The use of duplex sonography in the detection of colorectal hepatic metastases.

Conventional imaging techniques are of limited value in identifying small liver metastases. Indirect methods of measuring blood-flow have shown that metastases may be associated with subtle changes in liver blood-flow. Doppler ultrasonography has the ability to measure liver blood-flow directly. In this study, the role of duplex sonography in the detection of hepatic metastases was evaluated. Hepatic arterial and portal venous blood-flows were measured in 30 patients awaiting surgery for colorectal cancer and 16 controls. The ratio of hepatic arterial: portal venous blood-flow (Doppler flow ratio; DFR) and the ratio of hepatic arterial:hepatic arterial and portal venous blood-flow (Doppler perfusion index; DPI) were calculated. Clear separation of the DPI and DFR values of controls and patients with histologically confirmed liver metastases was observed (P less than 0.001). The data suggest that the measurement of liver blood-flow by duplex sonography may be of value in the diagnosis of colorectal liver metastases.