This PDF file contains the front matter associated with SPIE Proceedings Volume 10039, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

Background and Objective: Noninvasive middle and inner ear imaging using optical coherence tomography (OCT) presents some unique challenges for real-time, clinical use in animals and humans. The goal of this study was to investigate whether OCT provides information about the middle and inner ear microstructures by examining extratympanic structures. Materials and Methods: Five mice and rats were included in the experiment, and the swept-source OCT system was tested to identify the middle and inner ear microstructures and to measure the length or thickness of various structures. Results: It was possible to see middle ear structures through the tympanic membrane with the OCT instrument located extratympanically in both rats and mice. We could also obtain the inner ear images through the otic capsule in the mice, but the bulla needed to be removed to visualize the inner ear structures in the rats. The whole apical, middle and basals of the cochlea and the thickness of the otic capsule covering the cochlea could be visualized simultaneously. Conclusions: OCT is a promising technology to assess middle ear and inner ear microanatomy noninvasively in both mice and rats. OCT imaging could provide additional diagnostic information about the diseases of the middle and inner ear.

In this study, we monitored the optical clearing effects by immersing ex vivo guinea pig cochlea samples in ethylenediaminetetraacetic acid (EDTA) to study the internal microstructures in the morphology of guinea pig cochlea. The imaging limitations due to the guinea pig cochlea structures were overcome by optical clearing technique. Subsequently, the study was carried out to confirm the required approximate immersing duration of cochlea in EDTA-based optical clearing to obtain the best optimal depth visibility for guinea pig cochlea samples. Thus, we implemented a decalcification-based optical clearing effect to guinea pig cochlea samples to enhance the depth visualization of internal microstructures using swept source optical coherence tomography (OCT). The obtained nondestructive two-dimensional OCT images successfully illustrated the feasibility of the proposed method by providing clearly visible microstructures in the depth direction as a result of decalcification. The most optimal clearing outcomes for the guinea pig cochlea were obtained after 14 consecutive days. The quantitative assessment results verified the increase of the intensity as well as the thickness measurements of the internal microstructures. Following this method, difficulties in imaging of internal cochlea microstructures of guinea pigs could be avoided. The obtained results verified that the depth visibility of the decalcified ex vivo guinea pig cochlea samples was enhanced. Therefore, the proposed EDTA-based optical clearing method for guinea pig can be considered as a potential application for depth-enhanced OCT visualization.

Sensorineural hearing loss (SNHL), which typically originates in the cochlea, is the most common otologic problem caused by aging and noise trauma. The cochlea, a delicate and complex biological mechanosensory transducer in the inner ear, has been extensively studied with the goal of improving diagnosis of SNHL. However, the difficulty associated with accessing the cochlea and resolving the microstructures that facilitate hearing within it in a minimally-invasive way has prevented us from being able to assess the pathology underlying SNHL in humans. To address this problem we investigated the ability of a multimodal optical system that combines optical coherence tomography (OCT) and single photon autofluorescence imaging (AFI) to enable visualization and evaluation of microstructures in the cochlea. A laboratory OCT/AFI imager was built to acquire high resolution OCT and single photon fluorescence images of the cochlea. The imager’s ability to resolve diagnostically-relevant details was evaluated in ears extracted from normal and noise-exposed mice. A prototype endoscopic OCT/AFI imager was developed based on a double-clad fiber approach. Our measurements show that the multimodal OCT/AFI imager can be used to evaluate structural integrity in the mouse cochlea. Therefore, we believe that this technology is promising as a potential clinical evaluation tool, and as a technique for guiding otologic surgeries such as cochlear implant surgery.

We describe a novel, multi-modal imaging protocol for validating quantitative dynamic airway imaging performed using anatomical Optical Coherence Tomography (aOCT). The aOCT system consists of a catheter-based aOCT probe that is deployed via a bronchoscope, while a programmable ventilator is used to control airway pressure. This setup is employed on the bed of a Siemens Biograph CT system capable of performing respiratory-gated acquisitions. In this arrangement the position of the aOCT catheter may be visualized with CT to aid in co-registration. Utilizing this setup we investigate multiple respiratory pressure parameters with aOCT, and respiratory-gated CT, on both ex vivo porcine trachea and live, anesthetized pigs. This acquisition protocol has enabled real-time measurement of airway deformation with simultaneous measurement of pressure under physiologically relevant static and dynamic conditions- inspiratory peak or peak positive airway pressures of 10-40 cm H₂O, and 20-30 breaths per minute for dynamic studies. We subsequently compare the airway cross sectional areas (CSA) obtained from aOCT and CT, including the change in CSA at different stages of the breathing cycle for dynamic studies, and the CSA at different peak positive airway pressures for static studies. This approach has allowed us to improve our acquisition methodology and to validate aOCT measurements of the dynamic airway for the first time. We believe that this protocol will prove invaluable for aOCT system development and greatly facilitate translation of OCT systems for airway imaging into the clinical setting.

Ventilation, speech and singing must use facial musculature to complete these motor tasks and these tasks are fueled by the air we inhale. This motor process requires increase in the blood flow as the muscles contract and relax, therefore skin surface temperature changes are expected. Hence, we used thermography to image these effects. The system used was the thermography camera model FLIR X6580sc with a chilled detector (FLIR Systems Advanced Thermal Solutions, 27700 SW Parkway Ave Wilsonville, OR 97070, USA). To assure improved imaging, the room temperature was air-conditioned to +18° C. All images were recoded at the speed of 30 f/s. Acquired data were analyzed with FLIR Research IR Max Version 4 software and software filters. In this preliminary study a male subject was imaged from frontal and lateral views simultaneously while he performed normal resting ventilation, speech and song. The lateral image was captured in a stainless steel mirror. Results showed different levels of heat flow in the facial musculature as a function of these three tasks. Also, we were able to capture the exalted air jet directionality. The breathing jet was discharged in horizontal direction, speaking voice jet was discharged downwards while singing jet went upward. We interpreted these jet directions as representing different gas content of air expired during these different tasks, with speech having less oxygen than singing. Further studies examining gas exchange during various forms of speech and song and emotional states are warranted.

We used HSDP (KayPENTAX Model 9710, NJ, USA) to capture the kinematics of vocal folds in the production of extreme vocalization used by heavy metal performers. The vibrations of the VF were captured at 4000 f/s using transoral rigid scope. Growl, scream and inhalatory phonations were recoded. Results showed that these extreme sounds are produced predominantly by supraglottic tissues rather than by the true vocal folds, which explains while these sounds do not injure the mucosa of the true vocal folds. In addition, the HSDI were processed using custom software (Vocalizer®) that clearly demonstrated the contribution of each vocal fold to the generation of the sound.

Growl, a style of extreme vocalization used for the production of bizarre and scary voice by heavy metal singes captured by HSDP is simply fascinating and shows that this sound is produced predominantly by the supraglottic structures. To enhance our understanding of how this process is accomplished. The obtained images were processed to be viewed in 3-D. The results are shown and discussed.

Amyloidosis is an unknown pathogenic process in which abnormally folded proteins are deposited in the extracellular space as macroscopic aggregates. Laryngeal deposits of these proteins are extremely rare, but primarily cause dysphonia in patients. High Speed Digital Phonoscopy (HSDP) was used to capture the kinematics of vocal folds in a patient with laryngeal amyloidosis. Acoustic data was also recorded and both HSDP and acoustics were processed using custom Vocalizer® software to help elucidate the physiological impact of amyloids in the larynx, especially in regards to effects on the voice.

This ex vivo study evaluates the feasibility of diffuse reflectance spectroscopy (DRS) for discriminating tumor from healthy oral tissue, with the aim to develop a technique that can be used to determine a complete excision of tumor through intraoperative margin assessment. DRS spectra were acquired on fresh surgical specimens from patients with an oral squamous cell carcinoma. The spectra represent a measure of diffuse light reflectance (wavelength range of 400-1600 nm), detected after illuminating tissue with a source fiber at 1.0 and 2.0 mm distances from a detection fiber. Spectra were obtained from 23 locations of tumor tissue and 16 locations of healthy muscle tissue. Biopsies were taken from all measured locations to facilitate an optimal correlation between spectra and pathological information. The area under the spectrum was used as a parameter to classify spectra of tumor and healthy tissue. Next, a receiver operating characteristics (ROC) analysis was performed to provide the area under the receiver operating curve (AUROC) as a measure for discriminative power. The area under the spectrum between 650 and 750 nm was used in the ROC analysis and provided AUROC values of 0.99 and 0.97, for distances of 1 mm and 2 mm between source and detector fiber, respectively. DRS can discriminate tumor from healthy oral tissue in an ex vivo setting. More specimens are needed to further evaluate this technique with component analyses and classification methods, prior to in vivo patient measurements.

Autofluorescence lifetime spectroscopy is a promising non-invasive label-free tool for characterization of biological tissues and shows potential to report structural and biochemical alterations in tissue owing to pathological transformations. In particular, when combined with fiber-optic based instruments, autofluorescence lifetime measurements can enhance intraoperative diagnosis and provide guidance in surgical procedures. We investigate the potential of a fiber-optic based multi-spectral time-resolved fluorescence spectroscopy instrument to characterize the autofluorescence fingerprint associated with histologic, morphologic and metabolic changes in tissue that can provide real-time contrast between healthy and tumor regions in vivo and guide clinicians during resection of diseased areas during transoral robotic surgery. To provide immediate feedback to the surgeons, we employ tracking of an aiming beam that co-registers our point measurements with the robot camera images and allows visualization of the surgical area augmented with autofluorescence lifetime data in the surgeon’s console in real-time. For each patient, autofluorescence lifetime measurements were acquired from normal, diseased and surgically altered tissue, both in vivo (pre- and post-resection) and ex vivo. Initial results indicate tumor and normal regions can be distinguished based on changes in lifetime parameters measured in vivo, when the tumor is located superficially. In particular, results show that autofluorescence lifetime of tumor is shorter than that of normal tissue (p < 0.05, n = 3). If clinical diagnostic efficacy is demonstrated throughout this on-going study, we believe that this method has the potential to become a valuable tool for real-time intraoperative diagnosis and guidance during transoral robot assisted cancer removal interventions.

A relatively wide field-of-view and high resolution imaging is necessary for navigating the scope within the body, inspecting tissue, diagnosing disease, and guiding surgical interventions. As the large number of modes available in the multimode fibers (MMF) provides higher resolution, MMFs could replace the millimeters-thick bundles of fibers and lenses currently used in endoscopes. However, attributes of body fluids and obscurants such as blood, impose perennial limitations on resolution and reliability of optical imaging inside human body. To design and evaluate optimum imaging techniques that operate under realistic body fluids conditions, a good understanding of the channel (medium) behavior is necessary. In most prior works, Monte-Carlo Ray Tracing (MCRT) algorithm has been used to analyze the channel behavior. This task is quite numerically intensive. The focus of this paper is on investigating the possibility of simplifying this task by a direct extraction of state transition matrices associated with standard Markov modeling from the MCRT computer simulations programs. We show that by tracing a photon’s trajectory in the body fluids via a Markov chain model, the angular distribution can be calculated by simple matrix multiplications. We also demonstrate that the new approach produces result that are close to those obtained by MCRT and other known methods. Furthermore, considering the fact that angular, spatial, and temporal distributions of energy are inter-related, mixing time of Monte- Carlo Markov Chain (MCMC) for different types of liquid concentrations is calculated based on Eigen-analysis of the state transition matrix and possibility of imaging in scattering media are investigated. To this end, we have started to characterize the body fluids that reduce the resolution of imaging [1].

Worldwide, there are over 450,000 new cases of oral cancer reported each year. Late-stage diagnosis remains a significant factor responsible for its high mortality rate (>50%). In-vivo non-invasive rapid imaging techniques, that can visualise clinically significant changes in the oral mucosa, may improve the management of oral cancer. We present an analysis of features extracted from oral images obtained using our hand- held wide-field Optical Coherence Tomography (OCT) instrument. The images were analyzed for epithelial scattering, overall tissue scattering, and 3D basement membrane topology. The associations between these three features and disease state (benign, pre-cancer, or cancer), as measured by clinical assessment or pathology, were determined. While scattering coefficient has previously been shown to be sensitive to cancer and dysplasia, likely due to changes in nuclear and cellular density, the addition of basement membrane topology may increase diagnostic ability- as it is known that the presence of bulbous rete pegs in the basement membrane are characteristic of dysplasia. The resolution and field-of-view of our oral OCT system allowed analysis of these features over large areas of up to 2.5mm x 90mm, in a timely fashion, which allow for application in clinical settings.

Radiation therapy (RT) can promote anti-tumoral responses, but is also known to cause lymphatic endothelial cell apoptosis, loss of dermal lymphatics, and reduction in lymph transport to draining lymph node basins. When combined with lymph node dissection (LND), the radiogenic lymphatic disruption may possibly result in lymph stasis and dermal backflow. If not resolved, this disruption may lead to chronic inflammation, edema, fibrosis, adipose tissue deposition, and ultimately to functional deficits and disfigurement. Because the head and neck (HN) region contains 1/3 of the body’s lymph nodes, lymphatic responses to cancer progression and therapy may be significant. Furthermore, it may not be surprising that lymphedema has been estimated to impact as many as 75% of HN cancer survivors three months or more after LND and RT. In this study, we used near-infrared fluorescence imaging to longitudinally assess the lymphatics of 18 patients undergoing treatment for cancer of the oral cavity, oropharynx, and/or larynx following intraoral and intradermal injections of ICG. Patients were imaged before and after surgery, before and after fractionated RT for up to 100 weeks after treatments. Patients who underwent both LND and RT developed lymphatic dermal backflow on treated sides ranging from days after the start of RT to weeks after its completion, while contralateral regions that were not associated with LND but also treated with RT, experienced no such changes in functional lymphatic anatomies. The results show for the first time, the striking reorganization of the lymphatic vasculature and may enable early diagnosis of HN lymphedema.

A “green” laser (e.g. Nd:YAG, λ = 532 nm) together with the red dye Rose Bengal (RB) have been used for photochemical tissue bonding (PTB). It has been reported that irradiation of RB with light at 532 nm produces free radicals. For tissue bonding with a Nd:YAG laser it has been proposed that the free radicals than crosslink the tissue collagen and lead to the closing of the surgical incisions. RB is also a red solution and it is possible that RB absorbs the photons delivered from the laser and converts them into heat with a measurable local temperature increase. It is possible that the mechanism for PTB is not only caused by free radical formation but also by a temperature increase in the tissue. In the present study we measured the local tissue temperature with a micro thermometer during irradiation with a Nd:YAG laser before and after RB was applied. For the present laser settings “tissue painting” with RB lead to a temperature increase resulting in tissue coagulation and charring. PTB was also studied for RB with a free radical scavenger, vitamin C. No significant difference in bonding strength was found for RB alone and for RB together with a free radical scavenger. In case no RB was applied no tissue bonding occurred. Bonding strength was quantified using the leakage seal test

As cartilage is an ideal natural material for transplantation, its use in the ENT surgery is limited by a difficulty to get proper shape of cartilage implants. Aim of the work is to make ring-shaped cartilage implants, to check their stability after laser reshaping and to perform transplantation into rabbits in vivo. We experimented with costal cartilages of 1-2 mm in thickness obtained from 3rd and 4rd ribs of a rabbit. 1.56 μm laser (Arcuo Medical Inc.) was used for cartilage reshaping. The laser settings were established taking into account anisotropy of cartilage structure for different orientation of the implants. The reshaped cartilage implants were surgically sewn to rib cartilages of the other rabbits. The rabbits were slaughtered in 3.5-4 months after surgery. The results have shown that (1) all reshaped implants kept circular form, and (2) the implants were adhered to the native rabbit cartilage sites (3) pronounced signs of regeneration in the intermediate zones were observed. The prospects of the cartilage implants use in larynx stenosis surgery are discussed.