A method includes obtaining first spectral image data, which includes at least a first component corresponding to a targeted first K-edge based contrast agent administered to a subject if a target of the targeted first K-edge based contrast agent is present in the subject, decomposing the first spectral image data into at least the first component, reconstructing the first component thereby generating a first image of the targeted first K-edge contrast agent, determining if the targeted first K-edge contrast agent is present in the first image, and generating a signal indicating the targeted first K-edge contrast agent is present in the first image in response to determining the targeted first K-edge contrast agent is present in the first image.
