Fig. 2

Representative images per dose group and per optical imaging method for ex vivo analyses, including MDSFR/SFF spectroscopy. Columns represent the four dose groups: 4.5 mg (a–f), 10 mg (g–l), 25 mg (m–r), 50 mg (s–x). Rows represent the imaging modality, in the upper part a white light image and in the lower part the representative fluorescence image. Tumor tissue is delineated with a dashed line. Scale bars represent 1 cm. I Mean fluorescence intensity (MFI) of normal tissue (gray) and tumor tissue (black) are depicted per dose group on the left y-axis, the right y-axis shows the tumor-to-background ratio per patient per dose group for macro-segmentation analyses, in II for MDSFR/SFF spectroscopy measurements and in III for micro-segmentation analyses. Fluorescence images are scaled using the most optimal minimum and maximum displayed value. Boxplot centerline is at median, the bounds of the box at 25th to 75th percentiles, the whiskers are depicting the min–max, tumor-to-background ratio data are depicted per patient; line indicates median value per dose group. Asterisk denotes significant (P < 0.05, Kruskal–Wallis test) values. Obelisk denotes significant (P < 0.05, Mann–Whitney U-test) values. FFPE formalin-fixed, paraffin embedded, MDSFR/SFF multi-diameter single-fiber reflectance/single-fiber fluorescence. Q.μ^f_a,x the product of the quantum efficiency across the emission spectrum, Q[-], where Q is the fluorescence quantum yield of IRDye-800CW and μ_af [mm⁻¹] is the tracer absorption coefficient at the excitation wavelength