Radiolabeled peptide analogs targeting the cholecystokinin-2 receptor (CCK2R), overexpressed in different tumors, such as small cell lung cancer, stromal ovarian cancers, gastrointestinal stromal tumors, astrocytoma and especially medullary thyroid carcinoma (MTC), have shown to be very promising for application in diagnosis and therapy [6,7]. Here, CCKBR is linked to gastrointestinal stromal tumor.