Preoperative Diagnosis of Lymph Node Metastasis of Perihilar Cholangiocarcinoma Using Diffusion-Weighted Magnetic Resonance Imaging

Introduction Although the prognosis of patients with resected perihilar cholangiocarcinoma (PHC) with histological lymph node metastasis (LNM) is poor, preoperative prediction of LNM is difficult. This study aimed to evaluate the diagnostic performance of diffusion-weighted magnetic resonance imaging (DWI) for LNM of PHC. Method Consecutive patients who underwent surgical resection of PHC between January 2012 and May 2020 were retrospectively reviewed. The lymph node (LN) area (mm 2 ) and apparent diffusion coefficient (ADC) value ( × 10 −3 mm 2 /s) of pericholedochal LNs were measured by DWI. The characteristics of the patients and the LNs were evaluated according to the histological presence or absence of regional LNM. Univariate and multivariate analyses were performed to identify the predictors of LNM of PHC. Results Of the 93 eligible patients, 49 (53%) were LNM positive and 44 (47%) were LNM negative. Although the characteristics of the patients were similar between the two groups, the mean ADC value was significantly lower in the LNM positive group than in the LNM negative group. On multivariate analysis, mean ADC value ≤1.80 × 10 −3 mm 2 /s was independently associated with LNM of PHC (risk ratio: 12.5, 95% confidence interval: 3.05–51.4; p = 0.0004). The sensitivity, specificity and accuracy of mean ADC values ≤ 1.80 × 10 −3 mm 2 /s for predicting LNM of PHC were 94%, 55% and 75%, respectively. Conclusions DWI might be useful for the preoperative diagnosis of LNM of PHC.