Highly sensitive imaging of diseased tissues such as cancer is attractive because it potentially allows for early tumor detection. One of the problems associated with conventional, low molecular weight imaging probes is the limited tumor: background ratio. To circumvent this, imaging probes were conjugated to polymeric carriers and were surprisingly found to accumulate specifically at cancer sites. This invention describes an innovative targeting strategy for the selective identification of solid tumors by means of polymer-NIR fluorochrome conjugates which accumulate selectively within cancerous tissue relative to normal tissue.