3D MR angiography of intratumoral vasculature using a novel macromolecularMR contrast agent

Noninvasive methods to visualize blood flow in the intratumoral vasculature have not previously been studied. In the present study, the use of a novel intravascular MR contrast agent with a generation-6 polyamidoamine dendrim er core (G6-(1B4M-Gd)(192); MW: 175kD) was investigated, and the vasculatur e in experimental tumors was visualized using 3D MR angiography (MRA). Xeno grafted tumors in nude mice of two different histologies-KT005 (human osteo genic sarcoma) and LS180 (human colon carcinoma)-were used to obtain 3D MRA using G6-(1B4M-Gd)(192) and Gd-DTPA. The contrast MR sectional images were correlated with the corresponding histological sections. The intratumoral vasculature in the KT005 tumor was clearly visualized by 3D MRA, which beca me more evident with the growth of the tumor xenograft. In contrast, the in tratumoral vasculature in the LS180 tumor was sparser and much less develop ed than that in KT005 tumors. Blood vessels with a diameter as small as 100 mum based on histology were visualized using 0.033 mmol Gd/kg of G6-(1B4M- Gd)(192). In conclusion, intratumoral vasculature with a 100-mum diameter w as visualized better using 3D MRA with G6-(1B4M-Gd)(192) than with Gd-DTPA. (C) 2001 Wiley-Liss, Inc.