Multidetector CT Versus ERCP for Preoperative Assessment of Longitudinal Extension of Distal Bile Duct Cancer

Accurate assessment of the longitudinal tumor extension is essential for determining the surgical strategy for distal bile duct cancer (DBDC). Although multidetector-row computed tomography (MDCT) is widely used for preoperative imaging, endoscopic retrograde cholangiopancreatography (ERCP) is still frequently performed despite its invasiveness. This study aimed to compare the diagnostic performance of MDCT and ERCP for assessing the longitudinal extension of DBDC.

Among 60 patients who underwent pancreatoduodenectomy for DBDC over an eight-year period, 43 patients who underwent both MDCT and ERCP before preoperative biliary drainage were retrospectively analyzed. According to the bile duct sections classification defined in the Anatomical Matters of the Regulations for the Management of Japanese Classification of Biliary Tract Carcinoma (the 2nd English Edition), the proximal margin of the longitudinal extension was independently evaluated based on MDCT and ERCP images. Imaging findings were compared with the pathological findings of the resected specimens.

The sensitivity, specificity, and accuracy of MDCT were 93.0%, 93.0%, and 86.0%, respectively. Those of ERCP were 92.1%, 76.9%, and 65.1%, respectively. Overestimation occurred in nine of 43 patients (20.9%) on ERCP alone, whereas no patients were overestimated on MDCT alone. In two patients with marked epithelial extension, it was underestimated on both MDCT and ERCP.

MDCT demonstrated higher diagnostic accuracy and a lower risk of overestimation than ERCP for assessing the longitudinal extension of DBDC. An MDCT-first approach may therefore be appropriate for routine preoperative assessment.