Image-directed Doppler ultrasonography: a novel technique for the diagnosis of colorectal liver metastases.

Image-directed Doppler ultrasonography has been used to measure changes in hepatic arterial and portal venous blood flows in 22 controls and 88 patients with colorectal cancer. Doppler Perfusion Index, (DPI, ratio of hepatic arterial to total liver blood flow) and Doppler Flow Ratio (DFR, ratio of hepatic arterial to portal venous blood flow) of controls and patients with overt liver metastases were clearly separated (p < 0.0001). There was a significant reduction in the Hepatic Arterial Resistive Index (HARI) of patients with overt liver metastases (p < 0.0001). Percentage Hepatic Replacement (PHR) by metastases, measured using a computed tomography scanner, did not correlate with DFR or DPI. The results suggest that the measurement of hepatic perfusion changes using image-directed Doppler ultrasonography may be of value in the detection of small liver metastases.