Doppler perfusion index in detection of colorectal cancer liver metastases

Colorectal cancer is the second most common cause of cancer death. Approximately 50% of patients develop liver metastases within two years. At least 30% of colorectal cancer patients with apparently no liver involvement harbour liver metastases at the time of surgery. Detection of these micro metastases could direct those patients for adjuvant treatment modalities and more intensive surveillance. It was recently found that the ratio of hepatic arterial blood flow and the sum of hepatic arterial and portal blood flow (called Doppler perfusion index- DPI) was significantly greater in colorectal patients with liver metastases. However, the cause of this effect is still unknown. We analysed hepatic arterial and portal blood flow in three groups of patients (healthy controls, patients with primary colorectal cancer without apparent liver metastases and patients with obvious liver metastases). Patients with liver metastases had significantly increases arterial hepatic blood flow compared to patients without liver involvement (p< 0.025). Healthy controls had significantly larger portal vein cross-sectional area (p<0.025), as well as portal blood flow (p<0.025) compared to patients with colorectal cancer and patients with liver metastases. Doppler perfusion index was significantly greater in patients with liver metastases compared to both healthy controls (p<0.025) and patients with primary colorectal cancer (p<0.025). These results prove the potential role of DPI in selecting patients for adjuvant treatment. Also, significantly reduced portal blood flow in patients with either solitary primary colorectal cancer or liver metastases speaks strongly in favour of the existence of the humoral vazoactive substance in colorectal cancer patients.