This PDF file contains the front matter associated with SPIE Proceedings Volume 11627, including the Title Page, Copyright information, and Table of Contents.

Pathological alterations of the connective tissue, e.g. in succession of chronic otitis media, impair the acousto-mechanical function of the tympanic membrane (TM). Currently, none of the diagnostic techniques used in clinical practice assesses these tissue changes. By applying polarization-sensitive optical coherence tomography (PSOCT), a depth-resolved imaging technique providing additional tissue-specific contrast, local polarization changes of the fibrous layers of a human TM ex vivo were detected due to the birefringence of collagen fibers. Reconstructing and displaying local retardation from single-input PSOCT measurements enables to distinguish different tissue types which reveals the potential of PSOCT to extend conventional ENT diagnostics.

Sensorineural hearing loss (SNHL) is the most common sensory problem that causes permanent hearing loss due to the damage of cochlear hair cells. Current clinical imaging techniques do not provide sufficient resolution and functional assessment of the intracochlear structures. We developed a dual-mode endoscopic system that combines optical coherence tomography and autofluorescence to visualize the morphology and biochemical changes of the intracochlear structures. The preclinical assessment of the system was performed in a ovine model of SNHL in vivo. The preliminary results suggest that this approach may provide more accurate diagnosis of cochlear pathology and enable targeted SNHL therapies.

To date, there is still a lack of reliable imaging modalities to improve the quality of medical examinations of the oral mucosa in dentistry. One promising imaging technologies is optical coherence tomography (OCT). The present study provides in vivo intensity-based OCT cross sections of the human oral mucosa of the anterior and posterior oral cavity as well as the oropharynx of 47 disease-free adult volunteers. The randomized blinded image analysis was performed by means of 3,560 OCT cross sections using a set of seven qualitative and quantitative criteria to assess the epithelium and the lamina propria.

We successfully acquired a comprehensive three-dimensional imaging of swine Eustachian tubes using a catheter-based OCT. The OCT images clearly identified the structure and tissue components of the Eustachian tube, which was confirmed by the corresponding histological images. In addition, after the balloon dilation of the Eustachian tube, the OCT images clearly visualized the expanded luminal area of the Eustachian tube, quantitatively. The catheter-based OCT is expected to be applicable to the diagnosis and research of Eustachian tube disorder by providing real-time assessment.

Spectrally encoded interferometric microscopy (SEIM) is capable of detecting nanometer displacement at a frame rate in the kilohertz regime. By employing a wavelength-sweeping laser and a spectral disperser, SEIM can achieve en face imaging via one-axis scanning. In this study, we compared different processing algorithms for visualizing cilia-induced motion. Our Doppler-based method, combined with phase stabilization and bulk motion correction, provides the highest sensitivity for measuring ciliary beating frequency amongst the tested methods. Traveling waves induced by coordinated cilia motion were visualized. These results demonstrate the potential clinical utility of SEIM for monitoring respiratory function and therapeutic effects.

To non-invasively assess the impact of antibiotic therapy on otitis media (OM), a handheld OCT system was developed to longitudinally monitor in vivo middle ear conditions of OM-induced chinchilla models. The formation of middle ear effusions (MEEs) and biofilm were examined over the course of the infection. Furthermore, the effect of antibiotics on the biofilm as well as the amount and type of MEEs was investigated with low-dose and high-dose antibiotics (ceftriaxone). Quantitative parameters, such as TM thickness and effusion and biofilm scattering/texture, were correlated with histology and fluorescence in situ hybridization (FISH) at the end time point.

Middle ear effusions (MEEs) are accumulated middle ear secretions or fluid behind the eardrum during otitis media (OM). A portable, handheld OCT system was developed to non-invasively investigate various optical scattering properties of MEEs in pediatric subjects. Furthermore, clinically relevant parameters of MEEs, including viscosity and bacterial load, were measured from the extracted MEEs after the surgical procedure to treat OM. In vivo OCT images of the middle ear prior to the surgery, OCT images of the extracted MEEs, and biological parameters were correlated to determine the relationship between the optical signatures in MEEs and the clinical findings of OM.

For specific indications in neurosurgery, such as the removal of brain tumors in eloquent locations and the deep brain stimulation, awake craniotomy offers multiple advantages. However, due to the severe discomfort experienced during burr-hole drilling, patients are hesitant to opt for awake craniotomy. Laser systems provide an alternative to surgical drills as a silent and vibration-free bone cutting method. Until now no laser system achieved adequate ablation rates (> 2:5mm³/s) at sufficiently high aspect ratio (>5) to fulfill the requirements for craniotomy. The aim of this study is to investigate the ablation of bone tissue under the needs for neurosurgery using three different Q-switched infrared laser sources assisted by a water spray system. One of the laser sources is a commercial Q-switched CO₂ laser system operating at 10:6 μm with a pulse energy of 4 mJ. In addition, two in-house developed, short-pulsed IR-laser sources operating at 2:91 μm (Cr:ZnSe) with a pulse energy of 0:76mJ and at 1:9 μm (Tm:YLF) with a pulse energy of 2:2mJ are investigated. The results show that highly efficient bone ablation with the CO₂ laser at rates of 6mm³/s is possible without carbonization. With an ablation strategy using the effect of multiple reflections inside the kerf an aspect ratio of 17 was achieved for narrow incisions at widths smaller than 100 μm. Another ablation strategy shows a twofold higher ablation depth shifting the laser focus stepwise into propagation direction. Even though a high ablation efficiency can be achieved with the Cr:ZnSe laser source and the CO2 laser source, the Cr:ZnSe laser cannot fulfill the required ablation rates. The CO₂ laser shows a fast ablation in significant depth with a maximum depth of 7 mm. Further investigations will concentrate on increasing the ablation depth to 10 mm.

Since tumor doubling time of head and neck squamous cell carcinoma (HNSCC) is on the order of 100 days, prescribing the most effective treatment for HNSCC patients is of great benefit to the patients. In this work, we describe the use of precisely cut tumor slices on the order of 200 mm in thickness for testing the effect of chemotherapy drugs. Both spectroscopic and microscopic imaging were used to analyze treatment efficacy. Overall, viability of tumor slices decreases with increased drug concentration although within the same patient, drug response varies among different tumor slices. With additional development, this approach may be used to predict treatment of chemotherapy and immunotherapy response for personalized medicine.

At the present, identifying head and neck squamous cell carcinoma (HNSCC) patients for immune checkpoint inhibitor therapy (ICIT) is achieved through the determination of Tumor Proportion Score (TPS) or the percentage of tumor cells positively labeled for PD-L1. Estimation of TPS is largely done in a manual fashion by a trained pathologist. In the case of HNSCC, the histological section can be over 1 cm in size in which over 100,000 cancer cells need to be evaluated for PD-L1 expression. To expedite the TPS evaluation process for such large specimens, we have developed a platform in which artificial intelligence (AI) is used for TPS determination. With additional development, this approach may be used in the clinical setting to assist pathologists in TPS evaluation.

The objective of this randomized, split-mouth controlled, clinical trial was to evaluate whether the use of a short-pulsed 9.3µm CO2-laser increases the caries resistance of occlusal pit and fissures in addition to fluoride therapy over 12-months. 60 participants were enrolled. Second molars were randomized into test and control. Test molars were irradiated with a 9.3μm CO2-laser. Test molars received laser and fluoride treatment, control teeth fluoride alone. 57 participants completed the 6-month, 51 the 12-month recall. Laser treated surfaces showed very slight ICDAS improvements. Control teeth showed significantly higher ICDAS increases. Differences in ICDAS-changes between the groups were statistically significant. A total of 22% of the participants developed ICDAS-3 scores on the control teeth. Microsecond short-pulsed 9.3µm CO2-laser irradiation markedly inhibits caries progression in pits and fissures in comparison to fluoride varnish alone.

An optical coherence tomography (OCT) system with a prototype dental probe was used to image fresh, frozen porcine jaws to evaluate the ability to identify different tissue types in the periodontium. OCT reliably imaged structures in the tooth and the periodontium to optical depths of approximately 3 mm at the 18 swine premolar sites measured. Measurements of the cemento-enamel junction (CEJ) to alveolar crest (AC) distance with OCT were compared to microphotography measurements at matching anatomic sites. Strong correlation between the measurements was observed (Person correlation r=0.89). Bland-Altman analysis of the agreement between measurements showed good agreement, no systematic bias, and zero fixed bias (p<0.01). This pilot study suggests OCT may be used to optically, non-invasively monitor periodontal conditions, in particular changes in alveolar bone level as measured by the CEJ-AC distance, in real time.

Measuring the activity of oral-bacteria in plaque, the sticky biofilm on enamel, can provide the presently lacking oral feedback to patients. We have developed O-pH, optical pH monitor that measures pH in the range of 4-7.5 and tested in vivo on 25 pediatric subjects (10-18 years) with high caries risk, 18 of these subjects had a dental cleaning within last two months and 7 didn’t have a cleaning in over 2 months. The average pH after a sugar rinse from regions of biofilm associated with caries was 5.8 and 0.5 units lower than the biofilm of sound enamel.

Intraoral imaging of teeth with near-IR light provides increased contrast of dental caries and restorative materials compared to visible inspection and digital radiography. The objective of this study was to investigate the near-IR optical properties of the dental pulp-chamber floor, walls and canal orifices. We imaged in vitro extracted human posterior teeth at 1300-nm and 1500-1700-nm in reflectance and transillumination and compared the tissues properties with visible light images and quantitative light fluorescence. Transillumination of posterior teeth at both 1300-nm and 1500-1700-nm yielded significantly higher contrast between the pulp-chamber floor and walls than all other methods.

This study investigated the utility of using OCT to monitor SDF application over time. Twenty dentin blocks each with 5 windows were exposed to a demineralization solution to produce carious lesions. Treatment windows included sound, sound+SDF, lesion, lesion+SDF, lesion+SDF+SDF. Lesion depth, mean reflectivity over the lesion depth and optical penetration through the lesions were monitored with OCT for 12 weeks. OCT was able to show changes in the reflectivity and optical penetration in demineralized and sound dentin after SDF application over time. Such changes can potentially be monitored to determine if and when re-application of SDF is needed.

We have developed a clinical probe capable of acquiring simultaneous short wavelength infrared (SWIR) cross-polarized reflectance and occlusal transillumination images of lesions on tooth proximal and occlusal surfaces. We hypothesize that the dual SWIR reflectance and transillumination probe will improve the diagnostic accuracy of the device by reducing false positives since it is unlikely that confounding structural features or specular reflection are going to be present in both reflectance and transillumination images. In addition, the dual probe will provide complementary diagnostic information about lesion severity to help discriminate early superficial lesions on tooth surfaces from deeply penetrating lesions. The dual probe was 3D printed and equipped with a compact InGaAs camera and broadband superluminescent diode light sources that emit broadband light at 1300 nm for occlusal transillumination and 1600 nm light for cross-polarization reflectance measurements. The first clinical images acquired using this novel probe are presented.

Several studies have demonstrated the potential of short wavelength infrared (SWIR) reflectance, thermal imaging and optical coherence tomography for the nondestructive assessment of the activity of caries lesions. The purpose of this study was to test the hypothesis that the activity of arrested caries lesions on the coronal surfaces of extracted teeth would be changed by reducing the thickness of the highly mineralized transparent surface layer, which was measured using polarization sensitive optical coherence tomography (PS-OCT). The lesion activity was assessed using SWIR reflectance and thermal imaging during forced air drying of the lesion before and after mechanical removal of a surface layer ~ 50-μm thick covering the lesion. Both the intensity change in SWIR reflectance images at 1500- 1750-nm wavelengths after drying the lesions and the change in thermal emission measured with a thermal camera at 8-13-μm wavelengths increased significantly (P<0.05) after reducing the thickness of the mineralized surface layer in the lesions indicating the permeability of the lesion to fluids increased. These results provide further evidence that the presence of a highly mineralized outer surface layer is a key indicator of lesion arrest.

Changes in the reflectivity of lesions on the proximal surfaces of extracted human teeth were measured at 1500-2340-nm and at 1950-nm as they were dried with air. An extended range tungsten-halogen lamp with a long pass filter (1500-2340-nm) and a broadband ASE source centered near the peak of the water-absorption band at 1950-nm were used as light sources and an extended range InGaAs camera (1000-2340-nm) was used to acquire reflected light images as the samples were dried with air. SWIR light at 1950-nm yields extremely high contrast of demineralization and appears to be the optimum wavelength for the assessment of lesion activity on tooth coronal surfaces.

Dental fluorosis is an increasing problem in the U.S. due to excessive exposure to fluoride from the environment. Fluorosis causes hypomineralization of the enamel during tooth development and mild fluorosis is visible as faint white lines on the tooth surface while the most severe fluorosis can result in pitted surfaces. It is difficult to quantify the severity of fluorosis and assessments are limited to subjective visual assessments. Dental fluorosis appears with very high contrast at short wavelength infrared (SWIR) wavelengths beyond 1400-nm and we hypothesize that these wavelengths may be better suited for detecting mild fluorosis and for estimating the severity. In this study the contrast of fluorosis of varying severity on extracted human permanent teeth was measured at SWIR wavelengths ranging from 1300-2000-nm using an extended range InGaAs camera and broadband light sources. Cross polarization optical coherence tomography was used to measure the depth of hypomineralization.