Early changes in liver perfusion caused by occult metastases in rats: Detection with quantitative CT

PURPOSE: To determine whether computed tomography (CT) can depict liver hem odynamic changes caused by occult hepatic micrometastases in rat. MATERIALS AND METHODS: Liver micrometastases (mean diameter, 500 mum +/- 30 0) were produced in seven BD IX rats by injecting 10(7) DHDK12 PROb colorec tal carcinoma cells into the spleen. Macrometastases (mean diameter, 7 mm /- 3) were produced in four other rats. Five normal rats were studied as co ntrols. CT images were obtained every 300 msec for 30 seconds during the in jection of 1 mL per kilogram of body weight of contrast medium. The time-at tenuation curves of the aorta, portal vein, and liver were used to calculat e liver perfusion with a deconvolution model designed for the dual blood su pply. RESULTS: Micrometastases in an apparently normal liver caused a 34% decreas e in portal blood flow and a 25% increase in the mean transit time for the blood to pass through the liver. These findings suggest increased resistanc e in the sinusoidal capillaries. Similar but greater changes were found in the macrometastases. CONCLUSION: Occult liver micrometastases in rats generate changes in liver perfusion that can be detected with CT.