Intrahepatic inflow areas of the drainage vein of the gallbladder: Analysis by angio-CT

Background. The drainage veins of the gallbladder (cystic veins) are important hepatic metastatic routes of gallbladder cancer. We studied the cystic vein inflow portions of the intrahepatic vessels by computed tomography during angiography (angio-CT). Methods. The subjects were 27 unoperated pancreatic-biliary patients. After superselective catheterization of the cystic artery, angio-CT was performed, and cystic veins and sinusoidal filling were visualized. We identified the cystic vein inflow routes and the vessels they fed. Results. We found 72 cystic veins in 26 patients. All cystic veins flowed into the intrahepatic portal branches or sinusoids. The cystic veins took either of two routes: one into the liver through the hepatic hilum (17 patients, 21 veins), taken mainly by the portal branch for subsegment 4a (P4a), the anterior portal branch, and the umbilical portion of the portal branch; and the other through the hepatic bed (23 patients, 51 veins), taken mainly by S4a sinusoid, S5 sinusoid, P4a, and P5. Conclusions. Angio-CT is useful for detecting the cystic vein inflow portions of the intrahepatic vessels. It makes possible identification of areas where there is a possibility for micrometastasis of the gallbladder cancer.