To investigate the MRI enhancement features and differential diagnosis of small intrahepatic cholangiocarcinoma (ICC) combined with liver cirrhosis.

A total of 56 patients with small ICC combined with liver cirrhosis who underwent surgical treatment in the Eastern Hepatobiliary Surgery Hospital Affiliated to the Second Military Medical University between December 2012 and December 2015 were enrolled in this prospective cohort study. Among them, 40 cases were male and 16 were female, age 29-74 years old with a median age of 54 years old. The informed consents of all patients were obtained and the local ethical committee approval was received. All the patient underwent hepatic dynamic enhanced MRI examination and intravenous injection of Gd-DTPA contrast. The enhanced MRI imaging included hepatic arterial phase, portal vein phase and delayed phase. Inter-observer consistency of determining enhancement types was assessed by kappa coefficient. Correlation between enhancement type and lesion diameter was analyzed by Fisher's exact probability test.

The inter-observer consistency of determing lesion enhancement types was excellent (κ=0.82). 52%(29/56) of the patients with small ICC presented as progressive enhancement pattern, 36%(20/56) as stable pattern, 5%(3/56) as fast-in and fast-out pattern and 7%(4/56) as fast-in + recession pattern. The most common enhancement pattern for the lesions with a diameter of less than 20 mm was stable pattern, and progressive pattern for the lesions with a diameter of 20-30 mm. The enhancement pattern of small ICC was correlated with the diameter of lesion (P=0.006).

Most common MRI enhancement pattern for the patients with small ICC combined with liver cirrhosis are stable and progressive pattern. But some presents as fast-in and fast-out pattern, and this pattern is similar to that of small hepatocellular carcinoma, which is the key and difficult point for differential diagnosis between them.