Narrow band imaging with high-resolution bronchovideoscopy: A new approach for visualizing angiogenesis in squamous cell carcinoma of the lung
Introduction
Narrow band imaging (NBI) is a new optical technology of modified white light using special blue and green light that can clearly visualize microvascular structures in the mucosal layer [1], [2]. NBI is now classified as an image enhanced endoscopy (IEE) technology and is available to the entire field of endoscopy combined with conventional white light instruments [3], [4]. The advantage of NBI over other techniques is its ability to enhance fine superficial microvessel patterns [5], [6]. Since the development of NBI, some investigators have reported that this new technology can provide clear images of vascular structures in some organs especially the GI tract [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17]. NBI may also allow for better detection of early preneoplastic and neoplastic mucosal lesions and may improve the effectiveness of endoscopic surveillance and screening. Moreover, in the field of bronchovideoscopy, we have also reported that high magnification bronchovideoscopy combined with NBI was useful for detecting capillary blood vessels in angiogenic squamous dysplasia (ASD) lesions [13]. Using high magnification bronchovideoscopy combined with NBI, increased vessel growth and complex networks of tortuous vessels, in addition to several dotted vessels, were identified in dysplastic mucosa or angiogenic dysplastic mucosa.
Angiogenesis that is essential for tumor growth was first recognized by Folkman [18], [19]. In order to progress to a larger size, incipient neoplasia must develop angiogenic capabilities. Several studies investigating the multi-step model of carcinogenesis in epithelial tumors have shown that angiogenesis is required, in addition to molecular changes [20]. An angiogenic switch appears to occur in pre-invasive lesions prior to invasive tumor formation in transgenic mouse models and human cancer pathogenesis studies [21], [22]. However, except for a few studies, these studies were done on tissue sections retrospectively obtained from surgical or biopsied specimens. In vivo investigations to evaluate tumor angiogenesis during multi-step carcinogenesis is desirable for diagnostic efficacy.
In a previous study, we showed angiogenesis only in bronchial dysplastic lesions using high magnification bronchovideoscopy combined with NBI at sites of abnormal fluorescence established by fluorescence bronchoscopy [13]. In the present study, we investigated the ability of a high-resolution bronchovideoscopy system with NBI to detect and visualize blood vessel structures in squamous cell carcinoma of the bronchi, including carcinoma in situ (CIS), microinvasive carcinoma and invasive carcinoma, as well as dysplastic bronchial epithelium, including ASD lesions, without using fluorescence bronchoscopy.
Section snippets
Narrow band imaging
The conventional RGB sequential videoscope system has a xenon lamp and rotation disk with 3 RGB optical filters. The rotation disk and monochrome CCD are synchronised and three band images are generated sequentially. Colour images can be synthesised using three band images with the video processor. Narrow band imaging, developed in conjunction with the Olympus Optical Corp., Tokyo, Japan, is a novel system that can be used to observe microvessel structure using a new narrow band filter on an
Pathological diagnosis of biopsy specimens
Biopsy specimens from abnormal sites were diagnosed as 37 bronchial squamous dysplasias including 22 ASD, 5 CIS, 5 microinvasive carcinomas and 14 invasive squamous cell carcinomas. Two laryngeal carcinomas in situ and one laryngeal invasive carcinoma were also diagnosed in the same session.
High-resolution bronchovideoscopic white light image and the corresponding NBI image
Fig. 2A shows high-resolution bronchoscopic findings with white light and NBI at the bifurcation of Rt B6 and the basal bronchus of a patient with sputum cytology suspicious for malignancy. Increased vessel
Discussion
NBI is now classified as an IEE technology, that can be divided into two categories, dye-based IEE and equipment-based IEE [4]. Optical and electronic technology have both been enabled in equipment-based IEE, which was applied to NBI, or spectral estimation technology and surface enhancement. NBI technologies have been well evaluated and established in the field of gastrointestinal endoscopy and applied to detailed inspections for pathological diagnosis. Recently, there are some reports
Conflict of interest
All authors have none declared.
Funding
Supported, in part, by Grant-in-Aid for Scientific Research (C) 18591541 from Japan Society for the Promotion of Science to Kiyoshi Shibuya.
Acknowledgements
We wish to thank K. Gono, T. Takigawa and S. Takehana (Olympus Optical Corp., Tokyo, Japan) for their technical assistance.
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2020, Thoracic Surgery ClinicsCitation Excerpt :A key aspect to consider, however, is that AFB has a lower specificity than WLB because nonspecific airway changes often also can lead to abnormal fluorescence.38 Narrow band imaging (NBI) demonstrates similar advantages and is helpful in detecting changes, such as vessel growth, tortuosity, and microvascular patterns associated with angiogenesis, which develop during early phases of premalignant disease (see Fig. 5).39,40 This is achieved through emission of blue light and green light bandwidths.
Early Lung Cancer Detection
2018, Clinics in Chest MedicineCitation Excerpt :Angiogenic squamous dysplasia tissues have been examined by using a confocal laser scanning microscope equipped with argon-krypton (488 nm) and argon (514 nm) laser sources. NBI enables detection of onset of angiogenesis during multistep carcinogenesis of the lung.19 These new bronchoscopic modalities have improved screening and detection of early lung cancer of the central airway, especially squamous cell carcinoma in situ.
Preinvasive disease of the airway
2017, Cancer Treatment ReviewsCitation Excerpt :The bronchoscope emits light of two specific wavelengths, which are strongly absorbed by haemoglobin. This technique can detect increased vessel growth, tortuosity, and microvascular patterns in both the superficial and deeper layers of the epithelium [49]. It is potentially useful for detection of preinvasive disease as angiogenesis has been shown to occur early on in these lesions [50].