18F-FPRGD2 PET/CT imaging of integrin αvβ3 in renal carcinomas: correlation with histopathology.

This study aimed to correlate (18)F-FB-mini-PEG-E[c(RGDyK)](2) ((18)F-FPRGD2) uptake to integrin αvβ3 expression and angiogenesis in renal tumors. (18)F-FPRGD2 PET/CT was performed on 27 patients before surgical resection (median 4 d) of a renal mass. The (18)F-FPRGD2 uptake was compared with integrin αvβ3, CD31, CD105, and Ki-67 using immunohistochemistry; with placental growth factor and vascular endothelial growth factor receptors 1 and 2 using reverse transcription polymerase chain reaction; and with vascular endothelial growth factor A isoforms using enzyme-linked immunosorbent assay. Overall, (18)F-FPRGD2 uptake significantly correlated (P < 0.0001) with integrin αvβ3 expression in renal masses. However, it correlated only with integrin αvβ3-positive vessels in the group of papillary carcinomas whereas it correlated with integrin αvβ3 expression by tumor cells in the clear cell carcinoma group. (18)F-FPRGD2 uptake reflects the expression of integrin αvβ3 in renal tumors but represents angiogenesis only when tumor cells do not express the integrin.