Using attenuation coefficients from optical coherence tomography as markers of vocal fold maturation

Genetics and voice production in childhood and adolescence - a review

Adolescence is a challenging time of change in voicing, normally and in pathology. An increased focus on voice production in relation to genetics can expand our knowledge of the onset of puberty and voice change. Our aim with this review was to connect research of genetics to voice production in adolescence. We need further understanding of the developmental background of voice in childhood and adolescence, because many genetic multi handicaps include voice production. Genetic development related to voice production was the focus in a search made by the Royal English Society of Medicine, with only a few results. We supplemented with references to genetic studies of adults and animals as well as adjacent areas of voice production. The genetic development of voice production is steered from the hypothalamus probably related to growth hormone. The genetic voice production in adults form the basis for understanding development. Some research results were found related to the pubertal steps. The findings are important in the future, using advanced voice analysis and artificial intelligence methods in patients with Multi handicaps.

Surface kinematic and depth-resolved analysis of human vocal folds in vivo during phonation using optical coherence tomography

SIGNIFICANCE

The 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.

AIM

Optical 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.

APPROACH

A 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.

RESULTS

Novel 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.

CONCLUSIONS

Long-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.

Quantitative evaluation of the human vocal fold extracellular matrix using multiphoton microscopy and optical coherence tomography

Identifying distinct normal extracellular matrix (ECM) features from pathology is of the upmost clinical importance for laryngeal diagnostics and therapy. Despite remarkable histological contributions, our understanding of the vocal fold (VF) physiology remains murky. The emerging field of non-invasive 3D optical imaging may be well-suited to unravel the complexity of the VF microanatomy. This study focused on characterizing the entire VF ECM in length and depth with optical imaging. A quantitative morphometric evaluation of the human vocal fold lamina propria using two-photon excitation fluorescence (TPEF), second harmonic generation (SHG), and optical coherence tomography (OCT) was investigated. Fibrillar morphological features, such as fiber diameter, orientation, anisotropy, waviness and second-order statistics features were evaluated and compared according to their spatial distribution. The evidence acquired in this study suggests that the VF ECM is not a strict discrete three-layer structure as traditionally described but instead a continuous assembly of different fibrillar arrangement anchored by predominant collagen transitions zones. We demonstrated that the ECM composition is distinct and markedly thinned in the anterior one-third of itself, which may play a role in the development of some laryngeal diseases. We further examined and extracted the relationship between OCT and multiphoton imaging, promoting correspondences that could lead to accurate 3D mapping of the VF architecture in real-time during phonosurgeries. As miniaturization of optical probes is consistently improving, a clinical translation of OCT imaging and multiphoton imaging, with valuable qualitative and quantitative features, may have significant implications for treating voice disorders.

Extratympanic Observation of Middle and Inner Ear Structures in Rodents Using Optical Coherence Tomography

Objectives

This study aimed to investigate whether optical coherence tomography (OCT) provides useful information about the microstructures of the middle and inner ear via extratympanic approach and thereby could be utilized as an alternative diagnostic technology in ear imaging.

Methods

Five rats and mice were included, and the swept-source OCT system was applied to confirm the extent of visibility of the middle and inner ear and measure the length or thickness of the microstructures in the ear. The cochlea was subsequently dissected following OCT and histologically evaluated to compare with the OCT images.

Results

The middle ear microstructures such as ossicles, stapedial artery and oval window through the tympanic membrane with the OCT could be confirmed in both rats and mice. It was also possible to obtain the inner ear images such as each compartment of the cochlea in the mice, but the bone covering bulla needed to be removed to visualize the inner ear structures in the rats which had thicker bulla. The bony thickness covering the cochlea could be measured, which showed no significant differences between OCT and histologic image at all turns of cochlea.

Conclusion

OCT has been shown a promising technology to assess real-time middle and inner ear microstructures noninvasively with a high-resolution in the animal model. Therefore, OCT could be utilized to provide additional diagnostic information about the diseases of the middle and inner ear.

Utility of Optical Coherence Tomography for Guiding Laser Therapy Among Patients With Recurrent Respiratory Papillomatosis

Importance

Recurrent respiratory papillomatosis (RRP) is a viral-induced disease caused by human papillomavirus and the second leading cause of dysphonia in children; however, neither a cure nor a definitive surgical treatment is currently available for RRP. Although laser therapy is often used in the treatment of RRP, the lack of real-time laser-tissue interaction feedback undermines the ability of physicians to provide treatments with low morbidity. Therefore, an intraoperative tool to monitor and control laser treatment depth is needed.

Objective

To investigate the potential of combining optical coherence tomography (OCT) with laser therapy for patient-tailored laryngeal RRP treatments.

Design, Setting, and Participants

This in vivo study was performed at the Massachusetts Eye and Ear Infirmary from February 1, 2017, to September 1, 2017. Three-dimensional OCT images were acquired before, during, and after photoangiolytic laser therapy in 10 pediatric patients with a history of papilloma growth who presented with lesions and hoarseness.

Main Outcomes and Measures

Whether intraoperative OCT monitoring of changes in optical scattering and absorption provides quantitative information to control thermal damage in tissue.

Results

Among the 10 pediatric patients (age range, 4-11 years; 6 male) included in the study, high-resolution OCT images revealed epithelial hyperplasia with clear RRP lesion margins. Images acquired during therapy indicated coagulation deep in tissue, and posttherapy images showed the ability to quantify the amount of tissue ablated by the photoangiolytic laser.

Conclusions and Relevance

Concurrent use of OCT imaging and laser therapy may improve postoperative outcomes for patients with RRP by delivering an optimal, patient-tailored treatment. Additional studies investigating the correlation between optical properties with vocal outcomes are required.

Using intraoperative optical coherence tomography to image pediatric unilateral vocal fold paralysis

OBJECTIVES

Unilateral vocal fold paralysis (UVFP) impairs communication and reduces academic performance and social interactions in children. Deciding between temporary, permanent, or potentially destructive surgical interventions can be challenging, as there currently exists no reliable means of predicting vocal fold recovery or assessing the presence of vocal fold atrophy. Regarding vocal fold atrophy, optical coherence tomography (OCT) has been shown to be an appealing non-invasive alternative for accessing vocal fold structures. This study describes UVFP microanatomy and identifies possible vocal fold atrophy using OCT.

METHODS

Three UVFP patients (ages 1, 11, and 17 years) underwent bilateral OCT imaging using a handheld probe while under general anesthesia for direct laryngoscopy, and the laryngoscopic images were compared with images obtained from OCT. Structural morphological features were extracted and compared to a healthy patients' cohort.

RESULTS

While endoscopy showed no evidence of vocal fold atrophy in two of three cases, OCT images revealed distinct differences between the lamina propria of the paralyzed and functional vocal folds in all patients. In two cases, the paralyzed vocal fold morphology was similar to a healthy patient at the age of nerve injury. The third case exhibited extensive scarring in the lamina propria of the paralyzed vocal fold.

CONCLUSION

This pilot study characterizes and compares vocal fold microanatomy in three UVFP patients. In most cases, lamina propria development halted at the age of paralysis, suggesting that lamina propria maturation may be dependent on vocal fold functionality. OCT shows potential to aid UVFP assessment and treatment decisions by evaluating the presence of atrophy.

Clinical and surgical implications of intraoperative optical coherence tomography imaging for benign pediatric vocal fold lesions

INTRODUCTION

Benign vocal disorders in children include an extensive list of abnormalities creating a variety of debilitating levels of dysphonia. Precise delineation of the benign lesion type and margins may have significant public health implications in children. An innovative technology such as optical coherence tomography (OCT) is being explored to delineate pediatric benign laryngeal lesions. An accurate assessment of the subepithelial morphology may help towards tailoring more personalized therapeutic treatments. This study was established to highlight key morphological and optical features of benign pediatric laryngeal lesions using intraoperative OCT and to suggest clinical implications that arise from such optical imaging.

METHODS AND MATERIALS

This in vivo study was performed at Massachusetts Eye and Ear Infirmary. Intraoperative imaging was performed on twenty-five pediatric patients ranging from 1 year to 16 years of age presenting hoarseness. Three-dimensional OCT images of benign laryngeal lesions or a subsite of the lesion were acquired.

RESULTS

High-resolution OCT images of 25 patients with benign laryngeal lesions such as nodules, cysts, Reinke's edema, vocalis sulcus, and papilloma revealed distinct and specific morphological differences with normal tissue. Nodules show a symmetrical superficial remodeling of the vocal fold epithelial layer and the basement membrane. Cysts have oval-like shape and are either superficial or deeply located in the lamina propria. Sulcus vocalis OCT imaging allows characterizing if the lesion is shallow or deep according to Ford's classification system. Reinke's edema of the mucosa can be observed and quantified, which may lead to suspicion on the underlying social and medical conditions. Finally, the ability to assess margins and depth of invasion of papilloma lesions is demonstrated, raising the possibility to use OCT with angiolytic lasers for patient-tailored treatments.

CONCLUSIONS

OCT imaging of benign pediatric vocal lesions is promising as it could improve preoperative decision-making and possibly peroperative imaging-guidance for patient-tailored treatments. An assessment of the optical contrast between healthy and abnormal tissue may help towards a more qualitative and quantitative approach to current standard care, especially when diagnosis remains unclear.

Endoscopic optical coherence tomography: technologies and clinical applications [Invited]

In this paper, we review the current state of technology development and clinical applications of endoscopic optical coherence tomography (OCT). Key design and engineering considerations are discussed for most OCT endoscopes, including side-viewing and forward-viewing probes, along with different scanning mechanisms (proximal-scanning versus distal-scanning). Multi-modal endoscopes that integrate OCT with other imaging modalities are also discussed. The review of clinical applications of endoscopic OCT focuses heavily on diagnosis of diseases and guidance of interventions. Representative applications in several organ systems are presented, such as in the cardiovascular, digestive, respiratory, and reproductive systems. A brief outlook of the field of endoscopic OCT is also discussed.

Collagen Content Limits Optical Coherence Tomography Image Depth in Porcine Vocal Fold Tissue

OBJECTIVE

Vocal fold scarring, a condition defined by increased collagen content, is challenging to treat without a method of noninvasively assessing vocal fold structure in vivo. The goal of this study was to observe the effects of vocal fold collagen content on optical coherence tomography imaging to develop a quantifiable marker of disease.

STUDY DESIGN

Excised specimen study.

SETTING

Massachusetts Eye and Ear Infirmary.

SUBJECTS AND METHODS

Porcine vocal folds were injected with collagenase to remove collagen from the lamina propria. Optical coherence tomography imaging was performed preinjection and at 0, 45, 90, and 180 minutes postinjection. Mean pixel intensity (or image brightness) was extracted from images of collagenase- and control-treated hemilarynges. Texture analysis of the lamina propria at each injection site was performed to extract image contrast. Two-factor repeated measure analysis of variance and t tests were used to determine statistical significance. Picrosirius red staining was performed to confirm collagenase activity.

RESULTS

Mean pixel intensity was higher at injection sites of collagenase-treated vocal folds than control vocal folds (P < .0001). Fold change in image contrast was significantly increased in collagenase-treated vocal folds than control vocal folds (P = .002). Picrosirius red staining in control specimens revealed collagen fibrils most prominent in the subepithelium and above the thyroarytenoid muscle. Specimens treated with collagenase exhibited a loss of these structures.

CONCLUSION

Collagen removal from vocal fold tissue increases image brightness of underlying structures. This inverse relationship may be useful in treating vocal fold scarring in patients.