A reporter conjugate for non-invasive detection (e.g., imaging) of matrix metalloprotease (MMP) gene expression in vivo is disclosed. The conjugate includes a targeting nucleic acid linked to a contrast agent, such as a paramagnetic label that can be used with magnetic resonance (MR) imaging. The targeting nucleic acid can be an antisense strand that hybridizes to a portion of a messenger RNA encoded by the gene whose expression is to be imaged. In some embodiments, the contrast agent is a chelated metal such as gadolinium or dysprosium. The invention also features methods to detect MMP gene expression in various tissues, including the brain.
