Imaging features of intrahepatic cholangiocarcinoma in Gd-EOB-DTPA-enhanced MRI.

OBJECTIVE: The aim of this study is to describe the imaging features of intrahepatic cholangiocarcinoma in Gd-EOB-DTPA-enhanced MRI and to determine whether it results in improved tumour conspicuity of cholangiocarcinoma.
MATERIALS AND METHODS: Fifty-four patients with histologically proven intrahepatic cholangiocarcinoma underwent MRI of the liver using a 1.5T MR-scanner with Gadoxetic acid disodium (Gd-EOB-DTPA; Eovist/Primovist, Bayer Healthcare, Berlin, Germany). The standard imaging protocol included a T2w multi-shot TSE sequence with fat saturation (fs), a T2w single shot sequence without fs and a T1w 3D GRE sequences with fs (unenhanced and arterial, portovenous, late venous and hepatobiliary phase). Two board certified radiologists experienced in liver MRI (5 and 10 years experience) evaluated retrospectively all MRI scans qualitatively and quantitatively. Signal was measured with region-of-interests (ROI) and signal-to-noise (SNR) as well as contrast-to-noise (CNR) was calculated. Statistical significance was tested with an ANOVA and a pairwise Wilcoxon rank test.
RESULTS: All intrahepatic cholangiocarcinomas presented as hypointense lesions in the late venous and hepatobiliary phase. Images in the hepatobiliary phase showed the highest lesion conspicuity, i.e. n=9 blurred (16.6%), n=31 moderate (57.4%) and n=14 sharp (26%). This was significantly higher than the lesion conspicuity of all other sequences or phases. Furthermore, the CNR was the highest in this sequence with 76.8±51.3, with significantly higher values than the CNR of the unenhanced T1w sequence (CNR: 35.6±21.0; p<0.0001) and the arterial phase images (CNR: 53.6±36.8; p<0.001). The hepatobiliary phase images showed a SNR of 97.3±59.7 (p<0.001) and thus was significantly different from the unenhanced T1w sequence (SNR: 60.4±35.3; p<0.001), whereas the increase in SNR from the late venous to hepatobiliary phase was neglectable, indicating that no liver-specific contrast uptake is present in cholangiocarcinoma.
CONCLUSION: Intrahepatic cholangiocarcinoma presents as a hypointense lesion in Gd-EOB-DTPA-enhanced MRI in late venous phase images. The lesion conspicuity as well as CNR was highest in the hepatobiliary phase. Consequently, hepatobiliary phase images in Gd-EOB-DTPA-enhanced MRI images might be helpful for therapy planning due to the exact depiction of the tumour borders.