Subepithelial vascular patterns in bronchial dysplasias using a high magnification bronchovideoscope

Role of bronchoscopy in management of central squamous cell lung carcinoma in situ

Squamous cell carcinoma in situ (SCIS) is the pre-invasive stage of squamous cell carcinoma. Early detection and management of SCIS can prevent further progression. Although surgery and external beam radiation therapy are treatment options for SCIS, smaller lesions can be easily managed by bronchoscopic modalities like photodynamic therapy (PDT), cryotherapy, mechanical debulking with biopsy forceps, electrocautery and argon plasma coagulation (APC). Endobronchial brachytherapy (EBBT) and lasers may be judiciously utilized in selected cases. Although, previous studies of treatment modalities may have inadvertently included cases of invasive carcinomas, the advent of new technologies like radial probe endobronchial ultrasound (RP-EBUS) and optical coherence tomography (OCT) can help accurately determine the of depth of invasion. Superficial extent can also be better demarcated with techniques like auto-fluorescence bronchoscopy and narrow band imaging (NBI). New drugs for PDT with deeper penetration and less phototoxicity are being developed. These advances hopefully will allow us to perform superior clinical trials in future and improve our understanding of diagnosis and management of SCIS.

Image enhancement technology in bronchoscopy: a prospective multicentre study in lung cancer

Introduction

Patients with lung cancer may present with additional lesions in the central airways. Earlier studies have shown a relationship between vessel diameter, pattern and grade of malignancy. High-definition (HD+) bronchoscopy with image enhancement techniques (i-scan) detected more vascular abnormalities but correlation with pathology has not yet been established.

Methods

In this investigator-initiated, randomised, controlled, crossover, multicentre study in patients with suspected lung cancer, a HD+ bronchoscopy was performed with i-scan1 and i-scan2 settings in random order. Biopsies, visual grade and vascular pattern classification were obtained by endoscopists and blinded evaluation.

Results

In 107 patients, vascular patterns were classified in 48 tumours. Abrupt-ending vessels were predominantly found in squamous cell carcinoma but overall correlation between vessel pattern and histology was not significant (p=0.339). Additional lesions were detected in 35 patients (33%) with a correlation between vessel pattern and high-grade (pre-)invasive lesions (p<0.001). In 8.4% of the patients, relevant second lesions were detected which determined treatment and staging in 3% of all patients. Interobserver agreement was excellent for visual grading of the airway epithelium, but low for classifying vascular patterns. No significant detection rate difference was found by blinded and unblinded evaluation.

Conclusion

HD+ bronchoscopy with i-scan image enhancement readily detects additional lesions. In one-third of all the patients, additional lesions were detected. Their vascular pattern correlates to pathology outcome, but the interobserver correlation for vascular pattern classification is low. These lesions were relevant in 8.4% and affected treatment and work-up in 3% of the cases.

Trial registration number

NCT02285426; Results.

The technique of endoscopic airway tumor treatment

More than half of primary lung cancers are not resectable at diagnosis and 40% of deaths may be secondary to loco-regional disease. Many of these patients suffer from symptoms related to airways obstruction. Indications for therapeutic endoscopic treatment are palliation of dyspnea and other obstructive symptoms in advanced cancerous lesions and cure of early lung cancer. Bronchoscopic management is also indicated for all those patients suffering from benign or minimally invasive neoplasm who are not suitable for surgery due to their clinical conditions. Clinicians should select cases, evaluating tumor features (size, location) and patient characteristics (age, lung function impairment) to choose the most appropriate endoscopic technique. Laser therapy, electrocautery, cryotherapy and stenting are well-described techniques for the palliation of symptoms due to airway involvement and local treatment of endobronchial lesions. Newer technologies, with an established role in clinical practice, are endobronchial ultrasound (EBUS), autofluorescence bronchoscopy (AFB), and narrow band imaging (NBI). Other techniques, such as endobronchial intra-tumoral chemotherapy (EITC), EBUS-guided-transbronchial needle injection or bronchoscopy-guided radiofrequency ablation (RFA), are in development for the use within the airways. These endobronchial interventions are important adjuncts in the multimodality management of lung cancer and should become standard considerations in the management of patients with advanced lung cancer, benign or otherwise not approachable central airway lesions. We aimed at revising several endobronchial treatment modalities that can augment standard antitumor therapies for advanced lung cancer, including rigid and flexible bronchoscopy, laser therapy, endobronchial prosthesis, and photodynamic therapy (PDT).

The role of bronchoscopy in the diagnosis of early lung cancer: a review

Lung cancer is the leading cause of cancer-related deaths worldwide with an overall 5-year survival rate of 17% after diagnoses. Indeed many patients tend to have a very poor prognosis, due to being diagnosed at an advanced stage. Conversely patients who are diagnosed at an early stage have a 5-year survival >70%, indicating that early detection of lung cancer is crucial to improve survival. Although flexible bronchoscopy is a relatively non-invasive procedure for patients suspected of having lung cancer, only 29% of carcinoma in situ (CIS) and 69% of microinvasive tumors were detectable using white light bronchoscopy (WLB) alone. As a result, in the past two decades, new bronchoscopic techniques have been developed to increase the yield and diagnostic accuracy, such as autofluorescence bronchoscopy (AFB), narrow band imaging (NBI) and high magnification bronchovideoscopy (HMB). However, due to the low specificity and the limitation to detect only proximal bronchial tree, new probe-based technologies have been introduced: radial endobronchial ultrasound (R-EBUS), optical coherence tomography (OCT), confocal laser endomicroscopy (CLE) and laser Raman spectroscopy (LRS). To date, although tissue biopsy remains the gold standard for diagnosing malignant/premalignant airway disease and some techniques are still investigational, bronchoscopic technologies can be considered the safest and most accurate tools to evaluate both central and distal airway mucosa.

Techniques of endoscopic airway tumor treatment

Interventional bronchoscopy has a predominant role in the management of both early and advanced-stage airway tumors. Given the very poor prognosis of lung cancer, there is a need for new tools to improve early detection and bronchoscopic treatment of endo-bronchial precancerous lesions. In more advanced stages, interventional bronchoscopy plays an important role, as nearly a third of lung cancers lead to proximal airway obstruction. This will cause great discomfort or even life-threatening symptoms related to local extension, such as dyspnea, post-obstructive pneumonia, and hemoptysis. Surgery for very locally advanced disease is only effective for a limited number of patients and the effects of conventional antitumor therapies, like radiation therapy or chemotherapy, are inconstant and are too delayed in a palliative context. In this review, we aim to provide pulmonologists with an exhaustive technical overview of (I) the bronchoscopic management of benign endobronchial lesions; (II) the bronchoscopic management of malignant tumors, including the curative treatment of localized lesions and palliative management of malignant proximal airway stenosis; and (III) descriptions of the emerging endoscopic techniques used to treat peripheral lung tumors.

Image-enhanced bronchoscopic evaluation of bronchial mucosal microvasculature in COPD

Background

Bronchial vascular remodeling is an underresearched component of airway remodeling in COPD. Image-enhanced bronchoscopy may offer a less invasive method for studying bronchial microvasculature in COPD.

Objectives

To evaluate endobronchial mucosal vasculature and changes in COPD by image-enhanced i-scan3 bronchoscopy and correlate them pathologically by analyzing bronchial mucosal biopsies.

Methods

This case–control study analyzed 29 COPD patients (41.4% Global initiative for chronic Obstructive Lung Disease B [GOLD B] and 58.6% GOLD D) and ten healthy controls admitted at Alexandria Main University Hospital, Egypt. Combined high-definition white light bronchoscopy (HD WLB) with i-scan3 was used to evaluate endobronchial mucosal microvasculature. The vascularity was graded according to the level of mucosal red discoloration (ie, endobronchial erythema) from decreased discoloration to normal, mild, moderate, and severe increased red discoloration (G−1, G0, G+1, G+2, and G+3, respectively) and scored by three bronchoscopists independently. Bronchial mucosal biopsies were taken for microvascular density counting using anti-CD34 antibody as angiogenesis marker.

Results

Different grades of endobronchial erythema were observed across/within COPD patients using combined HD WLB + i-scan3, with significant agreement among scorers (P=0.031; median score of G+1 [G−1–G+2]) being higher in GOLD D (P=0.001). Endobronchial erythema significantly correlated with COPD duration, exacerbation frequency, and body mass index (P<0.05). Angiogenesis was significantly decreased among COPD patients versus controls (10.6 [8–13.3] vs 14 [11–17.1]; P=0.02). Mucosal surface changes (including edema, atrophy, and nodules) were better visualized by the combined HD WLB + i-scan3 rather than HD WLB alone.

Conclusion

Combined HD WLB + i-scan3 seems to be valuable in evaluating mucosal microvasculature and surface changes in COPD, which may represent vasodilatation rather than angiogenesis.

Narrow-band imaging bronchoscopy in the detection of premalignant airway lesions: a meta-analysis of diagnostic test accuracy

OBJECTIVES

Both autofluorescence imaging bronchoscopy and narrow-band imaging have shown promise in the detection of premalignant airway lesions, each by utilizing different bandwidths of lights for better characterization of the mucosal and submucosal vascular grid. Since previously published meta-analyses have shown poor specificity of autofluorescence imaging bronchoscopy, we specifically studied the diagnostic accuracy of narrow-band imaging alone and in combination with autofluorescence imaging bronchoscopy in the detection of premalignant airway lesions.

METHODS

After an extensive search of eligible studies from PubMed and Medline, extracted data were pooled with weighted averages. Symmetrical summary-receiver operating characteristic curves were constructed to summarize the results quantitatively. Study heterogeneity was assessed by the I(2) index.

RESULTS

Analysis of data from eight studies on narrow-band imaging showed a pooled sensitivity of 0.80 [95% confidence interval (CI): 0.77-0.83] and a pooled specificity of 0.84 (95% CI: 0.81-0.86). Summary-receiver operating characteristic curves from the data on narrow-band imaging calculated an area-under-the-curve of 0.908 (standard error 0.01). The diagnostic odds ratio of narrow-band imaging was 31.49 (95% CI: 12.17-81.45). Data from studies where narrow-band imaging and autofluorescence imaging bronchoscopy were used together showed a pooled sensitivity, specificity, area-under-the-curve and diagnostic odds ratios of 0.86 (95% CI: 0.82-0.89), 0.75 (95% CI: 0.71-0.79), 0.964 (standard error 0.05) and 27.96 (95% CI: 3.04-257.21), respectively.

CONCLUSIONS

Our findings indicate that in the evaluation of premalignant airway lesions, narrow-band imaging has a higher sensitivity, specificity and diagnostic odds ratios compared with autofluorescence imaging bronchoscopy. However, combining autofluorescence imaging bronchoscopy and narrow-band imaging does not significantly improve test performance characteristics.

High definition bronchoscopy: a randomized exploratory study of diagnostic value compared to standard white light bronchoscopy and autofluorescence bronchoscopy

Background

Videobronchoscopy is an essential diagnostic procedure for evaluation of the central airways and pivotal for the diagnosis and staging of lung cancer. Technological improvements have resulted in high definition (HD) images with advanced real time image enhancement techniques (i-scan).

Objectives

In this study we aimed to explore the sensitivity of HD+ i-scan bronchoscopy for detection of epithelial changes like vascular abnormalities and suspicious preinvasive lesions, and tumors.

Methods

In patients scheduled for a therapeutic or diagnostic procedure under general anesthesia videos of the bronchial tree were made using 5 videobronchoscopy modes in random order: normal white light videobronchoscopy (WLB), HD-bronchoscopy (HD), HD bronchoscopy with surface enhancement technique (i-scan1), HD with surface- and tone enhancement technique (i-scan2) and dual mode autofluorescence videobronchoscopy (AFB). The videos were scored in random order by two independent and blinded expert bronchoscopists.

Results

In 29 patients all videos were available for analysis. Vascular abnormalities were scored most frequently in HD + i-scan2 bronchoscopy (1.33 ± 0.29 abnormal or suspicious sites per patient) as compared to 0.12 ± 0.05 site for AFB (P = 0.003). Sites suspicious for preinvasive lesions were most frequently reported using AFB (0.74 ± 0.12 sites per patient) as compared to 0.17 ± 0.06 for both WLB and HD bronchoscopy (P = 0.003). Tumors were detected equally by all modalities. The preferred modality was HD bronchoscopy with i-scan (tone- plus surface and surface enhancement in respectively 38% and 35% of cases P = 0.006).

Conclusions

This study shows that high definition bronchoscopy with image enhancement technique may result in better detection of subtle vascular abnormalities in the airways. Since these abnormalities may be related to preneoplastic lesions and tumors this is of clinical relevance. Further investigations using this technique relating imaging to histology are warranted.

Advanced bronchoscopic techniques in diagnosis and staging of lung cancer

The role of advanced brochoscopic diagnostic techniques in detection and staging of lung cancer has steeply increased in recent years. Bronchoscopic imaging techniques became widely available and easy to use. Technical improvement led to merging in technologies making autofluorescence or narrow band imaging incorporated into one bronchoscope. New tools, such as autofluorescence imagining (AFI), narrow band imaging (NBI) or fuji intelligent chromo endoscopy (FICE), found their place in respiratory endoscopy suites. Development of endobronchial ultrasound (EBUS) improved minimally invasive mediastinal staging and diagnosis of peripheral lung lesions. Linear EBUS proven to be complementary to mediastinoscopy. This technique is now available in almost all high volume centers performing bronchoscopy. Radial EBUS with mini-probes and guiding sheaths provides accurate diagnosis of peripheral pulmonary lesions. Combining EBUS guided procedures with rapid on site cytology (ROSE) increases diagnostic yield even more. Electromagnetic navigation technology (EMN) is also widely used for diagnosis of peripheral lesions. Future development will certainly lead to new improvements in technology and creation of new sophisticated tools for research in respiratory endoscopy. Broncho-microscopy, alveoloscopy, optical coherence tomography are some of the new research techniques emerging for rapid technological development.

Diffuse reflectance spectroscopy in Barrett's esophagus: developing a large field-of-view screening method discriminating dysplasia from metaplasia

We evaluated diffuse reflectance spectroscopy implemented as a small field-of-view technique for discrimination of dysplasia from metaplasia in Barrett's esophagus as an adjuvant to autofluorescence endoscopy. Using linear discriminant analysis on 2579 spectra measured in 54 patients identified an optimum a 4-wavelength classifier (at 485, 513, 598 and 629 nm). Sensitivity and specificity for a test data set were 0.67 and 0.85, respectively. Spectroscopic results show that this technique could be implemented in wide-field imaging mode to improve the accuracy of existing endoscopy techniques for finding early pre-malignant lesions in Barrett's esophagus. Results show that the discrimination occurs likely due to redistribution of blood content in the tissue sensed by the optical probing with the wavelength-dependent sampling depth.

Detection and minimally invasive treatment of early squamous lung cancer

Non-small cell lung cancer (NSCLC) is the most common cause of cancer deaths worldwide. The majority of patents presenting with NSCLC have advanced disease, which precludes curative treatment. Early detection and treatment might result in the identification of more patients with early central lung cancer and improve survival. In addition, the study of early lung cancer improves understanding of lung carcinogenesis and might also reveal new treatment targets for advanced lung cancer. Bronchoscopic investigation of the central airways can reveal both early central lung cancer in situ (stage 0) and other preinvasive lesions such as dysplasia. In the current review we discuss the detection of early squamous lung cancer, the natural history of preinvasive lesions and whether biomarkers can be used to predict progression to cancer. Finally we will review the staging and management of preinvasive lung cancer lesions and the different therapeutic modalities that are available.

[Combination of narrow-band imaging and autofluorescence imaging videobronchoscopy in the assessment of lung cancer]

背景与目的

窄带成像（narrow-band imaging, NBI）与自荧光成像（autofluorescence imaging, AFI）是近几年临床诊断肺癌的支气管镜新技术。本研究旨在研究这两种技术的结合是否能提高肺癌诊断的敏感性和特异性。

方法

该项目共纳入137例疑似肺癌患者，所有患者的检查均基于Olympus Evis Lucera电子支气管镜系统，依次进行白光支气管镜（white light bronchoscopy, WLB）、窄带成像、自荧光成像检查，在每位患者镜下异常部位至少取3块组织送检。

结果

WLB的敏感性、特异性分别为56.6%和62.5%；NBI成像的敏感性、特异性分别为71.3%和75.0%；AFI敏感性、特异性分别为82.2%和25.0%；NBI联合AFI的敏感性、特异性分别为94.6%和87.5%。NBI+AFI与AFI相比，两者敏感性及特异性均有统计学差异（P < 0.01），与单用NBI相比，两者敏感性及特异性亦有统计学差异（P < 0.05）。

结论

NBI或AFI比WLB在肺癌诊断方面具有更好的敏感性，且联合使用NBI+AFI比其它任何一种单用技术具有更高的敏感性和特异性优势。

Early lung cancer: methods for detection

Early detection and surgical resection are essential for the treatment of lung cancer. It would be ideal to be able to detect and treat preinvasive bronchial lesions, defined as dysplasia and carcinoma in situ before progressing to invasive cancer. Advanced airway-assessment techniques have opened an avenue for early detection and surveillance of endobronchial malignancy. This article reviews currently available advanced imaging techniques for early detection of lung cancer, including autofluorescence bronchoscopy, narrow-band imaging, high-magnification bronchovideoscopy, endobronchial ultrasonography, and optical coherence tomography. Also discussed are the more recently developed endocytoscopy system and confocal fluorescence microendoscopy, currently used only for research purposes.

Relation between vascular patterns visualized by Narrow Band Imaging (NBI) videobronchoscopy and histological type of lung cancer

Narrow Band Imaging (NBI) videobronchoscopy is a new technique for visualization of microvascular changes in bronchial mucosa. The primary aim of this study was to evaluate relation between vascular patterns visualized by NBI and histology of lung cancer. We prospectively evaluated 65 patients with suspected lung cancer scheduled for bronchoscopy. NBI followed conventional WL videobronchoscopy. After identification of endoscopically visible tumor, NBI was used to determine predominant type of pathological vascular pattern (dotted, tortuous, abrupt-ending blood vessels-Shibuya descriptors). All the lesions were biopsied and histologically confirmed. There were 81.5 % male and 18.5 % female patients evaluated in the study. Lung cancer was confirmed in all patients; 63.1 % were diagnosed with squamous cell lung cancer (SCC), 24.6 % had adenocarcinoma, 9.2 % had small-cell (SCLC) and 3.1 % large-cell lung cancer (LC). Dotted blood vessels were significantly (p < 0.000) associated with adenocarcinoma, identified in 68.4 % adenocarcinoma and 31.6 % SCC. Tortuous blood vessels were identified in 72 % SCC, 8 % adenocarcinoma, 12 % SCLC and 8 % of LC. Tortuous blood vessels were significantly (p < 0.000) associated with SCC. Abrupt-ending vessels were identified in 81 % SCC, 14.3 % SCLC and 4.8 % adenocarcinoma and were significantly associated (p < 0.000) with SCC. Dotted visual pattern of blood vessels identified during NBI videobronchoscopy is highly suggesting adenocarcinoma histology of lung cancer. Tortuous and abrupt-ending blood vessels visualized under NBI videobronchoscopy significantly suggest squamous cell histology of lung cancer. Large-scale studies should be designed in order to determine true relation between visual appearance and histology in lung cancer.

Diagnostic flexible bronchoscopy and accessory techniques

We reviewed the most important diagnostic procedures implemented by means of flexible bronchoscopy, including bronchoalveolar lavage, bronchial brushing and biopsy, transbronchial lung biopsy and transbronchial needle aspiration. We reviewed the tools, techniques and potential complications of this examination.

Non-invasive measurement of the microvascular properties of non-dysplastic and dysplastic oral leukoplakias by use of optical spectroscopy

Differential Path-length Spectroscopy (DPS) was used to non-invasively determine the optical properties of oral leukoplakias in vivo. DPS yields information on microvascular parameters such as the mucosal blood content, the microvascular blood oxygenation and the average micro-vessel diameter as well as on tissue morphological parameters such as the scattering slope and scattering amplitude. DPS measurements were made on non-dysplastic and dysplastic oral leukoplakias using a novel fiber-optic probe, and were correlated to the histological outcome of biopsies taken from the same location. Our data show borderline significant increases in mucosal blood content in dysplastic lesions compared to non-dysplastic lesions, with no changes in microvascular oxygen saturation and light scattering signatures. These results suggest that dysplastic and non-dysplastic leukoplakias may be discriminated non-invasively in vivo through differences in their microvascular properties, if they can be reproducibly quantified in the presence of a variable thickness keratin layer that optically shields the mucosal layer.

Increased microcirculation in subepithelial invasion of lung cancer

BACKGROUND AND OBJECTIVE

Mucosal irregularity and hypervascularity associated with primary lung cancer in large airways are observed by bronchoscopy. The aim of this study was to evaluate microcirculation at subepithelial invasion sites of lung cancer.

METHODS AND PATIENTS

Between July 2001 and June 2007, 12 patients who had subepithelial invasion sites of lung cancer in the large airways (aged 52 to 74 years, 12 males) were enrolled into this study. They were 6 patients with adenocarcinoma, 4 patients with squamous cell carcinoma, and 2 patients with small cell carcinoma. We compared 12 control subjects without endobronchial abnormality (aged 51 to 83 years, 9 males and 3 females). The patients underwent conventional bronchoscopy and subsequent high magnification bronchovideoscopy with the conventional imaging and the narrow band imaging (NBI). For evaluating microcirculation of subepithelial invasion, hemoglobin index was calculated.

RESULTS

In high magnification view, aberrant microvessels and/or irregular mucosal thickening were observed at subepithelial invasion sites of lung cancer. Irregularly enlarged microvessels were increased and formed an aberrant microvessel network on the surface of irregular mucosa. The diameter of aberrant microvessels was significantly increased compared to normal microvessels. By switching to NBI, the aberrant microvessels were more clearly visualized. The levels of hemoglobin index were significantly higher in subepithelial invasion sites of lung cancer compared to normal mucosa.

CONCLUSION

In subepithelial invasion of lung cancer, aberrant microvessels are thought to be characteristic and subepithelial microcirculation may be increased.

Visible light optical spectroscopy is sensitive to neovascularization in the dysplastic cervix

Neovascularization in cervical intraepithelial neoplasia (CIN) is studied because it is the precursor to the third most common female cancer worldwide. Diffuse reflectance from 450-600 nm was collected from 46 patients (76 sites) undergoing colposcopy at Duke University Medical Center. Total hemoglobin, derived using an inverse Monte Carlo model, significantly increased in CIN 2+ (N=12) versus CIN 1 (N=16) and normal tissues (N=48) combined with P<0.004. Immunohistochemistry using monoclonal anti-CD34 was used to quantify microvessel density to validate the increased hemoglobin content. Biopsies from 51 sites were stained, and up to three hot spots per slide were selected for microvessel quantification by two observers. Similar to the optical study results, microvessel density was significantly increased in CIN 2+ (N=16) versus CIN 1 (N=21) and normal tissue (N=14) combined with P<0.007. Total vessel density, however, was not significantly associated with dysplastic grade. Hence, our quantitative optical spectroscopy system is primarily sensitive to dysplastic neovascularization immediately beneath the basement membrane, with minimal confounding from vascularity inherent in the normal stromal environment. This tool could have potential for in vivo applications in screening for cervical cancer, prognostics, and monitoring of antiangiogenic effects in chemoprevention therapies.

High-magnification vascular imaging to reject false-positive sites in situ during Hexvix® fluorescence cystoscopy

Fluorescence imaging for detection of non-muscle-invasive bladder cancer is based on the selective production and accumulation of fluorescing porphyrins-mainly, protoporphyrin IX-in cancerous tissues after the instillation of Hexvix®. Although the sensitivity of this procedure is very good, its specificity is somewhat limited due to fluorescence false-positive sites. Consequently, magnification cystoscopy has been investigated in order to discriminate false from true fluorescence positive findings. Both white-light and fluorescence modes are possible with the magnification cystoscope, allowing observation of the bladder wall with magnification ranging between 30× for standard observation and 650×. The optical zooming setup allows adjusting the magnification continuously in situ. In the high-magnification (HM) regime, the smallest diameter of the field of view is 600 microns and the resolution is 2.5 microns when in contact with the bladder wall. With this cystoscope, we characterized the superficial vascularization of the fluorescing sites in order to discriminate cancerous from noncancerous tissues. This procedure allowed us to establish a classification based on observed vascular patterns. Seventy-two patients subject to Hexvix® fluorescence cystoscopy were included in the study. Comparison of HM cystoscopy classification with histopathology results confirmed 32∕33 (97%) cancerous biopsies and rejected 17∕20 (85%) noncancerous lesions.

Interventional bronchoscopy from bench to bedside: new techniques for early lung cancer detection

Lung cancer is a leading cause of cancer-related death in the world, and it accounts for more deaths than breast, colon, and prostate cancer combined in the United States. From a historical perspective, the premise behind early lung cancer detection strategy is that early detection of lung cancer is justified if early treatment improves the outcome. New optical technologies such as those presented in this article allow dynamic study of these processes at the cellular level, and it is hoped that opportunities for targeted therapy will be provided in the future. Investigators are on the verge of discovering a multidimensional bronchoscopic platform that can be used to narrow in on airway structures, explore vascular flow and angiogenesis, and discover new features of bronchogenic carcinogenesis.

[Fluorescence cystoscopy. Perspective in clinical practice and research]

Many studies confirm the clinical interest of photodynamic diagnostics (PDD) in non-muscle invasive bladder cancer management. PDD or fluorescence cystoscopy is not only of great value in occult urothelial cancer detection, but may have a positive impact on disease-free survival and prognosis. Yet, its specificity is found to be highly variable between studies mainly in relation to different disease profiles. New imaging techniques aimed at enhancing visualization to assess the bladder wall are under development.

Autofluorescence bronchoscopy, a novel modality for the early detection of bronchial premalignant and malignant lesions

Lung cancer is the leading cause of cancer deaths in developed countries. Recently, autofluorescence bronchoscopy has been reported to improve the early detection of lung cancer in high-risk individuals. In the present study, we evaluated the efficacy of autofluorescence bronchoscopy for the early detection of bronchial premalignant and malignant lesions. From November 2000 through March 2004, 123 high-risk individuals (114 men and 9 women with a mean age of 68 years) were enrolled. Among 282 biopsy specimens, 93 (33.0%) were premalignant or malignant lesions. The sensitivity and negative predictive value for the detection of bronchial premalignant and malignant lesions were significantly higher with the addition of autofluorescence bronchoscopy than white light bronchoscopy alone. Moreover, the sensitivity for the detection of bronchial premalignant lesions was extremely higher with the addition of autofluorescence bronchoscopy than white light bronchoscopy alone, whereas there was no significant difference between autofluorescence bronchoscopy and white light bronchoscopy alone for the detection of non-malignant and malignant lesions. Autofluorescence bronchoscopy is a novel modality for the early detection of bronchial abnormality, especially for bronchial premalignant lesions.

Optimized autofluorescence bronchoscopy using additional backscattered red light

Autofluorescence bronchoscopy (AFB) has been shown to be a highly sensitive tool for the detection of early endobronchial cancers. When excited with blue-violet light, early neoplasia in the bronchi tend to show a decrease of autofluorescence in the green region of the spectrum and a relatively smaller decrease in the red region of the spectrum. Superposing the green foreground image and the red background image creates the resultant autofluorescence image. Our aim was to investigate whether the addition of backscattered red light to the tissue autofluorescence signal could improve the contrast between healthy and diseased tissue. We have performed a clinical study involving 41 lung cancers using modified autofluorescence bronchoscopy systems. The lesions were examined sequentially with conventional violet autofluorescence excitation (430 nm+/-30 nm) and violet autofluorescence excitation plus backscattered red light (430 nm+/-40 nm plus 665 nm+/-15 nm). The contrast between (pre-)neoplastic and healthy tissue was quantified with off-line image analysis. We observed a 2.7 times higher contrast when backscattered red light was added to the violet excitation. In addition, the image quality was improved in terms of the signal-to-noise ratio (SNR) with this spectral design.

Bronchial Intraepithelial Neoplasia/Early Central Airways Lung Cancer

BACKGROUND

An evidence-based approach is necessary for the localization and management of intraepithelial and microinvasive non-small cell lung cancer in the central airways.

METHODS

Material appropriate to this topic was obtained by literature search of a computerized database. Recommendations were developed by the writing committee and then reviewed by the entire guidelines panel. The final recommendations were made by the Chair and were voted on by the entire committee.

RESULTS

White light bronchoscopy has diagnostic limitations in the detection of microinvasive lesions. Autofluorescence bronchoscopy (AFB) is a technique that has been shown to be a sensitive method for detecting these lesions. In patients with moderate dysplasia or worse on sputum cytology and normal chest radiographic findings, bronchoscopy should be performed. If moderate/severe dysplasia or carcinoma in situ (CIS) is detected in the central airways, then bronchoscopic surveillance is recommended. The use of AFB is preferred if available. In a patient being considered for curative endobronchial therapy to treat microinvasive lesions, AFB is useful. A number of endobronchial techniques as therapeutic options are available for the management of CIS and can be recommended to patients with inoperable disease. In patients with operable disease, surgery remains the mainstay of treatment, although patients may be counseled about these techniques.

CONCLUSIONS

AFB is a useful tool for the localization of microinvasive neoplasia. A number of endobronchial techniques available for the curative treatment can be considered first-line therapy in inoperable cases. For operable cases, the techniques may be considered and discussed with the patients.

Non-invasive measurement of the morphology and physiology of oral mucosa by use of optical spectroscopy

Differential path-length spectroscopy (DPS) was used to non-invasively determine the superficial optical properties of oral mucosa in vivo. DPS yields information on physiological parameters such as the mucosal blood content, the microvascular blood oxygenation and the average micro-vessel diameter as well as on morphological parameters such as the scattering slope and scattering amplitude. DPS measurements were made on normal and cancerous oral mucosa using a novel fiber-optic probe, and were correlated to the histological outcome of punch biopsies taken from the same location. Our data shows that the mucosa of oral squamous cell carcinoma is characterised by a significant decrease in microvascular oxygenation and increase in mucosal blood content compared to normal oral mucosa as well as a significant decrease in scattering amplitude and increase in scattering slope.

The future of bronchoscopy in diagnosing, staging and treatment of lung cancer

Bronchoscopy is a central technique in diagnosing lung cancer, but also in different therapeutic approaches. A lot of techniques are available. The most common indication for bronchoscopy is for tissue sampling and determining the extent of lung cancer. Established diagnostic techniques are forceps biopsy, aspiration or brush cytology sampling, or needle aspiration. Laser therapy, electrocautery, cryotherapy and stenting are well-described techniques for the palliation of symptoms due to airway involvement in patients with advanced stages. Newer technologies, with an established role in clinical practice, are endobronchial ultrasound, autofluorescence bronchoscopy, and electromagnetic navigation. Other technologies, such as magnification, narrow-band imaging and confocal fluorescence microendoscopy, are in development for the use within the airways.

In vivo imaging of the bronchial wall microstructure using fibered confocal fluorescence microscopy

RATIONALE

Fibered confocal fluorescence microscopy (FCFM) is a new technique that produces microscopic imaging of a living tissue through a 1-mm fiberoptic probe that can be introduced into the working channel of the bronchoscope.

OBJECTIVES

To analyze the microscopic autofluorescence structure of normal and pathologic bronchial mucosae using FCFM during bronchoscopy.

METHODS

Bronchial FCFM and spectral analyses were performed at 488-nm excitation wavelength on two bronchial specimens ex vivo and in 29 individuals at high risk for lung cancer in vivo. Biopsies of in vivo FCFM-imaged areas were performed using autofluorescence bronchoscopy.

RESULTS

Ex vivo and in vivo microscopic and spectral analyses showed that the FCFM signal mainly originates from the elastin component of the basement membrane zone. Five distinct reproducible microscopic patterns were recognized in the normal areas from the trachea down to the more distal respiratory bronchi. In areas of the proximal airways not previously biopsied, one of these patterns was found in 30 of 30 normal epithelia, whereas alterations of the autofluorescence microstructure were observed in 19 of 22 metaplastic or dysplastic samples, five of five carcinomas in situ, and two of two invasive lesions. Disorganization of the fibered network could be found on 9 of 27 preinvasive lesions, compatible with early disruptions of the basement membrane zone. FCFM alterations were also observed in a tracheobronchomegaly syndrome and in a sarcoidosis case.

CONCLUSIONS

Endoscopic FCFM represents a minimally invasive method to study specific basement membrane alterations associated with premalignant bronchial lesions in vivo. The technique may also be useful to study the bronchial wall remodeling in nonmalignant chronic bronchial diseases.

Effective detection of bronchial preinvasive lesions by a new autofluorescence imaging bronchovideoscope system

Autofluorescence bronchoscopy is an important tool for the early detection of preinvasive bronchial lesions. However, autofluorescence bronchoscopy has difficulty distinguishing between preinvasive lesions and other benign epithelial changes. A new autofluorescence imaging bronchovideoscope system (AFI) comprises three signals, including an autofluorescence (460-690 nm) on excitation blue light (395-445 nm) and two different bands of reflected light: G' (550 nm) and R' (610 nm). We hypothesized that color analyses of these three wave lengths would improve our ability to differentiate between inflammation and preinvasive lesions. In order to prove this hypothesis and to evaluate the efficacy of AFI for detecting preinvasive lesions, we conducted a prospective study. A total of 32 patients with suspected or known lung cancer were entered into this study. Conventional white light bronchovideoscopy (WLB) and light induced fluorescence endoscopy (LIFE) were performed prior to using AFI. WLB and LIFE detected 62 lesions, including lung cancers (n=2), squamous dysplasias (n=30), and bronchitis (n=30). By utilizing AFI, 24 dysplasias and 2 cancer lesions were magenta in color, while 25 bronchitis lesions were blue. The sensitivities of detecting dysplasia by LIFE and AFI were 96.7% and 80%, respectively. The specificity of AFI (83.3%) was significantly higher than that of LIFE (36.6%) (p=0.0005). We conclude that AFI appears to represent a significant advance in distinguishing preinvasive and malignant lesions from bronchitis or hyperplasia under circumstances where LIFE would identify these all as abnormal lesions.

Narrow band imaging: a new diagnostic approach to visualize angiogenesis in superficial neoplasia

Although numerous gastrointestinal endoscopes pass through the oropharynx and the hypopharynx, it is extremely difficult to detect an early cancer in these sites during routine endoscopic examination. Most patients with cancer in these sites are usually diagnosed in advanced stages. If effective screening methods can detect an earlier stage, such as carcinoma in situ, it would obviously be of great benefit. Narrow band imaging is an innovative optical technology that can clearly visualize the microvascular structure of the organ surface. Herein, we demonstrate that narrow band imaging combined with magnifying endoscopy can identify a carcinoma in situ in oropharyngeal and hypopharyngeal mucosal lesions. Scattered irregular foci of microvascular proliferation projecting to the dysplastic squamous epithelium are the typical features. These results indicate that an approach to visualize angiogenesis or morphologic changes of microvessels in the superficial neoplasm can be a new diagnostic method not only for the head and neck region but also for other sites in the gastrointestinal tract.

Bronchoscopic imaging of pulmonary mucosal vasculature responses to inflammatory mediators

In current clinical practice, the initial stage in the detection of pulmonary airway disease is the clinician's interpretation of a bronchoscopy procedure. Due to the nature of this form of detection, diseases are often well advanced upon discovery. This paper proposes a new method for examining the pulmonary airway microcirculatory system via fluorescein imaging techniques similar to those used extensively in ophthalmology. Through the use of a specialized bronchoscopy imaging system we are able to successfully show that fluorescein emission detected in the rabbit trachea exhibits a clear response to inflammatory mediators and thus to changing local vascularity. The clinical implications of this technique are extensive including most importantly the potential use as an evaluation tool for pulmonary disease evaluation and likely other endoscopically accessible organs.

Measurement of hypoxia-related parameters in bronchial mucosa by use of optical spectroscopy

RATIONALE

Tumor hypoxia has both prognostic and therapeutic consequences for solid tumors. We developed a novel noninvasive technique, differential path-length spectroscopy (DPS), which allows the measurement of hypoxia-related parameters in the superficial microvasculature of tissue.

OBJECTIVES

The aim of this study was to measure the microvascular oxygenation of histologically normal endobronchial mucosa and of neoplastic lesions during bronchoscopy using DPS.

METHODS

Sixty-four patients with known or suspected malignancies of the lung were studied. One hundred and five endobronchial lesions (38 histologically normal, 37 metaplastic/mild dysplastic lesions, and 30 invasive carcinomas) were detected by white and/or autofluorescence bronchoscopy and measured using DPS.

RESULTS

We observed that bronchial tumors are characterized by a lower blood oxygen saturation and a higher blood content than normal mucosa. No differences were observed between normal and metaplastic/mild dysplastic mucosa.

CONCLUSION

DPS is a new optical technique allowing the noninvasive study of endobronchial tumor hypoxia.

A case of early-stage lung cancer detected by autofluorescence bronchoscopy

A 71-year-old man was referred to our hospital for further examination of abnormal sputum cytology. No abnormal nodular shadows were detected in chest X-ray and chest CT. The location of the tumor was clearly identified as a defect of autofluorescence by autofluorescence bronchoscopy at the bifurcation between the left B1+2 and B3 bronchi, whereas it was quite difficult by conventional bronchoscopy. Transbronchial biopsy revealed squamous cell carcinoma. Further examinations yielded the diagnosis of early-stage lung cancer. Photodynamic therapy was performed and complete response was confirmed. This case indicates the efficacy of autofluorescence bronchoscopy for detecting early-stage lung cancer.

Fluorescent bronchoscopy: contribution for lung cancer screening?

The majority of early lesions, even when centrally located, is missed by conventional white-light (WL) bronchoscopy. Fluorescent bronchoscopy is a promising tool in localising early malignant changes in the central airways, because it is significantly more sensitive than WL bronchoscopy. Originally, drug-induced fluorescence has been used, but today autofluorescence bronchoscopy is more common in relation to its simplicity and advantages. Different systems are available which yield comparable results. However, there are no studies comparing all systems. The disadvantage is the low specificity of the method. Fluorescent bronchoscopy will be more effective if carried out in high-risk patients and/or embedded in a program of preprocedural evaluation of sputum and together with a CT examination of the thorax. But a reduction of mortality as a result of such efforts has not been shown until the present time.

Spectroscopic studies of autofluorescence substances existing in human tissue: influences of lactic acid and porphyrins

The influence of lactic acid or porphyrins on the optical properties of tissue fluorophores is investigated by autofluorescence (AF) spectroscopy measurement with a GaN-based ultraviolet laser diode along with Fourier-transform IR (FTIR) spectroscopy measurement. As the lactic-acid concentration becomes dense, the AF peak intensity from elastin and desmosine solutions become wholly weak. A similar reduction in the AF intensity is observed for nicotinamide adenine dinucleotide (NADH) solutions. FTIR analysis indicates that the lactic acid causes the conformational change in elastin and the oxidation of NADH, which can be related to changes in the AF properties. The peak intensity of the tissue fluorophores also becomes weak when porphyrins are added, although the conformational change in each tissue fluorophore is not confirmed from FTIR analysis. Judging from the change in the scattering-light intensity of the excitation source, the observed change mainly originates from the absorption of the excitation source by porphyrins.

Real-time Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration of Mediastinal and Hilar Lymph Nodes

STUDY OBJECTIVES

Although various techniques are available for obtaining pathology specimens from the mediastinal lymph nodes, including conventional bronchoscopic transbronchial needle aspiration (TBNA), transesophageal ultrasonography-guided needle aspiration, and mediastinoscopy, there are limitations to these techniques, which include low yield, poor access, need for general anesthesia, or complications. To overcome these problems, we undertook the current study to evaluate the clinical utility of the newly developed ultrasound puncture bronchoscope to visualize and perform real-time TBNA of the mediastinal and hilar lymph nodes under direct endobronchial ultrasonography (EBUS) guidance.

DESIGN

Prospective patient enrollment.

SETTING

University teaching hospital.

PATIENTS

From March 2002 to September 2003, 70 patients were included in the study.

INTERVENTIONS

The new convex probe (CP) EBUS is integrated with a convex scanning probe on its tip with a separate working channel, thus permitting real-time EBUS-guided TBNA. The indications for CP-EBUS were the diagnosis of mediastinal and/or hilar lymphadenopathy for known or suspected malignancy. Lymph nodes and the surrounding vessels were first visualized with CP-EBUS using the Doppler mode. The dimensions of the lymph nodes were recorded, followed by real-time TBNA under direct EBUS guidance. Final diagnosis was based on cytology, surgical results, and/or clinical follow-up.

RESULTS

All lymph nodes that were detected on the chest CT scan could be visualized using CP-EBUS. In 70 patients, CP-EBUS-guided TBNA was performed to obtain samples from mediastinal lymph nodes (58 nodes) and hilar lymph nodes (12 nodes). The sensitivity, specificity, and accuracy of CP-EBUS-guided TBNA in distinguishing benign from malignant lymph nodes were 95.7%, 100%, and 97.1%, respectively. The procedure was uneventful, and there were no complications.

CONCLUSIONS

Real-time CP-EBUS-guided TBNA of mediastinal and hilar lymph nodes is a novel approach that is safe and has a good diagnostic yield. This new ultrasound puncture bronchoscope has an excellent potential for assisting in safe and accurate diagnostic interventional bronchoscopy.

In vivo measurement of the local optical properties of tissue by use of differential path-length spectroscopy

We demonstrate the capability of differential path-length spectroscopy (DPS) to determine the local optical properties of tissue in vivo. DPS measurements on bronchial mucosa are analyzed and yield information on the local blood oxygenation, blood content, average microvessel diameter, and wavelength dependence of the reduced scattering coefficient. Our data collected to date show that cancerous bronchial mucosa has a lower capillary oxygenation and a larger average capillary diameter than normal bronchial mucosa.

High magnification bronchovideoscopy combined with narrow band imaging could detect capillary loops of angiogenic squamous dysplasia in heavy smokers at high risk for lung cancer

BACKGROUND

We investigated the use of high magnification bronchovideoscopy combined with narrow band imaging (NBI) for the detailed examination of angiogenic squamous dysplasia (ASD). This was carried out in relation to bronchial vascular patterns with abnormal mucosal fluorescence in heavy smokers at high risk for lung cancer.

METHODS

Forty eight patients with sputum cytology specimens suspicious or positive for malignancy were entered into the study. Conventional white light and fluorescence bronchoscopic examination was first performed. Observations by high magnification bronchovideoscopy with conventional white light were made primarily at sites of abnormal fluorescence, and then repeated with NBI light to examine microvascular networks in the bronchial mucosa. Spectral features on the RGB (Red/Green/Blue) sequential videoscope system were changed from the conventional RGB broadband filter to the new NBI filter. The wavelength ranges of the new NBI filter were B1: 400-430 nm, B2: 420-470 nm, and G: 560-590 nm. ASD tissues were also examined using a confocal laser scanning microscope equipped with argon-krypton (488 nm) and argon (514 nm) laser sources.

RESULTS

The microvessels, vascular networks of various grades, and dotted vessels in ASD tissues were clearly observed in NBI-B1 images. Diameters of the dotted vessels visible on NBI-B1 images agreed with the diameters of ASD capillary blood vessels diagnosed by pathological examination. Capillary blood vessels were also clearly visualised by green fluorescence by confocal laser scanning microscopy. There was a significant association between the frequency of dotted vessels by NBI-B1 imaging and tissues confirmed as ASD pathologically (p=0.002).

CONCLUSIONS

High magnification bronchovideoscopy combined with NBI was useful in the detection of capillary blood vessels in ASD lesions at sites of abnormal fluorescence. This may enable the discrimination between ASD and another pre-invasive bronchial lesion.