TUMOR IMAGING WITH A MACROMOLECULAR PARAMAGNETIC CONTRAST AGENT - GADOPENTETATE DIMEGLUMINE-POLYLYSINE

Rationale and Objectives. We evaluated magnetic resonance (MR) contras t enhancement of tumor tissue following injection of the macromolecula r conjugate, gadopentetate dimeglumine-polylysine. Methods. T1-weighte d MR imaging scans were performed on female Fisher-344 rats with subcu taneously implanted mammary adenocarcinoma tumors. Following the basel ine scan, gadopentetate dimeglumine-polylysine or gadopentetate dimegl umine was injected at a dose of 0.1 mmol gadolinium per kilogram. Resu lts. Gadopentetate dimeglumine-polylysine injection resulted in a maxi mum enhancement of tumor contrast of 310 +/- 60% (n = 7). Tumor tissue remained enhanced and well defined for several days after gadopenteta te dimeglumine-polylysine injection. Gadopentetate dimeglumine injecti on at the same dose resulted in a 70 +/- 25% (n = 4) maximal tumor enh ancement and a corresponding 25 +/- 4% muscle enhancement. Conclusion. Gadopentetate dimeglumine-polylysine provides higher, more sustained tumor contrast than does gadopentetate dimeglumine for the same dosage of gadolinium.