A comparison of methods to measure the percentage hepatic replacement with colorectal metastases.

The percentage hepatic replacement (PHR) with liver metastases has been recognised as an important factor for patient management, prognosis, and clinical trial evaluation. The PHR can be assessed by various methods including ultrasound, radioisotope, or computed tomography (CT) imaging, or by inspection and palpation at laparotomy. We report a prospective study comparing these methods of PHR assessment in 56 consecutive patients with colorectal liver metastases. When all four methods were used complete agreement was achieved in only 35% of cases (9/26). The three imaging techniques agreed in only 37% of cases (14/38). Overall, the correlation between different methods was poor with a tendency for surgery to underestimate the PHR. However, CT and surgery agreed in 81% of cases (21/26), and CT gave a higher estimate than surgery in each of the other five patients. With such variability in the estimates of PHR derived from these different techniques, consideration must be given to which technique is used. It is concluded that CT is probably the most accurate for PHR assessment at present.