Narrow Band Imaging: Technology Basis and Research and Development History

Abstract

The first launch of narrow band imaging (NBI) was in 2005. Since then, in most countries where gastrointestinal endoscopies are performed, NBI is the most commonly used optical digital method of performing image-enhanced endoscopy. Thanks to the outstanding efforts of many endoscopists, many clinical studies have been performed and clinical evidence has been gathered. In Japan, since 2010, NBI has been reimbursed under the Japanese national health insurance system. This is owing to the establishment of clinical evidence by physicians. However, even though endoscope systems with NBI function have been widely used outside of Japan, dissemination of knowledge on how to use NBI is insufficient. In this review paper, the technology basis of NBI and its research and development history are described. I hope this information will be helpful for updating physicians’ knowledge of NBI.

Coherent Narrow-Band Light Source for Miniature Endoscopes

“…8(c) is attributed to lower illumination used and the threshold parameters chosen for the imaging processing software. Notably, as a technology for optical image contrast enhancement, NBI exploits the property of hemoglobin in the blood vessels to strongly absorb blue and green wavelengths, to further improve the visibility of the capillary blood vessels in the surface of mucosa [32]. In contrast to the conventional NBI imaging techniques that use optical filters to generate NBI light by eliminating all wavelengths except blue and green, the scheme presented here uses narrow band laser sources allowing to readily achieve NBI illumination conditions.…”

“…In addition, color-coding in spectral imaging can be paired to interested biological tissues to optimize contrast information. For instance, we have demonstrated the applicability of our endoscope for narrow band imaging (NBI) [32], [33], [34], which is another striking feature that makes it an excellent tool for high contrast imaging of blood vessels in mucosa.…”

Evidence based review of the impact of image enhanced endoscopy in the diagnosis of gastric disorders

“…Moreover, biological tissues behave differently at different wavelengths of light due to their characteristic patterns of absorption and scattering of light. Since haemoglobin molecule has two absorption peaks at 415 nm and 540 nm, the mucosal microvascular patterns are highlighted in extensive detail with NBI[34]. …”

“…At least five prospective studies have studied NBI using this approach[35-39]. In a prospective study on an unselected population, our group screened for focal gastric lesions using WLE followed by characterization of detected lesions by magnified NBI (M-NBI)[34]. Additional 15% lesions (mostly IM) were detected with M-NBI (Figure 4).…”

LED-Based Light Source Combined with Quantum Dot for Spectral Imaging

“…For example, narrow band imaging (NBI) and blue laser imaging (BLI), which are kinds of spectral imaging, are provided by the commercial manufacturers of endoscopes [10,11]. In NBI, which is well known to be clinically helpful, the light with the spectral bands near 410 and 540 nm illuminates tissues through the light guide [12]. In fluorescence imaging, the light of the excitation band of endogenous or exogenous fluorescent substances illuminates tissues in order to induce the emission of the light shifted to the higher wavelength [13].…”