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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.