Figure 4

In vivo tumor detection in a mouse via TRI.

(a) T2-weighted coronal MRI image. (b) In vivo GFP fluorescence image. The presence of tumor was screened by the MRI and fluorescence images. Yellow-orange arrowheads indicate the assumed tumor region. The in vivo experiment was performed after the tumor developed to the brain surface. (c) White light image of exposed brain tumor that was in contact with the quartz window. Yellow dashed box indicates region of measured TRI image. (d) In vivo peak-to-peak TRI image. Tumor regions (blue arrow) were well discriminated from normal brain regions (black arrow) in the live animal. (e–g) White light, TRI, and GFP fluorescence images of extracted whole brain, respectively. The gross tumor regions, determined by each image (blue arrowheads), were well discriminated in the TRI image and even in the white light image (violet arrow). The tumor region in GFP fluorescence image (g) seems to be broader than that in THz image (f). The discrepancy may be accounted for by that GFP fluorescence image results in part from the diffusive fluorescence signal from the tumors deep in the tissue (Supplementary Figs 3 and 4).