FOLH1 and neoplasm: Indeed, compounds 13 to 15, which possess different degree of lipophilicity due to different number of Phe moieties (from zero (13) to three (15)) on the spacer, displayed considerable differences in tumor and background uptake as measured by SPECT/CT images from male SCID mice bearing PSMA+ PC3 PIP and PSMA− PC3 flu tumors at 2 h p.i. High gallbladder, liver, and gastrointestinal uptake were observed for 99mTc-15 as compared to that of 99mTc-13.