Various methods of use for surface enhanced spectroscopy-active composite nanoparticles (SACNs) are provided. SACNs are submicron-sized particles or labels can be covalently or non-covalently affixed to entities of interest for the purpose of quantification, location, identification, tracking, and diagnosis. The various methods include administering a SACN nanoparticle imaging agent to a patient, scanning the patient using a system that can perform spectral imaging and generating a spectrum or image of an internal region of the patient. A method, for diagnosing an abnormal pathology as well as a method for labeling an animal with a SACN are also provided.
