Delayed-phase dynamic CT enhancement as a prognostic factor for mass-forming intrahepatic cholangiocarcinoma

Purpose: To retrospectively determine whether the degree of contrast material enhancement at delayed-phase dynamic computed tomography (CT) for intrahepatic cholangiocarcinoma (ICC) is related to the patient's prognosis after surgery. Materials and Methods: Neither institutional review board approval nor informed consent was required for this retrospective evaluation. Thirty-two patients (22 men, 10 women; mean age, 60.8 years; range, 33-80 years) with mass-forming ICC underwent dynamic CT. Delayed CT images obtained 4-6 minutes after the injection of contrast material were evaluated by two radiologists. Patients were classified in consensus into one of two groups: Group 1 included those in whom more than two thirds of the tumor showed enhancement on delayed-phase scans. Group 2 included those in whom less than two thirds of the tumor showed enhancement on delayed-phase scans. The imaging findings were correlated with pathologic findings. Survival curves were drawn by using the Kaplan-Meier method, and the differences between the groups were compared with the log-rank test. Multivariate analysis was performed to clarify prognostic factors. Results: There were 13 patients in group 1 and 19 in group 2. The degree of enhancement on the delayed-phase images showed statistically significant correlation with the amount of fibrous stroma (P < .001) and the frequency of perineural invasion (P < .01). The survival rate in group 1 was significantly lower than that in group 2 (P = .016). Multivariate analysis revealed that enhancement of more than two-thirds of the ICC was a significant and independent prognostic factor. Conclusion: The degree of enhancement on delayed-phase CT scans is a useful indicator for prediction of the prognosis of patients with mass-forming ICC.