The present invention provides compositions suitable for use as biomarkers of vulnerable plaques as well as methods for the use of such compositions. In preferred embodiments, specific molecular imaging agents are provided that permit the selective identification of vulnerable plaques in coronary and other arteries using non-invasive imaging methods. Such specific molecular imaging agents comprise a binding partner linked to a detectable label that can be used in vivo to visualize vulnerable plaques. In certain preferred embodiments, the binding partner is a peptide that binds selectively to a component of a vulnerable plaque. In other preferred embodiments, the binding partner is an antibody that binds selectively to a component of a vulnerable plaque. In other preferred embodiments, the binding partner is a portion of a polypeptide displayed by a bacteriophage that binds selectively to a component of a vulnerable plaque. In preferred embodiments, the component of a vulnerable plaque is myeloperoxidase or a portion thereof.