Evaluation of the Liver for Metastatic Disease

Erik K. Paulson, MD1, 1Department of Radiology, Duke University Medical Center, Durham, North Carolina.

Semin Liver Dis. 2001;21(2) 

In This Article

Blood Supply

The liver is unique because of its dual blood supply from the portal vein and hepatic artery. Approximately 20% of the blood supply is from the hepatic artery and 80% from the portal vein.[8,9] For most abdominal primary tumors the liver represents the first site to be involved in hematogeneous metastatic spread.[10,11] It is hypothesized that once tumor cells invade the portal venous system, they seed the hepatic parenchyma, which may represent a favorable environment for tumor growth. The blood supply to tiny or microscopic metastases is primarily from the portal venous system.[1] However, by the time metastases are large enough to be detected by imaging, they receive the majority of their blood from the hepatic artery. It is interesting to note that a significant number of liver metastases up to 1.5 cm in size have a distinct residual portal venous blood supply to the tumor periphery.[12,13,14,15] Such dual vascularity in the smallest of lesions may partly explain some of the difficulty in detecting such lesions with imaging techniques.[1]

Metastases are nearly always multiple. As a general rule, they are more frequently encountered in the right lobe than the left. This is likely due to the large mass of the right lobe and, accordingly, its greater blood flow. Furthermore, laminar flow in the portal vein plays a role because metastases from the gastrointestinal tract spread to the liver via the superior mesenteric vein, which preferentially flows into the right lobe.