Specific diagnosis of biliary strictures by quantitative assessment using a cholangioscopically derived hemoglobin index

Background: We used percutaneous transhepatic cholangioscopy for detailed assessment of biliary tumors. Among the most important endoscopic findings is greater mucosal vascularity in malignant than in benign biliary strictures. Development of digital image processing now permits measurement of mucosal hemoglobin volume as a hemoglobin index. We studied the clinical usefulness of this hemoglobin index for differentiating malignant from benign biliary strictures. Methods: From 2000 to 2002 we determined the hemoglobin index in 22 patients with biliary stricture (8 with bile duct carcinoma; 1 with carcinoma of the duodenum; 5 with pancreatic carcinoma and 8 with benign stricture). Eight patients with malignant stricture were diagnosed by the histological examinations of resected specimens; six with malignant stricture and eight with benign stricture were diagnosed by examination of biopsy specimens. The ratio of hemoglobin indices in a given patient of lesional and uninvolved mucosa was determined from cholangioscopic imaging data. Results: The mean hemoglobin index ratio for bile duct carcinoma was 1.83; for carcinoma of the duodenum 1.98; and for pancreatic carcinoma, 1.35. For benign strictures, the ratio was only 1.09. The mean hemoglobin index ratio in patients with bile duct or pancreatic carcinoma was significantly higher than in patients with benign stricture (P < 0.05, paired t-test). Conclusions: An image-derived hemoglobin index is useful for diagnostic assessment of biliary stricture.