An experimental approach of the Doppler perfusion index of the liver in detecting occult hepatic metastases: histological findings related to the hemodynamic measurements in Wistar rats

Image-directed colour Doppler sonography has been successfully introduced f or the detection of hepatic haemodynamic changes in the presence of liver m etastases. The aim of our study was to correlate these haemodynamic changes with the liver histology at the time of measurement. We experimentally ind uced liver metastases in 30 male Wistar rats by inoculating Walker 256 tumo ur subcutaneously. The animals were assigned into three groups of ten and w ere studied sonographically at 4, 7 and 15 days after tumour implantation. Another group of ten normal animals were used as controls. Portal vein and hepatic artery measurements included resistance index (PVRI, HARI) and flow volume (PVFV, HAFV), Doppler perfusion index (DPI) of the liver was calcul ated as the ratio of HAFV/PVFV + HAFV. Liver histology followed each Dopple r measurement. Metastases were first encountered on day 4, as small groups of cells in the connective tissue of the porta hepatis and the portal triad s without apparent vascular association. Distinct elevation of HAFV and DPI was recorded in comparison with the controls (p = 0.0004 and p = 0.0005, r espectively). PVFV reduction was subtle. Up to day 15 there were no signifi cant changes in the measurements. Our data suggest that HAFV and DPI can ef ficiently detect early liver metastases and this is in accordance with exis ting clinical reports. Haemodynamic changes seem to originate from the earl y non-vascular phase of the metastases.