Figure 3.

Imaging of TNBC metastasis by dynamic contrast MRI, fluorescence imaging of excised brain after animal euthanasia, and fluorescence microscopy of histological sections. (a) MRI scans of mouse brains with MDA-MB-468 tumors (EGFR+) after iv injection of contrast agents MultiHance, P/Gd-DOTA/cetuximab/MsTfR-mAb/Alexa-680 (targeted NIA), and P/Gd-DOTA/trastuzumab/MsTfR/Alexa-680 (nontargeted NIA). Bright contrast was observed with targeted NIA (red circles) and was maintained for a prolonged time in comparison with MultiHance (green circles) or nontargeting NIA (blue circles). (b) Image quantification based on intensities of regions of interest (ROI; see Figure S3). Intensity from ROIs was calculated using Leica MM AF 1.6 software and normalized at each time point vs ROI intensity outside the tumor area. Targeted NIA showed significant difference in MRI contrast intensity vs MultiHance or nontargeted NIA at 60 min to 3 h time points (****p < 0.0001). (c) Fluorescence of drug targeted into tumor area was used for brain imaging by Xenogen IVIS 200 (left) and for tumor section fluorescence microscopy (right). By microscopy of brain sections, targeted agent (red) was localized in tumor cells around the nuclei (DAPI counterstain, blue). Nontargeted agent was detected only in blood vessels in very small amount.