A Prospective Study for Differential Diagnosis of Gastric Small Depressive Lesions By Narrow Band Imaging (NBI) Combined with Magnifying Endoscopy

Abstract

Background: The high-resolution endoscopy has increased opportunities of detecting small depressive lesion (SDL) in the stomach. However, accurate diagnosis of SDLs by conventional endoscopic examination has been difficult. Then, the number of biopsy specimen has increased to confirm the histological diagnosis. The following characteristic findings by a magnifying endoscopy are considered to be useful for differential diagnosis of neoplastic lesions; a clear demarcation line (DL) between the cancerous and non-cancerous area and an irregular microvascular pattern (IMVP). However, magnifying image by conventional white light image (WLI) is still difficult to diagnose SDLs correctly. Narrow band imaging (NBI) combined with magnifying endoscopy clearly enhanced the visualization of surface structure and microvascular architecture compared to conventional WLI, then, more accurate diagnosis of SDL is expected by NBI. Aims: The primary aim of this study was to compare the real-time diagnostic accuracy for gastric SDLs (<10 mm) between magnifying NBI and magnifying WLI. Subjects and Methods: Written informed consent was obtained from all the patients who receive routine endoscopic examination. Among them, patients in whom gastric SDLs were identified during the examination were enrolled, and examination with magnifying WLI followed by magnifying NBI for all SDLs was performed. Experienced endoscopists evaluated the visibility of DL and IMVP and classified them into 3 phases: visible, invisible or illegible. SDLs were diagnosed according to the combination of the visibility of DL and IMVP. The real-time diagnosis was used in this study. Diagnostic accuracy and time required for diagnosis in both methods were compared. Results: Total of 60 lesions of 56 patients were enrolled, but 3 lesions were excluded; one was not obtained biopsy specimen, one could not be examined sufficiently due to bleeding, one was not small (>10 mm). Finally, 57 lesions were analyzed in this study. Lesions were consisted of 30 cancers and 27 benign lesions. Diagnostic accuracy and sensitivity were 79% and 70% in NBI respectively. They were significantly higher than those of WLI (44%; p=0.0001, 33%; p=0.0005). Diagnostic specificity was higher with NBI (89%) than with WLI (67%), but it was not statistically significant. Time required for diagnosis was equivalent between two methods. Conclusion: To make accurate diagnosis for gastric SDLs, magnifying NBI is useful modality compared to conventional WLI. Both DL and IMVP are significant endoscopic findings to do it.