefacts (MA) that compromises effective use of LSCI remains largely unexplored. Here, employing a dual-camera setup for both speckle imaging and movement tracking, we validate our analytical model that is based on optical Doppler effect for predication of speckle contrast drop as a function of applied translational speed. We perform both motorized and handheld experiments where planar and scrambled wave illumination schemes have been examined. Experimental data points fairly match the theoretical predictions. These findings indicate that the vision-based movement detection during handheld LSCI is a preferable option. Moreover, the proposed analytical model is promising for further exploration of MA in order to realize a reliable handheld LSCI.

Obtaining parameters that characterize cerebral fluid interactions in the human brain is of high interest particularly as regards studies of the glymphatic system and in relation to neurodegeneration diseases. Near-infrared spectroscopy (NIRS) based techniques commonly measure cerebral hemodynamics using a combination of wavelengths approximately between 650 nm and 950 nm, where light is to a lesser amount attenuated by water, enabling light to reach the brain. By adding a wavelength that is dominantly absorbed by water, while still penetrating below skull, we may have a possibility to measure also cortical water concentration changes, particularly dynamics of the cerebrospinal fluid (CSF) volume, which have been connected to brain’s waste removal system. In this study, we show based on in vivo human experiments that small dynamical variations in the CSF layer, between the human skull and brain cortex determined by MRI, correlate with near infrared (NIR) light intensity changes particularly above 960 nm when measured at long (< 3 cm) source-detector distance. In addition, based on the previously reported anti-correlation between total haemoglobin (HbT) and water signal fluctuations measured with NIRS, we further investigated the differences in the anti-correlations when using short (< 2 cm) and long source-detector distances. In general, at a short source-detector distance the NIRS measurement volume does not reach a depth below human skull. In consequence, our results from 12 healthy subjects show greater anti-correlation between HbT and water when using a long source-detector distance, supporting the idea that NIRS can be used to monitor also human cortical water fluctuations non-invasively.

The use of multimodality approaches may benefit from simultaneous or sequential optical and magnetic resonance (MR) imaging applied to the same tissue volume. Previously observed in vivo optical clearing (OC) effect of MRI contrast agent was investigated with a goal of quantifying the effect of gadobutrol (GB) and biocompatible compositions containing GB as means of improving fluorescence intensity imaging (FI) in a rodent model of cancer. MRI was also explored as a technique enabling localization of the tumor volumes affected by intravenous administration of GB performed for the purpose of achieving an OC effect. Xenografting of cells expressing a red fluorescent marker TagRFP in athymic mice resulted in subcutaneous tumors that were subjected to 1H MRI at 1T by applying T1w-3D gradient-echo (GRE) pulse sequences. MRI allowed to measure the longitudinal changes in MR signal intensity that were sufficient for ROI analysis after manual or automated image segmentation. By performing topical application of an OC compositions, which contained 1.0 M or 0.7 M GB mixed with water and dimethyl sulfoxide (DMSO) onto the skin similar tumor MRI signal enhancement by 30–40% within the first 15 min was achieved. Over time, the effect of GB-mediated OC on FI and tumor/background ratio decreased. The application of 0.7 M GB OC mixture in contrast, to concentrated 1.0 M GB resulted in a continuous increase of both tumor red fluorescence as well as of the tumor/background ratio within 15 min and 1 h post cutaneous application. By applying T1w-3D GRE MR it was determined that concentrated 1.0 M GB resulted in MR signal loss measured in the skin due to high magnetic susceptibility. However, the MR signal loss was colocalized with the OC effect in tumor tissue. Intravenous injection of GB at a dose of 0.3 mmol/kg resulted in a rapid and temporary increase of FI by 40%. In conclusion, low-field MRI proved to be useful for performing in vivo imaging of GB-containing OC compositions behavior after local and systemic applications in cancer models and supported the observation of FI longitudinal changes in vivo.

The clinical use of optical methods for in vivo skin imaging is limited by skin strong scattering properties, which reduce image contrast and probing depth. The efficiency of optical methods can be improved by optical clearing (OC). However, for the use of optical clearing agents (OCAs) in a clinical setting, compliance with acceptable non-toxic concentrations is required. Optical clearing of in vivo human skin, combined with physical and chemical methods to enhance skin permeability to OCAs, was performed to determine the clearing-effectiveness of biocompatible OCAs using Line-field Confocal Optical Coherence Tomography (LC-OCT) imaging. Nine types of OCAs mixtures were used in association with dermabrasion and sonophoresis for optical clearing protocol on three volunteers hand skin. From 3D images obtained every five minutes for 40 minutes, the intensity and contrast parameters were extracted to assess their changes during the clearing process and evaluate each OCAs mixture’s clearing efficacy. LC-OCT images average intensity and contrast increased over the entire skin depth with all OCAs. The best image contrast and intensity improvement was observed using the Polyethylene Glycol, Oleic Acid and Propylene Glycol mixture. Complex OCAs featuring reduced component. concentrations that meet drug regulation-established biocompatibility requirements were developed and proved to induce. significant skin tissues clearing. By allowing deeper observations and higher contrast, such OCAs in combination with physical and chemical permeation enhancers may improve LC-OCT diagnostic efficacy.

Prenatal alcohol exposure (PAE) is a leading cause of developmental disabilities worldwide and thus, is one of the best-known causes of preventable birth defects. Its effects can persist throughout life as physical and cognitive growth and development deficits. Previous studies have demonstrated that the acute effects of prenatal alcohol exposure on fetal brain vasculature diminish brain growth and decrease cerebrovascular blood flow. In this study, we use correlation mapping optical coherence angiography to assess the dose-effect relationship of prenatal alcohol exposure on fetal brain vasculature in utero in a mouse model (C57BL/6J). We evaluated multiple alcohol dosages (1.5 g/kg, 3.0 g/kg, and 4.5 g/kg) at gestational day (GD) 14.5 followed immediately by imaging at GD 14.5. We also studied multiple dosing effects by administering ethanol via intragastric gavage at GD 12.5, 13.5, and 14.5 for each dose (1.5 g/kg, 3.0 g/kg, and 4.5 g/kg) followed by imaging at GD 14.5. Results show vasoconstriction of the main imaged blood vessel after dosing for three consecutive days. When the embryo was exposed to the lowest dose, 1.5 g/kg of ethanol, there was a greater decrease in the main blood vessel diameter, compared to the highest dose, 4.5 g/kg of ethanol. For the acute dosing studies, where a single ethanol dose was administered at GD 14.5, the results show a higher percentage change in vessel diameter over time for 4.5 g/kg, which was the highest dose, but with a higher initial percentage change at a lower dose. The multiple dose and single dose exposure to ethanol results demonstrated significant changes in fetal brain vasculature. Multiple dosing of prenatal alcohol exposure shows a significant effect in the vasculature for each dosage, demonstrating the dose-effect relationship of multiple ethanol exposure on embryo brain vasculature compared to a single dose exposure.

Alterations in cardiac development lead to embryonic lethality or congenital heart defects, which affect about 1% of all newborns worldwide. The heart is critical for blood circulation to transport oxygen, nutrients, and waste, but proper blood flow is also key to cardiac development. Early heart contractility and blood flow are suggested by multiple studies to be biomechanical factors that regulate cardiovascular development. Therefore, the ability to reconstruct the dynamic patterns of blood flow in the developing embryos is important to understanding the biomechanical regulation of heart development and improved management of congenital heart defects. Toward this goal, optical coherence tomography (OCT) imaging of mouse embryonic cardiodynamics and novel OCT-based functional analysis methods are actively being developed. Here, we present the development of quantitative OCT angiography toward direction-independent, spatially and temporally resolved blood flow analysis in embryonic vascular structures, which could potentially be expanded to the heart. In contrast to adult blood, individual blood cells can be visualized within the embryonic cardiovascular system. Our approach takes advantage of this feature as well as the periodicity of the cardiac cycle. We demonstrate a capability for spatially resolved flow dynamics in embryonic vasculature in relation to the heartbeat phase. Potentially, the presented method can be expanded to 4D (3D + time) quantitative OCT angiography in the beating heart to enable biomechanical studies.

Photoplethysmography (PPG) waveform is primary formed by absorbance and scattering of light caused by blood volume changes in the microvascular bed of tissue. The volume of blood is constantly changing due to cardiac activity and various low frequency physiological components, such as, respiration and sympathetic nervous system. Importantly, elastic property of blood vessels and blood pressure also greatly affects the volume of blood and thus PPG waveform inversely contains information on vessel elasticity and pressure that has been studied using e.g., pulse decomposition analysis (PDA) models. We emulated PPG waveform by using a simplified mock circulatory loop mimicking human circulatory system to study how changing elasticity of 3D printed vessels and blood pressure affects the PPG waveform, aiming to validate presented pulse decomposition analysis model for estimating vessel stiffness and blood pressure. The circulatory system built for the study is controlled via custom-made LabView software. Pumping frequency, pressure and flow of blood mimicking liquid can be controlled and accurately measured for a reference. The main analysis relied on the PDA that extracted five log-normal pulses for further analysis. In particular, we focused on the centre parameter of each log-normal pulse and observed it changes depending on the emulated parameters.

A portable, compact and modular small-animal imaging platform is designed for measurement of deep tissue and superficial cerebral blood flow. The platform is integrated with optics, data acquisition unit, display unit and on-board single-board computer (SBC) that supports a Graphical User Interface (GUI). It also contains a customizable stereotaxic frame for both mice and rats for housing the animals along with provision for anesthesia, pulse oximeters and temperature probes. Functional studies have been conducted in the olfactory bulb and somatosensory cortex in mice brain using the imaging platform to measure relative cerebral blood flow (rCBF). We show longitudinal blood flow changes in the pre-cortical brain region associated with multiple odours, categorized broadly into ester, phenyl propanoid and terpenoids chemical group. A forepaw stimulation study has also been conducted to show blood flow changes in the cortical region of the brain. The surface as well as depth-wise blood flow changes due to the stimulations have been shown using Laser Speckle Contrast Imaging (LSCI) and Multi-speckle Diffuse Correlation Tomography (M-DCT) respectively.

Non-invasive diagnosis of skin pathologies as skin cancer using optical methods has become increasingly common in recent years. However, the related skin data processing is often quite complex, and the way in which this step is carried out can significantly affect the final results. This study presents the results of diffuse reflectance spectra (with spectral range of the emission source is 300-800 nm) and autofluorescence spectra (with 7 autofluorescence excitation wavelengths in the 360-430 nm range) obtained in vivo from precancerous and benign skin lesions of various types (compensatory hyperplasia, atypical hyperplasia and dysplasia). The skin lesions were modelled using a preclinical model in mice. Spectra were taken in the range of 317 - 789 nm at three different source-detector separations: 271, 536 and 834 μm. The spectra obtained were processed using statistical feature extraction techniques, traditional machine learning (support vector machine, linear discriminant analysis, k-nearest neighbors) and deep learning methods (artificial neural network, convolutional neural network, autoencoder). This study presents a comparison of the performance of these methods and their combinations for multiclass classification of skin lesions.