A Novel Chromoendoscopic Method By Using Acetic Acid-Indigo Carmine Mixture (AIM) for Diagnosis of Early Gastric Cancers

Abstract

Background: Recent advances in endoscopic imaging technology have enabled the visualization of early-stage cancer and its precursors in the gastrointestinal tract. Magnifying endoscopy, high-resolution endoscopy, narrow-band imaging system, auto fluorescence imaging system, and various combinations of these technologies, are all important for the recognition of small and unclear lesions. However, these technologies are uncommon and require special equipment. Recently, we have introduced a new chromoendoscopic method by using acetic acid- indigo carmine mixture (AIM) for diagnosis of early gastric cancers (EGC). Patient and Methods: This was a case series study. The setting was a pretreatment examination at our hospital. 23 patients with EGCs were included in the study. The extent of the tumors was diagnosed by white light, standard chromoendoscopic observations, and AIM chromoendoscopic observations. The main outcome measurement was the diagnostic accuracy of each observation in relation to the histological mapping as a criterion standard. Results: A volume of 20-40 ml of AIM that is freshly prepared acetic acid solution (0.75-1.5%) with indigo carmine (0.1-0.4%) is instilled into the stomach through the working channel of the endoscope. Within a few minutes enhanced surface architecture appears, and EGCs were observed as red or yellow areas in a blue background. Of the 23 EGCs, diagnostic accuracy of white light, standard chromoendoscopic observations, and AIM chromoendoscopic observations were 45%, 87%, and 96%, respectively. By using AIM method, no accidental symptom occurred. Discussion: Indigo carmine is not absorbed into cells (contrast stain), highlights crypts and folds (mucosal pattern). Acetic acid breaks disulfide bonds of mucus, improving mucosal detail of epithelial surface. The combinations of these mechanisms at the same time could achieve the very clear enhanced visualization of EGCs. Conclusions: This new chromoendoscopic method can be used to identify small cancer foci and delineate the margin of EGCs easily, safely, and inexpensively.