Polylysine-
DTPA-Gd, a new MR
contrast agent, was injected into the aorta of rats 7 days after C6
glioblastoma was implanted in their brains; MR imaging was performed 3 days later. The imaging was done at two field strengths: (1) 1.5 T with a 3-mm slice thickness and in-plane resolutions of 600 microns and (2) 9.4 T with a 125- or 500-microns slice thickness and in-plane resolutions of 95 microns. In animals injected with
polylysine-
DTPA-Gd (1 microgram or more per rat), the T1-weighted images and mixed T1, T2 images of the C6
glioblastoma revealed a higher signal intensity at the marginal region between
tumor and normal brain than that seen in surrounding normal brain. The central
tumor region had a low signal intensity. The concentration of Gd in the C6
glioblastoma, after injection of 1 microgram
polylysine-
DTPA-Gd per rat, was calculated to be 0.14 mumol/l. The central
tumor region also had a low signal intensity in animals that were not injected with the
contrast agent, but the margin between
tumor and normal brain was resolved poorly, if at all. The
polylysine-
DTPA-Gd revealed the microvasculature of the C6
glioblastoma in the 125-micron-thick slices obtained at 9.4 T. This is the first study to reveal the utility of the 9.4-T MR imager for examination of
glioblastomas in situ and to demonstrate the utility of
polylysine-
DTPA-Gd as a
contrast agent for the definition of the margin between
glioblastoma and normal brain tissue.