Hepatic colon cancer metastases in mice: Dynamic in vivo correlation with hypoechoic rims visible at US

PURPOSE: To use videomicroscopy of tumor-bearing livers of live mice to dep ict tumors directly to determine the exact nature of rims seen on correspon ding ultrasonographic (US) scans. MATERIALS AND METHODS: Seventy-six hepatic colorectal cancer metastases wer e studied in exteriorized livers of 18 mice by using intravital microscopy, US, and histologic examination of the same tumors. RESULTS: Hypoechoic rims correlated with distended sinusoidal spaces in viv o. These spaces surrounded only locally invasive tumors (mean diameter, 0.8 5 mm) that had obstructed the supplying terminal portal venules. These spac es, containing adherent leukocytes and tumor cells, gave rise to new tumor vasculature. Results of histologic examination of rims (portal inflammation , congested or compressed sinusoids, cell atrophy) correlated with leukocyt e endothelial adherence, occluded sinusoids, and new vessel formation in vi vo. CONCLUSION: Unlike results from previous studies, dynamic in vivo observati ons of peritumoral rims demonstrated distended sinusoidal spaces giving ris e to new tumor-penetrating vessels. These sinusoids arose around locally in vasive tumors and were associated with more advanced intrahepatic disease. These dynamic observations provide a pathophysiologic explanation for previ ous histologic correlates of peritumoral rims.