Fig. 5

In vivo phantom and animal experiments. a the PET image of the animal phantom showed the same radioactivity of ¹⁸F-FDG in the capillaries. b, c the optical image and the quantitative analysis showed a higher signal intensity of the mixture of Gd₂O₃:Eu-100@PVA and ¹⁸F-FDG compared with ¹⁸F-FDG alone (left: ¹⁸F-FDG (84 μCi, 20 μl) + Gd₂O₃:Eu@PVA (2 mg), right: ¹⁸F-FDG (84 μCi, 20 μl)). d Gd₂O₃:Eu-100@PVA enhanced the optical signal of ¹⁸F-FDG, showing an obvious tumor optical signal. e CLI displayed no obvious signal of the tumor. f the TNR of the tumor was also increased by the Gd₂O₃:Eu-100@PVA NP. g the PET image of the tumor-bearing mouse injected the mixture of Gd₂O₃:Eu-100@PVA and ¹⁸F-FDG displayed no obvious tumor signal. h the Gd₂O₃: Eu 100@PVA enhanced the optical signal of the tumor. i the tumor was resected with the guidance of the optical image. j the optical signal intensity of the tumor was significantly higher than that of the surrounding normal tissue. k, l the optical image, and the quantification showed the significantly higher optical signal intensity of tumor compared with muscles and other organs obtained from the tumor-bearing mouse