IGF1R and neoplasm: With regard to the choice of fluorophore to conjugate to IGF-1R antibodies, we used DyLight 650 and 550 dyes because our previous studies demonstrated that these longer-wavelength dyes had increased depth of penetration and ability to detect the smallest tumor deposits and provided the highest tumor-background ratios (TBRs), resistance to hemoglobin quenching, and specificity compared to shorter wavelength dyes [24].