Comparison of the Doppler perfusion index and intraoperative ultrasonography in diagnosing colorectal liver metastases. Evaluation with postoperative follow-up results.

OBJECTIVE: The authors compared the accuracy of intraoperative ultrasound with the Doppler perfusion index (DPI) in the detection of occult liver metastases. SUMMARY BACKGROUND DATA: Intraoperative ultrasound is well recognized to be very sensitive in the detection of small liver tumors. Previous studies using duplex/color Doppler sonography have shown that the measurement of the DPI (hepatic arterial to total liver blood flow ratio) can detect the presence of occult colorectal liver metastases. METHODS: Intraoperative ultrasound and DPI were evaluated in 90 patients with colorectal cancer with apparently disease-free livers (on the basis of computed tomography scans and laparotomies). All patients subsequently were observed for follow-up with 3 monthly clinical examinations, ultrasound scans, and yearly computed tomography scans. RESULTS: Intraoperative ultrasound detected liver metastases in 4 of the 23 patients who subsequently developed overt liver metastases during 1-year follow-up. However, DPI predicted the development of hepatic metastases in all 23 cases. CONCLUSION: The results suggest that DPI is more sensitive than intraoperative ultrasound in the early detection of occult colorectal liver metastases. The Doppler technique can identify patients at high risk, suitable for adjuvant therapy. The routine use of intraoperative ultrasound in screening for occult colorectal liver metastases is not recommended.