Probe-based confocal laser endomicroscopy of the respiratory tract: A data consistency analysis

Optical Biopsies Using Probe-Based Confocal Laser Endomicroscopy for Autoimmune Pulmonary Alveolar Proteinosis

INTRODUCTION

Increasing numbers of cases of mild asymptomatic pulmonary alveolar proteinosis (PAP) are being reported with the recent increase in chest computed tomography (CT). Bronchoscopic diagnosis of mild PAP is challenging because of the patchy distribution of lesions, which makes it difficult to obtain sufficient biopsy samples. Additionally, the pathological findings of mild PAP, particularly those that differ from severe PAP, have not been fully elucidated. This study aimed to clarify the pathological findings of mild PAP and the usefulness of optical biopsy using probe-based confocal laser endomicroscopy (pCLE).

METHODS

We performed bronchoscopic optical biopsy using pCLE and tissue biopsy in 5 consecutive patients with PAP (three with mild PAP and two with severe PAP). We compared the pCLE images of mild PAP with those of severe PAP by integrating clinical findings, tissue pathology, and chest CT images.

RESULTS

pCLE images of PAP showed giant cells with strong fluorescence, amorphous substances, and thin alveolar walls. Images of affected lesions in mild PAP were equivalent to those obtained in arbitrary lung lesions in severe cases. All 3 patients with mild PAP spontaneously improved or remained stable after ≥3 years of follow-up. Serum autoantibodies to granulocyte-macrophage colony-stimulating factor were detected in all 5 cases.

CONCLUSION

Optical biopsy using pCLE can yield specific diagnostic findings, even in patients with mild PAP. pCLE images of affected areas in mild and severe PAP showed similar findings, indicating that the dysfunction level of pathogenic alveolar macrophages in affected areas is similar between both disease intensities.

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.

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.

Comparison of in vivo probe-based confocal laser endomicroscopy with histopathology in lung cancer: A move toward optical biopsy

BACKGROUND AND OBJECTIVE

The development of novel technologies has increased the yield from transbronchial biopsies while preserving patient safety by guiding biopsies to the area of interest. Other technologies have helped identify pre-cancerous or sessile lesions in the endobronchial space by utilizing interactions between tissue and light at varying wavelengths. Probe-based confocal laser endomicroscopy (pCLE) is a new technology that encompasses the benefits of both guided biopsies and novel optical imaging in one device. This project compares pCLE images to the findings of light microscopy in non-small cell lung cancer (NSCLC).

METHODS

Patients who underwent bronchoscopies between July 2012 and January 2013 for evaluation of pulmonary lesions (transbronchial and endobronchial) were recruited. Histopathological images from malignant lesions were compared with the pCLE images obtained from the same area. The microscopic and pCLE images were reviewed side by side with the microscopic findings.

RESULTS

Images from pCLE correlate with some histopathological findings. pCLE changes seen in NSCLC consist of mottled elastin, septal studding and disorganization/fragmentation with increased friability. These changes also seem to correlate with degrees of differentiation.

CONCLUSIONS

pCLE can identify changes to the elastin composition of the airways and alveoli in lung cancer. These changes correlate with histopathology and may help indicate the presence of malignant changes in vivo.

Robotic-assisted microsurgery for an elective microsurgical practice

Robotic-assisted microsurgery can be utilized for either intracorporal or extracorporeal surgical procedures. Three-dimensional high-definition magnification, a stable ergonomic platform, elimination of physiologic tremor, and motion scaling make the robotic platform attractive for microsurgeons for complex procedures. Additionally, robotic assistance enables the microsurgeon to take microsurgery to challenging intracorporeal locations in a minimally invasive manner. Recent adjunctive technological developments offer the robotic platform enhanced optical magnification, improved intraoperative imaging, and more precise ablation techniques for microsurgical procedures. The authors present the current state-of-the art tools available in the robotic-assisted microsurgical platform.

Acute lung allograft rejection: diagnostic role of probe-based confocal laser endomicroscopy of the respiratory tract

BACKGROUND

Acute cellular rejection (AR) after lung transplantation may result in significant morbidity and mortality both on the short and long term. Transbronchial biopsy through flexible bronchoscopy is highly sensitive for the diagnosis of AR, but reproducibility of histopathologic interpretation is less convincing. Probe-based confocal laser endomicroscopy (pCLE), a novel imaging tool in the field of respiratory medicine, enables real-time imaging of the pulmonary acini.

METHODS

We performed 105 bronchoscopies in lung transplant recipients, combining both transbronchial biopsies and pCLE. We conducted an observational survey for pCLE findings in AR.

RESULTS

Calculations for cellularity showed a median cell count (ACA) of 50 (IQR 18 to 120) cells per microscopic field for AR and 10 (IQR 0 to 15) cells per microscopic field for matched controls (p = 0.0004). Cellular autofluorescence in the AR group was 1,163 (± 157) units and 489 (± 101) units for the matched controls (p = 0.0009). Autofluorescent cells were present in 73% (± 10) of the recorded frames in the AR group and in only 42% (± 9) of the recorded frames in the control group (p = 0.03). Contingency analysis for the presence/absence of ACA in the AR group versus the control group showed a sensitivity of 0.93 and a specificity of 0.46 (relative risk = 6.5 [95% CI 0.94 to 44.8], p = 0.01). The consecutive application of 3 pCLE criteria resulted in a sensitivity of 0.93 and a specificity of 0.83 for detection of AR.

CONCLUSION

Our observational survey suggests the existence of specific pCLE characteristics in patients with AR. Further efforts are necessary to validate these findings prospectively.

Advances in interventional pulmonology

Interventional pulmonology (IP) remains a rapidly expanding and evolving subspecialty focused on the diagnosis and treatment of complex diseases of the thorax. As the field continues to push the leading edge of medical technology, new procedures allow for novel minimally invasive approaches to old diseases including asthma, chronic obstructive pulmonary disease and metastatic or primary lung malignancy. In addition to technologic advances, IP has matured into a defined subspecialty, requiring formal training necessary to perform the advanced procedures. This need for advanced training has led to the need for standardization of training and the institution of a subspecialty board examination. In this review, we will discuss the dynamic field of IP as well as novel technologies being investigated or employed in the treatment of thoracic disease.