Investigating in vivo airway wall mechanics during tidal breathing with optical coherence tomography

Abstract

Abstract. Optical coherence tomography (OCT) is a nondestructive imaging technique offering high temporal and spatial resolution, which makes it a natural choice for assessing tissue mechanical properties. We have developed methods to mechanically analyze the compliance of the rabbit trachea in vivo using tissue deformations induced by tidal breathing, offering a unique tool to assess the behavior of the airways during their normal function. Fourhundred images were acquired during tidal breathing with a custom-built endoscopic OCT system. The surface of the tissue was extracted from a set of these images via image processing algorithms, filtered with a bandpass filter set at respiration frequency to remove cardiac and probe motion, and compared to ventilatory pressure to calculate wall compliance. These algorithms were tested on elastic phantoms to establish reliability and reproducibility. The mean tracheal wall compliance (in five animals) was 1.3 ± 0.3×10 − 5 (mm Pa) − 1 . Unlike previous work evaluating airway mechanics, this new method is applicable in vivo, noncontact, and loads the trachea in a physiological manner. The technique may have applications in assessing airway mechanics in diseases such as asthma that are characterized by significant airway remodeling. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

Optical coherence elastography for tissue characterization: a review

“…An OCE study has taken the high-resolution endoscopic OCT images of the tracheal wall from live rabbit and produces the mapping of the compliance through the tracking of the displacement from the wall surface [158]. Such compliance map of the trachea has been shown to be able to indicate the location of the trachealis from in vivo experiments [158].…”

“…An OCE study has taken the high-resolution endoscopic OCT images of the tracheal wall from live rabbit and produces the mapping of the compliance through the tracking of the displacement from the wall surface [158]. Such compliance map of the trachea has been shown to be able to indicate the location of the trachealis from in vivo experiments [158]. This type of OCE method that relies on the intrinsic stimulation of the tissue (such as the tidal breathing here and the diastolic pressure variation in intravascular OCE) has great potential to provide valuable mechanical information to directly complement the OCT structural imaging.…”

Novel imaging approaches in adult asthma and their clinical potential

“…It also has the potential to assess airway wall structure exactly at the time biopsy/histological samples are taken. A new OCT-based method has been recently proposed that analyzes airway compliance by comparing deflection of the surface of the tissue to ventilation pressure during tidal breathing [183].…”

Multi-modal anatomical optical coherence tomography and CT for in vivo dynamic upper airway imaging

“…Significant differences in fluctuations in airway area 8 or the patterns of dynamic airway motion 9 between healthy controls and patients with OSAS have been observed. In addition, assessing airway tissue mechanics in vivo could also be important for studying airway remodeling in diseases such as asthma 10, 11 . Fourier Domain OCT, owing to its high temporal and spatial resolution, is ideally suited for dynamic airway imaging.…”

“…Fourier Domain OCT, owing to its high temporal and spatial resolution, is ideally suited for dynamic airway imaging. A few studies 10, 11 have performed endoscopic OCT imaging under dynamic conditions, either during tidal breathing or under positive pressure ventilation. In such cases, a simple elastic phantom was typically used for the validation of dynamic OCT imaging or elastography.…”