Diagnostic Tools and Clinical Pathology

MR signal intensity changes in hepatic parenchyma with ductal dilation caused by intrahepatic cholangiocarcinoma

“…This is attributable to periportal fibrosis pathologically demonstrated in all patients with ductal dilation, which may result in increased interstitium, in which intravenous contrast is held in an equilibrium phase (12). This pathologic change is believed to occur in response to extravasated bile in patients with bile duct obstruction (5). This delayed enhancement should be distinguished from the arterial buffer response as a result of portal venous branch obstruction, which can be visualized as segmental or subsegmental enhancement in the arterial phase of a dynamic CT scan (1,3,4) or as transient increased segmental hepatic enhancement in the early phase of a dynamic MR study (1 3).…”

“…Sections of specimens stained with H&E showed findings of bile duct obstruction characterized by pseudoductular or pseudoglandular proliferation, inflammatory reaction in the portal triad (including fibrosis and inflammatory cell infiltration), and bile lake formation and/or intracanalicular cholestasis (5). The former two features were observed in all patients with ductal dilation; however, it is difficult to explain the high signal intensity on T1-weighted images on the basis of these findings.…”

“…Although hepatic parenchymal change after bile duct obstruction has been established in pathologic study (5), its radiologic features have not been well documented. Changes caused by bile duct obstruction often have been confused with or discussed inseparably from those due to portal venous occlusion and the resultant compensatory arterial flow increase (arterial buffer response) (3).…”