Figure 2: ¹⁹F-based MRI cell tracking.

bSSFP images of mammary fat pad tumors acquired 48 hours post PFC administration. (a) 4 days post 4T1 cancer cell injection: ¹⁹F signal is detected throughout the entire tumor with a higher density visualized within the center of the tumor (pink) when compared to the periphery. (b) 3 weeks post 4T1 cancer cell injection: ¹⁹F signal is detected, heterogeneous in density, only along the periphery of the tumor. Cropped images that are placed below each of the main images show the adjacent image slices (1 mm) containing ¹⁹F signal. The color bar demonstrates range of ¹⁹F spins. ¹⁹F signal is also detected in reference tubes (ref), bone marrow and spleen. Scale bars represent 5 mm.