Intrahepatic mass-forming cholangiocarcinoma: enhancement pattern on Gd-BOPTA-MRI with emphasis of hepatobiliary phase

Purpose: To describe the Gd-BOPTA MRI findings of intrahepatic mass-forming type cholangiocarcinomas (IMCs), with emphasis on the hepatobiliary phase (HBP). Methods: We reviewed retrospectively 29 IMC patients who underwent Gd-BOPTA-MRI between June, 2004 and June, 2014. Images were acquired prior to, and after, administration of 15–20 mL of Gd-BOPTA in the dynamic phase (arterial phase, portal venous phase, and 3–5 min phase), 10–15-min late phase, and 2–3 h HBP phase. Results: In the dynamic phase, 27 (93%) lesions showed a peripheral rim-like enhancement in the arterial and portal venous phases, followed by progressive filling-in on the delayed images. In 14 (56%) cases, a hypointense peripheral rim was identified in the 10–15-min late phase, delineating a target pattern. In the HBP, the cholangiocarcinoma showed a diffuse, mainly central and inhomogeneous enhancement (cloud of enhancement) in 28 (96%) patients; in 23 (79%) cases, there was an association between cloud appearance and a hypointense peripheral rim, showing a target pattern. Conclusions: Gd-BOPTA MRI pattern of IMC on dynamic study is similar to that of conventional extracellular agents, that is peripheral enhancement with progressive and concentric filling of contrast material on delayed phases. At 10–15 min delayed phases, IMC shows often a peripheral hypointense rim consistent with a target appearance. In the HBP, due to progressive central enhancement (cloud) and peripheral hypointense rim, an higher number of tumors show a target appearance; this pattern is not specific and would also be expected to be seen in metastases from adenocarcinoma.