NBI (Narrow Band Imaging) was first introduced in the market in 2005 as a technique enabling to enhance image
contrast of capillaries on a mucosal surface(1). It is classified as an Optical-Digital Method for Image-Enhanced
Endoscopy(2). To date, the application has widely spread not only to gastrointestinal fields such as esophagus, stomach
and colon but also the organs such as bronchus and bladder. The main target tissue of NBI enhancement is capillaries.
However, findings of many clinical studies conducted by endoscopy physicians have revealed that NBI observation
enables to enhance more other structures in addition to capillaries. There is a close relationship between those enhanced
structures and histological microstructure of a tissue. This report introduces the tissue microstructures enhanced by NBI
and discusses the possibility of optimized illumination wavelength in observing living tissues.
We have developed the novel video endoscope imaging techniques; Narrow band imaging (NBI), Auto-Fluorescence Imaging (AFI), Infra-Red Imaging (IRI) and Endo-Cytoscopy System (ECS). The purpose of these imaging techniques is to emphasize the important tissue features associated with early stage of lesions. We have already launched the new medical endoscope system including NBI, AFI and IRI (EVIS LUCERA SPECTRUM, OLYMPUS MEDICAL SYSTEMS Co., Ltd., Fig.1). Moreover ECS, which has enough magnification to observe cell nuclei on a superficial
mucosa under methylene blue dye staining, is the endoscopic instrument with ultra-high optical zoom. In this paper we
demonstrate the concepts and the medical efficacy of each technology.
Here, we propose a new method to enhance the sensitivity of the reflectance spectrum to the scattering feature of the superficial tissue layer. This method is based on multiple discriminant analysis (MDA) in the eigen subspace of the spectrum. Considering the application of scattering imaging, we evaluated this method by performing multispectral imaging of two-layered tissue phantoms. A color map converted from the spectral reflectance well corresponds to variations in the size of the scatter in the first layer. In order to confirm our proposed method works well under more realistic conditions, we performed the computational simulations of the light propagation in the tissue. We used the simulation model combined with the Monte Carlo and the Mie scattering. Its conditions like the slab geometry and the particle distribution of the cell nucleus were estimated by the image measuring of pathological slices. Results on simulations show the possibility of enhancing the sensitivity of the reflectance spectrum to the scattering feature of the superficial tissue layer.
This study was performed to examine the usefulness of medical endoscopic imaging utilizing narrow-band illumination. The contrast between the vascular pattern and the adjacent mucosa of the underside of the human tongue was measured using five narrow-band illuminations and three broadband illuminations. The results demonstrate that the pathological features of a vascular pattern are dependent on the center wavelength and the bandwidth of illumination. By utilizing narrow-band illumination of 415±30 nm, the contrast of the capillary pattern in the superficial layer was markedly improved. This is an important benefit that is difficult to obtain with ordinary broadband illumination. The appearances of capillary patterns on color images were evaluated for three sets of filters. The narrow, band imaging (NBI) filter set (415±30 nm, 445±30 nm, 500±30 nm) was selected to achieve the preferred appearance of the vascular patterns for clinical tests. The results of clinical tests in colonoscopy and esophagoscopy indicated that NBI will be useful as a supporting method for observation of the endoscopic findings of early cancer.
We present the method which can calculate the spectral reflectance from physical parameters corresponding to the pathological features, e.g. average size of cell nuclei and standard deviation of cell nuclear size distribution, in consideration of multiple scattering in biological tissue. In this paper, the method combined the Monte Carlo method which simulates multiple scattering effects and the Mie theory which provides phase function (angular properties of light scattering) and scattering coefficient was employed. In order to investigate the validity of this method, the calculated spectra by the method and Monte Carlo method with Henyey-Greenstein phase functions were compared with measurement spectra derived from the tissue phantom whose size distribution has double peaks. From the results, it is shown that the method can better predict the spectral reflectance of tissue phantom rather than Monte Carlo method with Henyey-Greenstein phase function.
Conference Committee Involvement (4)
Design and Quality for Biomedical Technologies V
22 January 2012 | San Francisco, California, United States
Design and Quality for Biomedical Technologies IV
24 January 2011 | San Francisco, California, United States
Design and Quality for Biomedical Technologies III
25 January 2010 | San Francisco, California, United States
Design and Quality for Biomedical Technologies II
26 January 2009 | San Jose, California, United States