Characterization of N-ethyl-N-nitrosourea-induced malignant and benign breast tumors in rats by using three MR contrast agents

A carcinogen (N-ethyl-N-nitrosourea)-induced animal tumor model was establi shed to grow malignant and benign breast tumors, In each tumor the pharmaco kinetic characteristics were measured by using three contrast agents, gadol inium-diethylene-triamine-pentaacetic acid (Gd-DTPA; <1 kD), Gadomer-17 (35 kD), and albumin-Gd-DTPA (70-90 kD), Infiltrating ductal carcinomas (IDC) with low, medium, and high Scarf-Bloom-Richardson grades and fibroadenomas (FA) were analyzed. We found that Gd-DTPA could differentiate between FA an d malignant tumors, but not between malignant tumors of low and high grades . In contrast, the intermediate size agent Gadomer-17 could differentiate b etween high-grade and low-grade IDC, but not between low-grade IDC and FA d ue to their similar enhancement patterns (despite their different origins). The largest agent, albumin-Gd-DTPA, was capable of differentiating both, b ut the low contrast-to-noise ratio was its major technical concern, The res ults in this breast tumor model suggest that macromolecular agents provide useful information for differential diagnosis among IDCs of various grades, but they do not provide superior information than Gd-DTPA for differential diagnosis between IDC and FA, J, Magn, Reson,Imaging 1999;9:177-186. (C) 1 999 Wiley-Liss, Inc.