One patient with whom the extent of progression of perihilar cholangiocarcinoma was evaluated by dynamic computed tomography (CT)

For any hepato-biliary-pancreatic disease, blood flow information obtained by multiphase imaging is indispensable for primary lesion detection, qualitative diagnosis, disease stage diagnosis, therapeutic efficacy determination, and postoperative complication screening⁽¹⁾. Patients with malignant tumors are often followed up after treatment, and contrast CT in the portal phase is then in general use.

Although contrast magnetic resonance imaging (MRI) with Gadoxetate disodium(Gd-EOB-DTPA) is recommended for detection of primary and metastatic liver cancer⁽¹⁾, there are difficulties with MRI throughput, etc., and contrast CT remains in frequent use in clinical practice.

 Qualitative diagnosis of hepatocellular carcinoma (HCC) is made on the basis of wash-out and capsule dark staining in the portal and/or equilibrium phases, following from dark staining in the arterial phase. Optimization of the arterial phase is important, because detection of intra-lesional hypervolemia in not only hypervolemic HCC but also ischemic HCC enables treatment.

In addition, for localized treatments such as surgery, radiofrequency ablation, and transcatheter arterial embolization, elucidation of the relationship between the lesion and intrahepatic blood and lymphatic vessels is important for the treatment strategy. In gallbladder cancer, bile duct cancer, and pancreatic cancer, the dark staining pattern differs according to the proportions of tumor cell components and fibrous interstitial tissue components.
If the content of tumor cell components is high, dark staining in the arterial phase is often seen, whereas if the content of fibrous interstitial tissue components is high this leads to delayed dark staining in the equilibrium phase. Diagnosis in both the portal and equilibrium phases is necessary for determining the resection range and locating hepatic metastases. As there is a limit to the detection capacity of contrast CT for hepatic metastases, if signs suggesting hepatic metastases are detected by contrast CT in accordance with the appropriate imaging protocol, it is preferable to then be proactive in performing additional Gadoxetate disodium(Gd-EOB-DTPA) contrast MRI.