Imaging prediction of lymph node metastasis and early recurrence in patients with distal cholangiocarcinoma

Lymph node (LN) metastasis is one of the significant prognostic factors after pancreaticoduodenectomy (PD) for distal cholangiocarcinoma (DCC). Upper abdominal enhanced computed tomography (CT) scan is a routine examination for patients with DCC; however, the predicted value of its imaging features for LN metastasis has not been sufficiently assessed. Furthermore, there is a lack of widely accepted standards in imaging features that can accurately predict LN metastasis and early recurrence (ER). This study aimed to investigate the values of regional LNs imaging features in predicting LN metastasis and ER in patients with DCC.

All patients who underwent PD for DCC in Beijing Tsinghua Changgung Hospital were retrospectively identified. Their clinical documentation, pathological results, and imaging features of regional LNs on preoperative abdominal enhanced CT images were reviewed.

Of 61 DCC patients, 19 (31.1%) experienced ER. Patients who experienced ER had significantly higher percentage of pancreatic invasion, and peri-pancreas LN metastasis than patients who did not (P=0.045 and 0.03, respectively). Patients who had peri-pancreas LN metastasis showed significantly higher percentages in the following imaging features: at least 1 LN with short-axis diameter ≥10 mm, at least 2 LNs with short-axis diameter ≥8 mm, and at least 3 LNs with short-axis diameter ≥6 mm than patients who did not (P=0.04, 0.02, and 0.003, respectively). Among these imaging features, at least 3 LNs with short-axis diameter ≥6 mm (P=0.03) was found to be independent ones to predict peri-pancreatic LN metastasis. Moreover, the imaging feature of at least 3 LNs with short-axis diameter ≥6 mm had better performance on predicting LN metastasis in sensitivity (50.0%), specificity (85.4%), positive predictive value (62.5%), negative predictive value (77.8%), and accuracy (73.8%) than the commonly used diagnosing criteria for LN metastasis of at least 1 LN with short-axis diameter ≥10 mm or central necrosis in LN.

The imaging feature of at least 3 LNs with short-axis diameter ≥6 mm could predict LN metastasis with high specificity, and provide a clue for predicting ER after PD in patients with DCC.