Potential of labeling monoclonal antibodies for positron emission tomography and magnetic resonance imaging.

Monoclonal antibodies have been suggested as potential agents for diagnosing tumors and other disorders due to the great specificity of monoclonal antibodies. Two new approaches to labeling of monoclonal antibodies involve the attachment of paramagnetic compounds which can be used with nuclear magnetic resonance (MR) imaging or attaching to a positron-emitting radionuclide for use with positron emission tomography (PET). In the case of agents for MR imaging, significantly greater amounts of compound need to be administered than in the radionuclidic case. The limitations of this technique when attaching a large number of paramagnetic agents to a monoclonal antibody are evaluated and discussed. In the case of PET, several radionuclides are compared and contrasted and examples are given in animal models where significant uptake in target tissue is obtained in time frames suitable for imaging. The ultimate potential of these two modalities is evaluated.