Pre-operative scanning of the liver for colorectal liver metastases.

The comparative value of staging the extent of colorectal liver metastases by isotope, ultrasound and CT imaging has been assessed in 20 patients considered for inclusion into a randomized trial. Metastases were identified in all patients by CT, but failed in 4 by isotope and 2 by ultrasound scanning. There was often a discrepancy of 25% in estimating tumour replacement between the different modalities and surgical evaluation. As the extent of tumour is an important prognostic factor, initial evaluation should incorporate all three imaging techniques. Relative regional blood flow in tumour and normal liver regions was measured by dynamic liver scintigraphy, showing that 60% have a predominantly arterial blood supply.