Accuracy of Computerised Tomography Scan for the Diagnosis of Lymph Node Metastasis in Cholangiocarcinoma

Abstract

Introduction: Lymph Node Metastasis (LNM) is the most unfavourable outcome and a criterion of inoperability in Cholangiocarcinoma (CCA). Computerised Tomography (CT) scans are commonly used for preoperative evaluation of LNM. However, the accuracy of CT scan in LNM detection has not been clearly evaluated. Aim: The aim of this study was to evaluate the accuracy of CT scan for preoperative LNM detection in CCA. Materials and Methods: This diagnostic test study was based on an ongoing prospective cohort study (Cholangiocarcinoma Screening and Care Program, CASCAP) in nine tertiary care hospitals in the Northeastern region of Thailand. The subjects were patients with suspected CCA based on ultrasound examination. CT scan was done to evaluate the lesion and LNM. For operable subjects, the lymph nodes were dissected and sent for pathological diagnosis. The results were then compared with the radiographic results. Results: The CT scan accurately detected the presence or absence of LNM in 78 of 127 CCA subjects (61.4%, 95% CI 52.4-69.9), resulting in a sensitivity of 50.8% (95% CI 37.9-63.6) and a specificity of 71.9% (95% CI 59.2-82.4). The positive and negative predictive values were 64.0% (95% CI: 49.2-77.1) and 59.7% (95% CI: 47.9-70.8), respectively. The positive likelihood ratio was 1.81 (95% CI: 1.14-2.86) and the negative likelihood ratio was 0.69 (95% CI: 0.51-0.92). Conclusion: The CT scan has limited accuracy in the preoperative diagnosis of LNM. Therefore, surgeons should be aware of the number of false positives in determining inoperable patients.

Keywords

• bile duct cancer
• preoperative
• radiographic diagnosis