Techniques Using the Hemoglobin Index of the Gastric Mucosa

Abstract

ObjectivesColor changes seen at endoscopy are important for gastrointesti− nal endoscopic diagnosis. Quantification of the color information is useful for a scientific assessment of endoscopic color images. Since hemoglobin is the predominant pigment in the gastroin− testinal mucosa, measurement of the hemoglobin content is a reasonable method for quantifying the color in gastrointestinal endoscopic images. Recently, Tsuji et al. have developed a tech− nique for measuring mucosal hemoglobin content using electro− nic endoscopic imaging data [1]. The measure is called the "index of hemoglobin" (IHb). In this article, we describe the clinical ap− plications and the usefulness of the technique. Currently, the technique is being used for two main purposes: image analysis and image processing, as shown in Table 1. Basic PrinciplesElectronic Endoscopy System with Red, Green, and Blue Se− quential Imaging In order to calculate the IHb, an electronic endoscopy system that uses red, blue, and green (RGB) sequential imaging is neces− sary ( Figure 1) [2]. Briefly, when the RGB sequential videoscope is used, the gastrointestinal mucosa is illuminated with red, green, and blue light in turn, through a rotating RGB filter wheel. A monochromatic charge−coupled device (CCD) incorporated into the distal tip of the scope detects the light reflected from the mucosa as corresponding signals (V r for red light, V g for green, and V b for blue light) and this information is stored in the memory of the processor. A color image is constructed from the three sequential signals, V r , V g and V b , and it is displayed on the color monitor. Calculation of the IHbThe IHb is calculated from the values of the V r and V g signals, based on the following rationale [1]. Hemoglobin is the predomi− nant pigment in the gastrointestinal mucosa. The peak absorp− tion of light by hemoglobin occurs at a wavelength of 560 nm (which is within the wavelength range of the V g signal), while there is low absorption by hemoglobin around the wavelength 650 nm (which is within the V r range). Thus, if the mucosa is rich in hemoglobin content, absorption of light at a wavelength of 560 nm is large, that is, V g is low, whereas if the mucosa is less rich in hemoglobin content, then absorption at 560 nm is small, that is, V g is high. On the other hand, irrespective of the he− moglobin content, V r tends to be constant. Accordingly, the loga− rithmic transformation of the ratio of V r to V g leads to an index which is correlated to the hemoglobin content of the mucosa. The IHb is calculated using the equation: IHb = 32[log 2 (V r /V g )]Principle of the Adaptive IHb Color−Enhancement Technique [3] Enhancement of differences in color in the endoscopic image might help the endoscopist to identify the presence or extent of a flat lesion which shows only a slight color change. A structure− enhancement technique that has been incorporated into the EVIS240 and EVIS260 systems can demonstrate mucosal struc− tural change more clearly, but it is not suitable for enhancin...

Analysis of Endoscopic Electronic Image of Intramucosal Gastric Carcinoma Using a Software Program for Calculating Hemoglobin Index

“…This quantitative assessment has rarely been applied to the diagnosis of gastric cancer (4)(5)(6)(7). If the color changes that are seen endoscopically in intramucosal gastric carcinomas are actually derived from the mucosal vascularity of the carcinomatous tissue, then it could be assumed that the measurement of the mucosal hemoglobin content would be a useful marker for a quantitative assessment of the endoscopic color of gastric carcinoma.…”

Narrow-Band Imaging: Möglichkeiten und Grenzen

“…Digitale Rekonstruktionen von Video-Endoskopbildern ermöglichen die Bildbearbeitung [22]. Der Hämoglobingehalt in der Mukosa (der Hä-moglobin-Index) kann anhand der Farbe des reflektierten Lichts beurteilt werden [11,24,26]. Die neue Technik des Narrow-Band Imaging (NBI) kombiniert das Potenzial der Vergrößerungsendo-skopie mit dem der Bildbearbeitung [5 -7].…”

Supplementation of Los Angeles classification with esophageal mucosa index of hemoglobin can predict the treatment response of erosive reflux esophagitis

“…Applying an absolute value of the IHb, the detection of H. pylori infection in the stomach has been validated with high diagnostic sensitivity and specificity [18][19][20][21]. Besides differentiating benign from malignant gastric lesions [17,22,23], the IHb modality can correlate well with the severity of gastric mucosal inflammations, oxidative stress, and even levels of cytokines such as IL-8 [21,23]. In addition to its application in the stomach, several studies have suggested that the application of IHb modality can improve the detection of colon neoplastic lesions [24][25][26][27].…”