Extended Data Fig. 2: FLT enhancement of a representative mCRC specimen from a clinical trial conducted at Leiden University.
Histology (a), fluorescence intensity (b), and FLIM (c) images of an mCRC specimen from a patient injected with 0.1 mg/kg ICG 24 h prior to surgery. Imaging was performed in 10 µm thick sections obtained from an FFPE tissue block. Histologically confirmed tumor boundary is shown in the histology (yellow line) and intensity (red line) images. The fluorescence intensity image (b) indicated ICG accumulation primarily around the tumor boundary (‘rim-fluorescence’). Despite the apparent absence of ICG, the FLT in the tumor core (0.74 ± 0.02 ns) was significantly longer (p < 0.001) than the surrounding normal liver parenchyma (0.61 ± 0.04 ns), indicating the presence of ICG in the tumor. Violin plots show the distribution of FLT, d, and intensity, e, across 18 ROIs obtained from the histologically determined tumor (11 ROIs), inflamed tumor stroma (3 ROIs), and normal hepatocyte regions (3 ROIs). f, ROC curves for tumor (tumor + inflamed tumor stroma) (14 ROIs) vs. normal tissue (15 ROIs) classification for this specimen yielded an accuracy (AUC) of 94% using fluorescence lifetime (red) and only 4% for intensity (green) based classification. The dashed lines in d and e represent the threshold FLT (0.68 ns) and intensity (42.7 AU), respectively, corresponding to the highest accuracy as calculated from the ROC curves.