a. Maximum-intensity projection (MIP) μPET/CT, transaxial CT, and transaxial μPET/CT slices obtained 24h after administration of [89Zr]DFO-scFv in mice bearing LTL-545 PDX tumors. b. Tumor/blood and tumor/muscle ratio of [89Zr]DFO-DLL3-scFv (with scFv block) at 2h, 4h, and 24h in mice bearing LTL-545 PDX xenografts. ns= not significant, * p < 0.05, *** p < 0.001. c. Tumor/blood and tumor/muscle ratio of [89Zr]DFO-DLL3-scFv in LTL-545 (DLL3HI), LTL-331R (DLL3LOW) and LTL-484 (DLL3NEGATIVE) models at 24h post-injection. * p< 0.05, *** p < 0.001. d. Biodistribution data of [89Zr]DFO-scFv from selected tissues in LTL-545, LTL-331R and LTL-484 models at 24h post-injection.