Nuclear magnetic resonance and gamma camera tumor imaging using gadolinium-labeled monoclonal antibodies

Chelate-derivatized monoclonal antibody labeled with paramagnetic gadolinium-3+ ion has been evaluated as a tumor-specific contrast-enhancing agent in nuclear magnetic resonance imaging in the Rauscher murine erythroleukemia system. With 10(-7) M concentrations of Gd3+ delivered to the tumor target, a small but reproducible difference in proton relaxation times (T1S) was observed in excised tumors. Nuclear magnetic resonance imaging of animals, however, failed to show significant contrast enhancement of the tumor; by comparison, gamma camera images with 153Gd-labeled specific antibody did permit clear tumor visualization without subtraction. The potential use of monoclonal antibodies in tumor imaging appears to be far greater in gamma camera and positron imaging than in nuclear magnetic resonance imaging.