In vivo probe‐based confocal laser endomicroscopy in chronic interstitial lung diseases: Specific descriptors and correlation with chest CT

Vaporization of perfluorocarbon attenuates sea-water-drowning-induced acute lung injury by deactivating the NLRP3 inflammasomes in canines

Seawater-drowning-induced acute lung injury (SD-ALI) is a life-threatening disorder characterized by increased alveolar-capillary permeability, an excessive inflammatory response, and refractory hypoxemia. Perfluorocarbons (PFCs) are biocompatible compounds that are chemically and biologically inert and lack toxicity as oxygen carriers, which could reduce lung injury in vitro and in vivo. The aim of our study was to explore whether the vaporization of PFCs could reduce the severity of SD-ALI in canines and investigate the underlying mechanisms. Eighteen beagle dogs were randomly divided into three groups: the seawater drowning (SW), perfluorocarbon (PFC), and control groups. The dogs in the SW group were intratracheally administered seawater to establish the animal model. The dogs in the PFC group were treated with vaporized PFCs. Probe-based confocal laser endomicroscopy (pCLE) was performed at 3 h. The blood gas, volume air index (VAI), pathological changes, and wet-to-dry (W/D) lung tissue ratios were assessed. The expression of heme oxygenase-1 (HO-1), nuclear respiratory factor-1 (NRF1), and NOD-like receptor family pyrin domain containing-3 (NLRP3) inflammasomes was determined by means of quantitative real-time polymerase chain reaction (qRT-PCR) and immunological histological chemistry. The SW group showed higher lung injury scores and W/D ratios, and lower VAI compared to the control group, and treatment with PFCs could reverse the change of lung injury score, W/D ratio and VAI. PFCs deactivated NLRP3 inflammasomes and reduced the release of caspase-1, interleukin-1β (IL-1β), and interleukin-18 (IL-18) by enhancing the expression of HO-1 and NRF1. Our results suggest that the vaporization of PFCs could attenuate SD-ALI by deactivating NLRP3 inflammasomes via the HO-1/NRF1 pathway.

[Probe based confocal laser endomicroscopy in thoracic endoscopy]

INTRODUCTION

Probe based confocal laser endomicroscopy (pCLE) is a new endoscopic imaging technology. It uses mini probes which can be introduced through the working channels of endoscopes. Whenever applied on the tissue of interest, they allow imaging of tissue at a cellular level.

STATE OF ART

In the filed of pleuropulmonary malignancies, pCLE showed mostly its ability to guide biopsies samplings. Those results need to be validated in larger prospective studies. In interstitial lung diseases, pCLE provides information complementary to other clinical and paraclinical data. The valuability of these informations need to be investigated further, prospectively in randomized trials. In obstructive pulmonary diseases, pCLE is able to investigate the structural and functional relationships between pulmonary structures. pCLE showed good ability in the identification of acute cellular rejection after lung transplantation.

PERSPECTIVES AND CONCLUSION

For the time being, pCLE is not part of routine clinical practice. The data available need to be validated in larger randomized prospective trials, before it can be recommended as a guiding tool for biopsies or as a diagnostic tool for pathologic process. New fluorophores are now available. They are specific of some molecular sequences, allowing the enhancement of specific targets within the sample studied.

The cryobiopsy in interstitial lung diseases guided by probe-based confocal laser endomicroscopy is feasible

BACKGROUND

Transbronchial lung cryobiopsy (TBLB) is routinely used to diagnose the interstitial lung disease (ILD). These results are consistent with those of surgical lung biopsy. Fluoroscopy is also used to confirm the final position of the cryoprobe; however, it can increase radiation exposure for both patients and medical care personnel. Probe-based confocal laser endomicroscopy (pCLE) is a novel optical imaging technique that allows real-time imaging at the cellular level in vivo. pCLE technology can also be used to identify malignancy, acute rejection in lung transplantation, amiodarone lung, and pulmonary alveolar proteinosis and visualize elastin fibres in the alveolar compartment.

OBJECTIVES

The aim of this study is to investigate the ability of pCLE to distinguish fibrotic pulmonary issues from normal lung disease and the safety and feasibility of CLE-guided bronchoscopy and transbronchial lung cryobiopsy (TBLC) in patients with interstitial lung disease (ILD).

METHODS

pCLE images from 17 ILD patients were obtained during TBLB. These images were then compared with histology results to assess the correspondence rate.

RESULTS

pCLE imaging of the alveolar structures was performed. Key characteristics were visible, which could potentially influence the diagnostic rate (fibrotic areas) and the complication rate (blood vessel and pleura).

CONCLUSION

pCLE may reduce complications and increase the diagnostic yield. It is a potential guidance tool for cryobiopsy in the patients with ILD without fluoroscopy.

Clinical Application of Confocal Laser Endomircoscopy Combined with Cryobiopsy in the Diagnosis of Interstitial Lung Disease

INTRODUCTION

Confocal laser endomicroscopy (CLE) has the characteristics of high resolution, real-time imaging, and no radiation, which is helpful for the precise and effective implementation of transbronchial cryobiopsy (TBCB). The study aimed to compare the efficacy and safety of TBCB combined with CLE (CLE group) or fluoroscopy (fluoroscopy group) in the diagnosis of interstitial lung disease (ILD).

METHODS

From a prospective randomized controlled trial, 80 patients with undiagnosed ILD or ILD requiring biopsy between January 2022 and November 2022 were randomly assigned to CLE group and fluoroscopy group. The rate to reach an etiological diagnosis of ILD, maximum cross-sectional area of specimens, operation time, and complications were compared between the two groups.

RESULTS

The rate to reach an etiological diagnosis in the CLE group was significantly higher than that in the fluoroscopy group (95.0% vs. 80.0%, p < 0.05), but there was no difference in the maximum cross-sectional area of the specimens (42.1 ± 10.1 mm2 vs. 41.5 ± 10.3 mm2, p > 0.05). In terms of operation time, the CLE group was significantly shorter than the fluoroscopy group (37.6 ± 10.6 min vs. 54.8 ± 24.9 min, p < 0.05). The bleeding volume in the CLE group was significantly lower than that in the fluoroscopy group (4.9 ± 3.6 mL/case vs. 9.0 ± 9.2 mL/case, p < 0.05). Further analysis showed that the incidence of moderate bleeding was also lower in the CLE group (20.0% vs. 75.0%, p < 0.001). In addition, the incidence of pneumothorax in the CLE group was significantly lower than that in the fluoroscopy group (0 vs. 25.0%, p < 0.001).

CONCLUSIONS

Compared with simple fluoroscopy, the combination of CLE significantly improves the rate of etiological diagnosis, shortens the operation time, and reduces complications such as bleeding and pneumothorax.

The role of confocal laser endomicroscopy in pulmonary medicine

Accurate diagnosis and subsequent therapeutic options in pulmonary diseases mainly rely on imaging methods and histological assessment. However, imaging examinations are hampered by the limited spatial resolution of images and most procedures that are related to histological assessment are invasive with associated complications. As a result, a high-resolution imaging technology - confocal laser endomicroscopy (CLE), which is at the forefront and enables real-time microscopic visualisation of the morphologies and architectures of tissues or cells - has been developed to resolve the clinical dilemma pertaining to current techniques. The current evidence has shown that CLE has the potential to facilitate advanced diagnostic capabilities, to monitor and to aid the tailored treatment regime for patients with pulmonary diseases, as well as to expand the horizon for unravelling the mechanism and therapeutic targets of pulmonary diseases. In the future, if CLE can be combined with artificial intelligence, early, rapid and accurate diagnosis will be achieved through identifying the images automatically. As promising as this technique may be, further investigations are required before it can enter routine clinical practice.

Advances in bronchoscopic optical coherence tomography and confocal laser endomicroscopy in pulmonary diseases

PURPOSE OF REVIEW

Imaging techniques play a crucial role in the diagnostic work-up of pulmonary diseases but generally lack detailed information on a microscopic level. Optical coherence tomography (OCT) and confocal laser endomicroscopy (CLE) are imaging techniques which provide microscopic images in vivo during bronchoscopy. The purpose of this review is to describe recent advancements in the use of bronchoscopic OCT- and CLE-imaging in pulmonary medicine.

RECENT FINDINGS

In recent years, OCT- and CLE-imaging have been evaluated in a wide variety of pulmonary diseases and demonstrated to be complementary to bronchoscopy for real-time, near-histological imaging. Several pulmonary compartments were visualized and characteristic patterns for disease were identified. In thoracic malignancy, OCT- and CLE-imaging can provide characterization of malignant tissue with the ability to identify the optimal sampling area. In interstitial lung disease (ILD), fibrotic patterns were detected by both (PS-) OCT and CLE, complementary to current HRCT-imaging. For obstructive lung diseases, (PS-) OCT enables to detect airway wall structures and remodelling, including changes in the airway smooth muscle and extracellular matrix.

SUMMARY

Bronchoscopic OCT- and CLE-imaging allow high resolution imaging of airways, lung parenchyma, pleura, lung tumours and mediastinal lymph nodes. Although investigational at the moment, promising clinical applications are on the horizon.

Confocal laser endomicroscopy to guide sampling of a pure ground-glass opacity

We read with great interest the article “Needle-based confocal laser endomicroscopy [CLE] for real-time diagnosing and staging of lung cancer” by Wijmanset al. [1], recently published in the European Respiratory Journal, demonstrating the feasibility and safety of realtime lung cancer detection by endosonography-guided CLE. The authors elegantly describe three CLE characteristics for lung cancer: dark, enlarged pleomorphic cells; dark clumps; and directional streaming. The accuracy of CLE for detecting malignancy was 90% in tumours and 89% in metastatic lymph nodes.

Confocal laser endomicroscopy imaging of lepidic adenocarcinomas is feasible. This technique should be further evaluated as a realtime guiding tool during virtual electromagnetic navigation bronchoscopy for ground-glass opacitieshttps://bit.ly/3uzTcMU

Solitary pulmonary nodule imaging approaches and the role of optical fibre-based technologies

Solitary pulmonary nodules (SPNs) are a clinical challenge, given there is no single clinical sign or radiological feature that definitively identifies a benign from a malignant SPN. The early detection of lung cancer has a huge impact on survival outcome. Consequently, there is great interest in the prompt diagnosis, and treatment of malignant SPNs. Current diagnostic pathways involve endobronchial/transthoracic tissue biopsies or radiological surveillance, which can be associated with suboptimal diagnostic yield, healthcare costs and patient anxiety. Cutting-edge technologies are needed to disrupt and improve, existing care pathways. Optical fibre-based techniques, which can be delivered via the working channel of a bronchoscope or via transthoracic needle, may deliver advanced diagnostic capabilities in patients with SPNs. Optical endomicroscopy, an autofluorescence-based imaging technique, demonstrates abnormal alveolar structure in SPNs in vivo Alternative optical fingerprinting approaches, such as time-resolved fluorescence spectroscopy and fluorescence-lifetime imaging microscopy, have shown promise in discriminating lung cancer from surrounding healthy tissue. Whilst fibre-based Raman spectroscopy has enabled real-time characterisation of SPNs in vivo Fibre-based technologies have the potential to enable in situ characterisation and real-time microscopic imaging of SPNs, which could aid immediate treatment decisions in patients with SPNs. This review discusses advances in current imaging modalities for evaluating SPNs, including computed tomography (CT) and positron emission tomography-CT. It explores the emergence of optical fibre-based technologies, and discusses their potential role in patients with SPNs and suspected lung cancer.

Core crosstalk in ordered imaging fiber bundles

Coherent fiber bundles are used widely for imaging. Commonly, disordered arrays of randomly sized fiber cores avoid proximity between like-cores, which would otherwise result in increased core crosstalk and a negative impact on imaging. Recently, stack-and-draw fiber manufacture techniques have been used to produce fibers with a controlled core layout to minimize core crosstalk. However, one must take manufacturing considerations into account during stack-and-draw fiber design in order to avoid impractical or unachievable fabrication. This comes with a set of practical compromises, such as using only a small number of different core sizes. Through characterization of core crosstalk patterns, this Letter aims to aid the understanding of crosstalk limitations imposed by such compromises in the core layout made for ease of fabrication.

Diagnostic approach of fibrosing interstitial lung diseases of unknown origin

Interstitial lung diseases encompass a broad range of numerous individual conditions, some of them characterized histologically by fibrosis, especially idiopathic pulmonary fibrosis, nonspecific interstitial pneumonia, chronic hypersensitivity pneumonia, interstitial lung disease associated with connective tissue diseases, and unclassifiable interstitial lung disease. The diagnostic approach relies mainly on the clinical evaluation, especially assessment of the patient's demographics, history, smoking habits, occupational or domestic exposures, use of drugs, and on interpretation of high-quality HRCT of the chest. Imaging is key to the initial diagnostic approach, and often can confirm a definite diagnosis, particularly a diagnosis of idiopathic pulmonary fibrosis when showing a pattern of usual interstitial pneumonia in the appropriate context. In other cases, chest HRCT may orientate toward an alternative diagnosis and appropriate investigations to confirm the suspected diagnosis. Autoimmune serology helps diagnosing connective disease. Indications for bronchoalveolar lavage and for lung biopsy progressively become more restrictive, with better considerations for their discriminate value, of the potential risk associated with the procedure, and of the anticipated impact on management. Innovative techniques and genetics are beginning to contribute to diagnosing interstitial lung disease and to be implemented routinely in the clinic. Multidisciplinary discussion, enabling interaction between pulmonologists, chest radiologists, pathologists and often other healthcare providers, allows integration of all information available. It increases the accuracy of diagnosis and prognosis prediction, proposes a first-choice diagnosis, may suggest additional investigations, and often informs the management. The concept of working diagnosis, which can be revised upon additional information being made available especially longitudinal disease behaviour, helps dealing with diagnostic uncertainty inherent to interstitial lung diseases and facilitates management decisions. Above all, the clinical approach and how thoroughly the patient's history and possible exposures are assessed determine the possibility of an accurate diagnosis.

Automated evaluation of probe-based confocal laser endomicroscopy in the lung

RATIONALE

Probe-based confocal endomicroscopy provides real time videos of autoflourescent elastin structures within the alveoli. With it, multiple changes in the elastin structure due to different diffuse parenchymal lung diseases have previously been described. However, these evaluations have mainly relied on qualitative evaluation by the examiner and manually selected parts post-examination.

OBJECTIVES

To develop a fully automatic method for quantifying structural properties of the imaged alveoli elastin and to perform a preliminary assessment of their diagnostic potential.

METHODS

46 patients underwent probe-based confocal endomicroscopy, of which 38 were divided into 4 groups categorizing different diffuse parenchymal lung diseases. 8 patients were imaged in representative healthy lung areas and used as control group. Alveolar elastin structures were automatically segmented with a trained machine learning algorithm and subsequently evaluated with two methods developed for quantifying the local thickness and structural connectivity.

MEASUREMENTS AND MAIN RESULTS

The automatic segmentation algorithm performed generally well and all 4 patient groups showed statistically significant differences with median elastin thickness, standard deviation of thickness and connectivity compared to the control group.

CONCLUSION

Alveoli elastin structures can be quantified based on their structural connectivity and thickness statistics with a fully-automated algorithm and initial results highlight its potential for distinguishing parenchymal lung diseases from normal alveoli.

Advances in Optical Coherence Tomography and Confocal Laser Endomicroscopy in Pulmonary Diseases

Diagnosing and monitoring pulmonary diseases is highly dependent on imaging, physiological function tests and tissue sampling. Optical coherence tomography (OCT) and confocal laser endomicroscopy (CLE) are novel imaging techniques with near-microscopic resolution that can be easily and safely combined with conventional bronchoscopy. Disease-related pulmonary anatomical compartments can be visualized, real time, using these techniques. In obstructive lung diseases, airway wall layers and related structural remodelling can be identified and quantified. In malignant lung disease, normal and malignant areas of the central airways, lung parenchyma, lymph nodes and pleura can be discriminated. A growing number of interstitial lung diseases (ILDs) have been visualized using OCT or CLE. Several ILD-associated structural changes can be imaged: fibrosis, cellular infiltration, bronchi(ol)ectasis, cysts and microscopic honeycombing. Although not yet implemented in clinical practice, OCT and CLE have the potential to improve detection and monitoring pulmonary diseases and can contribute in unravelling the pathophysiology of disease and mechanism of action of novel treatments. Indeed, assessment of the airway wall layers with OCT might be helpful when evaluating treatments targeting airway remodelling. By visualizing individual malignant cells, CLE has the potential as a real-time lung cancer detection tool. In the future, both techniques could be combined with laser-enhanced fluorescent-labelled tracer detection. This review discusses the value of OCT and CLE in pulmonary medicine by summarizing the current evidence and elaborating on future perspectives.

In Vivo Endomicroscopy of Lung Injury and Repair in ARDS: Potential Added Value to Current Imaging

BACKGROUND

Standard clinical imaging of the acute respiratory distress syndrome (ARDS) lung lacks resolution and offers limited possibilities in the exploration of the structure-function relationship, and therefore cannot provide an early and clear discrimination of patients with unexpected diagnosis and unrepair profile. The current gold standard is open lung biopsy (OLB). However, despite being able to reveal precise information about the tissue collected, OLB cannot provide real-time information on treatment response and is accompanied with a complication risk rate up to 25%, making longitudinal monitoring a dangerous endeavor. Intravital probe-based confocal laser endomicroscopy (pCLE) is a developing and innovative high-resolution imaging technology. pCLE offers the possibility to leverage multiple and specific imaging probes to enable multiplex screening of several proteases and pathogenic microorganisms, simultaneously and longitudinally, in the lung. This bedside method will ultimately enable physicians to rapidly, noninvasively, and accurately diagnose degrading lung and/or fibrosis without the need of OLBs.

OBJECTIVES AND METHODS

To extend the information provided by standard imaging of the ARDS lung with a bedside, high-resolution, miniaturized pCLE through the detailed molecular imaging of a carefully selected region-of-interest (ROI). To validate and quantify real-time imaging to validate pCLE against OLB.

RESULTS

Developments in lung pCLE using fluorescent affinity- or activity-based probes at both preclinical and clinical (first-in-man) stages are ongoing-the results are promising, revealing correlations with OLBs in problematic ARDS.

CONCLUSION

It can be envisaged that safe, high-resolution, noninvasive pCLE with activatable fluorescence probes will provide a "virtual optical biopsy" and will provide decisive information in selected ARDS patients at the bedside.