Tumor flood volume assays using contrast-enhanced magnetic resonance imaging: Regional heterogeneity and postmortem artifacts

Tumor blood volume (BV), subject to both morphologic and physiologic influe nces, can be measured using contrast-enhanced magnetic resonance imaging (M RI). The aims of this study were to determine whether MRI enhanced with a m acromolecular contrast medium (MMCM) could resolve differences in BV betwee n different tumor types, between different regions within tumors, and withi n the same tumor in life and after death. Tumor BV estimates were based on the MRI signal intensity responses in the tumors and in reference venous bl ood following enhancement with a blood pool MMCM using two mammary adenocar cinoma models, Estimates of BV were made before and immediately following d eath. An in vitro measurement of tumor gadolinium concentration following d eath was correlated with MRI enhancement. Statistically significant differe nces (P < 0.05) were observed in MN-estimated tumor BV between tumor subtyp es, between in vivo and postmortem measurements, and between the tumor peri phery and tumor centers. MRI assays enhanced with a macromolecular contrast agent can resolve blood volume differences between tumor types, between re gions within the same tumor, and between vital and postmortem states. (C) 1 999 Wiley-Liss, Inc.