Evaluation on the defect of the ring-like enhancement in metastatic liver tumors on CT during hepatic arteriography;diagnosis of invasion on the surface or intrahepatic vessels

Forty-one metastatic nodules in contact with the liver surface or intrahepatic vessels were evaluated by CT during hepatic arteriography (CTA). In the nodules which showed invasion on the surface or vessels, the defects of the ring-like enhancement were clearly seen in coincidence with disappearance of the parenchyma around masses. Otherwise, in the nodules which did not show the defect, the liver parenchyma existed between masses and the surface or vessels, even if the parenchyma became thin or fibrotic. The ring-like enhancement on CTA is considered as the non-tumorous tissue and it's defect strongly suggests the direct invasion to the liver surface or vessels.