Dual-modality contrast agents are disclosed herein, having the general formula:R1 includes a chelating moiety that is chelated to a Mn2+ isotope. The disclosed contrast agents differentially target a wide range of malignant tumor tissues, and can be simultaneously used as contrast agents for both magnetic resonance imaging (MRI) and positron emission topography (PET) imaging. Accordingly, the disclosed contrast agent can be used in diagnosing and monitoring solid tumor cancers.
