Automated working distance adjustment enables optical coherence tomography of the human larynx in awake patients

Abstract

Abstract. Optical coherence tomography (OCT) provides structural information of laryngeal tissue which is comparable to histopathological analysis of biopsies taken under general anesthesia. In awake patients, movements impede clinically useful OCT acquisition. Therefore, an automatic compensation of movements was implemented into a swept source OCT-laryngoscope. Video and OCT beam path were combined in one tube of 10-mm diameter. Segmented OCT images served as distance sensor and a feedback control adjusted the working distance between 33 and 70 mm by synchronously translating the reference mirror and focusing lens. With this motion compensation, the tissue was properly visible in up to 88% of the acquisition time. During quiet respiration, OCT contrasted epithelium and lamina propria. Mean epithelial thickness was measured to be 109 and 135 μm in female and male, respectively. Furthermore, OCT of mucosal wave movements during phonation enabled estimation of the oscillation frequency and amplitude. Regarding clinical issues, the OCT-laryngoscope with automated working distance adjustment may support the estimation of the depth extent of epithelial lesions and contribute to establish an indication for a biopsy. Moreover, OCT of the vibrating vocal folds provides functional information, possibly giving further insight into mucosal behavior during the vibratory cycle.

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

“…Previously, OCT has been used to qualitatively describe normal vocal fold structure while additional studies have described the appearance of benign and malignant vocal fold lesions . Recent studies have adapted OCT systems to image laryngeal tissue in awake patients and monitor the development of subglottic stenosis in intubated newborns …”

“…[4][5][6][7][8][9][10] Recent studies have adapted OCT systems to image laryngeal tissue in awake patients and monitor the development of subglottic stenosis in intubated newborns. [11][12][13] A long-term goal of our group has been to use OCT to characterize vocal fold development. For decades, histological analysis and electron microscopy were the mainstays of studying vocal fold structure.…”

Effect of saline inhalation on vocal fold epithelial morphology evaluated by optical coherence tomography

“…In this study, a specially designed OCT system was used, based on the light source and detection unit of a commercial OCT (OCS1300SS, Thorlabs, Newton, NJ), adapted to a rigid endoscope . The light source is a swept source laser emitting at a central wavelength of 1,325 nanometers (nm) and having a bandwidth of 100 nm.…”

“…To compensate for movements of the patient and the handheld OCT device, the working distance was adjusted automatically and continuously throughout the laryngoscopic procedure. The axial position of the tissue surface was detected in the OCT images to register the current tissue position, and imaging depth and focus of the endoscope were moved to compensate for position errors . The timing of the motion compensation was adjusted with the imaging rate of the OCT to apply in every second B‐scan.…”

“…In order to overcome these practical limitations, we developed a rigid OCT laryngoscope that guides OCT and video imaging in a common optical path. The automatic range and autofocus system implemented in the OCT laryngoscope provides an active motion compensation during the examination . This newly developed device provides all the necessary features to perform a rigid laryngoscopy in a controlled way and at the same time to generate OCT images of the tissue surface of the larynx.…”