1. A method, comprising: 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; 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; obtaining second spectral image data, which includes a second component corresponding to a second K-edge based contrast agent administered to the subject; decomposing the second spectral image data into at least the second component; and reconstructing the second component thereby generating a second image of the second K-edge contrast agent.