Multimodal imaging guidance for laser ablation in tracheal stenosis

Abstract

Objective/Hypothesis Laser-induced damage of tracheal wall microstructures might contribute to recurrence after bronchoscopic treatment of tracheal strictures. The purpose of this study was to demonstrate how multimodal imaging using white light bronchoscopy (WLB), endobronchial ultrasound (EBUS), and optical coherence tomography (OCT) might identify in vivo airway wall changes before and resulting from Nd:YAG laser ablation and dilation of tracheal stenosis. Study Design Case study. Methods Commercially available WLB, high frequency EBUS using a 20-MHz radial probe and time-domain, frontal imaging OCT systems were used to characterize the extent, morphology, and airway wall microstructures at the area of hypertrophic fibrotic tissue formation before, during and after treatment of postintubation tracheal stenosis. Results WLB revealed the location of a complex, extensive, severe stricture. EBUS showed a homogeneous layer overlying a hyperechogenic layer corresponding to disrupted cartilage. OCT showed a homogeneous light backscattering layer and absence of layered microstructures, confirming absence in close proximity of normal airway wall. After laser ablation, OCT of charred tissue showed high backscattering and shadowing artifacts. OCT of noncharred tissue showed a thinner, homogeneous, light backscattering layer. EBUS showed thinner but persistent hypertrophic tissue suggesting incomplete treatment. WLB revealed improved airway patency postprocedure and recurrence 3 weeks later. Conclusions EBUS identified cartilage disruption and residual hypertrophic tissue, the evidence of which might contribute to recurrence. OCT revealed homogeneous light backscaterring representing persistent noncharred hypertrophic tissues but it did not visualize cartilage disruption. Future studies are warranted to confirm whether these technologies can help guide bronchoscopic treatments.

Tomografia de coerência óptica broncoscópica

“…The movements should be smooth and coordinated in order not to compromise the quality of the image. The similarity between OCT images and those produced evaluation of smoke-induced airway injury, (2) evaluation of anastomosis and small airways in lung transplantation, performance of endobronchial biopsies, (21) and measurement of tracheobronchial stenosis, (20) as well as evaluation of normal microanatomy and small airway and smooth muscle thickening in asthma patients, (22) COPD patients, (23) cystic fibrosis patients, and smokers, (24,25) together with pre-and post-bronchial thermoplasty evaluation. (26) In addition, OCT can aid in determining the size of the bronchi in the endoscopic treatment of emphysema with one-way valves.…”

“…(19) Because it enables high-resolution real-time imaging without exposure to radiation and because it is compatible with bronchoscopy, OCT has the potential to become a powerful tool in future lung research. (20) Minimally invasive visualization of tissue anatomy provides important information for the diagnosis and clinical management of a wide range of diseases.…”

“…Those authors suggested that OCT in conjunction with bronchoscopy can (20) used endobronchial ultrasound and OCT in order to evaluate postintubation benign tracheal stenosis, in an attempt to find changes that could guide them in identifying the best treatment. The resolution of OCT was found to be 25 µm, compared with 100 µm of endobronchial ultrasound with a 20-MHz radial probe, which required a liquid interface (water-filled balloon) for image acquisition.…”

Recent advances in optical coherence tomography for the diagnoses of lung disorders

“…Both endobronchial ultrasound and OCT were able to provide real time images differentiating normal tissue from hypertrophic and fibrotic tissue as well as cartilage. In this case, OCT was able to provide margins for the area of stenosis, and possibly prevent both excessive unresected hypertrophic and fibrotic tissue as well as excessive destruction of normal tissue [41]. …”

“…Furthermore, the use of targeted laser energy to induce localized zones of thermal coagulation and necrosis has been investigated ex vivo and in vivo in animal studies. The effects of laser assisted mechanical dilation in tracheal stenosis were recently investigated and it was noticed that there were clear differences in the OCT imaging at the level of stenosis, in comparison with the normal airway wall structures, and that the charred tissue absorbs the light, the penetration is reduced and the OCT imaging is compromised (Figure 3) [41]. If these findings are validated in larger studies, then real time OCT imaging feedback during laser application could soon become applicable in clinical practice.…”