[Ga-68]MTP220 is a novel PET probe composed of a small peptide and Ga-68 chelate for specific imaging and characterization of aggressive solid tumors. Similar to MT218, Using the PET imaging scan [Ga-68]MTP220 is able to provide sensitive detection and characterization of a broad spectrum of aggressive human cancers. It has several advantages over the existing PET probe, e.g. [18F] FDG, including high specificity to aggressive solid tumors, low background noise, broad applications in many types of human cancers, the ability for quantitative characterization and risk-stratification of aggressive solid tumors. [Ga-68]MTP220 can readily be used in the existing imaging protocols of PET, PET/CT, or PET/MRI in clinical cancer management. The imaging probe can also be used to monitor therapeutic response.