At the recent AQL conference in Hong Kong, Daryush presented work from a collaboration between researchers at the MGH Voice Center and optics experts at Physical Sciences, Inc.
4D laryngeal imaging by synchronously combining OCT with videostroboscopy
Although laryngeal videostroboscopy continues to play a central role in diagnostic, surgical, and therapeutic decisions during the management of voice disorders, videostroboscopy is limited to 2D imaging of the vocal fold surface during phonation. The aim of the current work is to enhance videostroboscopy by synchronizing optical coherence tomography (OCT) through a common path probe to obtain 4D imaging of the mucosal wave and subsurface tissue morphology.
The developed OCT-strobe rigid endoscope integrated four subsystems: Imaging Probe, OCT Unit, Data Acquisition and Processing Unit, and Display.
The Imaging Probe combined swept-source OCT and video imaging channels through the same distal end optics and included a fiber collimator, folding mirror, beam divergence adjusting lens, and galvanometer-based scanning engine. A custom-built timing circuit synchronized OCT image data with videostroboscopic frames triggered by the fundamental frequency derived from an acoustic microphone. The Processing Unit enabled three modes of real-time vocal fold visualization: high-resolution morphological scan (M-scan), triggered kymographic scan (K-scan), and triggered 3D raster scan (C-scan).
Initial results were obtained from ex vivo larynx experiments in all three system modes to demonstrate real-time, calibrated three-dimensional imaging of the mucosal wave and subsurface tissue during self-sustained vocal fold tissue vibration. Subsurface morphology during phonation was highlighted in an experiment imaging hyaluronic acid injected underneath the vocal fold epithelial layer.
OCT technology was synchronized with videostroboscopy to dynamically capture 3D volumetric images of the vocal folds during phonation. Results warrant in vivo evaluation to ultimately aid in the management of vocal fold tissue lesions.