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Keywords:
Liver, Biliary Tract / Gallbladder, Gastrointestinal tract, MR, Contrast agent-intravenous, Neoplasia, Cancer
Authors:
G. Mamone, G. Marrone, G. Gentile, V. Carollo, M. Milazzo, A. Luca; Palermo/IT
DOI:
10.1594/ecr2015/C-2590
Conclusion
Intrahepatic or peripheral cholangiocarcinoma is an uncommon primary hepatic malignancy,
with increasing incidence worldwide [2].
In the literature,
some reports have described MRI of IMC [10,
11] but,
to the best of our knowledge,
there are few studies with descriptions of Gd-BOPTA MRI features relating to mass-forming cholangiocarcinoma,
and in particular only one large and extensive study of the hepatobiliary pattern has been published [4].
Though some suggestive features have been reported,
IMC is often difficult to differentiate from metastatic adenocarcinoma [12].
In our study we retrospectively evaluated the Gd-BOPTA MRI findings in 29 patients with IMCs,
focusing on the HBP pattern.
In our cases,
most of the IMCs (96%) showed hyperintense signal intensity rather than a homogeneous hypointense defect on HBP images,
caused by the presence of central hyperintense or isointense area that we call “cloud” of enhancement.
The pattern in the HBP phase is determined by the intracellular concentration of contrast material in hepatocytes.
Because there are no cells of hepatocytic origin in IMCs,
we should see the lesions as hypointense.
On the other hand,
the hyperintensity inside the lesions can be explained because IMCs show fibrotic stroma that retains contrast material in the extracellular space [6,13]. In our study,
the other interesting finding in the HBP was that most lesions (82%) showed a hypointense peripheral rim,
which we call “late rim”; this finding is likely correlated with the hypervascular peripheral rim in the arterial phase,
typical of IMC,
so its hypointensity corresponds to the greater density of viable and vascularized tumor cells,
which release the constrast medium in the HBP. In our study,
because late rim appeared only in association with cloud enhancement,
82% of IMCs had a “target pattern”.
The target appearance of IMCs on hepatobiliary phase images has been reported in only 5 studies with Gd-BOPTA MRI [4-8]; with the exception of the study of Jeon TY [4],
the other studies mention this pattern in the context of general imaging of hepatic lesions and in pictorial essays [5-8].
Though this finding on Gd-BOPTA MRI has not been explored extensively,
similar results were obtained in 5 studies with Gd-EOB-DTPA [14,
15]. Nevertheless,
metastases from adenocarcinoma tumors can show a target appearance because of their fibrous stromaThe target pattern is then suggestive of IMC,
but is not a specific finding.EndFragment On dynamic phases,
we found a peripheral enhancement with progressive and concentric filling of contrast material on delayed images,
described as typical of IMC. In summary,
at Gd-BOPTA MRI,
IMC is a large,
nonencapsulated lesion,
characterized by rim enhancement in the arterial phase,
with centripetal and/or gradual filling in delayed phases.
In delayed dynamic phases,
IMC can show a peripheral hypointense rim called “peripheral wash-out”. In the HBP,
all IMCs but one showed a “cloud” of enhancement or a “target pattern”.
Although these findings are not specific and may be encountered in other lesions such as metastases from adenocarcinoma,
they are suggestive of IMC and with association with other findings such as vascular encasement,
focal liver atrophy,
dilatation of intrahepatic bile ducts,
and lymphadenopathy,
may strengthen the diagnosis and help to differentiate between IMC and other lesions.