**3. Peptide-Based Probes**

Peptide tracers have played vital roles in MI due to their unique advantages, notably their low molecular weight and ability to bind tumor biomarkers specifically, with low toxicity to surrounding non-cancer cells. Multiple tracers, like [68Ga]Ga-dodecane tetraacetic acid labeled RGD2 ([68Ga]Ga-DOTA-RGD2; RGD: Arg-Gly-Asp), [68Ga]Gaprostate specific membrane antigen ligand ([68Ga]Ga-PSMA) with conjugates of N,N' bis[2 -hydroxy-5-(carboxyethyl)benzyl]ethylene diamine-N,N -diacetic acid (HBED-CC) or DOTA, [68Ga]Ga-DOTA-DGlu-Ala-Tyr-Gly-Trp-(N-Me)Nle-Asp-1-Nal-NH2 ([68Ga]Ga-DOTA-MGS5), [111In]In-DTPA-octreotide, and other somatostatin analogs have been developed for imaging TCs, particularly MTCs and RR-DTCs [80].
