Diffusion-Weighted Magnetic Resonance Imaging for the Diagnosis of Lymph Node Metastasis in Patients with Biliary Tract Cancer

Objective: The diagnostic efficacy of the apparent diffusion coefficient (ADC) on diffusion-weighted magnetic resonance imaging for lymph node metastasis in biliary tract cancer was investigated in the present study. Methods: Surgically resected 112 lymph nodes from 35 biliary tract cancer (BTC) patients were examined in this study. Values of the ADC mean and minimum of lymph nodes, as well as short-axis and long-axis diameters of lymph nodes were assessed by computed tomography (CT). The relationship between these parameters and the presence of histological lymph node metastasis was evaluated. Results: Histological lymph node metastasis was detected in 31 (27.7%) out of 112 lymph nodes. The short-axis diameter in metastatic lymph nodes was significantly larger than that in non-metastatic lymph nodes (P = 0.002), but the long-axis diameter was not significantly different between metastatic and non-metastatic lymph nodes. Both ADC mean and minimum values in metastatic lymph nodes were significantly lower than those in non-metastatic lymph nodes (P < 0.001, respectively). However, the ADC minimum value showed the highest accuracy for the diagnosis of histological lymph node metastasis, with an area under the curve of 0.877, sensitivity of 87.1%, specificity of 82.7%, and accuracy of 83.9%. Conclusions: The ADC minimum value on diffusion-weighted magnetic resonance imaging was very useful for the diagnosis of lymph node metastasis in BTC.