The present invention is directed to novel non-invasive diagnostic tools/compounds to image cancers, especially, melanoma, including metastatic melanoma in vivo. The present compounds exhibit enhanced uptake in cancerous cells and tissue and decreased renal uptake in kidney, evidencing favorable pharmacokinetics of compounds of the present invention. The compounds according to the present invention represent an advance in the diagnosis and treatment of melanoma, including metastatic melanoma using non-invasive molecular imaging techniques. The novel probes of the present invention are also useful for initiating therapy for melanoma as well as monitor patients' response to chemotherapy treatments and other interventions or therapies used in the treatment of melanoma/metastatic melanoma. Compounds according to the present invention may be used as diagnostic tools for a number of conditions and diseases states as well as therapeutic agents for treating such conditions and disease states.