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This study presents a miniaturized head-mount optical coherence tomography (OCT) system tailored for high-resolution brain imaging in freely moving mice, providing an advanced noninvasive imaging tool in neuroscience research. Leveraging optical coherence tomography technology, the system enables depth-resolved imaging and integrates functional OCT extensions, including angiography and Doppler imaging. Remarkably lightweight at 1.5 g, the device allows for the preservation of natural mouse behavior during imaging sessions. With a maximum 4 × 4 mm field of view and 7.4 μm axial resolution, the system offers reliable imaging capabilities. Noteworthy features include focal adjustability, rotary joint integration for fiber-twist-free operation, and a high-speed swept-source OCT laser at 200 kHz, facilitating real-time imaging. By providing insights into brain mechanisms and neurological disorders without disrupting natural behavior, this innovative system holds promise as a powerful tool in neuroscience research. Its compact design and comprehensive imaging capabilities make it well-suited for studying various brain regions and dynamic processes, contributing significantly to our understanding of brain function and pathology.

Background: Effective drug delivery of nanomedicines to targeted sites remains challenging. Given that hypobaric hypoxia and hyperbaric oxygen exposure can significantly change pharmacokinetics of drugs, it is interesting to determine whether they can regulate tissue distribution of nanomedicine, especially in tumor, for enhanced cancer therapy. Results: Hypobaric hypoxia exposure improved the pharmacokinetics of paclitaxel-loaded liposomes and facilitated their distribution in the heart and liver, whereas hyperbaric oxygen exposure did not benefit and even impaired the pharmacokinetics and distribution. Particularly, both hypobaric hypoxia and hyperbaric oxygen exposure could not improve the distribution in subcutaneous tumor. Thus, we constructed orthotopic liver tumor model and discussed whether high distribution of the liposomal nanomedicine in the liver, facilitated by hypobaric hypoxia exposure, could ensure their effective accumulation in liver tumor for enhanced cancer therapy. Conclusions: The liposomal nanomedicine with adjuvant hypobaric hypoxia exposure significantly inhibited the growth of orthotopic liver tumor for prolonged survival time, achieved by hypobaric hypoxia-promoted accumulation at tumor sites of the liver. It might be the first example of the application of adjuvant intermittent hypobaric hypoxia exposure in treating liver cancer.

Photo-mediated ultrasound therapy (PUT) is a novel antivascular therapeutic modality based on cavitation-induced bioeffects. During PUT, synergistic combinations of laser pulses and ultrasound bursts are used to remove the targeted microvessels selectively and precisely without harming nearby tissue. In the current study, an integrated system combining PUT and spectral domain optical coherence tomography (SD-OCT) was developed, where the SD-OCT system was used to guide PUT by detecting cavitation in real time in the retina of the eye.MethodWe first examined the capability of SD-OCT in detecting cavitation on a vascular-mimicking phantom and compared the results with those from a passive cavitation detector. The performance of the integrated system in treatment of choroidal microvessels was then evaluated in rabbit eyes in vivo.ResultsDuring the in vivo PUT experiments, several biomarkers at the subretinal layer in the rabbit eye were identified on OCT images. The findings indicate that, by evaluating biomarkers of treatment effect, real-time SD-OCT monitoring could help to avoid micro-hemorrhage, which is a potential major side effect.ConclusionReal-time OCT monitoring can thus improve the safety and efficiency of PUT in removing the retinal and choroidal microvasculature.

ObjectiveDrug induced sleep endoscopy (DISE) is often performed for pediatric obstructive sleep apnea (OSA) when initial diagnostic studies do not provide adequate information for therapy. However, DISE scoring is subjective and with limitations. This proof-of-concept study demonstrates the use of a novel long-range optical coherence tomography (LR-OCT) system during DISE of two pediatric patients.MethodsLR-OCT was used to visualize the airway of pediatric patients during DISE. At the conclusion of DISE, the OCT probe was guided in the airway under endoscopic visual guidance, and cross-sectional images were acquired at the four VOTE locations. Data processing involved image resizing and alignment, followed by rendering of three-dimensional (3D) volumetric models of the airways.ResultsTwo patients were included in this study. Patient one had 18.4%, 20.9%, 72.3%, and 97.3% maximal obstruction at velum, oropharynx, tongue base, and epiglottis, while patient two had 40.2%, 41.4%, 8.0%, and 17.5% maximal obstruction at these regions, respectively. Three-dimensional reconstructions of patients' airways were also constructed from the OCT images.ConclusionThis proof-of-concept study demonstrates the successful evaluation of pediatric airway during DISE using LR-OCT, which accurately identified sites and degrees of obstruction with respective 3D airway reconstruction.

Fractional-pixel CO2 laser therapy shows promise for treating the genitourinary syndrome of menopause (GSM). Nevertheless, it remains controversial in the field of female pelvic medicine. This is due to the inherent difficulties in obtaining noninvasive biopsies to evaluate the treatments efficacy and safety objectively. To address this challenge, we developed a noninvasive intravaginal optical coherence tomography (OCT)/OCT angiography (OCTA) endoscopic system, whose probe features a shape identical to the laser treatment probe. This system can provide high-resolution OCT images to identify the microstructure of vaginal tissue and visualize the vasculature network in vivo. We conducted clinical research on 25 post-menopausal patients with GSM. OCT/OCTA scans were acquired at four different locations of the vagina (distal anterior, distal posterior, proximal anterior, and proximal posterior) during the whole laser treatment session. A U-Net deep learning model was applied to segment the vaginal epithelium for assessing vaginal epithelial thickness (VET). Blood vessel density and VET were quantified to monitor the efficacy of fractional-pixel CO2 laser therapy. Statistical correlation analyses between these metrics and other clinical scores were conducted, validating the utility of our system. This OCT/OCTA endoscopic system has great potential to serve as a noninvasive biopsy tool in gynecological studies to screen, evaluate, and guide laser treatment for GSM.

ObjectiveOptical coherence elastography (OCE) was used to demonstrate the relationship between the elasticity of the optic nerve head (ONH) and different intraocular pressure (IOP) levels in an in-vivo rabbit model for the first time.MethodBoth ex-vivo and in-vivo rabbit ONH were imaged using OCE system. A mechanical shaker initiated the propagation of elastic waves, and the elasticity of the ONH was determined by tracking the wave propagation speed. The elasticity of the ONH under varying IOP levels was reconstructed based on the wave speed. Notably, the ONH exhibited increased stiffness with elevated IOP.ResultsIn the in-vivo rabbit models, the Young's modulus of ONH increased from 14 kPa to 81 kPa with the IOP increased from 15 mmHg to 35 mmHg. This revealed a positive correlation between the Young's modulus of the ONH and intraocular pressure.ConclusionThe OCE system proved effective in measuring the mechanical properties of ONH at different IOP levels, with validation in an in-vivo rabbit model.SignificanceConsidering ONH plays a critical role in vision and eye diseases, the capability to image and quantify in vivo ONH biomechanical properties has great potential to advance vision science research and improve the clinical management of glaucoma patients.

Clinical treatment of TNBC remains challenging, due to the lack of targeted therapies. As TNBC is highly hypoxic with higher HIF-1α expression than other subtypes, we fabricated hypoxia-responsive polymeric micelles co-loading drug and shRNA to treat TNBC by targeting hypoxic tumor microenvironment and subsequently targeting overexpressed HIF-1α under hypoxia. The micelles were assembled from methoxy-polyethylene glycol (mPEG) and poly-L-lysine (PLL) copolymer with AZO as a hypoxia-responsive bridge of mPEG and PLL. Once exposed to hypoxia, AZO bridge was cleaved, resulting in the disassembly of the micelles for rapid release. In vitro and in vivo results showed that the micelles enabled simultaneous delivery of drug and shRNA to hypoxic sites for site-specific rapid release, facilitated by sensitive response to hypoxia; hypoxia-responsive shRNA delivery effectively silenced HIF-1α and its downstream genes, which not only ameliorated the response of hypoxic tumor to drug, but also modulated tumor microenvironment for further improved drug and shRNA delivery; as a result, synergistic treatment of chemotherapy and HIF-1α targeted gene therapy inhibited the growth of primary TNBC tumor and its distant metastasis in a murine model of orthotopic TNBC. Together with their good biocompatibility, hypoxia-responsive polymeric micelles thus emerged as a safe, effective, and universally applicable drug and gene carrier for treatment of TNBC as well as other hypoxic tumors.

BackgroundThe coordination and the directional order of ciliary metachronal waves are the major factors that determine the effectiveness of mucociliary clearance (MCC). Even though metachronal waves play an essential part in immune response, clinical diagnostic tools and imaging techniques that can reliably and efficiently capture their spatial distribution and function are currently limited.MethodsWe present label-free high-speed visualization of ciliary metachronal wave propagations in freshly-excised tracheal explants using a spectrally-encoded interferometric microscope over a two-dimensional (2D) plane of 0.5 mm × 0.5 mm at an acquisition rate of 50 frame-per-second. Furthermore, phase-resolved enhanced dynamic (PHRED) analysis of time-series doppler images was performed, where spatial-temporal characteristics of cilia metachronal wave motions are revealed through frequency component analysis and spatial filtering.ResultsThe PHRED analysis of phase-resolved Doppler (PRD) images offers a capability to distinguish the propagation direction of metachronal waves, and quantitatively assess amplitude and dominant frequency of cilia beating at each spatial location. Compared to the raw PRD images, the phase-resolved dynamic wavefront imaging (PRDWI) method showed the direction and coordination of collective cilia movement more distinctively.ConclusionsThe PRDWI technique can have broad application prospects for the diagnosis of human respiratory diseases and evaluation of the curative effect of treatments and open new perspectives in biomedical sciences.

Chemical injuries to the cornea account for 11 to 22% of all ocular injuries. Acidic injuries are commonly due to sulfuric, hydrochloric, hydrofluoric, and battery acids, while basic injuries are commonly due to sodium hydroxide, chlorine bleach, and ammonia products. We have previously studied potential-driven electrochemical clearing (P-ECC) for alkaline injuries. In this study, we investigated the use of P-ECC on both acidic and alkaline injuries to determine its effect on restoring corneal transparency. Optical coherence tomography (OCT) was performed before and after P-ECC to determine adequate corneal clearing. Severity of chemical injury was measured through second harmonic generation (SHG) imaging. HCl or NaOH was applied to the corneas of New Zealand white rabbit globes. P-ECC was performed on opacified cornea while OCT imaging was simultaneously performed to evaluate depth resolved clarity. SHG imaging evaluated the structure of collagen before HCl or NaOH application and after P-ECC. Irrigation with water served as positive control. Native rabbit corneas were used as a negative control group. P-ECC induced clearing in the rabbit cornea, shown through OCT. Clearing occurred in regions where the working electrode made contact with the cornea. SHG imaging showed restoration of collagen fibril signal in P-ECC treated corneas compared to control. P-ECC is a potentially effective therapy for clearing acidic and alkaline corneal injuries. However, more ex-vivo experiments are required to determine the specific parameter for optimal clearing. In-vivo experiments are necessary to determine its potential for clinical use.

Mucociliary clearance is vital for preventing any foreign substances from entering the upper airway that can later develop into acute and/or chronic respiratory diseases. Therefore, it is essential to further advance our understanding of the mucociliary functions. Our lab has been able to make key developments in imaging cilia, specifically measuring cilia beat frequency, with phase-resolved Doppler optical coherence tomography. In this system, we have further developed the system by incorporating phase-resolved spectrally encoded interferometric microscopy (SIEM) system with an FDML laser with MHz sweep rate to image cilia with higher accuracy and to minimize motion artifacts. In addition, we have designed a compact handheld probe system with a GRIN lens for easier in vivo imaging. The development of this system will allow us to further investigate cilia dynamics and ultimately utilize the system for clinical applications.

Mucociliary clearance is an important physiological mechanism for clearing the upper airways. Previously, it has been shown that different disease processes and drugs affect ciliary beat frequency (CBF). Namely, epinephrine has been shown to accelerate CBF in various animal models. Additionally, phase contrast microscopy (PCM) and spectrally encoded interferometric microscopy (SEIM) have been used to image dynamic tissue of the upper airway. Herein, we explore the effects of epinephrine on human sinonasal mucosa through PCM and SEIM. Sinonasal mucosa was harvested from patients undergoing endoscopic sinus surgery (ESS). Tissue was imaged using PCM and SEIM, maintaining physiological temperature through the use of warmed HBSS and a heating plate. Videos were taken before addition of any drugs as baseline. Epinephrine was diluted to 1 mg/mL (1:1000) and 1mL of solution was introduced to the sinonasal mucosa. PCM and SEIM was performed after to determine effects of epinephrine on CBF. Data analysis was performed using MATLAB (Mathworks, Natick, Massachusetts). Human sinonasal mucosa, taken from various anatomic locations, showed CBF values on PCM and SEIM consistent with what has been shown in previous literature. Upon addition of epinephrine to sinonasal mucosa, a marked increase in CBF was observed in both PCM and SEIM. In conclusion, the addition of epinephrine to sinonasal mucosa increased ciliary beat frequency. This validates the use of SEIM for determining CBF in sinonasal tissues. Further studies include adding to our sample size to determine a more accurate magnitude of increase of CBF.

Genitourinary syndrome of menopause (GSM) negatively affects more than half of postmenopausal women. Energy-based therapy has been explored as a minimally invasive treatment for GSM; however, its mechanism of action and efficacy is controversial. Here, we report on a pilot imaging study conducted on a small group of menopause patients undergoing laser treatment. Intravaginal optical coherence tomography (OCT) endoscope was used to quantitatively monitor the changes in the vaginal epithelial thickness (VET) during fractional-pixel CO2 laser treatment. Eleven patients with natural menopause and one surgically induced menopause patient were recruited in this clinical study. Following the laser treatment, 6 out of 11 natural menopause patient showed increase in both proximal and distal VET, while two natural menopause patient showed increase in VET in only one side of vaginal tract. Furthermore, the patient group that showed increased VET had thinner baseline VET compared to the patients that showed decrease in VET after laser treatment. These results demonstrate the potential utility of intravaginal OCT endoscope in evaluating the vaginal tissue integrity and tailoring vaginal laser treatment on a per-person basis, with the potential to monitor other treatment procedures.

Photo-mediated Ultrasound Therapy (PUT), as a new anti-vascular technique, can promote cavitation activity to selectively destruct blood vessels with a significantly lower amount of energy when compared to energy level required by other laser and ultrasound treatment therapies individually. Here, we report the development of a high speed PUT system based on a 50-kHz pulsed laser to achieve faster treatment, decreasing the treatment time by a factor of 20. Furthermore, we integrated it with optical coherence tomography angiography (OCTA) for real time monitoring. The feasibility of the proposed OCTA-guided PUT was validated through in vivo rabbit experiments. The addition of OCTA to PUT allows for quantitative prescreening and real time monitoring of treatment response, thereby enabling implementation of individualized treatment strategies.

A nanosized zeolitic imidazolate framework-67 (ZIF-67) was employed for the adsorption of Cr(VI) under a neutral solution. It was discovered that the ZIF-67 demonstrated a high adsorption of Cr(VI) for the first (43.1 mg·g–1) and second run (40.2 mg·g–1). However, a self-sacrifice process of ZIF-67 was evidenced, possibly due to the oxidability of Cr(VI) and pH change, which resulted in a dramatically decrease of adsorption ability in the third run (16.6 mg·g–1). The adsorption process and its kinetics fitted the Langmuir model and pseudo-second-order rate equation and a multiple adsorption process was suggested.

There is increasing interest in developing a minimally invasive imaging modality to safely evaluate dynamic microscopic changes of the olfactory mucosa and cribriform foramina. Herein, we utilized three-dimensional (3D) optical coherence tomography (OCT) to characterize the ex vivo stratified substructure of olfactory mucosa in rabbits and create 3D reconstructed images of olfactory foramina. Olfactory mucosa and cribriform plates from four New Zealand White rabbits were dissected and imaged using two swept-source OCT systems: (1) 1.3-µm (μm) center wavelength, 100-nm bandwidth, 200-kHz sweep rate, and (2) 1.7-μm center wavelength, 120-nm bandwidth, 90-kHz sweep rate. Volumetric OCT images were compiled to create a 3D reconstruction of the cribriform plate. The ability of OCT to distinguish the olfactory mucosa substructure and foramina was compared to histology. To estimate imaging penetration depth of each system, the first-order exponential decays of depth-resolved intensity were calculated and compared using a paired t-test. Three-dimensional OCT depicted the stratified layered structures within the olfactory mucosa correlating with histology. The epithelium and lamina propria were measured to be 32 μm and 107 μm in 1.3-μm OCT compared to 30 μm and 105 μm in histology. Olfactory foramina were visualized via 3D reconstruction. The 1.7-μm system provided greater depth penetration compared to the 1.3-μm system, allowing for improved foramina visualization. We have shown that OCT can be used to image non-pathologic olfactory mucosa and foramina. Implications for this work include diagnostic and therapeutic potentials for neurorhinological and neurodegenerative diseases.

Tumor metastasis is a leading cause of breast cancer-related death. Taxane-loaded polymeric formulations, such as Genexol PM and Nanoxel M using poly(ethylene glycol)-poly(d,l-lactide) (PEG-PLA) micelles as drug carriers, have been approved for the treatment of metastatic breast cancer. Unfortunately, the physical instability of PEG-PLA micelles, leading to poor drug loading, premature drug leakage, and consequently limited drug delivery to tumors, largely hinders their therapeutic outcome. Inspired by the enantiomeric nature of PLA, this work developed stereocomplex PEG-PLA micelles through stereoselective interactions of enantiomeric PLA, which are further incorporated with a hypoxia-responsive moiety used as a hypoxia-cleavable linker of PEG and PLA, to maximize therapeutic outcomes. The results showed that the obtained micelles had high structural stability, showing improved drug loading for effective drug delivery to tumors as well as other tissues. Especially, they were capable of sensitively responding to the hypoxic tumor environment for drug release, reversing hypoxia-induced drug resistance and hypoxia-promoted cell migration for enhanced bioavailability under hypoxia. In vivo results further showed that the micelles, especially at a high dose, inhibited the growth of the primary tumor and improved tumor pathological conditions, consequently remarkably inhibiting its metastasis to the lungs and liver, while not causing any systemic toxicity. Hypoxia-responsive stereocomplex micelles thus emerge as a reliable drug delivery system to treat breast cancer metastasis.

In this paper, a new pyrroloquinoline-derivative-based fluorescent probe, PQP-1, was prepared for the selective detection of Lys in living cells and natural mineral water for drinking. PQP-1 exhibited high selectivity, low limit of detection, and a wide pH range. PQP-1 could be successfully applied for imaging Lys in living cells and in natural mineral water for drinking. We expect that PQP-1 will expand the detection reaction mechanism and the practical biological applications of Lys.

Mucociliary clearance facilitated by healthy cilia beating is crucial to normal upper airway function. Phase-contrast microscopy (PCM) is the current golden standard for measuring ciliary beat frequency (CBF) and has limitations. With PCM, one cannot appreciate how CBF varies across the complex landscape of the nasal vault and sinus tissues. With Spectrally encoded interferometric microscopy (SEIM), en face imaging of cilia can be achieved, providing insight into the changes in CBF across tissue surfaces. This study aims to validate the use of SEIM to quantify ciliary beat frequency across ex vivo upper airway tissue.

PurposeCorneal chemical injuries (CCI) obscure vision by opacifying the cornea; however, current treatments may not fully restore clarity. Here, we investigated potential-driven electrochemical treatment (P-ECT) to restore clarity after alkaline-based CCI in ex vivo rabbit corneas and examined collagen fiber orientation changes using second harmonic generation (SHG).MethodsNaOH was applied to the corneas of intact New Zealand white rabbit globes. P-ECT was performed on the opacified cornea while optical coherence tomography (OCT) imaging (∼35 frames per second) was simultaneously performed. SHG imaging evaluated collagen fiber structure before NaOH application and after P-ECT. Irrigation with water served as a control.ResultsP-ECT restored local optical clarity after NaOH exposure. OCT imaging shows both progression of NaOH injury and the restoration of clarity in real time. Analysis of SHG z-stack images show that collagen fibril orientation is similar between control, NaOH-damaged, and post-P-ECT corneas. NaOH-injured corneas flushed with water (15 minutes) show no restoration of clarity.ConclusionsP-ECT may be a means to correct alkaline CCI. Collagen fibril orientation does not change after NaOH exposure or P-ECT, suggesting that no irreversible matrix level fiber changes occur. Further studies are required to determine the mechanism for corneal clearing and to ascertain the optimal electrical dosimetry parameters and electrode designs.Translational relevanceOur findings suggest that P-ECT is a potentially effective, low-cost treatment for alkaline CCI.

Multiple light scattering is considered as the major limitation for deep imaging and focusing in turbid media. In this paper, we present an innovative method to overcome this limitation and enhance the delivery of light energy ultra-deep into turbid media with significant improvement in focusing. Our method is based on a wide-field reflection matrix optical coherence tomography (RM-OCT). The time-reversal decomposition of the RM is calibrated with the Tikhonov regularization parameter in order to get more accurate reversal results deep inside the scattering sample. We propose a concept named model energy matrix, which provides a direct mapping of light energy distribution inside the scattering sample. To the best of our knowledge, it is the first time that a method to measure and quantify the distribution of beam intensity inside a scattering sample is demonstrated. By employing the inversion of RM to find the matched wavefront and shaping with a phase-only spatial light modulator, we succeeded in both focusing a beam deep (~9.6 times of scattering mean free path, SMFP) inside the sample and increasing the delivery of light energy by an order of magnitude at an ultra-deep (~14.4 SMFP) position. This technique provides a powerful tool to understand the propagation of photon in a scattering medium and opens a new way to focus light inside biological tissues.

Intravascular polarization-sensitive optical coherence tomography (IV-PSOCT) provides depth-resolved tissue birefringence which can be used to evaluate the mechanical stability of a plaque. In our previous study, we reported a new strategy to construct polarization-sensitive optical coherence tomography in a microscope platform. Here, we demonstrated that this technology can be implemented in an endoscope platform, which has many clinical applications. A conventional intravascular OCT system can be modified for IV-PSOCT by introducing a 12-m polarization-maintaining fiber-based imaging probe. Its two polarization modes separately produce OCT images of polarization detection channels spatially distinguished by an image separation of 2.7 mm. We experimentally validated our IV-PSOCT with chicken tendon, chicken breast, and coronary artery as the image samples. We found that the birefringent properties can be successfully visualized by our IV-PSOCT.

In this paper, the terahertz (THz) absorption spectra of a nematic liquid crystal (NLC) cell are estimated via THz time-domain spectroscopy (TDS) using a mode-locked Yb-doped fiber laser as the pump source. The THz-TDS system is implemented by using a dipole antenna as an emitter and a bow tie antenna as a receiver. A THz emission bandwidth exceeding 2.2 THz is achieved corresponding to a free spacing of 220 mm and a signal-to-noise ratio exceeding 30 dB. Subsequently, this system was utilized to measure and analyze the THz absorption spectrum of an E7 NLC cell by applying an electric field. The conclusions experimentally confirmed that the absorption of the specific THz frequency of the cell is inversely proportional to the intensity of the electric field applied to the NLC cell.

Optical coherence tomography (OCT) is a non-invasive diagnostic method that offers real-time visualization of the layered architecture of the skin in vivo. The 1.7-micron OCT system has been applied in cardiology, gynecology and dermatology, demonstrating an improved penetration depth in contrast to conventional 1.3-micron OCT. To further extend the capability, we developed a 1.7-micron OCT/OCT angiography (OCTA) system that allows for visualization of both morphology and microvasculature in the deeper layers of the skin. Using this imaging system, we imaged human skin with different benign lesions and described the corresponding features of both structure and vasculature. The significantly improved imaging depth and additional functional information suggest that the 1.7-micron OCTA system has great potential to advance both dermatological clinical and research settings for characterization of benign and cancerous skin lesions.

SignificanceThe human vocal fold (VF) oscillates in multiple vectors and consists of distinct layers with varying viscoelastic properties that contribute to the mucosal wave. Office-based and operative laryngeal endoscopy are limited to diagnostic evaluation of the VF epithelial surface only and are restricted to axial-plane characterization of the horizontal mucosal wave. As such, understanding of the biomechanics of human VF motion remains limited.AimOptical coherence tomography (OCT) is a micrometer-resolution, high-speed endoscopic imaging modality which acquires cross-sectional images of tissue. Our study aimed to leverage OCT technology and develop quantitative methods for analyzing the anatomy and kinematics of in vivo VF motion in the coronal plane.ApproachA custom handheld laryngeal stage was used to capture OCT images with 800 A-lines at 250 Hz. Automated image postprocessing and analytical methods were developed.ResultsNovel kinematic analysis of in vivo, long-range OCT imaging of the vibrating VF in awake human subjects is reported. Cross-sectional, coronal-plane panoramic videos of the larynx during phonation are presented with three-dimensional videokymographic and space-time velocity analysis of VF motion.ConclusionsLong-range OCT with automated computational methods allows for cross-sectional dynamic laryngeal imaging and has the potential to broaden our understanding of human VF biomechanics and sound production.

Photoacoustic (PA) imaging is able to provide extremely high molecular contrast while maintaining the superior imaging depth of ultrasound (US) imaging. Conventional microscopic PA imaging has limited access to deeper tissue due to strong light scattering and attenuation. Endoscopic PA technology enables direct delivery of excitation light into the interior of a hollow organ or cavity of the body for functional and molecular PA imaging of target tissue. Various endoscopic PA probes have been developed for different applications, including the intravascular imaging of lipids in atherosclerotic plaque and endoscopic imaging of colon cancer. In this paper, the authors review representative probe configurations and corresponding preclinical applications. In addition, the potential challenges and future directions of endoscopic PA imaging are discussed.

Numerous techniques have been demonstrated for effective generation of orbital angular momentum-carrying radiation, but intracavity generation of continuously tunable pulses in the femtosecond regime remains challenging. Even if such a creation was realized, the generated pulses-like all pulses in reality-are complex and transitory objects that can only be comprehensively characterized via multidimensional spaces. An integrated lasing system that generates pulses while simultaneously quantifies them can achieve adaptive pulse tailoring. Here, we report a femtosecond pulse scope that unifies vector vortex mode-locked lasing and vectorial quantification. With intracavity-controlled Pancharatnam-Berry phase modulation, continuous and ergodic generation of spirally polarized states along a broadband higher-order Poincaré sphere was realized. By intrinsically coupling a two-dimensional polarization-sensitive time-scanning interferometer to the laser, multidimensional spatiotemporal features of the pulse were further visualized. The proposed methodology paves the way for design optimization of ultrafast optics by integrating complex femtosecond pulse generation and structural customization, facilitating its applications in optical physics research and laser-based manufacturing.

Recent advancements in the high-speed long-range optical coherence tomography (OCT) endoscopy allow characterization of tissue compliance in the upper airway, an indicator of collapsibility. However, the resolution and accuracy of localized tissue compliance measurement are currently limited by the lack of a reliable nonuniform rotational distortion (NURD) correction method. In this study, we developed a robust 2-step NURD correction algorithm that can be applied to the dynamic OCT images obtained during the compliance measurement. We demonstrated the utility of the NURD correction algorithm by characterizing the local compliance of nasopharynx from an awake human subject for the first time.

Acoustic radiation force optical coherence elastography (ARF-OCE) has been successfully implemented to characterize the biomechanical properties of soft tissues, such as the cornea and the retina, with high resolution using single-element ultrasonic transducers for ARF excitation. Most currently proposed OCE techniques, such as air puff and ARF, have less capability to control the spatiotemporal information of the induced region of deformation, resulting in limited accuracy and low temporal resolution of the shear wave elasticity imaging. In this study, we propose a new method called 2-D ultrasonic array-based OCE imaging, which combines the advantages of 3-D dynamic electronic steering of the 2-D ultrasonic array and high-resolution optical coherence tomography (OCT). The 3-D steering capability of the 2-D array was first validated using a hydrophone. Then, the combined 2-D ultrasonic array OCE system was calibrated using a homogenous phantom, followed by an experiment on ex vivo rabbit corneal tissue. The results demonstrate that our newly developed 2-D ultrasonic array-based OCE system has the capability to map tissue biomechanical properties accurately, and therefore, has the potential to be a vital diagnostic tool in ophthalmology.

PurposeTo evaluate endoscopic long-range optical coherence tomography system combined with a pressure sensor to concurrently measure internal nasal valve cross-sectional area and intraluminal pressure.MethodsA pressure sensor was constructed using an Arduino platform and calibrated using a limiter-controlled vacuum system and industrial absolute pressure gauge. Long-range optical coherence tomography imaging and pressure transduction were performed concurrently in the naris of eight healthy adult subjects during normal respiration and forced inspiration. The internal nasal valve was manually segmented using Mimics software and cross-sectional area was measured. Internal nasal valve cross-sectional area measurements were correlated with pressure recordings.ResultsMean cross-sectional area during forced inspiration was 6.49 mm2. The mean change in pressure between normal respiration and forceful inspiration was 12.27 mmHg. The direct correlation between pressure and cross-sectional area as measured by our proposed system was reproducible among subjects.ConclusionsOur results demonstrate a direct correlation between internal nasal valve cross-sectional area and nasal airflow during inspiration cycles. Endoscopic long-range optical coherence tomography coupled with a pressure sensor serves as a useful tool to quantify the dynamic behavior of the internal nasal valve.