Implication of lymph node metastasis detected on ¹⁸F-FDG PET/CT for surgical planning in patients with peripheral intrahepatic cholangiocarcinoma

OBJECTIVES: Intrahepatic cholangiocarcinoma (ICC) is the second most common primary hepatic malignancy after hepatocellular carcinoma. ICC can be divided into 2 types according to their location: peripheral and hilar types. Intense ¹⁸F-FDG uptake on PET was reported in peripheral ICC. However, the usefulness of PET/CT in detecting tumors and predicting prognosis in peripheral ICC has not been fully evaluated. In this study, we evaluated the clinical role of ¹⁸F-FDG PET/CT to predict the recurrence after the curative resection in patients with surgically indicated peripheral ICC. METHODS: Eighteen patients with ICC underwent preoperative CT and ¹⁸F-FDG PET/CT scans. SUV_max of tumor, tumor to normal liver SUV ratio (TNR), lymph node status evaluated by ¹⁸F-FDG PET/CT, tumor and lymph node size measured by CT, vascular invasion confirmed by pathology, and satellite nodules found on CT were compared between 1-year recurrence group and recurrence-free group by chi-square test. RESULTS: Of total 23 measurable lymph nodes, 4 nodes were positive and other 19 nodes were negative or equivocal on CT. Among those 23 nodes, 9 nodes were positive and other 14 nodes were negative on ¹⁸F-FDG PET/CT. The sensitivity and specificity of CT were 20.0% and 86.4%, and those of ¹⁸F-FDG PET/CT were 80.0% and 92.3%. In the comparison between 1-year recurrent and nonrecurrent groups, lymph node metastasis detected on F-FDG PET/CT had statistically positive correlation with the 1-year recurrence after surgical resection (P = 0.02). Other factors showed no statistically significant difference between the groups. CONCLUSION: We found that lymph node metastasis detected on ¹⁸F-FDG PET/CT correlated positively with 1-year recurrence after surgical resection in patients with peripheral ICC.