The diagnosis of intrahepatic peripheral cholangiocarcinoma by CT and MRI with the correlation of pathological findings

Objective To study the imaging features of intrahepatic peripheral cholangiocarcinoma (IHPCC) on the CT, MRI and the correlation of these features with histopathologic findings.Methods(Thirty-two) patients (17 males and 15 females) with pathologically proven IHPCC were reviewed retrospectively. CT conventional and dynamic enhancement scans were performed in 29 patients. MR imaging were obtained in five patients, and dynamic contrast-enhanced T 1-weighted imaging was performed in 2 cases.Results 24 lesions (75%) were located in the left lobe and 8 lesions (25%) in the right lobe. According to the pathological types, mass-type was found in 18 cases (56.3%), infiltrative-type in 7 cases (21.9%), and intracavitary-type in 4 cases (12.5%). In three patients the tumors were not definable at any imaging phase. The shape of tumor was circular, lobulated, or irregular, and the margins were clouding. No contrast enhancement (13 cases) or mild or moderate rim-like enhancement (8 cases) were the most frequent enhancement patterns observed in early stage. On the delay scan imaging, the center of the tumors showed mottling, reticular, or homogeneous hyperattenuating contrast enhancement. The tumor was consisted of fibrous tissue, tumor cells, and coagulative necrosis at the findings of histopathologic analysis. The content of these portions varied in different positions of tumors. At the edge of tumors, the main component was living tumor cells which was the pathological basis of early contrast enhancement. The delay contrast enhancement tended to be in the fibrosis, which mainly situated in the tumor center, because the contrast material entered the fibrosis very slowly but stagnated in it for long time.Conclusion Dynamic contrast enhancement scan was a very important technique for the correct diagnosis of IHPCC. The typical features of IHPCC include the hypodensity of hepatic lesion on precontrast scan, peripheral enhancement in the early stage, and tumor central enhancement on the delayed dynamic scan.