NTSR1 and neoplasm: 99mTc-HYNIC ([99mTc]1) and 99mTc-tricarbonyl ([99mTc]2) showed significantly reduced tumor uptake at 4 h p.i. (p < 0.0001 for ([99mTc]1,p = 0.0069 for ([99mTc]2), comparing preinjected animals with the controls (Figure 3), thereby confirming the highly NTSR1-specific tumor uptake of both radioligands in vivo.