GRPR and neoplasm: Compared to previously reported 99mTc-radiopeptides, which are based on the full-length BBN or its truncated BBN(7–14) octapeptide fragment [25], the 99mTc-N4-GRP(18–27) showed high GRPR selectivity and superior in vivo characteristics in tumor-bearing mice, such as faster renal clearance and improved tumor to background ratios.